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   237925篇
  免费   2930篇
  国内免费   854篇
化学   128951篇
晶体学   3957篇
力学   10352篇
综合类   15篇
数学   22509篇
物理学   75925篇
  2018年   1716篇
  2016年   2991篇
  2015年   2199篇
  2014年   3200篇
  2013年   9824篇
  2012年   6982篇
  2011年   8811篇
  2010年   5949篇
  2009年   5922篇
  2008年   7964篇
  2007年   8012篇
  2006年   7591篇
  2005年   6952篇
  2004年   6331篇
  2003年   5687篇
  2002年   5531篇
  2001年   7794篇
  2000年   5823篇
  1999年   4573篇
  1998年   3536篇
  1997年   3547篇
  1996年   3349篇
  1995年   3108篇
  1994年   2935篇
  1993年   2790篇
  1992年   3444篇
  1991年   3362篇
  1990年   3206篇
  1989年   3158篇
  1988年   3087篇
  1987年   3134篇
  1986年   2880篇
  1985年   3930篇
  1984年   3912篇
  1983年   3147篇
  1982年   3335篇
  1981年   3274篇
  1980年   3147篇
  1979年   3385篇
  1978年   3669篇
  1977年   3458篇
  1976年   3375篇
  1975年   3149篇
  1974年   3117篇
  1973年   3085篇
  1972年   1958篇
  1971年   1596篇
  1968年   2048篇
  1967年   2248篇
  1966年   1992篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
The European Physical Journal Special Topics - The removal of suspended particles from the interior of a thermocapillary liquid bridge via a finite-particle-size effect restricting the particle...  相似文献   
23.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.  相似文献   
24.
25.
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   
26.
27.
28.
Su  X. F.  Zhang  Y. L.  Maximov  A. L.  Zhang  K.  Xin  Q.  Feng  C. Q.  Bai  X. F.  Wu  W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,...  相似文献   
29.
In this communication, we report the synthesis of small‐sized (<10 nm), water‐soluble, magnetic nanoparticles (MNPs) coated with polyhedral oligomeric silsesquioxanes (POSS), which contain either polyethylene glycol (PEG) or octa(tetramethylammonium) (OctaTMA) as functional groups. The POSS‐coated MNPs exhibit superparamagnetic behavior with saturation magnetic moments (51–53 emu g?1) comparable to silica‐coated MNPs. They also provide good colloidal stability at different pH and salt concentrations, and low cytotoxicity to MCF‐7 human breast epithelial cells. The relaxivity data and magnetic resonance (MR) phantom images demonstrate the potential application of these MNPs in bioimaging.  相似文献   
30.
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