排序方式: 共有39条查询结果,搜索用时 15 毫秒
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本文在385—485 ℃、压力约100 atm条件下对四氢萘热解反应动力学进行研究。热解产物的定性鉴定表明, 四氢萘主要发生脱氢反应生成萘和异构化反应生成甲基茚满。由α-C_B-C键断裂生成丁基苯反应则较少。反应产物中还有少量茚满、甲苯、乙苯等, 它们分别来自甲基茚满和正丁基苯的进一步裂解。本文对复杂的四氢萘热解反应作了定量处理, 进行了较详细的动力学研究,求得了相应的速率常数、活化能和指前因子。在实验结果基础上, 借助热化动力学计算, 参考一些文献结果, 提出了四氢萘热解反应机理。由该机理出发所得的各产物速率方程与实验结果基本吻合。 相似文献
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MoOS_2(S_2CNEt_2)_2是含有Mo(S_2)基团的模型化合物,对它的研究有助于了解某些钼酶活性中心的本质。该化合物的结构研究已有较详尽的报道,而动力学研究的报道甚少。本文着重探讨各种动力学参数与溶剂特性之间的关系。 相似文献
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Superhard nanocomposite nc-TiC/a-C:H film fabricated by filtered cathodic vacuum arc technique 总被引:1,自引:0,他引:1
Yaohui Wang Xu Zhang Xianying Wu Huixing Zhang Xiaoji Zhang 《Applied Surface Science》2008,254(16):5085-5088
Superhard nanocomposite nc-TiC/a-C:H films, with an excellent combination of high elastic recovery, low friction coefficient and good H/E ratio, were prepared by filtered cathodic vacuum arc technique using the C2H2 gas as the precursor. The effect of C2H2 flow rate on the microstructure, phase composition, mechanical and tribological properties of nanocomposite nc-TiC/a-C:H films have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy disperse spectroscopy (EDS), microindentation and tribotester measurements. It was observed that the C2H2 flow rate significantly affected the Ti content and hardness of films. Furthermore, by selecting the proper value for C2H2 flow rate, 20 sccm, one can deposit the nanocomposite film nc-TiC/a-C:H with excellent properties such as superhardness (66.4 GPa), high elastic recovery (83.3%) and high H/E ratio (0.13). 相似文献
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A novel MI-insensitive and filterless frequency octupling scheme based on two parallel dual-parallel Mach–Zehnder modulators (DP-MZMs) is proposed. The proposed scheme is not sensitive to modulation index and relatively strong MMW signal with good radio frequency spurious suppression ratio (RFSSR) can be obtained without strict requirement on modulation index. Filterless feature makes the scheme quite suitable for wavelength division multiplexing (WDM) applications. For verification, a 60 GHz millimeter wave with 44 dB RFSSR is generated from a 7.5 GHz radio frequency wave by simulation. Performance of the proposed scheme has been characterized under different conditions including DC-bias drifts of MZMs, different amplitudes of RF inputs and different extinction ratios of MZMs. 相似文献
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Metal ion exchanged montmorillonites (AlM & CrM) and metal oxide pillared montmorillonite (AlPM & CrPM) were prepared and characterized with XRD, FT‐IR, nitrogen adsorption and TPD of ammonia. The pillaring process results in a remarkable increase of interlayer distance, surface area and acid amount of the catalyst. However, increasing the calcined temperature causes reverse effects for the CrPM catalyst. The acid amount decreases in the order of CrPM200 < CrPM300 < AlPM500 < CrM < CrPM400 ≥ CrPM500 ≥ AlM. In the dehydration of 2‐propanol to propene, the reaction follows first order kinetics and the apparent rate constant is related to the catalyst acid amount. Compensation effect occurs in this reaction over the series of catalysts. 相似文献
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Intermediate product of the reaction of MoOS2(S2CNR2)2 and PPh3 in dichloroethane has been detected by ESR spectroscopy. Two ESR signals have been observed at low temperature in the reaction system which was stopped by quenching it in liquid nitrogen. The g values are 2.020 ± 0.001 and 1.972 ± 0.001 respectively. The signal at g = 2.020 is attributed to a reaction intermediate with pentavalent molybdenum. A reaction mechanism has been proposed which is consistent with the observation of pentavalent molybdenum as the intermediate in the process of reaction. 相似文献
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