全文获取类型
收费全文 | 1266095篇 |
免费 | 25653篇 |
国内免费 | 7663篇 |
专业分类
化学 | 620843篇 |
晶体学 | 19910篇 |
力学 | 73326篇 |
综合类 | 101篇 |
数学 | 236691篇 |
物理学 | 348540篇 |
出版年
2021年 | 13448篇 |
2020年 | 15854篇 |
2019年 | 15983篇 |
2016年 | 26885篇 |
2015年 | 20454篇 |
2014年 | 30225篇 |
2013年 | 74009篇 |
2012年 | 33879篇 |
2011年 | 27622篇 |
2010年 | 34581篇 |
2009年 | 37629篇 |
2008年 | 28124篇 |
2007年 | 22878篇 |
2006年 | 31383篇 |
2005年 | 22681篇 |
2004年 | 25324篇 |
2003年 | 24730篇 |
2002年 | 26326篇 |
2001年 | 24066篇 |
2000年 | 22105篇 |
1999年 | 21266篇 |
1998年 | 20528篇 |
1997年 | 20589篇 |
1996年 | 20870篇 |
1995年 | 19012篇 |
1994年 | 18428篇 |
1993年 | 17956篇 |
1992年 | 17460篇 |
1991年 | 17804篇 |
1990年 | 17034篇 |
1989年 | 17143篇 |
1988年 | 16686篇 |
1987年 | 16735篇 |
1986年 | 15615篇 |
1985年 | 22090篇 |
1984年 | 23482篇 |
1983年 | 19749篇 |
1982年 | 21500篇 |
1981年 | 20752篇 |
1980年 | 20081篇 |
1979年 | 20084篇 |
1978年 | 21509篇 |
1977年 | 21058篇 |
1976年 | 20718篇 |
1975年 | 19387篇 |
1974年 | 19011篇 |
1973年 | 19491篇 |
1972年 | 14014篇 |
1968年 | 11891篇 |
1967年 | 12269篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
M. M. Moustafa 《Journal of Thermal Analysis and Calorimetry》1997,50(3):463-471
The oxime and Schiff's base of N-furoylphenylhydroxylamine form complexes with Co2+, Cu2+, Zn2+ and Fe3+. These complexes were studied by means of the UV — Vis. spectra of nujol mulls, electron spin resonance (ESR) spectra and magnetic susceptibility to determine their stereochemistry. The complexes were characterized via elemental analyses, molar conductivities and thermogravimetric analyses. Organic reagents were used for the gravimetric determination of Co2+, Cu2+ and Fe3+ through the precipitation of their complexes. The compounds were also used for separation of a binary mixture of Cu2+ and Cu2+. Interferences were studied. 相似文献
75.
76.
S. A. Gurevich T. A. Zaraiskaya S. G. Konnikov V. M. Mikushkin S. Yu. Nikonov A. A. Sitnikova S. E. Sysoev V. V. Khorenko V. V. Shnitov Yu. S. Gordeev 《Physics of the Solid State》1997,39(10):1691-1695
The concentration and chemical state of copper in the subsurface region of Cu/SiO2 composite films obtained by simultaneous magnetron sputtering from two sources (Cu and SiO2) are determined by x-ray photoelectron spectroscopy (XPS). It is established that copper in the as-grown film is primarily in the form of unoxidized atoms dispersed in a SiO2 matrix. Annealing of the film results in practically no oxidation, but about 70% of the copper atoms condense into metallic clusters with sizes below 10 Å in the subsurface region and about 50 Å in the bulk of the film. The changes in the binding energy of core electrons, and especially in the energies of Auger electrons, are so large in this situation that photoelectron and Auger spectroscopy are efficient methods for monitoring the chemical state of this composite material. 相似文献
77.
Ya. V. Fattakhov M. F. Galyautdinov T. N. L’vova I. B. Khaibullin 《Technical Physics》1997,42(12):1457-1459
The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface
upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures
is discussed.
Zh. Tekh. Fiz. 67, 97–99 (December 1997) 相似文献
78.
A converging perturbation series that can be summed analytically has been obtained for intersubband transitions of electrons
coherently tunneling through the middle of a dimensionally quantized level in an asymmetric double-barrier structure in a
high-frequency terahertz electric field. The possibility of a substantial increase in tunneling current accompanied by either
absorption or emission of a photon has been demonstrated. The quantum efficiency of radiative transitions between dimensionally
quantized levels can be up to 66%.
Zh. éksp. Teor. Fiz. 112, 237–245 (July 1997) 相似文献
79.
The changes in the magnetization of yttrium iron garnet (YIG) when irradiated by a pulsed neodymium laser beam with wavelength
λ=1.06 μm are investigated. Measurements are performed in the temperature range from 100 K to 600 K in various external magnetic
fields. YIG single crystals grown along the crystallographic (100), (110), and (111) directions are chosen so that the external
anisotropy of the indicated processes can be determined. Characteristic temperature intervals dominated by different mechanisms
of variation of the magnetization under the influence of a laser pulse are discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 1263–1266 (July 1997) 相似文献
80.
L. K. Aminov I. N. Kurkin D. A. Lukoyanov K. P. Chernov 《Physics of the Solid State》1997,39(8):1184-1186
Results are reported for measurements of the spin-lattice relaxation times of E′1 centers in quartz glass, produced by neutron irradiation, with the measurements made at two frequencies 9.25 and 24.0 GHz
over a wide temperature interval 1.5–300 K. The experimental data are interpreted on the basis of interaction mechanisms of
the spins with two-level systems with excitation energies ∼6, ∼26, and ∼420 cm−1. A small modification of the existing theory allows us to explain a number of features of the observed temperature and frequency
dependence of the relaxation rate. The results are compared with the data available in the literature on spin-lattice relaxation
of irradiation centers in crystalline quartz and quartz glass.
Fiz. Tverd. Tela (St. Petersburg) 39, 1335–1337 (August 1997) 相似文献