全文获取类型
收费全文 | 38028篇 |
免费 | 18166篇 |
国内免费 | 78篇 |
专业分类
化学 | 53182篇 |
晶体学 | 37篇 |
力学 | 1093篇 |
数学 | 1208篇 |
物理学 | 752篇 |
出版年
2024年 | 171篇 |
2023年 | 4240篇 |
2022年 | 1394篇 |
2021年 | 2406篇 |
2020年 | 4670篇 |
2019年 | 2219篇 |
2018年 | 2370篇 |
2017年 | 602篇 |
2016年 | 5542篇 |
2015年 | 5503篇 |
2014年 | 4921篇 |
2013年 | 5088篇 |
2012年 | 3060篇 |
2011年 | 1004篇 |
2010年 | 3321篇 |
2009年 | 3264篇 |
2008年 | 1044篇 |
2007年 | 741篇 |
2006年 | 202篇 |
2005年 | 147篇 |
2004年 | 104篇 |
2003年 | 104篇 |
2002年 | 71篇 |
1997年 | 62篇 |
1996年 | 69篇 |
1995年 | 137篇 |
1994年 | 80篇 |
1993年 | 196篇 |
1992年 | 98篇 |
1991年 | 70篇 |
1988年 | 97篇 |
1987年 | 79篇 |
1985年 | 66篇 |
1984年 | 86篇 |
1983年 | 74篇 |
1982年 | 91篇 |
1981年 | 98篇 |
1980年 | 111篇 |
1979年 | 116篇 |
1978年 | 118篇 |
1977年 | 184篇 |
1976年 | 190篇 |
1975年 | 191篇 |
1974年 | 203篇 |
1973年 | 118篇 |
1972年 | 157篇 |
1971年 | 125篇 |
1970年 | 213篇 |
1969年 | 129篇 |
1968年 | 138篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
Dr. Ngoc-Anh Tran Nhan Do Van Thanh Prof. My Loan Phung Le 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9198-9217
Magnesium batteries, like lithium-ion batteries, with higher abundance and similar efficiency, have drawn great interest for large-scale applications such as electric vehicles, grid energy storage and many more. On the other hand, the use of organic electrode materials allows high energy-performance, metal-free, environmentally friendly, versatile, lightweight, and economically efficient magnesium storage devices. In particular, the structural diversity and the simple activity of organic molecules make redox properties, and hence battery efficiency, easy to monitor. While organic magnesium batteries still in their infancy, this field becomes more and more promising because significant results were reported. To summarize the achievements in studies on organic cathodes for magnesium systems, their synthesis is discussed, combined with electrode design to provide the basis for controlling the electrochemical properties. Moreover, the techniques to synthesize organic materials with high-yield are mentioned. Finally, potential problems and prospects are explored to further improve organic cathodes. 相似文献
962.
963.
Christian A. Malapit Donald R. Caldwell Irungu K. Luvaga Dr. Jonathan T. Reeves Dr. Ivan Volchkov Dr. Nina C. Gonnella Dr. Zhengxu S. Han Dr. Carl A. Busacca Prof. Dr. Amy R. Howell Dr. Chris H. Senanayake 《Angewandte Chemie (International ed. in English)》2017,56(24):6999-7002
β-Ketonitriles bearing a quaternary carbon at the 2-position were prepared through Rh-catalyzed addition of aryl boronic acids to 2,2-disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro-Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β-ketonitriles. The products could be further derivatized to valuable chiral α,α-disubstituted-β-aminonitriles through addition reactions to the corresponding N-tert-butanesulfinyl imines. 相似文献
964.
965.
966.
967.
968.
969.
970.
Heping Deng Wei Cao Rong Liu Yanhui Zhang Prof. Dr. Bo Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5943-5946
Asymmetric total synthesis of the dimeric diterpenoid hispidanin A was accomplished by non-catalytic Diels–Alder cycloaddition at room temperature. The synthesis relies on iron-catalyzed coupling to construct a Z-configured trisubstituted alkene, an iron-catalyzed radical cascade to generate a labdane-type diene, and both Yamamoto cationic polyene cyclization and palladium-catalyzed Stille coupling to generate a totarane-type dienophile. 相似文献