Ammoxidation of methylaromatics over vanadium phosphate catalysts II. Catalyst formation, active sites and reaction mechanism

The interactions of VOHPO₄· 0.5H₂O and (VO)₂P₂O₇ with the ammoxidation feed and the single components such as ammonia, oxygen, water and component mixtures were studied in detail using XRD and temperature-programmed reaction spectroscopy. The aim of this work was to improve the knowledge of the formation of the active phases or active sites of the catalysts from their precursors under the condition of the ammoxidation reaction. Similar catalytic properties of various applied VPO materials were discussed in terms of the presence of similar structure elements (domains of adjacent edge-sharing VO₆ octahedra-units and P-O-NH₄ groups).     

MIM隧道结的电子输运特性和发光研究

论述作为一种新型发光器件的ＭＩＭ隧道结的发光机理，报告了该器件的发光现象和Ｉ－Ｖ特性曲线中负阻现象的实验观察。数据显示，结中表面等离极化激元（ＳＰＰ）与粗糙度的耦合是引起光发射的主要方面，ＳＰＰ对隧穿电子的阻塞作用导致了电子输运中的负阻现象。此外，还观察到了直接辐射的紫外峰。     

The desorption of O2 during NO and N2O decomposition on Cu- and Fe-zeolites

The decomposition of NO and of N₂O over a CuZSM-5 zeolite and a Fe-mordenite, respectively, has been studied using tracer techniques. The results demonstrate the high mobility of the lattice oxygen ions in self-diffusion. They afford a possible explanation for the problem of how two extralattice oxygens located at positions remote from each other may combine to form the O₂ molecules which are spontaneously desorbed in these redox reactions. They show that a portion of the lattice oxygen mixes into the O₂ released on decomposition. The data also show that N¹⁸O and N₂ ¹⁸O undergo exchange with the catalyst oxygen under reaction conditions.On leave from Central Research Institute for Chemistry, Hungarian Academy of Sciences, H-1525 Budapest, Hungary.     

电站装备失效分析及其预防

简叙了电站装备失效分析程序、失效原因及其失效机理。大量的各种各样的失效，常常涉及一种或多种的失效机理。在众机理中，主要是：腐蚀失效、环境断裂失效、变形失效和断理解失效。     

DFMC在水利机械产品开发中的应用研究

分析了DFMC(大规模定制设计)关键技术及相关技术,提出了运用该项技术开发产品企业应作好的前期准备,研究了水利机械产品"大型移动启闭机"的定制开发。     

对新闻专业主义“现实性”的思考

新闻专业主义在西方拥有很大的理论市场,但这一理念所具有的理想主义色彩也不容忽视。多年来,新闻专业主义在其发展过程中不断受到严峻的现实挑战。本文分析了新闻媒体新闻专业主义缺失的深层原因,认为政治权力和市场机制等制度性框缚是新闻专业主义难以发挥其预期效果的根源所在。同时指出,新闻专业主义并非新闻改革的唯一出路。     

Cathodic reduction of acids in dimethylformamide on platinum

A linear correlation was shown to exist between the acidity and the cyclic voltammetric half-potential of the reduction of acids in DMF for carboxylic and N-acids in the pK_a range of 6-16. Chlorophenols are reduced at slightly lower potentials giving a separate parallel line. Applying the obtained equation and employing the same method to literature data in DMSO, the pK_a values for conjugate aids of DMF and DMSO can be calculated, showing DMSO·H⁺ to be more acidic (pK_a = 2.9) than DMF·H⁺ (pK_a = 5.7). The analysis of cyclovoltammetric data demonstrated that a CE mechanism operates in the reduction of strong acids, including the conjugate acid of DMF. Weaker acids are reduced by direct discharge or a mixed mechanism.     

磨削加工中磨削液对砂轮堵塞影响的试验分析

砂轮堵塞是影响砂轮耐用度的重要指标，磨削液在磨削加工中起到润滑、冷却、清洗等作用，对砂轮的堵塞有着较大影响．文章通过试验，分析了磨削液对砂轮堵塞的原因．     

绿色润滑剂的生物降解性及特点

阐述了绿色友好润滑剂的生物降解性和摩擦化学特点，提出了绿色润滑剂在发展过程中存在的主要问题，并对未来的发展趋势进行了预测。     

曙—区超稠油间歇蒸汽吞吐技术探讨

针对曙-区超稠油井进入高周期后产量递减，成本上升的矛盾，提出用间歇吞吐技术改善高周期蒸汽吞吐效果，通过对吞吐机理和现场实际资料统计的分析。对这项技术实施的条件及效果进行了探讨。结果表明，该项技术在高周期井实施效果较好。具有较好的推广前景。