互变异构化

The tautomerism of neutral cytosine in gas phase was investigated byB3LYP/6-311+G** method.

利用密度泛函理论的B3LYP/6-311+G~方法，研究了胞嘧啶分子的互变异构化现象。

The ground-state structures of 8 tautomers of cytosine were fully optimized at B3LYP/6-311+G(superscript **) level, and the tautomerism of 6 relatively stable tautomers of cytosine was studied.

用该方法对胞嘧啶分子的8种异构体构型进行了充分优化，研究了其中能量较低的6种胞嘧啶异构体的互变异构化过程。

Master the Keto-Enol tautomerism; reactions of enols:α-H substitution reactions;α-halogenation of aldehydes and ketones;α-bromination of carboxylic acids; acidity ofα-H atoms: enolate ion formation; reactivity of enolate ions; alkylation of enolate ions; mechanism of carbonyl condensation reactions;condensations of aldehydes and ketones: the Aldol reaction; dehydration of Aldol products; the Claisen condensation reaction; the Michael addition.

熟练掌握酮式－烯醇式互变异构；烯醇的反应：α-H的活性；醛酮的α卤代反应；羧酸的α-溴代反应；α-H的酸性：烯醇负离子的形成；烯醇负离子的反应；烯醇负离子的烃基化；羰基化合物的缩合反应机理；醛酮的缩合反应－Aldol缩合；Aldol缩合产物的脱水反应； Cleisen 酯缩合反应；麦克尔加成反应。

Hydration of Alkynes, Tautomerization.

炔烃的水化作用，互变异构化。

Starting with two reactive methylene compounds, ethyl cyanoacetate and malononitrile, two 5-amino-1H-pyrazoles were prepared through the intermediates ketene dithioacetal.

从两个活泼亚甲基化合物开始，经过乙烯酮二硫代缩醛中间体，合成了两个5-氨基-1H-吡唑，以这个两个化合物为中间体，与芳香族和脂肪族α-溴代酮反应，而后经酸催化亚胺化互变异构后得到含咪唑并[1，2-b]吡唑甲硫醚类化合物6a-6g。

The results are in good agreement with available experimental results. The entropy effect on the Gibbs free energies of 6-thioxanthine base is very small and there is little significance for the tautomeric equilibria of the base.

计算结果同已有实验结果一致。6-硫代黄嘌呤异构化的熵效应小，对互变异构平衡几乎没有显著的影响，而焓变对互变异构产生了主要的影响。

The mechanism of clonidine conformational isomerization and tautomeric reaction has been studied and the geometric parameters of transition states have been located by B3LYP/6-31G**.

为了考察氯苯的共轭效应对可乐定互变异构体稳定性的影响，在B3LYP/6-31G**水平上，研究了2-氨基-2-咪唑啉的互变异构化反应机理。

In the first part, the prototropic hydroxy-oxo tautomerisms of 2 (1H)- pyridones/2-hydorxypyridines, one of the most important model systems in molecular biology, have been investigated with self-consistent reaction field method based on continuum model. The influence of the nature and position of substituent groups, the existence of intramolecular hydrogen bonding and tautomeric competition between 2-hydroxy and 4-hydroxy on the tautomeric equilibria have also been examined.

第一部分，首先从溶剂敏感的异构化性质入手，用基于连续介质的自洽反应场理论方法对一类重要的生化模型体系—2（1H）-吡啶酮／2-羟基吡啶互变异构体系进行了研究，系统地考察了取代基性质、取代基位置、分子内氢键的形成以及互变异构竞争的存在对异构化平衡的影响。

And we also research the impact of methylating on hydrogen bond and stacked bond in base pairs under considering water molecules.

研究结果表明，烷基化之所以能造成碱基错配是它可使碱基的质子迁移或烯醇互变现象容易发生，改变原有原子的电荷分布或配对模式，同时碱基自身的互变异构体会跟烷基作用，致使互变异构体能够稳定存在，影响正常碱基配对，引起碱基诱变，造成生理疾病的发生。

She gently rebuff ed him, but agreed that they could be friends

她婉言拒绝了，但同意作为朋友相处。

If in the penal farm, you were sure to be criticized.

要是在劳改农场，你等着挨绳子吧！