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甜菊糖苷是一种天然甜味刑,在酸性条件下水解为异甜菊醇。异甜菊醇具有降血压、降血糖、抗炎和抗肿瘤等生理活性。本文对异甜菊醇及其衍生物在抗炎、抗肿瘤、手性催化和分子识别方面的应用研究进行了总结。 相似文献
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分别以盐酸或氨基磺酸为催化剂水解斯替夫苷(St),研究底物质量浓度、反应温度、催化剂用量和反应时间对斯替夫苷水解的影响,着重考察了斯替夫苷的转化率、甜菊醇的产率和异甜菊醇的产率。其中,盐酸催化水解斯替夫苷的最优工艺条件为:反应温度95℃,底物质量浓度400 g/L,盐酸浓度0.04 mol/L,反应时间28 h;在该条件下,根据高效液相色谱分析计算得到斯替夫苷转化率接近100%,甜菊醇产率达83.6%,异甜菊醇产率达12.4%。氨基磺酸催化反应的工艺条件为:反应温度95℃,斯替夫苷质量浓度400 g/L,氨基磺酸浓度0.05 mol/L,反应时间31 h;在该条件下,根据高效液相色谱分析计算得到斯替夫苷转化率接近100%,甜菊醇产率达81.5%,异甜菊醇产率达11.7%。 相似文献
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异斯特维醇是由天然产物甜菊糖苷经酸解得到,其衍生物在生物活性方面的应用研究较多。本文对异斯特维醇衍生物在生物活性、催化剂、分子识别和超分子组装等领域的应用进行了综述。 相似文献
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几种炔醇的合成及缓蚀效果 总被引:1,自引:0,他引:1
采用醇钾催化法以二甲苯为溶剂 ,分别由丙酮、丁酮和甲基异丁基酮与乙炔合成了甲基丁炔醇、甲基戊炔醇和二甲基己炔醇。整个反应在常压下进行。研究了催化剂用量 ,反应温度和反应时间对三种炔醇产率的影响。最佳合成条件是 (根据炔醇种类不同 ) :n(KOH)∶n(酮 ) =1~1.4,反应时间 1~ 1.5h ,反应温度为 0℃ ,炔醇产率为 82 %~ 96 %。将炔醇和其他组分复配成缓蚀剂 ,在w(HCl) =15 %的盐酸中进行缓蚀实验。结果表明 ,甲基戊炔醇的缓蚀效率和对温度的稳定性优于其余两种炔醇。盐酸中添加质量分数 0 1%的甲基戊炔醇 ,并与其他缓蚀组分共同作用 ,在 80℃时 ,N80钢片的腐蚀速率可以降到 4 5g·m-2 ·h-1。 相似文献
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利用荧光光谱及流体动力学等方法,研究了普利沙星(PLFX)-Co(phen)32+与CT-DNA间的作用机理.荧光光谱测量结果表明:普利沙星和Co(phen)32+发生了结合作用形成了复合物;配比为2,1;向PLFX-Co(phen)32+体系中,加入CT-DNA后,复合物进一步与DNA相结合,结合常数为2.18×105L/mol.通过粘度法、熔点测定及凝胶电泳实验研究了复合物与CT-DNA的相互作用.结果表明体系与CT-DNA间主要是沟槽作用;PLFX-Co(phen)32+能够有效切割质粒DNA. 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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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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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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Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
收集了2007年7月~2008年6月世界塑料工业的相关资料,介绍了2007~2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
收集了2005年7月~2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、通用热固性树脂(酚醛、聚氨酯、不饱和树脂、环氧树脂)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。 相似文献