全文获取类型
收费全文 | 2910篇 |
免费 | 53篇 |
国内免费 | 54篇 |
专业分类
化学 | 2055篇 |
晶体学 | 18篇 |
力学 | 56篇 |
数学 | 510篇 |
物理学 | 378篇 |
出版年
2021年 | 25篇 |
2017年 | 17篇 |
2016年 | 51篇 |
2015年 | 30篇 |
2014年 | 59篇 |
2013年 | 109篇 |
2012年 | 99篇 |
2011年 | 145篇 |
2010年 | 62篇 |
2009年 | 51篇 |
2008年 | 118篇 |
2007年 | 135篇 |
2006年 | 83篇 |
2005年 | 116篇 |
2004年 | 96篇 |
2003年 | 73篇 |
2002年 | 63篇 |
2001年 | 24篇 |
2000年 | 28篇 |
1999年 | 26篇 |
1998年 | 23篇 |
1997年 | 31篇 |
1996年 | 32篇 |
1995年 | 29篇 |
1994年 | 28篇 |
1992年 | 26篇 |
1991年 | 34篇 |
1990年 | 25篇 |
1989年 | 21篇 |
1988年 | 40篇 |
1987年 | 49篇 |
1986年 | 36篇 |
1985年 | 48篇 |
1984年 | 50篇 |
1983年 | 35篇 |
1982年 | 39篇 |
1981年 | 44篇 |
1980年 | 37篇 |
1979年 | 39篇 |
1978年 | 70篇 |
1977年 | 51篇 |
1976年 | 53篇 |
1975年 | 24篇 |
1974年 | 41篇 |
1973年 | 41篇 |
1972年 | 22篇 |
1971年 | 17篇 |
1969年 | 16篇 |
1885年 | 23篇 |
1884年 | 26篇 |
排序方式: 共有3017条查询结果,搜索用时 0 毫秒
151.
Carl Johan Casselgren 《Random Structures and Algorithms》2014,44(3):317-327
Let G = G(n) be a graph on n vertices with maximum degree bounded by some absolute constant Δ. Assign to each vertex v of G a list L(v) of colors by choosing each list uniformly at random from all k‐subsets of a color set of size . Such a list assignment is called a random ‐list assignment. In this paper, we are interested in determining the asymptotic probability (as ) of the existence of a proper coloring ? of G, such that for every vertex v of G. We show, for all fixed k and growing n, that if , then the probability that G has such a proper coloring tends to 1 as . A similar result for complete graphs is also obtained: if and L is a random ‐list assignment for the complete graph Kn on n vertices, then the probability that Kn has a proper coloring with colors from the random lists tends to 1 as .Copyright © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 44, 317‐327, 2014 相似文献
152.
In the paper we prove two inequalities involving Gelfand numbers of operators with values in a Hilbert space. The first inequality is a Rademacher version of the main result in [Pa-To-1] which relates the Gelfand numbers of an operator from a Banach spaceX intol
2
n
with a certain Rademacher average for the dual operator. The second inequality states that the Gelfand numbers of an operatoru froml
1
N
into a Hilbert space satisfy the inequality
相似文献
153.
Carl C. Cowen 《Integral Equations and Operator Theory》1988,11(2):151-160
If ? is an analytic function mapping the unit diskD into itself, the composition operatorC ? is the operator onH 2 given byC ?f=fo?. The structure of the composition operatorC ? is usually complex, even if the function ? is fairly simple. In this paper, we consider composition operators whose symbol ? is a linear fractional transformation mapping the disk into itself. That is, we will assume throughout that $$\varphi \left( z \right) = \frac{{az + b}}{{cz + d}}$$ for some complex numbersa, b, c, d such that ? maps the unit diskD into itself. For this restricted class of examples, we address some of the basic questions of interest to operator theorists, including the computation of the adjoint. 相似文献
154.
In this paper we consider an initial boundary value problem for a reaction-diffusion equation under nonlinear and nonlocal Robin type boundary condition. Assuming the existence of an ordered pair of upper and lower solutions we establish a generalized quasilinearization method for the problem under consideration whose characteristic feature consists in the construction of monotone sequences converging to the unique solution within the interval of upper and lower solutions, and whose convergence rate is quadratic. Thus this method provides an efficient iteration technique that produces not only improved approximations due to the monotonicity of its iterates, but yields also a measure of the convergence rate. 相似文献
155.
156.
Carl Boor 《Advances in Computational Mathematics》2006,24(1-4):143-153
A lemma of Micchelli's, concerning radial polynomials and weighted sums of point evaluations, is shown to hold for arbitrary
linear functionals, as is Schaback's more recent extension of this lemma and Schaback's result concerning interpolation by
radial polynomials. Schaback's interpolant is explored.
Happy 60th and beyond, Charlie!
Mathematics subject classifications (2000) 41A05, 41A6. 相似文献
157.
Mathematische Semesterberichte - We describe in the form of a dialogue a development of various reflections on the combinatorics of set partitions; among the topics we pursue are... 相似文献
158.
The composition operators on H2 whose symbols are hyperbolic automorphisms of the unit disk fixing ±1 comprise a one-parameter group and the analytic Toeplitz operators coming from covering maps of annuli centered at the origin whose radii are reciprocals also form a one-parameter group. Using the eigenvectors of the composition operators and of the adjoints of the Toeplitz operators, a direct unitary equivalence is found between the restrictions to zH2 of the group of Toeplitz operators and the group of adjoints of these composition operators. On the other hand, it is shown that there is not a unitary equivalence of the groups of Toeplitz operators and the adjoints of the composition operators on the whole of H2, but there is a similarity between them. 相似文献
159.
Carl Christian Kjelgaard Mikkelsen 《BIT Numerical Mathematics》2011,51(4):959-975
Let A∈ℝ
n×n
and let B∈ℝ
n×p
and consider the Lyapunov matrix equation AX+XA
T
+BB
T
=0. If A+A
T
<0, then the extended Krylov subspace method (EKSM) can be used to compute a sequence of low rank approximations of X. In this paper we show how to construct a symmetric negative definite matrix A and a column vector B, for which the EKSM generates a predetermined residual curve. 相似文献
160.
Carl Bracken Eimear Byrne Gary McGuire Gabriele Nebe 《Designs, Codes and Cryptography》2011,61(3):261-272
Establishing the CCZ-equivalence of a pair of APN functions is generally quite difficult. In some cases, when seeking to show
that a putative new infinite family of APN functions is CCZ inequivalent to an already known family, we rely on computer calculation
for small values of n. In this paper we present a method to prove the inequivalence of quadratic APN functions with the Gold functions. Our main
result is that a quadratic function is CCZ-equivalent to the APN Gold function x2r+1{x^{2^r+1}} if and only if it is EA-equivalent to that Gold function. As an application of this result, we prove that a trinomial family
of APN functions that exist on finite fields of order 2
n
where n ≡ 2 mod 4 are CCZ inequivalent to the Gold functions. The proof relies on some knowledge of the automorphism group of a code
associated with such a function. 相似文献
|