全文获取类型
收费全文 | 952篇 |
免费 | 44篇 |
国内免费 | 27篇 |
专业分类
化学 | 7篇 |
晶体学 | 3篇 |
力学 | 6篇 |
综合类 | 18篇 |
数学 | 815篇 |
物理学 | 174篇 |
出版年
2024年 | 1篇 |
2023年 | 33篇 |
2022年 | 38篇 |
2021年 | 49篇 |
2020年 | 46篇 |
2019年 | 26篇 |
2018年 | 19篇 |
2017年 | 24篇 |
2016年 | 32篇 |
2015年 | 18篇 |
2014年 | 35篇 |
2013年 | 39篇 |
2012年 | 14篇 |
2011年 | 32篇 |
2010年 | 22篇 |
2009年 | 62篇 |
2008年 | 75篇 |
2007年 | 54篇 |
2006年 | 61篇 |
2005年 | 26篇 |
2004年 | 29篇 |
2003年 | 36篇 |
2002年 | 52篇 |
2001年 | 41篇 |
2000年 | 31篇 |
1999年 | 51篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 15篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有1023条查询结果,搜索用时 31 毫秒
21.
22.
Zoltán Lóránt Nagy 《Journal of Graph Theory》2017,84(4):566-580
We study the existence and the number of k‐dominating independent sets in certain graph families. While the case namely the case of maximal independent sets—which is originated from Erd?s and Moser—is widely investigated, much less is known in general. In this paper we settle the question for trees and prove that the maximum number of k‐dominating independent sets in n‐vertex graphs is between and if , moreover the maximum number of 2‐dominating independent sets in n‐vertex graphs is between and . Graph constructions containing a large number of k‐dominating independent sets are coming from product graphs, complete bipartite graphs, and finite geometries. The product graph construction is associated with the number of certain Maximum Distance Separable (MDS) codes. 相似文献
23.
研究了二元叠加码Mq(t,k,d)也是一个二元等重码,给出了它成为最佳等重码的条件,研究了它的检错性. 相似文献
24.
The main results of this paper are in two directions. First, the family of finite local Frobenius non-chain rings of length 4 (hence of nilpotency index 3) is determined. As a by-product all finite local Frobenius non-chain rings with elements, (p a prime) are given. Second, the number and structure of γ-constacyclic codes over finite local Frobenius non-chain rings with nilpotency index 3, of length relatively prime to the characteristic of the residue field of the ring, are determined. 相似文献
25.
26.
27.
Finite commutative semi-simple rings are direct sum of finite fields. In this study, we investigate the algebraic structure of λ-constacyclic codes over such finite semi-simple rings. Among others, necessary and sufficient conditions for the existence of self-dual, LCD, and Hermitian dual-containing λ-constacyclic codes over finite semi-simple rings are provided. Using the CSS and Hermitian constructions, quantum MDS codes over finite semi-simple rings are constructed. 相似文献
28.
As a generalization of cyclic codes, constacyclic codes is an important and interesting class of codes due to their nice algebraic structures and various applications in engineering. This paper is devoted to the study of the q-polynomial approach to constacyclic codes. Fundamental theory of this approach will be developed, and will be employed to construct some families of optimal and almost optimal codes in this paper. 相似文献
29.
Cyclic codes are an important class of linear codes, whose weight distribution have been extensively studied. So far, most of previous results obtained were for cyclic codes with no more than three nonzeros. Recently, the authors of [37] constructed a class of cyclic codes with arbitrary number of nonzeros, and computed the weight distribution for several cases. In this paper, we determine the weight distribution for a new family of such codes. This is achieved by introducing certain new methods, such as the theory of Jacobi sums over finite fields and subtle treatment of some complicated combinatorial identities. 相似文献