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排序方式: 共有533条查询结果,搜索用时 15 毫秒
81.
The effect of alkyl polyglucoside (APG) surfactant on the electrodeposition Co-Ni-Cu alloys nanoparticles has been investigated. In a typical electrodeposition experiment, it was found that as prepared Co-Ni-Cu alloys nanoparticles characteristics, such as size homogeneity, density, dispersion on the electrode substrate and the chemicals composition, depended strongly on the concentration of APG used in the reaction as well as the applied deposition potential. For the case of chemicals composition, low APG concentration (below CMC) was found to be effective for the preparation of excellent composition of the nanoalloys. Meanwhile, for the case of size homogeneity, density, and dispersion on the surface, high APG concentration (above CMC) and high deposition potential were preferred. It was also found that, at concentration above the CMC, the APG surfactant showed a metals ions deposition inhibition characteristic that caused increasing in the electrodeposition overpotential of the entire metals ions, namely cobalt, nickel and copper. As the result the copper was found to place a high percentage in the nanoalloys deposits. Owing to its simple procedure in controlling the composition and the nanoalloys growth characteristic, present approach should find a potential application in preparing Co-Ni-Cu magnetic nanoparticles for used in currently existing applications. 相似文献
82.
Dialkyl acetylenedicarboxylates react with alkyl 2‐nitroethanoates in the presence of alkyl isocyanides in a one‐pot reaction to afford the title compounds in 78–90% yield. 相似文献
83.
Issa Yavari Mohammad Anary-Abbasinejad Abdolali Alizadeh 《Monatshefte für Chemie / Chemical Monthly》2002,133(9):1221-1224
Summary. The reactive 1:1 intermediate produced in the reaction between alkyl isocyanides and ethynyl phenyl ketone was trapped with
N,N ′-dimethylbarbituric acid to produce alkyl 1,3-dimethyl-2,4-dioxo-7-phenyl-1,3,4,5-tetrahydro-2H-pyrano[2,3-d]pyrimidine-5-carboxamides in good yields.
Corresponding author. E-mail: isayavar@yahoo.com
Received January 8, 2002. Accepted January 14, 2002 相似文献
84.
85.
W. A. Knig S. Lutz M. Hagen R. Krebber G. Wenz K. Baldenius J. Ehlers H. Tom Dieck 《Journal of separation science》1989,12(1):35-39
O-Perpentylated β-cyclodextrin has been evaluated as chiral stationary phase in capillary gas chromatography. Enantioselectivity is observed towards many chiral hydroxy compounds, including cyanohydrins and carbohydrates. Most importantly, the enantiomers of many olefins and alkyl halides can be resolved on this chiral phase. The thermal stability of the cyclodextrin derivative exceeds 200°C. 相似文献
86.
José E. Báez Ángel Marcos-Fernández 《International Journal of Polymer Analysis and Characterization》2015,20(7):637-644
The biodegradable aliphatic oligoesters polyglycolide (PGA), poly(L-lactide) (PLLA), and poly(?-caprolactone) (PCL) with similar number-average molecular weight Mn values but different linear alkyl end groups [CH3?[CH2?CH2]m?CH2?] were compared in terms of their physical properties, parameters such as melting temperature (Tm), crystallinity (xi), long period (L), and lamella thickness (D). They were analyzed by DSC and SAXS. The effect of a longer and nonpolar alkyl end group such as docosyl [CH3?[CH2?CH2]10?CH2?] on the long period (L) was more evident for PCL because it was the most nonpolar species in the family of oligoesters analyzed. 相似文献
87.
Azepinones are available via a one-pot cycloaddition-ring expansion reaction sequence in good yield. The reactions of azepinones with alkyl halides and epoxides were studied. We report herein protocols for the alkylation of azepinones at nitrogen with alkyl halides and epoxides and the isomerizations that occur in the presence of a base. We also report an unexpected ring contraction under oxidative conditions. 相似文献
88.
A pentamodule assembly approach has been established for total synthesis of the naturally occurring (–)‐palmyrolide A and (+)‐5,7‐epi‐palmyrolide A. By using the racemic tert‐butyl carbinol‐containing alkyl iodide, the two diastereoisomeric macrolides could be obtained from the same sequence of reactions, demonstrating the flexibility of the multimodule assembly strategy for diverted total synthesis. 相似文献
89.
Alkyl ketene dimer (AKD) sizing of paper involves the redistribution of the wax over the fibre surface upon heating. The two
major mechanisms widely studied so far are the spreading of an autophobic precursor of molten AKD and AKD vapour transport
and re-deposition on the fibre surface. All previous work assumed that the transport of AKD vapour could be expressed by the
change of water contact angle with substrates that were exposed to the vapour. Information regarding the chemical composition
of the vapour phase above the AKD wax has not been found in the literature. In this work, a simple method for analysing the
chemical composition of the vapour is established. Our preliminary results indicated that the chemical composition of AKD
vapour in the temperature range of 75–80 °C is dominantly fatty acids. This suggests that the sizing effect by actual AKD
molecules via the vapour deposition mechanism is likely to be insignificant in this temperature range. This also implies that
fatty acids play a positive role in AKD sizing. The chemical stability of AKD in this temperature range is also studied. 相似文献
90.
烷基聚葡糖苷溶液的表面吸附平衡与动力学 总被引:3,自引:0,他引:3
用吊片法和气泡最大压力法分别测定了烷基聚葡糖苷(APG)C9.6G1.3水溶液的平衡和动态表面张力,研究了APG水溶液表面的吸附平衡、动力学及其影响因素.测得其cmc(临界胶束浓度)为0.032g/L.吸附过程由初始的扩散控制转变到势垒控制,吸附势垒为4~7kJ/mol.温度升高,平衡和动态表面张力均减小,吸附量增加;加入无机盐,平衡和动态表面张力增大,吸附量亦增加;醇类的吸附使动态表面张力下降速率加快,表明APG与醇分子间有协同吸附作用. 相似文献