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31.
Feng Xian Liu-Cai Charlotte Pham Farida Bey Gilbert Hervé 《Reaction Kinetics and Catalysis Letters》2002,75(2):305-314
Effects of Cs+, H+ and Cu2+ counterions in the vanadium containing heteropoly compounds CsxH1-xVO[PMo12O40] and CsyH0.5-yCu0.25VO[PMo12O40] on the catalytic oxidation of isobutane and characterization by TGA, IR and ESR spectroscopies are reported. A high selectivity of 76% for methacrylic acid and methacrolein together has been obtained with Cs0.75H0.25VO[PMo12O40] catalysts at a reactivity of 5.3x10-1 mmol/h cm3. 相似文献
32.
Brigitte Florin-Michel Marie-France Llauro R. Spitz Q.-T. Pham 《European Polymer Journal》1979,15(3):277-283
Ethylene 1-hexene copolymers obtained by catalytic polymerization have been examined by 1H and 13C NMR. Copolymer compositions have been determined by 1H NMR and i.r. and the sequence distributions for 1-hexene by 13C NMR. Variations of the copolymer microstructure have been related to the experimental conditions for copolymerization. 相似文献
33.
Ethanol was found to give a metastable crystalline phase (crystal-II) when the liquid was cooled at a moderate rate. Glassy states of liquid and of newly found crystal-II were obtained in the calorimeter cell by controlling the cooling rate of the liquid. The heat capacities of these phases as well as that of the stable crystal-I were measured by an adiabatic calorimeter in the temperature range between 14 and 300 K. The glass transition temperature Tg, the heat-capacity jump at Tg, and the residual entropy were found to be 97 K, 35.3 J K?1 mol?1, and 8.93 J K?1 mol?1 for the glassy liquid, and 97 K, 22.8 J K?1 mol?1, and 4.24 J K?1 mol?1 for the glassy crystal-II, respectively. The values for the residual entropy are referred to the third-law entropy for crystal-I.The heat capacities reported previously for the supercooled liquid by Gibson et al. and by Parks and Kelley agree well with those for the metastable crystal-II. Those of the supercooled liquid connect smoothly with those obtained for the liquid above the melting temperature. Thus, ethanol is found to be another example of a low-molecular-weight compound which shows multiple glass-transition phenomena. 相似文献
34.
Christian Pichot Marie-France Llauro Quang-Tho Pham 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2619-2633
The compositions and sequence distributions of vinyl acetate–butyl acrylate copolymers obtained with batch and semicontinuous emulsion polymerizations have been studied by 1H and 13C NMR. The batch process gives heterogeneous copolymers while with the semicontinuous one the sequence distribution is statistical. These differences in sequence distributions have been related to the physical properties of the copolymers. 相似文献
35.
The kinetics of the reaction NH2 + NO → N2 + H2O were studied, using a conventional flash photolysis system. A value of k1 = (1.1 ± 0.2) × 1010 & mole?1 s?1 was obtained at room temperature and in the pressure range 2–700 torr in the presence of nitrogen. A slight negative temperature coefficient was observed between 300 and 500 K, equivalent to a negative activation energy of 1.05 ± 0.2 kcal mole?1. 相似文献
36.
Pham TN 《Physical review D: Particles and fields》1992,46(7):2976-2981
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39.
α-n-amylcinnamaldehyde (jasminaldehyde) was obtained with 82 % yield by solid-liquid phase transfer catalysis without solvent within 3 days at room temperature. By use of domestic microwave irradiation, the same yield was obtained within 1 minute at a power of 600 W. 相似文献
40.
The aim of this paper is to control the rate of convergence for central limit theorems of sojourn times of Gaussian fields in both cases: the fixed and the moving level. Our main tools are the Malliavin calculus and the Stein method, developed by Nualart, Peccati and Nourdin. We also extend some results of Berman to the multidimensional case. 相似文献