烯丙式卤代烃在亲核取代反应中的活性

在亲核取代反应中;无论按SN1历程还是SN2历程,烯丙式卤代烃的反应速度都是最快的.一般教材对按SN1历程进行的反应机制介绍较多,而对SN2历程的反应机制则未说明原因.本文拟对烯丙式卤代烃按SN2历程反应的特点进行较深入的分析.     

羽毛球运动员动作前情境的预判绩效及其差异性研究

选取16名羽毛球专业运动员和8名大学生初学者为被试,以羽毛球专项情境中对手即将回球的动作前情境为反应任务,来探讨运动员的预判绩效及其差异性问题.结果显示:(1)在动作前情境中,运动员存在明显的预判现象,预判能力随水平的提高而提高;(2)不同水平运动员的预判绩效差异主要表现在准确性上,反应速度差异不显著;(3)运动员的预判自信心和选择反应时对专项情境预判绩效没有显著性影响.     

联二萘酚双钠盐催化的Henry反应研究

Henry反应是重要的形成碳碳键的反应之一,在有机合成中有着广泛应用.通常的henry反应催化剂为强酸或者强碱,能否找到一种温和的催化剂来催化此反应呢?通过筛选,我们发现在催化剂量的联二萘酚双钠盐(3 mol %)存在下,henry反应能够快速的进行,产率高达100%.此催化剂催化的henry反应不但反应迅速而且条件温和.     

配合物取代反应SN2机理的轨道理论研究

根据分子轨道理论，研究了配合物取代反应SN2机理的过渡态结构与能量，提出了SN2机理的过渡态轨道理论。     

固载杂多酸的合成、表征及催化异丙醇脱水反应的活性

采用浸渍法制备负载型HPA／MCM－41催化剂，用FT－IR，XRD表征了催化剂的骨架和晶体结构及性能。负载后HPA的酸强度得到了提高，其Keggin结构仍然保持。适量的杂多酸对MCM－41的介孔性质无影响。不同载体与HPA之间的作用不相同。固载化HPA应用于异丙醇气相脱水反应，得到了与表征完全一致的结果。     

Coupling reaction mechanism of 2-(2-bromo-4-fluoro-phenyl)-1-cyclohexen-1-yl trifluoromethane-sulfonate

The detailed mechanism of CuI-catalyzed C-O intramolecular coupling reaction of 2-（2-bromo-4-fluoro-phenyl）-l- cyclohexen-1-yl trifluoromethane-sulfonate was studied with the density functional theory （DFT）. The geometries of the reactants, transition states, intermediates and products were optimized at the B3LYP/6-31 ＋G＊ level. Meanwhile, the single point energy of species involved in gas and solvent at B3LYP/6-31 I＋G＊ level was individually investigated. Polarizable continuum models （PCM） were applied to the dioxane and water solutions at the same level, respectively. Results show that the rate-limiting step, M3→TS3, does not change in different solutions. However, the activation energy in a dioxane solution is lower than that in water, which explains the previous experimental results. Compared with the non-catalyzed reaction process, the activation energy of the rate- limiting step is reduced by 56.53 kJ mo1-1 in gas and 44.84 kJ mol-l in solvent, demonstrating a high catalytic efficiency of CuI.     

Study on the thermal decomposition kinetics of nano-sized calcium carbonate

INTRODUCTIONTherearefewofquantitativethermalanalysis(TA)investigations (Mulokozi,1992 )ofthegoverningrelationsbetweentheparametersofsolidphasereactionkineticsandtheaveragedi ametersofultrafinecalciumcarbonateandtheeffectsoffineparticlesontheirsolidphasere…     

论配偶权

在<婚姻法>的修订过程中,"配偶权"这样一个概念引起了社会广泛讨论.本文从"配偶权"的来源、法理逻辑及其尴尬,爱情与婚姻的历史发展等方面进行分析,认为"配偶权"的强调是对历史的反动,将对社会中正在发育的婚姻从以财产为基础向以情感为基础转化的现象产生逆诱导,从而增加社会的不稳定因素.     

Public reaction to information release for crisis discourse by organization: Integration of online comments

This study explores how online comments influence public reactions to organizational crisis discourses based on five scenarios depicting typical online comment patterns. Through an empirical study involving 621 participants, several key findings are obtained. First, online comments have a significant effect on post-crisis reactions involving emotions, attitudes and behavioral intentions. However, except in the case of perceived comment manipulation, public reaction patterns associated with overwhelmingly positive and non-overwhelmingly positive comments are not significantly different and are friendlier to the crisis organization than the other three patterns. Moreover, reactions associated with the pattern in which there are no online comments are quite similar to those associated with the pattern of non-overwhelmingly negative comments. Second, positive emotions enhance perceived organizational integrity, whereas negative emotions reduce this perception. Third, perceived comment manipulation has a negative moderating effect on the relationship between positive emotion and perceived organizational integrity and a positive moderating effect on the relationship between negative emotion and perceived organizational integrity. Finally, emotions and perceived organizational integrity are found to be predictors of loyalty and boycott intentions. The findings of the study extend the present knowledge on crisis communication by highlighting the impact of online comments on the post-crisis reactions of the public and also provide crisis managers with guidelines on how to deploy appropriate crisis communication strategies.     

激励介质的非线性波型动力学

以刻划著名的Belousov Zhabotinsky化学反应的俄勒冈振子为数学模型 ,研究解决了激励介质中一些悬而未决的理论问题 (如波的存在性和稳定性等 ) ,进一步完善了激励介质的非线性波型动力学的理论体系 .通过Painlev啨分析 ,B¨acklund变换和奇异摄动方法 ,分析地给出了一些常见的波型解 (如行波 ,螺旋波 ,靶型波 ,V 型波 ,涡卷波等 ) .在波前的邻域内 ,通过引进新的运动坐标系 ,获得了波在直角坐标下的运动方程 .特别是定量地给出了刻划小幅波的组织中心沿轴向和径向运动的规律 ,并由此可判定波的组织中心何时沿径向呈现膨胀或收缩 ,何时沿轴向有正向或反向漂移 .这一结果很好地与实验和数值模拟结果相吻合 .此外 ,研究了耦合的俄勒冈振子 ,解决了Tyson于 1 979年提出的一个猜想 (即对耦合的俄勒冈振子 ,稳定的回声波可以和稳定的正定态共存 ) ,提出了一套解决类似问题的一般方法 .