descending chain

Some important microbial steroid biotransformations such as side chain cleavage and hydroxylation were reviewed, including their mechanism, development and applications.

对几种重要的甾体微生物转化反应如甾体边链降解、甾体羟基化反应的机理及其发展与应用作了概述 ;同时也介绍了固定化微生物细胞、非水溶液中酶催化反应及混合发酵等微生物转化技术在制药工业中的应

In order to solve the problem whether to keep the hole and block the leakage or protect the permeability of the formation,we propose the use of such polymers as Na-CMC,guar gam and konjaku flour to develop the temporarily blocked drilling fluid combined with the chain scission and degradation mechanics in modern biology.

针对钻井工程中出现的护壁堵漏与保护地层渗透性的矛盾,提出了利用羧甲基纤维素钠、胍尔胶、魔芋等聚合物,并结合现代生物技术中聚合物的断链降解原理,开发出适合于石油、天然气、地下水等钻井领域的自动降解无伤害钻井液——暂堵型钻井液,与传统的暂堵剂不同,它在钻进完成后不需要采用解堵工艺,如压力解堵、酸化解堵、油溶解堵、破胶等,从根本上改进了解堵工艺;分析了暂堵型钻井液的基本原理和两种典型聚合物的酶降解原理,并介绍了室内的粘度实验、渗透性恢复测试实验和在甘肃张掖和广西柳州的现场试验;理论和实践均证明,暂堵型钻井液能自动降解,对产层无伤害,在进行有效护壁堵漏的同时,还能在可控制的时间内显著地恢复地层的渗透性,因此具有推广价值。