全文获取类型
收费全文 | 3508篇 |
免费 | 206篇 |
国内免费 | 155篇 |
专业分类
化学 | 124篇 |
晶体学 | 3篇 |
力学 | 73篇 |
综合类 | 34篇 |
数学 | 3221篇 |
物理学 | 414篇 |
出版年
2024年 | 6篇 |
2023年 | 61篇 |
2022年 | 78篇 |
2021年 | 62篇 |
2020年 | 122篇 |
2019年 | 115篇 |
2018年 | 119篇 |
2017年 | 111篇 |
2016年 | 81篇 |
2015年 | 87篇 |
2014年 | 136篇 |
2013年 | 308篇 |
2012年 | 120篇 |
2011年 | 191篇 |
2010年 | 187篇 |
2009年 | 331篇 |
2008年 | 269篇 |
2007年 | 217篇 |
2006年 | 196篇 |
2005年 | 133篇 |
2004年 | 123篇 |
2003年 | 116篇 |
2002年 | 107篇 |
2001年 | 88篇 |
2000年 | 83篇 |
1999年 | 71篇 |
1998年 | 71篇 |
1997年 | 60篇 |
1996年 | 38篇 |
1995年 | 19篇 |
1994年 | 20篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 14篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1970年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有3869条查询结果,搜索用时 62 毫秒
1.
《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2021,38(5):1337-1371
In this paper we consider minimizers of the functional where is a bounded open set and where are the first k eigenvalues on Ω of an operator in divergence form with Dirichlet boundary condition and with Hölder continuous coefficients. We prove that the optimal sets have finite perimeter and that their free boundary is composed of a regular part, which is locally the graph of a -regular function, and a singular part, which is empty if , discrete if and of Hausdorff dimension at most if , for some . 相似文献
2.
3.
For an integer , a graph is -hamiltonian if for any vertex subset with , is hamiltonian, and is -hamiltonian connected if for any vertex subset with , is hamiltonian connected. Thomassen in 1984 conjectured that every 4-connected line graph is hamiltonian (see Thomassen, 1986), and Ku?zel and Xiong in 2004 conjectured that every 4-connected line graph is hamiltonian connected (see Ryjá?ek and Vrána, 2011). In Broersma and Veldman (1987), Broersma and Veldman raised the characterization problem of -hamiltonian line graphs. In Lai and Shao (2013), it is conjectured that for , a line graph is -hamiltonian if and only if is -connected. In this paper we prove the following.(i) For an integer , the line graph of a claw-free graph is -hamiltonian if and only if is -connected.(ii) The line graph of a claw-free graph is 1-hamiltonian connected if and only if is 4-connected. 相似文献
4.
5.
6.
Given an ‐vertex pseudorandom graph and an ‐vertex graph with maximum degree at most two, we wish to find a copy of in , that is, an embedding so that for all . Particular instances of this problem include finding a triangle‐factor and finding a Hamilton cycle in . Here, we provide a deterministic polynomial time algorithm that finds a given in any suitably pseudorandom graph . The pseudorandom graphs we consider are ‐bijumbled graphs of minimum degree which is a constant proportion of the average degree, that is, . A ‐bijumbled graph is characterised through the discrepancy property: for any two sets of vertices and . Our condition on bijumbledness is within a log factor from being tight and provides a positive answer to a recent question of Nenadov. We combine novel variants of the absorption‐reservoir method, a powerful tool from extremal graph theory and random graphs. Our approach builds on our previous work, incorporating the work of Nenadov, together with additional ideas and simplifications. 相似文献
7.
8.
9.
Martín D. Safe 《Journal of Graph Theory》2020,93(2):268-298
A graph is concave-round if its vertices can be circularly enumerated so that the closed neighborhood of each vertex is an interval in the enumeration. In this study, we give a minimal forbidden induced subgraph characterization for the class of concave-round graphs, solving a problem posed by Bang-Jensen, Huang, and Yeo [SIAM J. Discrete Math., 13 (2000), pp. 179–193]. In addition, we show that it is possible to find one such forbidden induced subgraph in linear time in any given graph that is not concave-round. As part of the analysis, we obtain characterizations by minimal forbidden submatrices for the circular-ones property for rows and for the circular-ones property for rows and columns and show that, also for both variants of the property, one of the corresponding forbidden submatrices can be found (if present) in any given matrix in linear time. We make some final remarks regarding connections to some classes of circular-arc graphs. 相似文献
10.
Tanja Vidaković-Koch Tamara Miličić Luka A. Živković Hoon Seng Chan Ulrike Krewer Menka Petkovska 《Current Opinion in Electrochemistry》2021
The nonlinear frequency response analysis (NFRA) can be seen as an extension of electrochemical impedance spectroscopy. NFRA gives a full and detailed representation of the system response and can establish a connection between model parameters and the experimentally observed phenomena. In this article, different theoretical NFRA approaches and the most recent application examples are discussed. A simple electrochemical example is used to showcase the benefits and disadvantages of analyzing the system response by using different approaches. In addition, it was shown how to extract experimental harmonic values and analyze them. 相似文献