立体化学的

Chemical structure diagram, description of reaction scheme, or other supplemental information to aid the identification of the substance

应提供已知的立体化学的细节，在结构式中表明是相对的还是绝对的

Understand the basic conceptions on homolysis and heterolysis of covalent bonds, and on the nucleophilic substitution and elimination; Grasp the mechanism and stereochemistry of S N 1 and S N 2 reactions; be capable of judging the stability of carbocations; know the factors that can influence the rates of S N 1 and S N 2 reactions; grasp the elimination reactions of haloalkanes, the mechanism and stereochemistry of E1 and E2 reactions.

了解共价键的均裂和异裂及亲核取代反应的基本概念；掌握 S N 1 和 S N 2 反应机理和立体化学；能够判断正碳离子的稳定性；了解影响 S N 1 和 S N 2 反应速率的因素；掌握卤代烷消除反应， E1 和 E2 反应机理和立体化学。

Compound 3 was obtained from Senecio kaschkarovii for the first time and, Compound 4 is a new compound. Compound 4s absolute configuration had been determined by CD, NMR and NOE.

通过CD谱及NMR、NOE差谱研究了化合物4的立体化学，并按Dreiding models构筑了该化合物分子的立体化学结构，确定该化合物应为Non-steroid型构象。

In the last part, the study of controlling the stereochemistry of the newly formed chiral centers was not successful.

在第四部分，关於控制立体化学的相关研究方面，均无法得到好的结果。

The progress of the optical activity and stereochemistry of bile pigments in recent20 years is reviewed.

本文综述了20年来胆色素光学活性及其立体化学的研究进展，著重讨论了分子内和分子间相互作用对色素构象的选择性及其光活性的影响。

Pasteur, who as a youth discovered stereochemistry, now allied himself with vitalism.

然而现在，这名年纪轻轻便已创立立体化学的科学家却犯下了一个不可饶恕的错误：他成为了活力论的支持者。

In the cyclization process,α-acylamino radicals preferred to attack acylsilanes from the face opposite to the β-substituent, and the stereoselectivity of the bridgehead is excellent. The orientation of the hydroxy group formed in the cyclization process was mainly exo.

生物碱架桥上立体化学的建立，可透过环上取代基立体障碍的影响，使得环化过程只会从立障较小的一面进行，因此可得到单一立体化学的结果，而环化所形成的羟基则是以exo的产物为主。

In conclusion, a catechol moiety is presumably to be essential for its activity and substitution of the p-hydroxybenzyl group at C-1 position with correct stereochemistry in the isoquinoline molecule makes a great contribution to the activation of beta adrenergic receptors.

本实验初步结果发现，对於去甲基乌药碱分子之药效，catechol基是必备无疑；而异喹啉环的碳－1位置上取代的p-hydroxybenzyl基对於药效有非常大的影响；至於其立体化学的配位是有立体选择性的。

A study to determine the factors influencing the stereochemical results has been reported.

有关测定这类立体化学的影响因素的研究，也有报导。

Thestercoselectivity of the reaction of propargylide was different completely from that of the reactionof telluronium 3-trimethylsilylalltide with α,β-unsaturaled ketones and trans-trimethysilylacetylenyl-l-benzoyleyelopropane derivatives were obtained.

发现这一反应的立体化学与同样条件下含硅烯丙基碲叶立德和α，β-不饱和酮反应的立体化学完全不同，得到的是又式-2-三甲基硅基乙炔基-1-酮基环丙烷衍生物。

Cynanchum Lingtai apricot production in the average weight 65 grams, the brightly-colored fruit, juicy rich, sweet-sour taste, sweet from the nucleolus, when the late Qing Dynasty famous Shaanxi, Gansu provinces, the Qing imperial court Tongzhi tribute for years.

灵台生产的牛心杏平均单果重65克，果实色泽鲜艳，汁多味浓，甜酸适口，离核仁甜，清末时就驰名陕、甘两省，清同治年间曾为朝廷贡品。

Chenopodium album,Solanum nigrum, and Amaranthus retroflexus were very susceptible to the herbicides. Polygonum persicaria and Abutilon theophrasti were relatively less susceptible to the herbicides, and Lycopersicon esculentum was not susceptible to it. The relationship between reduction rates of weed biomass and PPM values of weed leaves 2,4, and 6 days after treatment was established.

供试的6种杂草对该混剂的敏感性存在显著差异：红心藜Chenopodium album、龙葵Solanum nigrum和反枝苋Amaranthus retroflexus对该混剂最敏感，ED90值分别为47.65、71.67和29.17g/hm2；春蓼Polygonum persicaria和苘麻Abutilon theophrasti敏感，ED90值分别为96.91、114.20g/hm2；而番茄不敏感。