全文获取类型
收费全文 | 4421篇 |
免费 | 158篇 |
国内免费 | 34篇 |
专业分类
化学 | 2695篇 |
晶体学 | 25篇 |
力学 | 125篇 |
数学 | 646篇 |
物理学 | 1122篇 |
出版年
2023年 | 22篇 |
2022年 | 72篇 |
2021年 | 151篇 |
2020年 | 101篇 |
2019年 | 157篇 |
2018年 | 146篇 |
2017年 | 130篇 |
2016年 | 189篇 |
2015年 | 138篇 |
2014年 | 174篇 |
2013年 | 238篇 |
2012年 | 317篇 |
2011年 | 353篇 |
2010年 | 196篇 |
2009年 | 194篇 |
2008年 | 293篇 |
2007年 | 263篇 |
2006年 | 230篇 |
2005年 | 208篇 |
2004年 | 168篇 |
2003年 | 115篇 |
2002年 | 116篇 |
2001年 | 64篇 |
2000年 | 44篇 |
1999年 | 40篇 |
1998年 | 40篇 |
1997年 | 44篇 |
1996年 | 35篇 |
1995年 | 28篇 |
1994年 | 14篇 |
1993年 | 21篇 |
1992年 | 11篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 19篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 17篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1979年 | 10篇 |
1977年 | 19篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 15篇 |
1973年 | 13篇 |
1970年 | 11篇 |
1969年 | 11篇 |
排序方式: 共有4613条查询结果,搜索用时 375 毫秒
161.
162.
163.
Sergey A. Cherkis 《Letters in Mathematical Physics》2015,105(5):641-659
164.
Sergey A. Nazarov Andrey S. Slutskij Jari Taskinen 《Mathematical Methods in the Applied Sciences》2014,37(16):2463-2483
We consider an elastic rod with rounded ends and diameter proportional to a small parameter h > 0. The roundness of the ends is described by an exponent m ∈ (0,1). We derive for the rod an asymptotically sharp Korn inequality with a special weighted anisotropic norm. Weight factors with m‐dependent powers of h appear both in the anisotropic norm and the Korn inequality itself, and we discover three critical values m = 1 ∕ 4, m = 1 ∕ 2 and m = 3 ∕ 4 at which these exponents are crucially changed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
165.
166.
Molecular dynamics simulation of poly(3‐hexylthiophene) helical structure In Vacuo and in amorphous polymer surrounding 下载免费PDF全文
Natalia I. Borzdun Sergey V. Larin Stanislav G. Falkovich Victor M. Nazarychev Igor V. Volgin Alexander V. Yakimansky Alexey V. Lyulin Vikas Negi Peter A. Bobbert Sergey V. Lyulin 《Journal of Polymer Science.Polymer Physics》2016,54(23):2448-2456
The stability of poly(3‐hexylthiophene) (P3HT) helical structure has been investigated in vacuo and in amorphous polymer surrounding via molecular dynamics‐based simulations at temperatures below and above the P3HT melting point. The results show that the helical chain remains stable at room temperature both in vacuo and in amorphous surrounding, and promptly loses its structure at elevated temperatures. However, the amorphous surrounding inhibits the destruction of the helix at higher temperatures. In addition, it is shown that the electrostatic interactions do not significantly affect the stability of the helical structure. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2448–2456 相似文献
167.
Kirill V. Zaitsev Yulia A. Piskun Yuri F. Oprunenko Sergey S. Karlov Galina S. Zaitseva Irina V. Vasilenko Andrei V. Churakov Sergei V. Kostjuk 《Journal of polymer science. Part A, Polymer chemistry》2014,52(9):1237-1250
The aluminum complexes containing two iminophenolate ligands of the type (p‐XC6H4NCHC6H4O‐o)2AlR' (R′=Me ( 3, 4 ) or R′=O(CH2)4OCH=CH2 ( 5, 6 ), X=H ( 3, 5 ), F( 4, 6 )) were synthesized and characterized by 1H, 13C NMR spectroscopy, and X‐ray crystallography. The reaction of AlMe3 with two equivalents of substituted iminophenols gave five‐coordinated {ONR}2AlMe ( 3, 4 ) complexes. Subsequent reaction of these methyl complexes with unsaturated alcohol, HO(CH2)4OCH=CH2, resulted in target compounds 5 and 6 in a good yield. It was shown that the complexes ( 3 ‐ 6 ) are monomeric in solution (NMR) and in solid state (X‐ray analysis). The catalytic activity of the complexes 5 and 6 towards ring‐opening polymerization (ROP) of ?‐caprolactone and d,l ‐lactide was assessed. Complex 5 showed higher activity as compared with 6 , while both of these catalysts induced controlled homo‐ and copolymerization to afford the macromonomers with high content of vinyl ether end groups (Fn > 80%) in a broad range of molecular weights (Mn = 4000–30,000 g mol?1) with relatively narrow MWD (Mw/Mn = 1.1–1.5). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1237–1250 相似文献
168.
169.
170.
Sautenkov Vladimir A. Saakyan Sergey A. Zelener Boris B. 《Journal of Russian Laser Research》2021,42(4):405-411
Journal of Russian Laser Research - We discuss the experimental research of an optical resonant saturation of a dipole–dipole-broadened atomic transition in the high-density rubidium vapor.... 相似文献