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金银花叶的抑菌活性和抗氧化性研究 总被引:1,自引:0,他引:1
采用滤纸片法和D值计算法研究了金银花叶中天然抗菌物质的体外抑菌活性,采用分光光度法测定了其抗羟自由基的氧化活性。抑菌实验结果表明,金银花叶的乙醇提取物抗菌谱较广;乙醇提取物水溶液的乙酸乙酯萃取物抑菌效果最为显著,测得其对金黄色葡萄球菌和大肠杆菌的最低抑菌浓度分别为0.38%和0.50%。抗氧化实验结果表明,金银花叶乙醇提取物具有一定的抗羟自由基氧化活性,其乙酸乙酯萃取物在1mg/mL的低浓度下就显示出了较好的效果。 相似文献
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研究了樟树和黄花蒿的乙醇、氯仿、石油醚浸提物对菜粉蝶幼虫的拒食作用、触杀作用。结果表明黄花蒿乙醇浸提物和樟树石油醚浸提物的活性较好,48 h拒食率分别为72.11%、57.86%;干物质触杀作用的LC50分别为1.232 g/L、1.275 g/L。 相似文献
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《广州化工》2016,(7)
探讨了桃树叶中黄酮的提取方法,研究了溶剂浸提温度、时间、固液比、乙醇浓度,超声波或微波辅助等对桃叶中黄酮提取效果的影响。研究结果表明:溶剂浸提中,影响因素依次为:料液比乙醇浓度浸提温度水浴时间;超声波辅助提取中则为乙醇浓度料液比浸提温度超声时间;微波提取中则又为微波时间微波功率料液比乙醇浓度。用70%乙醇作为浸提溶剂,料液比1∶25,温度控制在30℃,1次浸提40 min,桃叶黄酮提取率1.81%;采用超声波辅助提取,料液比为1∶30,浸提温度控制在50℃,提取30 min,用70%乙醇提取桃叶黄酮,提取率最高达3.98%;使用微波辅助提取时,料液比1∶30,微波功率控制在200 W,用60%乙醇提取30 s,则黄酮提取率3.92%。由此可见,纯粹用溶剂提取,提取率较低,不到2%,采用超声波或微波辅助提取,可达近4.0%。 相似文献
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以卷心菜叶为原料,研究微波法辅助提取卷心菜叶中绿原酸的工艺。以绿原酸的提取率为考查指标,考查乙醇浓度、料液比、微波温度、微波时间、微波功率、浸提温度、浸提时间、pH等因素对卷心菜叶中绿原酸提取率的影响。 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively.
There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized.
High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without
the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of
fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to
achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic
SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve
F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender
particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing,
and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing
or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually
preserves suspension stability during freezing.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago,
IL. Tied for first place in The John A. Gordon Best Paper Competition. 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria. 相似文献
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It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples. 相似文献
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Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US
In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae
and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted
in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures
(release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species
(Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species
to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were
exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of
separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles
from the southeastern region of the US. 相似文献
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Peter A. Edwards Grant Striemer Dean C. Webster 《Journal of Coatings Technology and Research》2005,2(7):517-527
Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins.
Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol.
The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and
cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on
the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to
determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model
amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate
functional group is more reactive than a glycidyl ether group.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago,
IL. 相似文献
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Dongjiang Yang Yao Xu Lei Zhang Shangru Zhai Dong Wu Yuhan Sun 《Journal of Coatings Technology and Research》2006,3(2):127-131
A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by 1H MAS NMR. For direct comparison purposes, an SiO2 coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N2 absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals. 相似文献