查询词典 steric

In the Aldol condensation of acetone with 4-nitrobenzaldehyde, two different hybrid secondary amine-functionalized mesoporous materials displayed enhanced catalytic performance in comparison to primary amine-functionalized materials. The possible reason is that the presence of organic functional groups with larger steric hindrance led to the enhanced catalytic performance of basic amino groups.

在对硝基苯甲醛和丙酮的羟醛缩合反应中，相对于一级胺功能化的材料，二级胺功能化的SBA-15展示了极大改进的催化活性，这可能是由于具有更大空间位阻效应的有机功能团的引人导致了碱性胺中心催化活性增强。

We also explored the structure characteristics inside the C8TES SAM by the AFM scanning experiments, in which AFM cantilever tips with different spring constants were used, as well as the theoretical analysis of the molecular steric during the formation process of C8TES SAM.

论文还通过使用不同弹性系数的悬臂探针的AFM扫描实验和C8TES SAM形成过程中分子空间位阻的分析，对18℃时1×10~(-3)mol／LC8TES-甲苯溶液中C8TES SAM形成过程中内部结构的特征进行了研究。

Both electronic and steric effects were observed for the homo coupling of aryl iodides. Electro-withdrawing and ortho substituents gave desired products in low yields.

在取代碘苯的偶联反应中观察到电子效应和位阻效应的影响，吸电子基取代和邻位取代对反应不利。

Brief probe hybridized with long target DNA, the hybridization position had no effects on the binding amount, but mid-position of hybridization would prolong the hybridization time, which was due to the steric hindrance on the surface.

结合位点不同对杂交量无明显影响，但由于晶体表面DNA空间结构的影响，结合位点位于靶序列中间时杂交时间明显延长。

The coordinated COD of 3 and 4 can be replaced by carbon monoxide to yield the corresponding dicarbonyl species [(C,N-pyN^C-R) M2]BF4 (14, M= Rh; 15, M= Ir). Ligand substitution of 11a by phosphines and azide causes the de-complexation of pyridinyl-nitrogen donor to generate the corresponding carbene rhodium complexes [(C-pyN^C-Mes)RhPR3] (17a, R = Ph, 17b, R = Et) and [RhN3] (19), respectively, indicating the labile nature of steric-hindered pyridinyl-nitrogen donor.

螯合错合物的吡啶配位，可以容易被σ-予体，如卤离子、叠氮阴离子、膦试剂，置换；但是铑与铱金属螫合物与π-酸试剂，如一氧化碳、异腈，则发生COD被置的产物14a与16；与三甲基亚磷酸酯反应时，COD及吡啶均会被取代而得到单芽的三铑-碳烯错合物18；双膦化合物则会取代铑金属上全部的配位基。

The central 5, 5'-disubstituted bipyridine units of each ligand coordinate theNi or Fe ion, while all the terminal 6-monosubstituted bipyridine units of the ligands keep free of coordination, as the result trinuclear triple-stranded helicate 〓 can not form. This is considered to be caused by the steric hindrance of the methylene substituents α to the chelating nitrogens of the terminal bipyridine units and the strain caused by linkage mode.

配体L〓与Ag作用得到〓，两个配体链相互缠绕着两个Ag离子周围形成双股螺旋结构并以头尾式排列(见图3)，由于配体中位于配位N原子α或β位的末端甲基或次甲基取代基的空间位阻阻碍了头对头式异构体的形成，也正是由于配体头尾式排列而使Ag双股螺旋得以形成，这一结果表明该螺旋体的组装过程中自发地采取了空间阻碍尽可能小的那个构型。

The effects of electronic and steric effect of substituted groups, the structure of chiral catalysts and chiral reagents and the reaction system on optical activity of products are summarized.

文章概述了芳香酮取代基的电子效应与空间效应、手性催化剂和手性试剂的结构、反应体系等对产物光学活性的影响，以及全细胞酶、分离酶等不同生物催化体系中芳香酮结构对产物光学活性的影响，并展望了不对称还原的研究及应用前景。

Therefore, the EL spectra of (Znq_2)_4 is wider than that of Znq_2. 4._2 was synthesized. The analysis of molecular spatial structure and the characterization of material performance of_2 and Liq showed that two Liq molecules and two Naq molecules were connected by Na-O-Na bond bridges to form_2. Compared with Liq,_2 exhibits stronger rigidity in planar molecular structure, larger steric hindrance and intermolecular distance, and much smaller molecular polarity, thus resulting in much longer fluorescence lifetime, much higher fluorescence quantum efficiency, wider energy bandgap and better film formability. When used as light-emitting layer in OLED,_2 shows lower formation probability of excited dimmer and exciplex formation than Liq, thus emits bluer light with higher current efficiency than Liq. When_2 ultrathin film is used as electron injection layer in OLED, it exhibits higher current density, higher luminance, lower turn-on voltage and higher current efficiency than Liq ultrathin film for the existence of sodium ions in_2 ultrathin film. 5. The summarization the relationship between molecular spatial structure and material performance of Alq_3,(Znq_2) and Liq, lead the conclusion that the molecular spatial structure of Mq_n affects its material performance in such aspects as the rigidity of planar molecular structure, intermolecular interaction, molecule stacking mode and intermolecular distance.

制备了_2，通过对_2和Liq的分子空间结构与性能进行分析与讨论，发现_2是通过两个Na-O-Na键桥将两个Liq和两个Naq连接构成的，其分子平面结构的刚性程度强于Liq，空间位阻大于Liq，分子之间的距离大于Liq，分子极性远远小于Liq；_2的荧光寿命长于Liq，荧光量子效率高于Liq，成膜性优于Liq；_2的禁带宽度比Liq大，光致发光光谱中_2的最大发射峰较Liq发生蓝移；当_2在OLED中作为发光层时，激发二聚体与激基复合物的生成几率远远小于Liq，发的光比Liq更蓝，电流效率大于Liq；_2超薄膜中有Na离子的存在，与Liq超薄膜相比，当其在OLED中作为电子注入层时，具有更大的电流密度，更高的发光强度，更低的阈值电压和更高的电流效率 5、对上述Alq_3、Znq_2和Liq的分子空间结构与材料性能之间的关系进行了归纳总结，认为Mq_n的分子空间结构主要在分子平面结构的刚性程度，相邻分子之间的相互作用，分子堆叠的方式和分子之间的距离这四个方面影响其性能。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。