查询词典 selectivity

It was found that the allylide of sulfonium salt could react with aryl aldehydes to afford corresponding trans-epoxides in good yield with good trans/cis selectivity and excellent enantioselectivity.

根据反应条件对反应的影响并结合通过单晶测定的反式环氧化产物的绝对构型，我们提出了氢键起主导作用的手性诱导机制。

Both styrene conversion and epoxide selectivity can be obviously improved when a solution of N,N-dimethylformamide and dimethyl sulfoxide with an appropriate proportion is used.

使用适当比例的N，N-二甲基甲酰胺和二甲亚砜的混合溶剂能够显著提高苯乙烯的转化率和环氧化物的选择性。

Comparatively sundried flowers are more suitable to be extracted as an industrial material although the concrete yield of fresh flowers is a little more. At the same time the experiment process fully proves the selectivity of SFE-CO2. Low temperature and low pressure are suitable to extract concrete from natural flavor and fragrance;(2) The materials prepared to extract rutin are the flowers that are gotten rid of concrete by SFE-CO2. The extraction methods include the SFE-CO2 modified by alcohol, the method of hot alkali-precipitate with acid, and alkaly dissolving and acid subsiding combined with microwave or ultrasonic.

66%；产品运用GC-MS做了鉴定；虽然鲜花浸膏产率较高，但干槐花的物料状态更适合工业生产；同时实验过程充分体现了SFE-CO2的选择性，低温低压条件适合香料的SFE-CO2；(2)以超临界CO2(Supercritical CO2，简称SC-CO2)萃取过浸膏的干槐花为原料，运用夹带剂修饰的SFE-CO2、超声或微波或直接加热的碱溶酸沉法提取中药--芸香甙，相比之下，夹带剂修饰的SFE-CO2和超声辅助的碱溶酸沉法提取效果较好，芸香甙提取率分别为2。

In this paper, AM receiver circuit design as the background, in order to improve the sensitivity and selectivity, it is necessary to the use of superheterodyne radio.

本文以调幅接收机电路设计为背景，为了提高灵敏度和选择性，就要采用超外差式收音机。

X-ray analysis with data to 3.2 angstroms reveals that four identical subunits create an inverted teepee, or cone, cradling the selectivity filter of the pore in its outer end.

带3.2埃资料的X射线分析显示，四个相同的亚单元形成一个倒圆锥或锥型，在外端生成细孔的选择性筛检程式。

The ion-imprinted polymer particles have unique selectivity and templet memory even in competing absorption environment.

在构建的竞争吸附环境下，该聚合物仍表现出特异的选择性和模板记忆功能。

The membrane micro-structure and its selectivity could be tailored by controlling the mole ratio of PTMOS to TEOS.

通过控制前驱物中的苯基的含量，即PTMOS／TEOS的比值，可以设计膜的结构和分离性能。

Secondly, preparing terpineol and discussion of its results. It was put up by reaction-temperature, reaction-time, the ratio of catalyst and raw material, the kinds of esterify and dosage, the choice of solvent, catalyst life-span and so on. It was discovered that turpentine transform ratio was 86.29%, the yield ratio of terpineol was 68.89%, the selectivity of solid superacid catalyst was 79.84%.

二，松油醇的制备及结果讨论，从反应温度、时间、物料配比、酯化剂的种类与用量、溶剂的选择、催化剂寿命等几个进行了考察，结果发现反应温度为T3、时间L5小时、酯化剂用F3、物料配比为H3％、溶剂用G等时，松节油的转化率为86.29％、松油醇的收率为68.89％、固体超强酸催化剂的选择性为79.84％。

The yield of borneol and isoborneol was 52.93%,and selectivity for borneol was 60.46%at the conditions of programmed temperatures,reaction time 315 min,saponification time 1h,mass part of catalyst 5%,and terpineol:chloroacetic acid 100∶25.

酯化反应采用程序升温，时间315 min，皂化时间1 h。催化剂用量为松节油质量的5%，松节油∶氯乙酸为100∶25时，龙脑得率为52.93%，正龙脑的选择性为60.46%。

The yield of borneol and isoborneol was 52.93%,and selectivity for borneol was 60.46%at the conditions of programmed temperatures,reaction time 315 min,saponification time 1h,mass part of catalyst 5%,and terpineol:chloroacetic aci...

酯化反应采用程序升温，时间315 min，皂化时间1 h。催化剂用量为松节油质量的5%，松节油∶氯乙酸为100∶25时，龙脑得率为52.93%，正龙脑的选择性为60.46%。

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％。