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   17347篇
  免费   3026篇
  国内免费   3136篇
化学   13952篇
晶体学   314篇
力学   769篇
综合类   216篇
数学   1717篇
物理学   6541篇
  2024年   42篇
  2023年   330篇
  2022年   623篇
  2021年   680篇
  2020年   735篇
  2019年   742篇
  2018年   645篇
  2017年   713篇
  2016年   908篇
  2015年   963篇
  2014年   1209篇
  2013年   1465篇
  2012年   1802篇
  2011年   1859篇
  2010年   1375篇
  2009年   1262篇
  2008年   1360篇
  2007年   1193篇
  2006年   1099篇
  2005年   809篇
  2004年   578篇
  2003年   462篇
  2002年   514篇
  2001年   454篇
  2000年   301篇
  1999年   299篇
  1998年   188篇
  1997年   164篇
  1996年   119篇
  1995年   105篇
  1994年   86篇
  1993年   93篇
  1992年   58篇
  1991年   47篇
  1990年   30篇
  1989年   47篇
  1988年   25篇
  1987年   28篇
  1986年   27篇
  1985年   26篇
  1984年   9篇
  1983年   6篇
  1982年   5篇
  1981年   3篇
  1980年   2篇
  1976年   2篇
  1974年   2篇
  1973年   4篇
  1959年   2篇
  1957年   4篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
2.
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   
3.
International Journal of Theoretical Physics - The Majorana representation, which provides an intuitive way to represent the quantum state by stars on the Bloch sphere, has drawn considerable...  相似文献   
4.
5.
Journal of Sol-Gel Science and Technology - A novel gas sensing material, La–Y co-doped TiO2 nanoparticles, was synthesized by sol–gel method and applied to detect organic pollutants...  相似文献   
6.
7.
JPC – Journal of Planar Chromatography – Modern TLC - A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of...  相似文献   
8.
The implementation of covalent adaptable networks (CANs) in general resin system is becoming attractive. In this work, we propose a simple post-curing strategy based on the core-shell structured acrylate latex for the achievement on both the improved general performance and the CANs characteristics in latex films. The building to the CANs was relied on the introduction of 4,4′-diaminophenyl disulfide as the curing agent, which cured the acetoacetoxy decorated shell polymer through the ketoamine reaction. The metathesis reaction of aromatic disulfides in the crosslinking segments enabled the thermally induced dynamic behavior of the network as revealed in the stress relaxation tests by comparison with other diamine crosslinking agents without the incorporation of disulfide. The synergism of the dynamic crosslinking of the shell polymer and static crosslinking in the core polymer contributed to the improved mechanical strength (15 MPa, strain% = 250%) and the suppressed water adsorption (~1% in 24 h of soaking) of the latex film, which exhibited above 90% of recovery in both strength and strain from a cut-off film damage within 1 h at 80°C. Moreover, the cured latex film could be recycled, and 75% of the mechanical performance was regained after three fragmentation-hot-pressing cycles. These, in addition with the feasible and environmental friendly characteristics, suggest a sustainable paradigm toward the smart thermosetting latex polymers.  相似文献   
9.
10.
For the orthosymplectic Lie superalgebra ◂⋅▸OSP(2,2), we choose a set of basis matrices. A linear combination of those basis matrices presents a spatial spectral matrix. The compatible condition of the spatial part and the corresponding temporal parts of the spectral problem leads to a generalized super AKNS (GSAKNS) hierarchy. By making use of the supertrace identity, the obtained GSAKNS hierarchy can be written as the super bi-Hamiltonian structures.  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