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   788489篇
  免费   8731篇
  国内免费   2231篇
化学   408426篇
晶体学   9267篇
力学   38328篇
综合类   26篇
数学   105628篇
物理学   237776篇
  2021年   6995篇
  2020年   7684篇
  2019年   8592篇
  2018年   11198篇
  2017年   11169篇
  2016年   16340篇
  2015年   9592篇
  2014年   15323篇
  2013年   35870篇
  2012年   27649篇
  2011年   33394篇
  2010年   24341篇
  2009年   24098篇
  2008年   31310篇
  2007年   31042篇
  2006年   28673篇
  2005年   25680篇
  2004年   23788篇
  2003年   21186篇
  2002年   20962篇
  2001年   22688篇
  2000年   17542篇
  1999年   13705篇
  1998年   11593篇
  1997年   11105篇
  1996年   10007篇
  1995年   9524篇
  1994年   9509篇
  1993年   9144篇
  1992年   9909篇
  1991年   10298篇
  1990年   9959篇
  1989年   9610篇
  1988年   9489篇
  1987年   9366篇
  1986年   8864篇
  1985年   11553篇
  1984年   11965篇
  1983年   9814篇
  1982年   10206篇
  1981年   9796篇
  1980年   9172篇
  1979年   9913篇
  1978年   10225篇
  1977年   10137篇
  1976年   10022篇
  1975年   9487篇
  1974年   9346篇
  1973年   9550篇
  1972年   6883篇
排序方式: 共有10000条查询结果,搜索用时 62 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