乙酰

The purity of the 1-O-acetylbritannilactone product was 99.5%, which satisfies the need of reference substances of traditional Chinese medicines. A method of high performance liquid chromatography-evaporative light scattering detection is described for the determination of 1-O-acetylbritannilactone in Inula Britannica L.

以所制备的1-氧-乙酰大花旋覆花内酯为对照品，建立了用高效液相色谱-蒸发光散射检测器测定欧亚旋覆花中1-氧-乙酰大花旋覆花内酯含量的方法。

In order to supply basic thermodynamic data for the separation design of acetyl acetone from the isomerization reaction of isopropenyl acetate,vapor-liquid equilibrium data of isopropenyl acetate-acetyl acetone system under 101.3 kPa was measured using Ellis equilibrium still.

为了给乙酸异丙烯酯异构化生产乙酰丙酮工艺的产物分离设计提供基础热力学数据，用埃利斯平衡蒸馏器测定了101.3 kPa下乙酸异丙烯酯-乙酰丙酮体系的汽液平衡数据，结果表明，该二元体系未形成共沸物，实验数据通过了Herrington面积法的热力学一致性检验。

The results showed that levulinic acid was stable in near-critical water.

实验结果表明：近临界水中乙酰丙酸较稳定，在280℃、反应32h下，乙酰丙酸的转化率仅为7.0％。

A mechanism model to describe the degradation of wheat straw to produce levulinic acid was suggested based on the analysis of experimental data obtained in this work and others from both domestic and international laboratories.

通过对小麦秸秆降解生产乙酰丙酸实验数据的分析并参考国内外类似的研究结果，提出了生物质水解生成乙酰丙酸的水解机理模型。

The progress on chemical synthesis and biosynthesis of levulinic acid and 5-aminolevulinic acid(5-ALA) were discussed.

基于生物质资源的利用和开发，论述了乙酰丙酸的制取、5-氨基乙酰丙酸的化学合成与生物合成，阐述了其在医药、农业等方面的应用，讨论了发展趋势和亟待解决的问题。

The traditional separation and purification process of levulinic acid was consisted of solvent extraction and high vaccumn distillation, which was low in product recovery, high in energy consumption and complex in process operation.

传统的乙酰丙酸分离提取工艺以有机溶剂萃取和真空精馏为核心，乙酰丙酸的回收率低、能耗高、工艺复杂，成了制约工业化生产的主要因素。

Coat-of-mail shell, sea cradle, polyplacophore

壳聚糖，脱乙酰壳多糖，脱乙酰几丁质，聚氨基葡萄糖

Sinensis could be divided into 5 stages, includi ng t he spermospore proliferation stage, the primary spermatocyte stage, the secondar y spermatocyte stage, the spermateliosis stage and the spermiotiliosis stage.

在整个精子发生过程中，N-乙酰半乳糖复合物出现于精原细胞期，并于精母细胞期发生明显的修饰和变化，精子形成期和成熟期没有N-乙酰半乳糖复合物的表达。

The stereochemical structures of two new compounds, 5-(3-chlorophenyl)-2-furfur-aldehyde-N-4-methylphenyloxyacetylhydrazone and 5-(3-chlorophenyl)-2-furfuraldehyde-N-4-nitrophenyloxyacetylhydrazone, were determined by DPFGSE-NOE experiments performed in DMSO-d\-6 at 25 ℃ and variable-temperature ~1H NMR The ~1H chemical shifts of the compounds were completely assigned at 25 ℃ and 90

利用变温实验和DPFGSE NOE实验，确定了 5 (3 氯苯基) 2 呋喃甲醛 N 4 甲基苯氧乙酰腙和5 (3 氯苯基) 2 呋喃甲醛 N 4 硝基苯氧乙酰腙两个新化合物25 ℃时在二甲基亚砜中的空间构型，并对这两个新化合物在 25 ℃和 90 ℃时的质子的化学位移进行了全归属。

It is found that when the molar ratio of sulphoxide,pyridine and acetyl bromide is 1∶0.6∶0.4,the catalytic effect on the ring-enlargment is the best,and the yield and purity of the final product can reach 76% and 97% respectively at a pH of 1.8 in toluene under refluxing for about 3.5h.

通过正交实验可得出以下结论：当N，N′-双脲-亚砜为2.5∶1，乙酰溴-亚砜为0.4∶1，吡啶-乙酰溴为1.5∶1，回流时间为3.5h，酸化pH值为1.8时，扩环反应结果最好，总收率可达76%，纯度97%以上。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。