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A comparative investigation of an AB- and AA-stacked bilayer graphene sheet under an applied electric field:A density functional theory study 被引量:1
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作者 汪涛 郭清 +1 位作者 刘艳 盛况 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期451-455,共5页
An AB-and AA-stacked bilayer graphene sheet (BLG) under an electric field is investigated by ab initio calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system a... An AB-and AA-stacked bilayer graphene sheet (BLG) under an electric field is investigated by ab initio calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system are investigated in the presence of different electric fields normal to the BLG. The AB-stacked BLG is able to tune the bandgap into 0.234 eV with the increase of the external electronic field to 1 V/nm, however, the AA-stacked BLG is not sensitive to the external electric field. In both the cases, the spacing between the BLG slightly change in terms of the electric field. The charges in the AB-stacked BLG are increased with the increase of the electric field, which is considered to be the reason that causes the bandgap opening in the AB-stacked BLG. 展开更多
关键词 GRAPHENE bandgap density functional theory study
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Using of Key Stratum Theory to Study the Structural Development of Roof Aquifer 被引量:2
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作者 CHEN Li ZHANG Fawang +4 位作者 YAO Hongchao HAN Zhantao QIAN Long CHEN Liang JIANG Chengchao 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2015年第6期2091-2091,共1页
During the underground mining of coal resources,overlying rocks on the roof of excavated tunnels will be destroyed due to ground pressure,and as a result,part of them will break and fall into the tunnels.How to determ... During the underground mining of coal resources,overlying rocks on the roof of excavated tunnels will be destroyed due to ground pressure,and as a result,part of them will break and fall into the tunnels.How to determine the distribution of fractured areas and fissures presents a major problem for preserving the overlying aquifer. 展开更多
关键词 In Using of Key Stratum Theory to study the Structural Development of Roof Aquifer
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Study of Polymer Blends with Sub-cluster Theory PartⅠ Essential Concepts and Equations of Sub-cluster Theory 被引量:2
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作者 Riguang JIN and Hangquan LI (Beijing Institute of Chemical Technology, Beijing, 100029, China)(To whom correspondence should be addressed) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1994年第2期111-116,共6页
Various viscosity-composition curves of polymer blends are summarized in eight groups. To represent these curves. 'sub-cluster equations' are derived on the basis of so called 'sub-cluster theoryThe essent... Various viscosity-composition curves of polymer blends are summarized in eight groups. To represent these curves. 'sub-cluster equations' are derived on the basis of so called 'sub-cluster theoryThe essential concepts of sub-cluster theory and the derivation of those 'Sub-cluster equations' are briefly introduced. 展开更多
关键词 Essential Concepts and Equations of Sub-cluster Theory study of Polymer Blends with Sub-cluster Theory Part
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The Theory Study of the Influence of the Topography on the Cold Frontal Motion 被引量:1
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作者 顾伟 伍荣生 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1992年第2期167-172,共6页
In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exis... In order to study the characteristics of cold frontal motion over the arbitrary topography, the velocity of cold frontal movement is derived by using the one layer shallow-water model. The results show that there exist the retardation in upwind side and rapid descent in the lee slope when the cold front crosses the topography. 展开更多
关键词 In The Theory study of the Influence of the Topography on the Cold Frontal Motion
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A PRELIMINARY STUDY ON THE THEORY OF THE SECOND AND THIRD ORDER DERIVATIVE ADSORPTION CHRONOPOTENTIOMETRY FOR A REVERSIBLE REACTION
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作者 Hong Guang ZHANG Wen Rui JIN Department of Chemistry,Shandong University,Jinan,250100,ShandongFu Song HUANG Department of Computer Science,Shandong University,Jinan,250100,Shandong 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第3期257-258,共2页
The equations of the second and third order derivative curves of time with respect to potential for a reversible process in adsorption chronopotentiometry are derived and experimentally verified.
关键词 In RT A PRELIMINARY study ON THE THEORY OF THE SECOND AND THIRD ORDER DERIVATIVE ADSORPTION CHRONOPOTENTIOMETRY FOR A REVERSIBLE REACTION
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Study of Polymer Blends with Sub-cluster Theory Part 2 Comparison of PVC/ABS, PVC/SBS Blends
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作者 Riguarng JIN and Hangquan LI(Bejing Institute of Chemical Technology, Beijing, 100029, China) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1994年第3期181-187,共7页
Series of PVC/ABS and PVC/SBS blends of composition 20/ 80. 40/ 60, 60 / 40 and 80 / 20were prepared in a screw extruder. The phase morphology, miscibility and rheological behaviour of two systems were investigated. T... Series of PVC/ABS and PVC/SBS blends of composition 20/ 80. 40/ 60, 60 / 40 and 80 / 20were prepared in a screw extruder. The phase morphology, miscibility and rheological behaviour of two systems were investigated. The viscosity-composition plots were represented by sub-cluster equation, the various differences between two systems are interpreted with the equation parameters 展开更多
关键词 PVC/SBS Blends SBS study of Polymer Blends with Sub-cluster Theory Part 2 Comparison of PVC/ABS
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Theory Study on Teachers' Happiness Degree in Private Colleges
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作者 Zhu Jingsi Zhao Yonglin 《International English Education Research》 2015年第4期42-44,共3页
Based on analyzing actual cases and referring to other discourses, this discourse analyzes the happiness of teachers in non-governmental funded universities from three perspectives: the subjectivity of "happiness",... Based on analyzing actual cases and referring to other discourses, this discourse analyzes the happiness of teachers in non-governmental funded universities from three perspectives: the subjectivity of "happiness", psychological condition and the influence of career. As a result, this discourse can find tools for evaluating happiness and use them to evaluate the degree of happiness in non-governmental funded universities. 展开更多
关键词 the private colleges Teachers' degree of happiness theory study
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Anderson's Cognitive Theory and Learning Strategy Studies in Second Language Acquisition 被引量:9
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作者 Lu Wenpeng (Foreign Languages department, Northwest Normal University, Lanzhou, 730070, China) 《兰州大学学报(社会科学版)》 CSSCI 北大核心 2000年第S1期228-231,共4页
Second language acquisition can not be understood without addressing the interaction between language and cognition. Cognitive theory can extend to describe learning strategies as complex cognitive skills. Theoretical... Second language acquisition can not be understood without addressing the interaction between language and cognition. Cognitive theory can extend to describe learning strategies as complex cognitive skills. Theoretical developments in Anderson’s production systems cover a broader range of behavior than other theories, including comprehension and production of oral and written texts as well as comprehension, problem solving, and verbal learning.Thus Anderson’s cognitive theory can be served as a rationale for learning strategy studies in second language acquisition. 展开更多
关键词 Anderson’s cognitive theory Anderson’s production systems learning strategy studies second language acquisition
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Theoretical study on the formation mechanism of polychlorinated dibenzothiophenes/thianthrenes from 2-chlorothiophenol molecules 被引量:1
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作者 Xiaoqing Yu Jiamin Chang +2 位作者 Xian Liu Wenxiao Pan Aiqian Zhang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2018年第4期318-327,共10页
Homogeneous formation of polychlorinated dibenzothiophenes/thianthrenes(PCDT/TAs),sulfurated compounds analogous to polychlorinated dibenzo-p-dioxin/dibenzofurans(PCDD/Fs), has been well-documented to occur via ra... Homogeneous formation of polychlorinated dibenzothiophenes/thianthrenes(PCDT/TAs),sulfurated compounds analogous to polychlorinated dibenzo-p-dioxin/dibenzofurans(PCDD/Fs), has been well-documented to occur via radical–radical coupling reactions from chlorinated thiophenol precursors. However, the current understanding of the formation mechanism of PCDT/TAs is exclusively limited to the inherent point of view that chlorothiophenoxy radicals act as the only required intermediates for PCDT/TAs. This study investigates reaction pathways for the formation of PCDT/TAs involving two new types of radical species, i.e., substituted phenyl radicals and substituted thiophenoxyl diradicals. Taking 2-chlorothiophenol(2-CTP) as a model compound for chlorothiophenols,we found that apart from the mostly discussed chlorothiophenoxy radicals, substituted phenyl radicals and substituted thiophenoxyl diradicals could also be readily formed via the reaction of 2-CTP with H radicals. Furthermore, direct self-and cross-coupling of these radicals can result in the formation of PCDT/TAs, including 1-monochlorothianthrene(1-MCTA), 1,6-dichlorothianthrene(1,6-DCTA), 4,6-dichlorodibenzothiophene(4,6-DCDT)and 1,6-dichlorodibenzothiophene(1,6-DCDT). The pathways proposed in this work are proven to be both thermodynamically and kinetically favorable. Particularly, comparisons were made between the formation mechanisms of sulfurated and oxygenated dioxin systems from an energetic point view, showing that replacing oxygen with sulfur atoms greatly reduces the activation barriers of the rate-controlling steps involved in the PCDT/TA formation processes compared with those involved for PCDD/Fs. The calculated results in this work may improve our understanding of the formation mechanism of PCDT/TAs from chlorothiophenol precursors and should be informative to environmental scientists. 展开更多
关键词 Polychlorinated dibenzothiophenes/thianthrenes Formation mechanism Phenyl radicals Thiophenoxyl diradicals Density functional theory study
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A STUDY ON THE LOW SPEED SHIP THEORY
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作者 Wu Jian-hua Li Shi-mo Wuhan Institute of water Transportation Engineering,Wuhan,P.R.China 《Journal of Hydrodynamics》 SCIE EI CSCD 1989年第2期45-54,共10页
Based on Baba's assumption,the linearized free-surface boundary conditions at low speed are discussed in order to demonstrate the differences between Baba's and Dawson's free-surface boundary conditions.By... Based on Baba's assumption,the linearized free-surface boundary conditions at low speed are discussed in order to demonstrate the differences between Baba's and Dawson's free-surface boundary conditions.By using Fourier integral transfor- mation,a method of computing wave velocity potential ,which satisfies the boundary conditions of free-surface and hull surface,is presented.The solution of is found with the powerful technique of asymptotic expansions.With order comparison method,it is found that the hull surface boundary conditions can be neglected when only the ship wave resistance is concerned.The exact analytical solution of two-dimensional slow ship wave velocity potential is derived by neg- lecting hull effect.The results show that the inhomogeneous effect of free-surface is not negligible in the boundary value problems of slow ship velocity potential. 展开更多
关键词 WAVE exp A study ON THE LOW SPEED SHIP THEORY
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Variational transition state theory study of the reactions Li+HF and Li+HCl on the BO potential energy surfaces
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作者 YANG Yu-Wei JU Guan-Zhi DENG Cong-Hao 《Chinese Journal of Chemistry》 SCIE CAS CSCD 1991年第5期393-398,共0页
Variational transition state theory is used to study the kinetics of the reactions Li+HF and Li+HCl on the BO potential energy surfaces, fitted to ab initio values by Lagana et al. The saddle point, the location of ge... Variational transition state theory is used to study the kinetics of the reactions Li+HF and Li+HCl on the BO potential energy surfaces, fitted to ab initio values by Lagana et al. The saddle point, the location of generalized transition state and other kinetic features on the bottleneck of the po- tential energy surface are obtained. We point out that the location of generalized transition state tends to the direction in which the two atoms with larger reduced mass separate off. It can be determined whether a potential energy surface is accurate or not by a fine analysis of its bottleneck region and a comparison of kinetic calculation with experimental result. This is helpful for building a more accurate potential energy surface. 展开更多
关键词 Li Variational transition state theory study of the reactions Li+HF and Li+HCl on the BO potential energy surfaces BO CVT HF HCI HCL
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A pH-universal ORR catalyst with atomic Fe-heteroatom(N,S)sites for high-performance Zn-air batteries 被引量:1
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作者 Le Li Na Li +6 位作者 Jia-Wei Xia Shi-Long Zhou Xing-Yue Qian Feng-Xiang Yin Guo-Hong Dai Guang-Yu He Hai-Qun Chen 《Nano Research》 SCIE EI CSCD 2023年第7期9416-9425,共10页
Developing innovative,easy-to-manufacture,and non-Pt-group-metal(non-PGM)electrocatalysts is essential for the highly efficient oxygen reduction reaction(ORR).Herein,we report a self-sacrificing post-synthetic strateg... Developing innovative,easy-to-manufacture,and non-Pt-group-metal(non-PGM)electrocatalysts is essential for the highly efficient oxygen reduction reaction(ORR).Herein,we report a self-sacrificing post-synthetic strategy to synthesize highly loaded Fe-isolated single atoms anchored on the hierarchical porous N,S co-doped carbon matrix(Fe-SAs/S,N-C/rGO).The optimized Fe-SAs/S,N-C/rGO exhibits excellent ORR activity in the pH-universal range with half-wave potentials of 0.89,0.80,and 0.60 V in alkaline,acidic,and neutral media,comparable to the commercial Pt/C(0.85,0.81,and 0.64 V,respectively).The homemade liquid Zn-air battery(ZAB)with Fe-SAs/S,N-C/rGO as the cathode catalyst displays an open-circuit voltage(OCV)of~1.61 V,discharging specific capacity of 817.23 mAh·g^(-1),and long-term durability of~1865 cycles,outperforming those of the device with commercial Pt/C+RuO_(2)(1.49 V,657.32 mAh·g^(-1),and~120 cycles,respectively).Intriguingly,the corresponding flexible solidstate ZAB delivers satisfactory OCV,peak power density,foldability,and cycling stability at room temperature,as well as adaptability at a low temperature of -10℃.Besides,density functional theory(DFT)calculation reveals that the atomic FeN_(3)S moieties in Fe-SAs/S,N-C/rGO can cause charge redistribution and lower the binding strength of oxygen-containing intermediates,resulting in accelerated ORR kinetics and optimized catalytic activity.This work provides insights into experimental and theoretical guidance towards non-PGM electrocatalysts for efficient energy conversion. 展开更多
关键词 heteroatom dopant single-atom electrocatalyst FeN_(3)S sites Zn-air battery density functional theory(DFT)study
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Single-atom Fe-N_(5)catalyst for high-performance zinc-air batteries 被引量:1
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作者 Le Li Yin-Juan Chen +8 位作者 Hao-Ran Xing Na Li Jia-Wei Xia Xing-Yue Qian Hui Xu Wei-Zuo Li Feng-Xiang Yin Guang-Yu He Hai-Qun Chen 《Nano Research》 SCIE EI CSCD 2022年第9期8056-8064,共9页
Developing innovative and efficient non-precious-metal-group(non-PMG)electrocatalysts is crucial for the wide use of zinc-air batteries(ZABs).Herein,a single-atom catalyst(termed as Fe-N-C/rGO SAC)with unique five N-c... Developing innovative and efficient non-precious-metal-group(non-PMG)electrocatalysts is crucial for the wide use of zinc-air batteries(ZABs).Herein,a single-atom catalyst(termed as Fe-N-C/rGO SAC)with unique five N-coordinated Fe(Fe-N_(5))centers is prepared by pyrolyzing the composite of zeolitic-imidazolate-frameworks-8(ZIF-8)and graphene oxide(GO).Specifically,the individual Fe site is stabilized by four equatorial and one axial N atoms donated by the N-doped carbon matrix and imidazole ring,respectively,thus forming an asymmetric electron depletion zone over the metal center,which can effectively promote the generation of reactive intermediates and accelerate the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)processes for ZABs.The rechargeable liquid ZAB with Fe-N-C/rGO catalyst exhibits an extremely high energy density(928.25 Wh·kg^(−1)),a remarkable peak power density(107.12 mW·cm^(−2)),and a long cycle life(400 h).Additionally,the corresponding flexible solid-state ZAB displays superior foldability and remarkable cycling stability.This work provides both experimental and theoretical guidance for rational design of non-PMG electrocatalyst-driven ZABs. 展开更多
关键词 N-doped hierarchical porous carbon/rGO composite single-atom electrocatalyst five N-coordinated Fe(Fe-N_(5))singleatom sites zinc-air battery density functional theory(DFT)study
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Selective 3,4-Polymerization Mechanism of Isoprene Catalyzed by Rare Earth Alkyl Complexes
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作者 LIU Ying SUN Cuihong +1 位作者 LI Xiaofang ZHANG Shaowen 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2014年第1期114-118,共5页
The mechanism of selective 3,4-polymerization reaction of isoprene catalyzed by the rare earth lutecium(Ⅲ) alkyl complexes [2,6-Me2Ph-N-CH2-C(CH2SiMe3)=N-PhMe2-2,6]Lu(CH2SiMe3)2(THF)was investigated by means ... The mechanism of selective 3,4-polymerization reaction of isoprene catalyzed by the rare earth lutecium(Ⅲ) alkyl complexes [2,6-Me2Ph-N-CH2-C(CH2SiMe3)=N-PhMe2-2,6]Lu(CH2SiMe3)2(THF)was investigated by means of the M06/sdd method with solvation effects taken into account.The results show that the structure of the catalyst core remained almost unchanged as the isoprene molecules were alternatively inserted into the complex at two opposite sides.The Gibbs free energies of the coordination complexes,transition state and intermediates indicate that all the isoprene molecules prefer to insert into the complex with the 3,4-polymerization selectivity as catalyzed by the catalyst,which is consistent with the experimental observations.It is found that the insertion reaction of each isoprene is exothermic,which comes mainly from the coordination of the isoprene molecule to the lutecium(Ⅲ) atom.The solvation effects were confirmed important in predicting the Gibbs free energies of the present reaction system. 展开更多
关键词 ISOPRENE Polymerization mechanism Density functional theory study Rare earth catalyst
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A Brief Commentary: Promote Theory Studies and Improve Foreign Language Work
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作者 Ren Zhi 《外国语》 CSSCI 北大核心 1994年第4期77-78,共2页
ABriefCommentary:PromoteTheoryStudiesandImproveForeignLanguageWorkRenZhiChina'sforeignlanguagecircleshavebee... ABriefCommentary:PromoteTheoryStudiesandImproveForeignLanguageWorkRenZhiChina'sforeignlanguagecircleshavebeenbusywithacademic... 展开更多
关键词 Promote Theory Studies and Improve Foreign Language Work A Brief Commentary
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