全文获取类型
收费全文 | 997篇 |
免费 | 50篇 |
国内免费 | 96篇 |
专业分类
化学 | 80篇 |
力学 | 8篇 |
综合类 | 23篇 |
数学 | 914篇 |
物理学 | 118篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 19篇 |
2021年 | 14篇 |
2020年 | 28篇 |
2019年 | 21篇 |
2018年 | 20篇 |
2017年 | 22篇 |
2016年 | 31篇 |
2015年 | 9篇 |
2014年 | 42篇 |
2013年 | 91篇 |
2012年 | 24篇 |
2011年 | 47篇 |
2010年 | 32篇 |
2009年 | 64篇 |
2008年 | 70篇 |
2007年 | 78篇 |
2006年 | 63篇 |
2005年 | 53篇 |
2004年 | 48篇 |
2003年 | 42篇 |
2002年 | 51篇 |
2001年 | 39篇 |
2000年 | 35篇 |
1999年 | 36篇 |
1998年 | 33篇 |
1997年 | 17篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1970年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有1143条查询结果,搜索用时 15 毫秒
61.
证明了强平稳正相协列乘积和的重对数律与不同分布正相协列乘积和的强大数律,指出了部分和服从强大数律但乘积和未必服从强大数律这一事实,并讨论了定理2中一个条件的必要性. 相似文献
62.
Summary For P∈ F2[z] with P(0)=1 and deg(P)≧ 1, let A =A(P) be the unique subset of N (cf. [9]) such that Σn≧0 p(A,n)zn ≡ P(z) mod 2, where p(A,n) is the number of partitions of n with parts in A. To determine the elements of the set A, it is important to consider the sequence σ(A,n) = Σ d|n, d∈A d, namely, the periodicity of the sequences (σ(A,2kn) mod 2k+1)n≧1 for all k ≧ 0 which was proved in [3]. In this paper, the values of such sequences will be given in terms of orbits. Moreover, a formula
to σ(A,2kn) mod 2k+1 will be established, from which it will be shown that the weight σ(A1,2kzi) mod 2k+1 on the orbit <InlineEquation ID=IE"1"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"2"><EquationSource Format="TEX"><![CDATA[$]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>z_i$
is moved on some other orbit zj when A1 is replaced by A2 with A1= A(P1) and A2= A(P2) P1 and P2 being irreducible in F2[z] of the same odd order. 相似文献
63.
In this paper some decompositions of Cauchy polynomials, Ferrers-Jackson polynomials and polynomials of the form x
2n
+ y
2n
, n ∈ ℕ, are studied. These decompositions are used to generate the identities for powers of Fibonacci and Lucas numbers as well
as for powers of the so called conjugate recurrence sequences. Also, some new identities for Chebyshev polynomials of the
first kind are presented here. 相似文献
64.
We study the limit behavior of the canonical (i.e., degenerate) von Mises statistics based on samples from a sequence of weakly dependent stationary observations satisfying the ψ-mixing condition. The corresponding limit distributions are defined by the multiple stochastic integrals of nonrandom functions with respect to the nonorthogonal Hilbert noises generated by Gaussian processes with nonorthogonal increments. 相似文献
65.
We continue the study of the linear complexity of binary sequences, independently introduced by Sidel’nikov and Lempel, Cohn,
and Eastman. These investigations were originated by Helleseth and Yang and extended by Kyureghyan and Pott. We determine
the exact linear complexity of several families of these sequences using well-known results on cyclotomic numbers. Moreover,
we prove a general lower bound on the linear complexity profile for all of these sequences. 相似文献
66.
Ryma Imene
Rahla Stefano Serra‐Capizzano Cristina Tablino‐Possio 《Numerical Linear Algebra with Applications》2020,27(4)
In the present article, we consider a class of elliptic partial differential equations with Dirichlet boundary conditions and where the operator is div(?a( x )?·), with a continuous and positive over , Ω being an open and bounded subset of , d≥1. For the numerical approximation, we consider the classical Finite Elements, in the case of Friedrichs–Keller triangulations, leading, as usual, to sequences of matrices of increasing size. The new results concern the spectral analysis of the resulting matrix‐sequences in the direction of the global distribution in the Weyl sense, with a concise overview on localization, clustering, extremal eigenvalues, and asymptotic conditioning. We study in detail the case of constant coefficients on Ω=(0,1)2 and we give a brief account in the more involved case of variable coefficients and more general domains. Tools are drawn from the Toeplitz technology and from the rather new theory of Generalized Locally Toeplitz sequences. Numerical results are shown for a practical evidence of the theoretical findings. 相似文献
67.
68.
69.
Nguyen H. V. Hu'ng 《Transactions of the American Mathematical Society》2001,353(11):4447-4460
Let be Singer's invariant-theoretic model of the dual of the lambda algebra with , where denotes the mod 2 Steenrod algebra. We prove that the inclusion of the Dickson algebra, , into is a chain-level representation of the Lannes-Zarati dual homomorphism
The Lannes-Zarati homomorphisms themselves, , correspond to an associated graded of the Hurewicz map
Based on this result, we discuss some algebraic versions of the classical conjecture on spherical classes, which states that Only Hopf invariant one and Kervaire invariant one classes are detected by the Hurewicz homomorphism. One of these algebraic conjectures predicts that every Dickson element, i.e. element in , of positive degree represents the homology class in for 2$">.
We also show that factors through , where denotes the differential of . Therefore, the problem of determining should be of interest.
70.
Daxiong Piao 《中国科学A辑(英文版)》2001,44(9):1156-1161
In this paper, we investigate the existence and uniqueness of new almost periodic type solutions, so-called pseudo almost
periodic solutions for the systems of differential equations with piecewise constant argument by means of introducing the
notion of pseudo almost periodic vector sequences 相似文献