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71.
采用KF/Al2O3催化剂催化合成肉桂酸,用新催化剂催化反应可以降低反应温度。缩短反应时间。提高肉桂酸的产率,探索出了最佳反应条件;当反应温度控制在16℃,苯甲醛和乙酸酐的摩尔比1:3,用6.0gKF/Al2O3催化反应1.0h,得到肉桂酸的产率为85.4%。 相似文献
72.
F-12纤维表面处理对复合材料壳体纤维强度转化率的影响 总被引:4,自引:0,他引:4
对F-12纤维表面进行聚合物涂层改性,通过NOL环复合材料剪切强度测试,研究不同浓度的聚合物表面处理液对复合材料层间剪切强度的影响.结果表明:F-12纤维表面经TDE-85/DDM体系处理后,复合材料层间剪切强度均高于未表面处理的纤维;当刚性涂层液质量分数为5%时,层间剪切强度最高,比未表面处理的纤维高50%左右.φ150mm容器爆破试验结果表明,F-12纤维表面经涂层液处理后,复合材料壳体纤维强度转化率平均提高2.3%,容器特性系数平均提高12.5%. 相似文献
73.
The enantioselective hydrogenation of ethyl pyruvate to (S)-ethyl lactate over cinchonine- and -isocinchonine-modified Pt/Al2O3 catalysts was studied as a function of modifier concentration and reaction temperature. The maximum enantioselectivities obtained under the applied mild conditions were 89% ee using cinchonine (0.014 mmoldm–3, 1 bar H2, 23°C, 6% AcOH in toluene), and 76% ee in the case of -isocinchonine (0.14 mmoldm–3, 1 bar H2, –10°C, 6% AcOH in toluene). Since -isocinchonine of rigid structure exists only in anti-open conformation these data provide additional experimental evidence to support the former suggestion concerning the dominating role of anti-open conformation in these cinchona-modified enantioselective hydrogenations. 相似文献
74.
Hyun Jin Chung Suk Jin Chung Min Ku Jeon Seong Ihl Woo 《Korean Journal of Chemical Engineering》2006,23(2):329-332
The ((Bi3.5La0.5)Ti3O12(BLT) thin-films used in this study were fabricated on a Pt(111)/SiO2/Si(100) substrate by a Liquid Source Misted Chemical Deposition (LSMCD) technique. X-ray diffraction patterns showed that
the BLT films were crystallized and no other phases were observed when annealed above 650 ‡C. Grain size and remnant polarizations
increased with increase in the annealing temperature, while leakage current densities decreased. The remnant polarizations
(Pr) increased from 2.0 to 4.8 and 19.0 μC/cm2 with increase in the annealing temperature from 650 to 700 and 750 ‡C, respectively.
The BLT films annealed at 700 ‡C in O2 showed a good fatigue resistance of reduced polarization by 10% after 109 switching cycles when 9 V of bipolar voltage was applied at a frequency of 40 kHz. 相似文献
75.
In this paper we report a kinetic study of the electro-oxidation of hydrazine catalyzed by vitamin B12 pre-adsorbed on an ordinary pyrolytic graphite electrode. Kinetic parameters were determined by linear sweep voltammetry and rotating-disk electrode polarization curves. The order of the reaction is 1 in OH− ions and Tafel plots give slopes of 80 mV/decade. A possible redox-catalysis mechanistic scheme is proposed. 相似文献
76.
Variable temperature13C MAS NMR spectra are reported for13CO-enriched KFe2Mn(CO)12 as a solid and also as dispersed clusters on a carbon support. The spectrum of KFe2Mn(CO)12 at 300 K agrees with the proposed structure for this cluster and shows that the cluster is static. Two bridging carbonyl resonances are clearly resolved and, by comparison with13C MAS NMR spectra of Mn2(CO)10 and Fe2(CO)9, all terminal resonances for the cluster can be assigned. When the cluster is supported on carbon, two broad resonances are observed at room temperature which are assignable to KFe2Mn(CO)12 and a decomposition product, Mn2(CO)10. The carbonyl ligands in both supported clusters are completely averaged, and KFe2Mn(CO)12 on the carbon surface demonstrates fluxional behavior similar to that observed for the cluster in solution. For this fluxional process, activation energies of 0.6 kcal/mol and 0.5 kcal/mol are estimated for carbon-supported KFe2Mn(CO)12 and Mn2(CO)10, respectively. 相似文献
77.
The anionic polymerization of lauryllactam was initiated at 270°C using sodium hydride as an initiator and N,N′‐ethylene‐bisstearamide (EBS) as an activator (NaH:EBS molar ratio of 2). Polymerization occurred in less than 2 min and was successfully performed in an internal mixer and a twin‐screw extruder with corotating intermeshing screws (Werner & Pfleiderer ZSK 25). The content of residual monomer, as determined by thermogravimetric analysis, was lower than 0.5 wt %. Molecular weight, as measured by size exclusion chromatography, was governed by the lauryllactam:NaH molar ratio calculated on a Mn of 25 kg/mol at a constant NaH:EBS molar ratio of 2. Blends were prepared in situ by polymerization of lauryllactam solutions of various polymers. When poly(ethylene‐co‐butylacrylate) (Lotryl®; Atofina) was dissolved in lauryllactam, rubber‐toughened polyamide 12 blends were obtained. Mechanical properties of the injection‐molded polymers were examined by stress–strain as well as notched Charpy impact tests at different temperatures. Blend morphologies were imaged by scanning electron microscopy (SEM). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 344–351, 2003 相似文献
78.
17O MAS NMR spectra for17O enriched solid heteropoly acid H3PMo12O40 are reported. The oxygen exchange between solid H3PMo12
17O40 and H2
16O vapor at 200–250°C is shown to be accompanied by fast mixing of terminal Mo=O and bridging Mo-O-Mo oxygens in the Keggin unit. The oxygen exchange in H3PMo12
17O40 is much faster than in H3PW12
17O40 in solution as well as in the gas phase. 相似文献
79.
以醋酸锂和钛酸四正丁酯为原料,制备了纯相Li_4Ti_5O_(12),再用简单的水热法合成Li_4Ti_5O_(12)/Fe_3O_4复合材料作为锂离子电池的负极材料,通过XRD、SEM以及电池测试系统对纯相Li_4Ti_5O_(12)和Li_4Ti_5O_(12)/Fe_3O_4复合材料进行了结构、形貌及电化学性能测试。结果表明,制得的复合物具有较好的球形结构且粒径较小(200~300 nm),综合电化学性能较好。由于复合的Fe_3O_4有较高的理论容量,该Li_4Ti_5O_(12)/Fe_3O_4复合材料表现出比纯相Li_4Ti_5O_(12)大的容量,在1.0 C下循环100圈后,Li_4Ti_5O_(12)/Fe_3O_4的放电比容量仍能达到470.2 m A·h/g,同时也表现出比纯相Li_4Ti_5O_(12)更优的倍率性能。 相似文献
80.
本文针对雷达远程故障诊断系统中对故障信息采集的要求,介绍了一种基于nRF401收发芯片无线收发模块的雷达故障信息无线数据采集系统,给出了系统的基本结构和主要功能,对系统的硬件和软件进行了详细设计. 相似文献