先导的

In the forth chapter, the mechanism of pyrimidine benzylamine compounds is studied by the conventional bioassay and biochemical methods based on probe compound 104-4. The results presented here indicated that the addition of 5 mg/L of 3 branched-amino acids to sorghum seedling cultures incubated in the presence of 104-4 completely alleviated herbicide-induced stem growth inhibition, but each of Val, Ile and Leu single is only partly effective in reversing 104-4-induced growth inhibition at the same concentrations.

通过先导结构优化策略的实施，筛选出15个高除草活性的4，6-二甲氧基-2-取代嘧啶苄胺类候选化合物，在此基础上，对一些候选化合物进行作物安全性评价试验，实验结果提示化合物103-1和化合物105-3在低剂量下对某些作物有良好的选择性，可作为优选化合物进入田间小区试验。

Five types of compounds were synthesized via modification of the leading compounds, Mannich bases of cyclopentanones. Among the target compounds, one type was aromatic amine derivatives of a leading compound, three were Mannich bases of a - benzylidene cyclopentanone, the fifth was a Mannich base of a - benzyl cyclopentanone.

以具有抗炎活性的环戊酮Mannich碱为先导化合物进行结构改造，设计合成了一类已知化合物的芳胺Mannich碱衍生物，三类α-苯亚甲基环戊酮Mannich碱类化合物，一类α-苄基环戊酮Mannich碱类化合物。22个目标化合物的结构经核磁共振氢谱、红外光谱和质谱检测确证。

Betulin, a naturally occurring triterpene, available in abundance up to 10% dry weight of bark from white birch bark, seems to be an ideal starting material for the synthesis of betulinic acid.During a discovery effort from natural resources, in order to seek new biologically active compounds, reaearch on chemical modifications of valuable precursors have been demonstrated to be an effective path to resolve the water solubility problem and increase bioavailability.

从自然界寻找先导活性化合物，再进行结构修饰，试图提高其活性，降低其毒副作用，并提高其水溶性，是创新药物的一条重要思路，而且在新药研制中也得到了很好的应用并取得了显著的成绩。

The drug design method based on the target structure is an important means to design lead drugs. Chemogenomics, the combination of combinatory library and high throughput screening accelerates the proceeding of drug research.

摘 要：基于靶标结构的药物设计方法是先导药物设计的重要手段，化学基因组学结合了组合化学和高通量筛选，加快了药物研发的进程。

This provides the theoretical foundation of the syntheses of leadcompounds and exploitation of botanical insecticides for Juglans mandshurica.

为进一步研究核桃楸活性先导物的化学修饰，开发出在实践中具有推广价值的、环境友善型的核桃楸植物源农药打下良好基础。

Tetrahydroisowuinolin derivatives and phthalide derivatives were designed and synthesized on the basis of a PDE4 inhibitor pharmacophore model set up through computer simulation. Some tetrahydroisowuinolin derivatives synthesized were evaluated on their activity against PDE4 for study on the structure-activity relationship.(7-cyclopentyloxy)-6-methoxy-3,4-dihydroisoquinolin-2(1H)-yl(4-hydroxy-3-methoxyphenyl)methanone (155) and Methyl 7--6-methoxy-2-(4-methoxy- benzoyl)-1-phenyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (170) showed good activity against PDE4, which were chosen as the lead compounds to design and synthesize another analogs in order to develop selective PDE4 inhibitors with better activity.

分别设计合成了以四氢异喹啉和氨基苯酞为骨架的两类小分子杂环化合物，并对部分四氢异喹啉衍生物测试了其相关的生物活性，初步确定了其构效关系，发现了两个对PDE4有较好抑制活性的先导化合物(7-cyclopentyloxy)-6-methoxy-3，4-dihydroisoquinolin-2(1H)-yl(4-hydroxy-3-methoxyphenyl)methanone (155)和Methyl 7--6-methoxy-2-(4-methoxy- benzoyl)-1-phenyl-1，2，3，4-tetrahydroisoquinoline-3-carboxylate (170)。

To serve the customs better, SK carries out a strategy of localized service and insists on globally serving perceptions of 'consulting goes first, product is basis, executing key, training ensuring and service value ', and has set up service network, total of 28 directly under branches and provincially strategic partners, and 30 authorized services, with staffs of more than 1000 all over the country, to form a powerful, excellent and highly effective SK service system, so as to provide a security for informationized application of enterprises.

为更好地为客户提供服务，时空实施本地化服务策略，坚持&咨询是先导、产品是基础、实施是关键、培训是保障、服务是价值&的全程式服务理念，建立了遍布全国的服务网络，直属分支机构及省级战略伙伴共28家，授权服务机构30余家，从业人员1000余名，形成强大、优质、高效的时空服务体系，为企业信息化应用提供安全保障。

PAB, isolated from the traditional Chinese medical plant Pseudolarix kaempferi Gorden , was found to be an early pregnancy-terminating agent in 1980s.

在国家973项目的支持下，我们展开了一系列新生血管生成抑制剂的筛选和研究，并得到了几个具有较强抗新生血管生成作用的先导化合物。

In order to search for the new pyrazolyl-heterocycles lead compounds, eight pyrazolyl- were synthesized from 3-ethyl-1-methyl- 4-substituted-5-pyrazolecarboxylic acid chloride and nitrogen heterocyclic rings such as 3-methyl-5-pyrazolone, 1H-3-ethyl-5-pyrazole ester, etc.

为了寻求新的含吡唑双杂环先导化合物，用 4 取代 1 甲基 3 乙基 5 吡唑甲酰氯与 3 甲基 5 吡唑酮、3 乙基 5 吡唑甲酸乙酯等含氮杂环反应得到了 8个新的含吡唑环的双杂环类化合物。

The principle of forerunning duty from law in China to doctor was decided b y s pecially of professional be-havior.

我国法律对医事主体设定的先导义务原则是由其业务行为的特殊性决定的。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。