全文获取类型
收费全文 | 36506篇 |
免费 | 296篇 |
国内免费 | 98篇 |
专业分类
化学 | 17210篇 |
晶体学 | 504篇 |
力学 | 1409篇 |
综合类 | 11篇 |
数学 | 5602篇 |
物理学 | 12164篇 |
出版年
2022年 | 299篇 |
2021年 | 515篇 |
2020年 | 534篇 |
2019年 | 706篇 |
2018年 | 1162篇 |
2017年 | 1262篇 |
2016年 | 1576篇 |
2015年 | 757篇 |
2014年 | 1352篇 |
2013年 | 2364篇 |
2012年 | 2022篇 |
2011年 | 2172篇 |
2010年 | 2212篇 |
2009年 | 2085篇 |
2008年 | 2244篇 |
2007年 | 2090篇 |
2006年 | 1894篇 |
2005年 | 1313篇 |
2004年 | 1064篇 |
2003年 | 678篇 |
2002年 | 654篇 |
2001年 | 530篇 |
2000年 | 835篇 |
1999年 | 520篇 |
1998年 | 597篇 |
1997年 | 579篇 |
1996年 | 294篇 |
1995年 | 174篇 |
1994年 | 164篇 |
1993年 | 180篇 |
1992年 | 183篇 |
1991年 | 182篇 |
1990年 | 151篇 |
1989年 | 146篇 |
1988年 | 151篇 |
1987年 | 201篇 |
1986年 | 165篇 |
1985年 | 211篇 |
1984年 | 203篇 |
1983年 | 165篇 |
1982年 | 183篇 |
1981年 | 202篇 |
1980年 | 194篇 |
1979年 | 184篇 |
1978年 | 182篇 |
1977年 | 174篇 |
1976年 | 157篇 |
1975年 | 166篇 |
1974年 | 133篇 |
1973年 | 127篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Mari Grobbelaar‐Van Dalsen 《Mathematical Methods in the Applied Sciences》2004,27(11):1301-1315
This paper is concerned with well‐posedness results for a mathematical model for the transversal vibrations of a two‐dimensional hybrid elastic structure consisting of a rectangular Reissner–Mindlin plate with a Timoshenko beam attached to its free edge. The model incorporates linear dynamic feedback controls along the interface between the plate and the beam. Classical semigroup methods are employed to show the unique solvability of the coupled initial‐boundary‐value problem. We also show that the energy associated with the system exhibits the property of strong stability. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
52.
L. M. Vasilyak M. N. Vasil’ev S. P. Vetchinin D. N. Polyakov V. E. Fortov 《Journal of Experimental and Theoretical Physics》2003,96(3):440-443
The action of an electron beam on ordered dust structures in glow and low-pressure RF discharges was studied experimentally. The electron beam produces destruction and dynamic displacement of the dust structure. In the center of a dust structure, an electron beam with a low electron energy (tens of eV) at currents up to 1 mA caused structural disordering and “melting” in the region of its action but did not excite external crystal regions. Local action of an electron beam with a high electron energy (25 keV) and a beam current above 10 mA caused deformation of the whole dust structure and shifted it in the horizontal direction so that it was carried away from the RF discharge zone. The effect of dust structure displacements can be used to locally remove particles from a plasma. 相似文献
53.
We consider the application of asymptotic methods of nonlinear mechanics (the Krylov-Bogolyubov-Mitropol'skii method) and
the method of separation of motions in nonlinear systems for the construction of an approximate solution of a nonlinear equation
that describes a nonstationary wave process.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 3, pp. 357–371, March, 1998. 相似文献
54.
Yu. A. Mitropol’skii Nguyen Dong Anh Nguyen Dyk Tynh 《Ukrainian Mathematical Journal》1998,50(11):1731-1737
We construct the second approximation for random oscillations described by the Van der Pol equation which are under the action
of a broadband random process.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 11, pp. 1517–1521, November, 1998. 相似文献
55.
An expression for the probability of thermally activated tunneling ionization in an electric field in the presence of a magnetic
field is obtained. It is shown that the logarithm of the ionization probability is proportional to the squared electric field,
and the coefficient of proportionality decreases with increasing magnetic field.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 10, 763–767 (25 November 1998) 相似文献
56.
57.
We consider an optimal growth (multi-sector) model with nonconvex technology. Using the Clarke results on generalized gradients, we prove that the value function has left and right derivatives with respect to the initial capital stock, without requiring supermodularity assumptions. 相似文献
58.
Microencapsulation of DNA Within alginate microspheres and crosslinked chitosan membranes for in vivo application 总被引:4,自引:0,他引:4
T. Alexakis D. K. Boadi D. Quong A. Groboillot I. O’Neill D. Poncelet R. J. Neufeld 《Applied biochemistry and biotechnology》1995,50(1):93-106
Calf thymus DNA was microencapsulated within crosslinked chitosan membranes, or immobilized within chitosan-coated alginate
microspheres. Microcapsules were prepared by interfacial polymerization of chitosan, and alginate microspheres formed by emulsification/
internal gelation. Diameters ranged from 20 to 500 Μm, depending on the formulation conditions. Encapsulated DNA was quantifiedin situ by direct spectrophotometry (260 nm) and ethidium bromide fluorimetry, and compared to DNA measurements on the fractions
following disruption and dissolution of the microspheres. Approximately 84% of the DNA was released upon core dissolution
and membrane disruption, with 12% membrane bound. The yield of encapsulation was 96%. Leakage of DNA from intact microspheres/capsules
was not observed. DNA microcapsules and microspheres were recovered intact from rat feces following gavage and gastrointestinal
transit. Higher recoveries (60%) and reduced shrinkage during transit were obtained with the alginate microspheres. DNA was
recovered and purified from the microcapsules and microspheres by chromatography and differential precipitation with ethanol.
This is the first report of microcapsules or microspheres containing biologically active material (DNA) being passed through
the gastrointestinal tract, with the potential for substantial recovery. 相似文献
59.
60.
E. D. Mishina N. É. Sherstyuk V. O. Val’dner A. V. Mishina K. A. Vorotilov V. A. Vasil’ev A. S. Sigov M. P. De Santo E. Cazzanelli R. Barberi Th. Rasing 《Physics of the Solid State》2006,48(6):1210-1213
Ferroelectric composite two-dimensional ferroelectric/aluminum oxide nanostructures were studied. A porous aluminum oxide matrix was used as a template into which a ferroelectric precursor was introduced, followed by annealing. The prepared nanostructures were studied using optical second harmonic generation and micro-Raman scattering. 相似文献