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161.
用50W连续波CO_2激光器为热源,诱发SiH_4和C_2H_4反应,合成SiC超细粉末。实验确定了反应腔体内压力p、气源中的C/Si原子比、喷嘴内径2r以及激光功率密度与粉末特性之间的关系,并对合成的产物进行物理、化学表征。 相似文献
162.
环氧油一步合成的反应机理和动力学研究 总被引:11,自引:0,他引:11
杭晓敏 《化学反应工程与工艺》1996,12(1):1-8
研究了环氧油一步合成的反应机理和动力学;结合实验结果和理论分析动力学模型,首次提出:在适当的反应条件下,油脂的一步环氧化反应动力学模型可以表示为过氧酸生成反应动力学模型;其实验动力学模型方程为:r0=k[H2O2](0.99)[HOAc](0.97),其中k与催化剂用量有关。 相似文献
163.
Zhonghua LIU+ Chunpeng LIU Dept. of Metallurgy Kunming Institute of Technology Kunming China 《材料科学技术学报》1993,9(2):136-138
Reduction of stibnite with hydrogen in the presence of calcium oxide has been experimentally inves-tigated at moderate temperature. The results reveal that the effluent generated in the reduction pro-cess contains much less air-polluting substance H_2S, and that the reaction activation energy is63. 3 kJ/mol. The form of antimony changes considerably when the reaction temperature varies. 相似文献
164.
The photoconductive properties of a carotenoid polyene,β-Apo-8′ carotenal in polycrystalline form has been studied. The growth of the photocurrent shows an overshoot in the growth-time
curve before steady state value is attained. This behaviour of photocurrent is proposed to be due to higher value of recombination
coefficient than trapping coefficient. From the temperature dependence study it is observed that the steady state photocurrent,
at first increases with increase of temperature, attains a maximum at a particular temperatureT
max and then decreases with temperature. TheT
max value agrees with the temperature above and below which steady state photocurrent is attained differently. Monomolecular
and bimolecular recombination processes at two temperature regimes are proposed to account for the observed behaviour. The
dependence of photocurrent with excitation light intensity and wavelength study provide information on the carrier generation
processes. The fast decay of photocurrent have been observed at different temperatures and from this study the decay constant
is calculated and it is found to be temperature independent. 相似文献
165.
In this work we investigated the mechanism of the electrochemical intercalation reactions in rf sputtered nickel oxide thin films electrodes by two techniques: mechanical stress change measurements by means of an optical technique and mass changes using an electrochemical quartz microbalance (EQCM). The experiments were performed in alkaline electrolytes containing cations of the first column of the periodic table. Reversible mass and volume changes were observed. In order to explain these experimental results, an exchange reaction is proposed, in which the oxidation process is accompanied by the deinteractional of a relative large number of “light” cations, simultaneously with the intercalation of a smaller number of heaviest cations. 相似文献
166.
提高铌钽标准液显色反应能力并延长其有效贮存期的分光光度法研究 总被引:3,自引:0,他引:3
施绍银 《广东有色金属学报》1996,6(2):138-144
铌,钽的酒石酸,柠檬酸,草酸铵标准液的显色反应能力及有效贮存期,同铌,钽的原始标准溶液pH有很大关系,铌酒石酸标准液(原始溶液pH1.4),其显色反应能力仅在80%~50%之间(视放置时间长短而异),但如何采用pH4.5~5.0的铌酒石酸标准液,其显色反应能力达100%,即使贮存440d后,仍能保持原有的显色反应能力,铌柠檬酸标准液(原始溶液pH1.2),无论用本法(Nb-BPR-CPB法)还是用 相似文献
167.
相转移法制备高纯超细TiO2技术研究 总被引:9,自引:0,他引:9
报道了用相转移法制备高纯超细TiO2的新技术;探讨了Ti(Ⅳ)从有机相转移到水相发生水解反应的机理 ;通过TG-DTA分析以及XRD物相分析对水解产物的组成、热分解机理,晶型转变规律进行了研究,建立了水解产物焙烧的最佳温度。 相似文献
168.
The kinetics of spherulite radial growth and the morphology of the compatible system PEO/PVC have been studied by optical microscopy. The usual spherulite radial growth behaviour has been found for compatible blends with PEO content higher than 70%. For lower composition, distortion of the usual spherulite morphology has been observed; the anomalies have been attributed to partial miscibility of the components. 相似文献
169.
Fusae Nakanishi 《Polymer International》1992,27(3):237-241
Preparation of photoreactive Langmuir-Blodgett (LB) films was carried out using polymers/oligomers prepared from long-chain dialkyl esters of di-and tetra-olefins and having cyclobutane rings in the main chain. These polymers/oligomers formed stable monolayers on a water surface when mixed with arachidic acid. These monolayers could be deposited onto a substrate successfully forming Y-type films. The oligomer LB films were polymerized on irradiation. The polymer LB films showed a photo-reversible process between polymers and oligomers, depending on wavelength of the irradiating light. On the basis of spectral data and molecular weight change, this behaviour was found to be caused by cleavage and formation of cyclobutane rings. 相似文献
170.
B. E. Elizalde M. Dalla Rosa C. R. Lerici 《Journal of the American Oil Chemists' Society》1991,68(10):758-762
Maillard reaction volatile compounds (MRV), prepared by heating a glucose-glycine solution, were tested as antioxidants in
soybean oil (SBO) thermoxidation. The volatiles were transferred into the oil by stripping with a stream of Nitrogen and substituting
the atmosphere above the oil with air containing MRV. Standard accelerated oxidation was performed by heating the SBO. Peroxide
value measurement and headspace gas Chromatographic analysis were carried out on all the samples. The MRV antioxidant activity
was evaluated by determining the effect of the induction period and the kinetic rate constant of peroxide and oxidation volatiles
formation. The MRV showed a significant antioxidant activity. The effectiveness was variable depending on MRV transfer method
to the oil, and the Maillard reaction extent was related to the browning level of glucose/glycine solution. It was found that
the maximum effect of MRV prolonged about three times the induction period and reduced the kinetic rate constant by half in
relation to the control sample. MRV affects oxidative stability of soybean oil by lengthening the induction period as well
as by decreasing the rate of oxidation at the propagation state and reducing the formation of hexanal. 相似文献