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41.
王晋春 《科技情报开发与经济》2003,13(9):153-154
冷战时期,非洲由于丰富的自然资源和重要的战略位置成为美苏两个超级大国争夺的重要区域。冷战结束以后,随着前苏联的解体,非洲的战略地位有所下降,美国对非洲的兴趣也日益减弱。但近几年来,美国对非洲的战略开始由冷变热。文章从政治地理角度对美国近年来对非石油战略的转变进行了分析。 相似文献
42.
张金菊 《科技情报开发与经济》2004,14(12):237-239
以棕榈油为原料合成增塑剂ZS-301,对棕榈油品质(以熔点计),氢氧化钠用量,氯化锌用量通过正交试验进行了确定。结果表明最佳条件为:选择熔点为48℃~51℃的棕榈油.氢氧化钠的用量16份,氯化锌用量15份(以棕榈油重量为100份计)。在最佳条件下所制得的10批样品均符合国外Pirelli公司同类产品的指标要求。 相似文献
43.
This paper assesses the information content of two survey indicators for consumption developments in the near future for eight European countries in the period 1985–1998. Empirical work on this topic typically focuses on consumer confidence, the perceptions of buyers of consumption goods. This paper examines whether perceptions of sellers of consumption goods, measured by retail trade surveys, may also improve short‐term monitoring of consumption. We find that both consumer confidence and retailer confidence embody valuable information, when analysed in isolation. For France, Italy and Spain we conclude that adding retail confidence does not improve the indicator model once consumer confidence has been included. For the UK the reverse case is obtained. For the remaining four countries we show that combining consumer sentiment and retail trade confidence into a composite indicator leads to optimal results. Our results suggest that incorporating information from retail trade surveys may offer significant benefits for the analysis of short‐term prospects of consumption. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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光周期对环青春期雄性根田鼠血浆睾酮及雌二醇含量的作用 总被引:1,自引:0,他引:1
根田鼠母体妊娠期(GP)及哺乳期(LP)光周期处理对环青春期雄体血浆睾酮的作用不显著(P>0.05);在断乳期(PP),光周期处理则存在极显著的作用(P<0.01)。在断乳前的GP及LP,母体长光照处理对子代雄体睾酮有抑制作用;而在PP,长光照处理对子代雄体睾酮则有显著促进作用。在LP,母体长光照处理对雄体血浆雄二醇有显著(P<0.05)促进作用。而在PP,长光周期处理对雄体血浆雌二醇则有抑制作用。 相似文献
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Obese postmenopausal female volunteers were given timed daily oral dosages of bromocriptine, and tested for reduction of body fat stores. This dopamine agonist has been shown to reset circadian rhythms that are altered in obese animals and to reduce body fat levels in several animal models. The participants were instructed not to alter their existing exercise and eating behavior during treatment. Skinfold measurements were taken on 33 subjects as indices of body fat. The measurements (e.g., suprailiac) were reduced after six weeks by about 25%, which represents a reduction of 11.7% of the total body fat. These dramatic decreases in body fat, which are equivalent to that produced by severe caloric restriction, were accompanied by more modest reductions of body weight (2.5%), indicating a possible conservation of protein that is usually lost as a consequence of such caloric restriction. The effects of bromocriptine treatment on body fat and hyperglycemia were also examined in non-insulin dependent diabetics being treated with oral hypoglycemics (7 subjects) or insulin (7 subjects). Total body fat was reduced by 10.7% and 5.1% in diabetics on oral hypoglycemics and insulin, respectively, without any significant reductions in body weight. Hyperglycemia was reduced in most of the 15 diabetic subjects treated leading to euglycemia and even cessation of hypoglycemic drugs in 3 of the 7 subjects during 4-8 weeks of bromocriptine treatment. These findings support the hypothesis that obesity and type II diabetes may be treated effectively with bromocriptine when administered at the proper times and dosages. 相似文献
48.
介绍了钢筋混凝土结构,钢结构和钢骨钢筋混凝土结构建筑在坂神地震中的破坏情况,了建筑结构的震害与建筑年代及建筑规范的变迁有关,高层建筑中的薄弱层和东同结构型式的转换层是震害的集中部位。 相似文献
49.
Short alanine peptides, containing 16 or 17 residues, appear to form alpha-helices in aqueous solution. But the main spectroscopic analyses used on helical peptides (circular dichroism and nuclear magnetic resonance) cannot distinguish between an alpha-helix (in which the ith residue is hydrogen-bonded to residue i + 4; ref. 9) and the next most common peptide helix, the 3(10)-helix10 (i-->i + 3 hydrogen-bonding). To address this problem we have designed single and doubly spin-labelled analogues of alanine-based peptides in which the nitroxide spin label forms an unbranched side chain extending from the sulphur atom of a cysteine residue. Here we report the circular dichroism, Fourier-transform infrared and electron-spin resonance spectra of these peptides under helix-forming conditions. The infrared absorbance gives an amide I' band with a frequency that is substantially different from that observed for alpha-helices. The electron-spin resonance spectra of doubly labelled helices show that the ranking of distances between side chains, around a single turn (residues 4-8), is inconsistent with an alpha-helical structure. Our experiments suggest that the more likely peptide geometry is a 3(10)-helix. 相似文献
50.
田径理论与技术教学CAI课件的研制与实践 总被引:1,自引:0,他引:1
田径教学是体育院、系教学的重点.当前,由于教学时数的减少,以往常规的教学手段已不能很好地完成教学任务,而利用建立在计算机技术基础之上的CAI则能很好地解决田径教学中存在的问题.对田径教学CAI课件的研制与实践过程进行了初步探讨. 相似文献