全文获取类型
收费全文 | 205925篇 |
免费 | 2074篇 |
国内免费 | 519篇 |
专业分类
化学 | 113102篇 |
晶体学 | 3674篇 |
力学 | 8132篇 |
综合类 | 11篇 |
数学 | 19553篇 |
物理学 | 64046篇 |
出版年
2020年 | 1851篇 |
2019年 | 2038篇 |
2018年 | 2389篇 |
2017年 | 2456篇 |
2016年 | 3664篇 |
2015年 | 2331篇 |
2014年 | 3695篇 |
2013年 | 9341篇 |
2012年 | 6721篇 |
2011年 | 8252篇 |
2010年 | 5832篇 |
2009年 | 5779篇 |
2008年 | 7273篇 |
2007年 | 7197篇 |
2006年 | 6803篇 |
2005年 | 6156篇 |
2004年 | 5593篇 |
2003年 | 5170篇 |
2002年 | 4929篇 |
2001年 | 6201篇 |
2000年 | 4667篇 |
1999年 | 3565篇 |
1998年 | 2767篇 |
1997年 | 2724篇 |
1996年 | 2628篇 |
1995年 | 2475篇 |
1994年 | 2353篇 |
1993年 | 2192篇 |
1992年 | 2851篇 |
1991年 | 2766篇 |
1990年 | 2688篇 |
1989年 | 2703篇 |
1988年 | 2737篇 |
1987年 | 2744篇 |
1986年 | 2614篇 |
1985年 | 3335篇 |
1984年 | 3334篇 |
1983年 | 2620篇 |
1982年 | 2729篇 |
1981年 | 2772篇 |
1980年 | 2558篇 |
1979年 | 2893篇 |
1978年 | 2884篇 |
1977年 | 2998篇 |
1976年 | 2832篇 |
1975年 | 2559篇 |
1974年 | 2516篇 |
1973年 | 2475篇 |
1972年 | 1706篇 |
1968年 | 1713篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
K. N. Ponomaryov 《Algebra and Logic》1998,37(6):380-390
The structure of scalar fields for a directly indecomposable finite-dimensional algebra treated as a ring is studied. Scalar
fields are assumed similar if their action on a ring is identical modulo an annihilator. The criterion for a class of maximal
scalar fields to be unique under a similitude relation is established.
Supported by RFFR grant No. 96-01-01675, and by RF State Committee of Higher Education.
Translated fromAlgebra i Logika, Vol. 37, No. 6, pp. 667–686, November–December, 1998. 相似文献
202.
V. T. Astrelin A. V. Burdakov V. S. Koidan K. I. Mekler P. I. Mel’nikov V. V. Postupaev M. A. Shcheglov 《Journal of Experimental and Theoretical Physics》1998,86(3):489-500
This paper presents the results of experiments on two-stage heating of a dense plasma by a relativistic electron beam in the
GOL-3 facility. A dense plasma with a length of about a meter and a hydrogen density up to 1017 cm−3 was created in the main plasma, whose density was 1015 cm−3. In the process of interacting with the plasma, the electron beam (1 MeV, 40 kA, 4 μs) imparts its energy to the electrons of the main plasma through collective effects. The heated electrons, as they disperse
along the magnetic field lines, in turn reach the region of dense plasma and impart their energy to it by pairwise collisions.
Estimates based on experimental data are given for the parameters of the flux of hot plasma electrons, the energy released
in the dense plasma, and the energy balance of the beam-plasma system. The paper discusses the dynamics of the plasma, which
is inhomogeneous in density and temperature, including the appearance of pressure waves.
Zh. éksp. Teor. Fiz. 113, 897–917 (March 1998) 相似文献
203.
The problems of choosing the optimal mathematical model for a prescribed range of parameters of a pulsed action are discussed.
A preliminary analysis performed by similarity and dimensional-analysis methods using interpolation equations of state of
the matter shows that the complete system of equations of gasdynamics can be simplified by dropping individual terms which
are not important in a given parameter range. The results of an analysis are presented in the form of nomograms, which also
make it possible to identify the class of fast and energy-intensive gasdynamic processes more accurately than at an intuitive
level.
Zh. Tekh. Fiz. 68, 44–47 (May 1998) 相似文献
204.
The solvent extraction of cobalt(II), nickel(II) and copper(II) using 2,4-pent-dione (Hacac) and 4-phenyl-2, 4-but-dione (Hbzac)
is carried out by varying the reagent concentration and pH of the aqueous phase. Each of these metals is quantitatively separated
(≈ 98%) from their binary mixtures with monovalent (Ag), divalent (Mn, Zn, Cd, Hg, Mg, Sn, Pb) and trivalent (Cr, Fe) metals.
The extraction constants are calculated from the metal distribution data using linear regression analysis. The extracted species
is MA2 in each case. A most significant result is separation of copper(II) from iron(III) which otherwise interferes when extracted
from the acidic medium. 相似文献
205.
The structure of the lattice of processes of a finite digraph with entries is investigated. Necessary and sufficient conditions
for the isomorphism of a given lattice to the lattice of processes of a certain digraph are obtained. Bibliography: 5 titles.
Translated by K. V. Shakhbazyan.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 202, 1992, pp. 135–153. 相似文献
206.
207.
208.
H.G.C. Human N.P. Ferreira C.J. Rademeyer P.K. Faure 《Spectrochimica Acta Part B: Atomic Spectroscopy》1982,37(7):593-602
A method and computer program were developed for calculating the temperature of any part of a graphite furnace tube at any instant of time after onset of the heating cycle. Results for tubes of the Massman design show large differences in spatial temperature distributions during and at the end of the heating cycle when equilibrium is reached. When constant current is applied to contoured tubes, greater heating rates at the tube centres are obtained than with standard tubes. 相似文献
209.
The ideas developed by Gell-Mann and Okubo in studying violation of unitary symmetry are used to describe violation of isototic invariance in strong interactions. The present consideration is performed for the example of the mass spectrum of the octet formed by baryons of spin-parity 1/2+: only for this family are the widths of its particles much less than the scale of the effects being investigated, their masses being known from experiments to a fairly high precision. The Gell-Mann-Okubo formula is generalized in such a way that relations both for the splitting between the isomultiplets of the octet and for the mass splitting within these isomultiplets follow from the new formula. Moreover, a relation between masses that describes their electromagnetic splitting and which coincides in form with the Coleman-Glashow relation also follows from this formula. The relations obtained for the masses of the baryons belonging to the octet in question are satisfied to a precision not poorer than 3%. 相似文献
210.
P. Dimopoulos K. Farakos S. Nicolis 《The European Physical Journal C - Particles and Fields》2002,24(2):287-296
We explore the phase diagram of the five-dimensional anisotropic Abelian Higgs model by Monte Carlo simulations. In particular,
we study the transition between the confining phase and the four-dimensional layered Higgs phase. We find that, in a certain
region of the lattice parameter space, this transition can be first order, and that each layer moves into the Higgs phase
independently of the others (decoupling of layers). As the Higgs couplings vary, we find, using mean field techniques, that
this transition may probably become second order.
Received: 21 December 2001 / Published online: 12 April 2002 相似文献