全文获取类型
收费全文 | 405115篇 |
免费 | 3246篇 |
国内免费 | 1344篇 |
专业分类
化学 | 190056篇 |
晶体学 | 6048篇 |
力学 | 23236篇 |
综合类 | 92篇 |
数学 | 58671篇 |
物理学 | 131602篇 |
出版年
2021年 | 4256篇 |
2020年 | 4635篇 |
2019年 | 5509篇 |
2018年 | 7974篇 |
2017年 | 8129篇 |
2016年 | 10303篇 |
2015年 | 5042篇 |
2014年 | 9253篇 |
2013年 | 16910篇 |
2012年 | 13977篇 |
2011年 | 16160篇 |
2010年 | 13535篇 |
2009年 | 13589篇 |
2008年 | 15473篇 |
2007年 | 15156篇 |
2006年 | 13571篇 |
2005年 | 11742篇 |
2004年 | 11207篇 |
2003年 | 10318篇 |
2002年 | 10547篇 |
2001年 | 10660篇 |
2000年 | 8410篇 |
1999年 | 6414篇 |
1998年 | 5927篇 |
1997年 | 5713篇 |
1996年 | 5195篇 |
1995年 | 4588篇 |
1994年 | 4627篇 |
1993年 | 4597篇 |
1992年 | 4674篇 |
1991年 | 5150篇 |
1990年 | 5076篇 |
1989年 | 5098篇 |
1988年 | 4748篇 |
1987年 | 4816篇 |
1986年 | 4502篇 |
1985年 | 5379篇 |
1984年 | 5572篇 |
1983年 | 4743篇 |
1982年 | 4995篇 |
1981年 | 4650篇 |
1980年 | 4298篇 |
1979年 | 4932篇 |
1978年 | 5107篇 |
1977年 | 5300篇 |
1976年 | 5452篇 |
1975年 | 5062篇 |
1974年 | 4894篇 |
1973年 | 5132篇 |
1972年 | 4307篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
A. L. Apanasenko A. V. Kuznichenko Yu. B. Govyadovskii V. G. Yakunin 《Journal of Applied Spectroscopy》1991,54(3):271-276
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 3, pp. 438–444, March, 1991. 相似文献
52.
Yu. K. Voron'ko A. B. Kudryavtsev V. V. Osiko E. V. Sorokin 《Journal of Applied Spectroscopy》1991,55(4):953-957
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 535–540, October, 1991. 相似文献
53.
54.
A piecewise linearization method based on the linearization of nonlinear ordinary differential equations in small intervals, that provides piecewise analytical solutions in each interval and smooth solutions everywhere, is developed for the study of the limit cycles of smooth and non-smooth, conservative and non-conservative, nonlinear oscillators. It is shown that this method provides nonlinear maps for the displacement and velocity which depend on the previous values through the nonlinearity and its partial derivatives with respect to time, displacement and velocity, and yields non-standard finite difference formulae. It is also shown by means of five examples that the piecewise linearization method presented here is more robust and yields more accurate (in terms of displacement, energy and frequency) solutions than the harmonic balance procedure, the method of slowly varying amplitude and phase, and other non-standard finite difference equations. 相似文献
55.
V. G. Osmolovski 《Journal of Mathematical Sciences》2006,132(3):304-312
Dependence of the phase transition temperature on the domain size is investigated for a double-well quadratic potential. It
is shown that for a domain whose boundary is subjected to a hydrostatical pressure, the temperature of phase transitions is
independent of the domain and the surface tension coefficient and depends exclusively on the properties of the elastic media.
If the displacement field vanishes on the boundary, then for sufficiently small domains, the temperature also does not depend
on the surface tension and domain size and is determined by properties of the elastic media only. Bibliography: 8 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 310, 2004, pp. 98–113. 相似文献
56.
I. J. Tchoupaeva 《Journal of Mathematical Sciences》2006,135(5):3409-3419
Some geometric theorems can be stated in coordinate-free form as polynomials in Grassman algebra and can be proven by the anticommutative Gröbner basis method. In this article, we analyze some properties of both sets of hypotheses and conclusions of the theorem. 相似文献
57.
We consider the radiation from nonoscillating dipoles traveling with constant velocity directed parallel or antiparallel to
the velocity of a homogeneous transparent moving medium. It is assumed that the medium in its rest frame is isotropic and
has no spatial dispersion. We obtain expressions for the radiative energy losses and estimate the polarization energy losses
of electric and magnetic dipoles of different orientations. In particular, it is shown that the energy loss of a source is
negative if it moves in the direction of the medium motion and the source velocity is less than the medium velocity. Estimates
for the energy losses of dipoles in the cases of an electron beam and a flow of a weakly dispersive medium are given.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 6, pp. 502–512, June 2006. 相似文献
58.
The excitation of eigen surface waves by tubular electron beams in cylindrical discharge devices is studied. The influence of the wave‐field azimuthal structure on the excitation efficiency and nonlinear stage of the plasmabeam instability is investigated both numerically and analytically. Analytical expressions for the saturation amplitude and excitation efficiency of the wave under study are derived. They are found to agree well with results obtained by numerical modelling of the plasma‐beam interaction presented in this paper. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
59.
In this paper we study root system generalizations of the quantum Bose-gas on the circle with pair-wise delta-function interactions.
The underlying symmetry structures are shown to be governed by the associated graded algebra of Cherednik's (suitably filtered)
degenerate double affine Hecke algebra, acting by Dunkl-type differential-reflection operators. We use Gutkin's generalization
of the equivalence between the impenetrable Bose-gas and the free Fermi-gas to derive the Bethe ansatz equations and the Bethe
ansatz eigenfunctions. 相似文献
60.
We study oscillation in a gyrotron with allowance for reflections from an output horn. Regions with different system behaviors,
such as stationary oscillation, self-modulation, and complex-dynamics regimes are found in the parameter plane. The scenarios
of appearance of chaotic oscillations are considered. It is shown that they can emerge via either a sequence of period-doubling
bifurcations or destruction of quasiperiodic motion. For chaotic attractors, Lyapunov exponents are calculated and their dimensions
are estimated on the basis of the Kaplan-Yorke formula. The dimension values turn out to be anomalously large, which is stipulated
by the presence of a large number of high-Q eigenmodes in the gyrotron cavity due to operation near the cutoff frequency of
an electrodynamic system.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 10, pp. 887–899, October 2006. 相似文献