全文获取类型
收费全文 | 890篇 |
免费 | 3篇 |
专业分类
化学 | 253篇 |
晶体学 | 13篇 |
力学 | 42篇 |
数学 | 168篇 |
物理学 | 417篇 |
出版年
2022年 | 11篇 |
2021年 | 17篇 |
2020年 | 15篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2017年 | 15篇 |
2016年 | 33篇 |
2015年 | 11篇 |
2014年 | 21篇 |
2013年 | 37篇 |
2012年 | 39篇 |
2011年 | 39篇 |
2010年 | 34篇 |
2009年 | 34篇 |
2008年 | 45篇 |
2007年 | 36篇 |
2006年 | 29篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 15篇 |
2002年 | 23篇 |
2001年 | 18篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 15篇 |
1984年 | 22篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1972年 | 8篇 |
1971年 | 8篇 |
1970年 | 6篇 |
排序方式: 共有893条查询结果,搜索用时 78 毫秒
81.
B. Ding M. E. Pemble A. V. Korovin U. Peschel S. G. Romanov 《Applied Physics A: Materials Science & Processing》2011,103(3):889-894
Hybrid metal-dielectric photonic crystals assembled from an opal film coated by a gold film are designed in order to realize
optical spectra that emanate from mixing Bloch modes in the opal and surface plasmon polaritons in corrugated gold films.
The photonic crystal provides a spatial template for the gold film profile and modifies the electromagnetic vacuum in the
vicinity to the gold layer. Reflectance spectroscopy was applied to deconvolute the plasmonic and photonic bandgap components
in the optical response of hybrid crystals as opposite to their mixed appearance in the transmission spectra. 相似文献
82.
On the basis of the methods of the theory of codimension-two bifurcations of cylindrically symmetric hydrodynamic flows, using
computer calculations, the motions of a fluid between rotating permeable coaxial cylinders are investigated near the intersection
of the bifurcations corresponding to the origin of a stationary regime of the Taylor vortex type and self-oscillations with
azimuthal waves. 相似文献
83.
The possibility of using a disclination approach to describe the structure and properties of fullerenes is discussed. It is
shown that the conversion of a planar carbon monolayer into a spherical macromolecule can be viewed as the result of introducing
12 disclinations with power π/3 into the original layer.
Fiz. Tverd. Tela (St. Petersburg) 40, 1178–1180 (June 1998) 相似文献
84.
V. G. Romanov 《Siberian Mathematical Journal》2006,47(1):135-151
In the space of variables (x, t) ∈ ? n+1, we consider a linear second-order hyperbolic equation with coefficients depending only on x. Given a domain D ? ? n+1 whose projection to the x-space is a compact domain Ω, we consider the question of construction of a stability estimate for a solution to the Cauchy problem with data on the lateral boundary S of D. The well-known method for obtaining such estimates bases on the Carleman estimates with an exponential-type weight function exp(2τ?(x, t)) whose construction faces certain difficulties in case of hyperbolic equations with variable coefficients. We demonstrate that if D is symmetric with respect to the plane t = 0 then we can take ?(x, t) to be the function ?(x, t) = s 2(x, x 0) ? pt 2, where s(x, x 0) is the distance between points x and x 0 in the Riemannian metric induced by the differential equation, p is some positive number less than 1, and the fixed point x 0 can either belong to the domain Ω or lie beyond it. As for the metric, we suppose that the sectional curvature of the corresponding Riemannian space is bounded above by some number k 0 ≥ 0. In case of space of nonpositive curvature the parameter p can be taken arbitrarily close to 1; in this case as p → 1 the stability estimates lead to a uniqueness theorem which describes exactly the domain of the solution continuation through S. It turns out that, in case of space of bounded positive curvature, construction of a Carleman estimate is possible only if the product of k 0 and sup x∈Ω s 2(x, x 0) satisfies some smallness condition. 相似文献
85.
Conditions are studied under which the contribution of the singular part of a measure to the (1,p)-capacity of an arbitrary condenser is zero. 相似文献
86.
The optical properties of suspensions are studied in a wide range of concentrations. An expression for the polarization operator is obtained taking into account the contributions of two-and three-particle correlations. The extinction length l and the transport length l* are calculated in terms of a model of hard spheres. A detailed comparison of the results of calculations with experimental data is performed. In calculations, the structure factor is determined in the Percus-Yevick approximation, while the form factor is taken into account in the Rayleigh-Gans approximation and in terms of the Mie theory. It is shown that taking into account the contribution of three-particle correlations improves the agreement of the theory with experiment. It is found that, in the range of high suspension concentrations, the optical parameters are more sensitive to the choice of the model for the structure factor than for the form factor. 相似文献
87.
88.
S. V. Bobylev I. A. Ovid’ko A. E. Romanov A. G. Sheinerman 《Physics of the Solid State》2006,48(2):264-271
The conditions of separation of an amorphous nanofilm from a crystalline substrate are theoretically studied in terms of a disclination-dislocation model for a crystal-glass interface. In this model, such an interface is characterized by a high density of disclinations and dislocations. A criterion for the separation of an amorphous nanofilm from a crystalline substrate is obtained. The critical nanofilm thickness above which a film begins to separate is calculated as a function of the characteristics of the disclination-dislocation system and the dilatation misfit. 相似文献
89.
Ballistic transport and spin-orbit interaction of two-dimensional electrons on a cylindrical surface
L. I. Magarill D. A. Romanov A. V. Chaplik 《Journal of Experimental and Theoretical Physics》1998,86(4):771-779
The components of the ballistic magnetoconductance tensor of a two-dimensional electron gas placed on a cylindrical sector
are calculated for various geometries. For a quasiclassical system a method is proposed for finding the conductance based
only on the Bohr-Sommerfeld quantization condition and not requiring a knowledge of the matrix elements of the velocity. The
effect of curvature of the surface on the spin-orbit interaction in a two-dimensional electron gas is investigated. As examples,
the microwave absorption and longitudinal conductance of a hollow cylindrical wire are calculated, and also the conductance
of a cylindrical sector. There are qualitative differences from planar systems, in particular the relative sign of the curvature
and the spin-orbit coupling constant becomes important.
Zh. éksp. Teor. Fiz. 113, 1411–1428 (April 1998) 相似文献
90.
The temperature dependences of magnetic susceptibility are employed for the first time to study the self-compensation of metastable centers with negative correlation energy in the As2S3 chalcogenide glass. The one-electron states of the metastable centers manifest themselves in the Curie paramagnetism at high temperatures, whereas for T≤77 K, one observes an enhancement of antiferromagnetism as a result of spontaneous dissociation of these states 2D 0 → D ++D ?. The observed self-compensation of the paramagnetic centers is similar to the spin-Peierls instability of magnetic lattices, which is supported by the existence of a double peak in the temperature dependence of inverse magnetic susceptibility. This peak identifies the spontaneous dissociation of two different metastable centers for T≤77 K. A comparative analysis of the data on magnetic susceptibility, optically induced absorption, and ESR shows that the one-electron paramagnetic states of these metastable centers (D 0) represent native hole and electronic defects formed by the chalcogen and arsenic dangling bonds, respectively. The self-compensation of the two types of metastable centers is enhanced in successive cooling runs 300 K → 3.5 K → 300 K → 3.5 K ... accompanied by optical pumping at an energy close to the Urbach absorption edge, which is reflected in a decrease in the Curie paramagnetism and an enhancement of the van Vleck paramagnetism of two-electron states with negative correlation energy (D ?). 相似文献