查询词典 selectivity

When SiO〓-NH〓-Rh-Co complex was used to catalyze the hydroformylation of methyl methacrylate, an optimal conversion of 93.4% and optimal selectivity of 84.4% for the normal aldehyde were both obtained at Rh/Co ratio of 2/1, which were both higher than that catalyzed by SiO〓-SiNH〓-Rh and SiO〓-Si-NH〓-Co momometallic catalysts. Clearly a synergistic action between Rh and Co atoms presented in the complex.

我们以SiO〓-Si-NH〓-Rh-Co催化甲基丙烯酸甲酯的醛化反应，当催化剂中Rh/Co比为2/1时，催化活性最高，可达93.4％，对正构产物β-甲酰异丁酸酯的选择性达到84.4％，都高于单金属催化剂，表明了金属间存在相互作用。

In order to increase flotation efficiency and selectivity, the method of pre-ultrasonic processing slime before flotation has been proposed.

为了提高煤泥浮选的效率和选择性，提出了在浮选前对煤泥进行超声波预处理的方法。

The selectivity of cheap sodium silicate was promoted greatly after activated in special methods under suitable conditions.

将水玻璃在特定的条件下经过活化以后，抑制作用的选择性大大提高。

Liquid-phase epoxidation of allyl chloride with hydrogen peroxide was carried out over Ti-MWW, a novel titanosilicate with the MWW structure, to synthesize epichiorohydrin selectively and effectively. Ti-MWW proved to be superior to the conventional TS-1 catalyst in both catalytic activity and product selectivity. Ti-MWW prefers aprotic solvents of acetone and acetonitrile, both of which can restrain the solvolysis of epichiorohydrin, whereas TS-1 favors a protic solvent of methanol.

研究了具有MWW结构的新一代钛硅分子筛Ti-MWW催化剂对烯丙基氯液相环氧化高效合成环氧氯丙烷的催化性能结果表明，Ti-MWW的催化活性以及产物选择性均优于传统的钛硅分子筛TS-1，对于Ti-MWW，合适的溶剂为非质子性溶剂丙酮和乙腈，在该溶剂中环氧化物不易发生溶剂化开环反应；而对于TS-1，合适的溶剂是质子性溶剂甲醇，但甲醇可导致醇醚副产物的生成。

During these years (1997-2000) in the research area of annonaceous acetogenins 5 natural products and a number of chiral-pure analogs of annonaceous acetogenins have been synthesized using sugars as the starting materials. Their high activity and selectivity against cell line of colon tumor and a relationship between activity and configuration have been found too. In the respect of inhibitor of sialidase two new methodologies for the synthesis of chiral-pure 3-deoxy-ulosonic acid using hetero-Diels-Alder reaction or asymmetric propargylation as the key reaction were developed. On the topic of anti-leukemia marine natural product clavulactone a synthetic method based on the free radical cyclization and starting from sugar has been developed. In other title of PKC inhibited agent sphingosine a new synthetic route with SN2' as the key reaction has also been disclosed.

项目期间（1997-2000）在番荔枝内酯方面从糖出发合成了五个天然产物和一批手性纯的类似物，它们对肠癌细胞有很高的活性和选择性，并与构型有关；在唾液酸酶抑制剂方面发展了二类全新手性纯高碳糖的合成方法－杂原子D－A反应或丙炔基不对称加成为关键的反应；抗白血病海洋天然产物群柱虫内酯方面研究了由糖出发和自由基环化反应的合成方法；对PKC 起抑制作用的鞘氨醇方面也开创了新的合成途径－由糖出发并以SN2'反应为关键反应。

In high selectivity enrichment culturing process and rapid screening procedure, the succinic acid producers with starchness and saccharide were isolated from bovine rumen.

本研究通过采用选择性较强的富集培养和快速准确筛选程序，从牛瘤胃中分离出适于淀粉质原料的琥珀酸产生菌，并进行相关的生理生化鉴定：通过紫外照射诱变育种得到琥珀酸高产突变株，优化培养基组成并确定最适发酵培养条件。

The conversion of stearic acid reach 52 % and the selectivity of monoglyceric stearate can reach 96 % under the condition: reaction time 10 h, catalyst loading 5 wt %, reaction temperature 110℃.

反应时间10 h，催化剂用量5 wt%，反应温度110℃，十八酸的转化率为52%，硬脂酸单甘酯的选择性达96 %。

The effect of H2SO4 concentration and reaction time on the xylose yield and the selectivity of hemicellulose hydrolysis in corn stover under 121 ℃ was studied by response surface methodology.

通过响应曲面法，研究了反应温度为121℃时，不同硫酸浓度和反应时间对玉米秸秆中半纤维素水解为木糖的产率以及选择性系数的影响。

Simulation results prove that so long as both busbar stray capacitance and sampling frequency satisfy a certain condition, the proposed scheme can judge the fault accurately under various fault conditions. The proposed scheme possesses good selectivity and strong ability of anti-transition resistance, besides, it is more sensitive to the fault occurred at the end of transmission line.

仿真试验表明，只要母线杂散电容和采样频率满足一定的条件，该方法在各种故障条件下均能准确判断故障，具有很好的选择性，并且有很强的抗过渡电阻能力，对末端短路故障的反应灵敏度更高。

Not considering subsample, these two filter banks retain more image details and better direction selectivity.

这两种全相位方向滤波器组不对图像下采样，保留了图像方向的细节信息，具有更好的方向选择性能且在恢复时，不需要重建滤波，方法简单；在对Contourlet变换的分级研究中，建立了一种全相位分级方法，由于全相位子带分解的优异性能，使得这种分级方法优于拉普拉斯金字塔分级方法。

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％。