全文获取类型
收费全文 | 482145篇 |
免费 | 3040篇 |
国内免费 | 719篇 |
专业分类
化学 | 222056篇 |
晶体学 | 6915篇 |
力学 | 27604篇 |
综合类 | 9篇 |
数学 | 73872篇 |
物理学 | 155448篇 |
出版年
2020年 | 4251篇 |
2019年 | 5049篇 |
2018年 | 12379篇 |
2017年 | 12789篇 |
2016年 | 12272篇 |
2015年 | 5149篇 |
2014年 | 8734篇 |
2013年 | 17491篇 |
2012年 | 16884篇 |
2011年 | 24644篇 |
2010年 | 17662篇 |
2009年 | 17994篇 |
2008年 | 22665篇 |
2007年 | 24853篇 |
2006年 | 14478篇 |
2005年 | 16141篇 |
2004年 | 13639篇 |
2003年 | 13048篇 |
2002年 | 12084篇 |
2001年 | 11264篇 |
2000年 | 9050篇 |
1999年 | 6665篇 |
1998年 | 6122篇 |
1997年 | 5913篇 |
1996年 | 5520篇 |
1995年 | 5007篇 |
1994年 | 5034篇 |
1993年 | 4915篇 |
1992年 | 5121篇 |
1991年 | 5629篇 |
1990年 | 5404篇 |
1989年 | 5409篇 |
1988年 | 5157篇 |
1987年 | 5152篇 |
1986年 | 4774篇 |
1985年 | 5795篇 |
1984年 | 6138篇 |
1983年 | 5197篇 |
1982年 | 5528篇 |
1981年 | 5122篇 |
1980年 | 4827篇 |
1979年 | 5400篇 |
1978年 | 5644篇 |
1977年 | 5567篇 |
1976年 | 5718篇 |
1975年 | 5344篇 |
1974年 | 5258篇 |
1973年 | 5457篇 |
1972年 | 4273篇 |
1971年 | 3854篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
A. Lashgari S. Ghammamy R. Ramirez-Tagle G. Salgado-Moran 《Journal of Structural Chemistry》2015,56(8):1505-1513
Two new compounds of fluorine: (C2H5)4N[I2F] and (C2H5)4N[Br2F], have been easily synthesized in a nearly quantitative by a direct reaction of (C2H5)4NF, I2 and Br2. The products were isolated and characterized by elemental analysis and spectroscopic methods such as: Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). These compounds have been studied computationally with the Scalar ZORA relativistic level of theory using the ADF program package. The molecular parameters, and vibrational spectra were calculated. The excitation energies were found by timedependent perturbation density functional theory (TD-DFT). Molecule optimization, frequencies and excitation energies were calculated with standard Slatertype-orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all atoms. The FTIR, UV-Vis spectra and assignment of principal transitions and total density of state (TDOS) were extracted using the GaussSum 2.2 program. The comparison between experimental and calculated values showes that the experimental results correlate well with the predicted data. 相似文献
102.
Development of biocompatible porous supports is a promising strategy in the field of tissue engineering for the repair and regeneration of bone tissues with severe damage. Graphene oxide aerogels (GOAs) are excellent candidates for the manufacture of these systems due to their porosity, ability to imitate bone structure, and mechanical resistance, and according to their surface chemical reactivity, they can facilitate osseointegration, osteogenesis, osteoinduction and osteoconduction. In this review, synthesis of GOAs from the most primary source is described, and recent studies on the use of these functionalized carbonaceous foams as scaffolding for bone tissue regeneration are presented. 相似文献
103.
Journal of Thermal Analysis and Calorimetry - In the present work, pyrolysis kinetic mechanism was studied for regenerated cellulosic fiber (RCF) and composite RCF containing silicon/nitrogen flame... 相似文献
104.
Colloid Journal - An Erratum to this paper has been published: https://doi.org/10.1134/S1061933X21330024 相似文献
105.
Vyacheslav V. Sentyurin Oleg A. Levitskiy Tatiana V. Magdesieva 《Current Opinion in Electrochemistry》2020
This mini-review highlights key structural features that should be taken into account when creating ambipolar redox-active closed-shell metal-free molecules. This type of compound is strongly required for the fabrication of all-organic ‘poleless’ batteries and semiconductors. The suggested strategies aimed at stabilization of both oxidized (cationic) and reduced (anionic) redox-states are based on the comprehensive analysis of the most successful structures taken from the recent publications. 相似文献
106.
107.
108.
109.
110.
Journal of Thermal Analysis and Calorimetry - Low productivity of single-slope solar still is the main barrier for its worldwide usability. An attempt has been conducted to enhance the distillate... 相似文献