显示条目: 32348-32367 / 166236

    • V(IV)在不同电极上氧化还原动力学研究 

      乔永莲; 许茜; 张杰; 翟玉春; QIAO Yong-lian; XU Qian; ZHANG Jie; ZHAI Yu-chun (厦门大学《电化学》编辑部, 2007-08-28)
      分别以导电塑料集流板、石墨棒、铂片作工作电极,应用循环伏安法和稳态极化法研究V(IV)的阳极氧化动力学过程,计算V(IV)在不同材料电极上的反应动力学参数.结果表明,以导电塑料板作电极,硫酸氧钒有较宽的水稳定区,且析氧电位较高;在石墨电极上,V(V)/V(IV)的交换电流密度较大,表现出较好的可逆性;而在铂电极上,硫酸氧钒更易析氢.
    • V(Ⅳ)/V(Ⅴ)电对在石墨毡与导电塑料复合电极上的反应机理(英文) 

      李晓刚; 黄可龙; 刘素琴; 谭宁; 陈立泉; LI Xiao-gang; HUANG Ke-long; LIUSu-qin; TAN Ning; CHEN Li-quan (厦门大学《电化学》编辑部, 2006-11-28)
      应用循环伏安、极化曲线和交流阻抗等电化学方法研究了V(Ⅳ)/V(Ⅴ)电对在石墨毡复合电极上反应的速控步骤.结果表明,V(Ⅳ)/V(Ⅴ)电对在石墨毡电极上的反应属准可逆过程,且氧化过程包含有后置化学转化步骤;该过程Tafel斜率的实验值为0.124,而理论计算的,以电化学步骤作为控制步骤的Tafel斜率约0.12,两者吻合很好,表明该氧化过程受电化学步骤控制;以等效电路拟合不同极化电位下的交流阻抗,得出该电化学反应阻抗远大于其他阻抗,意味 ...
    • V(Ⅴ)-O团簇上甲烷C-H键活化机理的DFT研究 

      张达 (2015-01-09)
      甲烷C-H键活化是最基础的化学问题之一。金属氧化物是其常用催化剂,而V基催化剂则被认为是甲烷C-H选择活化性能较高的催化剂之一,但有关的活性位、作用机理、影响反应活性的因素等尚有许多不明确之处。 本文采用密度泛函理论(DFT)方法,从简单的V(Ⅴ)-O团簇模型出发,得到了一些结构、电荷对甲烷C-H活化性能的影响规律,以期为轻质烷烃选择氧化催化剂的设计提供一定的参考。计算结果表明: 1.针对V(Ⅴ)-O(-H)中性团簇结构的V=Ot、V- ...
    • “V+adj+了”动补结构分析及在对外汉语教学中的应用 

      徐志刚; 李绍玉 (2006-3-15)
      “V+AdJ+了“是汉语中常用的一种动补结构。在这一结构中,“AdJ“所表达的状态是“V“动作的结果,且“AdJ“所表的状态与“V“动作发生之前相比发生了变化。我们注意的是,这种结构在一定的条件下会产生歧义,进而影响整个句子的表达功能。在对外汉语教学中,对这种结构加以深入分析,有利于学生更好地掌握和运用动补结构。·
    • V-MCM-41 for selective oxidation of propane to propene and acrolein 

      ZHANG, QH; WANG, Y; OHISHI, Y; SHISHIDO, T; TAKEHIRA, K; 王野 (2001)
      The V-MCM-41 with lower V content catalyzes the oxidation of propane to acrolein with a yield of 3.3% and selectivity of 20%, while that with higher V content mainly produces propene.
    • V/P复合氧化物上C–H键活化的密度泛函研究(英文) 

      傅钢; 袁汝明; 汪佩; 万惠霖 (2015-9-20)
      选择氧化催化剂通常为多组分复合氧化物.一般认为,高价过渡金属的端末双键氧(M=O)是烷烃活化的中心,而非金属端氧(nM=O)与烷烃活化无关.但近期的理论研究发现,复合氧化物中非金属端氧也可能参与烷烃活化.本文采用密度泛函方法(b3lyP)对比V=O和P=O的脱氢活性,并深入揭示二者的差异.H脱除反应可以视为是质子偶联电子传递的过程.对于V/P复合氧化物,V5+充当电子的受体,而V=O和P=O均可接受质子.由于P=O具有更强的质子化能力, ...
    • V_2O_5/C电化学电容器有机电解液的性能研究 

      王虹; 唐致远; 李中延; 庄新国; WANG Hong; TANG Zhi-yuan; LI Zhong-yan; ZHUANG Xin-guo (厦门大学《电化学》编辑部, 2008-05-28)
      以偏钒酸铵为反应原料,采用液相沉淀法制备出不定型V2O5电极材料.以V2O5为正极,石墨为负极,分别选用1.0 mol/L LiClO4/EC+DMC、1.0 mol/L LiPF6/EC+DEC+DMC、1.6 mol/L Et4NBF4/AN 3种有机电解液组成不对称电化学电容器,恒流充放电、循环伏安和交流阻抗等测试该模拟电容器,如以1.0 mol/LLiClO4/EC+DMC作电解液则具有良好的循环性能和较小的阻抗,且在500 ...
    • V_2O_5/MPO_4在丙烷氧化脱氢中的催化作用 

      张伟德; 沙开清; 李基涛; 古萍英; 万惠霖 (1999-03-20)
      研制了具有不同酸碱性的磷酸盐MPO4(M=Al,Zr,Ca)载体,并用这些载体负载06%~60%的V2O5。所制备的催化剂在丙烷氧化脱氢反应中具有较好的催化性能,如3%V2O5/Ca3(PO4)2催化剂在丙烷转化率为170%时,丙烯选择性可达559%,丙烯收率达95%。考察了不同反应条件下催化剂的性能,表明在高温高空速条件下,3%V2O5/Ca3(PO4)2催化剂的反应活性较好,而3%V2O5/Zr3(PO4)4催化剂在低温低 ...
    • Vacancy or not: An insight on the intrinsic vacancies in rocksalt-structured GeSbTe alloys from ab initio calculations 

      Zhou, J.; Sun, Z.; Pan, Y.; Song, Z.; Ahuja, R.; 周健 (EPL-EUROPHYS LETT, 2011-07)
      Rocksalt-structured GeSbTe (GST) phase-change materials contain significant amounts of intrinsic vacancies at one sublattice. On the basis of ab initio total energy calculations, we have shown that the so-called intrinsic ...
    • Vaccination of the grouper, Epinephalus awoara, against vibriosis using the ultrasonic technique 

      Zhou, YC; Huang, H; Wang, J; Zhang, B; Su, YQ; 苏永全 (ELSEVIER SCIENCE BV, 2002-01-03)
      A novel ultrasonic technique was used to facilitate the vaccination of fish against Vibrio alginolyticus. To establish the safety parameters, we first tested the effects of ultrasound treatment on juvenile groupers, ...
    • Vacuum Rabi Splitting of Exciton-Polariton Emission in an AlN Film 

      Li, Kongyi; Wang, Weiying; Chen, Zhanghai; Gao, Na; Yang, Weihuang; Li, Wei; Chen, Hangyang; Li, Shuping; Li, Heng; Jin, Peng; Kang, Junyong; 康俊勇 (NATURE PUBLISHING GROUP, 2013-Dec 1)
      The vacuum Rabi splitting of exciton-polariton emission is observed in cathodoluminescence (CL) and photoluminescence spectra of an AlN epitaxial film. Atomic force microscopy and CL measurements show that the film has an ...
    • Valence Band Offsets of LiPON/LiCoO(2) Hetero-Interfaces Determined by X-ray Photoelectron Spectroscopy 

      Song, Jie; Jacke, Susanne(Tech Univ Darmstadt, Dept Mat Sci); Cherkashinin, Gennady(Tech Univ Darmstadt, Dept Mat Sci); Schmid, Stefan(Tech Univ Darmstadt, Dept Mat Sci); Dong, Quanfeng; 董全峰; Hausbrand, Rene(Tech Univ Darmstadt, Dept Mat Sci); Jaegermann, Wolfram(Tech Univ Darmstadt, Dept Mat Sci) (ELECTROCHEMICAL SOC INC, 2011-10-26)
      Interfaces within Li-ion batteries are of interest with respect to stability and transfer resistance. In this paper, we investigated LiPON/LiCoO(2) hetero-interfaces formed at room temperature (RT) and 200 degrees C using ...
    • Valence Band Offsets of LiPON/LiCoO2 Hetero-Interfaces Determined by X-ray Photoelectron Spectroscopy 

      Song, Jie; Jacke, Susanne; Cherkashinin, Gennady; Schmid, Stefan; Dong, Quanfeng; Hausbrand, Rene; Jaegermann, Wolfram; 宋杰; 董全峰 (ELECTROCHEM SOLID ST, 2011)
      Interfaces within Li-ion batteries are of interest with respect to stability and transfer resistance. In this paper, we investigated LiPON/LiCoO2 hetero-interfaces formed at room temperature (RT) and 200 degrees C using ...
    • Valence bond calculations of hydrogen transfer reactions: A general predictive pattern derived from theory 

      Peifeng Su; Lingchun Song; Wei Wu; 吴炜; Philippe C. Hiberty; Sason Shaik (AMER CHEMICAL SOC, 2004-09)
      Hydrogen abstraction reactions of the type X-. + H-H' --> X-H + H'(.) (X = F, Cl, Br, l) are studied by ab initio valence bond methods and the VB state correlation diagram (VBSCD) model. The reaction barriers and VB ...
    • Valence bond calculations on the transition state for the E2 reaction of fluoride ion with ethyl fluoride - Implications for the More O‘Ferrall-Jencks diagram 

      Wu, W; Shaik, S; Saunders, WH (2005-09)
      A valence bond self-consistent field (VBSCF) calculation has been carried out on the bimolecular elimination (E2) reaction of fluoride ion with ethyl fluoride. The transition state was first optimized at HF/6-31+G and the ...
    • Valence bond configuration interaction: A practical ab initio valence bond method that incorporates dynamic correlation 

      Wu, W; 吴玮; Song, LC; Cao, ZX; 曹泽星; Zhang, Q; Shaik, S (AMER CHEMICAL SOC, 2002-02-27)
      A post-VBSCF method, called valence bond configuration interaction (VBCI), is developed here. The method incorporates dynamic correlation, by use of configuration interaction (CI) to improve the energetics after a VBSCF ...
    • Valence bond description for the ground state and several low-lying excited states of LiH 

      Yirong Mo; 莫亦荣; Wei Wu; 吴玮; Qianer Zhang; 张乾二 (Elsevier Science Publishers, 1992-07)
      The potential energy curves of the ground and four singlet low-lying excited states of LiH were calibrated using the bonded tableau unitary group approach (BTUGA). The results show that the ground and the first excited ...
    • Valence bond Modeling of barriers in the nonidentity hydrogen abstraction reactions, X 'center dot+H-X -> X '-H+X center dot (X ' not equal X = CH3, SiH3, GeH3, SnH3, PbH3) 

      Song, LC; Wu, W; 吴玮; Dong, KM; Hiberty, PC; Shaik, S (AMER CHEMICAL SOC, 2002-10-24)
      Breathing orbital valence bond (BOVB) computations (Hiberty, P. C.; Humbel, S.; Byrman, C. P.; van Lenthe, J. H. J. Chem. Phys. 1994, 101, 5969) are used to obtain nonidentity barriers for hydrogen transfer reactions between ...
    • Valence Bond Perturbation Theory. A Valence Bond Method That Incorporates Perturbation Theory 

      Chen, Zhenhua; Song, Jinshuai; Shaik, Sason(Hebrew Univ Jerusalem, Inst Chem); Hiberty, Philippe C.(Univ Paris 11, CNRS); Wu, Wei; 吴玮 (AMER CHEMICAL SOC, 2009-07)
      A post-VBSCF method, called valence bond second-order perturbation theory (VBPT2), is developed in this paper and is shown to be (i) economical and (ii) at par with more sophisticated VB and MO-based methods. The VBPT2 ...
    • Valence bond study of dissociation behavior and spectroscopic constants for the ground states of LiF and NaF 

      Cao, ZX; 曹泽星; Wu, W; 吴玮; Zhang, QE; 张乾二 (HIGHER EDUCATION PRESS, 1998)
      Ab initio VB calculations were used to determine the accurate spectroscopic parameters of the ground stated of LiF and NaF. A set of potential energy curves corresponding to the ground states including ionic and covalent ...