全文获取类型
收费全文 | 10379篇 |
免费 | 251篇 |
国内免费 | 30篇 |
专业分类
化学 | 6865篇 |
晶体学 | 96篇 |
力学 | 214篇 |
数学 | 1257篇 |
物理学 | 2228篇 |
出版年
2021年 | 84篇 |
2020年 | 117篇 |
2019年 | 99篇 |
2018年 | 77篇 |
2016年 | 230篇 |
2015年 | 190篇 |
2014年 | 189篇 |
2013年 | 406篇 |
2012年 | 419篇 |
2011年 | 493篇 |
2010年 | 270篇 |
2009年 | 284篇 |
2008年 | 452篇 |
2007年 | 413篇 |
2006年 | 416篇 |
2005年 | 389篇 |
2004年 | 340篇 |
2003年 | 292篇 |
2002年 | 278篇 |
2001年 | 215篇 |
2000年 | 210篇 |
1999年 | 146篇 |
1998年 | 136篇 |
1997年 | 166篇 |
1996年 | 169篇 |
1995年 | 163篇 |
1994年 | 157篇 |
1993年 | 169篇 |
1992年 | 126篇 |
1991年 | 134篇 |
1990年 | 103篇 |
1989年 | 128篇 |
1988年 | 140篇 |
1987年 | 115篇 |
1986年 | 110篇 |
1985年 | 170篇 |
1984年 | 135篇 |
1983年 | 117篇 |
1982年 | 134篇 |
1981年 | 145篇 |
1980年 | 86篇 |
1979年 | 109篇 |
1978年 | 96篇 |
1977年 | 104篇 |
1976年 | 105篇 |
1975年 | 106篇 |
1973年 | 95篇 |
1968年 | 94篇 |
1967年 | 114篇 |
1966年 | 104篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Handling industrial powders leads to dust emissions. These emissions tend to generate human diseases or cause other environmental effects. A multitude of apparatus has been developed to estimate this dustiness behaviour of powders. Two of these well-known methods are presented and compared with each other. A third recently developed method is also introduced. 相似文献
992.
993.
994.
We calculate the quantum phase transition for a homogeneous Bose gas in the plane of s‐wave scattering length as and temperature T. This is done by improving a one‐loop result near the interaction‐free Bose‐Einstein critical temperature Tc(0) with the help of recent high‐loop results on the shift of the critical temperature due to a weak atomic repulsion based on variational perturbation theory. The quantum phase diagram shows a nose above Tc(0), so that we predict the existence of a reentrant transition above Tc(0), where an increasing repulsion leads to the formation of a condensate. 相似文献
995.
Recently, Freund and Nachtigal proposed the quasi-minimal residual algorithm (QMR) for solving general nonsingular non-Hermitian linear systems. The method is based on the Lanczos process, and thus it involves matrix—vector products with both the coefficient matrix of the linear system and its transpose. Freund developed a variant of QMR, the transpose-free QMR algorithm (TFQMR), that only requires products with the coefficient matrix. In this paper, the use of QMR and TFQMR for solving singular systems is explored. First, a convergence result for the general class of Krylov-subspace methods applied to singular systems is presented. Then, it is shown that QMR and TFQMR both converge for consistent singular linear systems with coefficient matrices of index 1. Singular systems of this type arise in Markov chain modeling. For this particular application, numerical experiments are reported. 相似文献
996.
997.
Gunther Schmidt 《Numerische Mathematik》1986,50(3):337-352
Summary This paper analyses the convergence of spline collocation methods for singular integro-differential equations over the interval (0.1). As trial functions we utilize smooth polynomial splines the degree of which coincides with the order of the equation. Depending on the choice of collocation points we obtain sufficient and even necessary conditions for the convergence in sobolev norms. We give asymptotic error estimates and some numerical results. 相似文献
998.
999.
1000.
Within a scalar model theory of gravity, where the interaction between particles is given by the half-retarded plus half-advanced solution of the scalar wave equation, we consider an N-body problem: We investigate configurations of N particles which form an equilateral N angle and are in helical motion about their common center. We prove that there exists a unique equilibrium configuration and compute the equilibrium radius explicitly in a post-Newtonian expansion. 相似文献