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   119753篇
  免费   1825篇
  国内免费   1240篇
化学   46109篇
晶体学   1512篇
力学   8661篇
综合类   40篇
数学   36051篇
物理学   30445篇
  2022年   535篇
  2021年   568篇
  2020年   548篇
  2019年   583篇
  2018年   11050篇
  2017年   10796篇
  2016年   6983篇
  2015年   1553篇
  2014年   1338篇
  2013年   2283篇
  2012年   5762篇
  2011年   12797篇
  2010年   7271篇
  2009年   7620篇
  2008年   8411篇
  2007年   10521篇
  2006年   1924篇
  2005年   2740篇
  2004年   2856篇
  2003年   3129篇
  2002年   2075篇
  2001年   1724篇
  2000年   1387篇
  1999年   1117篇
  1998年   931篇
  1997年   845篇
  1996年   821篇
  1995年   699篇
  1994年   621篇
  1993年   551篇
  1992年   586篇
  1991年   613篇
  1990年   561篇
  1989年   513篇
  1988年   533篇
  1987年   515篇
  1986年   449篇
  1985年   504篇
  1984年   521篇
  1983年   398篇
  1982年   432篇
  1981年   415篇
  1980年   366篇
  1979年   445篇
  1978年   412篇
  1977年   413篇
  1976年   407篇
  1975年   358篇
  1974年   333篇
  1973年   364篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Kinetics and Catalysis - A new ruthenium(II) cage complex with polar terminal groups in the apical substituents has been synthesized; the molecular design of the complex contributes to the...  相似文献   
2.
Fan  K.  Lu  R. S.  Liang  K. K.  Hou  Z. C. 《High Energy Chemistry》2022,56(4):264-269
High Energy Chemistry - Modification of Polyvinylidene fluoride (PVDF) by radiation grafting is a research hotspot in recent years. In this study, the monomer 2-Hydroxyethyl methacrylate (HEMA) was...  相似文献   
3.
Siberian Mathematical Journal - A lattice homomorphism between quasi-Banach lattices is known to be compact if and only if it is a sum of a series of rank one lattice...  相似文献   
4.
We consider concentrated vorticities for the Euler equation on a smooth domain Ω?R2 in the form of
ω=j=1NωjχΩj,|Ωj|=πrj2,Ωjωjdμ=μj0,
supported on well-separated vortical domains Ωj, j=1,,N, of small diameters O(rj). A conformal mapping framework is set up to study this free boundary problem with Ωj being part of unknowns. For any given vorticities μ1,,μN and small r1,,rNR+, through a perturbation approach, we obtain such piecewise constant steady vortex patches as well as piecewise smooth Lipschitz steady vorticities, both concentrated near non-degenerate critical configurations of the Kirchhoff–Routh Hamiltonian function. When vortex patch evolution is considered as the boundary dynamics of ?Ωj, through an invariant subspace decomposition, it is also proved that the spectral/linear stability of such steady vortex patches is largely determined by that of the 2N-dimensional linearized point vortex dynamics, while the motion is highly oscillatory in the 2N-codim directions corresponding to the vortical domain shapes.  相似文献   
5.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers.  相似文献   
6.
7.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.  相似文献   
8.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant.  相似文献   
9.
10.
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser.  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