过渡态

The factors A and the rate constants are given at temperature range of 200-1200 K.The results in-dicate that the loss of aβ-hydrogen from 2-hydroxyethyl radical to yield vinyl alcohol and that a 1,3-hydrogen shift to form ethoxy radical have close A factors and rate constants.

用量子化学结果和Eyring过渡态理论计算了200－1200K温度范围内，标题反应的A因子和速度常数，结果表明，2－羟乙基脱去β－H生成乙烯醇与其经［1，3］重排生成乙氧基有相近的A因子和速度常数，且常温下速度较慢，反应难以进行。

This means that, in principle, there is a well-defined transition state on the lower surface.

这就意味着，理论上，低势能面上有一个定义良好的过渡态。

Quantum chemical and molecular mechanical methods were employed to study the acylation in the acetylthiocholine hydrolysis catalyzed by acetylcholinesterase.

应用量子化学和分子力学方法研究乙酰胆碱酯酶催化硫代乙酰胆碱水解反应中的乙酰化反应，计算了反应物、过渡态、产物及中间体的几何结构及电子结构。

The results show that formation of an enzyme-substrate complex is "anticatalytic".

结果表明：稳定过渡态结构有利于酶促反应，酶-底物在反应物时相互作用仅仅是降低酶的催化效率。

One of the major problems,however,remains the poor solubility and membrane permeation of pepstatin, as well as its lack of selectivity among aspartyl proteases.The amino acid statine can mimic the tetrahedral transition-state of amide bond hydrolysis but cannot itself be hydrolyzed by the enzyme.

分子中含有两个非天然氨基酸statine能模拟天冬氨酸蛋白酶底物活性部位的四面体水解过渡态，且本身不易被切割，通过氢键和酶的天冬氨酸残基结合。

The results show that there are eight reaction channels, corresponding to eight transition states, in the reaction process. The main parts of all transition states are non-planar five-membered ring, in which the geometry of Z -benzaldoxime and E -benzaldoxime is maintained partially, but the bond length, bond angle and charge are all changed.

结果表明，在苯甲醛肟与炔丙醇加成反应过程中， 8个可能反应通道的过渡态中均形成非平面五元环结构，其中苯甲醛肟的 Z 、 E 构型特征得到了部分保留，但主要部分的键长、键角均发生了变化，电荷也进行了重新分布。

The mechanism of carbon-nitrogen coupling reaction of 2-Iodo-selenophene with benzamide catalyzed by CuI has been investigated with density functional theory at GGA/PW91/DND level. The geometric configurations of reactants, intermediates, transition states, and products were optimized and verified by means of vibration frequency calculations.

采用密度泛函理论方法，在GGA/PW91/DND基组与水平上研究了2-碘代硒苯与苯甲酰胺在CuI催化下的微观反应机理，优化了反应过程中的反应物、中间体、过渡态和产物。

A rearrangement model for the complex and its isomers of the2+ was proposed, in which there could be two competed steric courses with the trigonal bipyramidal intermediate or intermediates.

利用[Co(3，3-tri)Cl]2+体系配合物及其异构体结构模型提出了一个2+型的配合物及其几何异构体相互转换所遵循的重排机理模型。认为在该类型配合物异构体转化过程中同时存在两个竞争途径，其中间过渡态或中间体分别为三角双锥或四角锥形式。

Base-catalysed hydrolysis is a typical course involving deprotonation leaving of Cl- and formation of the trigonal bipyramidal intermediate; edge displacement and ligand folding courses involve leaving of Cl- and formation of the square pyramidal intermediates.

典型的途径有经式异构体的碱催化水解，过程通过脱氢、脱氯以及三角双锥中间过渡态或中间体的形成来完成；另一途径为边沿取代及配体翻转历程，过程通过脱氯及四角锥的形成来完成。

The results show that the formation of dry gas is abided by reaction mechanism involving the cleavage of pentacoordinated Carbonium ion which is formed by the protonation of alkanes over acidic catalyst.

结果表明，烷烃分子首先在催化剂酸性中心作用下发生质子化反应，烷烃分子链上易受到氢质子进攻的位置一般在其叔碳原子或碳链中心碳原子附近的C—H键或C—C键处，形成两种反应过渡态物种——五配位正碳离子H-Carbonium和C-Carbonium。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失