全文获取类型
收费全文 | 188563篇 |
免费 | 5700篇 |
国内免费 | 3086篇 |
专业分类
化学 | 104563篇 |
晶体学 | 2345篇 |
力学 | 9014篇 |
综合类 | 203篇 |
数学 | 19948篇 |
物理学 | 61276篇 |
出版年
2021年 | 1648篇 |
2020年 | 1916篇 |
2019年 | 1898篇 |
2018年 | 1803篇 |
2017年 | 1720篇 |
2016年 | 3258篇 |
2015年 | 2854篇 |
2014年 | 3585篇 |
2013年 | 9139篇 |
2012年 | 7966篇 |
2011年 | 9827篇 |
2010年 | 6093篇 |
2009年 | 6188篇 |
2008年 | 8464篇 |
2007年 | 8365篇 |
2006年 | 8065篇 |
2005年 | 7416篇 |
2004年 | 6643篇 |
2003年 | 5625篇 |
2002年 | 5502篇 |
2001年 | 6491篇 |
2000年 | 4990篇 |
1999年 | 3885篇 |
1998年 | 2988篇 |
1997年 | 2871篇 |
1996年 | 2617篇 |
1995年 | 2513篇 |
1994年 | 2390篇 |
1993年 | 2182篇 |
1992年 | 2525篇 |
1991年 | 2447篇 |
1990年 | 2146篇 |
1989年 | 2097篇 |
1988年 | 2079篇 |
1987年 | 1998篇 |
1986年 | 1900篇 |
1985年 | 2818篇 |
1984年 | 2764篇 |
1983年 | 2213篇 |
1982年 | 2390篇 |
1981年 | 2264篇 |
1980年 | 2214篇 |
1979年 | 2159篇 |
1978年 | 2227篇 |
1977年 | 2189篇 |
1976年 | 2119篇 |
1975年 | 2108篇 |
1974年 | 2016篇 |
1973年 | 2095篇 |
1972年 | 1188篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
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
43.
S. Q. Hou W. Wang Z. Y. Wang Z. W. Hu K. Liu 《Journal of Applied Mechanics and Technical Physics》2018,59(1):153-162
In order to investigate the characteristics of force chains in a granular flow system, a parallel plate shear cell is constructed to simulate the shear movement of an infinite parallel plate and observe variations in relevant parameters. The shear dilatancy process is divided into three stages, namely, plastic strain, macroscopic failure, and granular recombination. The stickslip phenomenon is highly connected with the evolution of force chains during the shear dilatancy process. The load–distribution rate curves and patterns of the force chains are utilized to describe the load-carrying behaviors and morphologic changes of force chains separately. Force chains, namely, “diagonal gridding,” “tadpole-shaped,” and “pinnate” are defined according to the form of the force chains in the corresponding three stages. 相似文献
44.
45.
46.
Thalia Tsiaka Panagiotis Zoumpoulakis Vassilia J. Sinanoglou Constantinos Makris Georgios A. Heropoulos Antony C. Calokerinos 《Analytica chimica acta》2015
High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE. 相似文献
47.
48.
Echabaane M. Hfaiedh S. Smiri B. Saidi F. Dridi C. 《Journal of Solid State Electrochemistry》2021,25(6):1797-1806
Journal of Solid State Electrochemistry - The fast and sensitive detection of copper ions would be essential for water monitoring. Herein, we report a novel development of an impedimetric sensor... 相似文献
49.
50.
A model with 16 moments is here presented in the framework of RET of polyatomic gases. It furnishes as principal subsystem the relativistic counterpart of a work by Arima T., Ruggeri T., Sugiyama M.; this is present in literature and treats the non relativistic case which incorporates relaxation processes of molecular rotation and vibration. Another principal subsystem is the natural extension of the 14 moments model by Pennisi S. and Ruggeri T.; this is also present in literature in the relativistic framework but where the trace of the third balance equation is neglected. Its extension is found here for the case when this trace isn’t neglected.
相似文献