全文获取类型
收费全文 | 1246篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
化学 | 627篇 |
晶体学 | 39篇 |
力学 | 93篇 |
综合类 | 1篇 |
数学 | 173篇 |
物理学 | 321篇 |
出版年
2021年 | 10篇 |
2019年 | 14篇 |
2018年 | 23篇 |
2017年 | 33篇 |
2016年 | 47篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 51篇 |
2012年 | 53篇 |
2011年 | 65篇 |
2010年 | 55篇 |
2009年 | 45篇 |
2008年 | 50篇 |
2007年 | 27篇 |
2006年 | 35篇 |
2005年 | 39篇 |
2004年 | 39篇 |
2003年 | 37篇 |
2002年 | 31篇 |
2001年 | 35篇 |
2000年 | 29篇 |
1999年 | 12篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 23篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 25篇 |
1986年 | 21篇 |
1985年 | 10篇 |
1984年 | 17篇 |
1983年 | 19篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 16篇 |
1979年 | 14篇 |
1978年 | 23篇 |
1977年 | 15篇 |
1976年 | 19篇 |
1975年 | 10篇 |
1974年 | 16篇 |
1973年 | 17篇 |
1971年 | 12篇 |
1970年 | 11篇 |
1969年 | 12篇 |
1967年 | 11篇 |
1966年 | 10篇 |
排序方式: 共有1254条查询结果,搜索用时 15 毫秒
141.
E. N. Aleksandrov N. M. Kuznetsov V. V. Lunin D. A. Lemenovskii A. G. Merzhanov A. L. Petrov V. Yu. Lidzhi-Goryaev 《Russian Journal of Physical Chemistry B, Focus on Physics》2013,7(7):802-809
Thermodynamic aspects of an innovative binary-mixture (BM) technology for increasing the productivity of oil-bearing beds that provides a substantial reduction of oil-well watering (compared to conventional steam heating) are discussed. Inorganic and organic ammonium nitrates (NH4NO3 and HOCH2NH 3 + NO 3 - respectively) are compared qua heat-producing components of a BM that also contains sodium nitrite as an initiator of nitrate decomposition. Effects of temperature and pressure on the product distribution and heat production in ethanolammonium nitrate decomposition are evaluated. Calculations of parameters in a near-well space taking into account the heat capacity of the surrounding rock layer show that temperature and pressure can exceed their critical values for both water and main oil fractions. As a result, conditions for an intense upward flow of water—oil fluid in an artificial gas-lift regime arise. 相似文献
142.
143.
N. L. Aleksandrov A. V. Chirkov G. G. Denisov S. V. Kuzikov 《International Journal of Infrared and Millimeter Waves》1997,18(6):1323-1334
A method of mode content analysis in oversized waveguides basing on intensity measurements in a few cross sections is suggested.
The method is based on iterative synthesis of phase fronts of the radiation measured in a few cross sections of an oversized
waveguide. The phase reconstruction makes it possible to calculate field distribution as well as the mode content at any place
of the waveguide. The method was tested in experiments with circular and rectangular waveguides with impedance corrugation
of the walls [8]. 相似文献
144.
E. I. Tsyganova I. I. Didenkulova V. M. Shekunova Yu. A. Aleksandrov 《Russian Journal of General Chemistry》2005,75(10):1599-1602
New catalytic systems for oxidation of CO to CO2 were developed. These systems are based on composite Mn, Mn-Ni, and Mn-Cu coatings and are prepared by gas-phase thermolysis of metal β-diketonates on a ceramic foam support. The relative activity of the new catalytic systems was examined. The kinetic and activation parameters of the oxidation of CO on these catalysts were determined. 相似文献
145.
I. P. Aleksandrov A. F. Bovina O. A. Ageev A. A. Sukhovskii 《Physics of the Solid State》1997,39(6):991-994
An incommensurate phase is observed in a Cs3Bi2I9 crystal, which belongs to the family of layered A3B2X9 structures. Data from 127I NQR and x-ray powder diffraction patterns show that the second-order normal phase—incommensurate phase transition at T
i=220 K is accompanied by a P63/mmc↔P21/m symmetry change and takes place at the center of the Brillouin zone. The nature of the instability leading to the appearance
of this little-studied form of incommensurability is discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 1105–1108 (June 1997) 相似文献
146.
Valentine P Ananikov Michael A Kabeshov Irina P Beletskaya Grigory G Aleksandrov 《Journal of organometallic chemistry》2003,687(2):451-461
The mechanistic study of palladium catalyzed S-S and Se-Se bonds addition to alkynes revealed the involvement of dinuclear transition metal complexes in the catalytic cycle. Coordination of alkyne to dinuclear transition metal complex was found to be the rate determining step of the reaction. An unusual phosphine ligand effect increasing the yield of addition reaction was found in the studied system. A new synthetic procedure was developed to perform the catalytic reaction using easily available Pd(II) complex. The scope of the reaction and the reactivity of S-S and Se-Se bonds toward alkynes were investigated. The X-ray structure of the product of S-S bond addition reaction showed favorable geometry for the possible application as a chelate ligand. 相似文献
147.
E. I. Tsyganova I. I. Didenkulova V. M. Shekunova V. I. Faerman Yu. A. Aleksandrov 《Russian Journal of General Chemistry》2004,74(11):1646-1650
The kinetic features of thermal decomposition of cobalt acetylacetonate in a vacuum were elucidated, and the volatile thermolysis products were identified. The homogeneous-heterogeneous character of the process was shown. Catalysts for the oxidation of CO to CO2 were developed on the basis of cobalt acetylacetonate decomposition products and synthetic cellular ceramics, and the kinetic and activation parameters of the oxidation were determined.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1770–1774.Original Russian Text Copyright © 2004 by Tsyganova, Didenkulova, Shekunova, Faerman, Aleksandrov.This revised version was published online in April 2005 with a corrected cover date. 相似文献
148.
The formation of porous silicon is investigated by the Monte Carlo method in a model that takes account of the nonuniformity
of the charge distribution over the silicon-electrolyte interface, hole diffusion, generation, and recombination processes,
and size quantization. The structures obtained in a computer simulation for various doping levels of the crystalline substrate,
temperatures, HF concentrations, and anode current densities are presented. Analysis of nanoporous structures shows that the
porosity depends on the depth and reveals the presence of a fractal dimensionality on scales of less than 10 nm.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 9, 685–690 (10 May 1997) 相似文献
149.
The effect of photoinduced emission of alkali atoms from the paraffin coating of a cell on the spin relaxation time of the atoms was studied experimentally. No effect was detected. It was additionally found that long irradiation of the cell surface by light with a power density of about 1 mW/cm2 does not cause any degradation of the coating in spite of almost complete removal of the atoms from the coating due to their photostimulated diffusion in the layer and photodesorption. After the irradiation is complete, the surface contacting with the alkali vapor is again saturated with the alkali atoms with a time constant of about 1 h. 相似文献
150.
V. Burjan J. Cejpek J. Fojtu V. Kroha D. V. Aleksandrov B. G. Novatskii D. N. Stepanov 《Zeitschrift für Physik A Hadrons and Nuclei》1996,354(1):163-167
The differential cross sections of elastic and inelastic scattering of3He ions on the14C nucleus have been measured at an energy of 37.9 MeV. By fitting the shape of the measured angular distribution of the elastic scattering the parameters of the optical model have been found. These parameters have been used for the standard DWBA calculations of angular distributions corresponding to excitations of the14C levels 6.73(3?), 7.01(2+) and 8.32(2+) MeV and for coupled channels calculations of the level 8.32(2+) MeV. The vibration parametersβ L of the14C nucleus have been deduced. 相似文献