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181.
A. N. Antonov Chr V. Christov E. N. Nikolov I. Zh. Petkov A. D. Polozov A. M. Pushkash 《Zeitschrift für Physik A Hadrons and Nuclei》1990,336(3):333-337
Using a noneikonal expression for the two-body scattering amplitude, consistent with the proton-nucleon scattering data, the cross-section of the 1.04 GeV-proton elastic scattering on40Ca is calculated by the Glauber-Sitenko theoretical scheme in the framework of the coherent density fluctuation model (CDFM) as well as of the independent-particle model (IPM). It is shown that the use of the noneikonal amplitude in the CDFM calculation improves the agreement with the experimental data especially at larger scattering angles in contrast to the case of the independent-particle model. To that end a decisive role play the zero-motion flucton correlations taken into account in the CDFM. 相似文献
182.
G. Ahmed I. Petkov S. Gutzov 《Journal of inclusion phenomena and macrocyclic chemistry》2009,64(1-2):143-148
New optical materials containing coumarin (3-(3-(4-(dimethylamino)phenyl)propenoyl)-2H-chromen-2-one) in silica are reproducibly prepared by a sol–gel technique and characterized with UV/Vis and luminescence spectroscopy. The incorporation of the coumarin molecules in the silica gels is monitored with UV/Vis spectroscopy. The coumarin doped gels change their color with time which is attributed to a protonation of the dimethylamino group of the coumarin molecules during aging of the gels and is proved by UV/Vis spectroscopy. The process of protonation of the dimethylamino group is described as a second order reaction. The luminescence spectra of the coumarin doped gels at room temperature also are given. 相似文献
183.
Koleva BB Stoyanov S Kolev T Petkov I Spiteller M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1857-1864
Structure, magnetic and optical properties of tetraphenylborate salts of 2,5-[1-methyl-4-[2-(4-hydroxyphenyl)ethenyl]piridinium]-propane and butane are performed in gas and condense phase by means of solution and solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids in nematic liquid crystal suspension, UV-vis and fluorescence methods, HPLC tandem ESI mess spectrometry (MS/MS), (1)H, (13)C and (1)H-(1)H COSY NMR, TGV and DSC methods. Quantum chemical DFT calculations are used for performing of the structures, optical and nonlinear optical properties of the studied compounds. 相似文献
184.
Tonev D de Angelis G Petkov P Dewald A Brant S Frauendorf S Balabanski DL Pejovic P Bazzacco D Bednarczyk P Camera F Fitzler A Gadea A Lenzi S Lunardi S Marginean N Möller O Napoli DR Paleni A Petrache CM Prete G Zell KO Zhang YH Zhang JY Zhong Q Curien D 《Physical review letters》2006,96(5):052501
Exited states in 134Pr were populated in the fusion-evaporation reaction 119Sn(19F,4n)134Pr. Recoil distance Doppler-shift and Doppler-shift attenuation measurements using the Euroball spectrometer, in conjunction with the inner Bismuth Germanate ball and the Cologne plunger, were performed at beam energies of 87 MeV and 83 MeV, respectively. Reduced transition probabilities in 134Pr are compared to the predictions of the two quasiparticle + triaxial rotor and interacting boson fermion-fermion models. The experimental results do not support the presence of static chirality in 134Pr underlying the importance of shape fluctuations. Only within a dynamical context the presence of intrinsic chirality in 134Pr can be supported. 相似文献
185.
Christopher I. Petkov Christoph Kayser Mark Augath Nikos K. Logothetis 《Magnetic resonance imaging》2009
The noninvasive imaging of the monkey auditory system with functional magnetic resonance imaging (fMRI) can bridge the gap between electrophysiological studies in monkeys and imaging studies in humans. Some of the recent imaging of monkey auditory cortical and subcortical structures relies on a technique of “sparse imaging,” which was developed in human studies to sidestep the negative influence of scanner noise by adding periods of silence in between volume acquisition. Among the various aspects that have gone into the ongoing optimization of fMRI of the monkey auditory cortex, replacing the more common continuous-imaging paradigm with sparse imaging seemed to us to make the most obvious difference in the amount of activity that we could reliably obtain from awake or anesthetized animals. Here, we directly compare the sparse- and continuous-imaging paradigms in anesthetized animals. We document a strikingly greater auditory response with sparse imaging, both quantitatively and qualitatively, which includes a more expansive and robust tonotopic organization. There were instances where continuous imaging could better reveal organizational properties that sparse imaging missed, such as aspects of the hierarchical organization of auditory cortex. We consider the choice of imaging paradigm as a key component in optimizing the fMRI of the monkey auditory cortex. 相似文献
186.
Let \(V(t) = e^{tG_b},\, t \ge 0,\) be the semigroup generated by Maxwell’s equations in an exterior domain \(\Omega \subset {\mathbb R}^3\) with dissipative boundary condition \(E_{tan}- \gamma (x) (\nu \wedge B_{tan}) = 0, \gamma (x) > 0, \forall x \in \Gamma = \partial \Omega .\) We study the case when \(\Omega = \{x \in {\mathbb R}^3:\, |x| > 1\}\) and \(\gamma \ne 1\) is a constant. We establish a Weyl formula for the counting function of the negative real eigenvalues of \(G_b.\) 相似文献
187.
D. D. Dzhappuev V. V. Alekseenko V. I. Volchenko G. V. Volchenko Zh. Sh. Guliev E. V. Gulieva A. U. Kudzhaev Yu. N. Konovalov A. S. Lidvansky O. I. Mikhailova V. B. Petkov D. V. Smirnov V. I. Stepanov Yu. V. Sten’kin N. S. Khaerdinov 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(4):525-527
The state of the art and the project of modernization of the extensive-air-shower array Carpet-2 of the Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences are described. The modernized array will allow the performance of detailed study of variations in the cosmic ray intensity, the energy spectra and composition of primary cosmic rays in the energy range 1013–1016 eV, and the anisotropy of primary cosmic rays with energies above 1013 eV. 相似文献
188.
Vesselin Petkov 《Foundations of Physics》2007,37(10):1499-1502
Should physicists deal with the question of the reality of Minkowski space (or any relativistic spacetime)? It is argued that they should since this is a question about the dimensionality of the world at the macroscopic level and it is physics that should answer it. 相似文献
189.
Titanium-containing surface compounds have been obtained by the interaction of the silanol groups of Vulcasil with TiCl4 vapour. These substances have been used, in combination with organ-oaluminium and organo-magnesium compounds, for the polymerization of ethylene. The effects upon the catalyst activity of the reaction conditions (temperature, pressure, duration of polymerization), of the titanium amount on the Vulcasil surface and the Al:Ti and Mg:Ti ratios have been studied.The activity of the catalyst system has been shown to increase with increasing pressure up to 11 kg/cm2 and to attain its optimum value at 60°. Polymerization has been found to end 15–20 min after the introduction of the monomer. The highest yields of polymer are obtained at Mg:Ti and Al:Ti ratios of about 30.The amount of titanium on the Vulcasil surface depends on the conditions of preliminary heat-treatment of the Vulcasil and decreases from 0.63 to 0.30 mg at/g with increasing dehydroxylation temperature. Simultaneously, the yield of polymer varies within a narrow range (89–107 g/l), and the productivity increases from 21 to 35.5 kg polyethylene (PE) per 1 g of Ti. This is especially clearly expressed with the samples obtained by preliminary heat-treatment at 400–700°. 相似文献
190.
W. Andrejtscheff L. K. Kostov L. G. Kostova P. Petkov A. Dewald J. Eberth K. O. Zell P. von Brentano L. Funke E. Will 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(4):433-438
The half-life of a 3? excited state in106Ag was measured as T1/2 (364.4 keV)=0.9±0.1 ns using the103Rh(α, n)106Ag reaction. The intramultiplet transition rate B(M1, 3?→2?) indicates that the configuration π(g9/2)0 ?2π(p1/2)?1 vd5/2 can be assigned. A low-lying 3+ isomer, as known in108,110Ag, was not found in106Ag, what is explained by the raising energy of the vd3/2 shell with decreasing neutron number. For the 6? bandhead of a rotational-like structure T1/2 (765.2 keV)< 0.2 ns was derived in contradiction to an earlier prediction (200 ns). Indirect evidence for a negative sign of the magnetic moment of105Ag (g.s.) is obtained. 相似文献