共查询到20条相似文献,搜索用时 49 毫秒
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鲜果蔬保鲜包装中包装膜的阻隔性能对于果蔬的保鲜具有重要影响,本研究利用不同种类的凝固浴制备LiCl/DMAc工艺再生纤维素包装膜,并考察了甲醇、乙醇、异丙醇、LiC l/DMAc和去离子水对纤维素包装膜的断面结构、表面结构、透氧和透湿性能以及机械性能的影响。结果表明,使用醇类凝固浴制备的纤维素包装膜的断面呈松散结构,尤其是以乙醇凝固浴制备的包装膜出现了指状孔;包装膜的透氧性能明显提高,乙醇凝固浴制备的纤维素包装膜的透氧系数为15%LiCl/DMAc凝固浴制备的纤维素包装膜的50倍,并且其机械性能达到12.7Mpa,可以满足日常包装性能要求。 相似文献
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季春晓 《石油化工技术经济》2009,25(6):28-33
介绍了硫氰酸钠湿法研制扁平腈纶的原理,探讨了原液性能、凝固浴成形条件、定型条件、油剂选择对扁平腈纶性能指标的影响。结果表明:控制原液性能指标在合适的范围内,采取弱化定型工艺,提高凝固浴温度,降低凝固浴浓度,减少凝固浴流量的工艺条件有利于纤维成形状态趋向于矩形,提高纤维的扁平度;选择主要成分为烷基酰胺阳离子乳化剂和烷基胺阳离子高分子醚的复配油剂,可使扁平纤维既有良好的蓬松性、滑爽性,且抗静电效果良好。 相似文献
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本文以均衡凝固理论为基础,指出在指定高牌号厚断面灰铸铁平板件的工艺时,应根据铸件本身结构均匀,凝固规律易于掌握的特点,充分利用铸件本身的自补缩能力。 相似文献
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论中国元素在高级时装中的应用 总被引:1,自引:1,他引:0
随着奥运会和世博会的成功举办,中国元素在设计界又再度成为热点。本文将适用于高级时装的中国元素归纳分类为质(指的是中国概念的材质、材料)、形(指的是具有代表性的从形式上表达中国概念的外观元素,形状、图形)、色(指的是具有代表性的中国色)、艺(指的是中国的传统手工技艺)四大类,对其设计手法逐一研究分析,并总结其应用规律。 相似文献
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历经30年的发展,经济园区成为我国的投资热土,在经济园区发展日趋成熟的过程中也出现了各种问题,造成对自身发展的束缚和周围环境的影响。本文阐述了经济园区的发展历程和模式,分析问题产生的原因,以及对企业竞争和可持续发展带来的不利影响,并结合我国经济园区的发展特点,提出政府应不断完善创新体制,加强规范管理的政策建议。 相似文献
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互联网时代商业模式的创新的研究已成为近几年财务金融、市场营销、公司治理等方面热点,研究主要体现在商业模式创新的种类与对财务的绩效影响方面,这些问题的研究仍有待深入.本文认为,互联网时代商业模式的创新需要结合互联网时代的特点与商业模式的要素进行分析.电商平台在互联网时代如何防范创新的商业模式对财务绩效带来的风险,如何应对... 相似文献
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Capacity reservation under spot market price uncertainty 总被引:1,自引:0,他引:1
Karl InderfurthPeter Kelle 《International Journal of Production Economics》2011,133(1):272-279
Capacity reservation contracts and spot markets are two alternative purchasing practices. We focus on the cost-effective management of the combined use of these two procurement sources. Due to the variability of the spot market prices and demand uncertainty, the flexibility of combined sourcing can be advantageous. Spot market purchasing is a benefit in case of low spot market prices or insufficient reserved capacity, and the capacity reservation contract is an operational risk hedging for high spot market price incidents. The structure of the optimal combined purchasing policy is complex. In this paper we consider a simple and easy-to-implement capacity reservation—base stock policy and compare it to single sourcing options. We examine the joint effect of demand and spot market price uncertainty. Our analysis shows that in the case of large spot market price variability the combined sourcing is superior over spot market sourcing even in the case of low average spot price. The combined sourcing is also superior over long-term sourcing even in the case of high average spot price if there is large spot market price variability. Analytical and simulation results are presented to show the effect of the different price, cost, and uncertainty parameters on the optimal capacity reservation—base stock policy and on the expected percentage gain over single sourcing. 相似文献
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Opportunity Cost Pass‐Through from Fossil Fuel Market Prices to Procurement Costs of the U.S. Power Producers
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This paper investigates the transmission of fossil fuel commodity spot market price changes to procurement costs of U.S. power producers. We measure and compare the speed and magnitude with which spot prices predict procurement costs using restricted access fuel price data. Natural gas spot prices are quickly reflected in procurement costs. Coal spot prices offer very little predictive power to coal procurement costs. Although not causal, the empirical results also show differences across regulatory status. These findings may have implications for the electricity market deregulation literature that creates marginal cost curves as a competitive benchmark. 相似文献
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The Electricity Contract Market in England and Wales 总被引:24,自引:0,他引:24
Richard Green 《The Journal of industrial economics》1999,47(1):107-124
In England and Wales, wholesale electricity is sold in a spot market partly covered by long-term contracts which hedge the spot price. Two dominant conventional generators can raise spot prices well above marginal costs, and this is profitable in the absence of contracts. If fully hedged, however, the generators lose their incentive to raise prices above marginal costs. Competition in the contract market could lead the generators to sell contracts for much of their output. Since privatisation the generators have indeed covered most of their sales in the contract market. 相似文献