全文获取类型
收费全文 | 374367篇 |
免费 | 4912篇 |
国内免费 | 1808篇 |
专业分类
化学 | 195603篇 |
晶体学 | 6028篇 |
力学 | 17507篇 |
综合类 | 31篇 |
数学 | 42082篇 |
物理学 | 119836篇 |
出版年
2020年 | 2902篇 |
2019年 | 3124篇 |
2018年 | 3809篇 |
2017年 | 3725篇 |
2016年 | 6051篇 |
2015年 | 4162篇 |
2014年 | 6259篇 |
2013年 | 16662篇 |
2012年 | 12964篇 |
2011年 | 16220篇 |
2010年 | 10883篇 |
2009年 | 10969篇 |
2008年 | 14835篇 |
2007年 | 14759篇 |
2006年 | 14093篇 |
2005年 | 12842篇 |
2004年 | 11785篇 |
2003年 | 10270篇 |
2002年 | 10159篇 |
2001年 | 11738篇 |
2000年 | 8990篇 |
1999年 | 7034篇 |
1998年 | 5717篇 |
1997年 | 5637篇 |
1996年 | 5424篇 |
1995年 | 4939篇 |
1994年 | 4736篇 |
1993年 | 4707篇 |
1992年 | 5050篇 |
1991年 | 5174篇 |
1990年 | 4702篇 |
1989年 | 4663篇 |
1988年 | 4705篇 |
1987年 | 4534篇 |
1986年 | 4290篇 |
1985年 | 6026篇 |
1984年 | 6171篇 |
1983年 | 5019篇 |
1982年 | 5358篇 |
1981年 | 5162篇 |
1980年 | 5006篇 |
1979年 | 5107篇 |
1978年 | 5217篇 |
1977年 | 5135篇 |
1976年 | 5200篇 |
1975年 | 4874篇 |
1974年 | 4842篇 |
1973年 | 4951篇 |
1972年 | 3284篇 |
1971年 | 2566篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
991.
D. K. Kuznetsov I. S. Baturin V. Ya. Shur N. Menou C. Muller T. Schneller A. Sternberg 《Physics of the Solid State》2006,48(6):1174-1176
The effect of irradiation with electrons and neutrons and of exposure to synchrotron radiation on cyclic switching of polarization in thin films of lead zirconate titanate Pb(Zr,Ti)O3 (PZT) was studied. It is shown that variations in the shape of switching currents are due to the generation of a spatially nonuniform bound internal field with account for an increase in the rate of bulk screening caused by irradiation. A correlation between structural variations and the evolution of the switching current measured during and after irradiation is established. 相似文献
992.
Masanobu Haraguchi David F. P. Pile Toshihiro Okamoto Masuo Fukui Dmitri K. Gramotnev 《Optical Review》2006,13(4):228-230
We have numerically shown the existence of coupled wedge plasmons (CWPs) which propagates along a nano gap of a twin metal
wedge. The CWPs are formed by wedge plasmons which can interact with each other. The dispersion relations of the wavenumber,
propagation distance, and beam area of CWPs, are described and show that the characteristics of CWPs are similar to those
of wedge plasmons and of gap plasmons. We also propose a new plasmon waveguide composed of twin metal wedges with a nano gap. 相似文献
993.
V. P. Nekhoroshev Yu. P. Turov A. V. Nekhorosheva V. D. Ogorodnikov K. N. Gaevoi 《Russian Journal of Applied Chemistry》2006,79(5):833-840
The composition and structure of low-molecular-weight products of thermal oxidative degradation of atactic polypropylene were studied. 相似文献
994.
V. A. Zayats A. N. Nikolaevskii T. A. Filippenko O. P. Kniga G. A. Tikhonova 《Russian Journal of Applied Chemistry》2006,79(10):1651-1654
Specific features of the initiated oxidation of polyethylene and its low-molecular-weight analogue tridecane, associated with the occurrence of the process in the short-chain mode, were studied. 相似文献
995.
V. P. Korolev 《Russian Journal of Applied Chemistry》2006,79(11):1779-1784
An equation for the standard enthalpy of solvation of a compound in a binary solvent is derived. The enthalpies of solvation in water-methanol mixtures are estimated for 1,3-propane-and 1,6-hexanediols, 1,2,4-butane-and 1,3,5-pentanetriols, 2-methoxy-and 2-propoxyethanols, and diethylene glycol. The enthalpy of solvation of 1,2-dimethoxyethane in the water-methanol mixed solvent is determined experimentally. 相似文献
996.
Improving Construction for Connected Dominating Set with Steiner Tree in Wireless Sensor Networks 总被引:2,自引:0,他引:2
Manki Min Hongwei Du Xiaohua Jia Christina Xiao Huang Scott C.-H. Huang Weili Wu 《Journal of Global Optimization》2006,35(1):111-119
The connected dominating set plays an important role in ad hoc wireless networking. Many constructions for approximating the minimum connected dominating set have been proposed in the
literature. In this paper, we propose a new one with Steiner tree, which produces approximation solution within a factor of
6.8 from optimal. This approximation algorithm can also be implemented distributedly. 相似文献
997.
A. P. Tyutnev R. Sh. Ikhsanov E. L. Grin’ G. P. Safonov A. I. Kononenko A. M. Sorokin I. V. Rudenko 《Polymer Science Series A》2006,48(11):1190-1195
A general theory of the phenomenon of recovered voltage in polymers was considered on the basis of representation of an actual poling process by a discrete set of Debye relaxators. Examples of numerical solution of the direct and inverse problems are given. A correlation expression between intentionally aged polymer specimens and recovered-voltage curves was proposed for use in the assessment of the material state of a polymer under actual service conditions. It was shown that it is sufficient to restrict consideration to three relaxation processes in analysis of the phenomenon. 相似文献
998.
999.
1000.
N.A. Buznikov A.S. Antonov A.B. Granovsky C.G. Kim C.O. Kim X.P. Li S.S. Yoon 《Journal of magnetism and magnetic materials》2006
The giant magnetoimpedance effect in composite wires consisting of a non-magnetic inner core and soft magnetic shell is studied theoretically. It is assumed that the magnetic shell has a helical anisotropy. The current and field distributions in the composite wire are found by means of a simultaneous solution of Maxwell equations and the Landau–Lifshitz equation. The expressions for the diagonal and off-diagonal impedance are obtained for low and high frequencies. The dependences of the impedance on the anisotropy axis angle and the shell thickness are analyzed. Maximum field sensitivity is shown to correspond to the case of the circular anisotropy in the magnetic shell. It is demonstrated that the optimum shell thickness to obtain maximum impedance ratio is equal to the effective skin depth in the magnetic material. 相似文献