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1,3,5-三甲基-1,1,3,5,5-五苯基三硅氧烷(1)含有较多苯基,其沸点较高(225℃/0.2mm),饱和蒸汽压低,热稳定性和抗氧化性能良好,可作为理想的高真空扩散泵油. 相似文献
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本文将2-调和映照从黎曼流形推广到V-流形,获得了2-调和映照的第一变分和第二变分,得到了2-调和映照成为调和映照的一些充分条件,讨论了V-流形上2-调和映照的复合映照。 相似文献
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1 INTRODUCTION The enantiomers separated by a co- crystallization method using an appropriate chiral as separating reagent has attracted many attentions in the past years[1]. Recently we are interested in enantiomeric discrimination by chiral amino acid. When racemic D,L-tartaric acid was tried to be separated by the L-glutamine in a hot aqueous solution, the well shaped crystals were obtained. The determination of melting point (220℃) and density (1.66 g穋m-3) showed it is… 相似文献
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本实验测量了C12(d,p)C13及Ca40(d,p)Ca41基态反应质子群的角分布和微分截面。氘核能量为13.3MeV,对C12和Ca40的反应,其测量角度范围分别为3°—167°和10°—164°,每隔2.5°或5°测量一点,其主要结果如下:(1)对于这两群质子,在主削裂峯附近的实验点和用简单Butler理论算得的理论角分布曲线都符合得相当好;理论计算数据对实验数据在主峯处归一;由此而定得的核能级参数与前人所得到的是一致的。(2)大角度区的实验截面数值没有减小到象Butler理论所要求的那样小,并有非常明显的次极大出现,其位置与Butler理论所预言的不一致;这些特点可以用扭曲波理论来解释,非氘核削裂机制也可能有部分贡献。(3)在C12(d,p)C13反应中,前角度区的截面有很大下降,而后角区则有明显的增加,这些现象都和Butler理论不一致;然而,这也可以用扭曲波来解释。(4)用主峯处的截面和Butler理论算得的基态的约化宽度,对C12(d,p)C13和Ca40(d,p)Ca41反应分别为r2=0.17和0.041;用扭曲波理论计算时,则得到较大的r2值,后者更接近于单粒子模型所预言的数值,基于上面这些事实,对本实验的数据使用扭曲波理论来进行分析似乎是值得的。 相似文献
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This article introduces an analytical framework for two small-world network models and studies the delay of targeted social search by considering messages traveling between source and target individuals in these networks. In particular, by considering graphs constructed on different network domains, such as rectangular, circular, and spherical network domains, analytical solutions for the average social search delay and the delay distribution are obtained as functions of source–target separation, distribution of the number of long-range connections and geometrical properties of network domains. Derived analytical formulas are first verified by agent-based simulations and then compared with empirical observations in small-world experiments. These formulas indicate that individuals tend to communicate with one another only through their short-range contacts and the average social search delay rises linearly, when the separation between the source and target is small. As this separation increases long-range connections are more commonly used, and the average social search delay rapidly saturates to a constant value and stays almost the same for all large values of the separation. These results do not require the dimensionality of the social space to be identical to the decay exponent of long-range social connections and are qualitatively consistent with experimental observations made by Travers and Milgram in 1969 as well as by others. Moreover, analytical distributions for the delay of social search predicted by the models introduced in this article are also compared with corresponding empirical distributions, and good statistical matches between them are observed. Other somewhat surprising conclusions of the article are that hubs have limited effect in reducing the delay of social search and variation in node degree distribution adversely affects this delay. 相似文献