全文获取类型
收费全文 | 23926篇 |
免费 | 3075篇 |
国内免费 | 2886篇 |
专业分类
化学 | 17877篇 |
晶体学 | 846篇 |
力学 | 1988篇 |
综合类 | 147篇 |
数学 | 1465篇 |
物理学 | 7564篇 |
出版年
2024年 | 27篇 |
2023年 | 252篇 |
2022年 | 452篇 |
2021年 | 424篇 |
2020年 | 649篇 |
2019年 | 558篇 |
2018年 | 565篇 |
2017年 | 670篇 |
2016年 | 896篇 |
2015年 | 792篇 |
2014年 | 1145篇 |
2013年 | 1754篇 |
2012年 | 2474篇 |
2011年 | 1504篇 |
2010年 | 1282篇 |
2009年 | 1471篇 |
2008年 | 1704篇 |
2007年 | 1862篇 |
2006年 | 1434篇 |
2005年 | 1269篇 |
2004年 | 1217篇 |
2003年 | 1023篇 |
2002年 | 926篇 |
2001年 | 839篇 |
2000年 | 803篇 |
1999年 | 625篇 |
1998年 | 560篇 |
1997年 | 375篇 |
1996年 | 388篇 |
1995年 | 328篇 |
1994年 | 321篇 |
1993年 | 247篇 |
1992年 | 206篇 |
1991年 | 162篇 |
1990年 | 113篇 |
1989年 | 106篇 |
1988年 | 92篇 |
1987年 | 65篇 |
1986年 | 56篇 |
1985年 | 50篇 |
1984年 | 35篇 |
1983年 | 15篇 |
1982年 | 33篇 |
1981年 | 15篇 |
1980年 | 26篇 |
1979年 | 21篇 |
1978年 | 10篇 |
1973年 | 9篇 |
1969年 | 5篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
141.
S. Loridant G. LucazeauT. Le Bihan 《Journal of Physics and Chemistry of Solids》2002,63(11):1983-1992
A high-pressure structural study of SrCeO3 has been performed at room temperature by Raman spectroscopy and X-ray diffraction up to 32 and 45 GPa, respectively. A first-order reversible phase transition is observed at about 12 GPa in both techniques. A second weak structural change, taking place between 18 and 25 GPa, can be suspected from Raman data. The increase in the number of Raman bands and diffraction lines is an indication that the symmetry is lowered and the compound does not evolve towards the ideal cubic perovskite structure. A Rietveld analysis of X-ray data was performed for the low-pressure phase and the atomic positions and the cell lattice parameters variations are reported in this paper. The volume compressibility derived from Raman modes (5.6×10−12 Pa−1), involving mainly bond-stretching for each type of polyhedron, is found to be close to the one obtained from volume cell variations measured by X-ray diffraction (7.9×10−12 Pa−1). 相似文献
142.
Young Wook Kim Seong-Deog Yang 《Proceedings of the American Mathematical Society》2006,134(11):3379-3390
We prove the existence of an infinite family of complete spacelike maximal surfaces with singularities in Lorentz-Minkowski three-space and study their properties. These surfaces are distinguished by their number of handles and have two elliptic catenoidal ends.
143.
We present exact numerical results for a symmetric layered medium (prism/Ag film/nonlinear dielectric/Ag film/prism) where
the middle dielectric slab is assumed to have a saturation-type nonlinearity. We show bistable behaviour in the power dependence
of the reflectivity ofp-polarized light under the condition when coupled surface modes are excited in the structure. Moreover, we study the effect
of saturation on the bistable behaviour to show that multivalued character is inhibited by saturation effects. The field distributions
corresponding to the minimum reflectivity states of the nonlinear structure are also presented. 相似文献
144.
Gu Chaohao 《数学年刊B辑(英文版)》1994,15(4):385-400
COMPLETEEXTREMALSURFACESOFMIXEDTYPEIN3-DIMENSIONALMINKOWSKISPACE¥GUCHAOHAO(InstituteofMathematics,FudanUniversity,Shanghai200... 相似文献
145.
We consider a two-dimensional Coulomb gas of positive and negative pointlike unit charges interacting via a logarithmic potential. The density (rather than the charge) correlation functions are studied. In the bulk, the form-factor theory of an equivalent sine-Gordon model is used to determine the density correlation length. At the surface of a rectilinear plain wall, the universality of the asymptotic behavior of the density correlations is suggested. A scaling analysis implies a local form of the compressibility sum rule near a hard wall. A symmetry of the Coulomb system with respect to the Möbius conformal transformation, which induces a gravitational source acting on the particle density, is established. Among the consequences, a universal term of the finite-size expansion of the grand potential is derived exactly for a disk geometry of the confining domain. 相似文献
146.
Erik Woldt 《Journal of Physics and Chemistry of Solids》2002,63(4):699-704
The paper investigates whether a change from a homogeneous to an inhomogeneous dislocation distribution, assumed to be caused by a slight additional deformation, can lead to an increase of the recrystallization temperature of a deformed metal. In this case, the higher temperature would indicate a more stable deformation structure despite the increase of stored energy. The recrystallization temperature is related to the growth rate. Hence, the steady state velocity of a recrystallization front moving either parallel or vertically to the stripes of a simplified two-dimensional heterogeneous dislocation distribution of parallel sections of higher and lower dislocation densities is calculated. The results show that if a front growths through the high and low density sections in series an overall slower rate despite higher mean dislocation density is, indeed, possible. However, growing in the parallel arrangement always leads to a higher growth rate compared with the homogeneous case of slightly less stored energy. Since in a real structure the faster growth is likely to succeed, the recrystallization temperature observed will be lowered with additional deformation in accordance with experimental experience. 相似文献
147.
V. P. Bubnov I. S. Krainskii E. E. Laukhina E. B. Yagubskii 《Russian Chemical Bulletin》1994,43(5):746-750
The effect of the parameters of the electric arc (helium pressure, current and voltage, clearance between electrodes) and of the peculiarities of the setup design (arrangement of electrodes, distance between the arc and the cooling surface, temperature of the soot condensation surface) on the yield of fullerenes has been studied. Conditions for producing soot with a C60 and C70 content up to 43% (toluene extract) have been found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 805–809, May, 1994.The authors are grateful to N. G. Spitsyna and A. V. Dubovitskii for the determination of the content of C60 and C70 fullerenes in the extract.The work was financially supported by the Russian Foundation for Basic Research (Project 93-03-18705). 相似文献
148.
J. -M. Douillard H. Malandrini T. Zoungrana F. Clauss S. Partyka 《Journal of Thermal Analysis and Calorimetry》1994,41(6):1205-1210
It is possible to estimate surface tension of high-energy solids combining the immersion microcalorimetry thermodynamics and Van Oss' model. In this study we have applied this method on talc and talc-chlorite samples in order to obtain thermodynamic values which permit to understand surface properties useful in the industrial applications of these solids. Some talcite samples are preferentially used in specific industrial applications because they are less hydrophobic or more lamellar. This method seems to be reliable to classify the solids and predict some properties. 相似文献
149.
YBa2Cu3O7-δ and Tl2Ba2CaCu2O8 thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate
quality requirements and the relation of thin film morphology, microstructure with microwave surface resistance were discussed. 相似文献
150.
It was shown by G. A. Jones and the first author in [8] that underlying any map on a compact orientable surface S there is a natural complex structure making S into a Riemann surface. In this paper we consider regular maps and enquire about the Weierstrass points on the underlying Riemann surface. We are particularly interested to know when these are geometric, i.e. whether they lie at vertices, face-centres or edge-centres of the map. 相似文献