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451.
水蒸气抑制甲烷燃烧和爆炸实验研究与数值计算 总被引:2,自引:1,他引:2
在爆炸激波管中对水蒸气抑制甲烷燃烧和爆炸进行较系统的实验研究,并对其抑燃、抑爆化学动力学作用机理进行数值计算分析。结果表明:加入一定量的水蒸气后,可以有效降低CH4-O2混合气体的燃烧速度和爆炸强度;当水蒸气量达到某临界值时,CH4-O2混合气体将不能被点燃。化学动力学数值计算结果表明:在混合气体中加入水蒸气后,增大了甲烷的点火延迟时间,降低了燃烧温度和H,O和OH等高活性自由基的浓度。水蒸气能有效抑制甲烷燃烧和爆炸,其作用效果源于其物理抑制和化学阻化的综合效应。 相似文献
452.
将人体划分为四个节段,并对每个节段的不同姿势进行编码,实现了维修作业姿势的参数化定义,由12位健康的男性被试者参加,根据主观感觉利用自由模量幅度估计法对这些姿势的舒适性进行了评价和分级,得出了各种作业姿势的舒适级别,实现了对作业姿势舒适性的定量评价。 相似文献
453.
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455.
China produces the largest amount of pork in the world, which emits the largest amount of greenhouse gases (GHGs). This paper calculates GHG emissions from China’s hog production at the provincial level using newly published emission factors. Empirical results show that GHG emissions from China’s hog production mainly respond to the scale intensity. Capital abundance and income contribute positively to GHG emissions from hog production. Pork trade increases GHG emissions from China’s hog production with a significantly direct effect, reduces GHG emissions through indirect technique effects. 相似文献
456.
457.
Male costs and benefits associated with male display size in field populations of an Australian lekking Drosophila species were examined. Results suggested that male mating success increased with display size, since matings appeared to
be more common in large displays, and since the probability of males encountering a female increased as displays contained
more males. Female encounter probabilities did not increase once about 20 males or more were present on a display. Male size
and fighting costs tended to increase with display size. The distribution of males among displays did not follow the ideal
free distribution in the sense that each male did not have equal mating opportunity per unit time. Deviation from an ideal
free distribution may have been due to female preference for mating in aggregations rather than with solitary males, since
in a field experiment females were more willing for mating in an aggregation of five males than with solitary males.
Received: 22 May 1997 / Accepted after revision: 1 November 1997 相似文献
458.
稀水溶液中Cr(Ⅵ)光化学还原的研究 总被引:5,自引:2,他引:3
研究了稀水溶液中Cr(Ⅵ)的光化学还原过程,考察了·OH自由基俘获剂的种类、结构及溶液pH值对Cr(Ⅵ)还原的影响结果表明稀水溶液中Cr(Ⅵ)的还原过程分化学还原与光化学还原两步进行,前者为直接氧化还原过程,后者则经历自由基反应;·OH自由基俘获剂中羟基的数量和位置对Cr(Ⅵ)的还原均有影响,羟基α位碳上氢原子数量愈多,碳氢键强度愈小,愈有利于Cr(Ⅵ)还原;溶液pH值对Cr(Ⅵ)的还原有重要影响,随着pH值的升高,其还原率和反应速率均下降,当pH≥70时,Cr(Ⅵ)的还原基本停止 相似文献
459.
At the centre of the debate surrounding sustainable development is a recognition that companies can make a major contribution by being environmentally and socially responsible and that tools associated with these concepts can enhance the competitiveness and economic performance of the firm. In this paper we go further in arguing that in a world of globalisation it is equally important to look at issues of international trade. In an examination of free trade we argue that it is neither fully consistent with sustainable development nor to the benefit of business. We point to a new imperative to develop sound sourcing, and equitable and fair trading relationships. We identify issues associated with fair trade (including issues of human rights, fair wages, sustainability reporting procedures and codes of conduct on ethics) and associated tools of analysis (guaranteed prices, codes of conduct and end price audits). The paper argues that in a world of globalisation with greater transparency and information availability it will be important for companies to be clear about their policies on supply chain management and trade. Indeed, with the growth of an active and sophisticated civil society, it will be argued that policies associated with sound sourcing, equitable trade and fair trade could provide companies with a new competitive strategy based on ethical standards communicated to the consumer through a strategy of differentiation. We explore strategies for the integration of fair trade policies, strategies and standards, and the opportunities for new markets and niches that this presents. It is argued that the integration of fair trade into a business strategy can enhance competitiveness. 相似文献
460.
无汞开管法快速测定工业废水中的COD 总被引:1,自引:0,他引:1
采用无汞开管法测定 COD。方法使用硫酸 -磷酸介质、重铬酸钾氧化体系 ,以硫酸银作催化剂 ,其他试剂包括硝酸银和硫酸铬钾以排除氯离子的干扰。样品在玻璃试管中进行消化 ,用一台恒温器加热样品 ,反应温度 1 65℃ ,加热时间只需 1 0 min,消解后剩余的重铬酸盐用分光光度法或滴定法测定。试验结果表明 ,本法的检出限为 1 0 .9mg/ L,测定范围为 3 0~ 1 5 0 0 mg/ L。由于方法不使用剧毒的汞盐 ,也就避免了汞对环境的污染。应用本法测定了大批量工业废水样品 ,结果令人满意 相似文献