酯

Furthermore, the ability of betulinic acid to induce apoptosis in melanoma and other cell types and the favoral therapeutic index suggests that betulinic acid is an attractive and promising antitumor agent.

虽然白桦酯酸存在于很多植物种类中，但其普遍含量很低，由于其巨大的研究价值，仅靠植物提取已经不能满足越来越多的研究需求，与白桦酯酸结构很相近的化合物白桦酯醇，在白桦树皮中含量高于10%，而白桦又是北半球数量丰富的树种。

Reaction coordinate calculations show that for all of these phosphodiesters the alkaline hydrolysis follows a one-step bimolecular mechanism initialized by the attack of hydroxide ion at the phosphorous atom of the ester.

反应坐标计算表明所有这些磷酸酯的碱性水解均遵循一步历程双分子反应机理，磷酸酯的水解由氢氧根对酯上的磷原子的亲核进攻开始。

Reaction .coordinate calculations show that for all of these phosphodiesters the alkaline hydrolysis follows a one-step bimolecular mechanism initialized by the attack of hydroxide ion at thephosphorous atom of the ester.

反应坐标计算表明所有这些磷酸酯的碱性水解均遵循一步历程双分子反应机理，磷酸酯的水解由氢氧根对酯上的磷原子的亲核进攻开始。

Thus, a stable, homogeneous melt solution is obtained from a solid mixture comprising 4,4'-biphenol(mp 282-284 DEG C) at a temperature of about 200 DEG C using either diphenyl carbonate or bis carbonate as the diaryl carbonate component.

因而，在约200℃的温度下使用碳酸二苯酯或碳酸二酯作为碳酸二芳基酯组分，由含有4，4′-二酚(mp282-284℃)的固体混合物获得稳定、均质熔体溶液。

Results: Reaction of apinene and anhydrous oxalic acid afforded bornyl oxalate smoothly and borneol was obtained from bornyl oxalate by saponification with NaOH solution.

结果：酯化反应能顺利进行生成草酸冰片酯，草酸冰片酯和NaOH发生皂化反应后得到冰片。

A salt of bromic acid.A white, odorless, tasteless crystalline ester, ethyl-para-aminobenzoate(C6H4NH2CO2C2H5), used as a local anesthetic.

苯坐卡因，对氨基苯酸乙酯一种白色、无嗅、无味的晶体酯，对位氨基苯甲酸乙酯，（c6h4nh2co2c2h5），用作局部麻醉剂

Methyl-2,3,5,6-tetrafluoro-benzene methanol was synthesized by chlorination, acylation, fluorination, esterifica- tion, reduction, bromization, reduction from terephthalic acid. Tefluthrin was obtained from-(1RS,3RS)-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cycolpropa-necarboxylate acid by reacting with 4-methyl-2,3,5,6-tetrafluoro-benzene methanol.

以对苯二甲酸为原料，经氯化、酰氯化、氟化、酯化、还原、溴化、还原七步反应合成了4-甲基-2，3，5，6-四氟苄醇，甲基苄醇与-(1RS，3RS)-3-(2-氯-3，3，3-三氟丙-1-丙烯基)-2，2-二甲基环丙甲酸一步酯化合成了七氟菊酯。

The main products are: phosphorous trichloride 300,000 tons / year, phosphorus oxychloride 100,000 tons / year, phosphorus pentachloride 50,000 tons / year, 10,000 tons trichloroisocyanuric parathion / year chloromethyl ether 5000 tons / year, triethyl phosphite 10,000 tons / year, triphenyl phosphite 5000 tons / year, three phosphoric acid ethyl butoxy 2000 tons / year.

主要产品有：三氯化磷30万吨/年、三氯氧磷10万吨/年、五氯化磷5万吨/年、三氯硫磷1万吨/年、氯甲基甲醚5000吨/年、磷酸三乙酯10000吨/年、磷酸三苯酯5000吨/年、磷酸三丁氧基乙酯2000吨/年。

The degree of butyryl substitution of CAB increased and the degree of acetyl substitution of CAB decreased as the butyryl mol content in the reaction system increased.

制备得到的纤维素醋酸丁酸酯的丁酯取代度最高可达2.53，乙酯取代度最高可达2.98。

The models of auricular edema in mice by dimethyl benzene and increased permeability of celiac blood capillary by acetic acid were studied,the results showed that the petroleum ether and acetic ester fraction of fermentation product of Calvatia gigantea could inhibit ear edema;acetic ester and n-Butanol fraction of fermentation product could reduce the permeability of celiac blood capillary by acetic acid.

大秃马勃Calvatia gigantea发酵液的石油醚、乙酸乙酯和正丁醇提取物进行二甲苯诱导小鼠耳廓急性炎症和醋酸所致小鼠腹腔毛细血管通透性实验，结果表明大秃马勃Calvatia gigantea发酵液石油醚提取物处理组、乙酸乙酯提取物处理组对二甲苯诱导小鼠耳肿胀具有明显的抑制作用；大秃马勃Calvatia gigantea发酵液乙酸乙酯提取物处理组、正丁醇提取物处理组对醋酸所致小鼠腹腔毛细血管通透性具有明显的抑制作用。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。