细叶石仙桃乙酸乙酯部位自由基清除活性研究

测定细叶石仙桃乙酸乙酯部位总黄酮含量,并测定其自由基清除活性,探究两者之间的关系。以芦丁为对照品测定细叶石仙桃乙酸乙酯部位总黄酮含量,并采用DPPH自由基和羟自由基体系评价其对自由基的清除能力。细叶石仙桃乙酸乙酯部位总黄酮含量为39. 6 mg/g,其对DPPH自由基最高可达到85. 1%,对羟自由基清除率在较低提取物浓度即达到100%。细叶石仙桃乙酸乙酯部位具有优异的自由基清除活性。     

炼油装置高温部位的腐蚀与防护

在炼油生产装置中高温部位的腐蚀是经常遇到的问题,其原因主要是高温硫化氢腐蚀的结果,对高温部位的设备及管道进行适当选材,采用合理的结构,加强工艺脱硫,以及采用化学防护措施等,从而达到防腐的目的。     

蒲桃不同提取部位总黄酮含量比较研究

研究蒲桃不同提取部位总黄酮的含量差异,为制定蒲桃的提取工艺和质量控制方法奠定基础。采用紫外分光光度法测定蒲桃醇提物不同极性溶剂萃取部位总黄酮的含量,以硝酸铝为显色剂,以芦丁为对照品,最大吸收波长为510 nm。结果表明:蒲桃不同提取部位的总黄酮在15.24~76.20μg·mL-1(r=0.9991)范围内与吸光度呈良好线性关系,总黄酮含量其乙酸乙酯部位占34.84%、三氯甲烷部位占20.36%、正丁醇部位占19.72%、水部位占17.79%和石油醚部位占7.29%。蒲桃不同提取部位总黄酮含量的比较结果:乙酸乙酯部位>三氯甲烷部位>正丁醇部位>水部位>石油醚部位,为进一步研究蒲桃的提取工艺和质量控制方法奠定基础。     

789胶的制备及应用

一、前言在局部电镀工艺中,对于需要浸入电解液但又需要禁镀的部位,必须进行很好的绝缘。对几何形状简单的禁镀部位,一般采用塑料布包扎的方法实施绝缘。对于几何形状复杂,电镀时间较长的禁镀部位,采用简单的包扎法是不能胜任绝缘的。人们往往是采用涂蜡和涂复各种绝缘胶的方法实施绝缘。涂蜡的方法工艺繁琐、耐温性差、绝缘可靠性差,因此,其应用范畴受到很大限制。涂     

稀硝酸尾气预热器的腐蚀与防护

在采用中压吸收工艺,生产浓度为55—60％的稀硝酸生产装置中,管壳式尾气预热器之管板与换热管采用焊接联接,其焊缝热影响区部位遭到严重的局部腐蚀。本文对其腐蚀机理及其防护措施做了较详尽的叙述。     

硝酸尾气预热器的腐蚀与防护

在采用中压吸收工艺,生产浓度为55—60％的硝酸装置中,管壳式尾气预热器之管板与换热管采用焊接联接,其焊缝热影响区部位遭到严重的局部腐蚀。本文对其腐蚀机理及其防护措施作了较详尽的叙述。     

鸡冠花活性成分的提取及其抑菌效果

以鸡冠花为原料，采用回流提取法提取鸡冠花不同部位活性成分，采用其琼脂平板二倍稀释法进行体外抑菌活性实验，对不同活性成分进行热处理、紫外线照射研究其稳定性，统计抑菌物质的的最低抑菌浓度以及不同条件下的稳定性。结果表明，鸡冠花二氯化碳部位有较好的抑菌效果，在紫外照射的情况下，抑菌性的稳定性较好，但不宜长时间在高温环境中。     

白花蛇舌草提取物体外抗5-LOX活性研究

研究白花蛇舌草的抗炎活性部位以及提取方法对其的影响。采用70%乙醇回流和石油醚脱色两种不同的提取方法,按照溶剂极性由低到高萃取得到石油醚、乙酸乙酯和正丁醇提取物,所得样品用比色法检测其抗5-LOX活性。最终发现脱色后的白花蛇舌草抗5-LOX活性较好,抗炎主要活性在乙酸乙酯部位,其抑制率为66.98%。脱色后白花蛇舌草的提取物可减少杂质对其抗炎活性的影响,乙酸乙酯部位可作为抗炎药物筛选部位。     

狐尾藻乙酸乙酯萃取部位总黄酮含量测定与抗氧化活性研究

目的:以浙江省采集的狐尾藻作为研究对象,将狐尾藻植物乙醇提取的浸膏用乙酸乙酯进行萃取,对所得乙酸乙酯部位进行抗氧化活性测定。为狐尾藻的开发利用提供科学依据。方法:通过比色法对狐尾藻乙酸乙酯部位总黄酮总酚酸含量进行测定,采用DPPH法、羟自由基法测定狐尾藻乙酸乙酯部位的抗氧化活性。结果:狐尾藻乙酸乙酯部位含有黄酮类化合物,且样品溶液具有较好的抗氧化活性,在一定浓度范围内,样品浓度越高,其抗氧化活性越强。结论:该研究结果表明狐尾藻中含有黄酮类化合物,且在一定范围内其抗氧化活性比Trolox强。     

基于有限元技术的仪表板综合特性评估及结构轻量化

针对乘用车仪表板的综合特性是否达标问题,首先约束仪表板有限元模型的连接点,得到其前三阶频率及阵型,以此进行模态特性评估。然后施加三倍重力加速度对其进行振动强度特性仿真分析,获取其应力水平。再在其薄弱区域加载相同的作用力对其进行抗凹特性仿真分析,得到其变形量。最后针对其某部位变形过大的问题进行局部加强,并采用第二代非劣排序遗传算法对其主要部位的厚度进行优化设计,获取其最佳的结构,优化之后其综合特性满足设计要求,同时质量减轻了14.6%,达到了综合性能与轻量化的最优化。     

无叶假木贼杀虫有效部位的研究

依次通过酸水煮沸、煤油萃取和不同酸碱度下氯仿萃取煤油层，从无叶假木贼中得到两个提取部位。田间杀虫试验证明其中一部位有良好的杀虫效果。对该杀虫有效部位进行化学成分分析．通过薄层层析和气相色谱-质谱方法，证明有效部位的主要成分是毒藜碱和羽扇豆碱。     

Trail pheromone of the antTetramorium impurum and model compounds: Structure-activity comparisons

The major component of the trail pheromone ofT. impurum is methyl 2-hydroxy-6-methylbenzoate (methyl 6-methyl salicylate). The poison reservoir of each worker contains about 1.0 ng of this substance in the venom. To ascertain the degree of specificity of the substance as pheromone and to determine any correlation between structure and biological activity, 38 synthetic analogs were tested in a bioassay. Sixteen compounds showed activity at 100 ng per artificial trail. The importance of the methyl group and methyl ester were demonstrated, while the hydroxyl group has a relatively small effect.In part presented at the Fourth Annual Meeting of the International Society of Chemical Ecology, July 13–17, 1987, Hull, England.     

Alarm substance of the marine mud snail,Nassarius obsoletus: Biological characterization and possible evolution

The gastropod snailNassarius obsoletus shows a dramatic self-burial response to the presence of crushed conspecifics. After it was shown that this burial alarm response could be reliably replicated in laboratory tests, a further characterization of the alarm substance was undertaken. Dilution experiments showed a very high response threshold resulting in a short effective radius of the substance in agreement with earlier field reports. Longevity experiments showed that the substance had lost some activity after 16 hr standing over marsh mud in sea water at room temperature; it became inactive after 24 hr. Superthreshold concentration in sea water was not necessary to keep the snails buried: Mud apparently provides an adsorption surface which can remain a stimulus source for previously unalarmed snails, and snails tend to remain buried after a short exposure to alarm substance, even when given a fresh environment. The substance is present in the snail's blood and tissues and is passively released. A potential natural predator capable of such release isCarcinus maenas, the green crab. Predator odor alone did not cause burial alarm responses. Preliminary chemical analysis indicates that the substance is water soluble, heat stable, and of high apparent molecular weight (over 100,000). A comparison with fish alarm substance and response is made in a discussion of the possible evolution of chemically triggered alarm responses. It is argued thatN. obsoletus may have developed an alarm response to an existing nonspecific substance rather than a true alarm pheromone.This paper is based in part upon a thesis submitted by D.S. to Boston University for the degree of Master of Arts.     

FT-i.r. spectroscopic analysis of coals and coal extracts

Several Canadian coals were analysed by FT-i.r. The technique is applicable to both the organic and inorganic part of the coal. The method by which the spectra can be subtracted one from the other, allows the distinguishing of one coal from another by characteristic functional groups. The high resolution of the resultant spectra clearly differentiate between the substance extracted by solvents, the unextracted coal material and the original coal itself. The technique has been used to show that the quinoline extract of bituminous coal contains an adduct in which some quinoline is chemically bound to the extracted coal substance. This adduct cannot be removed by washing the extract with HCl at a pH of 2.     

Effects of vortices on diffusion and heat transfer

The unusual phenomenon observed by D.I. Taylor and other researchers was explained. During the vortex motion of the liquid, the distributed component of the diffusing substance is concentrated only in the vortex core. The effect was explained in terms of our hypothesis that takes into account the dependence of the diffusing substance flow not only on the concentration gradients, but also on the vorticity of the liquid. The concept offers a new glimpse on natural and technical effects such as the tornado and the Ranque effect.     

Analysis of phase transformations in shock-compressed potassium chloride and <Emphasis Type="Italic">α</Emphasis>-quartz in terms of x-ray crystallography

X-ray diffraction patterns of shock-compressed samples of potassium chloride and α-quartz were analyzed in order to estimate the physical state of the substance in the phase coexistence region and the effect of the relaxation process on the location of experimental Hugoniot points in this region. The experimental results are consistent with the interpretation that the state of a substance on the transition curve connecting the Hugoniots of the initial phase and the high-pressure phase can be represented as a state of the substance with an incomplete relaxation process. The degree of incompleteness is determined by the ratio of the residence time of the substance at the shock front to the full time of the relaxation process.     

聚苯乙烯纳米标准物质制备研究

随着纳米技术的发展,纳米标准物质的应用需求增加,制备技术取得了长足的发展.对聚苯乙烯纳米标准物质的制备方法进行了综述,并重点讨论了各种不同制备方法中影响粒径和粒径分布因素.     

臭氧消解技术在水样重金属测定中的应用

阳极溶出伏安法是测定水样中痕量重金属的常用方法,但水样中的有机胺等干扰物严重影响该方法的定性和定量。采用臭氧消解技术对加入模拟干扰物的水样和排污口水样进行了消解,并对铜、锌、铅、镉等元素进行了测定。结果表明,该方法对干扰物有较好的去除效果,方法的准确度和精密度较好,并且操作简便、高效,易于实现自动化。     

Snf 907-76发酵液杀线虫活性测定及活性物质分离纯化

球孢白僵菌（Bwauveria bassiana）摇瓶发酵后,产生高杀线虫活性物质。通过活体检测方法,分别测定了不同稀释或浓缩倍数、不同处理时间对线虫死亡率的影响,并测定了发酵液的杀线虫谱。活性物通过无水乙醇沉淀,有机溶剂萃取,活性炭柱、732型阳离子交换树脂柱及硅胶柱层析后,经硅胶薄层层析、紫外-可见光检测和高效液相色谱检测,其纯度达97.38%,可用于物质进一步结构分析及性质测定。     

新生牛脑低分子提取物对神经突起生长的作用

以鸡胚背根神经节无血清培养及大鼠子鼠脑神经细胞无血清培养作为模型 ,检测以新生小牛脑为原料制备的低分子脑提取物对神经细胞突起生长的作用。结果表明 :(1)低分子脑提取物可促进鸡胚背根神经节神经突起的生长 ,加入低分子脑提取物 48h后 ,神经节周围长出突起 ,随着时间的推移 ,神经突起生长得长而密 ,相互交织在一起。 (2 )借助图像分析仪 ,以大鼠子鼠脑神经细胞神经突起平均数及神经突起平均长度为指标 ,观察到低分子脑提取物能促进神经细胞神经突起生长。低分子脑提取物经HPLC分析 ,在 2 80nm部分可分为 5个组分 ,究竟是哪一组分或哪几组分起促神经突起生长作用 ,尚需进一步研究。