全文获取类型
收费全文 | 436060篇 |
免费 | 4852篇 |
国内免费 | 1230篇 |
专业分类
化学 | 233770篇 |
晶体学 | 6489篇 |
力学 | 18764篇 |
综合类 | 13篇 |
数学 | 49938篇 |
物理学 | 133168篇 |
出版年
2021年 | 3770篇 |
2020年 | 4186篇 |
2019年 | 4518篇 |
2018年 | 5855篇 |
2017年 | 5747篇 |
2016年 | 8833篇 |
2015年 | 5561篇 |
2014年 | 8542篇 |
2013年 | 20186篇 |
2012年 | 15649篇 |
2011年 | 19262篇 |
2010年 | 13497篇 |
2009年 | 13350篇 |
2008年 | 17647篇 |
2007年 | 17541篇 |
2006年 | 16252篇 |
2005年 | 14550篇 |
2004年 | 13525篇 |
2003年 | 11892篇 |
2002年 | 11728篇 |
2001年 | 13429篇 |
2000年 | 10085篇 |
1999年 | 7916篇 |
1998年 | 6569篇 |
1997年 | 6314篇 |
1996年 | 6081篇 |
1995年 | 5470篇 |
1994年 | 5392篇 |
1993年 | 5197篇 |
1992年 | 5828篇 |
1991年 | 5924篇 |
1990年 | 5665篇 |
1989年 | 5472篇 |
1988年 | 5493篇 |
1987年 | 5374篇 |
1986年 | 5091篇 |
1985年 | 6560篇 |
1984年 | 6694篇 |
1983年 | 5301篇 |
1982年 | 5388篇 |
1981年 | 5367篇 |
1980年 | 4955篇 |
1979年 | 5352篇 |
1978年 | 5491篇 |
1977年 | 5385篇 |
1976年 | 5328篇 |
1975年 | 4914篇 |
1974年 | 4885篇 |
1973年 | 4880篇 |
1972年 | 3455篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
IR and Raman spectra of (NH4)3ZnCl5 have been recorded. The observed spectra have been analysed on the basis of the vibrations of ZnCl
4
2−
and NH
4
+
ions. The appearance of multiple Raman bands indicates the presence of two different types of ammonium ions. The effect of
anisotropic crystalline field over the ZnCl4 and NH4 tetrahedra is also discussed. The assignment of internal modes has been verified by the potential energy distribution calculations. 相似文献
992.
L. S. de C. Oliveira M. T. X. Silva A. Vasquez J. A. H. da Jornada 《Hyperfine Interactions》1991,66(1-4):267-270
An exploratory Mössbauer spectroscopy study of the Fe-C system in the C rich region, prepared by high pressure-high temperature treatment near the graphite-diamond stability line, was made. The results obtained for the different processing conditions give no evidence of Fe intercalation in graphite. The presence of some water in the cell produced hydrated Fe complexes, which can explain the deleterious effect of water or hydrogen in the high pressure diamond synthesis. 相似文献
993.
Eggenhffner R. Masini R. Bellingeri E. Cimberle M. R. Ferdeghini C. Costa G. A. Kaiser E. Signorelli E. 《Il Nuovo Cimento D》1994,16(10):1659-1664
Il Nuovo Cimento D - The formation of Hg-based HTSC materials was investigated through the development of non-conventional techniques. The former was based on a singlestep synthesis at temperatures... 相似文献
994.
Summary An attempt is made to explain the masses of Z and W± bosons by means of a screening mechanism analogous to charge screening in metals. It considers the effect of the electroweak
force on the distribution of negativekinetic-energy neutrinos, which fills the whole universe (neutrino Fermi sea). The large
weak-boson masses appear to be a direct consequence of the vanishing neutrino mass. 相似文献
995.
Translated from Matematicheskie Modeli i Optimizatsiya Vychislitel'nykh Algoritmov, pp. 67–74, 1994. 相似文献
996.
997.
V. A. Donchenko M. V. Kabanov V. T. Kalaida B. I. Kulakov E. V. Ovcharenko I. G. Sokovets 《Russian Physics Journal》1998,41(5):476-484
The problems of determining and investigating the informative parameters of atmospheric electricity are discussed. It is shown
that short-period variations in atmospheric electricity are ecologically significant. An automated system for monitoring atmospheric
electricity and a method of processing the results of measurements are described.
V. D. Kuznetsov Siberian Physicotechnical Institute, Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh
Zavedenii, Fizika, No. 5, pp. 88–98, May, 1998. 相似文献
998.
999.
A.-M. M. Abdel-Rahman 《General Relativity and Gravitation》1997,29(10):1329-1343
Aspects of the modified general relativity theory of Rastall, Al-Rawaf and Taha are discussed in both the radiation- and matter-dominated flat cosmological models. A nucleosynthesis constraint on the theory's free parameter is obtained and the implication for the age of the Universe is discussed. The consistency of the modified matter-dominated model with the neoclassical cosmological tests is demonstrated. 相似文献
1000.