全文获取类型
收费全文 | 104篇 |
免费 | 1篇 |
专业分类
化学 | 4篇 |
晶体学 | 6篇 |
数学 | 5篇 |
物理学 | 90篇 |
出版年
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2013年 | 2篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 7篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有105条查询结果,搜索用时 21 毫秒
1.
A. A. Mukhin V. Yu. Ivanov V. D. Travkin S. P. Lebedev A. Pimenov A. Loidl A. M. Balbashov 《JETP Letters》1998,68(4):356-362
The electrical conductivity, magnetic susceptibility, magnetization, and submillimeter (v=5∓20 cm−1) permittivity and dynamic conductivity of La1−x
Sr
x
MnO3 (0≤x≤ 0.45) single crystals are investigated. The anomalies in the temperature dependences of these quantities are identified
with diverse magnetic and structural phase transformations, including antiferromagnetic and ferromagnetic ordering, structural
transitions between strongly distorted (Jahn-Teller) and weakly distorted (pseudocubic) orthorhombic phases, structural transitions
to a rhombohedral phase and unusual transitions to a polaron-ordering state. As a result, the complete T-x phase diagram of the system La1−2x
Sr
x
MnO3 is constructed in a wide interval of temperatures T=4.2∓1050 K and concentrations x=0−0.45.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 331–336 (25 August 1998) 相似文献
2.
3.
4.
Garcia Ruano JL Alemparte C Martin Castro AM Adams H Rodriguez Ramos JH 《The Journal of organic chemistry》2000,65(23):7938-7943
The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles. 相似文献
5.
EI Rodriguez Martinez CI Barriga-Paulino MI Zapata CC Chinchilla AM López-Jiménez CM Gómez 《BMC neuroscience》2012,13(1):104-23
ABSTRACT: BACKGROUND: The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). RESULTS: The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0--20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. CONCLUSIONS: The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages. 相似文献
6.
7.
P. A. Usachev R. V. Pisarev A. M. Balbashov A. V. Kimel A. Kirilyuk Th. Rasing 《Physics of the Solid State》2005,47(12):2292-2298
Optical properties of the orthorhombic thulium orthoferrite TmFeO3 were studied in the spectral range from 0.64 to 5.4 eV. In the weak absorption region, below 2.2 eV, the energies of localized optical transitions in the Tm3+ and Fe3+ ions were determined. The dispersion relations of the real and imaginary parts of the principal refractive indices along three crystallographic axes were found. In the region of strong absorption, above 2.2 eV, the energies of six charge-transfer transitions were determined. The experimental data fit well to the concept of charge-transfer transitions in the FeO 6 9? octahedral complexes providing a dominant contribution to the optical properties of the orthoferrites. Optical birefringence and its temperature dependence were measured for the three principal directions of light propagation, and the anisotropic magnetic contribution to birefringence in the region of spin-orientational transitions was isolated. 相似文献
8.
Deisenhofer J Braak D Krug von Nidda HA Hemberger J Eremina RM Ivanshin VA Balbashov AM Jug G Loidl A Kimura T Tokura Y 《Physical review letters》2005,95(25):257202
We report on the discovery of a novel triangular phase regime in the system La1-xSrxMnO3 by means of electron spin resonance and magnetic susceptibility measurements. This phase is characterized by the coexistence of ferromagnetic entities within the globally paramagnetic phase far above the magnetic ordering temperature. The nature of this phase can be understood in terms of Griffiths singularities arising due to the presence of correlated quenched disorder in the orthorhombic phase. 相似文献
9.
Yu. F. Popov A. M. Kadomtseva G. P. Vorob’ev A. A. Mukhin V. Yu. Ivanov K. I. Kamilov Ya. S. Shtofich A. M. Balbashov 《Physics of the Solid State》2004,46(7):1252-1254
By studying the magnetic and magnetoelastic properties, it is established that, as the temperature is lowered, Sm1?xSrxMnO3 single crystals (x=0.5, 0.55) undergo spontaneous phase transitions from the paramagnetic to a local charge-ordered state at Tco=220 K and to an A-type antiferromagnetic state at TN=175 K. It is shown that strong magnetic fields (Hcr ~ 200 kOe) break up the antiferromagnetic order and charge ordering and drive a phase transition to a conducting ferromagnetic state. H-T phase diagrams are constructed for single crystals with x=0.5 and 0.55. 相似文献
10.
We propose a picture of Wigner function scars as a sequence of concentric rings along a two-dimensional surface inside a periodic orbit. This is verified for a two-dimensional plane that contains a classical hyperbolic orbit of a Hamiltonian system with 2 degrees of freedom. The stationary wave functions are the familiar mixture of scarred and random waves, but the spectral average of the Wigner functions in part of the plane is nearly that of a harmonic oscillator and individual states are also remarkably regular. These results are interpreted in terms of the semiclassical picture of chords and centers. 相似文献