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本文介绍了当前数据库技术的发展现状和流行的主流数据库,对数据库发展的新技术和未来的发展趋势也作了浅述. 相似文献
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钛酸钾晶须通常是直径和长度在微米量级的无机晶须 ,可用K2 O·nTiO2 表示其组成 ,n =1,2 ,4 ,6 ,8,[1] .六钛酸钾晶须具有耐高温、耐腐蚀、纤维拉伸强度高、导热系数小、红外反射率高 ,硬度低的特点 .在民用及工业方面有很多应用 .如催化剂载体、离子吸附交换材料、高温过滤器、绝热材料、耐摩擦材料等[2~ 5] .钛酸钾纳米线的合成尚未见报道 .我们在用电弧产生的N2 等离子体热解焦油时 ,生成了一种直径 9~ 2 0nm长约几百纳米线 .X射线能谱定量分析表明这种纳米线化学组成为K2 Ti8O15,是一种新的非化学计量化合物 .试验装… 相似文献
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Scott Gaynor Dorota Greszta Daniela Mardare Mircea Teodorescu Krzysztof Matyjaszewski 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1561-1578
Various methods which lead to the control of molecular weight and polydispersities, and which allow for the preparation of block copolymers by radical polymerization are discussed. Thermal polymerizationof styrenes in the presence of stable radicals, polymerization of vinyl acetate and methyl methacrylate in the presence of chromium complexed by macrocyclic ligands polymerization of vinyl acetate initiated by organoaluminum compounds complexed by dipyridyl and activated by stable radicals, as well as in the presence of phosphites, are described in detail. 相似文献
26.
Jeffrey James 《Telematics and Informatics》2012,29(1):2-10
Often, an answer to the question posed in the title is provided for either mobile phones or the Internet but not both at once. In this paper by contrast I require that successful countries do well on both forms of technology, over the period from 2000 to 2006. Using two measures for both mobile phones and the Internet, countries were ranked in four tables, which served as the basis on which the major conclusions were drawn. I find that Jamaica performs much better than any other low or low-middle income country, though there is a group of four other countries in a clear secondary position. My explanations of particular outcomes were often limited by the unavailability of good country-case material (though there is some). 相似文献
27.
The influence of early adopters on potential adopters’ decisions of whether or not to adopt a product is known to be critical. In this paper, we examine the factors that influence the adoption behavior of smartphone early adopters by looking at smartphone adoption behavior of college students, because a large portion of the early adopters of smartphones are college students. Our focus is on the effect of normative peer influence on a college student’s smartphone adoption. We also examine the influence of other factors such as self-innovativeness, self-efficacy, the decision maker’s attitudes towards a product, financial burden of using the product, familial influence, and other demographic factors (e.g., age and gender). College students’ adoption behavior is studied using logit and probit choice models developed based on random utility theory. The discrete choice models are empirically estimated using survey data. We find important influence of friends, financial burden, and other family members on the smartphone adoption of college students who adopted smartphones earlier than other students. 相似文献
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Dušan Barać Vanjica Ratković-Živanović Marijana Despotović-Zrakić Aleksandra Labus Zorica Bogdanović 《Telematics and Informatics》2017,34(1):20-29
This paper examines the possibilities of enhancing relationship management between public service broadcasters and their stakeholders by harnessing the potential of newest e-business technologies and concepts, such as: social media, digital and interactive TV, and mobile computing. In order to facilitate adoption of relationship management strategy, a framework for leveraging relationship management is proposed. Evaluation was performed within the e-business system of a public broadcaster. This empirical study explored the readiness and expected benefits of relationship management implementation. The research results have indicated that a public broadcaster could achieve a higher level of social responsibility, improve business sustainability, and empower communication and collaboration with all the stakeholders by using emerging technologies for relationship management activities. 相似文献
29.
A. B. A. Elgazzar A. M. Gafaar H. N. Hafez A. S. Aly 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1859-1883
Pyridopyrimidine derivatives 2 reacted with hydrazonoylchloride derivatives and yielded triazolopyridopyrimidines 6a–f. Compound 4b reacted with aliphatic acids and afforded triazolo-pyridopyrimidines 7a,b, and the reaction with carbon disulfide afforded 10-mercapto-triazolopyridopyrimidine (10). Moreover, the reaction of 4b with β -ketoesters afforded 10-pyrazolyl-pyridopyrimidines derivatives 11, 13, 14, and 15. Compound 4b reacted with nitrous acid to give tetrazolopyridopyrimidine 16, which reduced to 10-amino-derivative 17. On the other hand, the reaction of 4b with aromatic aldehydes afforded arylidines derivatives 18a–c, which were later cyclized to triazolo-pyridopyrimidines deivatives 19a–c. Finally, 4b reacted with α-haloketones to give triazines derivativrs 20, with new ring systems. 相似文献
30.
You Wei 《Journal of Dispersion Science and Technology》2013,34(12):1785-1794