排序方式: 共有57条查询结果,搜索用时 218 毫秒
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硝基甲烷热解机理的量子化学研究 总被引:3,自引:0,他引:3
用ab initio和NMDO 两种方法, 对CH~3NO~2沿C-N键断裂的热解反应过程 进行了较细致的计算研究。所得势能曲线(E-Rc-n) 彼此一致,并与Kaufman等[1]的近期结果相符。将各单点下所得正则离域化处理, 发现当C和N原子间的距离Rc-n=1.6-1.8A时, 定域成键σc-n-MO从能级较低的五的个占有MO跃升为HOMO(即第16个MO)。考察占有末占有前沿轨道 能级和位相, 可推在CH~3NO~2热 解的初抬阶段, 通过分子重排成C-O键的可能性较小 。其热解引发步骤可能是生成.CH~3和.NO~2双自由基。 相似文献
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分光光度法同时测定无机多组分体系的研究III: 微量钨, 钼, 钛的测定 总被引:4,自引:0,他引:4
本文从配合物吸收光谱行为及矩阵运算角度分别探讨了CPA矩阵法AKC矩阵法中波长选择对分析结果误差的影响. 在前人有关钨, 钼, 钛单个元素光度测定研究的基础上, 确定了适宜于钨, 钼, 钛一苯基荧光酮-溴代十六烷基三甲铵三元配合物同时光度测定的最佳条件, 拟定了不经分离直接光度测定钨, 钼, 钛的方法. 相似文献
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《Composite Interfaces》2013,20(8-9):693-706
It is known that SiC/SiC composite has high strength and toughness, but is degraded when exposed in air at high temperatures due to the propagation of the crack made by the premature fracture of the SiO2 layer. It is also known that the fracture morphology of this composite varies from fiber pull-out type to non pull-out type with progressing oxidation. The present work aimed to describe such a behavior with a computer-aided Monte Carlo shear lag simulation method. The experimentally measured variation of strength of the unidirectional composite as a function of thickness of the SiO2 layer and also as a function of exposure time and temperature, and the experimentally observed variation of fracture morphology with progressing oxidation, could be reproduced satisfactorily by this method. 相似文献
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In this paper we establish a result about uniformly equivalent norms and the convergence of best approximant pairs on the unitary ball for a family of weighted Luxemburg norms with normalized weight functions depending on ε, when ε→ 0. It is introduced a general concept of Pade approximant and we study its relation with the best local quasi-rational approximant. We characterize the limit of the error for polynomial approximation. We also obtain a new condition over a weight function in order to obtain inequalities in Lp norm, which play an important role in problems of weighted best local Lp approximation in several variables. 相似文献
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H. Mohebi A. M. Rubinov 《分析论及其应用》2006,22(1):20-40
We develop a theory of downward sets for a class of normed ordered spaces. We study best approximation in a normed ordered space X by elements of downward sets, and give necessary and sufficient conditions for any element of best approximation by a closed downward subset of X. We also characterize strictly downward subsets of X, and prove that a downward subset of X is strictly downward if and only if each its boundary point is Chebyshev. The results obtained are used for examination of some Chebyshev pairs (W,x), where ∈ X and W is a closed downward subset of X 相似文献
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Songping Zhou Dansheng Yu Ruijun Le 《分析论及其应用》2007,23(1):92-100
We investigate some conditions in Fourier analysis as a generalization of monotonicity condition. Especially, we give some applications of GBVS and sequences satisfy the condition ΔB1 and ΔB2. 相似文献
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