全文获取类型
收费全文 | 389255篇 |
免费 | 4192篇 |
国内免费 | 1869篇 |
专业分类
化学 | 206586篇 |
晶体学 | 5919篇 |
力学 | 17119篇 |
综合类 | 64篇 |
数学 | 45060篇 |
物理学 | 120568篇 |
出版年
2020年 | 3247篇 |
2019年 | 3593篇 |
2018年 | 4725篇 |
2017年 | 4645篇 |
2016年 | 6774篇 |
2015年 | 4349篇 |
2014年 | 6600篇 |
2013年 | 16630篇 |
2012年 | 13610篇 |
2011年 | 16464篇 |
2010年 | 11562篇 |
2009年 | 11325篇 |
2008年 | 15225篇 |
2007年 | 15483篇 |
2006年 | 14653篇 |
2005年 | 13193篇 |
2004年 | 12023篇 |
2003年 | 10661篇 |
2002年 | 10431篇 |
2001年 | 11690篇 |
2000年 | 9006篇 |
1999年 | 6796篇 |
1998年 | 5574篇 |
1997年 | 5533篇 |
1996年 | 5320篇 |
1995年 | 4830篇 |
1994年 | 4788篇 |
1993年 | 4559篇 |
1992年 | 5107篇 |
1991年 | 5108篇 |
1990年 | 4839篇 |
1989年 | 4602篇 |
1988年 | 4590篇 |
1987年 | 4547篇 |
1986年 | 4375篇 |
1985年 | 5767篇 |
1984年 | 6057篇 |
1983年 | 5022篇 |
1982年 | 5387篇 |
1981年 | 5144篇 |
1980年 | 4856篇 |
1979年 | 5083篇 |
1978年 | 5417篇 |
1977年 | 5417篇 |
1976年 | 5442篇 |
1975年 | 5034篇 |
1974年 | 5120篇 |
1973年 | 5308篇 |
1972年 | 3804篇 |
1971年 | 3003篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
982.
983.
Crystals of 1,6-8, 13-bis-oxido-[14]-annulene are monoclinic, a = 9,29, b = 9,74, c = 11,46 Å, β = 90,0°, space group P 21/c, with 4 molecules in the unit cell. The structure has been solved by direct methods and refined by full-matrix least-squares analysis of three-dimensional intensity data. The cis-configuration of the two oxygen bridges is confirmed, and the observed molecular parameters are in full accord with the aromatic properties of the molecule. 相似文献
984.
L. Acker 《Fresenius' Journal of Analytical Chemistry》1960,176(2):143
Ohne Zusammenfassung 相似文献
985.
N. K. Gusarova N. A. Chernysheva M. Ya. Khil'ko S. V. Yas'ko L. M. Sinegovskaya N. N. Chipanina N. A. Korchevin B. A. Trofimov 《Russian Journal of General Chemistry》2005,75(8):1247-1250
Selective monoaddition of carbonodithioate anions to divinyl sulfoxide gives rise to O-alkyl S-[2-(vinylsulfinyl)ethyl] carbonodithioates [ROC(S)SK, R = Et, Bu; 42–50°C, 6 h, NaHCO3, aqueous benzene]. 相似文献
986.
A. V. Kashevskii M. A. Mamalyga T. L. Petrova A. Yu. Safronov V. N. Kizhnyaev 《Russian Journal of Applied Chemistry》2007,80(2):316-321
Copolymers of 1-vinyl-1,2,4-triazole and 5-vinyltetrazole with 1,1,5-trihydrooctafluoropentyl methacrylate and 1,1,7-trihydrododecafluoroheptyl methacrylate were prepared under the conditions of radical initiation. These copolymers were used for modification of the surface of a glassy carbon electrode, and the effect of the modification on the electrochemical behavior of the electrode in anodic oxidation of dopamine and NO was studied. The possibility of enhancing the selectivity of the electrochemical sensor for monitoring NO in biological media was demonstrated. 相似文献
987.
N. S. Shaglaeva O. V. Lebedeva Yu. N. Pozhidaev R. G. Sultangareev S. S. Bochkareva L. A. Es’kova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(3):335-338
Hybrid organoinorganic composites insoluble in water and organic solvents were prepared by the hydrolysis of tetraethoxysilane in the presence of poly-1-vinylpyrazole, poly-1-vinylimidazole, and poly-4-vinylpyridine. The composition of the composites was determined by the nature of the polymeric nitrogen base and hydrolysis conditions. The composites synthesized showed high sorption activity in the extraction of the [PdCl4]2?, [PtCl6]2?, and [AuCl4]? ions from hydrochloric acid solutions. 相似文献
988.
Devyatkina T. I. Gun'ko Yu. L. Mikhalenko M. G. 《Russian Journal of Applied Chemistry》2001,74(7):1122-1125
The influence exerted by addition of -hydroxynaphthoic acid and combined additive Hg + Pb + -hydroxynaphthoic acid on the corrosion and self-discharge of a porous zinc electrode in alkali solution was studied. 相似文献
989.
Serber Z Ledwidge R Miller SM Dötsch V 《Journal of the American Chemical Society》2001,123(37):8895-8901
Our recently developed in-cell NMR procedure now enables one to observe protein conformations inside living cells. Optimization of the technique demonstrates that distinguishing the signals produced by a single protein species depends critically on protein overexpression levels and the correlation time in the cytoplasm. Less relevant is the selective incorporation of (15)N. Poorly expressed proteins, insoluble proteins, and proteins that cannot tumble freely due to associations within the cell cannot yet be observed. We show in-cell NMR spectra of bacterial NmerA and human calmodulin and discuss limitations of the technique as well as prospects for future applications. 相似文献
990.
Yaroshenko A. P. Savos'kin M. V. Magazinskii A. N. Galushko L. Ya. 《Russian Journal of Applied Chemistry》2004,77(2):192-195
The influence exerted by the particle size and the distribution of sol impurities in the initial graphite, and also by pyrite additives, on the properties of residual graphite hydrosulfates synthesized by oxidation in the CrO3-H2SO4 system was studied. 相似文献