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   1284043篇
  免费   33178篇
  国内免费   10952篇
化学   635642篇
晶体学   20168篇
力学   74725篇
综合类   417篇
数学   239547篇
物理学   357674篇
  2021年   14125篇
  2020年   16521篇
  2019年   16790篇
  2016年   27832篇
  2015年   21446篇
  2014年   31460篇
  2013年   75643篇
  2012年   35746篇
  2011年   29752篇
  2010年   36040篇
  2009年   39137篇
  2008年   29848篇
  2007年   24413篇
  2006年   32825篇
  2005年   23914篇
  2004年   26285篇
  2003年   25522篇
  2002年   27236篇
  2001年   24732篇
  2000年   22684篇
  1999年   21724篇
  1998年   20893篇
  1997年   20889篇
  1996年   21122篇
  1995年   19265篇
  1994年   18637篇
  1993年   18113篇
  1992年   17593篇
  1991年   17910篇
  1990年   17138篇
  1989年   17239篇
  1988年   16747篇
  1987年   16776篇
  1986年   15659篇
  1985年   22124篇
  1984年   23497篇
  1983年   19772篇
  1982年   21511篇
  1981年   20758篇
  1980年   20091篇
  1979年   20090篇
  1978年   21513篇
  1977年   21057篇
  1976年   20715篇
  1975年   19383篇
  1974年   19011篇
  1973年   19489篇
  1972年   14015篇
  1968年   11889篇
  1967年   12269篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
David Hull     
Journal of Optimization Theory and Applications -  相似文献   
93.
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   
94.
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   
95.
Crystallography Reports - The recombinant С-terminal fragment of myomesin-2 was purified to a homogeneous state. The crystallization conditions for the С-terminal fragment of myomesin-2...  相似文献   
96.
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   
97.
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   
98.
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   
99.
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   
100.
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   
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