The Synthesis of 1,4-Diazabicyclo (2.2.2) Octane over a Pre-Treated Titanium Silicalite-1 Catalyst

Potassium chloride salt pre-treated titanium silicalite-1 (TS-1) zeolite (K-TS-1) was prepared via an ion-exchange method. XRD, EDX and BET were used to identify the structure of the zeolite. The BET surface area and the adsorption/desorption cumulative pore volume of the K-TS-1 catalyst were about 297 m²/g and 0.213 cm³/g, respectively. The average pore diameter of the K-TS-1 catalyst was 29.49 Å. The catalytic activity of K-TS-1 catalyst was studied in the fixed-bed catalytic reactor. 1,4-Diazabicyclo (2.2.2) octane (DABCO) was prepared from ethylenediamine (EDA) over the K-TS-1 zeolite catalyst. The influences of various reaction parameters such as reaction temperature, space velocity and concentration of EDA were discussed. The conversion of EDA was more than 96% and the selectivity of DABCO and PIP were up to 64 and 30%, respectively, in the temperature of 340 °C and weight hourly space velocity of 1.5 h^?1 in the presence of water.     

超临界流体中的酶催化

与其他非水相酶催化介质相比 ,超临界流体有其独特的优越性。阐述了超临界流体的概念、对超临界流体的选择原则以及在超临界流体中酶催化的各种影响因素 ,还讨论了在此类流体中酶催化的应用和发展前景     

国内中小皮化企业如何适应激烈的市场竞争

总结了目前国内中、小皮化企业中存在的主要问题 :自主开发能力差 ,造成产品品种单一、配套性差 ;新产品市场推广能力也较差 ,造成即使有好的产品 ,也无法打开市场 ;而普遍存在的制革厂欠款 ,皮化企业自身体制陈旧及国外皮化公司的进一步本土化策略 ,使国内皮化企业面临更严峻的挑战。根据自身多年经营皮化材料的经验 ,提出了切实可行的应对措施     

“两步法”求取双目视觉传感器中摄象机位置关系

根据平行线“消隐点”理论，提出了用于双目视觉传感器自标定的“两步法”。该方法仅需４对消隐点象面坐标便可线性求解出旋转矩阵，再用２个空间点坐标便可线性求解出平移矢量。     

铸造合金凝固过程瞬时应力的测试

以计算机采集处理系统为手段,测试了应力框铸件凝固过程的瞬时应力.结果表明,该方法简便、速度快,精度高,可获得铸件凝固过程瞬时应力及温度的动态变化过程。     

Rapid synthesis of La0.7Sr0.3MnO3+λ catalysts by microwave irradiation process

Microwave irradiation processing (MIP) was considered as a potential method to synthesize perovskite-type oxides rapidly, cleanly and energy-efficiently. In this paper, La_0.7Sr_0.3MnO_3+λ, a kind of promising catalyst for automobile exhaust purification, was successfully prepared by MIP in not more than 5 min. The sol–gel method was also used for comparison. All the samples were evaluated by catalytic activity tests in the simulated exhaust and characterized by XRD, BET, TEM and XRF analyses. The results showed that the integrated perovskite-type phase and uniform particle size were obtained in the microwave-treated samples. And those ones exhibited a better oxidation activity under slightly oxygen-rich condition than that by sol–gel method, which may be related to more A-site cation vacancies and larger bulk oxygen content generated in MIP. Possible formation mechanism of perovskites in MIP was also discussed.     

沙河抽水蓄能电站机组运行缺陷浅析

沙河抽水蓄能电站两台50 MW可逆式机组自投运以来,总体情况良好,但是也出现了一些缺陷,如机组同期装置故障,机组冷却水流量或压力不足,静止变频器故障,励磁过电流故障等。对于出现的缺陷,电站进行了分析和处理,提高了机组的起动可靠度。     

Comparison of prototype and rote instruction of English names for Chinese visual characters

This study compared prototype and rote instruction of English names for Chinese visual characters. In the prototype condition, participants were taught the meaning of the prototype that served as the distinctive feature of multicomponent characters. In the rote condition, participants traced the character and wrote its translation. Participants learned more rapidly and maintained more words in the prototype condition.     

光学活性物质的工业生产方法

本文介绍了光学８活性牺牲垢几种工业规模的生产方法及最新的进展，分析了各种方法的特点及存在的问题。