全文获取类型
收费全文 | 2151篇 |
免费 | 65篇 |
国内免费 | 17篇 |
专业分类
化学 | 1249篇 |
晶体学 | 15篇 |
力学 | 74篇 |
数学 | 536篇 |
物理学 | 359篇 |
出版年
2023年 | 8篇 |
2022年 | 64篇 |
2021年 | 86篇 |
2020年 | 66篇 |
2019年 | 58篇 |
2018年 | 72篇 |
2017年 | 42篇 |
2016年 | 85篇 |
2015年 | 77篇 |
2014年 | 84篇 |
2013年 | 148篇 |
2012年 | 135篇 |
2011年 | 159篇 |
2010年 | 100篇 |
2009年 | 85篇 |
2008年 | 108篇 |
2007年 | 87篇 |
2006年 | 100篇 |
2005年 | 76篇 |
2004年 | 68篇 |
2003年 | 40篇 |
2002年 | 61篇 |
2001年 | 23篇 |
2000年 | 30篇 |
1999年 | 17篇 |
1998年 | 15篇 |
1997年 | 17篇 |
1996年 | 20篇 |
1995年 | 24篇 |
1994年 | 17篇 |
1993年 | 21篇 |
1992年 | 18篇 |
1991年 | 24篇 |
1990年 | 17篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 17篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1976年 | 6篇 |
1970年 | 10篇 |
1969年 | 5篇 |
1968年 | 6篇 |
1967年 | 10篇 |
排序方式: 共有2233条查询结果,搜索用时 15 毫秒
61.
62.
Piotr Kulpinski Marek Namyslak Tomasz Grzyb Stefan Lis 《Cellulose (London, England)》2012,19(4):1271-1278
UV- active cellulose fibers were obtained by dry-wet method spinning an 8?% by weight α-cellulose solution in N-methylomorpholine-N-oxide (NMMO) modified by europium-doped gadolinium oxyfluoride Gd4O3F6:Eu3+ containing 5?mol (%) of the dopant. Photoluminescent nanoparticles were introduced in the in powder form into a polymer matrix during the process of cellulose dissolution in NMMO. The dependencies of emission intensity on excitation energy and the concentration of Gd4O3F6:Eu3+ nanoparticles in the final cellulosic products were examined by photoluminescence spectroscopy (excitation and emission). The fiber structure was studied by X-ray powder diffraction analysis. The size and dispersity of the nanoparticles in the polymer matrix were evaluated using scanning electron microscopy and X-ray microanalysis. The influence of different concentration particles (in the range from 0.5 to 5?% by weight) on the mechanical properties of the fibers, such as tenacity and elongation at break, were determined. 相似文献
63.
Falko Böttger‐Hiller Patrick Kempe Dr. Gerhard Cox Dr. Alexander Panchenko Dr. Nicole Janssen Dr. Albrecht Petzold Prof. Dr. Thomas Thurn‐Albrecht Lars Borchardt Dr. Marcus Rose Prof. Dr. Stefan Kaskel Colin Georgi Prof. Dr. Heinrich Lang Prof. Dr. Stefan Spange 《Angewandte Chemie (International ed. in English)》2013,52(23):6088-6091
64.
Tomasz Szostok 《Lithuanian Mathematical Journal》2018,58(1):95-103
We present a method of proving inequalities for convex functions with use of Stieltjes integral. First, we show how some well-known inequalities can be obtained, and then we show how new inequalities and stronger versions of some existing results can be obtained. 相似文献
65.
Tomasz Laskowski Zbigniew Rafiński Paweł Sowiński Jan Pawlak 《Magnetic resonance in chemistry : MRC》2012,50(5):347-349
The relative configurations of four stereogenic centers of the C33‐C42 fragment of niphimycin A were assigned as 2S*, 3R*, 4S* and 6S*, based upon 1H NMR analysis with double‐quantum filtered COSY and nuclear Overhauser spectroscopy experiments. These data were then correlated with absolute configurations at C36 and C38 of niphimycin A, which were declared previously as 36S and 38S [3]. This allowed for the assignment of the absolute configurations at C34 and C35 of niphimycin A as 34S and 35R. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
66.
67.
Pyrroles represent building blocks of conjugated poly(heterocycles) which, as organic conductors, are potential materials for organic electronics. Oxidation of β-substituted pyrroles constitutes an important first step in the process of electropolymerization. Ionization energy and the electron spin density distribution are two the most important properties regarding monomers. These properties are studied as a function of electron-withdrawing and electron-donating substituents of pyrrole ring. Evolution of molecular structure, nature of bonding, and electronic density are studied as an effect of ionization process. 相似文献
68.
69.
70.