全文获取类型
收费全文 | 24118篇 |
免费 | 60篇 |
国内免费 | 46篇 |
专业分类
化学 | 10150篇 |
晶体学 | 409篇 |
力学 | 944篇 |
综合类 | 11篇 |
数学 | 3476篇 |
物理学 | 9234篇 |
出版年
2023年 | 14篇 |
2022年 | 180篇 |
2021年 | 368篇 |
2020年 | 377篇 |
2019年 | 552篇 |
2018年 | 1005篇 |
2017年 | 1117篇 |
2016年 | 1324篇 |
2015年 | 537篇 |
2014年 | 1099篇 |
2013年 | 1669篇 |
2012年 | 1499篇 |
2011年 | 1560篇 |
2010年 | 1778篇 |
2009年 | 1726篇 |
2008年 | 1687篇 |
2007年 | 1628篇 |
2006年 | 1418篇 |
2005年 | 890篇 |
2004年 | 627篇 |
2003年 | 326篇 |
2002年 | 318篇 |
2001年 | 311篇 |
2000年 | 616篇 |
1999年 | 349篇 |
1998年 | 448篇 |
1997年 | 426篇 |
1996年 | 111篇 |
1995年 | 37篇 |
1994年 | 36篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 10篇 |
1990年 | 19篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1971年 | 4篇 |
1968年 | 11篇 |
1967年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Journal of Structural Chemistry - Thermodynamic characteristics are calculated for aqueous alkanolamine solutions that are obtained by substituting alkyl radicals for the protons in the amino group... 相似文献
22.
23.
Dehghanpour-Sahron Ja’far Mahdavi-Amiri Nezam 《4OR: A Quarterly Journal of Operations Research》2021,19(4):473-499
4OR - Partitioning a given data-set into subsets based on similarity among the data is called clustering. Clustering is a major task in data mining and machine learning having many applications... 相似文献
24.
Planar laser-induced fluorescence visualisation is used to investigate nonuniformities in the flow of a hypersonic conical nozzle. Possible causes for the nonuniformity are outlined and investigated, and the problem is shown to be due to a small step at the nozzle throat. Entrainment of cold boundary layer gas is postulated as the cause of the signal nonuniformity.
PACS 47.80.Jk, 47.40.Ki, 47.60.+i 相似文献
25.
The semiclassical theory of proximity effects predicts a gap E g~?D/L 2 in the excitation spectrum of a long diffusive superconductor/normal-metal/superconductor (SNS) junction. Mesoscopic fluctuations lead to anomalously localized states in the normal part of the junction.As a result, a nonzero, yet exponentially small, density of states (DOS) appears at energies below E g. In the framework of the supermatrix nonlinear σ model, these prelocalized states are due to the instanton configurations with broken supersymmetry. The exact result for the DOS near the semiclassical threshold is found, provided the dimensionless conductance of the normal part G N is large. The case of poorly transparent interfaces between the normal and superconductive regions is also considered. In this limit, the total number of subgap states may be large. 相似文献
26.
Ya. V. Fattakhov M. F. Galyautdinov T. N. L’vova I. B. Khaibullin 《Technical Physics》1997,42(12):1457-1459
The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface
upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures
is discussed.
Zh. Tekh. Fiz. 67, 97–99 (December 1997) 相似文献
27.
A. I. Belogorokhov I. I. Ivanchik S. V. Ponomarev D. R. Khokhlov E. I. Slyn’ko 《JETP Letters》1996,63(5):353-357
Selective photoconductivity at frequency ω=155 cm− was discovered in PbTe(Ga) narrow-gap semiconductors at liquid-nitrogen temperatures. The corresponding energy is much lower
than all characteristic energies of the electronic spectrum of the semiconductor. The effect is attributed to optical excitation
of a local vibrational mode of an impurity center leading to delocalization of the electrons.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 5, 342–346 (10 March 1996) 相似文献
28.
D. V. Vyalykh A. M. Shikin G. V. Prudnikova A. Yu. Grigor’ev A. G. Starodubov V. K. Adamchuk 《Physics of the Solid State》2002,44(1):164-170
This paper reports on the first experimental observation of quantum-well states and sp-type resonances in thin single-crystal gold, silver, and copper layers formed on single-crystal W(110) surfaces, which result from spatial localization of Bloch-type electronic wave functions in a quantum well with potential barriers at the vacuum/metal and metal/W(110) interfaces. The quantization of the valence-band electronic structure in Au/W(110), Ag/W(110), and Cu/W(110) systems was studied experimentally using angle-resolved photoelectron spectroscopy. 相似文献
29.
30.
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