全文获取类型
收费全文 | 325篇 |
免费 | 5篇 |
国内免费 | 22篇 |
专业分类
化学 | 60篇 |
力学 | 7篇 |
综合类 | 2篇 |
数学 | 252篇 |
物理学 | 31篇 |
出版年
2023年 | 23篇 |
2022年 | 16篇 |
2021年 | 5篇 |
2020年 | 13篇 |
2019年 | 7篇 |
2018年 | 13篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 19篇 |
2012年 | 10篇 |
2011年 | 29篇 |
2010年 | 26篇 |
2009年 | 41篇 |
2008年 | 21篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 13篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有352条查询结果,搜索用时 125 毫秒
221.
François Genest 《Discrete Mathematics》2009,309(11):3714-1089
The long standing Cycle Double Cover Conjecture states that every bridgeless graph can be covered by a family of cycles such that every edge is covered exactly twice. Intimately related is the problem of finding, in an eulerian graph, a circuit decomposition compatible with a given transition system (transition systems are also known as decompositions into closed paths). One approach that seems promising consists in finding a black anticlique in the corresponding Sabidussi orbit of bicolored circle graphs. 相似文献
222.
Siham Bekkai 《Discrete Applied Mathematics》2009,157(4):774-779
We show that a graph with minimum degree δ, independence number α≥δ and without isolated vertices, possesses a partition by vertex-disjoint cycles and at most α−δ+1 edges or vertices. 相似文献
223.
We consider the busy period in the GI/M/1 queue with multiple exponential vacations. We derive the transform of the joint distribution of the length of a busy period, the number of customers served during the busy period, and the residual interarrival time at the instant the busy period ends. 相似文献
224.
Wei-Fan Wang 《Discrete Mathematics》2006,306(2):262-270
Let G be a graph of nonnegative characteristic and let g(G) and Δ(G) be its girth and maximum degree, respectively. We show that G has an edge-partition into a forest and a subgraph H so that (1) Δ(H)?1 if g(G)?11; (2) Δ(H)?2 if g(G)?7; (3) Δ(H)?4 if either g(G)?5 or G does not contain 4-cycles and 5-cycles; (4) Δ(H)?6 if G does not contain 4-cycles. These results are applied to find the following upper bounds for the game coloring number colg(G) of G: (1) colg(G)?5 if g(G)?11; (2) colg(G)?6 if g(G)?7; (3) colg(G)?8 if either g(G)?5 or G contains no 4-cycles and 5-cycles; (4) colg(G)?10 if G does not contain 4-cycles. 相似文献
225.
Han Ren Mo Deng 《应用数学学报(英文版)》2008,24(4):677-680
In this paper we investigate cycle base structures of a (weighted) graph and show that much information of short cycles is contained in a MCB (minimum cycle base). After setting up a Hall type theorem for base-transformation, we give a sufficient and necessary condition for a cycle base to be a MCB. Further more, we show that the structure of MCB in a (weighted) graph is unique. In the case of nonnegative weight, every pair of MCB have the same number of k-cycles for each integer k ≥ 3. The property is also true for those having longest length (although much work has been down in evaluating MCB, little is known for those having longest length). 相似文献
226.
Cristian Grossmann Christian Langel Marco Mazzotti Manfred Morari Massimo Morbidelli 《Journal of chromatography. A》2010,1217(13):2013-2021
In order to better exploit the economic potential of the simulated moving bed chromatography a ‘cycle to cycle’ controller which only requires the information about the linear adsorption behavior and the overall average porosity of the columns has been proposed. Recently, an automated on-line HPLC monitoring system which determines the concentrations in the two product streams averaged over one cycle, and returns them as feedback information to the controller was implemented. The new system allows for an accurate determination of the average concentration of the product streams even if the plant is operated at high concentrations. This paper presents the experimental implementation of the ‘cycle to cycle’ control concept to the separation of guaifenesin enantiomers under nonlinear chromatographic conditions, i.e. at high feed concentrations. Different case studies have been carried out to challenge the controller under realistic operation conditions, e.g. introducing pump disturbances and changing the feed concentration during the operation. The experimental results clearly demonstrate that the controller can indeed deliver the specified purities and improve the process performance. 相似文献
227.
Qian Li 《Discrete Mathematics》2008,308(21):4846-4860
Li et al. [On the period and base of a sign pattern matrix, Linear Algebra Appl. 212/213 (1994) 101-120.] extended the concepts of the base and period from nonnegative matrices to powerful sign pattern matrices. Then, Shao and You [Bound on the basis of irreducible generalized sign pattern matrices, Linear Algebra Appl. 427 (2007) 285-300.] extended the concepts of the base from powerful sign pattern matrices to non-powerful irreducible sign pattern matrices. In this paper we mainly study the kth multi-g base index for non-powerful primitive nearly reducible sign pattern matrices. We obtain sharp upper bounds, together with a complete characterization of the equality cases of the kth multi-g base index for primitive nearly reducible generalized sign pattern matrices. We also show that there exist “gaps” in the kth multi-g base index set of the classes of such matrices. 相似文献
228.
具有一个高阶奇点和两个零特征根的一类多项式系统 总被引:2,自引:0,他引:2
韩玉良 《高校应用数学学报(A辑)》1996,(3):269-276
本文讨论了具有一个高阶奇点和两个零特征根的一类2n+1次系统,证明了这类系统可以存在两个n阶细焦点,给出极限存在性和不存在性的条件,并证明了无穷远分界线环的存在性。 相似文献
229.
陈文成 《高校应用数学学报(A辑)》1993,(2)
本文讨论具有有限多个奇点的广义Liénard系统解的有界性,得到一组保证系统的解正向有界的充分条件,进而得到存在极限环的条件。 相似文献
230.