全文获取类型
收费全文 | 101941篇 |
免费 | 4436篇 |
国内免费 | 2735篇 |
专业分类
化学 | 41166篇 |
晶体学 | 1073篇 |
力学 | 8129篇 |
综合类 | 109篇 |
数学 | 34557篇 |
物理学 | 24078篇 |
出版年
2024年 | 70篇 |
2023年 | 523篇 |
2022年 | 946篇 |
2021年 | 908篇 |
2020年 | 1006篇 |
2019年 | 992篇 |
2018年 | 11031篇 |
2017年 | 10807篇 |
2016年 | 7134篇 |
2015年 | 1970篇 |
2014年 | 1620篇 |
2013年 | 2080篇 |
2012年 | 6080篇 |
2011年 | 12698篇 |
2010年 | 7104篇 |
2009年 | 7412篇 |
2008年 | 8116篇 |
2007年 | 10125篇 |
2006年 | 1551篇 |
2005年 | 2415篇 |
2004年 | 2331篇 |
2003年 | 2583篇 |
2002年 | 1599篇 |
2001年 | 681篇 |
2000年 | 718篇 |
1999年 | 662篇 |
1998年 | 613篇 |
1997年 | 578篇 |
1996年 | 645篇 |
1995年 | 473篇 |
1994年 | 380篇 |
1993年 | 326篇 |
1992年 | 286篇 |
1991年 | 260篇 |
1990年 | 218篇 |
1989年 | 202篇 |
1988年 | 156篇 |
1987年 | 166篇 |
1986年 | 144篇 |
1985年 | 128篇 |
1984年 | 89篇 |
1983年 | 79篇 |
1982年 | 76篇 |
1981年 | 56篇 |
1980年 | 57篇 |
1979年 | 54篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
33.
34.
35.
36.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献
37.
38.
Xiao Sun Li Zhang Yu Cao Jinhua Li Atanas G. Atanasov Linfang Huang 《Biomedical chromatography : BMC》2020,34(12):e4949
Balanophora involucrata J. D. Hooker has been known to possess potential anti-inflammatory and antibacterial activities; however, its antiviral activity has not been evaluated so far. In order to find new neuraminidase inhibitors (NAIs), the neuraminidase (NA) inhibition activity of different B. involucrata extracts was evaluated. In this study, an in vitro NA inhibition assay was performed to identify which extract of B. involucrata exhibits (maximal) inhibitory activity against NA. Ultra high performance liquid chromatography/quadrupole time-of-flight–tandem mass spectroscopy (MS/MS) and molecular docking techniques were used to identify the specific compounds responsible for the anti-influenza activity of the extract, and to explore the potential natural NAIs. The ethyl acetate extract of B. involucrata exhibited significant inhibitory activity against NA with 50% inhibitory concentration (IC50) value of 159.5 μg/mL. Twenty compounds were identified according to the MS/MS spectra; among them two compounds (quercitrin and phloridzin) showed obvious inhibitory activity against NA, with IC50 of 311.76 and 347.32 μmol/L, respectively. This study suggested that B. involucrata can be a potential natural source of NAIs and may be useful in the fight against ferocious influenza viruses. 相似文献
39.
40.
Yaping Chen Dr. Kun Rui Prof. Jixin Zhu Prof. Shi Xue Dou Dr. Wenping Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(3):703-713
Developing clean and sustainable energies as alternatives to fossil fuels is in strong demand within modern society. The oxygen evolution reaction (OER) is the efficiency-limiting process in plenty of key renewable energy systems, such as electrochemical water splitting and rechargeable metal–air batteries. In this regard, ongoing efforts have been devoted to seeking high-performance electrocatalysts for enhanced energy conversion efficiency. Apart from traditional precious-metal-based catalysts, nickel-based compounds are the most promising earth-abundant OER catalysts, attracting ever-increasing interest due to high activity and stability. In this review, the recent progress on nickel-based oxide and (oxy)hydroxide composites for water oxidation catalysis in terms of materials design/synthesis and electrochemical performance is summarized. Some underlying mechanisms to profoundly understand the catalytic active sites are also highlighted. In addition, the future research trends and perspectives on the development of Ni-based OER electrocatalysts are discussed. 相似文献