全文获取类型
收费全文 | 20678篇 |
免费 | 2438篇 |
国内免费 | 2122篇 |
专业分类
化学 | 2330篇 |
晶体学 | 37篇 |
力学 | 1829篇 |
综合类 | 508篇 |
数学 | 13641篇 |
物理学 | 6893篇 |
出版年
2024年 | 31篇 |
2023年 | 171篇 |
2022年 | 350篇 |
2021年 | 379篇 |
2020年 | 433篇 |
2019年 | 441篇 |
2018年 | 475篇 |
2017年 | 605篇 |
2016年 | 665篇 |
2015年 | 528篇 |
2014年 | 1052篇 |
2013年 | 1346篇 |
2012年 | 1094篇 |
2011年 | 1319篇 |
2010年 | 1153篇 |
2009年 | 1422篇 |
2008年 | 1394篇 |
2007年 | 1478篇 |
2006年 | 1332篇 |
2005年 | 1265篇 |
2004年 | 1062篇 |
2003年 | 942篇 |
2002年 | 812篇 |
2001年 | 756篇 |
2000年 | 683篇 |
1999年 | 587篇 |
1998年 | 538篇 |
1997年 | 501篇 |
1996年 | 366篇 |
1995年 | 297篇 |
1994年 | 247篇 |
1993年 | 185篇 |
1992年 | 158篇 |
1991年 | 127篇 |
1990年 | 139篇 |
1989年 | 101篇 |
1988年 | 85篇 |
1987年 | 78篇 |
1986年 | 68篇 |
1985年 | 84篇 |
1984年 | 69篇 |
1983年 | 46篇 |
1982年 | 64篇 |
1981年 | 59篇 |
1980年 | 40篇 |
1979年 | 36篇 |
1978年 | 32篇 |
1977年 | 30篇 |
1976年 | 30篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Finitely generated linear semigroups over a field K that have intermediate growth are considered. New classes of such semigroups are found and a conjecture on the equivalence of the subexponential growth of a finitely generated linear semigroup S and the nonexistence of free noncommutative subsemigroups in S, or equivalently the existence of a nontrivial identity satisfied in S, is stated. This ‘growth alternative’ conjecture is proved for linear semigroups of degree 2, 3 or 4. Certain results supporting the general conjecture are obtained. As the main tool, a new combinatorial property of groups is introduced and studied. 相似文献
52.
S. V. Tyshkevich 《Mathematical Notes》2007,81(5-6):851-853
53.
D.L. Skuratov Yu.L. Ratis I.A. Selezneva J. Pérez P. Fernández de Córdoba J.F. Urchueguía 《Applied Mathematical Modelling》2007
This paper deals with modelling the workpiece temperature field produced during the grinding process. The proposed model is given in terms of a two-dimensional boundary-value problem where the interdependence among the grinding wheel, the workpiece and the coolant is described by two variable functions in the boundary condition. An explicit integral form solution is constructed using the Laplace and Fourier transforms and the Green’s function method. 相似文献
54.
Wilson A. Cañas-Marín Julián D. Ortiz-Arango Uriel E. Guerrero-Aconcha Claudia P. Soto-Tavera 《Fluid Phase Equilibria》2007
The ability of Soave–Redlich–Kwong cubic equation of state (SRK EoS) to predict densities and thermodynamic derivative properties such as thermal expansivity, isothermal compressibility, calorific capacity, and Joule–Thompson coefficients, for two gas condensates over a wide range of pressures (up to 110 MPa) was studied. The predictions of the EoS were compared to Monte Carlo simulation data obtained by Lagache et al. [M.H. Lagache, P. Ungerer, A. Boutin, Fluid Phase Equilibr. 220 (2004) 221]. Two completely different alpha functions for the SRK EoS attractive term were used and their respective effects on the predictions of such properties were analyzed. Also, two different forms of the crossed terms of the attractive parameter, aij, and three expressions of the crossed terms of the repulsive parameter, bij, were combined in different ways, and predictions were carried out. Little sensitivity of the properties on the chosen alpha function, except for the calorific capacities, was found in the systems studied. The most commonly used combination rules to model phase behavior of reservoir fluids, i.e. geometric and arithmetic forms of aij and bij, respectively, predicted very deficient results for these fluids at extreme conditions, specially for density calculations. 相似文献
55.
Roderich Tumulka 《Foundations of Physics》2007,37(2):186-197
In a recent paper Conway and Kochen, Found. Phys. 36, 2006, claim to have established that theories of the Ghirardi-Rimini-Weber
(RW) type, i.e., of spontaneous wave function collapse, cannot be made relativistic. On the other hand, relativistic GRW-type
theories have already been presented, in my recent paper, J. Stat. Phys. 125, 2006, and by Dowker and Henson, J. Stat. Phys.
115, 2004. Here, I elucidate why these are not excluded by the arguments of Conway and Kochen.
相似文献
56.
57.
Differentiation of functions w.r.t. finite atomless measures with compact support on the real line is introduced. The related harmonic calculus is similar to that of the classical Lebesgue case. As an application we obtain the Weyl exponent for the spectral asymptotics of the Laplacians w.r.t. linear Cantor-type measures with arbitrary weights. 相似文献
58.
59.
In this paper, the deconvolution of SIMS profiles analysed at very low primary energy (0.5 keV/O2+) is addressed. The depth resolution function (DRF) of the SIMS analysis in presence of roughness is established and a deconvolution procedure is implemented without or in presence of roughness on samples containing delta-doped layers of boron in silicon. It is shown that the deconvolution procedure can lead to a great improvement of the full width at half maximum (FWHM) of the measured peaks in the case where no roughness in detected in the crater bottom. In the case where it is present, the conditions required to use a deconvolution procedure are discussed, and the deconvolution is implemented using precise and restrictive assumptions. 相似文献
60.
Differential inequality method, bounding function method and topological degree are applied to obtain the existence criterions of at least one solution for the general fourth-order differential equations under nonlinear boundary conditions, and many existing results are complemented. 相似文献