期刊文献+
任意字段
题名或关键词
题名
关键词
摘要
作者
第一作者
机构
刊名
分类号
参考文献
作者简介
基金资助
栏目信息
共找到242篇文章
< 1 2 … 13 >
每页显示 20 50 100
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
显示方式：
Crystal structure evolution and thermal stability of high explosive RDX characterized by in situ single crystal X-ray diffraction 认领 引用
1
作者 Peilin Yang Liyuan Wei +5 位作者 Jinkun Guo Chunbo Shi Yiru Chen Yu Liu Xiaoan Wei Shiliang Huang 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2026年第5期280-287,共8页
Crystal structure evolution of energetic crystals under external stimuli can significantly change their chemical/physical properties and profoundly impact the effectiveness and safety of weapon systems.In this study,t... Crystal structure evolution of energetic crystals under external stimuli can significantly change their chemical/physical properties and profoundly impact the effectiveness and safety of weapon systems.In this study,the evolution of the crystal structure of the high explosive 1,3,5-trinitro-1,3,5-triazine(Cyclotrimethylenetrinitramine,RDX)is investigated within the temperature range of−100℃–100℃ using in situ single-crystal X-ray diffraction technology.The thermal expansion rates of unit cell along the crystal axes and the inter-layer spacings of the mainly exposed crystal planes(111),(210)and(021)are calculated.Compared to the linear expansion of the unit cell,the increase of the atomic thermal vibrations,described by atomic displacement parameter(ADP),of RDX follows an exponential function.The ADP of the nitro group increases much faster than those of the central ring,especially at high temperatures,which is considered to be the cause of the molecular decomposition of RDX,and is consistent with calculation results identifying the−NO₂bond as the trigger of explosive decomposition.A tendency from AAE to AAA conformation is found for the RDX molecule,according to the orientation angle change of the nitro groups relative to the central ring,which causes the compression of the central ring.By comparing the crystal structure evolution behavior of RDX with HMX,it is concluded that the smaller unit cell expansion,the stronger atomic vibration and the lower molecular deformation ability of RDX are not conducive to buffering external energy,which are the main reason for the lower thermal stability,higher mechanical sensitivity and absence of phase transition before thermal decomposition of RDX,compared to HMX.These results will provide a promising way to characterize the crystal structure evolution of energetic materials for the comprehensive understanding of their properties and performance at the atomic and molecular levels. 展开更多
关键词 Energetic material Crystal structure evolution 1,3,5-Trinitro-1,3,5-triazine(RDX) Molecular conformation Thermal stability
暂未订购 下载PDF
Pore structure evolution of lacustrine organic-rich shale from the second member of the Kongdian formation in the Cangdong Sag,Bohai Bay Basin,China 认领 引用 被引量：9
2
作者 Xiao-Ping Liu Ming Guan +6 位作者 Zhi-Jun Jin Zhe Cao Jin Lai Lun-Ju Zheng Wen-Qi Li Biao Sun Shan-Yong Chen 《Petroleum Science》 SCIE CAS CSCD 2022年第2期459-471,共13页
Pyrolysis experiments were conducted on lacustrine organic-rich shale from Cangdong Sag in Bohai Bay Basin,China,to investigate the impact of hydrocarbon generation on shale pore structure evolution.Thermal evolution ... Pyrolysis experiments were conducted on lacustrine organic-rich shale from Cangdong Sag in Bohai Bay Basin,China,to investigate the impact of hydrocarbon generation on shale pore structure evolution.Thermal evolution is found to control the transformation of organic matter,hydrocarbon products characteristics,and pore structure changes.Furthermore,pore volume and specific surface area increase with increasing maturity.In low-mature stage,the retained oil content begins to increase,pore volumes show slight changes,and primary pores are occluded by the generated crude oil of high molecular weight and density.In the oil-window stage,the retained oil content rapidly increases and reaches maximum,and pore volumes gradually increase with increasing thermal maturity.At high mature stage,the retained oil content begins to decrease,and the pore volume increases considerably owing to the expulsion of liquid hydrocarbon.In over mature stage,natural gas content significantly increases and kerogen transforms to asphalt.Numerous organic pores are formed and the pore size gradually increases,resulting from the connection of organic pores caused the increasing thermal stress.This study lays a foundation for understanding variation of hydrocarbon products during the thermal evolution of lacustrine shales and its relationship with the evolution of shale reservoirs. 展开更多
关键词 Lacustrine shale Pyrolysis Thermal maturity Pore structure evolution Hydrocarbon generation evolution
暂未订购 下载PDF
Crystal Structure Evolution of the Cu-rich Nano Precipitates from bcc to 9R in Reactor Pressure Vessel Model Steel 认领 引用 被引量：9
3
作者 Liu FENG Bangxin ZHOU +1 位作者 Jianchao PENG Junan WANG 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2013年第6期707-712,共6页
The crystal structure evolution of the Cu-rich nano precipitates from bcc to 9R during thermal aging was studied in nuclear reactor pressure vessel （RPV） model steels. The specimens, contained higher copper and nick... The crystal structure evolution of the Cu-rich nano precipitates from bcc to 9R during thermal aging was studied in nuclear reactor pressure vessel （RPV） model steels. The specimens, contained higher copper and nickel contents than commercially available one, were heated at 890 ~C for 0.5 h and then water quenched followed by tempering at 0（50 ~C for I0 h and aging at 400 ~C for 1000 h. It was observed that bcc and 9R orthogonal structure, as well as 9R orthogonal and 9R monoclinic structure, coexist in a single Cu-rich nano precipitate. Further analyses pointed out that Cu-rich nano precipitates of bcc structure were not stable, it may preferentially transform to 9R orthogonal structure and then to 9R monoclinic structure. This results showed that the crystal structure evolution of the Cu-rich nano precipitates was complex. 展开更多
关键词 Reactor pressure vessel model steel Thermal aging Cu-rich nano precip-itates Structure evolution HRTEM
暂未订购 下载PDF
Surface structure evolution of cathode materials for Li-ion batteries 认领 引用 被引量：3
4
作者 吕迎春 刘亚利 谷林 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第1期106-114,共9页
Lithium ion batteries are important electrochemical energy storage devices for consumer electronics and the most promising candidates for electrical/hybrid vehicles. The surface chemistry influences the performance of... Lithium ion batteries are important electrochemical energy storage devices for consumer electronics and the most promising candidates for electrical/hybrid vehicles. The surface chemistry influences the performance of the batteries significantly. In this short review, the ewlution of the surface struture of the cathode materials at different states of the pristine, storage and electrochemical reaclions are summarized. The main methods for the surface modification are also introduced. 展开更多
关键词 structure evolution surface cathode Li-ion batteries
暂未订购 下载PDF
Effects of compressing and remelting in SIMA processing on semi-solid structure evolution of an Al-Zn wrought alloy 认领 引用 被引量：6
5
作者 LIUChangming ZOUMaohua 《Rare Metals》 SCIE EI CAS 2003年第3期185-191,共7页
Structure evolution of an Al-Zn wrought alloy in remelting processing in thestrain induced melt activated (SIMA) serai-solid procedure was observed, and effects of factors, theremelting temperature, the holding time, ... Structure evolution of an Al-Zn wrought alloy in remelting processing in thestrain induced melt activated (SIMA) serai-solid procedure was observed, and effects of factors, theremelting temperature, the holding time, and the compression strain, on structures and grain sizesof the alloy were investigated. The results show that (1) the proper temperature of remelting is inthe range of 610 to 615℃; (2) the grain size in specimen with greater compression strain is smallerthan that with smaller compression strain in condition of the same remelting temperature andholding time, and the grain size in local area with great local equivalent strain is smaller thanthat with small one; (3) liquid occurs in form of cluster in matrix during remelting and itsquantity increases with remelting time increasing; liquid in specimen with great compression strainoccurs earlier than that with small one, and quantity of liquid in the center of specimen withgreater local equivalent strain is greater than that in the two ends of it; (4) distortion energyafter deforming in matrix of the alloy is the significant factor to activate melting of matrix atlocal area with great local equivalent strain. 展开更多
关键词 semi-solid structure evolution strain induced melt activated processing semi-solid remelting Al-Zn alloy
暂未订购 下载PDF
Densification and Structure Evolution of ZrB2-ZrO2 Composites Prepared by Plasma Activated Sintering using ZrB2@ZrO2 Powder 认领 引用 被引量：1
6
作者 YANG Haitao ZHANG Jian +1 位作者 LI Junguo SHEN Qiang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2021年第2期215-222,共8页
The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB2-ZrO2 composite via the ZrO2-coated ZrB2 powder(ZrB2@ZrO2)prepared by in situ passivation method were i... The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB2-ZrO2 composite via the ZrO2-coated ZrB2 powder(ZrB2@ZrO2)prepared by in situ passivation method were investigated.The composition and microstructure were characterized by XRD,Raman,SEM,and EDS techniques.The coated powder has excellent sintering performance.The relative density of the composite reaches above 90%at 1200℃,and the main sintering process occurs between ZrO2 particles.While at above 1500℃,the relative density reaches above 95%and the main sintering process occurs between ZrB2 and ZrO2 particles.With the increase of ZrO2 coating content,the structure of the sintered body changes from ZrB2 continuous network structure to island structure.When the content is 20%,an island structure is formed.Increasing the ZrO2 content further causes the overheating of ZrO2.Thus,the best sintering performance reaches when the coating content is 20wt%. 展开更多
关键词 ZrB2 ZrO2 coating content densification structure evolution
暂未订购 下载PDF
Structure Evolution of Bulk Metallic Glass Zr52.5Ni14.6Al_10Cu17.9Ti_5 during Annealing 认领 引用 被引量：1
7
作者 Guo HE, Zan BIAN and Guoliang CHEN 《Journal of Materials Science & Technology》 SCIE EI CAS 2000年第4期357-361,共5页
Bulk metallic glass Zr_52.5Ni_14.6Al_10Cu_17.9Ti_5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be ... Bulk metallic glass Zr_52.5Ni_14.6Al_10Cu_17.9Ti_5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be 631 K and 710 K respectively. By analysis of X-ray diffractometry (XRD) and transmission electron microscopy (TEM ), the predominant crystallized phase of Zr_2Ni0.67O0.33 distributed on glass state matrix was detected after annealing at 673 K for 600 s. The transformation to Zr_2Ni_0.67O_0.33 and a small amount of ZrAl and Zr_2Cu took place after annealing for 600 s at temperature from 703 K to 723 K. With increasing annealing temperature from 753 K to 823 K, the amounts of ZrAl and Zr_2Cu increased, but the size of the crystals did not significantly change. The transformation to Zr_2Ni_0.67O_0.33 is interface-controlled, but is diffusion-controlled to Zr_2Cu and ZrAl. With increasing annealing temperature up to 200 K above T_x, the nanometer grains became very fine because of the increase of nucleation rate for Zr_2Cu and ZrAl. 展开更多
关键词 Structure Evolution of Bulk Metallic Glass Zr Ti5 during Annealing Al10Cu Ni Cu
暂未订购 下载PDF
In-situ observation and analysis of solidified structure evolution of S50C steel in soaking furnace 认领 引用
8
作者 Kai Liu Shu-sen Cheng +4 位作者 Xing-wen Wei Wen-xuan Xu Ji-peng Li Yong-ping Feng Olena Volkova 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2023年第10期1963-1973,共11页
The evolution of solidified structure of S50C steel during heat treatment in compact strip production process was studied through an ultra-high-temperature confocal scanning laser microscope.It was found that the soli... The evolution of solidified structure of S50C steel during heat treatment in compact strip production process was studied through an ultra-high-temperature confocal scanning laser microscope.It was found that the solidified structure consisted of dendritic crystals with secondary dendrite arm spacing ranging in 32-120μm,where carbon segregation was evident,and the dendrite arms wereα-Fe.The insignificant change was observed at a soaking temperature of 1180℃,whereas at 1300℃,the finer structure firstly disappeared,and then,the coarsening decreased,indicating that carbon tended to be homogenized.Therefore,the microsegregation was improved at 1300℃for 15 min.The phase transformation ofα-Fe→γ-Fe enhanced the carbon diffusion,and the evolution of the equivalent radius req was controlled by carbon diffusion.The diffusion coefficient of carbon(D=15μm2/s)was determined by using the inverse problem method. 展开更多
关键词 Compact strip production process Solidified structure evolution Carbon diffusivity Inverse problem method
暂未订购 下载PDF
Microstructure Evolution of a Cold-rolled 25Cr-7Ni-3Mo-0.2N Duplex Stainless Steel during Two-step Aging Treatments 认领 引用 被引量：3
9
作者 Tian LIANG Xiaoqiang HU +1 位作者 Xiuhong KANG Dianzhong LI 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2013年第5期517-522,共6页
A cold-rolled 25Cr-7Ni-3Mo-0.2N duplex stainless steel（DSS） has been aged in two steps. Firstly, the aging treatment at interval of 50℃ in a temperature range from 900 to 1050℃ was carried out in order to obtain f... A cold-rolled 25Cr-7Ni-3Mo-0.2N duplex stainless steel（DSS） has been aged in two steps. Firstly, the aging treatment at interval of 50℃ in a temperature range from 900 to 1050℃ was carried out in order to obtain fine grains. Secondly, another aging treatment at 850℃ was performed to reveal the σ-phase precipitation behavior. A detailed microstructure evolution during those two aging steps was observed by the optical microscope（OM）, the scanning electron microscope（SEM）, the electron backscatter difraction（EBSD） and the transmission electron microscope（TEM）. The results revealed that the micro-duplex structure with grain size of lower than 10 μm appeared after the first aging step. However, their grain size was rapidly increased with increasing aging temperature. Meanwhile, the δ → γ and/or δ → γ ＋ σ transformations took place in association with the occurrence of the extensive recovery or a little recrystallization in δ-grains. During the second aging treatment, σ-phase mainly nucleated at δ/γ interfaces and further grew along those interfaces into various morphologies（e.g., butterfly and granule）. A novel precipitation behavior was found in this study that the γ-grain boundaries bulged not only into the δ-grains as usual, but abnormally into the σ-phase precipitates without the prior precipitation of the isolated secondary austenite γ2or another phases. 展开更多
关键词 Duplex stainless steel Microstructure evolution Sigma phase Aging treatment Micro-duplex structure
暂未订购 下载PDF
Mineralogical characteristics,metallurgical properties and phase structure evolution of Ca-rich hematite sintering 认领 引用 被引量：2
10
作者 Lele Niu Zhengjian Liu +4 位作者 Jianliang Zhang Dawei Lan Sida Li Zhen Li Yaozu Wang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第2期303-313,共11页
In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical prope... In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO3) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m2·h),6.11 kg,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species. 展开更多
关键词 calcium-rich iron ore mineralogical properties phase structure evolution flue gas heat grey relation analysis
暂未订购 下载PDF
Structure evolution of oxygen removal from porous carbon for optimizing supercapacitor performance 认领 引用 被引量：18
11
作者 Siting Yuan Xianhong Huang +5 位作者 Hao Wang Lijing Xie Jiayao Cheng Qingqiang Kong Guohua Sun Cheng-Meng Chen 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2020年第12期396-404,共9页
The presence of oxygen functional groups is detrimental to the capacitive performance of porous carbon electrode in organic electrolyte. In this regards, hydrogen thermal reduction has been demonstrated effective appr... The presence of oxygen functional groups is detrimental to the capacitive performance of porous carbon electrode in organic electrolyte. In this regards, hydrogen thermal reduction has been demonstrated effective approach in removing the unstable surface oxygen while maintaining the high porosity of carbon matrix. However, the exact evolution mechanism of various oxygen species during this process, as well as the correlation with electrochemical properties, is still under development. Herein, biomass-based porous carbon is adopted as the model material to trace its structure evolution of oxygen removal under hydrogen thermal reduction process with the temperature range of 400–800 °C. The optimum microstructure with low oxygen content of 0.90% and proper pore size distribution was achieved at 700°C. XPS, TPRMS and Boehm titration results indicate that the oxygen elimination undergoes three distinctive stages(intermolecular dehydration, hydrogenation and decomposition reactions). The optimum microstructure with low oxygen content of 0.90% and proper pore size distribution was achieved at 700 °C. Benefiting from the stable electrochemical interface and the optimized porous structure, the as-obtained HAC-700 exhibit significantly suppressed self-discharge and leak current, with improved cycling stability, which is attributable to the stabilization of electrochemical interface between carbon surface and electrolyte. The result provides insights for rational design of surface chemistry for high-performance carbon electrode towards advanced energy storage. 展开更多
关键词 Starch-based activated carbon Oxygen functional groups Hydrogen thermal reduction Structural evolution Organic electrolytes Electrochemistry
暂未订购 下载PDF
Insight into structure evolution of carbon nitrides and its energy conversion as luminescence 认领 引用 被引量：4
12
作者 Hao Zhang Jingwei Zhang +4 位作者 Wenjie Chen Minjia Tao Xianguang Meng Yuanjian Zhang Guifu Zuo 《Carbon Energy》 SCIE EI CAS CSCD 2024年第2期37-60,共24页
A series of carbon nitride(CN)materials represented by graphitic carbon nitride(g-C3N4)have been widely used in bioimaging,biosensing,and other fields in recent years due to their nontoxicity,low cost,and high l... A series of carbon nitride(CN)materials represented by graphitic carbon nitride(g-C3N4)have been widely used in bioimaging,biosensing,and other fields in recent years due to their nontoxicity,low cost,and high luminescent quantum efficiency.What is more attractive is that the luminescent properties such as wavelength and intensity can be regulated by controlling the structure at the molecular level.Hence,it is time to summarize the related research on CN structural evolution and make a prospect on future developments.In this review,we first summarize the research history and multiple structural evolution of CN.Then,the progress of improving the luminescence performance of CN through structural evolution was discussed.Significantly,the relationship between CN structure evolution and energy conversion in the forms of photoluminescence,chemiluminescence,and electrochemiluminescence was reviewed.Finally,key challenges and opportunities such as nanoscale dispersion strategy,luminous efficiency improving methods,standardization evaluation,and macroscopic preparation of CN are highlighted. 展开更多
关键词 carbon nitride chemiluminescence electrochemiluminescence energy conversion photoluminescence structural evolution
暂未订购 下载PDF
Local atomic structure evolution of liquid gadolinium and yttrium during solidification:An ab initio study 认领 引用
13
作者 Qinghe Zheng Tao Hu +6 位作者 Sébastien Le Roux Musen Li Chaoyue Chen Jianbo Yu Jiang Wang Wei Ren Zhongming Ren 《Journal of Rare Earths》 SCIE EI CAS CSCD 2023年第8期1265-1271,I0006,共7页
Local atomic structure evolution of pure gadolinium(Gd)and yttrium(Y)during solidification was investigated by using ab initio molecular dynamics(AIMD)simulation.The calculated results indicate that the local short-ra... Local atomic structure evolution of pure gadolinium(Gd)and yttrium(Y)during solidification was investigated by using ab initio molecular dynamics(AIMD)simulation.The calculated results indicate that the local short-range order(SRO)in liquid Gd and Y is similar to some transitional metals with an asymmetric shape of the second peak in static structure factors.Moreover,the formation of icosahedral local motifs as a function of temperature decreases the diffusivity,which explains the connection between structure evolution and dynamic properties.In examining the topological structures of both systems,we demonstrate that small atomic displacement leads to two different types of topological sixfold rings in liquid and solid states.All analyses yield a systematic study about rare earth metals Gd and Y at the atomic level. 展开更多
关键词 Atomic structure evolution Rare earth Ab initio molecular dynamics Solidification
暂未订购 下载PDF
Studies of Structure Evolution of Nanostructured Hf11Ni89 Alloy 认领 引用
14
作者 Zhenfu DONG and Lianmao PENGKe LU and Zhuangqi HU(State Key Lab. for RSA, Institute of Meta 《Journal of Materials Science & Technology》 SCIE EI CAS 1998年第3期205-210,共6页
A nanostructured Hf11Ni89 ribbon sample was prepared by melt-spinning. It was found that the as-quenched sample is composed of a major HfNi5 compound nanophase and an interfacial magnetic Ni(Hf) solid solution phase. ... A nanostructured Hf11Ni89 ribbon sample was prepared by melt-spinning. It was found that the as-quenched sample is composed of a major HfNi5 compound nanophase and an interfacial magnetic Ni(Hf) solid solution phase. The structure evolution of the sample was studied by using X-ray difFraction (XRD), transmission electron microscopy (TEM), difFerential scanning calorimetry (DSC), resistivity and magnetothermal analysis. Upon heating, a second precipitation process of the Ni(Hf) phase prior to grain growth wa5 detected by means of both structural analysis and physical property measurements. The measurement results are discussed based on the relationship between microstructure and physical properties. 展开更多
关键词 Studies of Structure Evolution of Nanostructured Hf Alloy Ni
暂未订购 下载PDF
Structure Evolution Mechanism of Poly(acrylonitrile/itaconic acid/acrylamide) during Thermal Oxidative Stabilization Process 认领 引用 被引量：3
15
作者 zhao-po zeng ze-chun shao +1 位作者 肖茹 yong-gen lu 《Chinese Journal of Polymer Science》 SCIE EI CAS CSCD 2017年第8期1020-1034,共15页
Polyacrylonitrile （PAN） polymers with different compositions were prepared by an efficient aqueous free-radical polymerization technique. Thermal properties of polyacrylonitrile homopolymer （PAN）, poly（acrylonitr... Polyacrylonitrile （PAN） polymers with different compositions were prepared by an efficient aqueous free-radical polymerization technique. Thermal properties of polyacrylonitrile homopolymer （PAN）, poly（acrylonitrile/itaconic acid） [P（AN/IA）] and poly（acrylonitrile/itaconic acid/acrylamide） [P（AN/IA/AM）] were studied by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetry in detail. It was found that AM had the ability to initiate and accelerate thermal oxidative stabilization process, which was confirmed by the lower initiation temperature and broader exothermic peak in P（AN/IA/AM） as compared with that in P（AN/IA） and PAN. The intensity of heat releasing during the thermal treatment was relaxed due to the presence of two separated exothermic peaks. Accompanied by DSC analysis and calculation of the apparent activation energy of cyclization reaction, two peaks were assigned to the ionic and free radical induction mechanisms, respectively. The higher rate constant in P（AN/IA/AM） indicated that the ionic mechanism actually had a kinetic advantage at promoting thermal stability over the free radical mechanism. This study clearly show that the synthesized P（AN/IA/AM） terpolymers possess larger room to adjust manufacture parameters to fabricate high performance of PAN-based carbon fibers. 展开更多
关键词 PAN terpolymers Structural evolution Thermal oxidative stabilization Thermal analysis Kinetics
暂未订购 下载PDF
Structure Evolution of China Aviation Network Based on Hierarchical Model 认领 引用
16
作者 Cheng Xiangjun Chen Xumei Li Tao 《Journal of Traffic and Transportation Engineering》 2022年第3期95-103,共9页
The annual passenger volume of airport reflected its passenger transport scale and the role in aviation network.The airports in whole country were divided into three layers:first layer airports,second layer airports a... The annual passenger volume of airport reflected its passenger transport scale and the role in aviation network.The airports in whole country were divided into three layers:first layer airports,second layer airports and third layer airports.The airlines from the first layer airports consisted the first layer aviation network.The airlines from the second layer airports consisted the second layer aviation network.The airlines from the third layer airports consisted the third layer aviation network.The structure and function of different layer aviation network had significant differences.These differences were shown in the number of airlines,average number of airlines of each airport,annual passenger volume of airport and average passenger volume of each airline.National aviation network hierarchical model was constructed to describe the whole country aviation network.The matrix was built to describe the airline number,annual passenger volume,average number of airlines,average passenger volume of each airport and airline rate of aviation network.The index of national aviation network structure was constructed to show the ratio of index between different aviation network layer to describe the aviation network structure.The structure index was built to illustrate the macrostructural features of national aviation network.The statistics data in year 1988,1994,2001,2008 and 2015 of China aviation network were analyzed and basic data matrixes,basic index matrixes and structure index matrixes were calculated.The trend of ratio of corresponding index between the first layer and the second layer showed the change of basic structure of China aviation network.At meantime,the tendency of ratio of corresponding index between the third layer and the second layer also showed the change of basic structure.The trend of network general structure index illustrated that the large scaled new airports and airlines construction had significant influence on the national aviation network structure. 展开更多
关键词 National aviation network structure evolution hierarchical model structure index matrix
暂未订购 下载PDF
Structure Evolution of Intense Arctic Cyclones in August 2016 认领 引用
17
作者 Yao YAO Wei ZHONG +1 位作者 Xiu-Qun YANG Qian QIAN 《Journal of Meteorological Research》 SCIE CSCD 2026年第1期156-172,共17页
Arctic cyclones(ACs)are the major hazardous weather systems affecting the Arctic.Intense AC activity induces strong near-surface wind,high ocean wave,and heavy precipitation,causing dramatic environmental and socioeco... Arctic cyclones(ACs)are the major hazardous weather systems affecting the Arctic.Intense AC activity induces strong near-surface wind,high ocean wave,and heavy precipitation,causing dramatic environmental and socioeconomic impacts.Whether an AC can develop into an intense one is closely related to its structure evolution.Previous studies generally considered that intense summer ACs are characterized by a shift from a baroclinic structure to a barotropic structure around the maximum intensity time.This study investigates the structure evolution of two intense ACs in August 2016.The results indicate that both ACs exhibited similar structure evolution characteristics:ACs underwent two distinct structural transitions,in which a unique transitional structure is identified between the baroclinic structure and the barotropic structure.During the developing stage,ACs featured an asymmetric baroclinic structure,with its central axis tilting towards cold anomalies.The relative vorticity was high along the warm and cold fronts,with the shallow cyclonic circulation in the lower and middle troposphere.During the mature stage,as the tropopause polar vortex(TPV)caught up to ACs,ACs experienced the first structural transition from the baroclinic structure to a transitional structure.With a tropopause fold descending down to 600 h Pa over the cyclone center,ACs developed into a deep cyclonic circulation extending from the troposphere to the lower stratosphere.While a warm core related to the TPV dominated in the lower stratosphere,ACs maintained the baroclinic structure in the troposphere,with the decreased tilt of the axis.During the decay stage,ACs underwent the second structural transition from the transitional structure to an axisymmetric barotropic structure,with a cold core throughout the troposphere and a warm core in the lower stratosphere.These results may have implications for advancing the understanding of the structure evolution and intensification mechanisms of intense summer ACs. 展开更多
关键词 arctic cyclone structure evolution transitional structure tropopause polar vortex
Structure evolution of cubic boron nitride under spark plasma sintering 认领 引用
18
作者 Zhao Yucheng Wang Mingzhi 《金刚石与磨料磨具工程》 CAS 北大核心 2008年第S1期165-167,共3页
Cubic boron nitride(CBN)micro powders and mixture of CBN micro powders with Al or Ti powders were fast heated at 1300,1400,1450,1500℃,and then kept for 5 min under spark plasma sintering(SPS).The obtained powders wer... Cubic boron nitride(CBN)micro powders and mixture of CBN micro powders with Al or Ti powders were fast heated at 1300,1400,1450,1500℃,and then kept for 5 min under spark plasma sintering(SPS).The obtained powders were analyzed with XRD.The results show that,simple CBN kept cubic structure after heated at 1300℃;when the temperature rose to 1400℃,some CBN was transformed into hexagonal structured boron nitride(hBN).As for CBN micro powders mixed with aluminum or titanium micro powders,the onset transforming temperature of CBN to hBN get raised.This results indicated that the structural transformation of boron nitride begun from the surface of CBN crystal particle,different coexist elements affect the surface situation of CBN particles.As the stabilities of CBN crystal particle surface improved,the onset structural transform temperature of CBN was also increased. 展开更多
关键词 cubic boron nitride structure evolution transformation spark plasma sintering(SPS)
暂未订购 下载PDF
Reconstruction of pore structure and transformation of failure mode in reef limestone under MICP grouting 认领 引用
19
作者 Wenxi Zhu Huafeng Deng +5 位作者 Linjian Ma Mingyang Wang Yao Xiao Hongya Li Lei Cheng Wenlong Yu 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2026年第4期793-810,共18页
Given the high porosity,strong connectivity,and low strength of reef limestone,microbial-induced carbonate precipitation(MICP) reinforcement tests were performed under different grouting cycles.CTbased three-dimension... Given the high porosity,strong connectivity,and low strength of reef limestone,microbial-induced carbonate precipitation(MICP) reinforcement tests were performed under different grouting cycles.CTbased three-dimensional reconstruction,uniaxial compression,and acoustic emission analyses were employed to elucidate the coupling mechanism between microstructural evolution and macroscopic mechanical behavior.MICP-induced calcium carbonate deposition exhibited distinct scale selectivity,initially occurring in large pores and highly coordinated nodes,which reduced the average pore diameter from 221.26 μm to 75.36 μm and transformed the pore network from a highly connected loose type to a dense isolated one.The elastic modulus increased from 3.27 GPa to 6.21 GPa,and the peak strength approximately doubled,while the failure mode evolved from brittle to brittle–ductile.Acoustic emission analysis revealed a greater proportion of post-peak high-energy events and a frequency shift from high to mid–low ranges,indicating a multi-stage energy dissipation process.A reinforcement variable was introduced to quantify the MICP-induced strengthening,and a structural densification factor was incorporated to establish a constitutive model governed by densification.The study clarifies the coupling mechanism from microscopic densification to macroscopic enhancement,providing theoretical support for the green reinforcement of highly porous rock masses. 展开更多
关键词 Reef limestone MICP Pore structure evolution Grouting cycles Reinforcement variable
暂未订购 下载PDF
Structure and property evolution of atomically precise palladium clusters 认领 引用
20
作者 Chang-Qing Meng Wan-Yu Cheng +6 位作者 Hao Yan Hui-Xin Xiang Chen-Hao Ruan Yue Zhao Cong-Qiao Xu Jun Li Chuan-Hao Yao 《Rare Metals》 SCIE EI CAS CSCD 2025年第4期2822-2829,共8页
Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clus... Atomically precise palladium(Pd)clusters are emerging as versatile nanomaterials with applications in catalysis and biomedicine.This study explores the synthesis,structure evolution,and catalytic properties of Pd clusters stabilized by cyclohexanethiol(HSC6H11)ligands.Using electrospray ionization mass spectrometry(ESI-MS)and single-crystal X-ray diffraction(SXRD),structures of the Pd clusters ranging from Pd4(SC6H11)8 to Pd18(SC6H11)36 were determined.This analysis revealed a structure evolution from polygonal to elliptical geometries of the PdnS2n frameworks as the cluster size increased.UV-Vis-NIR spectroscopy,combined with quantum chemical calculations,elucidated changes in the electronic structure of the clusters.Catalytic studies on the Sonogashira cross-coupling reactions demonstrated a size-dependent decline in activity attributed to variations in structural arrangements and electronic properties.Mechanistic insights proposed a distinctive Pd(Ⅱ)-Pd(Ⅳ)catalytic cycle.This research underscores how ligands and cluster size influence the structures and properties of Pd clusters,offering valuable insights for the future design and application of Pd clusters in advanced catalysis and beyond. 展开更多
关键词 structure evolution catalytic properties quantum chemical calculations cyclohexanethiol ligands electrospray ionization mass spectrometry esi ms atomically precise palladium clusters sonogashira cross coupling reactions electronic structure
暂未订购 下载PDF
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
上一页 1 2 … 13 下一页 到第 页
在线咨询 使用帮助 返回顶部 意见反馈