全文获取类型
收费全文 | 361274篇 |
免费 | 2995篇 |
国内免费 | 1101篇 |
专业分类
化学 | 193284篇 |
晶体学 | 5740篇 |
力学 | 14749篇 |
综合类 | 9篇 |
数学 | 41870篇 |
物理学 | 109718篇 |
出版年
2020年 | 3161篇 |
2019年 | 3559篇 |
2018年 | 4815篇 |
2017年 | 4798篇 |
2016年 | 6863篇 |
2015年 | 4002篇 |
2014年 | 6474篇 |
2013年 | 15984篇 |
2012年 | 11891篇 |
2011年 | 14293篇 |
2010年 | 10359篇 |
2009年 | 10135篇 |
2008年 | 13637篇 |
2007年 | 13640篇 |
2006年 | 12753篇 |
2005年 | 11526篇 |
2004年 | 10447篇 |
2003年 | 9502篇 |
2002年 | 9194篇 |
2001年 | 10191篇 |
2000年 | 7892篇 |
1999年 | 5991篇 |
1998年 | 5120篇 |
1997年 | 5063篇 |
1996年 | 4764篇 |
1995年 | 4207篇 |
1994年 | 4247篇 |
1993年 | 4188篇 |
1992年 | 4533篇 |
1991年 | 4563篇 |
1990年 | 4449篇 |
1989年 | 4372篇 |
1988年 | 4281篇 |
1987年 | 4276篇 |
1986年 | 4052篇 |
1985年 | 5315篇 |
1984年 | 5519篇 |
1983年 | 4644篇 |
1982年 | 4986篇 |
1981年 | 4721篇 |
1980年 | 4515篇 |
1979年 | 4824篇 |
1978年 | 4998篇 |
1977年 | 4923篇 |
1976年 | 4989篇 |
1975年 | 4753篇 |
1974年 | 4684篇 |
1973年 | 5011篇 |
1972年 | 3305篇 |
1971年 | 2817篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
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
22.
A new geometrical method to determine the surface damage threshold for ultrashort pulses is presented. It consists in the formation of a surface damage profile by a movement of the sample across the laser beam focus. A single measurement of the maximum transversal dimension of this damage profile, which depends solely on the laser beam power, is used to calculate the local damage threshold intensity. It is also theoretically shown that the damage in the transverse dimension can be controlled under the diffraction-limited spot. 相似文献
23.
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
24.
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
25.
Let ir(G) and γ(G) be the irredundance number and the domination number of a graph G, respectively. A graph G is called irredundance perfect if ir(H)=γ(H), for every induced subgraph H of G. In this article we present a result which immediately implies three known conjectures on irredundance perfect graphs. © 2002 Wiley Periodicals, Inc. J Graph Theory 41: 292–306, 2002 相似文献
26.
E. P. Gordov 《Russian Physics Journal》1981,24(11):1039-1041
An evolution operatior is described, which acts on the operators of a problem to take it into the solutions of the corresponding problem of semiclassical electrodynamics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 66–69, November, 1981. 相似文献
27.
A. R. Volkov B. V. Shul'gin T. I. Polupanova V. N. Lebedev A. A. Nagornyi V. L. Petrov Yu. F. Kargin 《Journal of Applied Spectroscopy》1991,54(6):585-590
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 6, pp. 970–975, June, 1991. 相似文献
28.
29.
30.
We establish soliton-like asymptotics for finite energy solutions to the Schrödinger equation coupled to a nonrelativistic classical particle. Any solution with initial state close to the solitary manifold converges to a sum of a travelling wave and an outgoing free wave. The convergence holds in global energy norm. The proof uses spectral theory and the symplectic projection onto the solitary manifold in the Hilbert phase space. 相似文献