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991.
992.
M. A. Mora Laura Galicia M. A. Mora‐Ramirez 《International journal of quantum chemistry》2004,97(6):983-991
The molecular and electronic structures of 5‐amino‐1,10‐phenanthroline and its monoprotonated and diprotonated species were obtained from ab initio quantum mechanical calculations with unrestricted Hartree–Fock (HF) and Møller–Plesset perturbation theories. The analysis of the net atomic charges and the total spin densities show three possible sites for the monomeric coupling in the polymerization process. The minimal energy conformation for the different kinds of coupling in the formation of the dimers was obtained. The studies were extended to the HF/6‐311 + G(2d,p)//B3LYP (Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar)/6‐31G(d) level of theory to obtain theoretical nuclear magnetic resonance spectra to study the number and kinds of species involved in the protonation mechanism. Theoretical and experimental nuclear magnetic resonance spectra are in excellent agreement. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
993.
994.
An edge of a k-connected graph is said to be k-contractible if the contraction of the edge results in a k-connected graph. A k-connected graph with no k-contractible edge is said to be contraction critically k-connected. We prove that a contraction critically 5-connected graph on n vertices has at least n/5 vertices of degree 5. We also show that, for a graph G and an integer k greater than 4, there exists a contraction critically k-connected graph which has G as its induced subgraph. 相似文献
995.
用“团簇埋入自洽计算法”对LaNi5晶体表面进行了全电子、全势场、自旋极化的从头计算. 在原子纵向坐标充分弛豫的条件下,得到处于最低基态总能量下LaNi5晶体的非平整表面空间结构及其电子结构. LaNi5晶体最表面La原子向外凸出,Ni原子向里收缩,凹凸不平的表面层增加了表面原子与氢原子的接触面积;而表面层的有效体积增大了约9%,有利于氢原子的进入. LaNi5晶体表面态的费米能量大大高于体材料的费米能量. 在费密面上主要是Ni的3d电子,价带未填满,显示金属性. LaNi5晶体表面第一、第二层有1.15个电子从La原子向Ni原子转移,这两层有反向的微小自旋磁矩,从而使表面显示顺磁性. 得到了LaNi5晶体表面的价带电子态密度. 用过渡态方法计算了LaNi5晶体表面的电离能和电子亲和势. 所有计算结果显示:LaNi5晶体表面的性质与体性质显著不同,而与氢化物LaNi5H7的性质非常相近. 这说明LaNi5晶体的表面结构有利于氢原子的吸收.
关键词:
5')" href="#">LaNi5
表面
电子结构
团簇埋入自洽计算法 相似文献
996.
H. Q. Lu J. D. Zhu Z. G. Huang L. M. Shen 《International Journal of Theoretical Physics》2006,45(1):1-5
Application of the 5-dimensional coordinate transformations in the 5-dimensional theory lead us to some new solutions for the 4-dimensional Einstein–Maxwell equations and the relevant scaler equation. From the Kerr solution we derive the corresponding solution. And we propose a new method to solve the usual 4-dimensional Einstein–Maxwell equations and the scalar equation, illustrating by three examples. 相似文献
997.
为了制作能满足YBCO涂层导体(coated conductor)所需要的高强度、低磁性的立方织构基带,本工作用粉末冶金方法制作了Ni-5at%W合金基带.为评估基带中立方织构的发展,用March-Dollase函数对各种热处理样品的择优取向度进行了研究,结果与用X射线极图法和电子背散射衍射法得到的结果基本一致.研究结果表明,在实验中所用的工艺参数范围内,随总加工率和热处理温度的提高,基带中立方织构百分数明显增高.提高总加工率实际增加了冷加工样品中立方织构晶粒或立方核心的数量.实验中得到了较好的和实用的工艺制度,用这种工艺可以制作出具有99%~100%立方织构百分数,并具有很好一致取向度的Ni5W基带. 相似文献
998.
Bekir Dizman Lon J. Mathias 《Journal of polymer science. Part A, Polymer chemistry》2005,43(23):5844-5854
Ethyl α‐chloromethylacrylate was converted to an ester derivative using 5‐chlorovaleric acid in a single step. The homopolymerization of the new monomer (CEMA) and its copolymerization with methyl methacrylate were performed using photoinitiator Irgacure 651. The polymers were reacted with N,N‐dimethyldodecylamine to obtain polymers with pendant quaternary ammonium (QA) moieties. The polymers with pendant QA groups were used in self‐catalyzed phase transfer reactions with sodium phenoxide and 1‐dodecanethiol. The syntheses of the monomer and polymers were followed by FTIR, 1H NMR, and 13C NMR. The average polymer molecular weights and polydispersities were determined by size exclusion chromatography. Thermal analysis was carried out using thermogravimetric analysis and differential scanning calorimetry. The copolymer composition, degree of quaternization, and degree of conversion in phase transfer reaction were determined by 1H NMR. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5844–5854, 2005 相似文献
999.
非晶态HoP5O14的蓝绿波段上转换发光的分析 总被引:2,自引:0,他引:2
本文报道了脉冲DCM染料激光导致的非晶态HoP5O14的兰绿波段的上转换发光现象,从实验和理论上对其上转换发光的现象,机理和能道行了测量,分析和计算;结果表明对^5F3和S2能级,其上转换发光主要由离间能量传递机理导致;对5G4和(5G3G)5能级,则步进双光子吸收和离子间能量传递共同参与导致了它们的上转换发光。 相似文献
1000.
Caiqi Wang Yuping Dong Huimin Tan 《Journal of polymer science. Part A, Polymer chemistry》2003,41(2):273-280
After the protection of partial hydroxyl groups with trimethylsilyl (TMS) groups, hydroxypropyl cellulose becomes soluble in organic solvents, and the number of hydroxyl groups as initiating groups can be controlled. As a result, a new brushlike graft poly(?‐caprolactone) can be prepared with hydroxypropyl cellulose as the backbone polymer by homogeneous ring‐opening graft polymerization and deprotection. The protection and deprotection of the TMS group during the entire procedure were carefully monitored with Fourier transform infrared (FTIR) and NMR, and the final graft copolymers were characterized with FTIR, 1H NMR, 13C NMR, gel permeation chromatography, and differential scanning calorimetry. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 273–280, 2003 相似文献