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201.
香气成分的协同作用研究进展 总被引:2,自引:0,他引:2
天然产物中香气成分繁多且结构各异,这些香气成分能客观地反映天然产物的风味特点。从嗅觉产生的机理、特征香气分子形成理论和香气物质间协同作用研究方法等方面对天然产物的香气研究进展进行阐述,即通过嗅觉受体与香气分子结合,激活并传导到大脑皮层,最终完成香气感知,解释了嗅觉产生过程;从分子振动理论和识别理论角度,解释了天然产物特征香气形成原因;从阈值法、S型曲线法、OAV法、σ-τ图法等宏观层面,钙离子成像法和细胞电生理等微观层面的两个角度,解释了香气物质间的相互协同作用方法,并总结了存在的问题,对未来研究方向进行展望。 相似文献
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High‐Level Incorporation of Silver in Gold Nanoclusters: Fluorescence Redshift upon Interaction with Hydrogen Peroxide and Fluorescence Enhancement with Herbicide
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Dr. Guijian Guan Dr. Yongqing Cai Dr. Shuhua Liu Dr. Haidong Yu Dr. Shiqiang Bai Dr. Yuan Cheng Dr. Tao Tang Dr. M. S. Bharathi Prof. Yong‐Wei Zhang Prof. Ming‐Yong Han 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(5):1675-1681
High‐level incorporation of Ag in Au nanoclusters (NCs) is conveniently achieved by controlling the concentration of Ag+ in the synthesis of bovine serum albumin (BSA)‐protected Au NCs, and the resulting structure is determined to be bimetallic Ag28Au10‐BSA NCs through a series of characterizations including energy‐dispersive X‐ray spectroscopy, mass spectroscopy, and X‐ray photoelectron spectroscopy, together with density functional theory simulations. Interestingly, the Ag28Au10 NCs exhibit a significant fluorescence redshift rather than quenching upon interaction with hydrogen peroxide, providing a new approach to the detection of hydrogen peroxide through direct comparison of their fluorescence peaks. Furthermore, the Ag28Au10 NCs are also used for the sensitive and selective detection of herbicide through fluorescence enhancement. The detection limit for herbicide (0.1 nm ) is far below the health value established by the U.S. Environmental Protection Agency; such sensitive detection was not achieved by using AuAg NCs with low‐level incorporation of Ag or by using the individual metal NCs. 相似文献
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Benzoyl peroxide has been used as a mild and efficient reagent for the preparation of benzoyl ester of oxime in moderate to good yields. 相似文献
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Considering the previous study dealing with thermodynamic and kinetic phenomena (nucleation and crystal growth) during the uranium peroxide precipitation, this work focuses on the agglomeration mechanism. It provides the results obtained from the experiments carried out in a MSMPR reactor operating at steady state. The influence of the operating parameters on the uranium peroxide agglomerates was studied in order to identify the agglomeration kernel. The method is based on the resolution of the population balance equation using the method of moments and the experimental particle size distributions. The results lead to a size-independent kernel directly proportional to the crystal growth rate. Under the stirring conditions studied, the agglomeration appears to be significantly reduced by mixing which results in a kernel inversely proportional to the average shear rate. The agglomeration kinetic law obtained in this study will be used for the process modelling in a further study. 相似文献
209.
Catalytic activity of nickel(II), copper(II) and oxovanadium(II)‐dihydroindolone complexes towards homogeneous oxidation reactions
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Mohamed Shaker S. Adam 《应用有机金属化学》2018,32(4)
Three novel paramagnetic metal complexes (MH2ID) of Ni2+, Cu2+ and VO2+ ions with 3‐hydroxy‐3,3’‐biindoline‐2,2’‐dione (dihydroindolone, H4ID) were synthesized and characterized by different spectroscopic methods. The ligand (H4ID) was synthesized via homocoupling reaction of isatin in presence of phenylalanine in methanol. Complexation of low valent Ni2+, Cu2+ ions and high valent VO2+ ions with H4ID carried out in 1: 2 molar ratios. A comparison in the catalytic potential of paramagnetic complexes of low and high valent metal ion was explored in the oxidation processes of cis‐cyclooctene, benzyl alcohol and thiophene by an aqueous H2O2, as a green terminal oxidant, in the presence and absence of acetonitrile, as an organic solvent, at 85 °C. NiH2ID, CuH2ID and VOH2ID show good catalytic activity, i.e. good chemo‐ and regioselectivity. VOH2ID has the highest catalytic potential compared to both Ni2+‐ and Cu2+‐species in the same homogenous aerobic atmosphere. Catalytic oxidation of other alkenes and alcohols was also studied using NiH2ID, CuH2ID or VOH2ID as a pre‐catalyst by an aqueous H2O2. A mechanistic pathway for those oxidation processes was proposed. 相似文献
210.
《应用有机金属化学》2017,31(7)
A heterogeneous catalyst (FeSi/Ag/VO) based on silver and vanadyl as active sites and mesoporous silica‐coated nanospheres of magnetite (Fe3O4@m‐SiO2) as support was successfully prepared by deposition of Ag nanoparticles and the covalent grafting of vanadyl(IV) acetylacetonate on Fe3O4@m‐SiO2. The catalyst exhibited excellent activity for the oxidation of alkanes, benzene and alkylaromatics using green oxidant H2O2 and oxalic acid in acetonitrile at 60 °C. 相似文献