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   112160篇
  免费   18397篇
  国内免费   13845篇
化学   79217篇
晶体学   1286篇
力学   6462篇
综合类   886篇
数学   14394篇
物理学   42157篇
  2024年   125篇
  2023年   2104篇
  2022年   2502篇
  2021年   3685篇
  2020年   4435篇
  2019年   4250篇
  2018年   3911篇
  2017年   3585篇
  2016年   5348篇
  2015年   5248篇
  2014年   6503篇
  2013年   8429篇
  2012年   10045篇
  2011年   10575篇
  2010年   7499篇
  2009年   7279篇
  2008年   7693篇
  2007年   6868篇
  2006年   6455篇
  2005年   5442篇
  2004年   4257篇
  2003年   3419篇
  2002年   3295篇
  2001年   2669篇
  2000年   2331篇
  1999年   2299篇
  1998年   1912篇
  1997年   1676篇
  1996年   1590篇
  1995年   1416篇
  1994年   1294篇
  1993年   1034篇
  1992年   940篇
  1991年   818篇
  1990年   680篇
  1989年   535篇
  1988年   403篇
  1987年   352篇
  1986年   341篇
  1985年   279篇
  1984年   194篇
  1983年   158篇
  1982年   127篇
  1981年   80篇
  1980年   67篇
  1979年   29篇
  1978年   36篇
  1976年   26篇
  1975年   23篇
  1957年   27篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
11.
12.
Wang  Rong  Li  Xu  Zhou  Youshi  Cao  Shuxuan  Xu  Honghao  Han  Wenjuan  Zhang  Yuxia  Liu  Junhai 《Journal of Russian Laser Research》2022,43(4):476-481
Journal of Russian Laser Research - We demonstrate a passively-mode-locked Pr3+: LuLiF4 laser operated at the 604 nm orange wave-length, using monolayer graphene as a saturable absorber. The...  相似文献   
13.
14.
Li  Zhixiang  Zhao  Zhen  Liu  Caishan  Wang  Qingyun 《应用数学和力学(英文版)》2021,42(11):1571-1580
Applied Mathematics and Mechanics - Spiral springs have a wide range of applications in various fields. As a result of the complexity of friction, few theoretical analyses of spring belts under...  相似文献   
15.
16.
Li  Mingjun  Zhu  Li 《应用数学和力学(英文版)》2021,42(8):1171-1182
This study is to numerically test the interfacial instability of ferrofluid flow under the presence of a vacuum magnetic field. The ferrofluid parabolized stability equations(PSEs) are derived from the ferrofluid stability equations and the Rosensweig equations, and the characteristic values of the ferrofluid PSEs are given to describe the ellipticity of ferrofluid flow. Three numerical models representing specific cases considering with/without a vacuum magnetic field or viscosity are created to mathematically examine the interfacial instability by the computation of characteristic values. Numerical investigation shows strong dependence of the basic characteristic of ferrofluid Rayleigh-Taylor instability(RTI) on viscosity of ferrofluid and independence of the vacuum magnetic field.For the shock wave striking helium bubble, the magnetic field is not able to trigger the symmetry breaking of bubble but change the speed of the bubble movement. In the process of droplet formation from a submerged orifice, the collision between the droplet and the liquid surface causes symmetry breaking. Both the viscosity and the magnetic field exacerbate symmetry breaking. The computational results agree with the published experimental results.  相似文献   
17.
International Journal of Theoretical Physics - Quantum coherence, coming from quantum superposition, occupies a significant position in the field of physics. We put forward a lower bound of the...  相似文献   
18.
Huang  Renpei  Chen  Li  Yuan  Xiaoru 《显形杂志》2021,24(2):317-330
Journal of Visualization - Forecast calibration methods based on historical similar atmospheric state are effective means weather forecast accuracy. Conventional approaches search similar forecasts...  相似文献   
19.
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   
20.
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