查询词典 acetacetic ester

The synthetic route starts from penicillin G, peroxyacetic acid(8.5%) as Oxidizing Agent to get penicillin G sulfoxide; esterifided with p-nitrobenzyl bromine to synthesize penicillin G sulfoxide ester; we synthesize 3-exomethylenecepham sulfoxide ester with phthalimide potassium and 4A molecular sieve as acid scavenger to open the ring, SnCl_4 as catalyzation to close the ring. The yield is over 60%.

本研究采用的合成路线为：以青霉素G钾盐为原料，选用工业过氧化氢制备的过氧乙酸(22.3%)稀释至8.5%为氧化剂，氧化得青霉素亚砜；采用对硝基溴苄为酯化试剂，制备青霉素亚砜酯；以NCP(N-氯代邻苯二甲酰亚胺)为开环试剂，酞酰亚胺钾和4A型分子筛为酸清除剂，顺利开环；再经无水SnCl_4催化闭环得3-环外亚甲基头孢亚砜酯，最终产率在60%以上。

The ester groups of the solid polyglycerol ester particles comprise long chain (C16-C24) fatty acid radicals, with at least about 40 % of the long chain fatty acid radicals being saturated and having at least 18 carbon atoms.

这种固体聚甘油酯颗粒的酯基含有长链(C 16 ―C 24 )脂肪酸基，至少约40％的长链脂肪酸基是饱和的并且含有至少18个碳原子。

Said invented technical scheme is characterized by that it uses one kind of several kinds of five-and/or four-carbon alcohol to break the wall of wet-dried cell thallus in which the polyhydroxy fatty acid ester is self formed and extract the polyhydroxy fatty acid ester.

本发明的技术方案是用五和/或四碳醇中的一种或几种自形成聚羟基脂肪酸酯的湿/干细胞菌体破壁提取聚羟基脂肪酸酯。

Monomer which is used to synthesize polypropylene ester, mechanism of polymerization, a formula and technique parameters of synthesizing propenoic acid ester polymer are studied. An emulsifying stabilizer with good properties is synthesized.

本文研究了合成聚丙烯酸酯类物质的单体、聚合反应的机理、合成丙烯酸酯类聚合物的配方以及工艺参数，合成了具有良好性能的乳化稳定剂。

A salt or ester of benzoic acid .A salt or an ester of propionic acid .

兴奋剂一种粉末状的兴奋剂，通常是氨基丙苯

Aging mechanism of wood-plastic composite was: light and heat break down the long molecular chains of wood flour and plastic; the free radicals reacted with the oxygen, which generated carbonyl groups, hydroperoxides and so on; the free radicals also had cross linking reaction, which generated alkoxy; Water destroyed the interface of wood flour and plastic, hydrolyzed ester additives, extracted the small molecule additives and degradation products; Microorganism degraded cellulose, semicellulose, lignin and ester additives; degradation product from different component accelerated the aging, which could be exampled by the fact that HCl from degradation of PVC accelerated the hydrolyzation of cellulose and semicellulose.

木塑复合材料的老化机理为：光和热引发木塑复合材料中木质组分和塑料组分大分子链断裂，产生的自由基与氧气作用，发生链支化反应生成羰基、氢过氧化物等，发生交联反应生成烷氧基等；水分破坏木-塑界面、水解酯类添加剂、抽提小分子添加剂和降解产物；微生物分解纤维素、半纤维素、木素和酯类添加剂；木塑复合材料中各组分的降解产物相互促进老化，PVC降解产生的HCl溶于水，促进了纤维素和半纤维素的水解。

The structure of the product was characterized by IR and 1H NMR.It indicated that the double bonds in ester were sulphonated and then converted into the corresponding saturated hydrocarbon ester sulphonate after hydrolysis.

对产物用红外光谱和核磁共振 1H谱进行的结构分析结果显示，油酯的不饱和双键发生了磺化反应，生成了饱和的羟基磺酸盐。

In order to obtain versatile ulitity of host molecules, three new chiral calix [4] crown ethers containing aza, thio atoms bearing two chiral sites provided by -cysteine ester were synthesized by the condensation of calix [4] arene diacid dichloride with oligoethylene glycol bridged bis-amino acid methyl ester. All new compounds were characterized by NMR, MS and elemental analysis.

以-半胱氨酸为手性源，利用多甘醇二氯醚在碱性条件下对半胱氨酸巯基进行烷基化反应，成功地合成了多甘醇醚链桥联的半胱氨酸衍生物，醚化反应后，在高度稀释条件下与对叔丁基杯[4]芳烃二乙酰氯进行双功能基缩合反应成功地合成了新型的手性杯[4]含氮、硫杂冠醚，并利用〓H NMR、MS等谱图手段对其结构进行了表征。

In this article, three representative oil and fat resourse (edible raw oil, unedible linseed oil and waste oil and fat) were used to study the fatty acid methyl ester preparation technology, and the products from different technologies were compared and analysed. For plant oil, ester exchange process was performed immediately after simple decolorating and alkali refining pretreatment.

对于植物油脂，采用简单的脱色、碱炼预处理后，直接进行酯交换的工艺；对于废油脂，由于其成分变质较严重，预处理也显得相对复杂，采用了先预酯化再酯交换的工艺和先皂化酸化后再酯化的两种工艺。

Taking into account the fact that there is synergistic combination of the mixture stabilizer of the carboxylic ester rare earth salt and organotin mercaptide in thermal stabilization of PVC, we consider it more practial to replace partically the organotin mercaptide by the carboxylic ester rare earth salt.

特别是部分替代有机硫醇锡可发挥它们之间的协同效应，更具有实用性。

You can do some assertiveness training.

你可以进行一些自信训练。

We were well on the path to making a rear-wheel-drive global platform," says Mays."

我们正致力于建立一个后轮驱动的平台，"Mays这样说道。"