直接氯化法合成对硝基氯化苄

介绍了以对硝基甲苯和氯气为原料 ,在催化剂存在下合成对硝基氯化苄的方法 ,考察了催化剂种类、反应温度、溶剂配比等因素对反应的影响 ,优化的反应条件为 :对硝基甲苯用量 1 3 7g,对硝基甲苯 /邻二氯苯 (摩尔比 ) =1∶ 0 .6,w (偶氮二异丁腈 ) =0 .6% ,反应时间 3 h,反应温度 1 60℃ ,产物单程收率大于 65 % ;将反应混合物中未反应的原料分离后 ,以无水乙醇为溶剂结晶纯化 ,物料 /溶剂 (摩尔比 ) =1∶ 1 .5时晶体含量在 99.0 %以上 ,结晶收率达 67     

Is evidence-based practice diverse enough? Philosophy of science considerations.

In its policy rationale for evidence-based practice in psychology (EBPP), the APA Presidential Task Force on Evidence-Based Practice (see record 2006-05893-001) claims to have constituted itself with "scientists and practitioners from a wide range of perspectives and traditions, reflecting the diverse perspectives within the field" (p. 273). We applaud this attention to diversity but contend that an entire perspective of the debate was omitted in the Task Force's newly approved policy and its underlying report. The failure to consider a philosophy of science perspective led the Task Force to make a number of epistemological assumptions that are not based on evidence or rationale and that thus violate the very spirit of evidence-based decision making. In this comment, we reveal a few of these assumptions and discuss their detrimental consequences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emission of trace toxic metals during pulverized fuel combustion of Czech coals

A study of the trace elements emission (As, Se, Cd, Co, Cr, Cu, Zn, Hg, Tl, Pb, Ni, Sn, Sb, V, Mn and Fe) from pulverized coal combustion has been made at six heating and power stations situated in the Czech Republic. The amount of chlorine in coal has considerable influence on volatilization of some elements such as Zn, Cu, Pb, Hg and Tl, which is explained by the formation of thermodynamically stable compounds of these elements with chlorine. Generally, the affinities for Cl follows the order Tl > Cu > Zn > Pb > Co > Mn > Sn > Hg. The experimental data indicates enrichment of some of the trace toxic elements in the emissions (Cu, Zn, As, Se, Cd, Sn, Sb, Hg and Pb) and good agreement was obtained by thermodynamic equilibrium calculations with a few exceptions. In the case of Fe, Mn, Co, Cr and Sn calculated values are overestimated in the bottom ash and there are zero predicted amounts of these elements in the fly ash. In comparison, the results from experiments show up to 80% of these elements retained in fly ash. This implies that there exist additional steps leading to the enrichment by Fe, Mn, Co, Cr and Sn of small particles. Such mechanisms could include the ejection during devolatilization of small inorganic particles from the coal of bottom ash particles, or disintegration of the char containing these metals to small particles of fly ash. On the other hand, there are slightly overestimated or similar values of relative enrichment factors for As, V, Cu, Cd, Sb, Tl and Pb in the fly ashes and zero predicted values for bottom ashes. Our experimental results show about 5% or less of these elements are retained in bottom ashes, so they probably remain in the bottom ash inside unburned parts of coal. Copyright © 2003 John Wiley & Sons, Ltd.     

ATM网络的可用比特率业务

本文介绍了可用比特率业务的业务特点，速率控制机制以及该业务存在的问题。     

A new approach to the mechanism of chlorine evolution: Separate examination of the kinetic steps using ac impedance on a rotating thin ring electrode

In the absence of a bulk diffusion effect, it is shown for the first time that the impedance spectra for the chlorine evolution reaction on a rotating thin ring electrode comprise three consecutive semicircles in the capacitive half of the complex plane. The first (highest frequency) semicircle is due to the charge-transfer resistance for chloride discharge and the simultaneous chlorine adsorption coupled to the double-layer capacitance. The second semicircle (around 5 Hz) is due to the adsorption and desorption of a chlorine intermediate. The third (lowest frequency, around 0.5 Hz) semicircle is due to the relaxation of surface oxygen species. The impedance data allow the steps of the overall reaction to be examined individually. On a Pt surface the rate of chloride discharge and simultaneous chlorine adsorption (the admittance of the first semicircle) is first order with respect to chloride concentration and has a potential-dependence close to 58 mV/decade. The rate of the adsorption and desorption process (the admittance of the second semicircle) is second order with respect to chloride concentration, and has a potential dependence close to 30 mV/decade. The time constant for the adsorption/desorption processes is ca 20 ms, independent of electrode potential in the range studied. These features are consistent with a mechanism in which a faster discharge reaction (Cl⁻ Cl_ad + e) is followed by a slower surface combination reaction (2Cl_ad → Cl₂), but inconsistent with mechanisms in which ion + atom desorption is predominant, the initial chloride discharge is slow, or a unipositively charged chlorine species is involved.     

微絮凝接触过滤处理低浊度含藻水的研究

通过现场试验，对微絮凝过滤处理生活用水所带来的一系列问题进行了详细、科学的分析，在大量试验数据基础上对产生问题的原因进行了研究并取得了初步结论。在此基础上，提出了改进措施，取得了实效。     

调整我国产业结构的若干思考

在国有企业产权制度改革中，改革不合理的产业结构是主要内容之一。不合理的产业结构带来了资产流量与存量产出效益的巨大损失，并放大了市场信号的失真度。因此强化产业结构的调整，是深化经济体制改革，使国民经济持续发展的保证。本文在分析产业结构不合理现状的基础上，提出了对调整我国产业结构的见解。     

氯气泵叶轮连续破碎原因

针对YLJ型液环式氯气泵叶轮在短期内频繁破碎的情况,对其破碎原因进行了分析,并提出相应的改进措施,使烧碱工艺系统保持了长、满、安、稳的运行状态。     

氯碱生产中的腐蚀与防护

介绍了氯碱装置中介质的腐蚀特性、常用材料的耐腐蚀特性及应用实例。     

Occurrence and Preclusion of Terpene Chlorohydrins in Citrus Essential Oils

ABSTRACT: Screening commercial cold-pressed oils revealed the presence of terpene chlorohydrins, which may have quality and safety implications for end-users. Concentrations of (1R, 2R, 4R)-2-chloro-8- p -menthen-1-ol in some citrus essential oils ranged from less than 1 to 140 ppm. More than half of the oils tested contained less than 2 ppm of (1R, 2R, 4R)-2-chloro-8- p -menthen-1-ol. A pilot plant study used different concentrations of chlorinated water during the oil-recovery process. Cold-pressed oil, produced from a 30-ppm chlorine solution, contained (1R, 2R, 4R)-2-chloro-8- p -menthen-1-ol at detection threshold. The presence of (1R, 2R, 4R)-2-chloro-8- p -menthen-1-ol in citrus essential oils results from processing conditions and can be reduced through the reduction of chlorine levels in treatment water.