全文获取类型
收费全文 | 10068篇 |
免费 | 228篇 |
国内免费 | 157篇 |
专业分类
化学 | 1250篇 |
晶体学 | 64篇 |
力学 | 51篇 |
综合类 | 17篇 |
数学 | 8203篇 |
物理学 | 868篇 |
出版年
2024年 | 6篇 |
2023年 | 35篇 |
2022年 | 43篇 |
2021年 | 54篇 |
2020年 | 68篇 |
2019年 | 224篇 |
2018年 | 208篇 |
2017年 | 115篇 |
2016年 | 101篇 |
2015年 | 140篇 |
2014年 | 275篇 |
2013年 | 513篇 |
2012年 | 312篇 |
2011年 | 618篇 |
2010年 | 539篇 |
2009年 | 650篇 |
2008年 | 671篇 |
2007年 | 767篇 |
2006年 | 573篇 |
2005年 | 370篇 |
2004年 | 304篇 |
2003年 | 318篇 |
2002年 | 266篇 |
2001年 | 186篇 |
2000年 | 200篇 |
1999年 | 254篇 |
1998年 | 252篇 |
1997年 | 211篇 |
1996年 | 227篇 |
1995年 | 272篇 |
1994年 | 216篇 |
1993年 | 209篇 |
1992年 | 183篇 |
1991年 | 99篇 |
1990年 | 101篇 |
1989年 | 118篇 |
1988年 | 65篇 |
1987年 | 58篇 |
1986年 | 58篇 |
1985年 | 91篇 |
1984年 | 93篇 |
1983年 | 62篇 |
1982年 | 84篇 |
1981年 | 53篇 |
1980年 | 43篇 |
1979年 | 43篇 |
1978年 | 49篇 |
1977年 | 21篇 |
1976年 | 18篇 |
1975年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Summary. This paper introduces and analyzes the convergence properties of a method that computes an approximation to the invariant
subspace associated with a group of eigenvalues of a large not necessarily diagonalizable matrix. The method belongs to the
family of projection type methods. At each step, it refines the approximate invariant subspace using a linearized Riccati's
equation which turns out to be the block analogue of the correction used in the Jacobi-Davidson method. The analysis conducted
in this paper shows that the method converges at a rate quasi-quadratic provided that the approximate invariant subspace is
close to the exact one. The implementation of the method based on multigrid techniques is also discussed and numerical experiments
are reported.
Received June 15, 2000 / Revised version received January 22, 2001 / Published online October 17, 2001 相似文献
72.
Jaana Eloranta 《BIT Numerical Mathematics》1991,31(4):576-590
Labeled transition systems (lts) provide an operational semantics for many specification languages. In order to abstract unrelevant details of lts's, manybehavioural equivalences have been defined; here observation equivalence is considered. We are interested in the following problem:Given a finite lts, which is the minimal observation equivalent lts corresponding to it? It is well known that the number of states of an lts can be minimized by applying arelational coarsest partition algorithm. However, the obtained lts is not unique (up to the renaming of the states): for an lts there may exist several observation equivalent lts's which have the minimal number of states but varying number of transitions. In this paper we show how the number of transitions can be minimized, obtaining a unique lts. 相似文献
73.
74.
Yuri Borovskikh 《Acta Appl Math》1994,35(3):213-298
U-statistics in Banach spaces are considered and thoroughly investigated. The martingale structure, estimates of moments, the law of large numbers, the central limit theorem, the invariance principle, estimates of the rate of convergence, and large deviations are established 相似文献
75.
76.
Maengseok Noh 《Journal of multivariate analysis》2007,98(5):896-915
The restricted maximum likelihood (REML) procedure is useful for inferences about variance components in mixed linear models. However, its extension to hierarchical generalized linear models (HGLMs) is often hampered by analytically intractable integrals. Numerical integration such as Gauss-Hermite quadrature (GHQ) is generally not recommended when the dimensionality of the integral is high. With binary data various extensions of the REML method have been suggested, but they have had unsatisfactory biases in estimation. In this paper we propose a statistically and computationally efficient REML procedure for the analysis of binary data, which is applicable over a wide class of models and design structures. We propose a bias-correction method for models such as binary matched pairs and discuss how the REML estimating equations for mixed linear models can be modified to implement more general models. 相似文献
77.
In this paper we design a fast new algorithm for reducing an N × N quasiseparable matrix to upper Hessenberg form via a sequence of N − 2 unitary transformations. The new reduction is especially useful when it is followed by the QR algorithm to obtain a complete set of eigenvalues of the original matrix. In particular, it is shown that in a number of cases some recently devised fast adaptations of the QR method for quasiseparable matrices can benefit from using the proposed reduction as a preprocessing step, yielding lower cost and a simplification of implementation. 相似文献
78.
We investigate differential operators and their compatibility with subgroups of SL2n(R). In particular, we construct Rankin-Cohen brackets for Hilbert modular forms, and more generally, multilinear differential operators on the space of Hilbert modular forms. As an application, we explicitly determine the Rankin-Cohen bracket of a Hilbert-Eisenstein series and an arbitrary Hilbert modular form. We use this result to compute the Petersson inner product of such a bracket and a Hilbert modular cusp form. 相似文献
79.
Pavel Shumyatsky 《Monatshefte für Mathematik》2007,152(2):169-175
The following theorem is proved. Let n be a positive integer and q a power of a prime p. There exists a number m = m(n, q) depending only on n and q such that if G is any residually finite group satisfying the identity ([x
1,n
y
1] ⋯ [x
m,n
y
m
])q ≡ 1, then the verbal subgroup of G corresponding to the nth Engel word is locally finite. 相似文献
80.
Brian A. Hagler 《Linear algebra and its applications》2007,422(1):100-118
Definitions, theorems and examples are established for a general model of Laurent polynomial spaces and ordered orthogonal Laurent polynomial sequences, ordered with respect to ordered bases and orthogonal with respect to inner products ·=L°⊙ decomposed into transition functional ⊙ and strong moment functional, or, more generally, sample functional L couplings. Under this formulation that is shown to subsume those in the existing literature, new fundamental results are produced, including necessary and sufficient conditions for ordered OLPS to be sequences of nth numerators of continued fractions, in contrast to the classical result concerning nth denominators which is shown to hold only in special cases. 相似文献