二化性

The highest ee value of 71% was achieved by using chiral molybdenum 2'-pyridingyl alcoholate complex at 0 ℃. After addition of phase transfer catalyst Bu4NBr, the yield and ee value were remarkably increased.

其中手性吡啶醇二氧合钼在0℃下的对映选择性ee值达到71%；加入相转移催化剂四正丁基溴化铵，催化剂的活性和对映选择性有显著提高，其中手性吡啶醇二氧合钨在50℃下ee值由54％提高到78%。

Two kinds of water-soluble biomimetic chitosan derivatives with a phosphoramide linkage between glucosamine and choline were prepared through Atherton-Todd reaction under the mild conditions, including zwitterionic phosphorylcholine bound chitosan and acetyl-phosphorylcholine bound chitosan with positive charge. The interaction between chitosan derivatives and calf thymus DNA were inversigated by UV alsorption spectra and circular dichroism spectra.

采用Antherton-Todd反应制备了两种水溶性的磷酰化壳聚糖仿生衍生物：两性的N-磷酸胆碱磷酰化壳聚糖和带正电荷的N-乙基磷酸胆碱磷酰化壳聚糖，并用紫外吸收光谱和圆二色光谱研究了两种胆碱磷酰化壳聚糖衍生物与小牛胸腺DNA的相互作用。

The reaction of polyfluoroalkyl iodides with 4-pentenoic acids initiated by sodium dithionite was realized to give polyfluoroalkyl substituted lactones.

我们研究了多氟烷基碘代烷与4-戊烯酸类化合物等在连二亚硫酸钠引发下的反应，得到了氟烷基取代的内酯化合物，我们将该反应称为氟烷基化内酯化反应；并建立了一个利用该反应合成含氟内酯的新方法，首次利用氟烷基化内酯化反应进行高立体选择性双环含氟内酯及手性含氟内酯等的合成，已合成含氟内酯新化合物50余种。

In the first section,the existence of solution for a class of non-linear systems with three -point boundary problem is obtained by applying the differential inequality theory .

在第一部分中，我们应用微分不等式理论证明了一类非线性系统三点边值问题解的存在性；在第二部分中，运用微分不等式理论研究了一类带有转向点的拟线性奇摄动边值问题的非单调内层解；在第三部分中，利用对角化方法研究了一类向量二点或者三点边值问题解的存在性，并获得解及它的一、二阶导数的渐近估计。

Using semi-quantitative RT-PCR, the differential expression profiles of eleven selected genes were confirmed in the ovaries of triploid and diploid. These genes fell in gene categories with a wide range of functions. The results indicated that triploidy affects the dynamic gene regulatory network in triploid ovary. This study established a firm basis for future investigation on characterization of crucial molecular events for normal ovarian development in shrimp.To further dissect exact gene functions for gonad development of shrimp, three differentially expressed genes between diploid and triploid ovary, PCNA (proliferating cell nuclear antigen), CAS/CSE1 (cellular apoptosis susceptibility protein/chromosome segregation 1) and SSRF (spermatogonial stem-cell renewal factor) were characterized on certain aspects.

利用抑制性消减杂交技术，建立了对虾二倍体和三倍体卵巢间的2个消减文库；在正向消减文库(以三倍体卵巢作为实验组，二倍体卵巢作为驱动组)中，鉴定到54个基因；在反向消减文库(以二倍体卵巢为实验组，三倍体卵巢为驱动组)中，鉴定到16个基因；选取11个差异表达的基因，利用半定量RT-PCR的方法对其在二倍体和三倍体卵巢间的表达进行了检测，均能很好地与消减结果相吻合；这些差异基因编码多种功能的蛋白，分析表明染色体的三倍化使三倍体卵巢中的基因调控网络受到了影响；为深入揭示维持卵巢正常发育的关键分子调控事件奠定了基础。

However, analysis of DNA methylation level indicated that the total DNA methylation levels were not significantly different between diploid and autotetraploid. Autotriploid showed a trend of low DNA methylation level. It implied that the alterations of DNA methylation levels were not linear with the autopolyploidy level in watermelon.

有趣地是，二倍体与四倍体西瓜相比DNA甲基化水准却未发生大规模的调整，而三倍体西瓜显示出较为明显的低DNA甲基化水准趋势，表明西瓜同源多倍化过程中其基因组DNA甲基化水准变化与其倍性不成线性关系。

The existence of titanium dioxide and titanyl sulfate reduces the corrosion of zinc deposits.

结果发现：钛的加入能明显提高钝化膜的耐蚀性，这是由于钝化膜中形成二氧化钛和硫酸氧钛，它们掺杂在钝化膜及其腐蚀产物中，有效抑制了锌镀层的腐蚀。

Based on the geological background , ore?deposit and structural geology, the paper analyzed the geological character istics and metallogenic mechanism of the gold deposit and suggests that the deposit occurring in the limestone and metamorphic siliceous rocks in the third litholog ic unit of Devonian Tuokesalei formation is controlled by the Duolanasayi shear zone characteristic of secondary shear deformation, mineralizaion and multiphased vei n mineralization?.

笔者从地质背景、矿床地质，以及控矿构造分析了多拉纳萨依金矿矿床特征及其成矿机理；明确了矿床产于泥盆系托克萨雷组第三岩性段的灰岩－浅变质－硅质岩系，受控于多拉纳萨依韧性剪切带；控矿构造具有二次韧性剪切变形、矿化和多期次脉体矿化的特征，显示出构造活动的多期次性与复杂性，阐明了构造期次与矿化之间的关系。？

MIRANDA MS 2 is an anti-seizing grease based from lithium fatty acid soap and fortified with new types of Molybdenum Disulphide additives. In addition to the inherent anti-wear property and extreme pressure property,it also perform good de-emulsibility, machining stability, thermal stability and anti-rust property.

万灵达 MS2是由脂肪酸锂皂稠化及加入二硫化钼添加剂而配成的防卡咬润滑脂，除固有的极压性及抗磨性外，同时间拥有良好的抗乳化性、氧化安定性、防锈性及机械稳定性。

A chiral phase transfer catalyst, N-benzyl quinine bromide, was synthesized from natural chiral compound. And 2,5-bimethyl-4-(3-nitrobenzene)-1,4-bihydrogenation pyridine-3--4-methyl formate (viz. nitrendipine) was synthesized by this chiral phase transfer catalysis, and characterized by elemental analysis, infrared spectrum,1H nuclear magnetic resornace, and X-ray single-crystal diffraction.Key words: ammonium; chiral phase transfer catalyser; crystal structure

通过对天然手性物质进行修饰合成手性相转移催化剂N-苄基溴化奎宁，并对目标分子2，5-二甲基-4-(3-硝基苯)-1，4-二氢吡啶-3-甲酸乙酯-5-甲酸甲酯进行不对称催化合成，并通过红外光谱和核磁共振氢谱对化合物进行了表征，用X射线单晶衍射法测定了该化合物的晶体结构。

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％。