乙酸

It,s allelchemicals were isolated through extraction, thin-layer chromatography, and column chromatograpathy. After the white clover was infused in ethanol and evaporation, the leavings was dissolved by water. The aqueous extract was extracted by petroleum,chloroform, ethyl acetate and n-Butanol successively, and the bioassay showed that the chloroform phase has obvious inhibitory effect, the inhibitory rate was 44.32%,88.08% on Abutilon theophrasti M., seedling length and root length, 82.08%,92.16% on Echinochloa crusgalli L., seedling length and root length, and the Amaranthus retroflexux L., germination rate is 0, the secondly was ethyl acetate phase.

运用萃取、薄层层析、柱层析等方法对白三叶草地上部分的化感物质进行初步分离，结果表明，白三叶草经乙醇浸提旋转蒸发后用蒸馏水溶解，依次用石油醚、氯仿、乙酸乙酯、正丁醇萃取，生物测定表明氯仿组分对杂草的抑制作用最强，对苘麻芽长和根长抑制率分别为44.32%、88.08%，对稗草芽长和根长的抑制率分别为82.08%、92.16%，反枝苋的发芽率为0；其次是乙酸乙酯相。

A brief account of technique conditions of several main technique routes for synthesizing glycollic acid and existing main problems in it are given.

概述了羟基乙酸几种主要工业合成方法的工艺条件及存在的主要问题，即氯乙酸水解法、氰化法、甲醛羰基化法和一氯乙酸钾水解法。

Compared with other antiseptic,SDA can make food have non-harm,fresh,good taste,long stire,low price etc merits.

称双乙酸钠与其它防腐剂相比，经添加SDA的食品，具有无毒、鲜美、口味纯正、储存期长、价格地、低等优点，特别是既没有山梨酸钾的异味，又没有丙酸钙的涩味，更没有苯甲酸钠的怪味，又因为双乙酸钠为钠盐，不会影响食品的绵软。1/3-1/2量的双乙酸钠抑菌效果与丙酸钙相当，与等量的梨酸钾防腐效果相当，但价格极为低廉。

The experimental results show that in the presence of acetic anhydride, the L-tyrosine can be completely racemized and converted into DL-tyrosine both in NaOH aqueous solution and in acetic acid solvent, and moreover, in the presence of acetic anhydride

今讨论了在碱性水溶液中，L-酪氨酸、乙酸酐和NaOH三者摩尔比例对消旋过程的影响和在纯乙酸溶剂中，乙酸用量和L-酪氨酸与乙酸酐的摩尔比例与消旋温度对消旋过程的影响。结果表明在乙酸酐的作用下，L-酪氨酸在纯乙酸溶剂中的消旋具有消旋速度快，DL-酪氨酸收率高的优点。

The paper involved two parts: Part 1: A two-chambered microbial fuel cell was constructed with high-concentration sodium acetate as fuel in the anode. The influence of different electron acceptors in the cathode, external resistance value, pH value and concentration of sodium acetate on electricity generation in MFC was investigated. The result showed that the maximum power density of 294.72 mW/m2 and the coulombic efficiency of 25.87% was achieved at sodium acetate concentration of 6.46 g/L, pH 7.0, external resistance 500Ωin the anode and when using potassium permanganate as electron acceptor in the cathode.

全文分为两个部分：第一部分：以乙酸钠为阳极原料构建双室微生物燃料电池，研究不同阴极受体、外接电阻、乙酸钠浓度和pH等因素对电池产电性能的影响，研究结果表明：在500mL的阴阳极反应体系中，选用乙酸钠作为阳极底物，质量浓度为6.46 g/L， pH 7.0，接入500Ω外电阻，阴极电子受体选择高锰酸钾的情况下，微生物燃料电池产电性能最好，最大电功率密度达到294.72 mW/m2，库伦效率能达到25.87%。

The influence of reflux rate at the top of tower, light density, ratio of feed and discharge, content of water and ferrous iron in the raw materials were investigated. The output of column was also inspected.

大量二氯乙酸的生成不仅增加了原料消耗，提高了成本，而且由于后续分离困难，使氯乙酸产品质量较低，加之二氯乙酸的用途很少，造成资金和设备的巨大浪费。

Glycidyl benzoate,glycidyl propionate,glycidyl acetate were obtained respectly through a phase-transfer catalytic methodology using sodium benzoate, sodium propionate, sodium acetate and epichlorohydrin as raw materials, and pure products were obtained though vaccum distillation.β-cyclodextrin and glycidyl benzoate, glycidyl propionate, glycidyl acetate, reacted in organic solvent and goal product were

先以苯甲酸钠、乙酸钠、丙酸钠和环氧氯丙烷为原料在相转移催化剂的作用下分别合成了苯甲酸缩水甘油酯、乙酸缩水甘油酯和丙酸缩水酯，经过减压蒸馏，得到相应的纯品；β-环糊精和苯甲酸缩水甘油酯、乙酸缩水甘油酯、丙酸缩水甘油酯在有机溶剂中反应，经过硅胶色谱柱分离，得到了相应的产品，产品经过TLC、IR、1H NMR、MS表征，并研究了温度、反应时间、催化剂等几个因素对反应工艺的影响，结果表明温度和催化剂对反应的快慢有较大影响。

The effect factors on glycolic acid ratio were studied(reaction temperature,reaction time,and the ratio of catalyst to choloroacetic acid).

以氯乙酸和氢氧化钠为主要原料，碘化钠为催化剂碱性水解法合成羟基乙酸，并采用单因素法对影响因素进行了研究，得到最优化条件：反应温度90℃，反应时间8 h，催化剂NaI用量为氯乙酸质量的0.8%。

At first, the broth was acidified, then centrifuged to get mycelia, which was heated and powdered; finally we use acetic ether to soak the powder. After that, the phase of acetic ether was washed using the solution of ammonium sulfate and the solution of ethanedioic acid, then concentrated to gain pulps. It was crystallized at 4℃.The coarse crystals was decolorized by activated carbons, the pure needle crystal of lovastatin was obtained.

发酵液经酸化处理后，离心得到菌体，烘干后过筛得到菌粉；用乙酸乙酯浸泡，乙酸乙酯相需用(NH_4)_2SO_4溶液和草酸溶液洗涤两次；乙酸乙酯相经薄膜浓缩得到浆状物，于4℃结晶，得到粗晶体；再经粉末活性炭脱色和重结晶后得白色针状结晶，为lovastatin的纯品。

Mascagni were held into a solution containing calcium, ethylene glycol bis-amino tetmacetate and water, respectively. The effects of calcium were studied by measuring the ornamental quality of cut flowers and the physiological characteristics such as calmodulin, abscisic acid, gibberellins, zeatin, endogenous calcium, malondialdehyde and soluble sugar in florets.

以唐菖蒲红色品种'马加烈'切花为材料，瓶插在含有乙酸钙或钙离子专一性螯合剂乙二醇二乙醚二胺四乙酸的溶液中，分析乙酸钙对切花观赏品质的影响以及第1和第3朵小花内钙调素、脱落酸、赤霉素、玉米素、Ca(上标 2+)、丙二醛和可溶性糖含量的变化。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。