全文获取类型
收费全文 | 2308篇 |
免费 | 193篇 |
国内免费 | 127篇 |
专业分类
化学 | 279篇 |
晶体学 | 9篇 |
力学 | 113篇 |
综合类 | 58篇 |
数学 | 1498篇 |
物理学 | 671篇 |
出版年
2024年 | 5篇 |
2023年 | 33篇 |
2022年 | 53篇 |
2021年 | 49篇 |
2020年 | 63篇 |
2019年 | 59篇 |
2018年 | 63篇 |
2017年 | 92篇 |
2016年 | 99篇 |
2015年 | 63篇 |
2014年 | 158篇 |
2013年 | 179篇 |
2012年 | 102篇 |
2011年 | 109篇 |
2010年 | 114篇 |
2009年 | 156篇 |
2008年 | 151篇 |
2007年 | 153篇 |
2006年 | 118篇 |
2005年 | 106篇 |
2004年 | 80篇 |
2003年 | 82篇 |
2002年 | 77篇 |
2001年 | 69篇 |
2000年 | 73篇 |
1999年 | 61篇 |
1998年 | 54篇 |
1997年 | 36篇 |
1996年 | 24篇 |
1995年 | 14篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 6篇 |
1991年 | 15篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有2628条查询结果,搜索用时 15 毫秒
41.
Alexandre N. Carvalho José A. Langa James C. Robinson 《Journal of Differential Equations》2010,249(12):3099-3109
We provide bounds on the upper box-counting dimension of negatively invariant subsets of Banach spaces, a problem that is easily reduced to covering the image of the unit ball under a linear map by a collection of balls of smaller radius. As an application of the abstract theory we show that the global attractors of a very broad class of parabolic partial differential equations (semilinear equations in Banach spaces) are finite-dimensional. 相似文献
42.
The main aim of this paper is to establish an Ostrowski type inequality on H-type groups using the L∞ norm of the horizontal gradient. The work has been motivated by the work of Anastassiou and Goldstein in [G.A. Anastassiou, J.A. Goldstein, Higher order Ostrowski type inequalities over Euclidean domains, J. Math. Anal. Appl. 337 (2008) 962-968]. 相似文献
43.
Robert Hable 《International Journal of Approximate Reasoning》2010,51(9):1114-1128
The article considers estimating a parameter θ in an imprecise probability model which consists of coherent upper previsions . After the definition of a minimum distance estimator in this setup and a summarization of its main properties, the focus lies on applications. It is shown that approximate minimum distances on the discretized sample space can be calculated by linear programming. After a discussion of some computational aspects, the estimator is applied in a simulation study consisting of two different models. Finally, the estimator is applied on a real data set in a linear regression model. 相似文献
44.
Let G be a simple graph. We first show that ■, where δiand di denote the i-th signless Laplacian eigenvalue and the i-th degree of vertex in G, respectively.Suppose G is a simple and connected graph, then some inequalities on the distance signless Laplacian eigenvalues are obtained by deleting some vertices and some edges from G. In addition, for the distance signless Laplacian spectral radius ρQ(G), we determine the extremal graphs with the minimum ρQ(G) among the trees with given diameter, the unicyclic and bicyclic graphs with given girth, respectively. 相似文献
45.
J.M. Díaz-Báñez M. Korman P. Pérez-Lantero I. Ventura 《European Journal of Operational Research》2014
In this paper we study a facility location problem in the plane in which a single point (facility) and a rapid transit line (highway) are simultaneously located in order to minimize the total travel time from the clients to the facility, using the L1 or Manhattan metric. The rapid transit line is given by a segment with any length and orientation, and is an alternative transportation line that can be used by the clients to reduce their travel time to the facility. We study the variant of the problem in which clients can enter and exit the highway at any point. We provide an O(n3)-time algorithm that solves this variant, where n is the number of clients. We also present a detailed characterization of the solutions, which depends on the speed given along the highway. 相似文献
46.
We present an approximation method of circular arcs using linear-normal (LN) Bézier curves of even degree, four and higher. Our method achieves Gm continuity for endpoint interpolation of a circular arc by a LN Bézier curve of degree 2m , for m=2,3. We also present the exact Hausdorff distance between the circular arc and the approximating LN Bézier curve. We show that the LN curve has an approximation order of 2m+2, for m=2,3. Our approximation method can be applied to offset approximation, so obtaining a rational Bézier curve as an offset approximant. We derive an algorithm for offset approximation based on the LN circle approximation and illustrate our method with some numerical examples. 相似文献
47.
本文利用比较方法和Kuratowski非紧致测度研究Banach空间闭子集上微分方程解的整体存在唯一性,得出了一个一般性判别准则.作为特例,本文的结果包含了文[4]中的主要定理. 相似文献
48.
Erich Peter Klement 《Fuzzy Sets and Systems》1980,4(1):83-93
In this paper we first give an axiomatic definition of a fuzzy σ-algebra which is a generalisation of the family of fuzzy events considered by L.A. Zadeh [13]. The relationship between classical and fuzzy σ-algebras and between topologies and σ-algebras, in both cases, classical and fuzzy, is established in the notation of commutative diagrams. For fuzzy topologies we refer to the work of R. Lowen [8]. After a comparison between classical measurability of functions and fuzzy measurability defined in this paper we finally introduce the product of fuzzy σ-algebras. 相似文献
49.
A random graph Gn(x) is constructed on independent random points U1,…,Un distributed uniformly on [0,1]d, d1, in which two distinct such points are joined by an edge if the l∞-distance between them is at most some prescribed value 0<x<1. The connectivity distance cn, the smallest x for which Gn(x) is connected, is shown to satisfy For d2, the random graph Gn(x) behaves like a d-dimensional version of the random graphs of Erdös and Rényi, despite the fact that its edges are not independent: cn/dn→1, a.s., as n→∞, where dn is the largest nearest-neighbor link, the smallest x for which Gn(x) has no isolated vertices. 相似文献
50.
Necessary conditions for the Gâteaux differentiability of the distance function to a set are considered. A series of characterizing results is obtained. 相似文献