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排序方式: 共有314条查询结果,搜索用时 312 毫秒
71.
对卞杨长输管线污垢类型进行分析,并从化学清洗方法的角度对清洗剂的组成作了讨论。室内实验结果表明:低浓度无机酸—盐酸对污垢有较好的清洗能力;酸液浓度,清洗温度等对清洗有很大影响;清洗剂中氧化剂的添加可有效控制有害气体—硫化氢的生成。 相似文献
72.
This research incorporates the development and adoption of an induced technology under uncertainty into a conceptual dynamic model to more broadly examine efficient policies for mitigating invasive species infestations. We find that under optimal policy, marginal costs of adopting conventional control measures are equal to the sum of the marginal benefits from development and adoption of new technology, as well as the use of conventional control measures. This result implies that a resource allocation designed for controlling invasive species is not adequate when an induced technology is not considered. Our results also reveal that the shadow values associated with the probabilities of developing and then adopting an induced technology increase as the shadow values associated with the stock of an invasive species population increase. 相似文献
73.
采用L9(34)正交实验方法研究马铃薯化学去皮与护色的最佳工艺:去皮是在NaOH浓度5%、碱液温度100℃条件下,根据块茎大小灵活掌握浸泡时间;护色采用1.0%Vc、1.5%柠檬酸和0.1%氯化钙混合液处理20分钟。 相似文献
74.
若定义了标准化学势μ—,其他标准热力学量可从μ—和热力学函数之间的关系通过数学计算得到.本文定义了凝聚相和溶液中物质B的标准化学势,根据标准化学势选取了相应的标准态,并讨论了活度、活度系数以及渗透系数等,对方程中有关符号和术语也予以详细说明 相似文献
75.
《Journal of gay & lesbian social services》2013,25(2-3):105-118
Summary This article focuses on lesbians in later midlife who are in recovery (for at least six months) from chemical dependency and on the ways the traumatic effects of their chemical dependency affect and influence the issues they face, the decisions they make, the actions they take, and, most especially, the relationships they have with both self and others. Although earlier midlife (from 40 to 50) is an important time, we will focus on the later years (from 50 to 60) because they seem to comprise the critical decade, the time when “old selves are lost and new ones come into being” (Stein, 1983, p. 3). 相似文献
76.
高师本科化学教育专业课程改革研究 总被引:1,自引:0,他引:1
Shi Jun-ling 《华中师范大学研究生学报》2008,(3)
随着我国基础教育课程改革的不断深入,对教师教育改革提出了更高的要求。本文通过对武汉市十所中学化学教师综合素质的现状调查,分析了目前高师本科化学教育专业课程设置存在的问题,并提出和构建了新的课程体系,以期为高师化学教育专业课程改革提供提论和实践参考。 相似文献
77.
利用干纺丝工艺,采用溶胶 凝胶法结合化学模板法制备了Ce0.5Zr0.5O2纳米多孔纤维,并在此基础上采用传统抄纸法制备了Ce0.5Zr0.5O2纤维纸。通过引入SiO2、TiO2和Al2O作为支撑体,利用XRD、低温N2吸附、拉曼光谱等手段分析了Ce0.5Zr0.5O2纳米多孔结构性能的变化。在空气条件下通过循环热失重分析法测定了材料在300~800 ℃温度范围内的氧储存能力,Ce0.5Zr0.5O2纳米多孔纤维的氧储存能力受到包括材料的比表面积、结晶程度以及支撑体性质等多方面因素的影响。 相似文献
78.
79.
化学反应工程教学体会 总被引:2,自引:0,他引:2
文章以提高化学反应工程教学质量为目标,介绍了一些提高化学反应工程教学效果的个人体会,希望能为化学反应工程教学改革提供参考。 相似文献
80.
Chemicals indisputably contribute greatly to the well-being of modern societies. Apart from such benefits, however, chemicals often pose serious threats to human health and the environment when improperly handled. Therefore, the European Commission has proposed a regulatory framework for the Registration, Evaluation and Authorization of Chemicals (REACH) that requires companies using chemicals to gather pertinent information on the properties of these substances. In this article, we argue that the crucial aspect of this information management may be the honesty and accuracy of the transfer of relevant knowledge from the producer of a chemical to its user. This may be particularly true if the application of potentially hazardous chemicals is not part of the user's core competency. Against this background, we maintain that the traditional sales concept provides no incentives for transferring this knowledge. The reason is that increased user knowledge of a chemical's properties may raise the efficiency of its application. That is, excessive and unnecessary usage will be eliminated. This, in turn, would lower the amount of chemicals sold and in competitive markets directly decrease profits of the producer. Through the introduction of chemical leasing business models, we attempt to present a strategy to overcome the incentive structure of classical sales models, which is counterproductive for the transfer of knowledge. By introducing two models (a Model A that differs least and a Model B that differs most from traditional sales concepts), we demonstrate that chemical leasing business models are capable of accomplishing the goal of Registration, Evaluation and Authorization of Chemicals: to effectively manage the risk of chemicals by reducing the total quantity of chemicals used, either by a transfer of applicable knowledge from the lessor to the lessee (Model A) or by efficient application of the chemical by the lessor him/herself (Model B). 相似文献