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   787863篇
  免费   8723篇
  国内免费   2230篇
化学   408179篇
晶体学   9397篇
力学   38356篇
综合类   26篇
数学   105322篇
物理学   237536篇
  2021年   6991篇
  2020年   7681篇
  2019年   8588篇
  2018年   11209篇
  2017年   11171篇
  2016年   16336篇
  2015年   9597篇
  2014年   15312篇
  2013年   35846篇
  2012年   27645篇
  2011年   33368篇
  2010年   24315篇
  2009年   24076篇
  2008年   31279篇
  2007年   31003篇
  2006年   28651篇
  2005年   25621篇
  2004年   23749篇
  2003年   21158篇
  2002年   20939篇
  2001年   22664篇
  2000年   17509篇
  1999年   13677篇
  1998年   11574篇
  1997年   11282篇
  1996年   10802篇
  1995年   9518篇
  1994年   9488篇
  1993年   9123篇
  1992年   9893篇
  1991年   10271篇
  1990年   9947篇
  1989年   9584篇
  1988年   9473篇
  1987年   9345篇
  1986年   8835篇
  1985年   11521篇
  1984年   11932篇
  1983年   9789篇
  1982年   10167篇
  1981年   9754篇
  1980年   9136篇
  1979年   9888篇
  1978年   10190篇
  1977年   10107篇
  1976年   9991篇
  1975年   9471篇
  1974年   9324篇
  1973年   9529篇
  1972年   6859篇
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
61.
Crystallography Reports - Crystals of mutants of uridine phosphorylase from Shewanella oneidensis MR-1 at the active-site threonine residue were obtained, and the three-dimensional structures of...  相似文献   
62.
Crystallography Reports - The review describes the application of small-angle scattering (SAS) of neutrons and complementary methods to study the structures of biomacromolecules. Here we cover SAS...  相似文献   
63.
We investigate the possibility of phantom crossing in the dark energy sector and the solution for the Hubble tension between early and late universe observations. We use robust combinations of different cosmological observations, namely the Cosmic Microwave Background (CMB), local measurement of Hubble constant (H0), Baryon Acoustic Oscillation (BAO) and SnIa for this purpose. For a combination of CMB+BAO data that is related to early universe physics, phantom crossing in the dark energy sector was confirmed at a 95% confidence level and we obtained the constraint H0=71.03.8+2.9 km/s/Mpc at a 68% confidence level, which is in perfect agreement with the local measurement by Riess et al. We show that constraints from different combinations of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. For the combination of all data considered, we obtained the constraint H0=70.25±0.78 km/s/Mpc at a 68% confidence level and the phantom crossing happening at the scale factor am=0.8510.031+0.048 at a 68% confidence level.  相似文献   
64.
Algebra and Logic - Unary functions definable in o-stable ordered groups of nonvaluational type are studied. Such functions are proved to be piecewise monotone and continuous.  相似文献   
65.
66.
Journal of Applied Mechanics and Technical Physics - A refined model of viscoelastic-plastic deformation of flexible plates with spatial reinforcement structures has been developed. Strains of the...  相似文献   
67.
Russian Physics Journal - A unified equation for the pressure drop in the apparatus with the stationary and fluidized granular layers is derived. The resulting recurrent equation is used to...  相似文献   
68.
Pentafluorosulfanyl (SF5)-containing compounds and corresponding analogs are a highly valuable class of fluorine-containing building blocks owing to their unique properties. The reason for that is the set of peculiar and tremendously beneficial characteristics they can impart on molecules once introduced onto them. Despite this, their application in distinct scientific fields remains modest, given the extremely harsh reaction conditions needed to access such compounds. The recent synthetic approaches via S−F, and C−SF5 bond formation as well as the use of SF5-containing building blocks embody a “stairway-to-heaven” loophole in the synthesis of otherwise-inaccessible chemical scaffolds only a few years ago. Herein, we report and evaluate the properties of the SF5 group and analogs, by summarizing synthetic methodologies available to access them as well as following applications in material science and medicinal chemistry since 2015.  相似文献   
69.
Filippov  A. N. 《Colloid Journal》2022,84(3):332-343
Colloid Journal - The capillary-osmosis and reverse-osmosis coefficients of an ion-exchange membrane have been calculated as the kinetic coefficients of the Onsager matrix within the thermodynamics...  相似文献   
70.
Doklady Mathematics - The integrability of certain classes of homogeneous dynamical systems on the tangent bundles of four-dimensional manifolds is shown. The force fields involved in the systems...  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