全文获取类型
收费全文 | 12751篇 |
免费 | 795篇 |
国内免费 | 925篇 |
专业分类
化学 | 764篇 |
晶体学 | 7篇 |
力学 | 581篇 |
综合类 | 79篇 |
数学 | 8068篇 |
物理学 | 1608篇 |
综合类 | 3364篇 |
出版年
2023年 | 100篇 |
2022年 | 98篇 |
2021年 | 138篇 |
2020年 | 212篇 |
2019年 | 237篇 |
2018年 | 262篇 |
2017年 | 306篇 |
2016年 | 331篇 |
2015年 | 273篇 |
2014年 | 545篇 |
2013年 | 826篇 |
2012年 | 635篇 |
2011年 | 648篇 |
2010年 | 570篇 |
2009年 | 795篇 |
2008年 | 909篇 |
2007年 | 857篇 |
2006年 | 783篇 |
2005年 | 676篇 |
2004年 | 539篇 |
2003年 | 547篇 |
2002年 | 512篇 |
2001年 | 377篇 |
2000年 | 386篇 |
1999年 | 389篇 |
1998年 | 320篇 |
1997年 | 340篇 |
1996年 | 216篇 |
1995年 | 210篇 |
1994年 | 185篇 |
1993年 | 144篇 |
1992年 | 122篇 |
1991年 | 107篇 |
1990年 | 110篇 |
1989年 | 106篇 |
1988年 | 87篇 |
1987年 | 67篇 |
1986年 | 54篇 |
1985年 | 59篇 |
1984年 | 61篇 |
1983年 | 19篇 |
1982年 | 42篇 |
1981年 | 35篇 |
1980年 | 34篇 |
1979年 | 30篇 |
1978年 | 31篇 |
1977年 | 38篇 |
1976年 | 25篇 |
1974年 | 17篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
11.
12.
In this paper, the authors studied certain properties of the estimate of Liang and Krishnaiah (1985, J. Multivariate Anal. 16, 162–172) for multivariate binary density. An alternative shrinkage estimate is also obtained. The above results are generalized to general orthonormal systems. 相似文献
13.
Yoel Shkolnisky Mark Tygert Vladimir Rokhlin 《Applied and Computational Harmonic Analysis》2006,21(3):413-420
Many signals encountered in science and engineering are approximated well by bandlimited functions. We provide suitable error bounds for the approximation of bandlimited functions by linear combinations of certain special functions—the prolate spheroidal wave functions of order 0. The coefficients in the approximating linear combinations are given explicitly via appropriate quadrature formulae. 相似文献
14.
Well-Posedness by Perturbations of Variational Problems 总被引:3,自引:0,他引:3
Lemaire B. Ould Ahmed Salem C. Revalski J. P. 《Journal of Optimization Theory and Applications》2002,115(2):345-368
In this paper, we consider the extension of the notion of well-posedness by perturbations, introduced by Zolezzi for optimization problems, to other related variational problems like inclusion problems and fixed-point problems. Then, we study the conditions under which there is equivalence of the well-posedness in the above sense between different problems. Relations with the so-called diagonal well-posedness are also given. Finally, an application to staircase iteration methods is presented. 相似文献
15.
G. Dattoli 《Journal of Mathematical Analysis and Applications》2002,269(2):716-725
Bilateral generating functions are those involving products of different types of polynomials. We show that operational methods offer a powerful tool to derive these families of generating functions. We study cases relevant to products of Hermite polynomials with Laguerre, Legendre and other polynomials. We also propose further extensions of the method which we develop here. 相似文献
16.
Filippo Bracci Roberto Tauraso Fabio Vlacci 《Journal of Mathematical Analysis and Applications》2002,270(2):1131-473
Let f,g be two commuting holomorphic self-maps of the unit disc. If f and g agree at the common Wolff point up to a certain order of derivatives (no more than 3 if the Wolff point is on the unit circle), then f≡g. 相似文献
17.
根据Pegg-Barnett位相定义, 计算了一种新的奇偶非线性相干态的位相概率分布函数, 利用数值计算方法研究了它们的位相统计性质. 数值计算结果表明:新的奇偶非线性相干态的位相特性与通常奇偶相干态的位相特性截然不同. 相似文献
18.
Lorenz混沌系统的输入—输出性质分析 总被引:1,自引:0,他引:1
研究了Lorenz混沌系统的一类输入—输出性质,采用Lyapunov直接方法和数值仿真等研究方法,对Lorenz混沌系统的解的范数分别与输入信号的振幅、角频率之间的关系进行了分析,得出了诸多有意义而在线性系统中没有的结论,这对进一步研究Lorenz系统有重要的参考意义。 相似文献
19.
设函数f(w)为凸区域D内的单叶解析函数,对于2≤n≤8和所有w∈D,本文得到估计式|f(n)(w)/f'(w)|的精确上界.这个结果推广了一些已知的结论. 相似文献
20.
Efficient measurement of the performance index (the distance of a loading parameter from the voltage collapse point) is one of the key problems in power system operations and planning and such an index indicates the severity of a power system with regard to voltage collapse. There exist many interesting methods and ideas to compute this index. However, some successful methods are not yet mathematically justified while other mathematically sound methods are often proposed directly based on the bifurcation theory and they require the initial stationary state to be too close to the unknown turning point to make the underlying methods practical.This paper first gives a survey of several popular methods for estimating the fold bifurcation point including the continuation methods, bifurcation methods and the test function methods (Seydel's direct solution methods, the tangent vector methods and the reduced Jacobian method) and discuss their relative advantages and problems. Test functions are usually based on scaling of the determinant of the Jacobian matrix and it is generally not clear how to determine the behaviour of such functions. As the underlying nonlinear equations are of a particular type, this allows us to do a new analysis of the determinants of the Jacobian and its submatrices in this paper. Following the analysis, we demonstrate how to construct a class of test functions with a predictable analytical behaviour so that a suitable index can be produced. Finally, examples of two test functions from this class are proposed. For several standard IEEE test systems, promising numerical results have been achieved. 相似文献