全文获取类型
收费全文 | 9652篇 |
免费 | 685篇 |
国内免费 | 799篇 |
专业分类
化学 | 465篇 |
晶体学 | 6篇 |
力学 | 51篇 |
综合类 | 150篇 |
数学 | 5527篇 |
物理学 | 370篇 |
综合类 | 4567篇 |
出版年
2024年 | 34篇 |
2023年 | 151篇 |
2022年 | 224篇 |
2021年 | 198篇 |
2020年 | 269篇 |
2019年 | 290篇 |
2018年 | 282篇 |
2017年 | 265篇 |
2016年 | 185篇 |
2015年 | 200篇 |
2014年 | 375篇 |
2013年 | 604篇 |
2012年 | 444篇 |
2011年 | 536篇 |
2010年 | 478篇 |
2009年 | 658篇 |
2008年 | 607篇 |
2007年 | 604篇 |
2006年 | 615篇 |
2005年 | 480篇 |
2004年 | 437篇 |
2003年 | 373篇 |
2002年 | 344篇 |
2001年 | 327篇 |
2000年 | 312篇 |
1999年 | 290篇 |
1998年 | 251篇 |
1997年 | 188篇 |
1996年 | 160篇 |
1995年 | 160篇 |
1994年 | 128篇 |
1993年 | 111篇 |
1992年 | 118篇 |
1991年 | 94篇 |
1990年 | 75篇 |
1989年 | 79篇 |
1988年 | 61篇 |
1987年 | 45篇 |
1986年 | 23篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1967年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
1.
Yuanbo Gao Tingting Yang Xueli Wang Jizong Chen Yong He 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1610-1623
Two series of novel alternating copolyoxamides (PAnT-alt-n2 and PAn2-alt-62) are synthesized via solution/solid-state polycondensation (SSP). The alternating structures are analyzed carefully with 1H NMR and 13C NMR spectra. The melting behaviors, thermal stabilities, crystal structures and crystallinities are systematically evaluated by DSC, TGA and WAXD. The results reveal that these alternating copolyoxamides possess almost perfect alternating chain structures and have high melting temperature (Tm > 270 °C), high crystallinity (Xc > 32%) and high decomposition temperature (T5 > 405 °C) as well as low saturated water absorption (<3.5 wt%), which suggests that they have high potential as engineering plastic of high heat resistant. 相似文献
2.
Rose Morris-Wright 《Journal of Pure and Applied Algebra》2021,225(1):106468
Parabolic subgroups are the building blocks of Artin groups. This paper extends previous results of Cumplido, Gebhardt, Gonzales-Meneses and Wiest, known only for parabolic subgroups of finite type Artin groups, to parabolic subgroups of FC-type Artin groups. We show that the class of finite type parabolic subgroups is closed under intersection. We also study an analog of the curve complex for mapping class group constructed by Cumplido et al. using parabolic subgroups. We extend the construction of this complex, called the complex of parabolic subgroups, to FC-type Artin groups. We show that this simplicial complex is, in most cases, infinite diameter and conjecture that it is δ-hyperbolic. 相似文献
3.
《Discrete Mathematics》2022,345(10):112984
Let G be a generalized dicyclic group with identity 1. An inverse closed subset S of is called minimal if and there exists some such that . In this paper, we characterize distance-regular Cayley graphs of G under the condition that S is minimal. 相似文献
4.
6.
7.
8.
9.
《Discrete Mathematics》2020,343(12):112117
Let be an edge-colored graph of order . The minimum color degree of , denoted by , is the largest integer such that for every vertex , there are at least distinct colors on edges incident to . We say that an edge-colored graph is rainbow if all its edges have different colors. In this paper, we consider vertex-disjoint rainbow triangles in edge-colored graphs. Li (2013) showed that if , then contains a rainbow triangle and the lower bound is tight. Motivated by this result, we prove that if and , then contains two vertex-disjoint rainbow triangles. In particular, we conjecture that if , then contains vertex-disjoint rainbow triangles. For any integer , we show that if and , then contains vertex-disjoint rainbow triangles. Moreover, we provide sufficient conditions for the existence of edge-disjoint rainbow triangles. 相似文献
10.
本文通过组合数学和矩阵论的方法获得了完全图的特征多项式和谱,指出完全图的特征多项式的系数与图的结构之间的关系,并证明了邻接谱、拉谱拉斯谱和无符号拉谱拉斯谱三者之间的关系. 相似文献