全文获取类型
收费全文 | 6985篇 |
免费 | 85篇 |
国内免费 | 29篇 |
专业分类
化学 | 137篇 |
力学 | 40篇 |
综合类 | 2篇 |
数学 | 6691篇 |
物理学 | 229篇 |
出版年
2023年 | 17篇 |
2022年 | 19篇 |
2021年 | 13篇 |
2020年 | 28篇 |
2019年 | 76篇 |
2018年 | 85篇 |
2017年 | 41篇 |
2016年 | 41篇 |
2015年 | 38篇 |
2014年 | 104篇 |
2013年 | 334篇 |
2012年 | 170篇 |
2011年 | 354篇 |
2010年 | 389篇 |
2009年 | 506篇 |
2008年 | 505篇 |
2007年 | 447篇 |
2006年 | 235篇 |
2005年 | 169篇 |
2004年 | 99篇 |
2003年 | 120篇 |
2002年 | 140篇 |
2001年 | 160篇 |
2000年 | 179篇 |
1999年 | 191篇 |
1998年 | 230篇 |
1997年 | 202篇 |
1996年 | 137篇 |
1995年 | 136篇 |
1994年 | 159篇 |
1993年 | 148篇 |
1992年 | 171篇 |
1991年 | 153篇 |
1990年 | 159篇 |
1989年 | 167篇 |
1988年 | 110篇 |
1987年 | 96篇 |
1986年 | 120篇 |
1985年 | 94篇 |
1984年 | 113篇 |
1983年 | 41篇 |
1982年 | 90篇 |
1981年 | 53篇 |
1980年 | 89篇 |
1979年 | 62篇 |
1978年 | 68篇 |
1977年 | 24篇 |
1976年 | 7篇 |
1973年 | 3篇 |
1971年 | 2篇 |
排序方式: 共有7099条查询结果,搜索用时 187 毫秒
11.
Wu Hongyi 《高校应用数学学报(英文版)》2006,21(1):96-106
A family of Said-Bézier type generalized Ball (SBGB) bases and surfaces with a parameter H over triangular domain is introduced, which unifies Bézier surface and Said-Ball surface and includes several intermediate
surfaces. To convert different bases and surfaces, the dual functionals of bases are presented. As an application of dual
functionals, the subdivision formulas for surfaces are established. 相似文献
12.
Summary In this paper a Gauss-Jordan algorithm with column interchanges is presented and analysed. We show that, in contrast with Gaussian elimination, the Gauss-Jordan algorithm has essentially differing properties when using column interchanges instead of row interchanges for improving the numerical stability. For solutions obtained by Gauss-Jordan with column interchanges, a more satisfactory bound for the residual norm can be given. The analysis gives theoretical evidence that the algorithm yields numerical solutions as good as those obtained by Gaussian elimination and that, in most practical situations, the residuals are equally small. This is confirmed by numerical experiments. Moreover, timing experiments on a Cyber 205 vector computer show that the algorithm presented has good vectorisation properties. 相似文献
13.
Sauer, Shelah, Vapnik and Chervonenkis proved that if a set system on n vertices contains many sets, then the set system has full trace on a large set. Although the restriction on the size of the
groundset cannot be lifted, Frankl and Pach found a trace structure that is guaranteed to occur in uniform set systems even
if we do not bound the size of the groundset. In this note we shall give three sequences of structures such that every set
system consisting of sufficiently many sets contains at least one of these structures with many sets. 相似文献
14.
Admissible slopes for monotone and convex interpolation 总被引:1,自引:0,他引:1
Summary In many applications, interpolation of experimental data exhibiting some geometric property such as nonnegativity, monotonicity or convexity is unacceptable unless the interpolant reflects these characteristics. This paper identifies admissible slopes at data points of variousC
1 interpolants which ensure a desirable shape. We discuss this question, in turn for the following function classes commonly used for shape preserving interpolations: monotone polynomials,C
1 monotone piecewise polynomials, convex polynomials, parametric cubic curves and rational functions. 相似文献
15.
Victor Bondarenko 《Bulletin des Sciences Mathématiques》2003,127(3):191-206
In present paper the parabolic equation solution is built. The construction is reduced to iterative procedure. And convergence of the latter is proven. 相似文献
16.
Modifying complex plane rotations, we derive a new Jacobi-type algorithm for the Hermitian eigendecomposition, which uses only real arithmetic. When the fast-scaled rotations are incorporated, the new algorithm brings a substantial reduction in computational costs. The new method has the same convergence properties and parallelism as the symmetric Jacobi algorithm. Computational test results show that it produces accurate eigenvalues and eigenvectors and achieves great reduction in computational time.The work of this author was supported in part by the National Science Foundation grant CCR-8813493 and by the University of Minnesota Army High Performance Computing Research Center contract DAAL 03-89-C-0038.The work of this author was supported in part by the University of Minnesota Army High Performance Computing Research Center contract DAAL 03-89-C-0038. 相似文献
17.
J. Schropp 《Numerische Mathematik》1997,78(1):87-101
Summary. We use the qualitative properties of the solution flow of the gradient equation to compute a local minimum of a real-valued function . Under the regularity assumption of all equilibria we show a convergence result for bounded trajectories of a consistent,
strictly stable linear multistep method applied to the gradient equation. Moreover, we compare the asymptotic features of
the numerical and the exact solutions as done by Humphries, Stuart (1994) and Schropp (1995) for one-step methods. In the
case of -stable formulae this leads to an efficient solver for stiff minimization problems.
Received July 10, 1995 / Revised version received June 27, 1996 相似文献
18.
A. Sánchez-Lavega A. Salazar A. Ocariz L. Pottier E. Gomez L.M. Villar E. Macho 《Applied Physics A: Materials Science & Processing》1997,65(1):15-22
Received: 16 September 1996/Accepted: 6 January 1997 相似文献
19.
Regularity of multiwavelets 总被引:7,自引:0,他引:7
The motivation for this paper is an interesting observation made by Plonka concerning the factorization of the matrix symbol associated with the refinement equation for B-splines with equally spaced multiple knots at integers and subsequent developments which relate this factorization to regularity of refinable vector fields over the real line. Our intention is to contribute to this train of ideas which is partially driven by the importance of refinable vector fields in the construction of multiwavelets. The use of subdivision methods will allow us to consider the problem almost entirely in the spatial domain and leads to exact characterizations of differentiability and Hölder regularity in arbitrary L p spaces. We first study the close relationship between vector subdivision schemes and a generalized notion of scalar subdivision schemes based on bi-infinite matrices with certain periodicity properties. For the latter type of subdivision scheme we will derive criteria for convergence and Hölder regularity of the limit function, which mainly depend on the spectral radius of a bi-infinite matrix induced by the subdivision operator, and we will show that differentiability of the limit functions can be characterized by factorization properties of the subdivision operator. By switching back to vector subdivision we will transfer these results to refinable vectors fields and obtain characterizations of regularity by factorization and spectral radius properties of the symbol associated to the refinable vector field. Finally, we point out how multiwavelets can be generated from orthonormal refinable bi-infinite vector fields. 相似文献
20.
Kevin Houston 《Inventiones Mathematicae》2002,147(3):471-485
The disentanglement of certain augmentations is shown to be the topological join of a disentanglement and a Milnor fibre.
The kth disentanglement of a finite map is defined and for corank 1 maps from ℂ
n
to ℂ
n
+1 it is shown that they are homotopically equivalent to a wedge of spheres. Applications to the Mond conjecture are given.
Oblatum 24-VII-2000 & 5-VII-2001?Published online: 12 October 2001 相似文献