全文获取类型
收费全文 | 181509篇 |
免费 | 1894篇 |
国内免费 | 588篇 |
专业分类
化学 | 95425篇 |
晶体学 | 3100篇 |
力学 | 7288篇 |
综合类 | 3篇 |
数学 | 21087篇 |
物理学 | 57088篇 |
出版年
2020年 | 1604篇 |
2019年 | 1717篇 |
2018年 | 2084篇 |
2017年 | 2149篇 |
2016年 | 3451篇 |
2015年 | 2103篇 |
2014年 | 3367篇 |
2013年 | 8160篇 |
2012年 | 6255篇 |
2011年 | 7468篇 |
2010年 | 5380篇 |
2009年 | 5321篇 |
2008年 | 7075篇 |
2007年 | 6952篇 |
2006年 | 6602篇 |
2005年 | 6001篇 |
2004年 | 5488篇 |
2003年 | 4899篇 |
2002年 | 4814篇 |
2001年 | 5393篇 |
2000年 | 4052篇 |
1999年 | 3125篇 |
1998年 | 2646篇 |
1997年 | 2532篇 |
1996年 | 2396篇 |
1995年 | 2254篇 |
1994年 | 2250篇 |
1993年 | 2135篇 |
1992年 | 2422篇 |
1991年 | 2360篇 |
1990年 | 2288篇 |
1989年 | 2199篇 |
1988年 | 2190篇 |
1987年 | 2188篇 |
1986年 | 2083篇 |
1985年 | 2739篇 |
1984年 | 2784篇 |
1983年 | 2454篇 |
1982年 | 2606篇 |
1981年 | 2401篇 |
1980年 | 2370篇 |
1979年 | 2525篇 |
1978年 | 2554篇 |
1977年 | 2475篇 |
1976年 | 2533篇 |
1975年 | 2424篇 |
1974年 | 2385篇 |
1973年 | 2566篇 |
1972年 | 1666篇 |
1971年 | 1375篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
101.
The dependence of the strangeness saturation factor on the system size, centrality and energy is studied in relativistic heavy-ion collisions. 相似文献
102.
Spatial parameters of the X-ray radiation produced by a high-voltage nanosecond discharge evolving in air under atmospheric
pressure in the rod (cathode)-plane electrode system with a 10-cm electrode spacing are studied experimentally. A ∼170-ns
voltage pulse with an amplitude of ∼200 kV and 10-ns rise time is applied to the cathode. The photoelectronic method is used
to study, under the same conditions, the integrated (over the gap) characteristics of the radiation, in particular, the duration
of its generation. It is found that, when the size of the X-ray source is not smaller than that of the discharge region of
diffusive luminescence, radiation from the cathode region of the gap is primarily observed (i.e., from the region where the
electric field distribution is sharply inhomogeneous). The X-ray generation is usually observed after the bridging of the
discharge gap, the X-ray pulse having a rise time of ∼3 ns, a duration of ∼10 ns, and an effective radiation energy of ∼6
keV. 相似文献
103.
O. Yu. Borkovskaya N. L. Dmitruk I. B. Ermolovich R. V. Konakova V. V. Milenin 《Technical Physics》2004,49(3):325-329
The properties of nonrectifying AuGe/GaAs (Al0.4Ga0.6As) contacts exposed to heat treatment, 60Co γ radiation, and γ radiation combined with the application of an electrical bias are studied. A correlation between the
type of interfacial interaction in the contacts and their resistance is found. Results obtained are explained in terms of
a diffusion model with a movable boundary of the metal layer. 相似文献
104.
105.
Experimental studies of the scattering of a monochromatic sound signal by a rough sea surface are carried out. The signal is produced by a point source in a shallow-water basin. The measurements are performed with the use of horizontal and vertical linear receiving arrays. The experimental data are compared with the estimates obtained on the basis of the model developed by the authors for resonant sound scattering by surface roughness. A satisfactory agreement between the experiments and the calculations is achieved. It is shown that the scattered signal is formed within small surface areas, whose sizes have the same order of magnitude as the first Fresnel zone with respect to the source and the receiving system. 相似文献
106.
A. B. Maizel’ 《Acoustical Physics》2004,50(6):717-720
Using the theory of spheroidal wave functions, the total acoustic impedance is determined for a prolate spheroid performing transverse translational and rotational oscillatory movements. Expressions for the radiation resistance, the added mass, and the added moment of inertia are derived. It is shown that, in the lowfrequency approximation, this mass and moment of inertia reach limiting values identical to hydrodynamic ones. The components of the total acoustic impedance are calculated for spheroids of different relative thicknesses at an arbitrary frequency. 相似文献
107.
Yu. B. Bolkhovityanov S. Ts. Krivoshchapov A. I. Nikiforov B. Z. Ol’shanetskii O. P. Pchelyakov L. V. Sokolov S. A. Teys 《Physics of the Solid State》2004,46(1):64-66
Different techniques for the fabrication of structures containing ensembles of ultrasmall germanium nanoclusters distributed with a high density over the substrate surface are discussed. How to control the morphology and ordering of these ensembles is also discussed. 相似文献
108.
B. P. Sorokin D. A. Glushkov L. N. Bezmaternykh V. L. Temerov I. A. Gudim K. S. Aleksandrov 《Physics of the Solid State》2004,46(3):458-461
Single crystals of lead gallium germanate Pb3Ga2Ge4O14 are grown from their own solution melts. The propagation of bulk acoustic waves is investigated, and the elastic, piezoelectric, and dielectric constants are calculated. The temperature dependences of the dielectric constants of this compound are analyzed. 相似文献
109.
E. A. Ekimov E. L. Gromnitskaya D. A. Mazalov A. F. Pal’ V. V. Pichugin S. Gierlotka B. Palosz J. A. Kozubowski 《Physics of the Solid State》2004,46(4):755-757
Superhard nanodiamond-SiC ceramics are prepared by infiltrating liquid Si into porous nanodiamond compacts under pressure.
Synthesized samples are 2.2 mm thick and 3–4 mm in diameter. The effect of particle size of dynamically synthesized nanodiamond
powders on silicon infiltration and SiC phase formation is studied. It is established that silicon does not penetrate into
the pores of nanodiamond powders if the original particle size is smaller than 0.5–1.0 μm. The critical pore size for infiltration
is 100–200 nm. A study of the microstructure of the samples showed the presence of the nanometer-and submicron-scale SiC phase.
The ultrasound velocities are measured in the prepared compacts, and the elastic moduli are calculated.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 4, 2004, pp. 734–736.
Original Russian Text Copyright ? 2004 by Ekimov, Gromnitskaya, Mazalov, Pal’, Pichugin, Gierlotka, Palosz, Kozubowski. 相似文献
110.
Oksengendler B. L. Karimov M. Yunusov M. C. Karakhodzhaev A. K. 《Russian Physics Journal》2004,47(7):790-791
Russian Physics Journal - 相似文献