全文获取类型
收费全文 | 5268篇 |
免费 | 763篇 |
国内免费 | 631篇 |
专业分类
化学 | 2729篇 |
晶体学 | 66篇 |
力学 | 1477篇 |
综合类 | 34篇 |
数学 | 659篇 |
物理学 | 1697篇 |
出版年
2024年 | 9篇 |
2023年 | 65篇 |
2022年 | 116篇 |
2021年 | 158篇 |
2020年 | 236篇 |
2019年 | 192篇 |
2018年 | 199篇 |
2017年 | 167篇 |
2016年 | 229篇 |
2015年 | 200篇 |
2014年 | 248篇 |
2013年 | 437篇 |
2012年 | 257篇 |
2011年 | 291篇 |
2010年 | 278篇 |
2009年 | 326篇 |
2008年 | 326篇 |
2007年 | 350篇 |
2006年 | 336篇 |
2005年 | 281篇 |
2004年 | 264篇 |
2003年 | 272篇 |
2002年 | 188篇 |
2001年 | 139篇 |
2000年 | 134篇 |
1999年 | 113篇 |
1998年 | 105篇 |
1997年 | 121篇 |
1996年 | 96篇 |
1995年 | 73篇 |
1994年 | 80篇 |
1993年 | 54篇 |
1992年 | 60篇 |
1991年 | 40篇 |
1990年 | 35篇 |
1989年 | 24篇 |
1988年 | 33篇 |
1987年 | 28篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 20篇 |
1983年 | 3篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有6662条查询结果,搜索用时 515 毫秒
21.
Luminescence properties of anodic aluminum oxide films with organic luminophores embedded into pores
V. V. Gruzinskii A. V. Kukhto A. M. Mozalev V. F. Surganov 《Journal of Applied Spectroscopy》1997,64(4):497-502
Luminescence properties of porous anodic aluminum oxide films formed in a 0.6 M solution of citric acid and luminescence of
paraterphenyl, perylene, coumarin 7, and rhodamine 6G dyes adsorbed by the films are investigated. The nature of emitting
centers in anodic aluminum oxide is revealed. Intense photoluminescence of all tested dyes embedded into pores of anodic aluminum
oxide has been found. A redshift of fluorescence spectra of dyes adsorbed by the matrix and emergence of an additional longwave
band have been detected. Data obtained can be used in developing new thin-film luminescent coatings for future applications
in optoelectronics and molecular electronics.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No 4, pp. 483–488, July–August, 1997. 相似文献
22.
对经过阴极还原处理后的多孔硅样片进行了光致发光测试和稳定性测试.实验结果表明这种处理能明显改善多孔硅的发光稳定性,使其表面结构更加稳定.利用原子力显微镜对不同还原时间的多孔硅微结构及形貌进行了比较,在一定范围内随着还原时间的增长多孔硅表面粗糙度增大,PL谱增强. 相似文献
23.
Arup Baksi Bidyut Kumar Roy Rasajit Kumar Bera 《Mathematical and Computer Modelling》2006,44(11-12):1069-1079
The fundamental equations of the problems of generalized thermoelasticity with one relaxation parameter including heat sources in infinite rotating magneto-thermo-viscoelastic media have been derived in the form of a vector matrix differential equation in the Laplace transform domain for a one dimensional problem. These equations have been solved by the eigenvalue approach to determine deformations, stress, and temperature. The results have been compared to those available in the existing literature. The graphs have been drawn to show the effect of rotation in the medium. 相似文献
24.
Christodoulos Athanasiadis Nikolaos Berketis 《Mathematical Methods in the Applied Sciences》2006,29(1):27-48
A spherical electromagnetic wave propagating in a chiral medium is scattered by a bounded chiral obstacle which can have any of the usual properties. Reciprocity and general scattering theorems, relating the scattered fields due to scattering of waves from a point source put in any two different locations are established. Applying the general scattering theorem for appropriate locations and polarizations of the point source we prove an associated forward scattering theorem. Mixed scattering relations, relating the scattered fields due to a plane wave and the far‐field patterns due to a spherical wave, are also established. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
25.
The aim of this paper is to introduce a new functional in thestudy of swelling porous elastic soils saturated by a fluid.This new functional is a useful tool; it allows us to provethe existence of solutions in the case of a compressible fluid.We also prove the stability of solutions and the exponentialdecay in the case of an incompressible fluid. We study as wellthe continuous dependence with respect to the initial time. 相似文献
26.
The paper deals with the stress, displacement, pore and fissure pressures fields induced by the drilling and/or the pressurization of a vertical borehole in a formation of water-saturated porous media with double porosity. The solution includes the boundary condition of non-hydrostatic in situ state of stress. The solid skeleton is assumed to behave as a linearly poroelastic material with compressible constituents. The analytical solution is derived in Laplace’s space and transformed to the time domain using a numerical inversion technique. The histories of pore and fissure pressures are illustrated to show the influence of permeabilities of the pore and fissure systems. 相似文献
27.
氯柱硼镁石在氯化镁水溶液中相转化平衡液相的红外光谱分析 总被引:5,自引:0,他引:5
采用差示FTIR光谱技术,研究了氯柱硼镁石在30℃下浓度为0.5,12和18%MgCl_2水溶液中溶解及相转化平衡饱和水溶液中硼氧配阴离子的FTIR光谱。给出了溶液中硼氧配阴离子的FTIR光谱振动频率的归属,515cm~(-1)为单和二硼氧配阴离子特征峰,630cm~(-1)为三硼氧配阴离子特征峰,550cm~(-1)为四硼氧配阴离子特征峰。对饱和水溶液中硼氧配阴离子的存在形式及其相互作用以及与相转化析出固相的关系进行了讨论。 相似文献
28.
29.
A. V. Pastukhov V. A. Davankov E. V. Sidorova E. I. Shkol’nikov V. V. Volkov 《Russian Chemical Bulletin》2007,56(3):484-493
An automated procedure was developed for monitoring fast changes in the size of spherical samples of polymers during their
contact with a solvent or drying. The kinetics of bulk deformation in these processes was studied for a series of cross-linked
polymers, viz., gel-type and porous styrene—divinylbenzene copolymers and poly(divinylbenzenes), and hypercrosslinked polystyrenes. Gel,
macroporous, and hypercrosslinked polystyrenes are substantially different in the rate, mechanism, and degree of swelling,
which is associated with the principal differences in their physical structures. An unusual effect of a sharp decrease followed
by a temporary increase in the volume of porous polystyrene and poly(divinylbenzene) materials were observed during desorption
(evaporation) of organic solvents. Water desorption is accompanied by an excessive bulk compression of porous granules giving
rise to negative deformations, which gradually relax to the state equilibrium for the dry polymer. The results of dynamic
desorption porometry (for water desorption) are indicative of a bimodal size distribution of micropores in hypercrosslinked
polystyrene.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 467–476, March, 2007. 相似文献
30.
Reaction diffusion systems on cylindrical domains with terms that vary rapidly and periodically in the unbounded direction can be analyzed by averaging techniques. Here, using iterated normal form transformations and Gevrey regularity of bounded solutions, we prove a result on exponential averaging for such systems, i.e., we show that traveling wave solutions can be described by a spatially homogenous equation and exponentially small remainders. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献