全文获取类型
收费全文 | 1333篇 |
免费 | 122篇 |
国内免费 | 94篇 |
专业分类
化学 | 10篇 |
力学 | 9篇 |
综合类 | 11篇 |
数学 | 1487篇 |
物理学 | 32篇 |
出版年
2024年 | 2篇 |
2023年 | 24篇 |
2022年 | 33篇 |
2021年 | 22篇 |
2020年 | 60篇 |
2019年 | 48篇 |
2018年 | 47篇 |
2017年 | 40篇 |
2016年 | 28篇 |
2015年 | 29篇 |
2014年 | 60篇 |
2013年 | 120篇 |
2012年 | 70篇 |
2011年 | 108篇 |
2010年 | 93篇 |
2009年 | 138篇 |
2008年 | 106篇 |
2007年 | 62篇 |
2006年 | 101篇 |
2005年 | 60篇 |
2004年 | 45篇 |
2003年 | 42篇 |
2002年 | 37篇 |
2001年 | 27篇 |
2000年 | 29篇 |
1999年 | 28篇 |
1998年 | 25篇 |
1997年 | 21篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 3篇 |
1976年 | 1篇 |
排序方式: 共有1549条查询结果,搜索用时 31 毫秒
31.
Truemper configurations (thetas, pyramids, prisms, and wheels) have played an important role in the study of complex hereditary graph classes (eg, the class of perfect graphs and the class of even-hole-free graphs), appearing both as excluded configurations, and as configurations around which graphs can be decomposed. In this paper, we study the structure of graphs that contain (as induced subgraphs) no Truemper configurations other than (possibly) universal wheels and twin wheels. We also study several subclasses of this class. We use our structural results to analyze the complexity of the recognition, maximum weight clique, maximum weight stable set, and optimal vertex coloring problems for these classes. Furthermore, we obtain polynomial -bounding functions for these classes. 相似文献
32.
33.
34.
35.
任颜波 《数学年刊A辑(中文版)》2015,36(2):119-128
对3类由凹函数生成的弱Orlicz鞅空间建立了相应的弱原子分解.作为应用,首先给出了这些弱Orlicz鞅空间上次线性算子有界的一个充分条件,并在此基础上证明了一些弱型鞅不等式,然后证明了关于这些弱Orlicz鞅空间的Marcinkiewicz型插值定理. 相似文献
36.
37.
In this letter, we propose a new approach to obtain the smallest box which bounds all reachable sets of a class of nonlinear time-delay systems with bounded disturbances. A numerical example is studied to illustrate the obtained result. 相似文献
38.
András Gyárfás 《组合设计杂志》2015,23(8):321-327
A cross‐free set of size m in a Steiner triple system is three pairwise disjoint m‐element subsets such that no intersects all the three ‐s. We conjecture that for every admissible n there is an STS(n) with a cross‐free set of size which if true, is best possible. We prove this conjecture for the case , constructing an STS containing a cross‐free set of size 6k. We note that some of the 3‐bichromatic STSs, constructed by Colbourn, Dinitz, and Rosa, have cross‐free sets of size close to 6k (but cannot have size exactly 6k). The constructed STS shows that equality is possible for in the following result: in every 3‐coloring of the blocks of any Steiner triple system STS(n) there is a monochromatic connected component of size at least (we conjecture that equality holds for every admissible n). The analog problem can be asked for r‐colorings as well, if and is a prime power, we show that the answer is the same as in case of complete graphs: in every r‐coloring of the blocks of any STS(n), there is a monochromatic connected component with at least points, and this is sharp for infinitely many n. 相似文献
39.
40.