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991.
Using a mixed method approach of questionnaires, observations and field notes, the authors have studied a number of settings during the past two years which have focussed on the development of ICT capability through play. Some of these have involved children identified as disaffected or disadvantaged, whilst others have involved initial teacher education students. In this paper, we consider some of the results obtained from the most recent of these settings, relate these to those obtained from the other settings, and explore further a number of inter-related issues which have arisen from the analysis. We particularly focus on the effect of learners’ self-esteem and self-efficacy; the influence of gender-related characteristics; the role of interaction between learners during activity; and the value of reflection. 相似文献
992.
Anthraquinone [1, 2-C] methylisoxazole is synthesized from 2-ethylanthraquinone through nitration and treating with oleum. The different methods of 2-ethylanthraquinone nitrated were discussed. The optimum conditions were determined. The structure of the product was confirmed by MS and 1H NMR. 相似文献
993.
分析了环氧乙烷,乙二醇装置工艺系统中有机酸生成的原因.指出在银催化剂作用下,乙烯氧化过程有机酸生成主要成分是甲酸和乙酸,银催化剂不是影响氧化反应器出口醛含量的主要因素;杂质、温度等对反应器出口气中的醛含量有重要影响,也直接影响到装置前系统的有机酸含量;乙二醇后系统中有机酸的增加仅取决于两级吸收及解析工艺的稳定操作。 相似文献
994.
After a series of earthquakes in 1999, Turkish Red Crescent (TRC) has engaged in a restructuring for all of its activities, including the blood services. Our study on the blood management system had been started as part of this initiative to restructure the blood services and improve both their effectiveness and efficiency. In the current system of TRC, not much consideration has been given to how the locational decisions affect the performance of blood centers, stations and mobile units. In recent years, however, there has been much discussion regarding the regionalization of the blood management system in Turkey. In this study, we develop several mathematical models to solve the location–allocation decision problems in regionalization of blood services. We report our computational results, obtained by using real data, for TRC blood services. 相似文献
995.
本文介绍一种基于TCP/1P协议的新型水力物理模型试验测控系统,该系统将目前最先进、最流行的工业以太网技术应用到物理模型试验研究的测控系统中,实现多点水位、流速和流量等水力学重要参数的实时采集、处理、储存、显示及打印,并具有在线查询及数据分析功能。 相似文献
996.
零售业是生活中常见的行业,在零售业中引入了电子收款机系统(Point of Sells,POS)即进销存管理系统,是商店经营中的最热门的话题之一。这种进销存管理系统一般是现在比较常见的客户端/服务器模式也即C/S模式。文章介绍了采用INSPRISE公司的DELPHI7.0开发工具结合SQL SERVER2000数据库服务器。首先在短时间内建立系统应用原型,然后,对初始原型系统进行需求更迭,不断修正和改进,直到形成用户满意的可行系统。 相似文献
997.
Johanna Bakker Colin F. Timberlake 《Journal of the science of food and agriculture》1985,36(12):1315-1324
The distribution of anthocyanins in methanolic skin extracts of 16 grape cultivars used for port wine production and grown at five sites in the Douro Valley in Northern Portugal has been assessed by high performance liquid chromatography. Results are confined to the seven most readily separated and identified anthocyanins and are expressed as percentages of their total (88–99% of the total integrated area). Anthocyanins based on malvidin (Mv) predominated. Of these, Mv 3-glucoside was the major pigment (33–60%), being exceeded by Mv 3-p-coumarylglucoside (2–51%) in only two cultivars; Mv 3-acetylglucoside (1–15%) was consistently the lowest. Peonidin 3-glucoside (1–27%) was prominent in four cultivars, but delphinidin 3-glucoside (1–11%), petunidin 3-glucoside (2–11%) and cyanidin 3-glucoside (trace-6%) were of low proportions throughout. The ratio Mv 3-acetylglucoside/total Mv glucosides appeared characteristic of cultivar, independent of site, and a useful aid to identification of grape cultivars. The coloured pulp of some cultivars contained peonidin 3-glucoside as a major component, present in greater proportions than in the skin; the percentage of Mv 3-p-coumarylglucoside was lower in pulp than in skin. The identities of six of the seven anthocyanins were confirmed by fast atom bombardment mass spectrometry and the structures of the Mv derivatives were determined by nuclear magnetic resonance. The formation of formyl and acetyl anthocyanin artefacts is described. 相似文献
998.
高敬 《稀有金属与硬质合金》1998,(1)
对奥地利普兰西公司作了简要介绍,并将我国的钨、钼产品标准和普兰百公司的钨、钼产品、规格进行了对比。根据差距提出了我国钨、钼产品今后的发展方向。 相似文献
999.
The kinetics of disproportionation of methylamine to dimethylamine and ammonia in the presence of hydrogen have been investigated over a silica-supported palladium catalyst. At a fixed partial pressure of methylamine, the reaction rate generally increases with decreasing hydrogen partial pressure, approaching a limiting or maximum value at sufficiently low pressures of hydrogen. The existence of a maximum is supported by the observation that the presence of some hydrogen appears to be necessary for the reaction to proceed at a conveniently measurable rate. At a fixed hydrogen partial pressure, the reaction rate increases with increasing methylamine partial pressure. When the methylamine partial pressure is sufficiently low or the hydrogen partial pressure is sufficiently high, the reaction order with respect to methylamine can be somewhat higher than one. At such conditions, a mechanism involving a bimolecular reaction between two partially dehydrogenated methylamine molecules on the surface appears to make a significant contribution to the overall catalytic reaction. 相似文献
1000.
A method has been developed, using a silicon-rubber-based sealant, which allows 2–3-mm-thick specimens to be maintained in a protected fluid environment for a number of months, without risk of dehydration. Following this, the specimen can be retrieved, stained, embedded and sectioned further. For example, 2-mm-thick sections of fixed unstained bone are easily examined by means of epi-illuminated polarized light and fluorescence microscopies using either conventional or confocal optics. The method could easily be extended to other tissues, for example brain tissue. 相似文献