全文获取类型
收费全文 | 960篇 |
免费 | 41篇 |
国内免费 | 2篇 |
学科分类
数理化 | 1003篇 |
出版年
2023年 | 8篇 |
2022年 | 5篇 |
2021年 | 24篇 |
2020年 | 18篇 |
2019年 | 17篇 |
2018年 | 20篇 |
2017年 | 24篇 |
2016年 | 24篇 |
2015年 | 28篇 |
2014年 | 22篇 |
2013年 | 31篇 |
2012年 | 60篇 |
2011年 | 48篇 |
2010年 | 28篇 |
2009年 | 13篇 |
2008年 | 41篇 |
2007年 | 32篇 |
2006年 | 27篇 |
2005年 | 93篇 |
2004年 | 92篇 |
2003年 | 61篇 |
2002年 | 24篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 4篇 |
1989年 | 5篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1981年 | 7篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1974年 | 8篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1962年 | 3篇 |
1949年 | 3篇 |
1948年 | 14篇 |
排序方式: 共有1003条查询结果,搜索用时 15 毫秒
1.
Franck D'Agosto Marie‐Thrse Charreyre Christian Pichot Robert G. Gilbert 《Journal of polymer science. Part A, Polymer chemistry》2003,41(9):1188-1195
A method is described for synthesizing latex particles with anchored hairs by the grafting of hydrophilic chains, synthesized by reversible addition–fragmentation chain transfer, onto functionalized latex particles. These have the potential to bind biologically active species. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1188–1195, 2003 相似文献
2.
3.
4.
E. Possenriede P. Jacobs H. Kröse O. F. Schirmer 《Applied Physics A: Materials Science & Processing》1992,55(1):73-81
On the basis of a previous identification of paramagnetic defects in nominally undoped as grown BaTiO3 single crystals, we have investigated the changes of the concentrations of these centers and their optical absorptions under illumination with light of varying wavelengths. The most pronounced charge transfers occur by hole ionization of Fe4+ and — to a lesser extent — of Cr5+ and Cr4+. At low temperatures the created holes are trapped in the form of O–-ions next to Al3+ or unknown acceptor defects. Corresponding Fe4+ and O– absorptions have been identified. 相似文献
5.
6.
The kinetics and the equilibrium constant of the chlorine transfer reaction between monochloramine NH2Cl and the amines: C2H5NH2, (CH3)2CHNH2, (CH3)2NH, and (C2H5)2NH are investigated by spectrophotometry in aqueous medium at 25°C, in the pH range from 8 to 13 and for an ionic strength equal to 1.03 ± 0.05M. For a concentration of total ammonia equal to 1M, the observed rate constant is pH independent below 8 and above 12.8 and reaches a maximum located between the pKas of NH4+ and RR'NH2+. From these results and those obtained earlier for NH2Cl and CH3NH2, the reaction is shown to involve an interaction between neutral molecules NH2Cl and RR'NH, subject to general acid catalysis. The ability of an interaction corresponding to a specific catalysis and involving NH3Cl+ and RR'NH rather than NH2Cl and RR'NH2+ is also discussed. The activation parameters are given for each reaction. 相似文献
7.
A striking size dependence of the mean-square displacement of diffusing particles in the two-dimensional lattice gas of hard squares has been observed by Monte Carlo simulation. It is shown that the size effect is due to the formation of a stable cage structure in small lattices when the particle concentration is high. The formation of cages is governed by a new type of percolation problem related to bootstrap percolation. 相似文献
8.
A. Varinlioĝlu A. Köse U. Çevik A. I. Kopya M. Altunbaş H. Karal 《Journal of Radioanalytical and Nuclear Chemistry》1995,201(1):31-37
Sediment samples collected from the Eastern Black Sea in 1993 from 15 sampling stations of different depths have been analyzed. Natural and artifical radionuclide activity levels in offshore sediment samples from the Eastern Black Sea in Turkey are reported about seven years after the Chernobyl accident. The purpose of this paper is to follow up the earlier study and present results for the distributions of radionuclides in sediments of the Black Sea. 相似文献
9.
The recently discovered intramolecular aza-xylylene Diels-Alder reaction, based on a 1,4-dehydrohalogenation reaction, was extended in terms of substrates and leaving groups allowing the assembly of tetrahydroquinolines in two synthetic steps. Intramolecular cleavage of a thiocarbamate using triphenylphosphine and tetrachloromethane (Appel conditions) to give chloromethyl phenylisocyanate has been presented for the first time. The synthetic feasibility of this process was demonstrated in the first total syntheses of the alkaloids rac-Angustureine and 1-methyl-2-propyltetrahydroquinoline. 相似文献
10.