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鼠李糖脂是一种阴离子生物表面活性剂,不仅具有表面活性剂增溶、破乳、消泡等特性,还具有低毒、环境友好、易降解等优点。鼠李糖脂是由铜绿假单菌在特定条件下发酵产生,发酵液的分离纯化成为制约其产量及纯度的关键因素。文章对鼠李糖脂发酵液常用的分离纯化方法进行了综述,论述了不同分离方法的优缺点。 相似文献
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交叉口是城市干道重要的组成部分,干道的通行能力主要是由关键交叉口的通行能力决定的。解决交叉口的交通冲突,就理论方面分析有两种方法:一是空间分离,如渠化、立交等;二为时间分离,如信号控制法、多路停车法及让路法等。交通信号的作用是从时间上将相互冲突的交通流予以分离,使其在不同时间通过,以保证行车安全,同时交通信号对于组织、指挥和控制交通流的流向、流量、流速以及维护交通秩序等均有重要的作用。 相似文献
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记者3月1日从山东维尔斯化工有限公司获悉:该公司采用目前国内最先进、最成熟的酯交换法新工艺和后续精馏分离工艺等技术,投资1亿元人民币建设的、我国目前单套生产能力最大的2.5万吨碳酸二甲酯、3万吨碳酸丙烯酯和1、2-丙二醇联合装置于去年12月18日一次开车成功,经过两个多月连续稳定工业化考核,主要经济技术指标达到国内先进水平,主要产品碳酸二甲酯、碳酸丙烯酯和1、2-丙二醇的纯度分别达到99.7%、99.5%和99.8%。产品质量全部达标,优级品率达到100%。 相似文献
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40多年来,由于气相色谱在高效分离和检测方法等方面的不断发展,使其应用范围不断扩大,现已成为石油、化工、环境保护、食品、医药、法检、临床和超纯材料等领域中分离、分析的一种重要的、必不可少的手段.近年来气相色谱法在分离方法、联用技术、样品改性、浓缩、分离方法优化以及色谱专家系统等方面都取得了很大进展. 相似文献
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本文基于中观及微观研究视角,从多粒度层次、全生命功能周期及供应链责任体3个维度,构建面向不确定性的多粒度产品供应链碳足迹分析模型。利用鱼刺图法和结构方程法设计静态产品碳足迹量化公式,改进粗糙集法动态解析不确定性。选取液晶显示器为实证进行分析,再拓展研究对象样本集,运用统计方法三维解析样本集碳足迹,绘制影响热度图,寻找优化产品供应链碳足迹的关键环节。 相似文献
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The study analyzes ex ante the adoption of insect-resistant Bt eggplant technology in India. Farmers’ willingness to pay (WTP) is estimated using the contingent valuation method. Given the economic importance of insect pests in eggplant cultivation, the average WTP for Bt hybrids is more than four times the current price of conventional hybrid seeds. Since the private innovating firm has also shared its technology with the public sector, proprietary hybrids will likely get competition through public open-pollinated Bt varieties after a small time lag. This will reduce farmers’ WTP for Bt hybrids by about 35%, thus decreasing the scope for corporate pricing policies. Nonetheless, ample private profit potential remains. Analysis of factors influencing farmers’ adoption decisions demonstrates that public Bt varieties will particularly improve technology access for resource-poor eggplant producers. The results suggest that public–private partnership can be beneficial for all parties involved. 相似文献
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《Food Policy》2014
There have been serious questions about whether lower-yielding farmers in developing countries, who are typically poor smallholders, benefit from genetically-modified crops like Bacillus thuringensis (Bt) corn. This article examines this issue by estimating the heterogeneous impacts of Bt corn adoption at different points of the yield distribution using farm-level survey data from the Philippines. A recently developed estimation technique called instrumental variable quantile regression (IVQR) is used to assess the heterogeneous yield effects of Bt corn adoption and at the same time address potential selection bias that usually plague impact assessment of agricultural technologies. We find that the positive yield impact of Bt corn in the Philippines tend to be more strongly felt by farmers at the lower end of the yield distribution. This result suggests that Bt corn could be a “pro-poor” technology since most of the lower-yielding farmers in the Philippines are poor smallholders with low incomes. 相似文献
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Shih–Chang Hung 《R&D Management》2002,32(3):179-190
In this paper, we examine the different evolutionary processes and outcomes of the hard disk drive and liquid crystal display industries in Taiwan. To this end, we make two general theoretical claims. First, that an appreciation of the globalization of technology is as important as national institutions in understanding industry development in catch–up economies such as Taiwan. Second, in addressing both industrial survival and failure, that national institutions can have either a positive or a negative impact on sectoral activities. Empirically, we show that, in Taiwan, rigid social institutions conflict with the hard disk drive technology. This conflict, in turn, produces obstacles to Taiwanese firms' search for new markets and skills in hard disk drives. On the other hand, Taiwan's institutional structures provide a source of technical efficiency and market opportunity for the emerging liquid crystal display trajectory. This, in turn, drives Taiwanese industry towards adopting new practices in the manufacture of liquid crystal displays. 相似文献
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甘氨酸的生产现状及发展趋势 总被引:2,自引:0,他引:2
我国是世界上甘氨酸生产国之一,目前中国甘氨酸的生产技术基本都采用已经被国外淘汰的氯乙酸氨解法工艺,虽然经过持续的改进,提高了反应的收率和产品的质量,但与国外技术相比较,仍有生产成本高,产品质量差的劣势,且只能生产工业级甘氨酸。文章分析了国内外甘氨酸的生产现状及市场情况,对制约我国甘氨酸发展的重要因素进行了讨论,建议重点发展以羟基乙腈为原料的直接Hydantion工艺,生产纯度在99.5%以上的甘氨酸产品,进一步拓展其在食品加工业中的应用。 相似文献
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戊烷的生产与市场分析 总被引:5,自引:0,他引:5
戊烷原料主要来源于炼油厂。戊烷产品用途广泛,可用作发泡剂、溶剂、化工原料等。目前国内高纯度异戊烷、正戊烷、环戊烷及混合戊烷发泡剂生产厂有36家,生产能力150kt/a左右.我国戊烷的年消费量近66kt,其中,EPS(发泡聚苯乙烯)戊烷发泡剂的消费量约占总消费量的45%;聚氨酯的发泡剂消费戊烷约占总消费量的50%;线性低密度聚乙烯戊烷载溶剂消费量约占总消费量的5%。国内戊烷供大于求,但高档产品供应不足。所以,“十五”期间新建装置一定要采用国内较为先进的工艺技术,采用较廉价的原料气,确保产品质量,最大限度的降低生产成本,同时加强市场开发,提高产品的市场竞争力。 相似文献
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Twenty‐five years of empirical research has failed to resolve a basic strategy question. Does strategic purity pay? Most theorists believe strategic purity—the extent to which a business pursues one type of generic strategy over another—contributes to better performance. By defining the strategy space consistent with the theory, and employing improved design and methods, our study of 2,351 businesses finds a significant relationship between strategic purity and performance. Purity does appear to pay. Some variations in strategic purity and performance relationship were observed across four major industry sectors: manufacturing, construction, retail, and business services. But in all instances pure strategies never did less well, and often did better than hybrid strategies. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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PTA生产工艺进展及工艺技术比较 总被引:2,自引:0,他引:2
李涛 《石油化工技术经济》2006,22(4):22-28
近年来全球对PTA的需求增长推动了PTA生产技术的不断发展,寻求更经济的生产工艺或高纯度对苯二甲酸制造技术已经成为研究的主要方向。文章综合介绍了目前国内外各类PTA的生产工艺及其技术发展状况,并对其中两种主要生产工艺就技术、产品质量、成本、投资费用及其发展前景进行了横向比较分析,展望了PTA新技术的发展方向。 相似文献