共查询到20条相似文献,搜索用时 31 毫秒
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在艺术大师及其流派层出不穷、交相辉映的20世纪初,回顾莫迪里阿尼那一段历史,有着不容忽略的意义.他是一个真正的独行者,游离于所有时髦的艺术流派之外,他独特的人像创作与他对美学独到的理念遥相呼应,确立并巩固了他在现代艺术史上的地位.本文介绍了他不同时期的经历对他的艺术作品的影响,以及他短暂却又卓越的艺术生涯. 相似文献
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从今年4月1日起,国家对斜交轮胎生产企业的消费税征缴从原来的10%调整下降到3%.缴征税的调整,意味着轮胎企业缴税的负担轻了.从某种意义上来讲,有利于经营效益的提高、再生产资金的增加和积累、提高和改善职工的福利,会有更多的资金投入产品的研发和设备的更新改造,这是一个利好消息.但是,笔者认为,这是机遇和挑战并存的非常时期! 相似文献
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The strength of the randomized trial to yield conclusions not dependent on assumptions applies only in an ideal setting. In the real world various complications such as loss-to-follow-up, missing outcomes, noncompliance and nonrandom selection into a trial force a reliance on assumptions. To handle real world complications, it is desirable to make as few and as reasonable assumptions as possible. This article reviews four techniques for using a few reasonable assumptions to design or analyse randomized trials in the presence of specific real world complications: 1) a double sampling design for survival data to avoid strong assumptions about informative censoring, 2) sensitivity analysis for partially missing binary outcomes that uses the randomization to reduce the number of parameters specified by the investigator, 3) an estimate of the effect of treatment received in the presence of all-or-none compliance that requires reasonable assumptions, and 4) statistics for binary outcomes that avoid some assumptions for generalizing results to a target population. 相似文献
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N. Dudai A. Poljakoff-Mayber A. M. Mayer E. Putievsky H. R. Lerner 《Journal of chemical ecology》1999,25(5):1079-1089
Essential oils were extracted from 32 aromatic plants and evaluated for allelopathic properties. The major components of the oils were identified by gas chromatography and GC-MS. Extracts from Origanum syriacum, Micromeria fruticosa, and Cymbopogon citratus were selected for further study. The germination of several species, including wheat, was strongly inhibited by essential oils when applied at 20–80 ppm. Essential oils mixed with the top 0.5 cm of soil inhibited germination of wheat and Amaranthus seeds. This effect depended on the type of soil. The possible use of essential oils as herbicides is discussed. 相似文献
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德育工作就是通过引导人们对自己行为的自觉性认识来培养其自律意识,将社会的思想道德要求转化为人们的内在需要,形成正确的价值观念和道德品质,进而规范自己的行为.但事实上,德育工作要取得成效,仅靠人们的自律是不够的,还必须依靠管理、法律等他律手段.
高尚思想道德的培养,不仅要靠耐心细致的思想教育,还要靠科学规范的严格管理.二者相辅相成,缺一不可.把社会主义的思想道德融于科学有效的管理之中,把自律和他律、内在约束和外在约束、教育和管理、提倡和禁止有机结合起来,这才是提高德育工作实效和水平的重要途径. 相似文献
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对目前国内外连续重整技术的发展趋势以及技术进步所面临的问题进行了综述,并介绍了连续重整工艺技术和催化剂的最新进展。 相似文献
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揭示了连续重整的反应温度、压力、空速、氢油比、催化剂循环速率的相互关系,以及催化剂、原料和产品辛烷值对这些参数的影响。通过对比现有连续重整装置的设计参数及实际运行状况,充分考虑连续重整工艺和催化剂的技术进步,对新建连续重整装置的设计参数进行了探讨。 相似文献
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McGarrigle EM Myers EL Illa O Shaw MA Riches SL Aggarwal VK 《Chemical reviews》2007,107(12):5841-5883
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Micah J. Green Author Vitae Natnael Behabtu Author Vitae Matteo Pasquali Author Vitae W. Wade Adams Author Vitae 《Polymer》2009,50(21):4979-81
In this review, we show that the structure and behavior of single-walled nanotubes (SWNTs) are essentially polymeric; in fact, many have referred to SWNTs as “the ultimate polymer”. The classification of SWNTS as polymers is explored by comparing the structure, properties, phase behavior, rheology, processing, and applications of SWNTs with those of rigid-rod polymers. Special attention is given to research efforts focusing on the use of SWNTs as molecular composites (also termed nanocomposites) with SWNTs as the filler and flexible polymer chains as the host. This perspective of “SWNTs as polymers” allows the methods, applications, and theoretical framework of polymer science to be appropriated and applied to nanotubes. 相似文献
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David C. Sherrington 《Polymer International》1980,12(2):70-74
Polymers have been widely used as catalysts or catalyst supports and the various applications can be categorised conveniently into four groups (a) catalysis by soluble linear polymers, (b) catalysis by ion exchange resins, (c) polymer-supported ‘homogeneous’ metal complex catalysts and (d) polymer-supported phase transfer catalysts. A brief review of each of these is given, with citation of some of the more recent and important examples which illustrate some of the basic principles involved. 相似文献
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Phosphates as Catalysts 总被引:1,自引:0,他引:1
J. B. Moffat 《Catalysis Reviews》1978,18(2):199-258
Although carbon is often considered as the dominant element in terms of covalent bond formation, phosphorus can undoubtedly be considered a s a serious competitor for this position [1]. Further, at least in principle, phosphorus is potentially capable of forming more compounds than carbon. For a variety of reasons, both academic and practical, interest in phosphorus compounds has increased markedly over the last decade. It is not unexpected, then, to find that the use of compounds of phosphorus as catalysts has also accelerated. Unfortunately, a s is often the case in science, the practice outruns the theory with such catalysts, but industrialists and academicians alike have recently displayed an enhanced interest in the mechanisms of catalytic activity on such catalysts. 相似文献
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《国际聚合物材料杂志》2012,61(1-2):5-42
Abstract The chemistry and technology of polymers has developed rapidly during the last three decades; it concerns itself with materials consisting essentially of the elements C, H, N, and O, and being therefore conventionally classified as organic polymers. However, in many instances other elements such as B, Si, P, S, F, and CI are present in certain proportions and have a more or less important influence on the ultimate properties of the products. Together with the large family of metallic compounds and ceramic systems, organic polymers represent useful and increasingly important engineering materials in the construction of buildings, vehicles, engines, applicanes, textiles, packaging, printing and writing materials, plastics, rubber goods and household articles of all kinds. 相似文献
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Silicon has the ability to form polymeric chains, commonly linear chains of dimethylsiloxane, although other organic groups can be substituted for methyl. In addition, the properties of the resultant silicone polymers can vary with composition and curing procedure. This leads to a wide range of materials known as the silicones. This group of polymers, which have excellent biocompatibility, have been utilised to develop and manufacture a wide range of biomedical products. These range from simple tubing to complex implants, for example those used to replace diseased finger joints. The versatility of these materials has led to silicone products being employed in almost every medical speciality. 相似文献