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821.
822.
利用平面分层介质中电磁场Green函数的解析形式,求解位于复杂分层介质结构中的原子电四极自发辐射速率.考虑一特例,结果表明与特殊介质结构中由电磁场模式求解的电四极子衰减速率相同. 相似文献
823.
张贺 《重庆三峡学院学报》2012,28(1):115-118
检察权监督制约机制分为内部监督制约机制和外部监督制约机制,我国现行内部监督制约机制发挥了巨大作用,但也存在着诸多不足。因此,构建合理的检察权内部监督制约机制,在司法实践中强化其内部监督制约机制作用十分必要。 相似文献
824.
Beta integrals for several non-integer values of the exponents were calculated by Leonhard Euler in 1730, when he was trying
to find the general term for the factorial function by means of an algebraic expression. Nevertheless, 70 years before, Pietro
Mengoli (1626–1686) had computed such integrals for natural and half-integer exponents in his Geometriae Speciosae Elementa (1659) and Circolo(1672) and displayed the results in triangular tables. In particular, his new arithmetic–algebraic method allowed him to compute
the quadrature of the circle. The aim of this article is to show how Mengoli calculated the values of these integrals as well
as how he analysed the relation between these values and the exponents inside the integrals. This analysis provides new insights
into Mengoli’s view of his algorithmic computation of quadratures. 相似文献
825.
A larger-scale Zr70Pd30 alloy system has been simulated using molecular dynamics (MD) to investigate structure evolution in Zr70Pd30 metallic glass. The simulated pair distribution function of Zr70Pd30 metallic glass agrees well with the experimental results. Voronoi polyhedron analysis indicates that the icosahedra are not
randomly distributed in space, but form characteristic intercrossed icosahedral clusters with medium-range order. Intercrossed
icosahedral clusters are the dominant local configurations in Zr70Pd30 metallic glass and probably cause the quasicrystalline phase discovered in Zr70Pd30 metallic glass. 相似文献
826.
Surface pollen assemblages of human-disturbed vegetation and their relationship with vegetation and climate in Northeast China 总被引:1,自引:0,他引:1
ManYue Li YueCong Li QingHai Xu RuiMing Pang Wei Ding ShengRui Zhang ZhiGuo He 《科学通报(英文版)》2012,57(5):535-547
Pollen assemblages of 53 surface pollen samples from farmlands and wastelands in Northeast China were analyzed. Tree pollen percentages were usually higher than 30%, with Pinus (26.9%), Quercus (0.9%), Betula (0.9%) and Populus (0.7%) as the major types, and herb pollen percentages were usually higher than 50%, with weedy Poaceae (8.7%), Chenopodiaceae (7.1%), Artemisia (1.9%) and Compositae (3.5%) as the major taxa. Thus, the pollen assemblages were consistent with the regional vegetation compositions. However, there were differences in pollen assemblages among regions, especially among different geomorphological units. For example, in the mountains, there were more types of tree pollen and higher total percentages (average 42%) than in other areas, while cereal pollen percentages were lowest (11.2%). In the hills and high plains, herbs made up more than 60% of the pollens, with cereals (average 53.6%) the dominant type. In the low plains, pollen types were similar to those in the hills and high plains, but total pollen concentrations and the proportion of Concentricystes were much higher, while cereal pollen percentages were slightly lower (average 41.6%). Pollen assemblages in different land use types also differed. For example, in farmland, cereal pollen percentages were more than 40% and Chenopodiaceae was usually less than 2.5%, while in wasteland, weedy Poaceae was usually less than 10% and Chenopodiaceae was usually higher than 25%. Total pollen concentrations in farmland (average 3909 grains/g) were much lower than in wasteland (average 15074 grains/g). Redundancy analysis revealed that pollen assemblages were significantly negatively correlated with mean annual temperature (-0.73) and July mean temperature (-0.81) and significantly positively correlated with mean annual precipitation (0.48), indicating that pollen assemblages in the artificial or human-disturbed vegetation reflect regional climate well. Comparison of pollen assemblages in different areas of northern China showed that pollen concentrations reflect the intensities of human impact to some degree. For example, pollen concentrations decrease as human impacts increase in intensity. The cereal pollen proportions in farmland differed by area. In Northeast China, cereal pollen proportions were distinctly higher than in most other areas of northern China, suggesting differences in planting habits and climate. 相似文献
827.
贺军华 《宁夏大学学报(自然科学版)》2010,31(4):399-401
运用问卷调查法和数理统计法,对宁夏大学校园体育文化节的发展与认知进行了分析,提出了校园体育文化节的各项评价指标,推动了宁夏大学校园体育文化节的发展,为以后更好地开展这项活动提供了理论依据. 相似文献
828.
In this paper, we consider testing the hypothesis that all multinomial populations in the stratified contingency table are identically distributed against the alternative that all these popula-tions are in simple tree order. We provide an asymptotic represen-tation of the order-restricted maximum likelihood estimate of the unknown parameters. The resulting estimators are proven to be n-consistent and asymptotically normal under appropriate con-ditions. A chi-squared test method is used for this hypothesis t... 相似文献
829.
<正>Autocorrelation is prevalent in continuous production processes,such as the processes in the chemical and pharmaceutical industries.With the development of measurement technology and data acquisition technology,sampling frequency is getting higher and the existence of autocorrelation cannot be ignored.This paper analyzes five estimation schemes of process capability for autocorrelated data.Comparisons among these schemes are discussed for small sample and large sample.In conclusion,this paper gives a procedure of process capability analysis for autocorrelated data. 相似文献
830.
<正> It is presented in this paper that the new design and its analysis of finite difference domaindecomposition algorithms for the two-dimensional heat equation,and the numerical results have shownthe stability and accuracy of the algorithms,where Saul'yev asymmetric schemes have been used atthe interface points.The Algorithm Ⅱ in this paper has further extended those developed by Dawsonand the others,Zhang and Shen. 相似文献