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   335880篇
  免费   4749篇
  国内免费   1960篇
化学   169971篇
晶体学   4526篇
力学   15953篇
综合类   117篇
数学   39602篇
物理学   112420篇
  2021年   3369篇
  2020年   3670篇
  2019年   4086篇
  2018年   5453篇
  2017年   5709篇
  2016年   7808篇
  2015年   4537篇
  2014年   7566篇
  2013年   16599篇
  2012年   13202篇
  2011年   15660篇
  2010年   11602篇
  2009年   11442篇
  2008年   13825篇
  2007年   13696篇
  2006年   12568篇
  2005年   10879篇
  2004年   10176篇
  2003年   8994篇
  2002年   9012篇
  2001年   10653篇
  2000年   7810篇
  1999年   6166篇
  1998年   5107篇
  1997年   4917篇
  1996年   4282篇
  1995年   3846篇
  1994年   3821篇
  1993年   3693篇
  1992年   4078篇
  1991年   4297篇
  1990年   4044篇
  1989年   3956篇
  1988年   3722篇
  1987年   3878篇
  1986年   3646篇
  1985年   4589篇
  1984年   4631篇
  1983年   3833篇
  1982年   3914篇
  1981年   3648篇
  1980年   3598篇
  1979年   3883篇
  1978年   3867篇
  1977年   3886篇
  1976年   3865篇
  1975年   3642篇
  1974年   3593篇
  1973年   3623篇
  1972年   2584篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Sukhorukova  O. S.  Tarasenko  A. S.  Tarasenko  S. V.  Shavrov  V. G. 《JETP Letters》2020,112(7):420-427
JETP Letters - At the resonant passage of a plane elastic shear wave through an acoustically continuous heterostructure consisting of magnetic and nonmagnetic layers in a symmetric nonmagnetic...  相似文献   
152.
Zahra  S.  Shafaq  B.  Kanwal  B. 《Physics of Atomic Nuclei》2020,83(5):770-772
Physics of Atomic Nuclei - Based on the behavior of elastic scattering of proton and anti-proton at $$\sqrt{s}=1.96$$ TeV for squared four-momentum transfer $$0.26<{-}t<1.2($$ GeV...  相似文献   
153.
154.

The diffusive behavior of nanoparticles inside porous materials is attracting a lot of interest in the context of understanding, modeling, and optimization of many technical processes. A very powerful technique for characterizing the diffusive behavior of particles in free media is dynamic light scattering (DLS). The applicability of the method in porous media is considered, however, to be rather difficult due to the presence of multiple sources of scattering. In contrast to most of the previous approaches, the DLS method was applied without ensuring matching refractive indices of solvent and porous matrix in the present study. To test the capabilities of the method, the diffusion of spherical gold nanoparticles within the interconnected, periodic nanopores of inverse opals was analyzed. Despite the complexity of this system, which involves many interfaces and different refractive indices, a clear signal related to the motion of particles inside the porous media was obtained. As expected, the diffusive process inside the porous sample slowed down compared to the particle diffusion in free media. The obtained effective diffusion coefficients were found to be wave vector-dependent. They increased linearly with increasing spatial extension of the probed particle concentration fluctuations. On average, the slowing-down factor measured in this work agrees within combined uncertainties with literature data.

  相似文献   
155.
156.
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method.  相似文献   
157.
158.
159.
Small molecule additives have been shown to increase the device efficiency of conjugated polymer (donor) and fullerene derivative (acceptor) based organic solar cells by modifying the morphology of the device active layer. In this paper we conduct a systematic study of how additives affect the donor‐acceptor morphology using molecular dynamics simulations of blends of thiophene‐based oligomers, mimicking poly(3‐dodecylthiophene) (P3DDT) or poly(2,2′:5′,2”‐3,3”‐didocyl‐terthiophene) (PTTT), and fullerene derivatives with additives of varying length and chemical functionalization, mimicking experimentally used additives like methyl ester additives, diiodooctane, and alkanedithiols. We find that functionalization of additives with end groups that are attracted to acceptor molecules are necessary to induce increased donor‐acceptor macrophase separation. In blends where acceptors intercalate between oligomer alkyl side chains, functionalized additives decrease acceptor intercalation. Functionalized additives with shorter alkyl segments increase acceptor macrophase separation more than additives with same chemical functionalization but longer alkyl segments. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1046–1057  相似文献   
160.
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