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   668篇
  免费   25篇
  国内免费   2篇
化学   467篇
晶体学   3篇
力学   13篇
数学   92篇
物理学   120篇
  2023年   7篇
  2022年   8篇
  2021年   13篇
  2020年   19篇
  2019年   13篇
  2018年   14篇
  2017年   16篇
  2016年   25篇
  2015年   25篇
  2014年   23篇
  2013年   45篇
  2012年   46篇
  2011年   55篇
  2010年   27篇
  2009年   30篇
  2008年   34篇
  2007年   26篇
  2006年   36篇
  2005年   47篇
  2004年   30篇
  2003年   18篇
  2002年   24篇
  2001年   14篇
  2000年   7篇
  1999年   6篇
  1998年   7篇
  1997年   5篇
  1996年   7篇
  1995年   5篇
  1993年   4篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   4篇
  1988年   8篇
  1987年   3篇
  1984年   4篇
  1982年   3篇
  1981年   2篇
  1980年   2篇
  1979年   2篇
  1977年   3篇
  1976年   5篇
  1975年   4篇
  1974年   2篇
  1972年   1篇
  1966年   2篇
  1963年   2篇
  1958年   2篇
  1874年   1篇
排序方式: 共有695条查询结果,搜索用时 15 毫秒
631.
An automorphism α of a group G is called a noetherian automorphism if for each ascending chain
of subgroups of G there is a positive integer m such that for all n ≥ m. The structure of the group of all noetherian automorphisms of a group is investigated in this paper.  相似文献   
632.
We model the evolution of the Internet at the autonomous system level as a process of competition for users and adaptation of bandwidth capability. From a weighted network formalism, where both nodes and links are weighted, we find the exponent of the degree distribution as a simple function of the growth rates of the number of autonomous systems and connections in the Internet, both empirically measurable quantities. Our approach also accounts for a high level of clustering as well as degree-degree correlations, both with the same hierarchical structure present in the real Internet. Further, it also highlights the interplay between bandwidth, connectivity, and traffic of the network.  相似文献   
633.
LetV be a Banach space whose dualV * is Va?ák, that is, weakly countably determined. Then an equivalent locally uniformly rotund norm onV is constructed. According to a recent example of Mercourakis, this is a real extension of an earlier result of Godefroy Troyanski, Whitfield and Zizler, whereV * has been a subspace of a weakly compactly generated Banach space.  相似文献   
634.
Two new cholera toxin (CT) ligands (4 and 5) are described. The new ligands were designed starting from the known GM1 mimics 2 and 3 by replacement of their GalNAc residue with the C4 isomer GlcNAc. As predicted by molecular modelling, the conformational properties of the equivalent pairs 2-4 and 3-5 are very similar and their affinity for CT is of the same order of magnitude. NMR experiments have also proved that 5 occupies the GM1-binding site of the toxin and have revealed its bound conformation.  相似文献   
635.
We consider the compressible steady state air flow in a porous medium caused by an extraction well and governed by Darcy's law. For a homogeneous soil matrix we have derived formulas (in 2-D and 3-D) to determine the effective radius of a single well depending on the well position and the depth of the domain. For inhomogeneous case (in 2-D) the influence of the heterogeneity, well position and the depth of the water table on the effective radius and on the pressure at the well is studied.  相似文献   
636.
We consider stationary air flow in a porous medium caused by extraction wells and governed by Darcy's law. Point sinks are described by Dirac functions. We distinguish two different situations: locally continuous and discontinuous conductivity near the wells. In both cases, well-posedness is proved. We propose a finite-element scheme in the general case and show the convergence of the approximated solution to the exact one.  相似文献   
637.
We analyze the influence of the nuclear wave functions generated from a set of different realistic soft-core two-body potentials on the coherent charged pion photoproduction on 3He nuclei at threshold and for small momentum transfers. This process is calculated in the framework of the impulse approximation including the Fermi motion. At threshold and below the resonance, our results reproduce fairly well the experimental data. At the first γN resonance region, the agreement with experiments varies with the momentum transfer.  相似文献   
638.
639.
640.
We use joint probabilities to analyze the EPR argument in the Bohm's example of spins.(1) The properties of distribution functions for two, three, or more noncommuting spin components are explicitly studied and their limitations are pointed out. Within the statistical ensemble interpretation of quantum theory (where only statements about repeated events can be made), the incompleteness of quantum theory does not follow, as the consistent use of joint probabilities shows. This does not exclude a completion of quantum mechanics, going beyond it, by a more general theory of single events, using hidden variables, for example.  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