全文获取类型
收费全文 | 48376篇 |
免费 | 3451篇 |
国内免费 | 3575篇 |
专业分类
化学 | 20918篇 |
晶体学 | 195篇 |
力学 | 1666篇 |
综合类 | 966篇 |
数学 | 19807篇 |
物理学 | 11850篇 |
出版年
2023年 | 421篇 |
2022年 | 586篇 |
2021年 | 1539篇 |
2020年 | 1124篇 |
2019年 | 1297篇 |
2018年 | 1015篇 |
2017年 | 1134篇 |
2016年 | 1290篇 |
2015年 | 1240篇 |
2014年 | 1865篇 |
2013年 | 3808篇 |
2012年 | 1954篇 |
2011年 | 2451篇 |
2010年 | 2280篇 |
2009年 | 2900篇 |
2008年 | 3075篇 |
2007年 | 3411篇 |
2006年 | 2622篇 |
2005年 | 1929篇 |
2004年 | 1719篇 |
2003年 | 1781篇 |
2002年 | 1682篇 |
2001年 | 1526篇 |
2000年 | 1152篇 |
1999年 | 981篇 |
1998年 | 975篇 |
1997年 | 756篇 |
1996年 | 758篇 |
1995年 | 615篇 |
1994年 | 603篇 |
1993年 | 592篇 |
1992年 | 579篇 |
1991年 | 412篇 |
1990年 | 312篇 |
1989年 | 275篇 |
1988年 | 290篇 |
1987年 | 243篇 |
1986年 | 248篇 |
1985年 | 377篇 |
1984年 | 272篇 |
1983年 | 168篇 |
1982年 | 319篇 |
1981年 | 497篇 |
1980年 | 448篇 |
1979年 | 485篇 |
1978年 | 391篇 |
1977年 | 303篇 |
1976年 | 249篇 |
1974年 | 81篇 |
1973年 | 159篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
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
22.
23.
《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
24.
《Arabian Journal of Chemistry》2022,15(10):104145
In the present study, novel representatives of the important group of biologically-active, dehydroabietic acid-bearing dithiocarbamate moiety, were synthesized and characterized by 1H NMR, 13C NMR, HR-MS. The in vitro antiproliferative activity evaluation (MTT) indicated that these compounds exhibited potent inhibitory activities in various cancer cell lines (HepG-2, MCF-7, HeLa, T-24, MGC-803). Particularly, compound III-b possessed extraordinary cytotoxicity with low micromolar IC50 values ranging from 4.07 to 38.84 µM against tested cancer cell lines, while displayed weak cytotoxicity on two normal cell lines (LO-2 and HEK 293 T). Subsequently, the potential mechanisms of representative compound III-b were elementarily investigated by Transwell experiment, which showed III-b can inhibit cancer cells migration. Annexin-V/PI dual staining showed that the compound can induce HepG-2 cells apoptosis in a dose-dependent manner. Meanwhile this apoptosis may be related to the upregulated protein expression of cleaved-caspase 3, cleaved-caspase 9, Bax and downregulated of Bcl-2 indicated by Western Blot. Later study further confirmed that ROS levels in HepG-2 cells increased significantly with the rise of concentrations. In addition, through the network pharmacology data analyzing, the core targets and signaling pathways of compound III-b for treatment of liver neoplasms were forecasted. Molecular docking model showed that compound III-b had high affinity with hub targets (CASP3, EGFR, HSP90AA1, MAPK1, ERBB2, MDM2), suggesting that compound III-b might target the hub protein to modulate signaling activity. Taken together, these data indicated that dehydroabietic acid structural modification following the “Molecular hybridization” principle is a feasible way to discover the potential multi-targeted antitumor compounds. 相似文献
25.
26.
27.
28.
29.
30.