全文获取类型
收费全文 | 440955篇 |
免费 | 4969篇 |
国内免费 | 1264篇 |
专业分类
化学 | 237238篇 |
晶体学 | 6519篇 |
力学 | 18878篇 |
综合类 | 13篇 |
数学 | 50728篇 |
物理学 | 133812篇 |
出版年
2021年 | 3813篇 |
2020年 | 4249篇 |
2019年 | 4579篇 |
2018年 | 5901篇 |
2017年 | 5790篇 |
2016年 | 8960篇 |
2015年 | 5656篇 |
2014年 | 8648篇 |
2013年 | 20404篇 |
2012年 | 15927篇 |
2011年 | 19572篇 |
2010年 | 13661篇 |
2009年 | 13501篇 |
2008年 | 17940篇 |
2007年 | 17867篇 |
2006年 | 16595篇 |
2005年 | 14842篇 |
2004年 | 13783篇 |
2003年 | 12132篇 |
2002年 | 11942篇 |
2001年 | 13500篇 |
2000年 | 10128篇 |
1999年 | 7955篇 |
1998年 | 6612篇 |
1997年 | 6367篇 |
1996年 | 6149篇 |
1995年 | 5524篇 |
1994年 | 5450篇 |
1993年 | 5285篇 |
1992年 | 5880篇 |
1991年 | 5969篇 |
1990年 | 5731篇 |
1989年 | 5510篇 |
1988年 | 5527篇 |
1987年 | 5402篇 |
1986年 | 5119篇 |
1985年 | 6624篇 |
1984年 | 6742篇 |
1983年 | 5335篇 |
1982年 | 5444篇 |
1981年 | 5418篇 |
1980年 | 4996篇 |
1979年 | 5390篇 |
1978年 | 5529篇 |
1977年 | 5407篇 |
1976年 | 5364篇 |
1975年 | 4933篇 |
1974年 | 4900篇 |
1973年 | 4892篇 |
1972年 | 3460篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A. I. Saidkhodzhaev V. M. Malikov M. G. Pimenov S. Melibaev 《Chemistry of Natural Compounds》1993,29(2):253-254
Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Botanical Garden of Moscow State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 301–303, March–April, 1993. 相似文献
992.
Radionuclide X-ray fluorescence analysis was used for the determination of Cr, Fe, Cu, Zn and Pb in industrial wastewaters (from surface treatment of metals and glasses) after precipitation of determined elements by 8-hydroxyquinoline. 相似文献
993.
T. Sato F. Ambe K. Endo M. Katada H. Sano 《Journal of Radioanalytical and Nuclear Chemistry》1995,190(2):257-261
The crystal structures of oxo-centered trineclear cobalt-iron chloroacetate complex [CoIIFe
2
III
O(CH2ClCO2)6(H2O)3]·3H2O (1) was compared with that of previously reported trinuclear iron complex [FeIIFe
2
III
O(CH2ClCO2)6(H2O)3]·3H2O (2) which has an isomorphous structure to 1. Compound 1 crystallizes in space group P21/n with Z=4 in a unit cell of a=14.826 (4) Å, b=4.536 (8) Å, c=14.000 (4) Å, =100.32 (2)0 and V=2968 (11) Å3. The structure was refined to R=0.75 and Rw=0.82. The coordination geometries of the three iron atoms are observed equivalent in 1 indicating a static disorder of the position among cobalt and iron atoms. Two distinct FeIII doublets observed in Mössbauer spectra of 1 become an indistinguishable broad doublet by dehydration of crystal water. On the other hand, no significant line-broadening is observed after the dehydration in complex 2. The results indicate that the dehydration in 2 induces a local environmental change reordering of an electronic configuration around iron atoms, whereas the remaining disordering is reflected in Mössbauer spectrum after the dehydration in 1. 相似文献
994.
995.
996.
997.
L. S. Andreeva A. A. Andrianov V. E. Bel'skii M. F. Vavilova É. A. Gurylev K. V. Nikonorov 《Russian Chemical Bulletin》1971,20(10):2219-2221
Conclusions The hydrolysis of chloroacetophos in water includes the parallel cleavage of acetic acid, hydrochloric acid and methanol. The ratio of the products, formed in the parallel steps, was determined, and we also determined the total rate constant for the hydrolysis of chloroacetophos.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2336–2338, October, 1971. 相似文献
998.
999.
A. N. Dmitrievskii A. A. Pribylov N. A. Skibitskaya L. A. Zekel’ A. P. Kubyshkin M. Ya. Shpirt 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(7):1099-1104
Isotherms of sorption of butane, propane, ethane, methane, and carbon dioxide on an asphaltene sample of known elemental composition were measured. The effect of the pressure and temperature on the shape the sorption isotherms for all the adsorption systems studied was examined. The values of the initial heat of sorption were determined and compared to the energies of interaction of the molecules with asphaltene. The results obtained suggest that asphaltene is a swellable amorphous sorbent. 相似文献
1000.