全文获取类型
收费全文 | 578篇 |
免费 | 40篇 |
国内免费 | 21篇 |
专业分类
化学 | 43篇 |
力学 | 9篇 |
综合类 | 10篇 |
数学 | 555篇 |
物理学 | 22篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 15篇 |
2021年 | 5篇 |
2020年 | 20篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 7篇 |
2014年 | 20篇 |
2013年 | 36篇 |
2012年 | 18篇 |
2011年 | 30篇 |
2010年 | 25篇 |
2009年 | 36篇 |
2008年 | 43篇 |
2007年 | 32篇 |
2006年 | 49篇 |
2005年 | 22篇 |
2004年 | 21篇 |
2003年 | 17篇 |
2002年 | 19篇 |
2001年 | 27篇 |
2000年 | 19篇 |
1999年 | 28篇 |
1998年 | 26篇 |
1997年 | 13篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有639条查询结果,搜索用时 15 毫秒
91.
Spencer P. Hurd 《Discrete Mathematics》2008,308(13):2663-2673
We give some constructions of new infinite families of group divisible designs, GDD(n,2,4;λ1,λ2), including one which uses the existence of Bhaskar Rao designs. We show the necessary conditions are sufficient for 3?n?8. For n=10 there is one missing critical design. If λ1>λ2, then the necessary conditions are sufficient for . For each of n=10,15,16,17,18,19, and 20 we indicate a small minimal set of critical designs which, if they exist, would allow construction of all possible designs for that n. The indices of each of these designs are also among those critical indices for every n in the same congruence class mod 12. 相似文献
92.
We introduce the class of weak amicable T‐matrices and use it to construct a class of orthogonal designs, for p = 1 and for p a prime power ≡ 3 (mod 4), and all odd q, q ≤ 21. This class includes new Plotkin arrays of order 24, 40, 56 and for the first time, of orders 8q, q ∈ {9,11,13,15,17,19,21}. © 2006 Wiley Periodicals, Inc. J Combin Designs 16: 44–52, 2008 相似文献
93.
Latin hypercube designs have been found very useful for designing computer experiments. In recent years, several methods of constructing orthogonal Latin hypercube designs have been proposed in the literature. In this article, we report some more results on the construction of orthogonal Latin hypercubes which result in several new designs. 相似文献
94.
We introduce the notion of a partial geometric difference family as a variation on the classical difference family and a generalization of partial geometric difference sets. We study the relationship between partial geometric difference families and both partial geometric designs and difference families, and show that partial geometric difference families give rise to partial geometric designs. We construct several infinite families of partial geometric difference families using Galois rings and the cyclotomy of Galois fields. From these partial geometric difference families, we generate a list of infinite families of partial geometric designs and directed strongly regular graphs. 相似文献
95.
96.
Rajendra M. Pawale 《组合设计杂志》2007,15(1):49-60
The following results for proper quasi‐symmetric designs with non‐zero intersection numbers x,y and λ > 1 are proved.
- (1) Let D be a quasi‐symmetric design with z = y ? x and v ≥ 2k. If x ≥ 1 + z + z3 then λ < x + 1 + z + z3.
- (2) Let D be a quasi‐symmetric design with intersection numbers x, y and y ? x = 1. Then D is a design with parameters v = (1 + m) (2 + m)/2, b = (2 + m) (3 + m)/2, r = m + 3, k = m + 1, λ = 2, x = 1, y = 2 and m = 2,3,… or complement of one of these design or D is a design with parameters v = 5, b = 10, r = 6, k = 3, λ = 3, and x = 1, y = 2.
- (3) Let D be a triangle free quasi‐symmetric design with z = y ? x and v ≥ 2k, then x ≤ z + z2.
- (4) For fixed z ≥ 1 there exist finitely many triangle free quasi‐symmetric designs non‐zero intersection numbers x, y = x + z.
- (5) There do not exist triangle free quasi‐symmetric designs with non‐zero intersection numbers x, y = x + 2.
97.
It is shown that each critical set in a Latin square of order n > 6 has to have at least empty cells. © 2006 Wiley Periodicals, Inc. J Combin Designs 15: 77–83, 2007 相似文献
98.
99.
H. Kharaghani 《组合设计杂志》2000,8(3):166-173
A set of square real matrices is said to be amicable if for some permutation σ of the set . An infinite number of arrays which are suitable for any amicable set of eight circulant matrices are introduced. Applications include new classes of orthogonal designs. © 2000 John Wiley & Sons, Inc. J Combin Designs 8: 166–173, 2000 相似文献
100.
It is shown that for each integer m ≥ 1 there exists a lower bound, vm, with the property that for all v ≥ vm with v ≡ 1, 4 (mod 12) there exists an m-chromatic S(2, 4, v) design. © 1998 John Wiley & Sons, Inc. J Combin Designs 6: 403–409, 1998 相似文献