全文获取类型
| 收费全文 | 2181篇 |
| 免费 | 83篇 |
| 国内免费 | 150篇 |
专业分类
| 化学 | 61篇 |
| 晶体学 | 12篇 |
| 力学 | 80篇 |
| 综合类 | 45篇 |
| 数学 | 2106篇 |
| 物理学 | 110篇 |
出版年
| 2025年 | 1篇 |
| 2024年 | 9篇 |
| 2023年 | 24篇 |
| 2022年 | 34篇 |
| 2021年 | 28篇 |
| 2020年 | 46篇 |
| 2019年 | 58篇 |
| 2018年 | 57篇 |
| 2017年 | 57篇 |
| 2016年 | 45篇 |
| 2015年 | 39篇 |
| 2014年 | 63篇 |
| 2013年 | 193篇 |
| 2012年 | 86篇 |
| 2011年 | 68篇 |
| 2010年 | 82篇 |
| 2009年 | 97篇 |
| 2008年 | 139篇 |
| 2007年 | 118篇 |
| 2006年 | 132篇 |
| 2005年 | 97篇 |
| 2004年 | 103篇 |
| 2003年 | 108篇 |
| 2002年 | 112篇 |
| 2001年 | 82篇 |
| 2000年 | 105篇 |
| 1999年 | 79篇 |
| 1998年 | 77篇 |
| 1997年 | 60篇 |
| 1996年 | 54篇 |
| 1995年 | 17篇 |
| 1994年 | 21篇 |
| 1993年 | 17篇 |
| 1992年 | 10篇 |
| 1991年 | 10篇 |
| 1990年 | 6篇 |
| 1989年 | 17篇 |
| 1988年 | 4篇 |
| 1987年 | 7篇 |
| 1986年 | 7篇 |
| 1985年 | 11篇 |
| 1984年 | 6篇 |
| 1983年 | 2篇 |
| 1982年 | 6篇 |
| 1981年 | 5篇 |
| 1980年 | 5篇 |
| 1979年 | 4篇 |
| 1978年 | 2篇 |
| 1977年 | 2篇 |
| 1975年 | 2篇 |
排序方式： 共有2414条查询结果，搜索用时 0 毫秒
41.
42.
O?uzhan Demirel Emine Soytürk Seyrantepe 《Journal of Mathematical Analysis and Applications》2011,374(2):566-572
In this paper we present a new characterization of Möbius transformations by use of hyperbolic regular polygons. 相似文献
43.
本讨论了多部有向图最大特征值的上界,并且给出了达到上界的充分且必要条件,从而推广了「２」,「３」和「４」的结论。 相似文献
44.
Serre's nonnegativity conjecture for intersection multiplicities has recently been proven by O. Gabber. In this paper we investigate Serre's positivity conjecture using the methods which he developed. We show in particular that the positivity conjecture has implications for properties of symbolic powers of prime ideals in regular local rings. 相似文献
45.
In this note, we characterize the regular probability measures satisfying the Choquet-Deny convolution equation =* on Abelian topological semigroups for a given probability measure . 相似文献
46.
Applying simulated annealing to location-planning models 总被引：9，自引：0，他引：9
Simulated annealing is a computational approach that simulates an annealing schedule used in producing glass and metals. Originally developed by Metropolis et al. in 1953, it has since been applied to a number of integer programming problems, including the p-median location-allocation problem. However, previously reported results by Golden and Skiscim in 1986 were less than encouraging. This article addresses the design of a simulated-annealing approach for the p-median and maximal covering location problems. This design has produced very good solutions in modest amounts of computer time. Comparisons with an interchange heuristic demonstrate that simulated annealing has potential as a solution technique for solving location-planning problems and further research should be encouraged. 相似文献
47.
48.
Jonn Angel L. Aranas Mark L. Loyola 《Acta Crystallographica. Section A, Foundations and Advances》2020,76(3):358-368
A geometric realization of an abstract polyhedron is a mapping that sends an i‐face to an open set of dimension i. This work adapts a method based on Wythoff construction to generate a full rank realization of an abstract regular polyhedron from its automorphism group Γ. The method entails finding a real orthogonal representation of Γ of degree 3 and applying its image to suitably chosen (not necessarily connected) open sets in space. To demonstrate the use of the method, it is applied to the abstract polyhedra whose automorphism groups are isomorphic to the non‐crystallographic Coxeter group H3. 相似文献
49.
Multiple zigzag chains of length n and width m constitute an important class of regular graphene flakes of rectangular shape. The physical and chemical properties of these basic pericondensed benzenoids can be related to their various topological invariants, conveniently encoded as the coefficients of a combinatorial polynomial, usually referred to as the ZZ polynomial of multiple zigzag chains . The current study reports a novel method for determination of these ZZ polynomials based on a hypothesized extension to John–Sachs theorem, used previously to enumerate Kekulé structures of various benzenoid hydrocarbons. We show that the ZZ polynomial of the multiple zigzag chain can be conveniently expressed as a determinant of a Toeplitz (or almost Toeplitz) matrix of size consisting of simple hypergeometric polynomials. The presented analysis can be extended to generalized multiple zigzag chains , i.e., derivatives of with a single attached polyacene chain of length k. All presented formulas are accompanied by formal proofs. The developed theoretical machinery is applied for predicting aromaticity distribution patterns in large and infinite multiple zigzag chains and for computing the distribution of spin densities in biradical states of finite multiple zigzag chains . 相似文献
50.
粗糙表面分维计算的立方体覆盖法 总被引：16，自引：0，他引：16
针对三角形棱柱表面积法和投影覆盖法在计算粗糙表面分形维数中存在的问题,提出了计算粗糙表面分维的立方体覆盖法,对计算结果进行了对比分析,并进一步对表面分维计算中的有关理论问题进行了分析,发现立方体覆盖法作为一种几何意义上的覆盖法,并计算结果比三角形棱柱表面积法和投影覆盖法更接近实际。 相似文献