活性中心

Therefore, we suggest that for heptane larger surface area is beneficial for higher photocatalytic activity.

而在降解甲苯的过程中，会生成反应活性很低的中间产物，这些中间产物覆盖在样品表面的活性中心，会影响其后进行的光催化反应。

It was found that the main active center is the iron ions which are in the exchange sites in addition to heteroatom FeZSM-5 itself.

进一步研究发现杂原子FeZSM-5分子筛催化剂上主要活性中心是处在阳离子交换位上的铁离子，同时，由于铁原子进入分子筛骨架，使杂原子FeZSM-5本身也具有一定的反应活性。

The substituted half-sandwich titaconece with bulky alkoxyl group [CpTiC1〓 or CpTi 〓] or indene ring can not be fluorinated by BF〓·Et〓O under the selected condition, but still coordinates with the BF〓, this coordination then enhances the steric effect that stabilizes the precursor and hinders the reduction of the Ti to the Ti species, reflected in the decrease in polymerization activity.

但是这个转化受主催化剂分子的空间位阻和聚合反应温度的影响，当主催化剂为大位阻的烷氧基取代茂钛络合物或茚钛络合物时，在一般的聚合温度下BF〓不能对它们进行氟化，但可以和其中的OR配位，这种配位进一步加剧了空间位阻，从而阻碍了活性中心的形成，导致催化活性的下降。

However, it is hard to prepare high valent Mn complexes with ligand with only neutral chelating nitrogen atom of two dpa arms in 〓. In order to get a Mn dimmer complex with high oxidation states of manganese to increase the possibility of storing more oxidizing equivalents necessary to oxidize water evolving oxygen, some N atoms are replaced by anionic phenolate groups.

本文以高价金属的稳定、氧化还原性能的改善、各金属离子之间联系的增强等作为主要研究内容，来改进以往模型中金属价态较低，氧化还原电位高，不利于形成氧化活性中间体；多核配合物的研究较少，且各金属活性中心相互协同作用弱等问题。

Two reasons can be explained the improvements of catalytic activities after the addition of Ce. One is the increase of the thermal stability of Ni-B and Ni-P nanoamorphous alloys, which retards the nanocrystalline Ni to aggregate during the exothermal reaction of benzene hydrogenation. The other is to make their grain sizes smaller, thus it increases the number of activity center in unit mass.

说明加入Ce提高催化活性的主要作用有两方面，一是提高Ni-B和Ni-P纳米非晶态合金的热稳定性，抑制催化苯加氢反应时大量放热促使纳米晶Ni的聚集长大；二是使生成的Ni-B和Ni-P纳米非晶态合金颗粒更为细小，从而增加单位质量样品的活性中心数量。

One route was that the amino-groups on the silica gel were transformed to tertiary amines by Eschweiler-clarke reaction that amine-groups react with formaldehyde and methanoic acid to prepare tertiary amines; the silica gel intermediates with tertiary amine groups reacted with chorohydrocarbons to prepare insoluble silica gel quaternary ammonium salt bactericides. Another route was that the amino-groups on the silica gel reacted with excessive chlorohexadecane; the preparing intermediates were quaternized with iodomethane to obtain insoluble silica gel quaternary ammonium salt bactericides.

一条路线是根据埃施韦勒-克拉克(Eschweiler-clarke)胺甲基化反应，进行胺基叔胺化反应，制成带有叔胺官能团的硅胶中间体，此中间体上的叔胺与卤代烷反应生成杀菌活性官能团季铵盐，制成硅胶类水不溶性季铵盐杀菌剂；另一条路线是带有胺反应活性中心的硅胶与过量正氯代十六烷反应，得到的中间体再用碘甲烷季铵化，得到最终产品——水不溶性季铵盐杀菌剂。

The apparent electron transfer rate constants kapp of azobenzcne to the underlyingelectrode are found to fall off exponentially with increasing the length of alkyl chain spacers. Theelectron tunneling constant P for the electron transfer in the present systenl are estimated to be1.35±0.20 per CH2 from the logarithndc k.p. versus n (nunther of methylenes in the alkyl chainspacer) plot.

而利用电化学活性的自组装单分子膜进行这方面的研究有其独到的优点，可以在分子水平上设计和改变电子转移距离以及电活性中心所处的微环境，为考察界面电化学的一些基本问题，例如电子转移速度与距离的关系、界面结构的影响等＊－q提供了较为理想

Second, residues in the reactive site of the inhibitor were replaced by the consensus substrate recognition sequence of furin, namely, Arg at P_1, Lys at P_2, Arg at P_4 and Arg at P_6. In addition, the P_7 residue Asp was substituted with Ala to avoid possible electrostatic interference with furin inhibition. Finally, the extra N and C terminal residues beyond the doubly conjugated disulfide loops were further truncated. However, all resultant synthetic peptides were found to be temporary inhibitors of furin and kexin during a prolonged incubation, with the scissile peptide bond between P1 and P'1 cleaved to different extents by the enzymes.

高活性、低分子量的furin酶抑制剂有可能发展成为新型的抗细菌内毒素和抗病毒感染的药物，我们以绿豆胰蛋白酶抑制剂Lys片段长链22肽为模板，设计了一系列能抑制furin和kexin活性的突变体，采用如下三种方法逐步优化：一、去除Lys片段长链三对二硫键中的一对，用Ser替换Cys，减少可能存在的二硫键错误配对；二、抑制剂的活性中心根据furin底物的专一性逐步改变，即P1、P2、P4和P6位分别变为Arg、Lys、Arg和Arg，同时为了避免P7 Asp和P6 Arg之间可能存在的相互作用，将P7位Asp替换为Ala；三、将两对二硫键形成的双环的外面5个氨基酸残基去除。

The results of catalytic performance showed that chromium oxide has certain ammonia decomposition activity.

将氧化铬材料用于氨分解反应，发现氧化铬具有一定的氨解活性，在氨分解过程中，催化剂的组成发生了变化，氧化物部分氮化，氨解性能并没有明显的变化，表明氮化铬是氨解反应的活性中心。

The different catalytic activity of the catalysts with various pretreatments is attributed to the variant population of Pd〓 sites.

预处理对催化活性的影响体现在活性中心Pd〓在催化剂中所占比例不同。

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％。