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41.
A. V. Gaponov-Grekhov M. D. Tokman 《Journal of Experimental and Theoretical Physics》1997,85(4):640-649
We find classical analogs of quantum systems capable of stimulated emission of radiation in the absence of inversion. We show
that cyclotron parametric instability in low-frequency modulation of the distribution function of resonant particles can amplify
a bichromatic high-frequency field when amplification of each spectral component separately is impossible. We point to similar
modes for a Cherenkov resonance and a model system with lumped parameters. Finally, we suggest using this effect for converting
microwave radiation to a higher frequency.
Zh. éksp. Teor. Fiz. 112, 1176–1196 (October 1997) 相似文献
42.
A linear accelerated electron beam is a powerful source of highly energetic photons that can be used for various nuclear applications. In this work, the bremsstrahlung photon yields from thin targets such as Ta, Nb, Cu and Al have been calculated using the FLUKA simulation code. The simulation calculations were performed for incident electrons with energies in the range of 10–40 MeV and targets with thicknesses between 4×10?4 and 10?3 radiation lengths. 相似文献
43.
I. D. Tokman A. V. Shvetsov 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(1):97-104
The interrelation between the Faraday and the inverse Faraday
effects when the magneto-dipole interaction of a sample with an
electromagnetic wave is essential has been phenomenologically
investigated. This investigation was carried out in the spirit of
well-known Pitaevsky’s approach. The terahertz inverse Faraday effect
in single molecule magnets has been theoretically studied, the
conditions favorable for observing this effect have been
formulated. 相似文献
44.
Derek G. Gray Morag Weller Nilgun Ulkem Agnès Lejeune 《Cellulose (London, England)》2010,17(1):117-124
The surface compositions of lignocellulosic materials are critical to their end use performance. X-ray photoelectron spectroscopy
(XPS) measures the elemental composition sampling of a very thin surface layer, and has long been used to assess the surface
composition of dry lignocellulosic materials. The method is based on the quantification of carbon and oxygen XPS peak sizes
and shapes, but care is necessary to minimize the effects of surface contamination and degradation. We review the XPS method,
and present a simplified approach to estimate the surface lignin content of extractive-free samples. The approach corrects
for surface contamination and degradation by measuring the XPS signal of a cellulose standard under the same conditions as
the lignin-containing samples. The method is illustrated using XPS results for a series of extracted softwood kraft pulps. 相似文献
45.
46.
A linear theory of the cyclotron parametric instability in systems which are classical analogues of quantum lasers without inversion is developed. The cyclotron interaction of different types of modulated electron beams with a bichromatic field, produced by waves propagating at an angle with respect to a constant magnetic field, is investigated. It is shown that simultaneous amplification of two parametrically coupled modes with different frequencies and positive energy is possible in this system with modulation of the active and reactive components of the susceptibility of an electronic ensemble. The results obtained are important from the standpoint of the general theory of radiation processes in electron beams and plasma and for the advancement of microwave electronics. 相似文献
47.
In this article, N‐(2‐aminophenyl)arylsulfonamides (1–5) were successfully synthesized by the reaction of o‐phenylenediamine and various benzenesulfonyl chlorides. The Schiff base derivatives (1a–f; 4e) of those compounds were obtained using different aldehydes. Then, a series of neutral‐four coordinate Pd(II) complexes (6–10) were prepared from the reaction of Pd(OAc)2 and 1–5. On the other hand, when we tried to synthesize Pd(II) complexes containing Schiff base/sulfonamide ligands, two different situations were observed. Generally, when an electron‐donating group was attached to the imine fragment (1a–d) except for 1f, the Schiff base hydrolyzed and 6 was isolated. When an electron‐withdrawing group was attached to the imine fragment (1e, 4e), neutral four‐coordinate Pd(II) complexes (11–13) bearing Schiff base/sulfonamide ligands were isolated. The synthesized compounds were characterized by FT‐IR, elemental analysis and NMR spectroscopy. The complexes were used as a catalyst in the oxidation reaction of benzyl alcohol to benzaldehyde in the presence of H5IO6 in acetonitrile. All complexes showed satisfactory catalytic activity. The highest catalytic activity was obtained with 9. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
48.
G. M. Genkin Yu. N. Nozdrin A. V. Okomel’kov I. D. Tokman 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(1):60-62
A photomagnetization effect is observed for a (Tm,Bi)3(Fe,Ga)5O12 garnet film at T = 300 K due to the restructurization of its multidomain structure. Photomagnetization (ΔM) emerges under the action of circularly polarized laser radiation in the spectral range of 450–600 nm at lasing power P < 600 kW/cm2 and pulse duration τ i ~ 7ns. The dependences of ΔM are measured on the polarization of light and magnetic field, the latter being perpendicular to the surface of the film. The maximum value of ΔM is observed for the circular polarization of light without a magnetic field. Moreover, ΔM changes sign with as the circular polarization changes sign and is zero for linear polarization. 相似文献
49.
Lindroth E Danared H Glans P Pesić Z Tokman M Vikor G Schuch R 《Physical review letters》2001,86(22):5027-5030
In an electron-ion recombination study with Pb53+ dielectronic recombination resonances are found for as low as approximately 10(-3)-10(-4) eV relative energy. The resonances have been calculated by relativistic many-body perturbation theory and through comparison with experiment the Pb53+(4p(1/2)-4s(1/2)) energy splitting of approximately 118 eV is determined with an accuracy comparable to the position of the first few resonances, i.e., approximately 10(-3) eV. Such a precision provides a test of QED in a many-body environment at a level which can still not be reached in calculations. 相似文献
50.
We develop a classical model of the recently popular parametric effect of electromagnetically induced transparency (EIT), i.e., the formation of a “transparency window” inside a resonance absorption line of a three-level quantum system, which is accompanied by a record strong slowing of the probe wave. Based on this model, we consider the EIT effect for electromagnetic waves at frequencies of the electron-cyclotron resonance in a cold plasma. The parametric (three-wave) interaction of two electromagnetic modes (the frequency of one of these modes is equal to the electron gyrofrequency) with the electrostatic mode is considered. It is shown that the resonance growth in the electron oscillations at the gyrofrequency can be damped due to the parametric coupling with the collective electrostatic oscillations. Similar to analogous quantum systems, the group slowing of the probe electron-cyclotron wave in the transparency window takes place in the case considered. 相似文献