steric hindrance

The stereoselectivity was improved by increasing steric hindrance of the reactions.

通过增加反应的空间位阻改进了反应的立体选择性.

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The electronic effects of the substituents on the benzene ring and the steric hindrance do not significantly alter the reaction time and yield.

反应时间和反应收率不明显受苯环取代基团电子效应及空间位阻的影响。

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And it was found that dioxo-methyl group was a key factor to determine the antioxidant activity of DCLs, because its O and C had rather high net charge and its steric hindrance was rather low.

发现二氧甲基基团具有较大的O原子负电荷及C原子正电荷，且空间位阻较小，因此成为决定五味子素抗氧化活性的关键因素。

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The results indicated that, by using mixed surfactant, the absolute value of ζ potential was enhanced and the static effect and steric hindrance effect of colloidal solution were strengthened as well.

结果表明，在胶体溶液中加入混合表面活性剂后可以提高胶体的ζ电位绝对值，使静电效应和空间位阻效应同时增强。

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The Effect of Steric Hindrance on the Photophysical Behavior of Substituted Styryl Pyrazine Derivatives

结构受阻对取代苯乙烯基吡嗪光物理行为的影响

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The two phen ligands chelating to each Cu(ⅱ) center arrange in almost perpendicular orientation to avoid the severe steric hindrance.

为了减小空间位阻效应，与中心Cu（Ⅱ）离子螯合配位的两个邻菲咯啉配体之间近似呈垂直排列。

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The oxidation peak current of 1,4-DHP is decreased and the peak position is shifted to the positive direction when bound with CT DNA, while the degree of these phenomena is decreased with the increase of the steric hindrance of the substituent at the C-4 position.

1,4-DHP与ct DNA结合后，氧化峰峰电流降低和峰电位正移程度随着C-4取代基的空间位阻增大而减小。

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Results the particles may have higher electrostatic effect by adjusting the pH value of the medium and have steric hindrance effect by adding the surfactants on the previous condition, which prevent the particles from agglomeration.

结果：调节介质的pH值，使颗粒间处于较高的静电效应，在此条件下加入表面活性剂，使颗粒间又具有空间位阻稳定效应，空间位阻稳定效应可阻止颗粒间的团聚。

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Macromolecules cannot approach the ligand owing to steric hindrance of the matrix.

由于载体的立体位阻的关系,大分子化合物不能接触到配基.

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The fact of reaction rate decreasing linear with the steric hindrance of ester groups shows that the formation of ring coordination compound between rare earth ions and salicylate ester takes an important role in the nitrosation reaction.

反应速度随酯基基团空间位阻效应呈线性下降，说明稀土离子与水杨酸酯之间环状配位化合物的形成在亚硝基化反应中起着重要作用。

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Nevertheless , steric hindrance caused by chemical structure reduces the retention time.

药品化学结构引起之立体障碍会降低滞留时间.

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Synthesis and application of lauric acid ester quaternary ammonium salt cationic surfactant in condition of steric hindrance

位阻月桂酸阳离子酯表面活性剂的合成及应用

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The effect of solvents and steric hindrance on the stereochemistry of cyclization is investigated in details.

并且考察了在环合反应中溶剂和空间位阻对立体选择性的影响.

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Compared with straight chain phosphites, caged bicyclic phosphites have great differences in nucleophilic reactions due to the tension and high steric hindrance caused by the caged bicyclic structure.

双环笼状亚磷酸酯类衍生物由于其笼状结构所引起的张力及高位阻性，使得它同一般直链亚磷酸酯类化合物相比，在亲核取代反应性等方面有着明显的不同。

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In the end, the steric hindrance of the substitute was discussed.

最后，讨论了清除过程中取代基的空间位阻效应。

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HTMA cured with epoxy resin gently and slowly, owing to the synergistic effect of steric hindrance effect and stereo-electronic effect.

空间位阻效应及电子效应的协同作用使HTMA与环氧树脂的固化反应速度降低，固化过程中放热量小，放热平缓。

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By introducing the steric hindrance effects of peripheral and axial substitutions, the red-shift and broadening of the bands are weakened as the structure of the thin films become amorphous.

通过加入分子周边取代和中心取代，从而引入空间位阻效应使薄膜的结构变为非定形，表现在其吸收带的线宽变窄，红移变小。

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