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   162275篇
  免费   19331篇
  国内免费   10879篇
化学   116128篇
晶体学   2138篇
力学   7837篇
综合类   722篇
数学   17907篇
物理学   47753篇
  2023年   1246篇
  2022年   2831篇
  2021年   3273篇
  2020年   4507篇
  2019年   5860篇
  2018年   4804篇
  2017年   4577篇
  2016年   7887篇
  2015年   7003篇
  2014年   8389篇
  2013年   10871篇
  2012年   10533篇
  2011年   10494篇
  2010年   9181篇
  2009年   9137篇
  2008年   8997篇
  2007年   8037篇
  2006年   7226篇
  2005年   6481篇
  2004年   5468篇
  2003年   4823篇
  2002年   5628篇
  2001年   4624篇
  2000年   3949篇
  1999年   2609篇
  1998年   2068篇
  1997年   1803篇
  1996年   1725篇
  1995年   1475篇
  1994年   1482篇
  1993年   1354篇
  1992年   1283篇
  1991年   1335篇
  1990年   1291篇
  1989年   1186篇
  1988年   1023篇
  1987年   999篇
  1986年   971篇
  1985年   992篇
  1984年   951篇
  1983年   860篇
  1982年   829篇
  1979年   813篇
  1978年   817篇
  1977年   809篇
  1976年   921篇
  1975年   813篇
  1974年   849篇
  1973年   849篇
  1972年   756篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Knyazev  Yu. V.  Kazak  N. V.  Gavrichkov  V. A.  Polukeev  S. I.  Ovchinnikov  S. G. 《JETP Letters》2022,116(8):567-573
JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and...  相似文献   
12.
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs.  相似文献   
13.
14.
Russian Physics Journal - The temperature dependences of the linear dielectric permittivity ε′ and the third harmonic coefficient γ3ω for nanocomposites obtained by embedding a...  相似文献   
15.
Technical Physics - Taking damping into account in the problems of structural dynamics is an important and nontrivial problem. Its complexity is primarily determined by the required specification...  相似文献   
16.
Theoretical and Mathematical Physics - We consider three one-dimensional superconducting structures: 1) the one with $$p$$ -wave superconductivity; 2) the main experimental model of a nanowire with...  相似文献   
17.
18.
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   
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.
Physics of the Solid State - The interference of excited and received by current antennae magnetoelastic waves counterpropagating in an yttrium iron garnet film is experimentally studied. It is...  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