取代

With the increasing of the concentration of alkali, the content of insolubility of the product reduces initially but increases later, the DS of product increases initially then reduces later. The product has good solubility and high DS at 10% content of alkali. The insoluble product reduces at initially and then keeps stability later with the time of basification extending. With the increasing of the content of water in system, theinsolubility of the product reduces initially and then increases later.

随着碱浓度的增加，产物中水不溶物含量先降低后增加，取代度先上升后下降，在10％时，水溶性最好，取代度最高；延长碱化时间，产物中水不溶物含量下降，之后趋于稳定；提高反应体系中水的含量，产物中水不溶物含量先降低后增加，在7％时，水溶性最好，延长分散时间，产物中水不溶物含量下降，取代度提高；醚化剂以少量多次的方式滴加，产物水溶性好。

It was pointed out that introduction of cyano group into chain of the energetic binder could improve mechanical properties of solid propellant with it.

分析了3，3 双取代氧丁环上两个取代基的类型对其均聚物聚集态的影响，认为在3，3 位进行不对称取代可获得液态含能粘合剂。

According to the crystal structure of the n=1, 2 and 5 compounds, the structural principle of this family was proposed, which is based on alternate stacking of close-packed arrays and graphite-like sheets.

n=2和5化合物中的La也可以部分被其它稀土离子所取代，但相对于n=1化合物而言要困难一些，其中的La只能部分被取代，即使Nd和Sm也不能完全取代形成这两种结构类型的化合物。

These challenges are mainly reflected in three aspects:to replace reasonableness with symmetry,logic with context,and realism with constructionism.

这种挑战主要体现在三个方面：以对称性取代合理性、以发现的语境取代辩护的逻辑、以建构论取代实在论。

The factors such as conjugate framework withsmall conjugation energy, central asymmetry, long conjugate chain,introduction of electron donors-acceptors, strong electron-donating orelectron-withdrawing abilities, long distance between electron donors andelectron acceptors, good coplanarity and so on lead to high third-order optical nonlinearities.

离域能小的共轭骨架，非中心对称结构，长的共轭链，吸供取代基的引入，取代基强的供电子性或吸电子性，长的吸供电子取代基之间的距离，以及良好的共平面程度等因素有利于获得较大的三阶非线性光学性能。

In our research on study chemical reaction of active methylene compounds and brom-acetophenone. Because of brom-acetophenone is compound that contain carbonyl and halogen ,which will take place electrophilic substitution and nucleophilic addition. When active methylene compounds are ethyl acetoacetate and β-diketone, controlling reaction condition, we have found that mono-substitution's production and di-substitution's. production is isolated; active methylene compounds are acetoacetanilide and acetoacetanilide derivate, pyrrolidin-2-one derivants were obtained by substitution and close-ring reaction .but there is no report about it.

本文是让活泼亚甲基类化合物与溴代苯乙酮发生化学反应，由于溴代苯乙酮是含有羰基的卤代烃结构，它可以发生亲电取代和亲核加成反应，当活泼亚甲基类化合物为乙酰乙酸乙酯和β-二酮时，控制反应条件可以发生单取代和双取代两种产物；当活泼亚甲基类化合物为乙酰乙酰芳胺类化合物来反应时，溴代苯乙酮中的羰基与氨基会发生分子内的关环反应生成吡咯烷-2-酮衍生物，这在以前的研究中是没有发现的。

In previous work of helicid's structure modification show that 4 substituted groups of helicid are some ordinary acyclic and substituted aniline group, and it had no heptad heterocyclic substituted group.

在前期的豆腐果苷结构修饰工作中，豆腐果苷4位取代基多为一些简单的脂肪族、取代苯胺基等，尚无七元杂环作为取代基的此类化合物。

The results indicate that thermal stabilities and decomposition mechanisms of the title compounds derived from the BDE, Ea and static electronic parameters are basically consistent. Homolysis of the N—NO2 bond is the initial step in the thermolysis of the title compounds, the meta-isomers are more stable than the para-isomers, and the ortho-isomers are the most sensitive.

结果表明，由BDE、Ea和静态电子结构参数推断的标题物热稳定性和热解机理的结论基本是一致的，N-NO2键均裂是标题物的热解引发步骤，间位取代异构体较对位取代异构体稳定，而邻位取代的异构体稳定性最差。

These mutations greatly changed the level of protein synthesis, lipogenesis and JAK2 phosphorylation stimulated by GH, although they did not affect the expression of the GHR and ligand binding.

研究结果表明豚鼠GHR中的一些氨基酸残基的取代并不影响生长激素通过它而诱导的细胞事件，而另外一些氨基酸残基的取代，例如168位的酪氨酸和332位的丝氨酸分别用在其它种属GHR中高度保守的精氨酸和酪氨酸的取代后，则明显地影响着豚鼠GHR介导的GH诱导的生理效应。

The initial SAR studies indicated:(1) the presence of a linker of methene at the N-1 may be beneficial to anti-HIV activity, while longer chain could enhance toxicity;(2) substituted phenyl at the C-2 could reduce toxicity;(3) 6-substituted benzimidazoles generally showed higher anti-HIV activity than 5-substuted ones;(4) the presence of a halogenated benzyl ring at the N-l would enhance anti-HIV potency and decrease cytotoxicity.

初步构效分析提示：(1)苯并咪唑环1位侧链间隔基为亚甲基时活性最好，侧链延长，毒性增大；(2)苯并咪唑2位侧链无间隔基毒性相对较低；(3)苯并咪唑6位取代活性高于5位取代；(4)苯并咪唑1位芳环用卤素取代，毒性明显降低。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。