酸式酯

Low molecular weight mannuronic acid, guluronic acid and κ carrageenan were prepared from algin and carrageenan by the acid hydrolysis method, and their weight average molecular weights and the distribution widths of molecular weight were determined by high performance gel permeation chromatography respectively.

本文以褐藻胶和κ-卡拉胶为原料通过酸水解分别获得了低聚的甘露糖醛酸、古罗糖醛酸和低聚κ-卡拉胶，并采用 HPGPC法测定了这 3种低聚糖的重均分子量。在此基础上再经硫酸酯化和成盐修饰制备了各自的硫酸酯碱式铝盐。

ABSTRACT Immobilized penicillin acylase (from E.coli) was used to catalyze 7 phenylacetamido 3 E propenyl cephalosporanic acid hydrolyzation into 7 amino 3 E propenyl cephalosporanic acid. Then, trans APRA was acylated with hydroxyethyl ester of 4 hydroxy D phenylglycine to obtain trans cefprozil.

以7 苯乙酰氨基 3 E 丙烯基 3 头孢菌素 4 羧酸为原料，在青霉素酰化酶作用下，首先酶法水解得到3 E 丙烯基 3 头孢菌素 4 羧酸，过滤固相酶，滤液调pH分离得到反式APRA固体；在青霉素酰化酶作用下，反式APRA再与对羟基苯甘氨酸乙二醇酯缩合，得到反式头孢丙烯；酶法合成所得的产品与进口反式头孢丙烯对照品一致。

Calcium carbonate and soluble glass and so on were confected as alkaline antifouling agent. The Infrared Spectrometry results showed that 2275-2250 cm~(-1) diagnostic absorb wave crest in part A and 3390-3200 cm~(-1) in part B and 1730 cm~(-1) in coating film strongly proved polymers reacted just as the reacting mechanism, that means polysiloxane which offer low-surface-energy property linked Polyurethane system by —OH groups reacting with —NCO groups. Relative molar mass of part A and part B was determined by Gel Permeation Chromatography and the results were appropriate. Surface-energy was determined and results were between 33.6-47.17 mN/m and it increased when alkaline antifouling agent was put into the coating. Alkaline antifouling agent was releasing steadily when the coating film was dipped in seawater. As time gone, the pH value of seawater was increasing. Solubility parameter and results showed that there was no corrasive phenomenon between the polyethylene strand and the coating.

红外光谱分析结果表明，出现在A组分中的2275～2250cm~(-1)处的异氰酸酯特征吸收峰、B组分中的3390～3200cm~(-1)处硅羟基的特征吸收峰及出现在固化后涂膜中的1730cm~(-1)处氨基甲酸酯基团的特征吸收峰证明了涂料成膜物质交联固化符合本文的设计要求，即赋予涂膜低表面能特性的有机硅组分通过—OH基团与—NCO基团的反应已经链接到聚氨酯体系中；凝胶渗透色谱结果表明，成膜物质的A、B组分均为低分子量，符合预聚物的要求；涂膜表面能的测算结果表明，涂膜的表面能在33.6～47.17mN／m之间；加入碱式防污剂后涂膜的表面能略有升高；碱式防污剂的释放平稳，随着涂膜在海水中浸泡时间的增长，pH值有增加的趋势；用溶解度参数原则来评价涂料与网绳的涂装，结果表明，本试验研制的防污涂料对聚乙烯网绳无溶蚀作用。

4R,5S,6R-5,6-Bis-allyl-6-aldehyde-γ-hexanelactone I-145 was prepared from D-arabinose by six steps. Compound I-145 underwent Mukaiyama-type intramolecular aldolization to produce bicyclooctane I-147 stereospecifically.

我们以D-阿拉伯糖为起始原料，经六步反应，得到(4R，5S，6R)-5， 6-二烯丙氧基-6-醛基-γ-己酸内酯I-145，然后I-145发生分子内的Mukaiyama式aldol缩合反应，完全立体专一性地得到环化中间体I-147。

However, the molecular mechanisms underlying premature aging up 8-MOP/UVA are as yet unknown. In our studies, dermis of the non-lesion back skin of vulgar psoriatic patients who had been treated by PUVA and the cultured foetus dermic fibroblasts were selected to be observed.

本课题以PUVA治疗寻常型银屑病患者背部非皮损区真皮及培养的胎儿真皮成纤维细胞为对象，采用HE染色、Verhoeff染色、电镜、酶组织化学、免疫组织化学、原位杂交、流式细胞计数仪、三引物PCR、PCR-SSCP技术及PCR产物直接测序等技术和方法，研究了8-MOP/UVA对皮肤光老化形成的影响及芳维A酸乙酯的拮抗作用。

HBPSi to join after, HBPSi of epoxy groups can triazine ring into isocyanuric acid ester, isocyanuric acid ester and then with epoxy to form one oxazoline (see signal-1a), To reduce the stiffness of the resin network.

加入HBPSi后，HBPSi的环氧基团可使三嗪环转化为异氰脲酸酯，异氰脲酸酯进而与环氧基反应生成噁唑啉酮（oxazolidinone rings(见示意式1a)，降低了树脂网络的刚性。

Such structural complexity is further enhanced by O-acetylation, esterification, lactonization, as well as other forms of substitutions, reflecting significance of carbohydrates in cell recognition.

细胞表面上糖缀合物的糖链经常以多/寡聚体形式存在，并且结构复杂，常常大量表达唾液酸、糖醛酸、硫酸化糖基等酸性糖，并发生O-乙酰化、酯化和内酯化等修饰。

A series of 3 - aryl - 3 -( 5,5 - dimethyl - 3 - hydroxy - 2 - cyclohexene - 1 - one - 2 - yl) propanoic ester s were synthesized by reaction between aromatic aldehydes ,5,5- dimethyl -1,3-cyclohexanedione and isopropylidene malonate catalyzed by KF - Al2O3 in alcohols.

在KF-Al_2O_3催化下，将芳香醛3，5-二甲基-1，3-环己二酮及丙二酸亚异丙酯在醇中反应，一锅式合成了一系列的3-芳基-3-(5，5-二甲基-3-羟基-2-环己烯-1-酮-2-基)丙酸酯。

Objective To investigate the differentiation of NB4 and MR2 cells induced by tributyrin in combination with different doses of all-trans retinoic acid and to see if TB can induce apoptosis of NB4 and MR2 cells.

目的 研究三丁酸甘油酯与全反式维甲酸不同浓度组合对NB4及MR2细胞的诱导分化作用，并观察TB对NB4、MR2细胞是否具有促凋亡作用。

Methods: Fat extracted from food and oil sample was determined directly on the ZnSe crystal cisterna of horizon attenuation total reflection equipment with deuterated triglycine sulfate detector in the FT-IR.

食品中提取的脂肪或油脂样品直接置于红外光谱仪的水平衰减全反射部件的槽式ZnSe晶体上，氘化三甘氨酸硫酸酯检测器检测。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷