查询词典 anhydrides

The electrical insulation properties of epoxy resins cured with alicyclic anhydrides of different chemical structures were similar.

不同化学结构脂环酸酐固化后的环氧树脂电气绝缘性能相近。

Moreover, we found that N-heterocyclic carbene could served as an efficient and novel catalyst for the reactions of aziridines with silylated nucleophiles or acid anhydrides.

随后，我们发现氮杂环卡宾也可以作为一种有机小分子催化剂，分别催化各类硅试剂或酸酐对氮杂环丙烷化合物的开环。

The present invention relates to a coating composition comprising; A at least one polyester oligomer prepared from reactants comprising a 20 60 wt.% of at least one polyol, b 5 30 wt.% of at least one polycarboxylic acid selected from the group of cyclic polycarboxylic acids, the esters or the anhydrides thereof, wherein the carboxyl groups are separated by 3 carbon atoms or less, and from the group of alpha , beta -saturated acyclic polycarboxylic acids, the esters or the anhydrides thereof, and c 20 60 wt % of at least one monocarboxylic acid, the sum of the wt.% indicated for the reactants,, and always being 100 wt.%, and the oligomer being a low-viscosity oligomer having a weight average molecular weight Mw of less than 5,000, and a hydroxyl number in the range of about 200 to about 400 mg KOH/g oligomer, and B at least one polyisocyanate.

本发明涉及一种包含如下组分的涂料组合物：A至少一种由包含如下成分的反应物制备的聚酯低聚物：a20-60wt％至少一种多元醇，b5-30wt％至少一种选自其中羧基被3个或更少碳原子隔开的环状多元羧酸、其酯或酸酐以及选自α，β-饱和的无环多元羧酸、其酯或酸酐的多元羧酸，以及c20-60wt％至少一种一元羧酸，其中反应物、和的wt％之和总是为100wt％，所述低聚物是重均分子量Mw低于5000且羟基值为约200-约400mg KOH/g低聚物的低粘度低聚物，以及B至少一种多异氰酸酯。

Purple acid phosphatases catalyze the hydrolysis of a wide range of natural and synthetic orthophosphate esters and anhydrides including ATP, pyrophosphate and phosphotyrosyl proteins.

与其他磷酸酶不同，紫色酸性磷酸酶中含有Fe-M双金属原子中心而使该酶具有天然的紫色或粉色，它也因此受到科学家们的广泛重视。

Esterification process of a reversible step wereresolved as two irreversible steps,then chemical decomposition of wood components weredecreased in liquid acid catalyst.Experiments showed that crosslinking catalysts took catalysisrole on two process in the esterification,(1)five cyclic anhydrides formed by dehydration ofpolycarboxylic acids,(2)esters occurred by substitution between five cyclic anhydrides andwood.

实验中的反应过程使一般的酯化一步可逆反应，分解为两步不可逆反应，减少了液相酸催化过程的木材组分化学降解；交联反应催化剂对于多元羧酸类化合物与木材组分的酯化反应具有两个过程的催化作用：(1)多元羧酸脱水形成五元环酸酐中间体；(2)木材与五元酸酐中间体亲核取代反应形成酯。

Therefore esterification crosslinked reactionbetween polyearboxylic acid and wood can be quantitatively determined.According toexperiment results of stereoscopic configuration choices by crosslinking agents,crosslinkingreaction between model of reaction intermediate and wood,and the intermediate characteristic incrosslinking reaction,crosslinking reaction intermediate was proofed.We can infercrosslinking reactions between polycarboxylicacid and wood want through a mechanism of twosteps reaction process,the first cyclic anhydrides were formed as intermediates by dehydratingbetween hydroxyls in polycarboxylic acids,second esters were occurred by substitution reactionbetween wood hydroxyls and cyclic anhydrides.

从而可全面定量表征木材与多元羧酸类化合物的酯化交联反应；依据交联剂立体构型选择性、反应中间体模型物与木材的交联反应和交联反应中间体的波谱特征实验结果，证实了交联反应中间体，因此可以推测：多元羧酸类化合物与木材化学组分的交联反应是经历两步反应的机理，首先多元羧酸中相邻羧基的羟基之间脱水形成五元环酸酐中间体，然后木材的羟基与酸酐发生亲核取代反应形成酯。

Benzyl acetate was synthesized with dibenzyl ether and carboxylic anhydrides as raw material and solid super acid SO 2-_4/TiO_2 as catalyst.

以固体超强酸SO2 -4/TiO2 为催化剂，二苄醚和乙酸酐为原料合成乙酸苄酯，并考察了影响反应的主要因素。

The nonionic surfactant is selected from the group consisting of a polymeric ether, a mixture of laurate esters of sorbitol and sorbital anhydrides condensed with ethylene oxide; and mixtures thereof.

所述非离子型表面活性剂选自聚合醚；与环氧乙烷缩合的山梨醇月桂基酯和山梨醇酐的混合物；它们的混合物。

The invention relates to condensation products comprised of cyclic carboxylic acid anhydrides of dicarboxylic acids, tricarboxylic acid anhydrides or tetracarboxylic acid anhydrides and difunctional polyamines, especially polyoxyalkylene amines.

本发明涉及由二元羧酸的环状羧酸酐、三羧酸酐或四羧酸酐和二官能化多胺，特别是聚氧化烯胺制备的缩合产物。

Dicyclopentadiene dioxide was hardly cured by amines or acid anhydrides alone, but can be well cured by acid anhydrides mixed with alcohols.

二氧化双环戊二烯难于被胺或单独的酸酐所固化，但能很好的被酸酐与醇所固化。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。