选择性

In the forth part, in the presence of chiral phosphoric acid, highly enantio-enriched (up to 98% ee)α-aryl glycine derivatives could be synthesized via asymmetric transfer hydrogenation of the α-aryl imino esters using Hantzsch ester as the hydrogen source.

第四部分工作中，利用Hantzsch酯作为氢源，高对映选择性地实现了手性磷酸催化芳基酮酸酯亚胺的不对称仿生氢化反应，以最高98％的对映选择性得到苯甘氨酸衍生物。

As a part of this key program from China Natural Science Foundation, this research focuses on the electrochemical reactions and oxidization products on the surfaces of jamesonite and marmatite, and on the change of their interfacial structures and their electrochemical mechanisms by various methods of thermodynamic, electrochemistry (such as Tafel, constant potential step, cycle voltammetry, AC impedance) and IR, UV spectra when the collectors, adjusting reagents act with the sulfide minerals in the flotation system so that the electrochemical conditions to float selectively the minerals can be decided.

本研究作为该国家自然科学重点基金项目的一部分，采用热力学、电化学(Tafel、循环伏安、恒电位阶跃和交流阻抗法)以及光谱等多种研究手段，集中研究了浮选体系中脆硫锑铅矿、铁闪锌矿表面的电化学反应及氧化产物，研究这两种矿物与捕收剂、调整剂相互作用时的界面结构变化及电化学机理，阐明了使药剂选择性捕收或选择性抑制这些硫化矿物的电化学条件。

The regioselectivity observed experimentally is predicted correctly by theoretical calculation and is determined kinetically.

计算结果不仅正确预测了实验所发现的完全的区城选择性，而且表明这种选择性由动力学因素所决定。

Structure preferences of megalopae and first juveniles decreased consequently among grassy type, cavity type, knuckling type shelters and also decreased with increasing sizes (5, 7, 10 mm).

其中，对草丛型、洞穴型和折角型隐蔽物的选择性依次降低，对5.7和10mm隐蔽物的选择性也依次降低。

The dissertation mainly consists of two parts:1. The Reaction Chemistry of Alkynes under Palladium Catalysis Part 1 studies the reaction α,β-unsaturated carbonyl compounds with alkenylpalladium intermediate generated by nucleopalladation, and discovered 1 the Pd-catalyzed tandem addition reaction of halides, alkynes and α,β-unsaturated carbonyls,2 the four-component tandem addition reaction of halides, alkynes and α,β-unsaturated carbonyls, 3 the tandem intramolecular oxypalladation-conjugate additionreaction of alkynoic acids with α,β-enals. These new reactions provide notonly efficient highly stereoselective methods for the synthesis of γ,δ-unsaturated,polyunsaturated carbonyl compounds and γ-lactonic aldehydes, but also thebasic transformations for a number of C-C bond formation reactions which can be usedto design synthesis of many acyclic, cyclic or polycyclic compounds.

本论文的主要工作分为两个部分：一、钯催化下炔烃的反应化学在本小组前人工作的基础上，我们详细研究了炔烃亲核钯化产生的烯基钯中间体与α，β-不饱和羰基化合物的反应，发现两价钯催化下卤离子-炔烃-α，β-不饱和醛酮的串联加成反应、卤离子-炔烃-α，β-不饱和醛酮的西组分串联加成及炔酸分子内氧钯化-串联Michael型加成反应；由此发展了γ，δ-不饱和醛酮、多不饱和羰基化合物和带有醛酮基侧链的γ-丁内酯衍生物的高立体选择性合成方法，这一过量卤离子存在下的烯基钯对α，β-不饱和羰基化合物共轭加成反应的发现，为大量碳-碳键形成反应的实现提供了基础，使我们能够从这一基本反应出发，设计和开发多种分子内、分子间的碳碳成键反应，以好的立体、区域选择性组建开链、环状及多环类型的化合物。

A polar sensitive probe with selective marks prepared by the invention can be used for compounds comprising mercapto. Owning to the introduction of the maleimide group, the probe can be used for the measurement and research of marks of biomacromolecules that comprise the mercapto and adjacent regional polarity change situations of the mercapto, in particular to the research of the selective marks of the mercapto and the adjacent regional polarity change situations of the mercapto in protein.

本发明制备出一种能够用于含有巯基的化合物的选择性标记的极性敏感探针，该探针由于马来酰亚胺基团的引入，可以用于含有巯基的生物大分子的标记及巯基附近区域极性变化情况的测定和研究，特别是蛋白质中巯基的选择性标记和巯基附近极性变化情况的研究。

Influences of reaction temperature, catalyst concentration, molar ratio of methanol to propylene oxide and reaction time on conversion of propylene oxide, yield and selectivity of propylene glycol monomethyl ether were studied.

在反应温度为120～130℃、催化剂用量为0.20%～0.30%、甲醇与环氧丙烷摩尔比为3/1～5/1的反应条件下，环氧丙烷的转化率在98％以上，丙二醇甲醚的选择性达95％，收率达93％，产品中伯醚的选择性为92％～93％。

First of all, a monophase microemulsion was prepared with Triton X-100 as surfactant, and the nitration of phenols by concentrated nitric acid in the systems was studied. The influence of the mass fraction of nitric acid, oil/water volume ratio, reaction temperature and other factors on the reaction conversion and selectivity was examined.

首先在非离子表面活性剂Triton X-100形成的单相微乳体系中，用浓硝酸对苯酚进行选择性硝化反应，研究了硝酸的质量分数、微乳中油/水比、反应温度等因素对反应转化率及硝化选择性的影响。

The analytical results have shown that p ro ducts mainly consisted of some monosubstituted, disubstituted and a few trisub stituted naphthalenes. Except the low activity of HZSM-5 catalyst, all other z eolite catalysts have higher activity. HY and Hβ catalytic activities were the highest, and their naphthalene conversions attained to 79.12 and 55.79 percent respectively, but their selectivities for 2-isopropylnaphthalene, 2,6-diisopropylnaphthalene(2,6-DIPN) and 2,7-diisopropylnaphthalene ( 2,7-DIPN) were too low. ZM catalysts had good activity and much better selecti vity, especially for ZM4-3, of which its 2,6-DIPN/2,7-DIPN ratio was 2.97. Th er efore, some zeolite catalysts are recommended for shape selective isopropylat ion of coal tar naphthalene.

研究结果表明，煤焦油萘异丙基化产物主要由一取代萘、二取代萘以及少量三取代萘组成；除HZSM-5活性较低以外，其它催化剂均有较高的反应活性，其中HY和Hβ反应活性最高，萘转化率分别达75.15％和55.96％，但β位产物的选择性较差；ZM类催化剂既有一定的活性，又有较高的β选择性，是萘择形异丙基化反应理想的备选催化剂。

The DielsAlder reaction of myrcene and acrolein over ZnCl2/NaY prepared by solidstate interaction under microwave irradiation, conventional heating physical mixture, and over ZnNaY prepared by ion exchange in solution was studied.

比较了微波固相法、普通加热法和简单混合法制备的ZnCl2／NaY及溶液离子交换法制备的ZnNaY在月桂烯与丙烯醛DielsAlder反应中的催化性能，发现微波固相法制备的催化剂表现出最高的环加成选择性和区域选择性。

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％。