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   2289篇
  免费   112篇
  国内免费   95篇
化学   645篇
晶体学   13篇
力学   32篇
综合类   13篇
数学   377篇
物理学   143篇
综合类   1273篇
  2024年   3篇
  2023年   7篇
  2022年   18篇
  2021年   18篇
  2020年   30篇
  2019年   18篇
  2018年   30篇
  2017年   42篇
  2016年   40篇
  2015年   57篇
  2014年   72篇
  2013年   94篇
  2012年   97篇
  2011年   85篇
  2010年   75篇
  2009年   92篇
  2008年   116篇
  2007年   144篇
  2006年   158篇
  2005年   140篇
  2004年   181篇
  2003年   166篇
  2002年   113篇
  2001年   113篇
  2000年   84篇
  1999年   64篇
  1998年   56篇
  1997年   43篇
  1996年   54篇
  1995年   39篇
  1994年   43篇
  1993年   31篇
  1992年   19篇
  1991年   19篇
  1990年   9篇
  1989年   11篇
  1988年   12篇
  1987年   16篇
  1986年   7篇
  1985年   5篇
  1984年   10篇
  1983年   4篇
  1982年   5篇
  1981年   8篇
  1980年   12篇
  1979年   8篇
  1978年   10篇
  1977年   4篇
  1976年   9篇
  1974年   3篇
排序方式: 共有2496条查询结果,搜索用时 156 毫秒
211.
Starting from an effective Skyrme interaction we present a method to take into account the coupling between one- and two-phonon terms in the wave functions of excited states. The approach is a development of a finite rank separable approximation for the quasiparticle RPA calculations proposed in our previous work. The influence of the phonon-phonon coupling on energies and transition probabilities for the low-lying quadrupole and octupole states in the neutron-rich Sn isotopes is studied.  相似文献   
212.
Summary. N-Alkylation of certain angularly substituted heterocycles by C2- and C3-units provided appropriate precursors to construct stereoselectively the erythrinanone and several erythrinanone type analogues by intramolecular Friedel-Crafts acylation. The resulting aromatic ketones were catalytically reduced affording the corresponding parent frameworks including the hitherto unknown tetracyclus A-norschelhammerane. On the other hand, the stereoselective reduction of the carbonyl moiety offered a convenient approach to 11-hydroxylated erythrinanes with the natural occurring -configuration. The structures and the stereochemistry of the target compounds were proved by NMR spectroscopy.Part of PhD thesis, LMU München, D  相似文献   
213.
On the Existence of Solutions of Quasivariational Inclusion Problems   总被引:3,自引:0,他引:3  
Quasivariational inclusion problems are formulated and sufficient conditions on the existence of solutions are shown. As special cases, we obtain several results on the existence of solutions of general vector ideal, proper, Pareto, weak quasioptimization problems, quasivariational inequalities, and vector quasiequilibrium problems. Further, we prove theorems on the existence for solutions of systems of these inclusions. As a corollary, we obtain an ideal minimax theorem concerning vector functions.  相似文献   
214.
Many electrorheological fluids are suspensions consisting of solid particles and a carrier oil. If such a suspension is exposed to a strong electric field the effective viscosity increases dramatically. In this paper we first derive a model which captures this behaviour. For the resulting system of equations we then prove local in time existence of strong solutions for large data. For these solutions we finally derive error estimates for a fully implicit time-discretization.  相似文献   
215.
The N-heap Wythoffs game is a two-player impartial game with N piles of tokens of sizes Players take turns removing any number of tokens from a single pile, or removing (a1,..., aN) from all piles - ai tokens from the i-th pile, providing that where is the nim addition. The first player that cannot make a move loses. Denote all the P-positions (i.e., losing positions) by Two conjectures were proposed on the game by Fraenkel [7]. When are fixed, i) there exists an integer N1 such that when . ii) there exist integers N2 and _2 such that when , the golden section.In this paper, we provide a sufficient condition for the conjectures to hold, and subsequently prove them for the three-heap Wythoffs game with the first piles having up to 10 tokens.AMS Subject Classification: 91A46, 68R05.  相似文献   
216.
217.
-particles from fusion reactions in a DT magnetized plasma are confined inside the plasma not only by magnetic fields but also by induced electric fields which are due to the different mobilities of -particles and electrons. Criteria are derived for the -confinement in a cylindrical plasma, inertially confined by a heavy liner. It is observed that the suprathermal population in the DT plasma will influence the overall dynamics.  相似文献   
218.
The paper considers instability of a symmetric linear ion chain against a spontaneous distortion that orders ions of opposite charge without a multiple change in the spacing. Transverse deformation in dense chains is observed. The dipolar interaction responsible for 3D ordering of similar structures of Cu—O chains in yttrium perovskites has been assessed. The superclose ion packing in Cu—O chains is explained by the existence of an oriented hole orbital in the electronic structure of bivalent copper. The possible role of this orbital as an additional degree of freedom leading to thermodynamic singularities at intermediate temperatures below the tetra–ortho transition temperature has been investigated.  相似文献   
219.
A plane Darcy filtration convection problem for rectangular containers elongated in the vertical direction is considered. By the spectraldifference method, which preserved cosymmetry of the initial problem, evolution of families of stationary regimes from the onset of instability on the primary family till the collision of the families is studied.  相似文献   
220.
Goginava  U. 《Mathematical Notes》2003,74(3-4):477-482
Zhizhiashvili studied questions associated with the approximation properties of Cesàro means of trigonometric Fourier series for functions of two variables in the spaces H. It is proved here that the corresponding estimate cannot be improved for p = 1 or p = .  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