选择性

Selectivity of acetal was obtained over the Cu/HY-25 catalyst at the temperature of 413K.

通过铜盐与酸功能组分的匹配，以醋酸铜和HY-25分子筛制备的催化剂，在413K生成乙缩醛的选择性大于80％。

Yield of acetate and reaction selection are raised, consumption of acetaldehyde are reduced, and by-products are also reduced.

实施后提高了醋酸收率和反应选择性，降低了乙醛消耗，减少了副产物，取得了良好的效果。

A novel Pd／C catalyst with high activity,high selectivity and good stability developed by our group was used for the hydrogenation of N-（3-nitro-4-methoxyphenyl）acetamide into N-（3-amino-4-methoxyphenyl）acetamide in methanol and water,respectively.

笔者开发了一种高效的Pd／C催化剂，分别选用甲醇和水作为反应溶剂，实现了高活性、高选择性和高稳定性地催化加氢制备N-（3-氨基-4-甲氧基苯基）乙酰胺。

While acetone was used as substrate, the configuration of aldol product was related to the amount of water.

而对丙酮与芳香醛的反应，发现选择性和Aldol产物的构型与所用水量有关。

At this temperature, the selectivity of acrylonitrile is 92.7% and the conversion of acetonitrile is 19.9%.

在反应温度为400℃时，Mn_(0.2)/BaCO_3催化剂上丙烯腈的选择性为92.7%，乙腈的转化率为19.9%。

Conversion and 79.1% ee were obtained for acetophenone under optimized conditions.

实验结果表明，离子液体介质中的纳米钌催化剂体系具有良好的催化活性和对映选择性。

The results indicate that the acetophenone conversion is affected orderly by substrate concentration, reaction time, reaction temperature and yeast concentration.

结果表明，影响苯乙酮转化率的因素依次为底物浓度、反应时间、反应温度和酵母浓度，影响1苯基乙醇对映选择性的因素依次为反应温度、底物浓度、酵母浓度和反应时间。

The results indicated that acetophenone can be reduced by NaBH4/BF3·Et2O wit...

Et2O还原苯乙酮可以获得很高的化学产率和低到中等的对映选择性。

The effects of some factors, such as reaction temperature, reaction time, substrate concentration and yeast concentration, on the acetophenone conversion and- 1-phenylethanol enantioselectivity were investigated by orthogonal experiments.

研究了酵母细胞催化芳香酮的不对称还原反应，采用正交试验综合考察了反应温度、反应时间、底物浓度和酵母浓度等因素对底物苯乙酮转化率和产物1苯基乙醇对映选择性的影响。

The results indicated that acetophenone can be reduced by NaBH4/BF3Et2O with high chemical yield and low to moderate enantioselectivity when amino alcohols were used as catalysts.

结果表明：这些氨基醇催化NaBH4/BF3Et2O还原苯乙酮可以获得很高的化学产率和低到中等的对映选择性。

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％。