全文获取类型
收费全文 | 282154篇 |
免费 | 5261篇 |
国内免费 | 3315篇 |
专业分类
化学 | 131622篇 |
晶体学 | 3201篇 |
力学 | 17735篇 |
综合类 | 280篇 |
数学 | 55487篇 |
物理学 | 82405篇 |
出版年
2021年 | 2561篇 |
2020年 | 2944篇 |
2019年 | 3341篇 |
2018年 | 14300篇 |
2017年 | 14161篇 |
2016年 | 11218篇 |
2015年 | 3825篇 |
2014年 | 5327篇 |
2013年 | 9302篇 |
2012年 | 11682篇 |
2011年 | 19327篇 |
2010年 | 12591篇 |
2009年 | 13089篇 |
2008年 | 14465篇 |
2007年 | 16403篇 |
2006年 | 7278篇 |
2005年 | 7421篇 |
2004年 | 7184篇 |
2003年 | 7047篇 |
2002年 | 6204篇 |
2001年 | 5778篇 |
2000年 | 4524篇 |
1999年 | 3605篇 |
1998年 | 3357篇 |
1997年 | 3130篇 |
1996年 | 2952篇 |
1995年 | 2620篇 |
1994年 | 2514篇 |
1993年 | 2470篇 |
1992年 | 2449篇 |
1991年 | 2719篇 |
1990年 | 2563篇 |
1989年 | 2601篇 |
1988年 | 2446篇 |
1987年 | 2466篇 |
1986年 | 2277篇 |
1985年 | 2792篇 |
1984年 | 2758篇 |
1983年 | 2383篇 |
1982年 | 2431篇 |
1981年 | 2326篇 |
1980年 | 2116篇 |
1979年 | 2423篇 |
1978年 | 2581篇 |
1977年 | 2666篇 |
1976年 | 2742篇 |
1975年 | 2561篇 |
1974年 | 2489篇 |
1973年 | 2661篇 |
1972年 | 2166篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
AbstractIn this study, the photovoltaic organic-inorganic structures were created by deposition of poly(3,4-ethylenedioxythiophene) film doped by poly(styrenesulfonate) and reduced graphene oxide on the porous silicon/silicon substrate. Formation of the hybrid structure was confirmed by means of atomic-force microscopy and Fourier transform infrared spectroscopy. The current-voltage characteristics of the obtained structures were studied. It was found the increase of electrical conductivity and photo-induced signal in organic-inorganic structures. Temporal parameters and spectral characteristics of photoresponse in the 400–1100?nm wavelength range were investigated. The widening of spectral photosensitivity in a short-wavelength range due to light absorption in various layers of the multijunction structure in comparison with single crystal silicon was revealed. 相似文献
92.
93.
94.
95.
Sulfur hexafluoride (SF6) is considered as a potent greenhouse gas, whose effective degradation is challenging. Here we report a computational study on the nucleophilic activation of sulfur hexafluoride by N-heterocyclic carbenes and N-heterocyclic olefins. The result shows that the activation of SF6 is both thermodynamically and kinetically favorable at mild condition using NHOs with fluoro-substituted azolium and sulfur pentafluoride anion being formed. The Gibbs free energy barrier during the activation of SF6 has a linear relationship with the energy of HOMO of substrates, which could be a guideline for applying those compounds that feature higher energy in HOMO to activate SF6 in high efficiency. 相似文献
96.
97.
98.
99.
Belakhov V. V. Boikova I. V. Krasnobaeva I. L. Kolodyaznaya V. A. 《Russian Journal of General Chemistry》2021,91(13):2900-2907
Russian Journal of General Chemistry - A method was developed for the synthesis of an organofluorine derivative of β-D-ribofuranoside. Biological tests revealed high insecticidal activity and... 相似文献
100.
Technical Physics - A need to study the structure of the NMR signals detected with the aid of the modulation method is substantiated. Specific features of the detection of the NMR signals using the... 相似文献