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   225366篇
  免费   5928篇
  国内免费   4747篇
化学   102707篇
晶体学   3059篇
力学   14021篇
综合类   325篇
数学   39324篇
物理学   76605篇
  2022年   1442篇
  2021年   2207篇
  2020年   2571篇
  2019年   2761篇
  2018年   11669篇
  2017年   12244篇
  2016年   7929篇
  2015年   3483篇
  2014年   4197篇
  2013年   6477篇
  2012年   10528篇
  2011年   19028篇
  2010年   12335篇
  2009年   12469篇
  2008年   16176篇
  2007年   19348篇
  2006年   5293篇
  2005年   10775篇
  2004年   7217篇
  2003年   6968篇
  2002年   5135篇
  2001年   3968篇
  2000年   3222篇
  1999年   2390篇
  1998年   2148篇
  1997年   1876篇
  1996年   1882篇
  1995年   1610篇
  1994年   1646篇
  1993年   1527篇
  1992年   1544篇
  1991年   1617篇
  1990年   1604篇
  1989年   1493篇
  1988年   1410篇
  1987年   1397篇
  1986年   1295篇
  1985年   1411篇
  1984年   1441篇
  1983年   1219篇
  1982年   1237篇
  1981年   1134篇
  1980年   1056篇
  1979年   1282篇
  1978年   1281篇
  1977年   1200篇
  1976年   1359篇
  1975年   1187篇
  1974年   1181篇
  1973年   1233篇
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
41.
42.
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   
43.
Journal of Sol-Gel Science and Technology - A novel gas sensing material, La–Y co-doped TiO2 nanoparticles, was synthesized by sol–gel method and applied to detect organic pollutants...  相似文献   
44.
45.
46.
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   
47.
Nanocomposites based on poly-N-vinylcaprolactam (PVC), characterized by different drying temperatures of aqueous PVC solution at 25°С (PVC25) and 40°С (PVC40), with titanium(IV) oxide nanoparticles (TONs) (η-phase (TP: TiO2 – x · mH2O) with a superstructure to the anatase structure and ordered solid solution with partial replacement of oxygen atoms in the η-phase with peroxo group O 2 2– (PP: TiO x (O2)2 – x · nH2O)) have been obtained for the first time and characterized by X-ray diffraction and IR spectroscopy. It is found that a common feature of TP/PVC and PP/PVC obtained by dry mixing and grinding is the decrease in the number of water molecules for TP and PP in the interlayer space of the structure and their attachment to the PVC amide groups; the differences are related to the specificity of PVC behavior in these systems: mechanodestruction of PVC in PP/PVC40 and different numbers of water molecules in PVC25 and PVC40.  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.
Theoretical and Computational Fluid Dynamics - The present study aims to simulate a collision of two droplets containing immiscible liquids by employing a three- dimensional incompressible smoothed...  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