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   1351996篇
  免费   29886篇
  国内免费   7766篇
化学   674231篇
晶体学   14194篇
力学   75218篇
综合类   115篇
数学   244659篇
物理学   381231篇
  2021年   12700篇
  2020年   15970篇
  2019年   16101篇
  2018年   14028篇
  2016年   28568篇
  2015年   20968篇
  2014年   30544篇
  2013年   74535篇
  2012年   41281篇
  2011年   40078篇
  2010年   39439篇
  2009年   41231篇
  2008年   37991篇
  2007年   34124篇
  2006年   38727篇
  2005年   31752篇
  2004年   32125篇
  2003年   29201篇
  2002年   26751篇
  2001年   28873篇
  2000年   23737篇
  1999年   20719篇
  1998年   18922篇
  1997年   19457篇
  1996年   19299篇
  1995年   18644篇
  1994年   18184篇
  1993年   17719篇
  1992年   18036篇
  1991年   18227篇
  1990年   17464篇
  1989年   17458篇
  1988年   17109篇
  1987年   17045篇
  1986年   15955篇
  1985年   22412篇
  1984年   23594篇
  1983年   19631篇
  1982年   21303篇
  1981年   20533篇
  1980年   19833篇
  1979年   20266篇
  1978年   21485篇
  1977年   21154篇
  1976年   20896篇
  1975年   19608篇
  1974年   19254篇
  1973年   19729篇
  1972年   14257篇
  1967年   12657篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Ferrarini  A.  Finotello  A.  Salsano  G.  Auricchio  F.  Palombo  D.  Spinella  G.  Pane  B.  Conti  M. 《Acta Mechanica Sinica》2021,37(7):1192-1192
Acta Mechanica Sinica - A Correction to this paper has been published: https://doi.org/10.1007/s10409-021-01066-2  相似文献   
82.
Siberian Mathematical Journal - We obtain some new estimates that show the extremality of the Rademacher system in the set of sequences of independent functions considered in rearrangement...  相似文献   
83.
Theoretical and Mathematical Physics - We present a one-line closed-form expression for the three-parameter breather of the nonlinear Schrödinger equation. This provides an analytic proof of...  相似文献   
84.
Journal of Fourier Analysis and Applications - We develop a theory of Sobolev orthogonal polynomials on the Sierpiński gasket ( $$SG$$ ), which is a fractal set that can be viewed as a limit...  相似文献   
85.
Journal of Applied Spectroscopy - It is shown that the relations for determining a purely electronic transition from diffuse absorption or emission spectra, obtained under the assumption of...  相似文献   
86.
In this article, the effect of ionization on the energy spectrum of electrons within the interaction of a laser pulse with hydrogen atoms is investigated using particle-in-cell simulation codes. The results show that the behaviour of electrons' energy distribution function in the field-ionized plasma, which occurred due to the field ionization, compared with that in the pre-plasma strongly depends on the pulse shape. For short rise-time pulses (here 30 fs), due to the rapid enhancement of laser electric field, ionization occurs quickly, and as a result, there is not much difference in the electron energy in both the media. However, for pulses with rise time of 40 fs, in the pre-plasma state, the electron population reaches higher energies compared with the field-ionized plasma state. The main reason for this difference is the nonlinear wave breaking that happens earlier due to density inhomogeneity in the field-ionized plasma. On the other hand, at longer rise-time pulses (here 60 and 70 fs), electrons achieve higher energies in the field-ionized plasma than those in the case of pre-plasma. In this case, because of density fluctuations in the field-ionized plasma, the Raman backscattered radiations are seeded by a strong initial noise at the earlier times and the Mendonca condition for chaos threshold is met sooner. Therefore, the electrons gain more energy through the stochastic mechanism that is in agreement with chaotic nature of the motion.  相似文献   
87.
Radiophysics and Quantum Electronics - This work is a review of recent results, which have been obtained within the framework of the mathematical theory of dynamical chaos and are related to the...  相似文献   
88.
Garmanova  T. A. 《Mathematical Notes》2021,109(3-4):527-533
Mathematical Notes - The paper deals with sharp estimates of derivatives of intermediate order $$k\le n-1$$ in the Sobolev space $$\mathring W^n_2[0;1]$$ , $$n\in\mathbb N$$ . The functions...  相似文献   
89.
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation.  相似文献   
90.
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