电子异构体

The excited-state intramolecular proton transfer tautomerism reaction of 6-methyl-4-hydroxy pyri-midine monomers and dimmers was investigated by the ab initio method with the self-consistent reaction field with Tomas's polarized continuum mode and CIS theories at HF level on the basis of 6-311+G* and 6-31G basis set. By studying the potential energy surface, it was found that the monomer's ground-state proton transfer process together with the excited-state proton transfer process is a molecular system of four energy level, but dimmers were not, which can be used to explain the fact that UV-visible absorption and fluorescence spectra of monomer and dimers all corresponded to quinoid.

采用 ab initio HF理论的组态相关CIS方法和连续溶剂模型PCM，分别在6-311+G*和6-31G水平上研究了6-甲基-4-羟基嘧啶单体及二聚体激发态质子转移的异构化反应；对其反应势能面的研究发现，单体基态和激发态的异构化反应一起可以形成四能级的分子电子体系，而二聚体的却不能，由此解释了单体和二聚体的紫外吸收光谱和荧光发射光谱均对应于酮式构型的原因。

The electron impact mass spectra of noncyclic crown ether s with heterocyclic methmazole as terminal groups 1a￣4a and fo were given and discussed in the present article.

本文给出以杂环甲巯咪唑为端基的非环冠醚1a～4a及1a的异构体1b的电子轰击质谱并讨论之。

Cis-C=C configuration on 2 position is easily isomerized to trans-form in environment according to literatures, but cycloproyl do it difficut relatively. So, replacement of 2,3- allyl unit by cyclopropyl group might give a practical method to get over the problem.

为解决脱落酸2位双键在环境中易光异构化为反式结构的问题，依据电子等排体原理，将2，3-位的烯丙型的结构改变为环丙型结构，将可能解决光异构化的问题。

The free energy of solvation is well correlated with the dipole moments of 5-fluorouracil and 5-chlorouracil tautomers.

另外， 详细地将5-氟尿嘧啶和5-氯尿嘧啶与尿嘧啶进行了对比，获得三者最稳定异构体间电子结构异同的有用信息。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。