全文获取类型
收费全文 | 2388篇 |
免费 | 181篇 |
国内免费 | 10篇 |
专业分类
化学 | 1786篇 |
晶体学 | 26篇 |
力学 | 65篇 |
数学 | 274篇 |
物理学 | 428篇 |
出版年
2023年 | 17篇 |
2022年 | 86篇 |
2021年 | 85篇 |
2020年 | 72篇 |
2019年 | 111篇 |
2018年 | 77篇 |
2017年 | 69篇 |
2016年 | 127篇 |
2015年 | 93篇 |
2014年 | 93篇 |
2013年 | 180篇 |
2012年 | 146篇 |
2011年 | 131篇 |
2010年 | 101篇 |
2009年 | 95篇 |
2008年 | 126篇 |
2007年 | 133篇 |
2006年 | 110篇 |
2005年 | 78篇 |
2004年 | 76篇 |
2003年 | 69篇 |
2002年 | 63篇 |
2001年 | 56篇 |
2000年 | 37篇 |
1999年 | 31篇 |
1998年 | 11篇 |
1997年 | 15篇 |
1996年 | 13篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 23篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 13篇 |
1980年 | 20篇 |
1979年 | 8篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1973年 | 6篇 |
1971年 | 6篇 |
1862年 | 8篇 |
排序方式: 共有2579条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
The main result of the paper is a theorem, using which a new proof of Roth’s theorem is obtained, a new solvability criterion
for the matrix equation AX-YB = C is proved, a formula for a particular solution of the latter is derived, and the least of
the orders of square nonsingular matrices containing a given rectangular matrix as a submatrix is determined. Bibliography:
5 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 323, 2005, pp. 15–23. 相似文献
5.
Bending of optical fiber leads to an induced-anisotropy in the index profile that influences many important guiding fiber parameters. An analytical method is described for the measurement of refractive-index-wavelength dispersion in bent optical fibers. Multiple-beam Fizeau fringes technique at transmission is used to analyze the opto-mechanical properties and induced-index anisotropy in a standard single-mode fiber undergoes pure mechanical macrobending. The shift in Fizeau fringes is employed to evaluate the dispersion of the cladding material of the bent fiber. The radial variations in Cauchy’s coefficients and the associated variations of some fiber parameters due to macrobending are carried out. The radial profiles of some material parameters such as oscillation energy, dispersion energy, lattice energy and material dispersion are measured as well. The presented method is capable to achieve quantitative and qualitative measurements, which is not available with other methods. The method has a good index resolution in the order of 10−4 and spatial resolution of 1.3 μm. 相似文献
6.
Al.Th. Kermanidis D.G. Stamatelos G.N. Labeas Sp.G. Pantelakis 《Theoretical and Applied Fracture Mechanics》2006,45(2):148-158
The synergetic effect of corrosion and corrosion induced hydrogen embrittlement damage processes which occur at local scale has been found to result in a dramatic macroscopic tensile ductility loss of the 2024 aluminum alloy. In the present work, the tensile behaviour of corroded 2024 T351 specimens has been estimated on the basis of FE analysis by taking into account the local material properties in the damaged areas. A parametric study is involved to account for the effect of thickness in the results. Calculated tensile properties obtained with the analysis agree well with experimental data. 相似文献
7.
Mohamed Hilmy Elnagdi Ramadan Maawad Abdel-Motaleb Mona Mustafa Mohamed Foad Zayed Eman Moustafa Kamel 《Journal of heterocyclic chemistry》1987,24(6):1677-1681
The behaviour of several 2-amino-3-cyano-4H-pyran derivatives toward a variety of nucleophilic reagents is reported. 相似文献
8.
L. V. Giurgiu M. N. Grecu X. Filip O. Raita Al. Darabont D. Gavre J. Blasco 《Applied magnetic resonance》2003,24(3-4):351-360
We report an electron paramagnetic resonance (EPR) investigation of the spin dynamics in the paramagnetic regime of the colossal magnetoresistive manganites La2/3Ca1/3Mn1?x Me x O3 (Me=Al, In;x≤0.05). The temperature dependences of the EPR linewidth and integral intensity have been analyzed in terms of the bottleneck spin relaxation and small-polaron hopping models. The exchange coupling integral between Mn3+ and Mn4+ ions and the polaron activation energy decrease with increasing doping level. A discussion is given concerning the factors which could explain the observed changes. 相似文献
9.
10.
Summary Transfer chemical potentials have been determined from measured solubilities for four uncharged encapsulated iron(II) complexes containing three diimine ligating moieties and O3BOBu-n and O3BF capping groups, in H2O–MeOH andt-BuOH–H2O solvent mixtures, The trends in transfer chemical potentials are discussed in terms of the natures of the encapsulating ligands, and are compared with those for a selection of other iron(II)-diimine complexes. 相似文献