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1.
首先利用代数几何中的消除理论给出一类三波作用模型存在不变代数曲面的充分条件; 其次, 构造出该系统无穷多个Hamilton-Poisson结构, 即该系统是双Hamilton的; 最后, 利用R3中的Poincaré紧致化技巧完整刻画该系统在无穷远处的动力学行为.  相似文献   
2.
Henri Poincaré acquired a reputation in his lifetime for being difficult to read. It was said that he missed out important steps in his arguments, assumed the truth of claims that would be difficult if not impossible to prove, and in short that he lacked rigour. In the years after his death this view coalesced into an exaggerated claim that his work was simply too vague, and has become a cliché. This paper argues that Poincaré was far from indifferent to rigour, and that what characterises his work is an attempt to convey a particular sense of what it is to understand a topic. Throughout his working life Poincaré was concerned to promote the understanding of many domains of mathematics and physics. This is as apparent in his views about geometry, his conventionalism, and his theory of knowledge, as it is in his work on electricity and optics, on number theory, and function theory. It is one of the ways Poincaré discharged his responsibilities as a scientist, and that it accounts not only for a surprising degree of unity in his work but also gives it its distinctive character—at once profound and elusive.  相似文献   
3.
针对通过Ray-Knight紧化得到的强Markov过程,即正规链,说明了其停时性质.  相似文献   
4.
研究了一类Lévy噪声驱动的具有饱和发生率的随机SEIR传染病模型,证明了系统正解的存在唯一性,利用Lyapunov方法研究了该模型在无病平衡点和地方病平衡点附近解的渐近行为.  相似文献   
5.
《Journal of Natural History》2012,46(3-4):197-202
Thirteen Notostrix Keifer species are presently known, all from leaves of palm trees (Arecaceae) to which they seemingly cause no major damage. A new species of this genus, Notostrix macrothrix sp. nov., is morphologically described based on adult females and males collected from coconut, Cocos nucifera L. (Arecaceae), on La Reunión Island. A discussion about the presently known distribution of mites of this genus is also presented. http://www.zoobank.org/urn:lsid:zoobank.org:pub:14C65CB2-AF56-4D85-AD49-56FA11119EF5  相似文献   
6.
《Journal of Natural History》2012,46(33):3039-3058
During a soil zoology expedition to Sao Tomé Island, among other members of the soil fauna, earthworms were collected. During this collecting trip some 170 earthworm specimens belonging to 18 species were gathered of which two, Dichogaster (Diplothecodrilus) coeruleoviridis and Dichogaster (Diplothecodrilus) zicsii, proved to be new to science. In addition, a small sample from the same locality was also examined and Dichogaster (Dichogaster) thomeana Cognetti, 1910 Cognetti de Martiis, L. 1910. Lombrichi raccolti dal Cav. Leonardo Fea nelle Isole del Capo Verde e nel Golfo di Guinea.. Annali del Museo Civico di Storia Naturale di Genova, 4: 79118.  [Google Scholar] was removed from synonymy of Dichogaster (Dichogaster) greeffi Michaelsen, 1902 Michaelsen, W. 1902. Neue Oligochaeten und neue Fundorte alt‐bekannter.. Mitteilungen aus dem Naturhistorischen Museum in Hamburg, 19: 353.  [Google Scholar].  相似文献   
7.
Summary

Records of ten species of Sosylus collected in Nigeria are given, with details of distribution, host trees and platypodid associates. The Sosylus fauna of Nigeria appears to lie between that of Ghana and the Congo in species composition. Comment is made on the close association that some Sosylus species have with their platypodid hosts.  相似文献   
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9.
加速器驱动的次临界系统(Accelerator Driven Sub-critical System,ADS)是加速器技术和核反应堆技术的结合,其主要目的是应对当今快速增长的放射性核废料处理需求.本文初步探讨了在ADS系统中利用232Th生产可裂变核233U的可能性,估计了所需加速器的性能及其生产233U的产率和效率.我们建议用Be做中子慢化剂和增殖剂,将反应堆的中子能量大部分控制在1keV–1MeV,从而最大限度地降低232U的含量.也可进一步利用重水做慢化剂高233U的纯度.所生产的233U既可经分离取后在热堆中燃烧,也可直接用于钍基熔盐堆的初始装料,发挥233U优异的热中子性能.我们的结果表明,在技术上和经济上利用ADS生产233U很可能是可行的.我们的结果还表明,如果这一ADS系统主要目的是生产233U,所选择的次临界堆的最佳是快中子堆,而不是慢中子堆或快慢结合堆.最后我们建议对钍基核反应堆、233U的取分离工和辐射防护等方面的课开展进一步深入研究.  相似文献   
10.
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