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   19879篇
  免费   2033篇
  国内免费   841篇
化学   14600篇
晶体学   144篇
力学   651篇
综合类   47篇
数学   2495篇
物理学   4816篇
  2023年   257篇
  2022年   305篇
  2021年   374篇
  2020年   497篇
  2019年   507篇
  2018年   389篇
  2017年   369篇
  2016年   765篇
  2015年   803篇
  2014年   907篇
  2013年   1475篇
  2012年   1710篇
  2011年   1629篇
  2010年   1047篇
  2009年   886篇
  2008年   1365篇
  2007年   1237篇
  2006年   1242篇
  2005年   1082篇
  2004年   905篇
  2003年   738篇
  2002年   659篇
  2001年   370篇
  2000年   309篇
  1999年   245篇
  1998年   208篇
  1997年   223篇
  1996年   249篇
  1995年   175篇
  1994年   168篇
  1993年   166篇
  1992年   117篇
  1991年   99篇
  1990年   102篇
  1989年   76篇
  1988年   65篇
  1987年   55篇
  1986年   85篇
  1985年   103篇
  1984年   77篇
  1983年   48篇
  1982年   61篇
  1981年   63篇
  1980年   64篇
  1979年   49篇
  1978年   53篇
  1977年   39篇
  1976年   51篇
  1975年   29篇
  1973年   28篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
We prove that the quasi continuous version of a functional in Epr is continuous along the sample paths of the Dirichlet process provided that p>2, 0<r?1 and pr>2, without assuming the Meyer equivalence. Parallel results for multi-parameter processes are also obtained. Moreover, for 1<p<2, we prove that a n parameter Dirichlet process does not touch a set of (p,2n)-zero capacity. As an example, we also study the quasi-everywhere existence of the local times of martingales on path space.  相似文献   
92.
Navier-Stokes方程带Backtracking技巧的两重网格算法   总被引:3,自引:1,他引:2  
1 引 言考虑二维不可压 Navier-Stokes方程:  相似文献   
93.
In this article, the linear and nonlinear shear rheological behaviors of polylactide (PLA)/clay (organophilic‐montmorillonite) nanocomposites (PLACNs) were investigated by an Advanced Rheology Expanded System rheometer. The nanocomposites were prepared by master batch method using a twin‐screw extruder with poly(ε‐caprolactone) (PCL) as a compatibilizer. The presence of org‐MMT leads to obvious pseudo‐solid‐like behaviors of nanocomposite melts. The behaviors caused by the formation of a “percolating network” derived from the reciprocity among the strong related sheet particles. Therefore, the storage moduli, loss moduli, and dynamic viscosities of PLACNs show a monotonic increase with MMT content. Nonterminal behaviors exists in PLACNs nanocomposites. Besides the PLACNs melts show a greater shear thinning tendency than pure PLA melt because of the preferential orientation of the MMT layers. Therefore, PLACNs have higher moduli but better processibility compared with pure PLA. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3189–3196, 2007  相似文献   
94.
The central zinc(II) atom in the title complex is tetrahedrally coordinated by four nitrogen atoms derived from 4‐methyl‐5‐imidazolecarboxyaldehyde ligands with Zn? N in the range 2.007(3) to 2.026(4) Å. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
95.
Theoretical models for Monte Carlo simulation of radiative processes, i.e. bremsstrahlung and characteristic x-ray emission, are presented. Possible strategies for simulating electron transport are briefly described. For mechanisms involving energy loss and angular deflections, difficulties for strict implementation of accurate numerical differential cross sections still remain due to the strong correlations between these variables. Practical solutions for the case of inelastic collisions and bremsstrahlung emission are described. Comparisons of simulation results with experimental data for several problems of interest in electron probe microanalysis are presented.  相似文献   
96.
JPC – Journal of Planar Chromatography – Modern TLC - Two interfaces have been tested for coupling thin-layer chromatography (TLC) with time-of-flight secondary-ion mass spectrometry...  相似文献   
97.
The terminology ‘ID frequency’(w ID) is proposed after analyzing the 1D active photonic crystal based on the transfer matrix method. The relationship between wID and the structure parameters of the photonic crystal is investigated.  相似文献   
98.
Elastic electron scattering on the exotic light nucleus28S is investigated in the plane wave Born approximation. The variation of the squared form factors of28S with momentum transfer is compared with that of32S. It is found that the behavior of the form factors near the second minimum (with a moderate momentum transfer) is sensitive to the alteration of the charge density distribution of halo protons in28S. This indicates that elastic electron scattering can be a good probe of the structure of proton-halo nuclei.  相似文献   
99.
The source waves are some particular solutions to genuinely non linear hyperbolic systems with a source term, whose propagation velocity is a constant determined by the roots of this source term. We propose a system of 2 equations on a 2 dimension space, which model the velocity field of the atmosphere near the ground. The source term is made of three parts: a given pressure gradient, a friction or aspiration effect and the Coriolis force. In the case where these parameters are constant, we build a solution which is a constant outside a circular crown. The internal circle represents the eye's wall of the hurricane and corresponds to a share shock wave. The external circle is a set generating the bifurcation which actually models the hurricane. To cite this article: A.-Y. LeRoux et al., C. R. Acad. Sci. Paris, Ser. I 339 (2004).  相似文献   
100.
We prove a duality theorem for some logarithmic D-modules associated with a class of divisors. We also give some results for the locally quasi-homogeneous case. To cite this article: F.J. Castro-Jiménez, J.M. Ucha-Enr??quez, C. R. Acad. Sci. Paris, Ser. I 338 (2004).  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