全文获取类型
收费全文 | 1655篇 |
免费 | 68篇 |
国内免费 | 107篇 |
专业分类
化学 | 414篇 |
力学 | 64篇 |
综合类 | 17篇 |
数学 | 1088篇 |
物理学 | 247篇 |
出版年
2023年 | 17篇 |
2022年 | 36篇 |
2021年 | 21篇 |
2020年 | 47篇 |
2019年 | 41篇 |
2018年 | 38篇 |
2017年 | 41篇 |
2016年 | 30篇 |
2015年 | 24篇 |
2014年 | 36篇 |
2013年 | 96篇 |
2012年 | 99篇 |
2011年 | 87篇 |
2010年 | 77篇 |
2009年 | 99篇 |
2008年 | 101篇 |
2007年 | 134篇 |
2006年 | 101篇 |
2005年 | 80篇 |
2004年 | 65篇 |
2003年 | 64篇 |
2002年 | 57篇 |
2001年 | 55篇 |
2000年 | 49篇 |
1999年 | 49篇 |
1998年 | 41篇 |
1997年 | 45篇 |
1996年 | 28篇 |
1995年 | 23篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 3篇 |
排序方式: 共有1830条查询结果,搜索用时 390 毫秒
991.
After constructing the Bethe state of the XXZ Gaudin model with generic non-diagonal boundary terms, we analyze the properties of this state and obtain the determinant representations of the scalar products for this XXZ Gaudin model. 相似文献
992.
Let be the complete symmetric digraph on the positive integers. Answering a question of DeBiasio and McKenney, we construct a 2-colouring of the edges of in which every monochromatic path has density 0.However, if we restrict the length of monochromatic paths in one colour, then no example as above can exist: We show that every -edge-coloured complete symmetric digraph (of arbitrary infinite cardinality) containing no directed paths of edge-length for any colour can be covered by pairwise disjoint monochromatic complete symmetric digraphs in colour .Furthermore, we present a stability version for the countable case of the latter result: We prove that the edge-colouring is uniquely determined on a large subgraph, as soon as the upper density of monochromatic paths in colour is bounded by . 相似文献
993.
994.
995.
Frans Schalekamp András Sebő Vera Traub Anke van Zuylen 《Operations Research Letters》2018,46(1):60-63
Gottschalk and Vygen proved that every solution of the subtour elimination linear program for traveling salesman paths is a convex combination of more and more restrictive “generalized Gao-trees”. We give a short proof of this fact, as a layered convex combination of bases of a sequence of increasingly restrictive matroids. A strongly polynomial, combinatorial algorithm follows for finding this convex combination, which is a new tool offering polyhedral insight, already instrumental in recent results for the path TSP. 相似文献
996.
Assuming , the hierarchy of norms is a wellordered structure of equivalence classes of ordinal-valued maps. We define operations on the hierarchy of norms, in particular an operation that dominates multiplication as an operation on the ranks of norms, and use these operations to establish a considerably improved lower bound for the length of the hierarchy of norms. 相似文献
997.
《Discrete Mathematics》2020,343(9):111969
If two partitions are conjugate, their multisets of hook lengths are the same. Then one may wonder whether the multiset of hook lengths of a partition determines a partition up to conjugation. The answer turns out to be no. However, we may add an extra condition under which a given multiset of hook lengths determines a partition uniquely up to conjugation. Herman-Chung, and later Morotti found such a condition. We give an alternative proof of Morotti’s theorem and generalize it. 相似文献
998.
《Operations Research Letters》2020,48(5):558-565
In this paper, we first give a dual characterization for set containments defined by lower semi-continuous and sublinear functions on Banach spaces. Next, we provide dual characterizations for robust polyhedral containments where a robust counterpart of an uncertain polyhedral set is contained in another polyhedral set or a polyhedral set is contained in a robust counterpart of an uncertain polyhedral set. Finally, as an application, we derive Lagrange multiplier characterizations for robust solutions of the robust uncertain linear programming problems. 相似文献
999.
《组合设计杂志》2018,26(10):465-479
A cycle of length t in a hypergraph is an alternating sequence of distinct vertices and distinct edges so that (with ). Let be the λ‐fold n‐vertex complete h‐graph. Let be a hypergraph all of whose edges are of size at least h, and . In order to partition the edge set of into cycles of specified lengths , an obvious necessary condition is that . We show that this condition is sufficient in the following cases.
- (R1) .
- (R2) , .
- (R3) , , .
1000.
有限元法是数值求解三维弹性问题的一类重要的离散化方法,高次有限元又是其中的一类常用有限元。由于高次元对问题具有更好的逼近效果及具有某些特殊的优点,如能解决弹性问题的闭锁现象(Poisson’s ratio locking),使得它们在实际计算中被广泛使用。但与线性元相比,它具有更高的计算复杂性。通过分析高次有限元空间与线性有限元空间之间的关系,提出了一种求解三维弹性问题高次有限元方程的两水平方法,然后,通过调用现有的代数多层网格法求解粗水平方程,建立了求解高次有限元方程的AMG法。数值实验表明,本文设计的AMG法对求解三维弹性问题高次有限元方程具有很好的计算效率和鲁棒性。 相似文献