乙酸乙酯

College of Veterinary Medicine, China Agricultural University, Beijing 100094, China Abstract: A method has been developed to determine residual stilbenes such as diethylstilbestrol, dienestrol and hexestrol in animal tissues using solid phase extraction and gas chromatography-mass spectrometry.

动物组织样品在碱性条件下用乙酸乙酯提取，经碳酸钠溶液液-液分配净化，再用硅胶柱固相萃取净化，洗脱液均分成两份后经氮气吹干，分别用双三甲基硅基三氟乙酰氨和七氟丁酸酐衍生，采用选择离子监测模式进行测定，外标法定量。

A GC headspace injection method for the determination of residual organic solvents such as methanol, ethanol, acetonitrile, dichloromethane, ethylacetate, 4 methyl 2 pentanone, toluene, DMF, chloroform and tetrahydrofuran in tazobactam was established.

建立了气相色谱顶空进样法测定三唑巴坦中甲醇、乙醇、乙腈、二氯甲烷、乙酸乙酯、甲基异丁基酮、甲苯、N ，N′-二甲基甲酰胺、氯仿和四氢呋喃等有机溶剂的残留量。

Alumina sols of different content were prepared by using Al3 as precusor, water as solvent, nitric acid as peptizer, ethylacetoacetate and polyvinylpyrrolidone as modified menstruum. We used dip-coating method and spin-coating method prepared of alumina films on the plane glass and used dip-coating method and rising liquid method inside the wall of the fiber.

以仲丁醇铝为前驱物、水为溶剂、硝酸为胶溶剂、同时加入乙酰乙酸乙酯和聚乙烯吡咯烷酮作为改性剂制备了不同浓度的氧化铝溶胶用提拉法和旋覆法在平板玻璃上镀膜，同时用提拉法和液面上升法在石英毛细管内壁上镀膜。

Results By using two-phase solvent systems composed of petroleum ether-ethylacetate-methanol-water (22:25:23:17) at the flow rate of 2.0 mL/min, with rotating speed of 800 r/min, and at temperature of 25℃, the yield of d1-tetrahydropalmatine and of protopine purified from the total alkaloids being 16.9% and 14.7%, with purity of 99.3% and 98.8% respectively can be reached.

结果 石油醚－乙酸乙酯－甲醇－水(22：25：23：17)为溶剂体系，流速为2.0 mL/min，仪器转速800 r/min，温度25℃，从延胡索总碱中可一步纯化得到原阿片碱和延胡索乙素，得率分别为16.9%和14.7%，纯度分别为99.3%和98.8%。

This reflected that EMP and HMP pathways and the tricarboxylic acid cycle were very important to the bioreduction.

表明糖酵解途径、磷酸戊糖途径和三羧酸循环的顺利进行对于面包酵母在有机介质中催化4-氯乙酰乙酸乙酯还原反应都是十分重要的。

Pesticides were extracted from sample with ethyl acetate in an ultrasonic bath, then determined by gas chromatography-mass spectrometry operated in negative chemical ionization mode and quantified in selective ion monitoring mode, and ethion was used as an internal standard.

蔬菜水果样品用乙酸乙酯超声提取，以乙硫磷为内标物，采用GC-NCI-MS的选择离子监测方式进行定性和定量分析。9种有机磷农药的方法检测限为0.12～1.0 μg/kg。

The experimental condition of acetylating method for determining priminary alcohol and secondary alcohol catalyzed by perchloric acid in the medium of analytically pure ethylacetate is proposed.

提出了以高氯酸为催化剂，分析纯乙酸乙酯为介质，乙酰化法测定伯、仲醇的实验条件，实现了对经典方法的改进，简化了操作程

Methods: M-acetaminphen was used as an internal standard, and alkalinized samples of plasma were extracted with ethyl acetate.

以间乙酰氨基酚为内标，血浆样品经碱化后，用乙酸乙酯提取。

Samples were saponified with 20 g/L sodium hydroxide. The sexual hormones were then extracted with dichloromethane-acetic acetate (40∶1, v/v) under acidic conditions (pH 3, adjusted with 1 mol/L HCl ). An XTerraTMRP18 column was employed and a mixture of water-methanol-acetonitrile (50∶32∶18, v/v) was used as mobile phase. The seven sexual hormones were detected at 230 nm. The average spiked recoveries for the seven sexual hormones ranged from 75.6% to 97.8% with relative standard deviations of 1.9% to 7.2%. The linear ranges of determination were from 5 to 50 mg/L with correlation coefficients of 0.9999, and the limits of detection were from 3.7 to 12 ng.

先在试样中加入20 g/L氢氧化钠溶液与油脂进行皂化反应，然后用二氯甲烷-乙酸乙酯(体积比为40∶1)混合液在酸性条件下(pH 3)萃取，选择XTerraTMRP18色谱柱，以水-甲醇-乙腈(体积比为50∶32∶18)混合液为流动相，在波长230 nm处检测。7种性激素分离良好并排除了样品中杂质峰的干扰，低、高浓度平均回收率范围为75.6%~97.8%；相对标准偏差为1.9%~7.2%；检出限为3.7~12 ng。

Four substances including 2-methyl ethyl acetoacetate and barley straw extract distilled from bulrush as well as cetyl trimethyl ammonium bromide and isothiazo lintone were used for the comparison experiment in inhibiting the growth of Microcystis aeruginosa in various phases. Result showed that inputting chemicals in the lag phase has better effect than in the log phase, and adding in lag phase can effectively inhibit the algae growth. Although feeding allelopathic substance at log phase can lead to certain restraining effect, it cannot result in the effective inhibition of algae growth, which can be well achieved by feeding CTAB and isothiazo lintone below 10mgl/L during log phase.

研究用从芦苇中提取的2-甲基乙酰乙酸乙酯和大麦秸浸出液两种化感物质以及十六烷基溴化钱和异噻唑啉酮等四种药剂对不同生长期的铜绿微囊藻进行了对比抑制试验，结果显示在铜绿微囊藻生长的迟缓期投加试验药剂效果比在对数期投加效果都好，在迟缓期投加四种药剂，都有很好的抑藻效果；在铜绿微囊藻生长的对数期投加化感物质，虽然有一定的抑藻率，但效果较差，而在藻对数期投加10mg/L以下的CTAB和异噻唑啉酮能达到很好的水华抑制效果。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。