排序方式: 共有75条查询结果,搜索用时 14 毫秒
51.
H. A. Gharibyan G. M. Makaryan M. R. Hovhannisyan F. S. Kinoyan Zh. A. Chobanyan 《Russian Journal of General Chemistry》2014,84(3):457-464
Hydroalumination-iodination of alkyne-1,4-diols of different structure showed that with increasing number of substituents at the C-OH group the amount of β-iodo-substituted products with respect to this group increased. In the case of symmetric secondary 1,4-diols the reaction results in a 1: 1 mixture of stereoisomeric iodoalkenediols, and in the case of phenyl substituents the reaction proceeds regio- and stereoselectively to give an alkenediol iodine atom in the β-position to phenyl group. 相似文献
52.
L. A. Haroutiunyan K. G. Trouni G. M. Hovhannisyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2011,46(1):34-36
A new type of X-ray interferometer based on three multilevel zone plates with common lens axis is suggested. Like to well-known triple Laue-case X-ray interferometer this interferometer does not impose strict requirements on the spatial and time coherence of the incident wave and therefore can be used with laboratory X-ray sources. The interferometer has advantages in the area of phase-contrast X-ray imaging connected with the image magnification. 相似文献
53.
T.R. Hovhannisyan A.G. Markossian G.F. Mkrtchian 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):17-25
On the base of relativistic generalized eikonal approximation wave function the multiphoton cross-sections of a Dirac particle
bremsstrahlung on an arbitrary electrostatic potential and strong laser radiation field are presented. In the limit of the
Born approximation the ultimate analytical formulas for arbitrary polarization of electromagnetic wave have been obtained
and numerically analyzed.
Received 5 April 2001 / Received in final form 18 March 2002 Published online 28 June 2002 相似文献
54.
A. R. Balabekyan A. S. Danagulyan J. R. Drnoyan G. H. Hovhannisyan N. A. Demekhina J. Adam V. G. Kalinnikov M. I. Krivopustov V. S. Pronskikh V. I. Stegailov A. A. Solnyshkin P. Chaloun V. M. Tsoupko-Sitnikov S. G. Mashnik K. K. Gudima 《Physics of Atomic Nuclei》2007,70(11):1889-1897
The recoil properties of the product nuclei from the interaction of 3.65-GeV/nucleon protons and deuterons from the Nuclotron
and Synchrophasotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna, with
a 118Sn target have been studied using catcher foils. The experimental data were analyzed using the mathematical formalism of the
standard two-step vector model. The analysis of kinematical characteristics of the light and medium-mass reaction products
confirmed the contribution of fragmentation (or multifragmentation) processes in the production of these nuclei. The comparison
of the results for protons and deuterons was made. The longitudinal momenta transferred to the target in the interaction with
protons and deuterons were similar and was shown to depend only on the velocity, but not on the mass of projectile. Three
different Los Alamos versions of the quark—gluon-string model (LAQGSM) were used for the discussion of our experimental results.
The text was submitted by the authors in English. 相似文献
55.
A. A. Hovhannisyan H. S. Minasyan O. V. Kovalchukova T. S. Kurtikyan 《Russian Chemical Bulletin》2018,67(7):1241-1246
It is revealed by FTIR and electron absorption spectroscopy that the reactions of dimethyl sulfoxide with the nitro complexes of Co-porphyrins both in the solid phase and an inert solvent afford six-coordinate complexes with the general formula (DMSO)Со(Por)(NO2) (Por is meso-tetraphenyl- and meso-tetra-p-tolylporphyrinato dianions). These compounds are stable in the solid state, whereas they partially decompose in an inert solvent to form five- and six-coordinate complexes. The ambident nitrite and dimethyl sulfoxide ligands are coordinated to the metal atom through the N and O atoms, respectively, which was confirmed by the application of isotope-containing compounds 15NO2 and DMSO-d6. 相似文献
56.
A. S. Danagulyan G. H. Hovhannisyan T. M. Bakhshiyan I. A. Kerobyan 《Physics of Atomic Nuclei》2016,79(5):679-685
Values of the isomeric ratios for product nuclei originating from simple charge-exchange reactions were analyzed. The cross sections for the formation of product nuclei in ground and isomeric states were calculated with the aid of the TALYS 1.4 and EMPIRE 3.2 codes. The calculated values of the isomeric ratios were compared with their experimental counterparts taken from the EXFOR database. For the 86,87Y, 94,95,96,99Tc, and 44Sc nuclei, the experimental values of the isomeric ratios exceed the respective calculated values. The nuclei in question feature weak deformations and have high-spin yrast lines and rotational bands. The possible reason behind the discrepancy between theoretical and experimental isomeric ratios is that the decay of yrast states leads with a high probability to the formation of isomeric states of detected product nuclei. 相似文献
57.
D. L. Hovhannisyan A. H. Vardanyan G. D. Hovhannisyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2017,52(4):335-347
The results of theoretical research and numerical simulation of the difference frequency radiation (DFR) pulse generation in 5–25 μm wavelength range in the field of the pumping femtosecond laser pulse are presented. The pulse has the following characteristics: the central wavelength is 2 μm, duration is 34 fs and electric field amplitude is 70.71 MV/m. The pulse propagates in the ZnTe/air periodic structure with the number of periods along the normal to the (110) plane of the ZnTe crystal equal to 13; and the efficiency of the DFR generation is 1.11 × 10–4. It is shown that the use of the liquid crystal phase transparent, placed in the focal plane of the frequencyspatial shaping system, allows one to realize the DFR pulse compression at which the maximum intensity is increased by a factor of six. 相似文献
58.
K. T. Avetyan L. V. Levonyan M. M. Arakelyan H. S. Semerjian P. A. Grigoryan G. M. Hovhannisyan 《Crystallography Reports》2009,54(3):386-390
A method for identifying lines in a diffraction image formed by a widely divergent X-ray beam and a technique for measuring the crystal structure parameters in the case of asymmetric crystal position have been developed. It is established that, once the distances between a crystal and a photographic plate and between the points of intersection of the hyperbola branches in a diffraction image are known, one can determine the angle between the crystal’s zone axis and the wave vector, which leads to multiwave diffraction. Relations linking this angle with the parameters of two atomic planes are obtained. It is found that, to measure the parameters of atomic planes belonging to a given zone, one can use different sets of crossed hyperbolas formed by radiations K α and K β. The measurements and calculations performed for the same sample (Si crystal), mounted symmetrically and asymmetrically, confirm the reliability of the proposed method. 相似文献
59.
D. L. Hovhannisyan A. H. Hovhannisyan G. D. Hovhannisyan K. A. Hovhannisyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2010,45(6):251-257
We consider the effect of Raman inertial response of a medium on the stability of a first-order femtosecond soliton. Numerical solution to the high-order nonlinear Schrödinger equation, with the complex Raman term, describing propagation of a femtosecond optical soliton in a single-mode fiber, is obtained. It is shown that a soliton solution of the high-order nonlinear Schrödinger equation exists under certain conditions imposed on the equation coefficients. These conditions lead to limitations on the wavelength, fiber type, and the highest energy. Results of numerical solutions are in agreement with available experimental data. 相似文献
60.
D. L. Hovhannisyan V. O. Chaltykyan A. S. Martirosyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2009,44(2):63-69
We present the results of theoretical studies of the process of generation of terahertz radiation arising via interaction of few-cycle laser pulses propagating in an isotropic nonlinear medium. Numerical time-integration, by the finite-difference method, of the system of nonlinear Maxwell equations has been performed. We consider the interaction of mutually-orthogonal linearly polarized pulses, both having the central wavelength of 1.98 μm, durations of 30 fs, and the energies of 30 nJ, propagating along the normal to the 〈110〉 plane in a 1 mm-thickness GaAs crystal. In the nonlinear part of the medium polarization the without-inertia nonlinear second-order susceptibility is taken into account. The process of formation of a terahertz pulse arising via spectral filtration of supercontinuum formed in the spectra of pump pulses at the output of nonlinear crystal is studied. The dependences of both the current frequency of the pump pulses on time for different lengths of nonlinear crystal and of pump pulse durations on the crystal length are obtained. Also the dependences of the current frequency of the terahertz pulse on time at different crystal lengths, as well as of the efficiency of generation of terahertz radiation on the length of nonlinear crystal and on the energy of pump pulses are obtained. 相似文献