全文获取类型
收费全文 | 6037篇 |
免费 | 56篇 |
国内免费 | 14篇 |
专业分类
化学 | 3565篇 |
晶体学 | 68篇 |
力学 | 171篇 |
数学 | 636篇 |
物理学 | 1667篇 |
出版年
2018年 | 44篇 |
2016年 | 51篇 |
2015年 | 44篇 |
2014年 | 63篇 |
2013年 | 199篇 |
2012年 | 147篇 |
2011年 | 166篇 |
2010年 | 112篇 |
2009年 | 116篇 |
2008年 | 178篇 |
2007年 | 189篇 |
2006年 | 184篇 |
2005年 | 205篇 |
2004年 | 187篇 |
2003年 | 153篇 |
2002年 | 140篇 |
2001年 | 82篇 |
2000年 | 72篇 |
1999年 | 82篇 |
1998年 | 54篇 |
1997年 | 79篇 |
1996年 | 106篇 |
1995年 | 100篇 |
1994年 | 61篇 |
1993年 | 69篇 |
1992年 | 64篇 |
1991年 | 62篇 |
1990年 | 70篇 |
1989年 | 62篇 |
1988年 | 72篇 |
1987年 | 83篇 |
1986年 | 57篇 |
1985年 | 67篇 |
1984年 | 83篇 |
1983年 | 64篇 |
1982年 | 80篇 |
1981年 | 63篇 |
1980年 | 89篇 |
1979年 | 61篇 |
1978年 | 84篇 |
1977年 | 75篇 |
1976年 | 64篇 |
1975年 | 78篇 |
1974年 | 50篇 |
1973年 | 48篇 |
1969年 | 42篇 |
1968年 | 47篇 |
1967年 | 47篇 |
1955年 | 59篇 |
1934年 | 44篇 |
排序方式: 共有6107条查询结果,搜索用时 14 毫秒
31.
32.
In this paper, we use the Leray-Schauder degree theory to obtain some information about the structure of the solution set of a large class of eigenvalue problems governed by a variational inequality. Applications are given to the unilateral postbuckling of a thin elastic plate. 相似文献
33.
Th. Friedrich I. Kath A. Moroianu U. Semmelmann 《Journal of Geometry and Physics》1997,23(3-4):259-286
A nearly parallel G2-structure on a seven-dimensional Riemannian manifold is equivalent to a spin structure with a Killing spinor. We prove general results about the automorphism group of such structures and we construct new examples. We classify all nearly parallel G2-manifolds with large symmetry group and in particular all homogeneous nearly parallel G2-structures. 相似文献
34.
Polymer lightguides of PMMA doped with the azo dyes methyl-red and N, N-dihexyl-4-amino-4'-nitro-azobenzene (DHANA) are investigated with respect to their opto-optical properties. The trans-cis photoisomerisation of the dyes leads to reversible polarization-dependent optically induced refractive index changes. The index changes are anisotropic. Birefringence is measured using index matched lightguides. The changes with respect to each polarization are determined by leaky mode spectroscopy and by using a half-integrated interferometer. These changes are intensity dependent and, with a suitable geometry, bistability at low intensities (3 mW/mm3) can be obtained. 相似文献
35.
36.
37.
Hans Thürach 《Analytical and bioanalytical chemistry》1878,17(1):367-367
38.
P. Lebeau Th. W. Richards und B. S. Merigold 《Fresenius' Journal of Analytical Chemistry》1913,52(12):789-790
Ohne Zusammenfassung 相似文献
39.
In this paper we provide an error bound estimate and an implicit multifunction theorem in terms of smooth subdifferentials and abstract subdifferentials. Then, we derive a subdifferential calculus and Fritz–John type necessary optimality conditions for constrained minimization problems. 相似文献
40.
Near-infrared laser photoacoustic detection of methane: the impact of molecular relaxation 总被引:1,自引:0,他引:1
A photoacoustic sensor has been developed for trace-gas monitoring using a near-infrared semiconductor laser emitting in the
2ν3 band of methane at 1.65 μm. The apparatus was designed for on-line process control in the manufacturing of the novel low-water-peak
fibres developed for optical telecommunications. The importance of collisional relaxation processes in the generation of the
photoacoustic signal is reported in the particular case of CH4 detection in dry O2 and O2–N2 mixtures. The negative influence of these effects results in a strongly reduced and phase-shifted photoacoustic signal, induced
by a fast resonant coupling between the vibrational states of methane and oxygen, associated with the slow relaxation of the
excited oxygen molecules. An unusual parabolic response of the sensor with respect to the methane concentration has been observed
and is discussed. Finally, the beneficial effect of several species, including water vapour and helium, acting as a catalyst
to hasten the relaxation of the CH4–O2 system, is demonstrated.
PACS 42.62.Fi; 33.20.Ea; 34.50.Ez 相似文献