查询词典 alkenes

The research developments in synthesis and application of silicotungstate with Keggin-type structure and its derivants used as catalysts in epoxidations of alkenes were reviewed.

综述了近十年来新型 Keggin结构硅钨酸盐及其一系列衍生物催化剂的合成及其在选择氧化反应中应用的研究进展。

The chiralMn complexes, especially Jacobsenscatalyst, display high enantioselectivity for asymmetric epoxidation of conjugated cis-di-, tri-and some tetrasubstituted prochiral alkenes in the NaClO biphasic system, but the epoxidationreaction generally requires a long reaction time even in the presence of an axial ligand.

在NaClO两相体系中，手性Mn配合物，尤其是Jacobsen催化剂，对共轭顺式二取代、三取代和部分四取代烯烃的不对称环氧化具有高的对映选择性，然而即使存在轴向配体，环氧化反应也通常需要长的反应时间。

The chiralMn complexes, especially Jacobsen\'scatalyst, display high enantioselectivity for asymmetric epoxidation of conjugated cis-di-, tri-and some tetrasubstituted prochiral alkenes in the NaClO biphasic system, but the epoxidationreaction generally requires a long reaction time even in the presence of an axial ligand.

在NaClO两相体系中，手性Mn配合物，尤其是Jacobsen催化剂，对共轭顺式二取代、三取代和部分四取代烯烃的不对称环氧化具有高的对映选择性，然而即使存在轴向配体，环氧化反应也通常需要长的反应时间。

In this paper, an approach to two problems in organic chemical teaching was made:(1) Determination of the type and the number of Cis-trans isomers of acyclic alkenes;(2)An easy way to convert a Fischer Projection into a zigzag representation.

对如下两个有机化学教学问题进行了探讨：(1)如何确定链状多烯顺反异构体的数目和类型；(2)单糖的Fischer投影式转变为透视式的简便方法。

Understand the chemistry of alkenes and alkynes: nomenclature, electronic structures, sequence rule, cis-trans isomers, electrophilic addition reactions and mechanism, Markonikov's rule, conjugated dienes, rules of resonance forms.

A2 E3 了解烯类及炔类的化学性质：命名、电子结构，顺反异构物，亲电子加成反应及机制，马克尼可夫规则，共轭双键及共振式。

Alkanes, alkenes, and alkynes are all hydrocarbons (compounds made up of hydrogen and carbon only).

链烷、链烯和链炔都是碳氢化合物（纯净的碳和氢所组成的化合物）。

Table 2 shows names for some alkyl groups, alkanes, alkenes and alkynes.

表2显示了一些烷基、烷烃、烯烃及炔烃的命名。

So it is very necessary to study the characters and extend applications of this kind of alkenes with electron-donating substituents.

因此，深入研究具有供电子基团的活化烯烃的各种性质，扩展它们在各个领域的应用具有十分重要的意义。

Epoxidation of alkenes is one of the most important reactions in organic, synthesis.

烯烃环氧化在有机合成中占有十分重要的地位。

Light alkenes play a significant role in the petrochemical industry.

低碳烯烃在石化工业中起着举足轻重的作用。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。