查询词典 selectivity

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％。

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.

研究了甲醇与环氧丙烷在固体碱催化剂MAF存在下非均相合成丙二醇甲醚的过程。

Effects of sonic factors, including dosage of catalyst, calcination temperature of catalyst, nitrated reaction time and recovered catalyst, on the selectivity of toluene in mononitration at the presence of silicotungstic acid catalyst were studied by gas chromatography.

通过气相色谱研究了诸如催化剂用量、催化剂焙烧温度、硝化反应时间、硝化反应温度及催化剂的重复使用等因素对甲苯硝酸硝化区域选择性的影响。

In a monophase microemulsion where the oil phase was replaced by an ionic liquid, high ortho-selectivity of nitration of phenol can be achieved.

在以离子液体取代庚烷形成的单相微乳液体系中，则可以获得较高的邻位选择性。

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。

Although multidentate heteroatomic could catalyse high selectivity of α-olefin such as 1-hexene and 1-octene,these ligand usually use expensive co-catalyst such as MAO,so it hardly has broad application in α-olefin field.

但由于多齿杂原子配体一般需由价格相对昂贵的烷基铝氧烷，特别是MAO的活化才可进行高效催化反应，因此长期以来多齿型配体难以得到广泛应用。

The microwave-assisted reactions could be finished within several minutes to give high conversion and selectivity.Substrates whose aryl groups were substituted phenyl or naphthyl groups were more suitable in this reaction.

以TfOH为催化剂，在优化的反应条件下，大部分反应都可在数分钟内完成，该反应对于芳基是取代苯环或萘环的的底物效果较好，能得到较高的原料转化率和产物选择性。

METHODS:The neonatus with obstruction of lacrimal passage and dacryocystisis were given homologous treatment such as extrusion,massage and rinsing lacrimal passage weekly.114 cases(169 eyes) with severe infection and mass purulent secretion underwent bacteria cultivation and selectivity medication combined with rinsing and probing after antimicrobial susceptibility test.

对单纯泪道阻塞及泪囊炎的新生儿采用相应的泪道挤压、按摩及生理盐水每周冲洗泪道。对严重感染冲洗伴有大量脓性分泌物的新生儿做细菌培养加药敏试验后选择用药合并冲洗、探通等方法治疗114例169眼。

The experiment results show that the yield of hexane catalyzed by the nano-fibrous catalyst was 4.7 times higher than that of PdCl_2/γ-Al_2O_3 catalyst. The hydrogenation ofα-tetradecylene, cyclohexene, nitrobenzol and styrene by the nano-fibrous catalyst was also studied, the selectivity to primary products of the hydrogenation of cyclohexene, nitrobenzol and styrene was 100%.

苯乙烯-丙烯腈共聚物负载纳米钯超细纤维形态催化剂在常温，氢气压力101.3Pa下催化α-己烯加氢时表现出很高的活性，催化剂PSAN-Pd10催化氢化α-己烯选择生成正己烷的产率在150 min就达到87%以上，与无机物负载的催化剂相比，加氢效果有显著提高，并且催化剂的重复使用性较好。

In the presence of catalytic rhodium acetate, ethyl 2-diazo-3-oxo-per fluoroalkanoates, reacted readily with nitriles to give a series of 5-fluoroalkyl substituted 1, 3oxazoles with high regio-selectivity through a metal carbenoid intermediate. The reactions of carbenoids with noncyclic vinyl ethers or cyclic vinyl ethers afforded dihydrofuroates in good to excellent yields. Interestingly, only vinyl C-H insertion compound was obtained concerning of the reaction of carbenoids with 2, 5dimethylfuran due to the steric hindrance of methyl group

醋酸铑分解2-重氮-3-氧代-全氟羧酸乙酯形成的金属卡宾作为1，3-偶极体，可以与一系列芳基或烷基取代的腈反应，高度区域选择性地生成一系列4-乙氧羰基-5-氟烷基取代的噁唑化合物；也可以与富电子的链状和环状的烯基醚反应，以优良的产率得到一系列氟烷基取代的二氢呋喃类化合物；而与2，5-二甲基呋喃的反应，由于甲基的位阻作用，只得到金属卡宾对呋喃3-位烯基碳氢键插入产物。

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％。