首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   117篇
  免费   0篇
  国内免费   2篇
化学   25篇
力学   1篇
数学   63篇
物理学   30篇
  2024年   1篇
  2022年   1篇
  2021年   3篇
  2020年   2篇
  2019年   4篇
  2018年   1篇
  2017年   1篇
  2015年   4篇
  2014年   3篇
  2013年   2篇
  2012年   8篇
  2011年   4篇
  2010年   6篇
  2009年   3篇
  2008年   2篇
  2007年   3篇
  2006年   5篇
  2005年   2篇
  2004年   4篇
  2003年   4篇
  2002年   5篇
  2001年   3篇
  2000年   5篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1996年   4篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1989年   2篇
  1985年   2篇
  1984年   1篇
  1982年   1篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1973年   2篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1969年   3篇
  1967年   3篇
  1966年   2篇
排序方式: 共有119条查询结果,搜索用时 45 毫秒
51.
For a sequenceA = {Ak} k?1 of positive constants letP A = {p(x): p(x) = Σ k?1 n a k x k ,n = 1,2, …, ¦a k ≦ A k k }. We consider the rate of approximation by elements ofP A , of continuous functions in [0, 1] which vanish at x = 0. Also a classP A is called “efficient” if globally it guarantees the Jackson rate of approximation. Some necessary conditions for efficiency and some sufficient ones are derived.  相似文献   
52.
53.
54.
55.
56.
57.
Let I be a finite interval, r and ρ(t)=dist{t, ∂I}, tI. Denote by Δs+Wrpα, 0α<∞, the class of functions x on I with the seminorm x(r)ραLp1 for which Δsτx, τ>0, is nonnegative on I. We obtain two-sided estimates of the Kolmogorov widths dn(Δs+Wrpα)Lq and of the linear widths dn(Δs+Wrpα)linLq, s=0, 1, …, r+1.  相似文献   
58.
NAIMA as a solution for future GMO diagnostics challenges   总被引:1,自引:0,他引:1  
In the field of genetically modified organism (GMO) diagnostics, real-time PCR has been the method of choice for target detection and quantification in most laboratories. Despite its numerous advantages, however, the lack of a true multiplexing option may render real-time PCR less practical in the face of future GMO detection challenges such as the multiplicity and increasing complexity of new transgenic events, as well as the repeated occurrence of unauthorized GMOs on the market. In this context, we recently reported the development of a novel multiplex quantitative DNA-based target amplification method, named NASBA implemented microarray analysis (NAIMA), which is suitable for sensitive, specific and quantitative detection of GMOs on a microarray. In this article, the performance of NAIMA is compared with that of real-time PCR, the focus being their performances in view of the upcoming challenge to detect/quantify an increasing number of possible GMOs at a sustainable cost and affordable staff effort. Finally, we present our conclusions concerning the applicability of NAIMA for future use in GMO diagnostics.  相似文献   
59.
Logic and Colour     
In this paper evidence will be provided that Wittgenstein??s intuition about the logic of colour relations is to be taken near-literally. Starting from the Aristotelian oppositions between propositions as represented in the logical square of oppositions on the one hand and oppositions between primary and secondary colors as represented in an octahedron on the other, it will be shown algebraically how definitions for the former carry over to the realm of colour categories and describe very precisely the relations obtaining between the known primary and secondary colours. Linguistic evidence for the reality of the resulting isomorphism will be provided. For example, the vertices that resist natural single-item lexicalization in logic (such as the O-corner, for which there is no natural lexicalization *nall (=not all)) are not naturally lexicalized in the realm of colour terms either. From the perspective of the architecture of cognition, the isomorphism suggests that the foundations of logical oppositions and negation may well be much more deeply rooted in the physiological structure of human cognition than is standardly assumed.  相似文献   
60.
We study the evolution of the dynamics across a generic first-order quantum phase transition in an interacting boson model of nuclei. The dynamics inside the phase coexistence region exhibits a very simple pattern. A classical analysis reveals a robustly regular dynamics confined to the deformed region and well separated from a chaotic dynamics ascribed to the spherical region. A quantum analysis discloses regular bands of states in the deformed region, which persist to energies well above the phase-separating barrier, in the face of a complicated environment. The impact of kinetic collective rotational terms on this intricate interplay of order and chaos is investigated.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号