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   1439714篇
  免费   44969篇
  国内免费   17558篇
化学   732030篇
晶体学   21295篇
力学   81161篇
综合类   628篇
数学   253365篇
物理学   413762篇
  2021年   16741篇
  2020年   19079篇
  2019年   19583篇
  2018年   16783篇
  2017年   15299篇
  2016年   32507篇
  2015年   24862篇
  2014年   35491篇
  2013年   80889篇
  2012年   46944篇
  2011年   45328篇
  2010年   43252篇
  2009年   45351篇
  2008年   41045篇
  2007年   36706篇
  2006年   40996篇
  2005年   33012篇
  2004年   33095篇
  2003年   30525篇
  2002年   31270篇
  2001年   30938篇
  2000年   26595篇
  1999年   24473篇
  1998年   22746篇
  1997年   22609篇
  1996年   22775篇
  1995年   20516篇
  1994年   19955篇
  1993年   19164篇
  1992年   19169篇
  1991年   19361篇
  1990年   18430篇
  1989年   18266篇
  1988年   17698篇
  1987年   17652篇
  1986年   16610篇
  1985年   22938篇
  1984年   24061篇
  1983年   20167篇
  1982年   21788篇
  1981年   20993篇
  1980年   20314篇
  1979年   20522篇
  1978年   21759篇
  1977年   21359篇
  1976年   21073篇
  1975年   19727篇
  1974年   19379篇
  1973年   19824篇
  1972年   14310篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
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   
122.
Faul  Peter F. 《Semigroup Forum》2021,102(3):655-673
Semigroup Forum - It is well known that the set of isomorphism classes of extensions of groups with abelian kernel is characterized by the second cohomology group. In this paper we generalise this...  相似文献   
123.
Kumar  Sanjay  Jiwari  Ram  Mittal  R. C.  Awrejcewicz  Jan 《Nonlinear dynamics》2021,104(1):661-682
Nonlinear Dynamics - In this article, the authors simulate and study dark and bright soliton solutions of 1D and 2D regularized long wave (RLW) models. The RLW model occurred in various fields such...  相似文献   
124.
Mejjaoli  H.  Ben Saïd  S. 《Analysis Mathematica》2021,47(3):629-663
Analysis Mathematica - We introduce and study the k-Hankel Gabor transform. We investigate the localization operators for this transform. In particular, we study their trace class properties and we...  相似文献   
125.
A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications.  相似文献   
126.
Chen  C. Y.  Kao  C. L.  Huang  S. T.  Kuo  C. E.  Song  P. L.  Li  W. J.  Hsu  L. T.  Li  H. T. 《Chemistry of Natural Compounds》2022,58(1):107-109
Chemistry of Natural Compounds -  相似文献   
127.
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   
128.
Russian Physics Journal - The process of radiative decay of a Higgs boson into a fermion-antifermion pair $$ H\Rightarrow \overline{ff}\upgamma . $$ is investigated within the framework of the...  相似文献   
129.
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   
130.
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