第二十个

Second, Entropy, proposed by Clausius, a German physical scientist, was first a unit inthermodynamics, and then was applied in many other arenas.

第二，文章通过对熵思想十个方而的介绍，系统地介绍了熵思想；文章还介绍了熵及熵权的基本定理。

Saint Lucia became Taiwan's 25th diplomatic ally.

圣露西亚成为台湾第二十五个邦交国。

It was admitted as the 24th state in 82. Under Spanish control from 7'2 to 800, the area passed to the United States through the Louisiana Purchase of 803. Organized as a territory in 82, Missouri's application for admission as a slaveholding state in 87 sparked a bitter controversy over the question of extending slavery into new territories. The Missouri Compromise of 820 provided for the admission of Maine as a free state and Missouri as a slave state in the following year.

于82年被接受为第二十四个州。7'2年到800年，此地区处于西班牙的控制下，美国于803年在路易斯安那购买行动中获得这一地域。82年成为一个地区。87年密苏里申请以蓄奴州身份加入联邦导致了关于是否将奴隶制扩大到新地区的争论。820年的密苏里协议为次年作为自由州的缅因州和作为蓄奴州的密苏里州加入联邦铺平了道路。

In another three months, the 29th Summer Olympic Games will be held in Beijing.

再过3个月，第二十九届夏季奥运会将在北京举行。

Twenty months later my second son was born. He was also healthy, smart and tall.

二十个月后，第二位儿子出生，也是健康聪明的高个子。

My parents are going to celebrate their twenty-fifth wedding anniversary.

我父母要庆祝他们的第二十五个结婚纪念日。

It has been the twenty-fifth autumn, but still make me so exciting.

已经是生命中第二十五个秋天了，却依然这样容易激动。

Although it's the twenty-fifth autumn, still make me so exciting.

已经是生命中第二十五个秋天了，却依然这样容易激动。

BERITH.-The Twenty-eighth Spirit in Order, as Solomon bound them, is named Berith. He is a Mighty, Great, and Terrible Duke.

第二十八位是Berith，他是个强大的，骇人的公爵。

This work, concentrated on the asymmetric allylation of aldehydes controlled by different chiral auxiliaries prepared from rotational pure tartaric acid, can be divided into three parts.The first part aims to review the developments of chiral drugs and asymmetric synthesis, from which derived the present research topic backgrounds and works.Synthesis and applications of allylation from aldehydes are the second part of the thesis. By optimizing the reaction conditions, such as solvents, temperature, time and chiral auxiliaries like N,N\'-dibenzyl tartamide, N,N\'-p-dimethylphenyl tartamide, N,N\'-o-dimethylphenyl tartamide, N,N\'-o-dichlorophenyl tartamide, N,N\'-a-dinaphyl tartamide, N,N\'-dicyclohexyl tartamide and N,N\'-diphenyl tartamide, ideal experimenttal conditions are obtained according to HPLC monitoring, as well as the auxiliaries\' recoveries experiments. Starting from benzaldehyde and 3-bromopropaldehyde, N,N\'-dibenzyl tartamide is considered the best auxiliary in this reaction.

本文介绍了醛的不对称烯丙基化反应，以光学纯酒石酸为原料，研究了不同构型手性配体在醛的烯丙基化反应中的立体选择性，全文共分三部分十个章节：第一部分对当前手性药物和手性技术进行了概述，并由此展开了本文的研究背景和任务；第二部分为有机合成部分，对醛的不对称烯丙基化反应进行了深入探讨，以苯甲醛为原料对反应条件进行优化，在优化的反应条件下对制备的七种可回收手性酰胺配体(N-苄基酒石酸二酰胺、N-对甲苯基酒石酸二酰胺、N-邻甲苯基酒石酸二酰胺、N-邻氯苯基酒石酸二酰胺、N-a-萘基酒石酸二酰胺、N-环己基酒石酸二酰胺和N-苯基酒石酸二酰胺)进行筛选，优化配体回收实验条件，最终确定出N-苄基酒石酸二酰胺在苯甲醛的不对称烯丙基化反应中具有较大优越性，结晶回收的手性配体光学纯度保持不变。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。