搜索结果: 16-30 共查到“知识库 物理有机化学”相关记录41条 . 查询时间(1.39 秒)
Exogenous chemical substances in bird perception: a review
anting food navigation olfactory
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2015/3/17
The perception of exogenous chemical substances, olfactory navigation and the use of the olfactory
sense by birds to search for food are reviewed. Many results suggest that the olfactory sense is on...
在青霉素上立体选择引入6α-甲(烷)氧基的新方法
青霉素 甲氧基 甲氧基 立体选择性 内酰胺 加成反应 头孢霉素 烷氧化反应
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2007/12/25
摘要 本文报导了在青霉素上立体选择引入6α-甲(烷)氧基的新方法. 苄青雷素钾盐经酯化, 亚硝化, 重氮化, 还原而制得的6-腙青雷素与芳醛在对甲苯磺酸(PTS)的催化下, 以低级醇为溶剂, 在室温反应1-2h, 即于生成连氮侧链的同时, 将相应的烷氧基引入到6α位上, 得6α-烷氧基-6β-取代腙青霉素.
一些氢化茚酮和氢化萘酮物的环氧立体构型
三乙胺 P Ｘ射线衍射分析 乙酸乙酯 甾族化合物 萘酮 P 单晶 环氧化物 茚 P 构型 β双酮类
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2007/12/25
摘要 在不同浓度的三乙胺乙酸乙酯溶液中2-甲基环戊-1,3-二酮与氯代甲基乙烯酮(1b)反应可分别得三酮、α-氯代醇或环氧双酮. α-氯代醇经X射线单晶衍射分析结果推断出环氧双酮的环氧是β构型, 其异构体为α, 用相似的方法制得的同系环氧物也经X射线单晶衍射分析, 结果表明其环氧为β构型.
氧化苯乙烯和氧化二苯乙烯的区域选择性和立体选择性开环
钠化合物 钴化合物 氯化物 选择性 区域 开环反应 立体选择性 环氧化物 硼烷类 苯乙烯 P 还原剂 二苯代乙烯 P
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2007/12/24
摘要 本文报道NaBH4-CoCl2可使氧化苯乙烯类化合物发生区域选择性开环,主要生成β-苯乙醇生物对于氧化二苯乙烯类化合物,由于受到苯环的空间阻碍,使其开环能力减弱,如反式氧化二苯乙烯比顺式异构体更难于开环.
物理有机化学的现状和在我国的进展
进展 物理有机化学
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2007/12/24
摘要 本文评述了当前物理直机化学各个主要领域的研究工作, 指出物有机化学是甚为重要的基础学科, 数十年来在深度和广度两方面皆有很大发展. 回顾了我国第一届和第二届物理有机讨会情况, 扼要地介绍了物理有机化学在我国的主要进展.
含氟环形硅氧烷的立体异构和稳定性
稳定性 质谱法 结构分析 环硅氧烷 有机氟化合物 立体异构 熔点 氟19核磁共振谱法
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2007/12/22
摘要 文献曾报道, 1,3,5-三(3,3,3-三氟丙基)-1,3,5-三甲基环三硅氧烷(简称D^F~3)有两种立体异构体, 即顺式和反式。1,3,5,7-四(3,3,3-三氟丙基)-1,3,5,7-四硅氧烷(简称D^F~4)有四种异构体。但未报道其结构特点。本文试图进一步探讨D^F~3和D^F~4的立体异构体的结构和稳定性。
超分子体系中轴－轮状D.D.主体分子的立体异构现象
包结物 立体异构 四苯基己二炔二醇 异补骨脂素 茴香醚 Ｘ射线衍射分析
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2007/12/21
摘要 组装了轴一轮状主体分子1,1,6,6-四基乙－2,4－二炔-1,6二醇(1)与天然主物异补骨脂素(2)。茴香醚(3)形成的两种超分子异构体的包结物晶体，它们的主客体分子摩尔比分别为1：2和2：1单晶X射线衍射分析了游离主体分子以及超分子包结物晶体的结构，结果表明在主客体分子摩尔比1：2的晶体中，主体分子与异补骨脂素形成氢键，主体分子采取对位交叉式构象；在主客体分子摩尔比为2：1的晶体中，主体...
摘要 本文报道采用光学纯的3R-奎宁环醇与环氧化合物作用, 得到了其中两个纯的光学异构体3R-1和3R-2, 药理实验结果表明, 它们对大鼠大脑M胆碱受体亲合力差异显著, 为了确定它们的立体结构与生物活性间的关系, 本文采用NOE差谱和二维核磁共振等技术作了研究。
Preparation and Characterization of Ordered TiO2 Photocatalysts: Films and Mesoporous Structures
Preparation Characterization Ordered TiO2 Photocatalysts Mesoporous Structures
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2010/4/16
Two different ordered TiO2 structures were prepared as sol-gel films coated on glass and as mesoporous structures in order to study the effect, in 2-D or in 3-D, of bulk size on photocatalytic activit...
Kinetics of Synthesis of Isobutyl Propionate over Amberlyst-15
Esterification pseudohomogeneous kinetics isobutyl propionate ion-exchange resin Amberlyst-15
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2010/4/16
The esterification of propionic acid with isobutanol in the presence of Amberlyst-15 as a catalyst was studied. Isobutyl propionate synthesized in this reaction has the fragrance of rum and is used in...
Kinetic Study of Selective CO Oxidation over Pt-Co-Ce/Al2O3 Catalyst in Hydrogen-Rich Streams
CO oxidation Pt-Co-Ce/Al2O3 catalyst kinetic study reaction mechanism
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2010/4/16
The kinetics of the selective CO oxidation was studied in a fixed-bed microreactor at atmospheric pressure over Pt-Co-Ce/Al2O3 catalyst, which was prepared using the incipient to wetness co-impregnati...
A Mechanistic Approach to Elucidate Ethanol Electro-oxidation
Ethanol electro-oxidation mechanism, fuel cell current
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2010/4/16
In order to elucidate the mechanism of ethanol oxidation, a simple cylindrical diffusion-surface reaction was developed on a platinum disk electrode. An ethanol electro-oxidation mechanism was propose...
PVC-Membrane Electrodes Based on 18-Crown-6 and Dibenzo-18-Crown-6 Ethers for Determination of Silver
Ag+ determination silver electrode PVC-membrane electrode
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2010/4/16
PVC-membrane electrodes for Ag+ based on either 18-crown-6 (I) or di-benzo-18-crown-6 ether (II) were applied for the first time. The effect of solvent mediator on the electrode performance was discus...
X-ray Diffraction Study of the Changes Induced During the Thermal Degradation of Poly (Methyl Methacrylate) and Poly (Methacryloyl Chloride)
X-raythe Changes Induced During Thermal Degradation Poly
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2010/4/20
Poly (methyl methacrylate) -- PMMA -- and poly (methacryloyl chloride) -- PMACl -- were synthesized by free radical solution polymerization. The thermal stabilities of these polymers were determined w...
The Hydrodynamic Properties of Micelles Formed by Block Copolymers of Isoprene and tert-Butylacrylate in n-Octane
Block copolymers hydrodynamic properties micellisation
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2010/4/20
The hydrodynamic properties of micelles formed by 2 block copolymers of isoprene and tert-butylacrylate in n-octane were investigated by dynamic light scattering (DLS) over a range of temperatures and...