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   303072篇
  免费   2433篇
  国内免费   705篇
化学   145647篇
晶体学   3855篇
力学   15223篇
综合类   5篇
数学   44603篇
物理学   96877篇
  2018年   10621篇
  2017年   11519篇
  2016年   6718篇
  2015年   2814篇
  2014年   2859篇
  2013年   8516篇
  2012年   10218篇
  2011年   20071篇
  2010年   12401篇
  2009年   12384篇
  2008年   17435篇
  2007年   21055篇
  2006年   6569篇
  2005年   13026篇
  2004年   8965篇
  2003年   8166篇
  2002年   5957篇
  2001年   6278篇
  2000年   4953篇
  1999年   3729篇
  1998年   2931篇
  1997年   2869篇
  1996年   2796篇
  1995年   2631篇
  1994年   2495篇
  1993年   2342篇
  1992年   2825篇
  1991年   2706篇
  1990年   2662篇
  1989年   2670篇
  1988年   2620篇
  1987年   2616篇
  1986年   2426篇
  1985年   3324篇
  1984年   3354篇
  1983年   2745篇
  1982年   2951篇
  1981年   2907篇
  1980年   2772篇
  1979年   2976篇
  1978年   3239篇
  1977年   2962篇
  1976年   2946篇
  1975年   2780篇
  1974年   2722篇
  1973年   2774篇
  1972年   1763篇
  1968年   2026篇
  1967年   2166篇
  1966年   1971篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
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   
25.
26.
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   
27.
28.
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   
29.
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   
30.
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   
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