全文获取类型
收费全文 | 951篇 |
免费 | 51篇 |
国内免费 | 81篇 |
专业分类
化学 | 11篇 |
力学 | 11篇 |
综合类 | 4篇 |
数学 | 1008篇 |
物理学 | 49篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 20篇 |
2021年 | 16篇 |
2020年 | 27篇 |
2019年 | 33篇 |
2018年 | 28篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 31篇 |
2013年 | 100篇 |
2012年 | 50篇 |
2011年 | 55篇 |
2010年 | 50篇 |
2009年 | 61篇 |
2008年 | 69篇 |
2007年 | 47篇 |
2006年 | 56篇 |
2005年 | 50篇 |
2004年 | 31篇 |
2003年 | 42篇 |
2002年 | 44篇 |
2001年 | 31篇 |
2000年 | 24篇 |
1999年 | 28篇 |
1998年 | 23篇 |
1997年 | 27篇 |
1996年 | 18篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有1083条查询结果,搜索用时 421 毫秒
101.
B. R. Frieden 《Optics Communications》1998,150(1-6):15-21
We show how, in principle, to solve the ‘blind deconvolution' problem. This is in the context of the problem of imaging through atmospheric turbulence. The approach is digital but not iterative, and requires as input data but two short-exposure intensity images, without the need for reference point sources. By taking the Fourier transform of each image and dividing, a set of linear equations is generated whose unknowns are sampled values of the two random point spread functions that degraded the images. An oversampling by 50% in Fourier space equalizes the number of unknowns and independent equations. With some prior knowledge of spread function support, and in the absence of added noise of image detection, the inverted equations give exact solutions. The two observed images are then inverse filtered to reconstruct the object. 相似文献
102.
In this paper, a family of the skew elliptical distributions is defined and investigated. Some basic properties, such as stochastic representation, marginal and conditional distributions, distribution under linear transformations, moments and moment generating function are derived. The joint distribution of several quadratic forms is obtained. An example is given to show that the distributions of some statistics as the functions of the quadratic forms can be derived for various applications. 相似文献
103.
We give an inequality for the group chromatic number of a graph as an extension of Brooks’ Theorem. Moreover, we obtain a structural theorem for graphs satisfying the equality and discuss applications of the theorem. 相似文献
104.
105.
The notion of a split coloring of a complete graph was introduced by Erd?s and Gyárfás [ 7 ] as a generalization of split graphs. In this work, we offer an alternate interpretation by comparing such a coloring to the classical Ramsey coloring problem via a two‐round game played against an adversary. We show that the techniques used and bounds obtained on the extremal (r,m)‐split coloring problem of [ 7 ] are closer in nature to the Turán theory of graphs rather than Ramsey theory. We extend the notion of these colorings to hypergraphs and provide bounds and some exact results. © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 226–237, 2002 相似文献
106.
Charles E. Blair 《Mathematical Programming》1978,15(1):87-91
The duality theorem of linear programming is used to prove several results on convex optimization. This is done without using separating hyerplane theorems.This work was supported in part by a grant from Investors in Business Education. 相似文献
107.
A color pattern is a graph whose edges have been partitioned into color classes. A family of color patterns is a Ramsey family provided there is some sufficiently large integer N such that in any edge coloring of the complete graph KN there is an (isomorphic) copy of at least one of the patterns from . The smallest such N is the Ramsey number of the family . The classical Canonical Ramsey theorem of Erds and Rado asserts that the family of color patterns is a Ramsey family if it consists of monochromatic, rainbow (totally multicolored) and lexically colored complete graphs. In this paper we treat the asymmetric case by studying the Ramsey number of families containing a rainbow triangle, a lexically colored complete graph and a fixed arbitrary monochromatic graph. In particular we give asymptotically tight bounds for the Ramsey number of a family consisting of rainbow and monochromatic triangle and a lexically colored KN. Among others, we prove some canonical Ramsey results for cycles. 相似文献
108.
Jesus Ferrer 《Czechoslovak Mathematical Journal》2005,55(2):499-501
We give an example of a fourth degree polynomial which does not satisfy Rolles Theorem in the unit ball of l
2.The author has been partially supported by MCyT and FEDER Project BFM2002-01423. 相似文献
109.
Summary Let <InlineEquation ID=IE"1"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"2"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"3"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"4"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"5"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"6"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"7"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"8"><EquationSource Format="TEX"><![CDATA[<InlineEquation
ID=IE"9"><EquationSource Format="TEX"><![CDATA[$]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>{\cal
{X}}_{n} =(X_1,\ldots,X_n)$ be a random vector. Suppose that the random variables $(X_i)_{1\leq i\leq n}$ are stationary and
fulfill a suitable dependence criterion. Let $f$ be a real valued function defined on $\mathbbm{R}^n$ having some regular
properties. Let ${\cal {Y}}_{n}$ be a random vector, independent of ${\cal {X}}_{n}$, having independent and identically distributed
components. We control $\left|\mathbbm{E}(f({\cal {X}}_{n}))-\mathbbm{E} (f({\cal {Y}}_{n}))\right|$. Suitable choices of
the function $f$ yield, under minimal conditions, to rates of convergence in the central limit theorem, to some moment inequalities
or to bounds useful for Poisson approximation. The proofs are derived from multivariate extensions of Taylor's formula and
of the Lindeberg decomposition. In the univariate case and in the mixing setting the method is due to Rio (1995). 相似文献
110.
Fu-Chuen Chang 《Annals of the Institute of Statistical Mathematics》2005,57(4):833-844
This paper is concerned with the problem of computing approximateD-optimal design for polynomial regression with analytic weight function on a interval [m
0-a,m
0+a]. It is shown that the structure of the optimal design depends ona and weight function. Moreover, the optimal support points and weights are analytic functions ofa ata=0. We make use of a Taylor expansion to provide a recursive procedure for calculating theD-optimal designs. 相似文献