全文获取类型
收费全文 | 44篇 |
免费 | 0篇 |
专业分类
化学 | 25篇 |
晶体学 | 1篇 |
数学 | 1篇 |
物理学 | 17篇 |
出版年
2013年 | 2篇 |
2011年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2002年 | 1篇 |
2001年 | 3篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 4篇 |
1971年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有44条查询结果,搜索用时 15 毫秒
1.
Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5×1013 and 7.5×1013 ions/cm2. The relative intensity ratios D 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy. 相似文献
2.
3.
The electronic absorption spectrum of thioformaldehyde has been recorded from 2200 to 1800 Å. Four electronic transitions have been identified in the spectrum and have been assigned to the π → π*, n → 4s, n → 4py and n → 4pz electron promotions. 相似文献
4.
Derivatives of N-acetylgalactosamine and N-acetylglucosamine in which the 4-OH group could be selectively labelled have been prepared from a common precursor. 相似文献
5.
The results of a vibrational and rotational analysis of the banded transition in are presented. Only three of the six vibrational modes are active in the spectrum with , , and . The spin forbidden transition gains intensity primarily by a mixing of the and states. This is confirmed by a rotational analysis of the 000 band of both isotopes. The rotational analysis shows that the coupling in the state is near Hund's case b and that the spin constants are nearly 10 times greater than those observed for CH2O. A calculation shows that this difference is due to the greater spin orbit coupling of S in CH2S and to the smaller energy differences between the , , , and the states. The r0 structure calculated from the rotational constants is , , βHCH = 119.6°, and α (out of plane) = 16.0°. A simultaneous fit of the vibrational levels in ν′4 of CH2S and CD2S to a double minimum potential function yielded a barrier to molecular inversion of 13 cm?1 and an equilibrium out-of-plane angle of 15°. 相似文献
6.
In subnormal glow discharge under d.c. excitation at different pressure in a varying transverse magnetic field (0 to 30 G)
some measurements have been carried out for various initial average tube currents. The voltage across the discharge increases
and average tube current and residual current decreases in the magnetic field. With the help of Beckman’s expression [4] for
the axial field and the electron density distribution in a transverse magnetic field the observed variation of current and
voltage can be satisfactorily explained. The variation of axial electric field with transverse magnetic field can be represented
to a fair degree of accuracy by the derived equation. The behaviour of residual current with magnetic field has been observed
in these oscillations. 相似文献
7.
The ultraviolet absorption spectrum of formyl chloride has been recorded under conditions of modest resolution, 0.75 nm/mm, and long pathlengths, 96 m. The 314- to 269-nm spectrum proved to have well-defined vibrational fine structure and was assigned to the electron promotion, . A comparison of the spectra of CHClO at 25 and ?78°C with CDClO led to the assignments: pseudo-origin, ν2, ν4, ν5, and ν6; , , , , and for , respectively. A fit of the 60, 62, 63, and 65 levels to those generated from a Gaussian-quadratic model potential yielded a barrier height of 1608.8 cm?1 and an out-of-plane angle of 48.6° for the state. 相似文献
8.
9.
The uniqueness of the general harmonic force field of methyl fluoride is analyzed. The analysis is applicable to other methyl halides as well. Through the compliance scheme, it is seen that by supplementing the data employed by Aldous and Mills (i.e., vibrational frequencies ωi, Coriolis coupling constants ζi and the centrifugal stretching constants DJ, DJK of CH3F and CD3F molecules), with the frequencies of A′ or A″ species of either CH2DF or CD2HF, the force field is uniquely determined. The addition of any other extra data including the 12CH3F13CH3F isotopic shifts only makes the determination of the force field parameters more precise. 相似文献
10.
In this work, a Hamiltonian formalism and a 6D vibrational calculation procedure is described and implemented, designed for the exploration of vibrational motion in ammonia (and any XH3 molecule). The 6D potential energy surface of ammonia was modelled in simple analytical form (including the inversion potential) at the planar, totally symmetric (D3h) reference configuration. Using the described method (which is an adaptation of the formalism, previously developed and applied to benzene), 6D calculations were carried out on the vibrational level system of ammonia 14NH3, at the lower levels of vibrational excitation. On the basis of the satisfactory agreement between the calculated and the experimentally measured vibrational frequencies, the values of some important harmonic and anharmonic force constants, characterizing the ammonia PES were determined. 相似文献