全文获取类型
收费全文 | 399篇 |
免费 | 11篇 |
国内免费 | 12篇 |
专业分类
化学 | 46篇 |
晶体学 | 1篇 |
数学 | 19篇 |
物理学 | 356篇 |
出版年
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 35篇 |
2012年 | 18篇 |
2011年 | 50篇 |
2010年 | 37篇 |
2009年 | 40篇 |
2008年 | 30篇 |
2007年 | 20篇 |
2006年 | 18篇 |
2005年 | 5篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 29篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有422条查询结果,搜索用时 31 毫秒
31.
The well known phenomenon of the increase of Tc of YBCO after slow cooling or low temperature annealing without change of the oxygen content, was found also for the YBCO like tetragonal superconductors of (CaxLa1−x)(LauBa1−u)2Cu3Oy (this compound has been previously denoted as CLBLCO, CLBCO or CaLaBaCuO). It has been observed at 150 and 100 °C for oxygen underdoped, optimally- and overdoped ceramics. The products retain their tetragonal unit cells. The possible reasons of this phenomenon are discussed. 相似文献
32.
D. De Barros L. Ortega Ch. Peroz F. Weiss P. Odier 《Physica C: Superconductivity and its Applications》2006,440(1-2):45-51
The synthesis of HgBCCO films by spray pyrolysis on single crystals is investigated. It is shown that in conditions where the precursor is expected to give Hg-1223, Hg-1212 grows on LaAlO3 (0 0 1) while Hg-1223 grows on MgO (0 0 1). The samples are analysed by X-ray pole figures, SEM and critical current measurements. Both samples were superconducting but the sample on MgO had a negligible Ic while 17 A was measured on LAO at 77 K (sf). These differences are analysed in terms of texture and microstructure and some conclusions concerning the growth are drawn. On LAO, the nucleation is probably epitaxial and the anisotropy of the growth inhibits the transformation into Hg-1223 while some interfacial contribution expected to occur on MgO makes this transformation easier. 相似文献
33.
Likely presence of superconductivity in layered nickelates of K2NiF4 structure is pointed out. 相似文献
34.
V. L. Ginzburg 《Journal of statistical physics》1969,1(1):3-24
The paper aims to elucidate the current status of the problem concerning the existence and observation of superfluid and superconducting states in the universe, that is, under cosmic conditions. Following an introduction, the paper discusses Bose-Einstein condensation, superfluidity, and superconductivity; possibilities for the occurrence of superfluidity and superconductivity under cosmic conditions; superconductivity of dense, degenerate electron plasma (large planets, white dwarfs); superfluidity and superconductivity in neutron stars; and finally superfluidity in a cosmological neutrino “sea.” 相似文献
35.
C M Srivastava 《Pramana》1985,25(5):617-633
Based on the assumption that in the groundbcs state the net gain in energy is equivalent to the repulsive electron-ion and electron-electron Darwin interactions, an expression
forT
c
has been obtained which depends on only a few atomic parameters. The theory provides a criterion for the occurrence of superconductivity
and yields satisfactory values ofT
c
for metals and alloys, and ternary chalcogenides and borides. It explains the difference inT
c
in the crystalline and amorphous states as well as the pressure dependence ofT
c
. The possibility of occurrence of high temperature superconductivity has been explored. 相似文献
36.
科技论文关键词撰写探讨 总被引:1,自引:0,他引:1
以《低温与超导》为例,探讨关键词写作中的一般规律以及需要注意的事项。还给出一些提高关键词写作质量的建议。 相似文献
37.
Kenji Kobayashi Hisatoshi Yokoyama 《Physica C: Superconductivity and its Applications》2010,470(20):1081-1084
The interplay between antiferromagnetism (AF) and superconductivity (SC) in cuprates is studied for the two-dimensional Hubbard model with a diagonal transfer t′, using a variational Monte Carlo method. Optimizing an improved function for strongly correlated values of U/t, we construct phase diagrams in the δ (doping rate)-t′/t space. It is found that the stable state is sensitive to the value of model parameters: For the extremely large values of U/t, a coexisting state is realized for t′/t ? −0.15, whose range of doping rate extends as t′/t increases. In contrast, for t′/t = −0.3, AF and SC states are mutually exclusive, and a coexisting state does not appear. As U/t decreases, the area of pure AF extends, and that of coexisting state shrinks. As a result, the coexisting state disappears for t′/t = −0.15 and U/t = 12, probable values for hole-doped cuprates. Compared with the t–J model, the Hubbard model has richer phases. 相似文献
38.
Zhaofei Li Jun Tang Masanori Watahiki 《Journal of Physics and Chemistry of Solids》2010,71(4):495-1635
We have successfully synthesized the α-FeSex binary tetragonal superconductors with nominal composition of FeSex (x=0.6-1.0) via conventional solid state reactions between Fe and Se sealed in quartz tubes. Fe and β-FeSe are the most commonly seen impurities in this binary system. A low-temperature annealing at 400 °C is found to be crucial to remove β-FeSe, which is the thermodynamic stable phase with hexagonal symmetry. For all the samples of FeSex, superconductivity is confirmed by magnetic measurements as well as resistivity measurements with their Tc at around 8 K. We noticed that their Tc does not vary with the different nominal Se amount. High-resolution synchrotron X-ray diffraction analysis revealed that the unit cell parameters of all these samples do not change within the error range, and their structure only tolerate the same very small amount of Se deficiency. Based on this study, we concluded that the α-FeSex superconductor only exist in a very narrow deficiency range. 相似文献
39.
This paper is concerned with the decay estimate of high-order energy for a class of special time-dependent structural damped systems represented by Fourier multipliers. This model is widely used in the fields of semiconductivity, superconductivity, electromagnetic waves, electrolyte and electrode materials, etc. 相似文献
40.
Wataru Higemoto Kanetada Nagamine Shinji Kuroda Koki Takita 《Molecular Crystals and Liquid Crystals》2013,570(2):51-56
Abstract The microscopic state of the positively charged light particle in the transition metal dichalcogenide 2H-NbSe2 was studied using the muon spin relaxation method (μ+SR) and muon level crossing resonance method (μ-LCR). Muons are expected to stay at interlayer position and behaves as a hydrogen like intercalant. We discuss the relation between conduction electron properties and the muon's behavior. 相似文献