烯

No squalene synthase polypeptide of expected molecular mass was observed in E. coli containing the putative full-length squalene synthase cDNA, however, overexpression in E. coli was achieved by truncating 30 hydrophobic amino acids at the carboxy terminus.

但在含有全长的鲨烯合酶cDNA的大肠杆菌中并没有观察到预期大小的鲨烯合酶表达，而C末端截短30个疏水氨基酸的鲨烯合酶可在大肠杆菌中过量表达。

Two special structural features of the sulfonium salt were proved to stabilize its corresponding ylide and depress the 2,3-sigma rearrangement. One is that there is a trimethylsilyl in the end of the allylic double band. This silicon atom can stabilize a α-carbon anion and the corresponding ylide. Another is that there is hydroxy group in the beta-position of sulfonium atom. The oxygen of this hydroxy group may stabilize the sulfonium cation.

为了稳定生成的烯丙基硫叶立德，并抑制它的2， 3-sigma 重排反应，在硫叶立德结构上做了两方面的考虑：一是在烯丙基双键的未端引入硅基，利用硅原子对 a -碳负离子的稳定作用来稳定烯丙基硫叶立德；二是在硫原子的 b -位引入羟基，利用羟基氧对硫正离子的作用来稳定硫叶立德。

The structure of all kinds of [60]fullerene derivatives and their characterization via (13)~C NMR spectros-copy are reviewed and the (13)~C NMR spectroscopic properties of various symmetry [60]fullerene derivatives are mainly dis-cussed .

本文全面综述了多种[60]富勒烯衍生物的结构，阐述了(13)~C NMR谱在[60]富勒烯衍生物结构表征中的应用，重点讨论了不同对称性[60]富勒烯衍生物的(13)~C NMR谱图特征。

Chiral homoallylic alcohol was prepared in this paper from asymmetric allylation of aldehyde with enantiomerically pure allylboronate tartramides such as chiral N,N'-diphenyl tartramide and N,N'-di...

本文以手性烯硼酸丙基酒石酸酰胺酯(如烯丙基硼酸-N，N'-二苯基酒石酸酰胺酯)为辅基，进行醛的不对称烯丙基化反应研究。

After ultra high pressure treatment, limonene concentration was decreased greatly while myrcene and α-pinene concentrations were not changed significantly and the concentration of limonene was decreased by 75% after high pressure treatment of 500 MPa for 15 min,α-terpineol and carvone concentrations were increased significantly. The aldehydes concentrations were retained well. The ester concentrations were changed under high pressure treatment, but generally their concentrations were not changed remarkably.

通过定量检测分析发现：超高压处理对橙汁中的柠檬烯成分影响很显著，经500 MPa的压力处理15 min后其含量下降了75%，而月桂烯和α-蒎烯受高压影响较小；α-松油醇、香芹酮含量经高压处理后迅速增加；醛类特征香气成分基本不受高压影响；酯类成分在高压下会发生变化，但总体变化不显著。

The different hexanedichloromethane volumn ratio effection on molecular weight of,molecular weight distribution and weight percent of lowmolecule of polyisobutene by boron trifluoride initiator was studied in this paper by IR and UV.

研究了正己烷—二氯甲烷溶剂配比对BF3引发体系的聚异丁烯分子量及分子量分布、低分子物含量的影响，给出了BF3引发体系聚异丁烯及AlCl3引发体系聚异丁烯的红外光谱及紫外光谱。

So, by the Diels-Alder reaction of tetraphenylcyclopentadienone, acenaphthenecyclone and benzophenanthrenecyclone with the vinyl groups in C gum, three kinds of polymethylvinylsilicone oil with condensed aromatics are synthesized respectively: polymethylvinylsilicone oil with tetraphenylphenyl groups (called C_1 gum for short), polymethylvinylsilicone oil with acenaphthenyl groups (C_2 gum) and polymethylvinylsilicone oil with benzophenanthrene groups (C3 gum).

根据此原则，利用四苯基环戊二烯酮、苊式环戊二烯酮和菲式环戊二烯酮与C胶上的乙烯基进行Diels—Alder反应，分别合成了三种含稠环基团的乙烯基硅油：四苯基苯基乙烯基硅油(C_1胶)，苊式多苯基苯基乙烯基硅油(C_2胶)和菲式多苯基苯基乙烯基硅油(C_3胶)，并根据~1HNMR谱图上不同氢原子的积分面积计算了三种胶中稠环基团和乙烯基的含量。

Efficacious drugs were made of these species for treatment of cough, phlegm, breathe heavily, especially, to cure lung disease. We have investigated on the Chemical constituents of Adenophora stenanthina subspecies xifengsis collected from Gansu Qingyang, and twenty four compounds were isolated from ethanol extraction by chromatography technigues. Twenty compounds were identified by means of chemical and spectra methods（IR, FAB-MS, EI-MS,〓,〓, DEPT , among which three compounds were new as 3βvanilloyloxy-stigmast-5-ene-7β-one; 3β-Vanilloyloxy-stigmast-5-en-7 β-ol; 3β-vanilloyloxy-stigmast-5-en-7β, 15 〓-diol.

我们对采自甘肃庆阳的西峰沙参Adenophorastenanthina subsp.xifengensis）进行了化学成分的研究，利用现代层析手段从该植物的乙醇浸膏中分离出二十四个化合物，经化学方法和波谱技术（红外，质谱，核磁共振谱）鉴定了二十个化合物的结构，其中三个为新的化合物，它们分别是：豆甾-5-烯-7-酮-3β-香草酸酯；7β-羟基-豆甾-5-烯-3β-香草酸酯；7β，15ξ-二羟基-豆甾-5-烯-3β-香草酸酯。

HCo 〓-catalyzed hydroformylation and isomerization of allene and propyne Allene hydroformylation favors the linear anti-Markovnikov product in high regioselectivity both kinetically and thermodynamically. The origin of this regioselectivity comes from the enhanced stability of the η〓-allylic intermediate (η〓-CH〓CHCH〓 Co 〓.

HCo〓催化的丙二烯和丙炔氢甲酰化反应及异构化反应 HCo〓催化丙二烯氢甲酰化反应的区域选择性主要由不可逆的丙二烯插入步骤决定，动力学和热力学因素都有利于形成anti-Markovnikov中间物种(η〓-CH〓CHCH〓)Co〓，形成Markovnikov中间物种Co〓是不具有竞争性的。

Because of the rapid development of allylation reaction in aqueous media, allylation reaction mediated by new metal systems or metal systems, and its mechanism are reported increasingly.

水相烯丙基化反应由于其发展速度较快，新的金属及金属体系参与的烯丙基化反应以及水相烯丙基化反应的机理研究不断被报道。

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。