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   1511211篇
  免费   32096篇
  国内免费   8214篇
化学   654202篇
晶体学   20214篇
力学   74428篇
综合类   102篇
数学   240019篇
物理学   366798篇
无线电   195758篇
  2021年   14729篇
  2020年   17360篇
  2019年   17490篇
  2018年   13259篇
  2016年   29630篇
  2015年   21741篇
  2014年   32757篇
  2013年   78605篇
  2012年   39233篇
  2011年   35470篇
  2010年   39317篇
  2009年   44383篇
  2008年   39048篇
  2007年   35900篇
  2006年   43051篇
  2005年   35153篇
  2004年   36709篇
  2003年   34661篇
  2002年   35701篇
  2001年   34494篇
  2000年   30946篇
  1999年   28697篇
  1998年   27355篇
  1997年   27251篇
  1996年   26849篇
  1995年   24681篇
  1994年   24134篇
  1993年   23513篇
  1992年   23091篇
  1991年   23361篇
  1990年   22107篇
  1989年   21723篇
  1988年   20850篇
  1987年   19641篇
  1986年   18437篇
  1985年   25005篇
  1984年   26197篇
  1983年   22167篇
  1982年   23629篇
  1981年   22818篇
  1980年   22064篇
  1979年   21907篇
  1978年   23195篇
  1977年   22742篇
  1976年   22339篇
  1975年   21002篇
  1974年   20607篇
  1973年   21137篇
  1972年   15342篇
  1967年   13118篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
281.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant.  相似文献   
282.
Fefelov  S. A.  Kazakova  L. P.  Bogoslovskiy  N. A.  Bylev  A. B.  Yakubov  A. O. 《Semiconductors》2020,54(4):450-453
Semiconductors - The current–voltage characteristics measured on Ge2Sb2Te5 thin films in the current mode are studied. The effect of multilevel recording is established when applying...  相似文献   
283.
Journal of Communications Technology and Electronics - Abstract—The article considers the two-dimensional diffraction problem of a TM-type plane electromagnetic wave on a cylindrical silver...  相似文献   
284.
285.
286.
Wireless Personal Communications - In the fusion experiment, sensitive radio frequency signal diagnostic instruments need to be protected against high power stray radiation coming from the Electron...  相似文献   
287.
In this paper, we present an approach of dynamic mesh adaptation for simulating complex 3‐dimensional incompressible moving‐boundary flows by immersed boundary methods. Tetrahedral meshes are adapted by a hierarchical refining/coarsening algorithm. Regular refinement is accomplished by dividing 1 tetrahedron into 8 subcells, and irregular refinement is only for eliminating the hanging points. Merging the 8 subcells obtained by regular refinement, the mesh is coarsened. With hierarchical refining/coarsening, mesh adaptivity can be achieved by adjusting the mesh only 1 time for each adaptation period. The level difference between 2 neighboring cells never exceeds 1, and the geometrical quality of mesh does not degrade as the level of adaptive mesh increases. A predictor‐corrector scheme is introduced to eliminate the phase lag between adapted mesh and unsteady solution. The error caused by each solution transferring from the old mesh to the new adapted one is small because most of the nodes on the 2 meshes are coincident. An immersed boundary method named local domain‐free discretization is employed to solve the flow equations. Several numerical experiments have been conducted for 3‐dimensional incompressible moving‐boundary flows. By using the present approach, the number of mesh nodes is reduced greatly while the accuracy of solution can be preserved.  相似文献   
288.
289.
290.
Puzanov  A. S.  Obolenskiy  S. V.  Kozlov  V. A. 《Semiconductors》2020,54(8):946-950
Semiconductors - On the basis of the Monte Carlo algorithm, a method for calculating the energy spectrum of hot nonequilibrium electrons and holes in the track of a primary recoil atom after being...  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