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   1608篇
  免费   65篇
  国内免费   7篇
化学   1331篇
晶体学   10篇
力学   14篇
数学   73篇
物理学   252篇
  2023年   16篇
  2022年   20篇
  2021年   20篇
  2020年   25篇
  2019年   26篇
  2018年   26篇
  2017年   16篇
  2016年   42篇
  2015年   33篇
  2014年   48篇
  2013年   84篇
  2012年   142篇
  2011年   111篇
  2010年   61篇
  2009年   71篇
  2008年   113篇
  2007年   122篇
  2006年   125篇
  2005年   95篇
  2004年   77篇
  2003年   59篇
  2002年   42篇
  2001年   26篇
  2000年   23篇
  1999年   12篇
  1998年   14篇
  1997年   10篇
  1996年   9篇
  1995年   13篇
  1994年   7篇
  1993年   9篇
  1992年   8篇
  1991年   9篇
  1990年   8篇
  1988年   12篇
  1986年   7篇
  1985年   16篇
  1984年   15篇
  1983年   10篇
  1982年   12篇
  1981年   8篇
  1980年   5篇
  1979年   10篇
  1978年   10篇
  1977年   7篇
  1976年   7篇
  1975年   5篇
  1974年   5篇
  1971年   6篇
  1969年   4篇
排序方式: 共有1680条查询结果,搜索用时 15 毫秒
101.
A systematic perturbation theory is developed for the ESR shift and is applied to the spin-1/2 Heisenberg antiferromagnetic chain with a general anisotropic exchange interaction. Using the Bethe ansatz technique, the resonance shift is obtained exactly for the whole range of temperature and magnetic field in the first order of the anisotropy. The obtained g shift strongly depends on magnetic fields at low temperature, showing a significant deviation from the previous classical result.  相似文献   
102.

Background  

Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language.  相似文献   
103.
104.
105.
Reactions of [Ni6(CO)12]2- (1) with CuBr2 have given rise in small yields (10%) to the first example of a close-packed copper-nickel carbonyl cluster; its formulation as [CuxNi35-x(CO)40]5- (with x=3 or 5) is based upon a low-temperature CCD X-ray crystallographic determination coupled with an elemental analysis and X-ray fluorescence measurements. This air-unstable black pentaanion (2) together with one co-crystallized bromide anion, six [NMe4]+ counterions, and one solvated acetone molecule comprise the crystallographic independent part in a monoclinic unit cell of P21/n symmetry (with Z=4). The geometrically unprecedented 35-atom hcp M(A)2M(B)3Ni30 polyhedron of pseudo-D3h symmetry consists of a central 15-atom equilateral 4M(B)3Ni12 triangle that is capped on both sides by two symmetry-related 10-atom equilateral 3M(A)Ni9 triangles. The 35-atom M(A)2M(B)3Ni30 core is encapsulated by 40 COs, whose connectivities, due to an extra CO ligand on one of the three triangular sides, reduce the pseudo D3h symmetry of the metal core to Cs. An elemental analysis via AA and X-ray fluorescence measurements resulted in Cu/Ni ratios of 3.2/31.8 and 3.7/31.3, respectively, that are consistent with the metal core being either Cu5Ni30 (i.e., M(A)=M(B)=Cu) or Cu3Ni32 (i.e., M(A)=Ni; M(B)=Cu). Several attempts to determine the actual stoichiometry of the metal core by use of electrospray FT/MS/ICR measurements were unsuccessful. The maximum metal-core diameter of 2 is ca. 0.41 nm parallel and 0.85 nm perpendicular to the principal 3-fold axis.  相似文献   
106.

A crystal base theory is introduced for the quantized enveloping algebra of the general linear Lie superalgebra , and an explicit realization of the crystal base is given in terms of semistandard tableaux.  相似文献   

107.
This paper describes a method for measuring the three-dimensional (3D) refractive-index distribution in a single cell. The method can be used to observe the distribution of cell components without fluorescence staining. The two-dimensional optical path length distributions from multiple directions are obtained by non-contact rotation of the cell. These optical path lengths are converted into the line integrals of the refractive index, and the 3D refractive-index distribution is reconstructed by means of computed tomography. The refractive-index distribution in a breast cancer cell can be measured using a phase-shifting Mach—Zehnder interferometer in conjunction with proximal two-beam optical tweezers.  相似文献   
108.
Transitions related to the spin-glass phase in Mn1−xTixSb are revisited from the nonlinear ac susceptibility. Near the tricritical point (x≈0.8), the transition between ferromagnetic and reentrant spin-glass states is sharp. At x0.8, an anomally is found slightly above the temperature of usual spin-glass freezing.  相似文献   
109.
110.
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