全文获取类型
收费全文 | 18457篇 |
免费 | 552篇 |
国内免费 | 370篇 |
专业分类
化学 | 2336篇 |
晶体学 | 77篇 |
力学 | 308篇 |
综合类 | 50篇 |
数学 | 15029篇 |
物理学 | 1579篇 |
出版年
2023年 | 50篇 |
2022年 | 139篇 |
2021年 | 130篇 |
2020年 | 133篇 |
2019年 | 481篇 |
2018年 | 544篇 |
2017年 | 266篇 |
2016年 | 238篇 |
2015年 | 282篇 |
2014年 | 568篇 |
2013年 | 1108篇 |
2012年 | 683篇 |
2011年 | 1253篇 |
2010年 | 940篇 |
2009年 | 1238篇 |
2008年 | 1314篇 |
2007年 | 1439篇 |
2006年 | 1078篇 |
2005年 | 775篇 |
2004年 | 617篇 |
2003年 | 548篇 |
2002年 | 400篇 |
2001年 | 369篇 |
2000年 | 372篇 |
1999年 | 433篇 |
1998年 | 371篇 |
1997年 | 305篇 |
1996年 | 344篇 |
1995年 | 343篇 |
1994年 | 355篇 |
1993年 | 305篇 |
1992年 | 263篇 |
1991年 | 162篇 |
1990年 | 180篇 |
1989年 | 166篇 |
1988年 | 118篇 |
1987年 | 117篇 |
1986年 | 90篇 |
1985年 | 140篇 |
1984年 | 112篇 |
1983年 | 66篇 |
1982年 | 111篇 |
1981年 | 84篇 |
1980年 | 78篇 |
1979年 | 44篇 |
1978年 | 65篇 |
1977年 | 59篇 |
1976年 | 46篇 |
1975年 | 19篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
61.
Marianna A. Shubov 《Integral Equations and Operator Theory》1997,28(3):358-372
We announce a series of results on the spectral analysis for a class of nonselfadjoint opeators, which are the dynamics generators for the systems governed by hyperbolic equations containing dissipative terms. Two such equations are considered: the equation of nonhomogeneous damped string and the 3-dimensional damped wave equation with spacially nonhomogeneous spherically symmetric coefficients. Nonselfadjoint boundary conditions are imposed at the ends of a finite interval or on a sphere centered at the origin respectively. Our main result is the fact the aforementioned operators are spectral in the sense of N. Dunford. The result follows from the fact that the systems of root vectors of the above operators form Riesz bases in the corresponding energy spaces. We also give asymptotics of the spectra and state the Riesz basis property results for the nonselfadjoint operator pencils associated with these operators. 相似文献
62.
Kevin Houston 《Inventiones Mathematicae》2002,147(3):471-485
The disentanglement of certain augmentations is shown to be the topological join of a disentanglement and a Milnor fibre.
The kth disentanglement of a finite map is defined and for corank 1 maps from ℂ
n
to ℂ
n
+1 it is shown that they are homotopically equivalent to a wedge of spheres. Applications to the Mond conjecture are given.
Oblatum 24-VII-2000 & 5-VII-2001?Published online: 12 October 2001 相似文献
63.
64.
Sans résumé
相似文献
相似文献
65.
Jing-song Huang 《Mathematische Annalen》1993,297(1):309-324
Supported in part by NSF Grant DMS-8610730 相似文献
66.
Y.P. Venkata Subbaiah 《Applied Surface Science》2006,253(5):2409-2415
ZnS films have been deposited on glass substrates by close-spaced evaporation (CSE) technique. The films were grown at different temperatures in the range, 200-350 °C. The layers have been characterized with X-ray diffractometer (XRD), atomic force microscope (AFM), energy dispersive analysis of X-rays (EDAX) and optical spectrophotometer to evaluate the quality of the layers for photovoltaic applications. The studies showed that the optimum substrate temperature for the growth of ZnS layers was 300 °C. The films grown at these temperatures exhibited cubic structure with nearly stoichiometric composition. The AFM data revealed that the films had nano-sized grains with a grain size of ∼40 nm. The optical studies exhibited direct allowed transition with an energy band gap of 3.61 eV. The other structural and optical parameters such as lattice stress, dislocation density, refractive index and extinction coefficient were also evaluated. The temperature-dependent conductivity measured in the range, 303-523 K showed a change in the conduction mechanism at 120 °C. The activation energy values evaluated using the temperature dependence of electrical conductivity are 7 and 29 meV at low and high temperature regions, respectively. 相似文献
67.
Pascal Cherrier 《Bulletin des Sciences Mathématiques》2007,131(4):375-396
We study a parabolic version of a system of Von Karman type on a compact Kähler manifold of arbitrary dimension. We provide local in time regular solutions, which can be extended to global bounded ones if the data of the problem are small. 相似文献
68.
Daisuke Kishimoto 《Topology and its Applications》2007,154(7):1465-1469
By calculating certain generalized cohomology theory, lower bounds for the L-S category of quaternionic Stiefel manifolds are given. 相似文献
69.
Let Λ be a smooth Lagrangian submanifold of a complex symplectic manifold X. We construct twisted simple holonomic modules along Λ in the stack of deformation-quantization modules on X. 相似文献
70.