查询词典 selectivity

Activity-stability experiment for the liquid phase alkylation of benzene with ethylene was proceeded for 2000hrs, the average values of ethylene conversion, ethyl-benzene selectivity and ethylation selectivity were 100%, 94.5% and 99.0% respectively.

进行了苯和乙烯液相烷基化的2 000 h 活性稳定性试验，乙烯转化率、乙苯选择性、乙基化选择性分别平均为100%、94.5%和99.0%。

The selectivity for K over Na of the low affinity K uptake system in the roots of Puccinellia tenuiflora was approximately similar to that in glycophytes. However, the selectivity for K over Na of high affinity K uptake system in the roots of Puccinellia tenuiflora was much stronger, which indicated that HAK and HKT played very significant roles in the process.

小花碱茅根低亲和性K 吸收系统对K 、Na 的选择性吸收能力与甜土植物大致相同；但其高亲和性K 吸收系统的选择性能力很强，表明HAK和HKT在此过程中起重要的作用。

The temperature and the addition of surfactant can accelerate conversion and selectivity of reaction. Under the conditions of 200℃、0.38MPa、0.06 mol/L、t=4h,the conversion of hexene is 86.32%.Selectivity of 2-hexene and 3-hexene is 30.46% and 57.86%.

结果表明，当表面活性剂的加入以及反应温度的升高，能明显提高反应的转化率和选择性，在200℃、0.38MPa、0.032 mol/L的反应条件下，反应4小时底物转化率为86.32%，3-己烯的选择性为57.86%，2-己烯的选择性为30.46%。

Both catalytic activity and selectivity of Ru(PPh_3)_3Cl_2 were improved in ionic liquid BMImPF_6/DME medium.The conversion of hexene and selectivity ofβ-adduct for the hydrosilylation reaction of 1-hexene with triethoxysilane catalyzed by Ru(PPh_3)_3Cl_2 in ionic liquid BMImPF_6DME (V/V=1/4) medium at 90℃were 100% and 89.0%,respectively.

实验结果表明，在乙二醇二甲醚/离子液体1-丁基-3-甲基咪唑六氟磷酸盐(BMImBF_6)(V/V =1/4)介质中，于90℃下，己烯与三乙氧基硅烷反应的转化率为100%，β加成物的选择性可达89.0%，而用Rh(PPh_3)_3Cl作为反应的催化剂，在纯离子液体BMImPF_6中，就可以高效催化烯烃与三乙氧基氢硅烷的加成反应，过渡金属Rh(PPh_3)_3Cl，Ru(PPh_3)_3Cl_2催化剂/离子液体BMImPF_6催化体系，不仅解决了产物与催化剂分离困难这一难题，同时，离子液体BMImPF_6的存在提高了过渡金属Rh(PPh_3)_3Cl，Ru(PPh_3)_3Cl_2催化硅氢加成反应的活性，特别是β加成物的选择性。

The steoreselectiviy showed the E selectivity in most of cases and Z selectivity was presented in larger substituents like mesityl and 1-naphthyl.

进一步增大烯上的取代基则可以得到Z选择性的烯炔产物。利用如此的方式，也许还可以用来合成含烯炔的高分子。

Secondly, the silver based catalysts modified by phosphorus, zirconium, zinc, potassium and so on using molecular sieve as carrier, which were produced by ion-exchange method, had also good catalytic performance for 1,2-propane glycol oxidation to methylglyoxal. The conversion of 1,2-propane glycol and the selectivity of methylglyoxal were both high, and the impurity such as formaldehyde and acetaldehyde in the product is little. At the condition of the temperature 300 ℃, the molar ratio of oxygen to 1,2-propane glycol 1.7:1, the space velocity 6000h~(-1), and the concentration of 1,2-propane glycol 70wt%, the conversion of 1,2-propane glycol is 90% and the selectivity of methylglyoxal is 45% on the Ag-P catalyst.

其次对采用离子交换法制备的负载在分子筛上的银系催化剂进行了研究，发现此催化剂在助催化剂磷、锆、锌、钾等的作用下对丙二醇的低温氧化脱氢具有很高的活性，可以得到较好的丙酮醛的收率，并且产物中的甲醛、乙醛副产物的量比较低；经过对Ag-P催化剂上反应条件的考察，发现当温度为300℃、氧醇比1.7：1、空速6000h~(-1)、丙二醇浓度为70wt%时，丙二醇的转化率为90%，丙酮醛的选择性为45%。

Cu2-Co2-KBr with high catalytic activity and selectivity shows synergistic effect between metal ions.Under the reaction conditions of mCu(Ac2:mCo(Ac2:m= 0.1:0.5:0.1, n:n=0.14, glacial acetic acid as solvent, overdosage sodium percarbonate, 65℃, the conversion can reach 45.9% and the selectivity for p-methoxy benzaldhyde is about 68.3%.

结果表明，Cu2-Co2-KBr具有较高的催化活性和选择性，体现出金属离子之间的协同作用，对甲基苯甲醚在mCu(Ac2：mCo(Ac2：m=0.1：0.5：0.1，n：n=0.14，冰醋酸作溶剂，稍过量的过碳酸钠，65℃的条件下，转化率可达45.9%，生成对甲氧基苯甲醛的选择性为68.3%。

The selectivity of phenylacetaldehyde is increased when Br〓nsted acidity is getting stronger. The selectivity of benzaldehyde can be increased by increasing the amount of extraframework titanium species.

分子筛的B酸中心强度对产物分布有着显著的影响，B酸越强，苯乙醛的选择性越高，B酸位是催化环氧苯乙烷定向重排生成苯乙醛的催化活性中心；非骨架钛物种的增加有利于苯甲醛的生成。

Copper and cobalt oxides catalyst supported on activecarbon showed specific selectivity for salicylaldehyde and realized74% conversion of o-cresol and 57% selectivity for salicylaldehyde.

论文在液相条件下采用多相催化剂和分子氧，首次实现了催化选择氧化邻甲酚和对甲酚合成相应的羟基苯甲醛。

Results showed N_2O_5/CH_2Cl_2 was a relatively mild system, its nitrating ability of arene was weak, but the para-selectivity of product was satisfactory. Series of ZSM-5 catalysts could improve para-selectivity of product and meanwhile enhance the yield.

结果表明：N_2O_5／CH_2Cl_2是一个相对温和的硝化体系，对芳烃的硝化能力很弱，但产物的对位选择性很好；ZSM-5系列催化剂在显著提高对位产物比例的同时也能提高硝化的产率。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。