顺式

B3LYP/6-311++G** calculations were carried out to study the trimethylamine catalyzed Baylis-Hillman reaction between acraldehyde and formaldehyde.

采用密度泛函DFT-B3LYP方法在6-311++G**基组下计算研究了三甲胺催化的丙烯醛和甲醛的Baylis-Hillman反应的微观过程，获得了两种反应通道(分别对应于顺式-丙烯醛和反式-丙烯醛)的势能面。

The optimized structures and energies of the reactants, intermediates, transition states and products of two reaction channels (corresponding to syn-acraldehyde and anti-acraldehyde) in gas or in methanol solvent were obtained. The potential energy profiles reveal the processes of the trimethylamine-catalyzed Baylis-Hillman reaction between acraldehyde and formaldehyde in gas or in methanol solvent at the microscope level.

通过研究，获得了三种情况下两种反应通道(分别对应于顺式-和反式-丙烯醛)中涉及的反应物、产物、中间体、过渡态的优化结构及其能量，并由此得到了反应的势能面图，在电子微观层次上揭示了三甲胺催化的丙烯醛和甲醛的Baylis-Hillman反应的微观过程。

Configurational isomerism is then due to the presence in the molecule of one or more dissymmetric centres ,in the simplest case asymmetric carbon atoms ,each of which can have and absolute configuration; and ,or ,to the presence of double blonds which can give cis- and trans-geometrical isomers .

构型异构是由于分子中存在一个或一个以上的不对称中心，在最简单的情况下是不对称碳原子，每个不对称碳原子的绝对构型是和；或者，如果存在双键的话，那么将给出顺式和反式几何异构体。

The main compounds in the natural terpineol oil were eucalyptol, trans4thujanol, pisopropenyl toluene, cis4thujanol, linalool, camphor, borneol, 4terpineol,αterpineol and safrole.

天然松油醇粗油中主要成分是1，8桉叶素、反式4艹守醇、p异丙烯基甲苯、顺式4艹守醇、芳樟醇、樟脑、龙脑、4松油醇、α松油醇和黄樟素。

SCE. The peak height is directly proportional to the concentration of maleic acid over a range of 0.07～50μg/ml.

允许共存顺式与反式丁烯二酸的浓度比为1∶250.20次测量的相对标准偏差为1.1％。

From our results, the first structure model of monomeric monocot lectin was established. In addition, the accurate molecular size and amino acid sequence were determined by crystallographic method.

与雪花莲凝集素GNA亚基结构的比较，发现二者C端98～112位氨基酸的肽链走向完全不同，其主要原因是98位与99位残基间的肽键构型不同，GNA为顺式肽键，而GAFP为反式肽键。

The experiment results demonstrate that this solid photosensitizer is efficient for the photoisomerization and easy for separated from the reaction mixtures.

实验结果表明，此固相光敏剂能够有效地敏化反式维生素D3为顺式维生素D3的反应，并且非常容易从反应体系中分离出来。

The results show that the complexes 4a, 5a, 6a from reactions of pyrazine, 4,4\'-bipyridine, bpe and Cp~*Co[S_2C_2B_(10H_(10)] have similar transform structure.

反应表明，由同一类型的二齿配体pyrazine，4，4\'-bipyridine，bpe所得到的化合物4a，5a，6a是具有类似反式结构的化合物，而用bpo作配体得到的化合物7a是一个顺式结构的化合物。

Work was also carried out. From numerous facts of ourprevious work, it might be seen that the stereoselectivity of aziridination viasulfonium ylides depends upon the sulfonium salts and C=X compounds. The moreactive the sulfonium ylide and C=X compound are, the more cis product is generated.Whereas, trans product will be major if the activity of the sulfonium ylide and C=Xcompound is low.

通过对以往工作的总结，我们发现，在经由硫叶立德途径的小环化反应中有一个经验规律：产物的立体选择性与所用的锍盐和C=X化合物有关，即锍盐和C=X化合物的活性增强，有利于形成顺式产物，反之，锍盐和C=X化合物的活性降低，有利于反式产物的形成。

Effects of microwave power, reaction time, reaction temperature, solvent etc. on reaction were studied by a single factor tests. The results show that maleic acid is more active than fumaric acid; the introduction of methyl group on the double bond can weak the reactivity of the Michael addition reaction; the ester base is more propitious to complete the Michael addition reaction than the nitrile base.

为研究微波下迈克尔反应的规律，本文采用单模聚焦微波有机合成仪，通过对顺丁烯二酸、反丁烯二酸和氨水合成DL-天冬氨酸、顺式3-甲基丁烯二酸和氨水合成3-甲基天冬氨酸、丙烯酸甲酯和氨水合成β-丙氨酸、丙烯腈和氨水合成β-氨基丙腈等五个反应对迈克尔加成反应进行了研究。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。