全文获取类型
收费全文 | 280646篇 |
免费 | 2803篇 |
国内免费 | 930篇 |
专业分类
化学 | 149587篇 |
晶体学 | 4807篇 |
力学 | 11559篇 |
综合类 | 7篇 |
数学 | 30953篇 |
物理学 | 87466篇 |
出版年
2018年 | 2548篇 |
2017年 | 2575篇 |
2016年 | 4332篇 |
2015年 | 2795篇 |
2014年 | 4315篇 |
2013年 | 11960篇 |
2012年 | 8705篇 |
2011年 | 10723篇 |
2010年 | 7412篇 |
2009年 | 7188篇 |
2008年 | 9890篇 |
2007年 | 9834篇 |
2006年 | 9512篇 |
2005年 | 8835篇 |
2004年 | 8064篇 |
2003年 | 7258篇 |
2002年 | 7082篇 |
2001年 | 8102篇 |
2000年 | 6115篇 |
1999年 | 4845篇 |
1998年 | 4099篇 |
1997年 | 4027篇 |
1996年 | 3821篇 |
1995年 | 3659篇 |
1994年 | 3453篇 |
1993年 | 3343篇 |
1992年 | 3810篇 |
1991年 | 3736篇 |
1990年 | 3631篇 |
1989年 | 3581篇 |
1988年 | 3582篇 |
1987年 | 3590篇 |
1986年 | 3375篇 |
1985年 | 4490篇 |
1984年 | 4704篇 |
1983年 | 4016篇 |
1982年 | 4415篇 |
1981年 | 4099篇 |
1980年 | 4129篇 |
1979年 | 4258篇 |
1978年 | 4396篇 |
1977年 | 4262篇 |
1976年 | 4314篇 |
1975年 | 4156篇 |
1974年 | 4019篇 |
1973年 | 4374篇 |
1972年 | 2776篇 |
1971年 | 2231篇 |
1968年 | 2200篇 |
1967年 | 2160篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Makarov V. L. Khlobystov V. V. Kashpur E. F. Mikhal'chuk B. R. 《Ukrainian Mathematical Journal》2003,55(6):942-955
We construct an integral Newton-type interpolation polynomial with a continual set of nodes. This interpolant is unique and preserves an operator polynomial of the corresponding degree. 相似文献
82.
S. B. Krupanidhi 《Journal of Chemical Sciences》2003,115(5-6):775-788
Relaxor properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) and non-lead perovskite thin films have been analysed in terms of large frequency dispersion of dielectric response
at low temperatures. A wide spectrum of dielectric relaxation was observed in the frequency-dependent response of the imaginary
part of the dielectric permittivity. Transformation from normal ferroelectric to relaxor behaviour has been observed in the
case of the Ca substituting the BaTiO3 thin films. A number of techniques were exploited to investigate the wide spectrum of relaxation times in pulsed laser ablated
thin films.ac anddc electric field induced complex dielectric properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) thin films were studied as function of frequencies at different temperatures. Nonlinear behaviour of dielectric
susceptibility with respect to the amplitude of theac drive was observed at lower temperatures. The frequency dependence of transition temperatureT
m
(temperature of the maximum of dielectric constant) was studied using the Vogel-Fulcher relation.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
83.
Golovchenko A. V. Pil'o S. G. Brovarets V. S. Drach B. S. 《Russian Journal of General Chemistry》2003,73(11):1832-1833
Russian Journal of General Chemistry - 相似文献
84.
B. Bidgaray 《Numerical Methods for Partial Differential Equations》2003,19(3):284-300
In this article we derive new time discretizations for the numerical simulation of Maxwell‐Bloch equations. These discretizations decouple the equations, thus leading to improved efficiency. This approach may be combined with the fulfilment of physical properties, such as positiveness properties, which are not accounted for by classical schemes. Our time discretizations are moreover proved to be nonlinearly stable. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 284–300, 2003. 相似文献
85.
86.
A hybrid finite-element method, combining ideas from a modified method of characteristics and the streamline diffusion method, delivers accurate solutions to the advection–diffusion equation. An error analysis for the case of tensorial diffusion shows that the lowest-order version of the scheme, which allows one to use a symmetric linear solvers at each time step, possesses first-order accuracy in time and space. Numerical experiments demonstrate the scheme's ability to model advection-dominated transport of solute plumes without distorting sharp fronts. © 1995 John Wiley & Sons, Inc. 相似文献
87.
L. B. Parnovski 《Mathematische Nachrichten》1995,174(1):253-263
We investigate the asymptotic behaviour of the counting function of Dirichlet eigenvalues on some class of noncompact manifolds. We prove that in cases when the volume or the perimeter (the volume of the boundary) of the manifold is infinite, some additional (nonclassical) terms appear in the precise asymptotics. The coefficients at the classical terms in those are regularized in some special way volume (resp. perimeter) of the manifold. 相似文献
88.
Md. Nur Alam Per B. Zetterlund Masayoshi Okubo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4995-5004
Bimolecular termination in nitroxide‐mediated radical polymerization in miniemulsion has been investigated through the heating of a polystyrene–2,2,6,6‐tetramethylpiperidinyl‐1‐oxy macroinitiator and its 4‐hydroxy‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy analogue in an aqueous toluene dispersion with sodium dodecyl benzenesulfonate as a surfactant at 125 °C. The level of bimolecular termination by combination, evaluated from the high‐molecular‐weight shoulder, was higher in miniemulsion than in solution and increased with decreasing particle size. Quantitative analysis revealed that these results cannot be rationalized solely by nitroxide partitioning to the aqueous phase. The results are explained by an interface effect, by which nitroxide is adsorbed or located at the aqueous–organic interface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4995–5004, 2007 相似文献
89.
N. B. Voznesensky E. V. Gavrilov A. P. Zhevlakov V. K. Kirillovskiĭ P. V. Orlov 《Technical Physics》2007,52(2):271-275
Methods and schemes to inspect the EUV mirror shape are developed on the basis of a point diffraction interferometer with computer processing of interferograms. A measurement accuracy to within 0.001 of a wavelength in the visual range is achieved. 相似文献
90.
Frank W. Schmidt 《Linear and Multilinear Algebra》1991,30(3):229-230
This section appears from time to time. Contributions are invited, and should be submitted to R. C. Thompson, Mathematics Department, University of California, Santa Barbara, CA 93106. 相似文献