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   467542篇
  免费   3743篇
  国内免费   1190篇
化学   238370篇
晶体学   7320篇
力学   21591篇
综合类   8篇
数学   62289篇
物理学   142897篇
  2019年   3254篇
  2018年   11590篇
  2017年   12257篇
  2016年   9740篇
  2015年   4570篇
  2014年   6049篇
  2013年   16359篇
  2012年   15134篇
  2011年   24768篇
  2010年   16082篇
  2009年   16025篇
  2008年   22293篇
  2007年   25403篇
  2006年   12856篇
  2005年   17229篇
  2004年   13335篇
  2003年   12409篇
  2002年   10376篇
  2001年   10989篇
  2000年   8708篇
  1999年   6533篇
  1998年   5415篇
  1997年   5477篇
  1996年   5350篇
  1995年   4601篇
  1994年   4586篇
  1993年   4487篇
  1992年   5071篇
  1991年   5037篇
  1990年   4876篇
  1989年   4943篇
  1988年   4799篇
  1987年   4770篇
  1986年   4506篇
  1985年   5988篇
  1984年   6128篇
  1983年   5034篇
  1982年   5441篇
  1981年   5268篇
  1980年   4986篇
  1979年   5380篇
  1978年   5699篇
  1977年   5522篇
  1976年   5421篇
  1975年   5108篇
  1974年   5075篇
  1973年   5218篇
  1972年   3485篇
  1968年   3438篇
  1967年   3821篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
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   
42.
43.
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   
44.
45.
Journal of Sol-Gel Science and Technology - In this paper, a simple method is presented for making a conductive and hydrophobic cotton fabric using a multi-walled carbon nanotube (MWCNT). The...  相似文献   
46.
47.
We summarize the results of our recent work on Bäcklund transformations (BTs), particularly focusing on the relation between BTs and infinitesimal symmetries. We present a BT for an associated Degasperis–Procesi (aDP) equation and its superposition principle and investigate the solutions generated by applying this BT. Following our general methodology, we use the superposition principle of the BT to generate the infinitesimal symmetries of the aDP equation.  相似文献   
48.
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   
49.
50.
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   
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