共查询到19条相似文献,搜索用时 93 毫秒
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《精细化工经济与技术信息》2004,(1):19-20
N-甲基-邻苯二甲酰亚胺(NMP)主要用于合成4-氨基-NMP,4-氨基-NMP及其衍生物可用于荧光和其它标记研究。它是合成异鲁米诺及其衍生物的重要中间体。 相似文献
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介绍了用作环烯共聚物单体的降冰片烯(NB)的主要用途,对液相反应工艺和气相反应工艺这两种NB合成工艺作了详细的介绍,重点分析了两种工艺的优缺点.文章还对我国环烯共聚物及其衍生物的开发提出了建议. 相似文献
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从工业化的制备角度考虑,通过对工艺路线的选择,确定了工业化合成对二氧环己酮(PDO)单体的最佳工艺路线——由β-羟基乙氧基乙酸盐合成,以氢氧化钠、乙二醇、氯乙酸钠为起始原料,合成的β-羟基乙氧基乙酸钠收率可达80.8%。通过对工艺条件的优化,确定了合成PDO关键步骤的最优条件,即盐酸与β-羟基乙氧基乙酸盐物质的量比为0.95∶1,反应温度为25℃,反应时间为40 min时,产物PDO收率最高。对产物的定性和定量分析表明,通过实验得到了PDO产品,最高收率可达66.2%,但纯度还未达到聚合条件,以后还需对其纯化方法作进一步的探索和研究。 相似文献
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The dynamic implications of increasing returns: Technological change and path dependent inefficiency
Dominique Foray 《International Journal of Industrial Organization》1997,15(6):733-752
This paper addresses the issue of path-dependent selection and inefficiency, counterfactual methods and the empirical evidence employed in this research trajectory. The general message is basically that the theoretical argument to prove path-dependent inefficiency is relatively straightforward, while empirical demonstrations, as well as the analysis of welfare implications are much more difficult. In the first section, we briefly state the basic argument explaining how localized learning leads to an incomplete exploration of the variety distribution of a technology. We then synthesize the most interesting historical studies, which get potential regret results, and ask whether these results suggest a large welfare loss. To try to answer this question, we start from the critical arguments of Liebowitz and Margolis to discuss the theoretical and empirical difficulties of establishing path-dependent inefficiency. 相似文献
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Forecasting volatility in the Singapore stock market 总被引:2,自引:0,他引:2
Volatility forecasting is a major area in the pricing of derivative securities, such as stock and index options. In this paper, we compare three methods of forecasting volatility. These are the naive method based on historical sample variance, the exponentially weighted moving average (EWMA) method, and the generalised autoregressive conditional heteroscedasticity (GARCH) model. Out-of-sample forecasts of monthly return variances generated by these three methods are compared. The results strongly favour the EWMA method.The authors are from the Department of Economics and Statistics, National University of Singapore and the Government of Singapore Investment Corporation respectively. The views expressed in this paper are entirely personal, and do not represent those of any institution. 相似文献
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酸含量测定方法对比及其对生物柴油调合燃料质量的影响 总被引:1,自引:0,他引:1
针对生物柴油调合生产过程中由于酸含量测试方法差异而引起质量波动的问题,分析了GB/T 264-1983、GB/T 4945-2002、GB/T 7304-2000、GB/T 258-1988、GB/T 5530-2005、GB/T 9104-2008等涉及矿物柴油、生物柴油、抗磨剂等调合组分的质量标准中酸含量测试方法中的溶剂、滴定剂、终点判定等因素,指出了不同方法的优势和使用体系。生物柴油调合燃料(B5)生产中原料酸含量表征方式的不统一,密度的差异影响产品酸值合格率的控制。统一酸含量表征方式,选用适宜的试验方法,调整酸含量内控指标,根据矿物油密度优化调合比对控制生物柴油调和燃料(B5)酸值指标、稳定产品质量具有积极作用。 相似文献
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Mauricio R. Bellon David Hodson David Bergvinson David Beck Eduardo Martinez-Romero Yinha Montoya 《Food Policy》2005,30(5-6):476
We explore approaches for targeting agricultural research to benefit poor farmers. Using small area estimation methods and spatial analysis, we generated high-resolution poverty maps and combined them with geo-referenced biophysical data relevant to maize-based agriculture in Mexico. We used multivariate classification and cluster analysis to synthesize biophysical data relevant for crop performance with rural poverty data. Results show that the rural poor are concentrated in particular regions and under particular circumstances. Formal maize germplasm improvement trials were largely outside the core areas of rural poverty and there was little evidence for direct spillover of improved germplasm. Agro-climatic classification used for targeting breeding is useful but often ignores some important factors identified as relevant for the poor. Combining this method with poverty mapping improves stratifying and targeting crop breeding efforts to meet the demands of resource-poor farmers. We believe this integrated approach will help increase benefits from agricultural research to poor rural communities. 相似文献
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烷基多苷(APG)是葡萄糖(或淀粉)与天然脂肪醇在催化剂作用下缩合得到的一种非离子表面活性剂。APG具有优良的表面性能和环境相容性,已经成为新型的绿色表面活性剂,成为近年来的研究热点。对近年来APG的合成方法及其在诸多领域的应用进行了综述。 相似文献