选择性

Whenpyridine was used as reductive decomposing agent, the expecting cholest-4-en-3,6-dione-22-al was obtained. However, when Zn/HOAc was used to decomposethe ozonide, C-4,5 double bond was further reduced to give cholest-3,6-dione-22-al as main product. 2 For the side-chain construction of compound (1), the solid-liquid phase-transfer Wittig reaction was used. When (3-methyl-2-oxobutyl)-triphenylarsonium bromide was used as reagent, the reaction can be carried out inmild reaction condition and the yield is higher than that when phosphorane wasused.

但使用Zn／HOAc作为分解剂时，却得到其氢化产物胆甾-3， 6-二酮-22-醛；2在甾体支链引入过程中，采用固-液相转移Wittig反应的方法，用(3-甲基)-2-氧丁基三苯基溴化胂作为试剂，反应在非常温和的条件下便可完成，而且产率比传统采用膦烷的方法更高；3在对某些甾酮化合物的选择性还原反应研究时，发现在〓还原体系中，当加入某些金属离子后，反应有更好的区域选择性和立体选择性。

To probe into either the attractiveness to or avoidance from phylloxera of grape rootstocks and cultivars with different tolerance, as well as into the volatile components from their roots, the method of invitro root segment culture was used to investigate the selectivity of Phylloxera viticola Fitch to the roots of grape rootstocks '5BB' and '140Ru' and cultivar 'Kyoho'.

为了探讨不同抗性水平砧木及品种对根瘤蚜吸引及驱避效应以及鉴定挥发性物质组分，采用离体根段培养法测定葡萄根瘤蚜Phylloxera viticola Fitch对砧木5BB，140 Ru及栽培品种巨峰的选择性，发现根瘤蚜对栽培品种巨峰的根段具有很强的选择性，至接种后3d，67.13%的根瘤蚜优先选择巨峰；而对5BB和140 Ru的选择性却很差，分别有15.29%和17.58%的根瘤蚜选择5BB及140 Ru。

The third part elaborates the strategy of selectivity attention and the factors which affect it, then combining with the design of web-based course "The Design of Active Sever Page" which was designed by the writer, elaborates how to apply the strategy of selectivity attention in the the web-based course: 1 design clear navigator; 2 ascertain the target of instruction; 3 take problem as the direction to cause the student's attention;4 the preceding analysises: the analysis of the need of study, the analysis of learner and the analysise of study content; 5 combining muultiual sensorial passages to present the stimulability to course the attention of the learner; 6 enhance the characteristic of the main body to cause the student's attention;7 emphasize the student's position as main body.

第三部分详细介绍选择性注意策略及影响选择性注意策略的因素，之后结合笔者设计的《 ASP 动态网页设计》网络课程具体阐述网络课程中选择性注意策略的应用：1设计清晰的导航；2确定可观察可测量的教学目标；3以问题为导向引起学生的注意；4前端分析：学习需求分析、学习者分析和学习内容分析；5多通道结合呈现刺激，引起学习者的注意；6强化主体的特征引起学生的注意；7强调学生的主体地位。

In a tritrophic system,the acceptability and suitability of five kinds of plants by Cyrtopeltis tenuis Reuter were observed in the laboratory under no-choice and choice situations,respectively.The results from choice experiments with C.tenuis adults showed that there were no significant differences among plant and pest systems except cole+aphids.

在温室内采用笼罩观察，通过选择性和非选择性试验，在两营养级的基础上进一步研究了三营养级体系中烟盲蝽对5种不同植物种类的选择性。

SiO〓 crystal transformation was improved by adding Na〓SO〓, alpha cristobalite but not tridymite was catalytic active support. C〓 selectivity was improved by adding W and P, and suppressed deep oxidation property of SiO〓. W-O in catalyst surface was not active species. The support combined with S, W, P show low activity and high C〓 selectivity.

Na〓SO〓的加入促进了SiO〓晶型的转化，α-方石英是催化活性载体成分，而鳞石英没有甲烷氧化偶联反应活性。W和P的加入改善了C〓烃的选择性，抑制了SiO〓的深度氧化特性；W-O物种不是催化活性物种；由S、W、P及SiO〓组成的载体反应活性较差，但选择性较好；同时S元素对C〓烃的选择性的贡献有限。

D. of the catalyst increased, i. e. the acid volume of the catalyst increased, the conversion for isobutene and the selectivity for trimer increased also, while the selectivity for dimer decreased, and the selectivity for tetramer was almost unchanged.

D。增加时，即催化剂的酸量增加时，异丁烯的转化率和三聚物的选择性也增加，但二聚物的选择性降低，四聚物的选择性则几乎没有变化。

The E-TOF will also be feasible and practical to assist chemists in screening the optimal reaction condition or evaluating the overall efficiency of different catalytic systems for a specific asymmetric reaction.4.For the first time,we explored chiralγ-hydroxy-α,β-acetylenic esters,which were prepared via asymmetric alkynylation,as key intermediates to the synthesis of chiralγ-butyrolactones. This convergent and enantioselective approach to chiralγ-butyrolactones is practical and easily handled with protecting group free.

这一概念包括反应产率、对映选择性、配体用量以及反应时间四个重要反应参数，不仅适用同一反应不同催化体系的横向综合性评价，而且适用于某一特定反应催化体系的优化过程，有助于研究人员选择最佳的反应条件。4、我们发展了以手性γ-羟基-α，β-炔酸酯为关键中间体完成了手性γ-丁内酯类天然产物的对映立体选择性全合成，该关键中间体能够以我们的催化体系方便的对映选择性合成，之后的官能团转换方法成熟，易于操作，无需进行繁琐的官能团保护和脱保护过程，绿色经济。

Moreover,the selective oxidation of primary and secondary alcohols to corresponding carbonyl compounds with the multinuclear copper complexes Cul-Cu4 as catalysts have been conducted using TBHP and O_2/TEMPO,respectively.Among them,the copper complex Cu3 showed the best performance.On the performances of the two classes of oxidants,benzylic and heterocyclic alcohols could be effectively oxidized to carbonyl compounds.Specifically,the secondary alcohols could be effectively oxidized to ketones with excellent selectivity up to 100%in the presence of TBHP and the allylic alcohols could be effectively oxidized to aldehydes in the presence of O_2/TEMPO system.

实验结果还表明，在TBHP或O_2/TEMPO存在下，各配合物催化剂均能使各种取代芳香伯/仲醇以及杂环醇等以不同程度的转化率和选择性转化成相应的醛或酮，其中，配合物Cu3在O_2/TEMPO存在下可使苯甲醇和烯丙醇等以较高转化率和近100%的选择性转化成相应的醛，而对其它芳香醇和脂肪伯/仲醇等的催化性能则较差；在TBHP存在下，配合物Cu3则可使1-苯乙醇和其它仲醇以较高转化率和近100%的选择性转化为相应的酮，但对各类其它伯醇选择氧化的性能相对较差。

Its very difficult to support metal on the surface of crude CNTs. Compared with Pt/C,Pt/CNTs have higher performances in term of efficiency and selectivity. It can be concluded that the interaction between metal and CNTs favors both the high activity and selectivity in cinnamaldehyde hydrogenation.

Pt/CNTs在选择性肉桂醛的选择性加氢中表现出很高的加氢活性和选择性，这是由于纳米碳管外表面独特的结构以及纳米碳管和金属之间相互作用的结果。

A valve of cleanable design capable of maintaining unfavourable conditions for microbial activity on the downstream side and/or outlet of the valve, said valve comprising: A smooth and contoured body ( 5 ) with an integral upstream connector ( 1 ), downstream connector and defined fluid flow path; a flexible sealing membrane ( 9 ) being: selectively moveable into contact with the valve body to close the valve; selectively moveable out of contact with the valve body to open the valve; selectively operable to a range of positions to vary the flow rate of fluid through said valve; a defined internal shape that allows the fluid to drain out of the valve body; an elongated heater ( 7 ) secured into the valve body in a location so as not to be contact with the fluid or disrupt the internal smooth and contoured body, the heater being operative to heat the valve body to a predetermined temperature.

一种清洁设计阀，它能够在阀的下游侧和/或出口维持微生物活动的不利条件，所述的阀包括：一个平滑仿形主体(5)，它具有整体式的上游连接器(1)、下游连接器和确定的流体流动路径；一个柔性密封膜(9)，所述的密封膜：可以选择性地移动以便与所述阀体接触，从而闭合所述的阀；可以选择性地移动以便不与所述阀体接触，从而打开所述的阀；可以选择性地操作到一定范围的位置以改变通过所述阀的流体的流速；一个确定的内部形状，所述的内部形状允许流体从所述的阀体上排出来；一个细长的加热器(7)，它固定在所述阀体内的一个位置，以使加热器不与流体接触，或者说加热器不扰动内部平滑的仿形体，所述的加热器可以操作以加热阀体到预先确定的温度。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。