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101.
102.
I. Stanojevi? D. Drakuli? N. Veli?kovi? M. Milo?evi? S. Petrovi? A. Horvat 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(9):1596-1601
Cell membrane is highly sensitive to irradiation which, acting directly or indirectly, may disturb functions of constitutive
proteins including membrane enzymes. Plasma membrane surface-located enzyme chain of ecto-nucleotide triphospho diphosphohydrolases
(NTPDases) and 5′-nucleotidase are involved in termination of cell purinergic signalization by hydrolyzing extracellular,
excitatory adenosine triphosphate (ATP), as well as nucleotide di-, and mono-phosphate (ADP and AMP) to neuroprotective adenosine.
Extracellular ATP, ADP, and AMP hydrolyzes were examined in purified synaptic plasma membranes after whole-body acute irradiation.
All measurements were done 24 h after irradiation of developing (15-, 30-day-old) and adult (90-day-old) rats with low (50
cGy) and high (2 Gy) dose of gamma-rays. Both, high and low doses inhibited nucleotide hydrolyses in 15-day-old rats; in 30-day-old
rats low dose of radiation inhibited ADP and AMP hydrolyses while high dose inhibited only ATP hydrolyse. In adult rats high
dose induced no effects, while low dose stimulated nucleotides hydrolyses. According to obtained results it was concluded
that ecto-nucleotidases of young rats are more sensitive to irradiation, since even low dose induces inhibition of ecto-nucleotidases
activities. Ionizing radiation, by decreasing brain nucleotide hydrolyses in developing rats, induces accumulation of ATP
and decreases production of adenosine in synaptic cleft which could be neurocytotoxic. On the contrary, in adult rats low
dose of radiation stimulates NTPDase and 5′-nucleotidase activity and protective adenosine production which indicates protective
and adaptive mechanisms developed in adult brain neuronal cells.
The article is published in the original. 相似文献
103.
Miloš Matyáš 《Czechoslovak Journal of Physics》1958,8(3):309-314
The results of measuring the temperature dependence of the susceptibility (T) of samples of PbSe, Sb2Se3, Sb2Te3, Bi2Se3
and Bi2Te3
are given and the measured curves explained. The connection between the molar susceptibility of the characteristic crystal lattice of these semiconductors and the total number of electrons in their molecules is pointed out. 相似文献
104.
Miloš Novák 《Czechoslovak Journal of Physics》1959,9(1):78-83
[1] t
B
, t
B
. , t
B
, . .
A note on the theory of the successive production of moving striations in the plasma of inert gases
Approximate expressions are derived on the basis of Pekárek's theoretical paper [1] for the period of the maximum tB of a wave packet produced by the passage of a wave of stratification before the aperture of a photomultiplier, and for its time width in the half-height tB. The relaxation time of a wave of stratification, following from the theory [1], can thus be calculated by means of the experimentally measured velocity of motion of the maximum of a wave packet u and its width tB. The calculation is supplemented by numerical data on the magnitude of errors committed by using approximate expressions.相似文献
105.
Starting from a suitable fixed point relation, a new family of iterative methods for the simultaneous inclusion of multiple complex zeros in circular complex arithmetic is constructed. The order of convergence of the basic family is four. Using Newtons and Halleys corrections, we obtain families with improved convergence. Faster convergence of accelerated methods is attained with only few additional numerical operations, which provides a high computational efficiency of these methods. Convergence analysis of the presented methods and numerical results are given.
AMS subject classification 65H05, 65G20, 30C15 相似文献
106.
E. Hasović A. Kramo D. B. Milošević 《The European physical journal. Special topics》2008,160(1):205-216
We analyze strong-laser-field induced above-threshold
ionization and above-threshold detachment processes within the
strong-field approximation. Energy and angular distribution of
photoelectrons are presented for two cases: (1) high-order
above-threshold ionization of electrons from neutral atoms by a
linearly polarized laser field and (2) above-threshold detachment of
electrons from negative ions by a bicircular laser field. In
particular, for the case (1) we compare the results obtained using a
long pulse with the flat-top spatial intensity distribution in the
laser focus with the results obtained using the Gaussian
distribution. We also analyze the intensity-dependent
resonant-like enhancements. We show that the position and shape of these enhancements strongly
depend on the atomic ground state parity. The bicircular field of
the case (2) consists of two counter-rotating circularly polarized
fields having the frequencies rω and sω with integer
r and s. The properties of the photoelectron spectra generated
by such bicircular field are illustrated using an
ω–4ω example. The spectra obtained are explained in
terms of the interference of partial detachment amplitudes which
correspond to different complex solutions of the saddle-point
equations. 相似文献
107.
We present a simple method to obtain reliable ground-state entropies of the q-state Potts antiferromagnet in an external magnetic field. As an example, the ground-state entropy for the triangular lattice is established for all q. In the particular case q = 2, our method gives results which coincide with the first-order approximation obtained by the corner transfer matrix method. 相似文献
108.
Milo ícha 《Czechoslovak Journal of Physics》1958,8(4):490
109.
Miloš Matyáš 《Czechoslovak Journal of Physics》1956,6(5):531-532
110.
Miloš Seidl 《Czechoslovak Journal of Physics》1959,9(6):721-735
The paper deals with the collective behaviour of electrons which rotate in a magnetic field used in a betatron. It is shown experimentally that there exists strong interaction between the electrons, which leads to the rapid formation of the equilibrium state with characteristic distribution of the charge density in the cross-section of the toroidal beam. The corresponding relaxation time is of the order of 1 sec. A statistical theory of the equilibrium beam is elaborated. Its main result is that the effective radius of the beam is a function of two parameters, one of which is proportional to the thermal energy of the electrons and the other to the perveance of the beam. The charge contained in a toroidal beam of given effective cross-section is equal to the product of the charge the beam would contain at zero temperature and a coefficient, which is a function of the temperature of the beam. Its value is unity at zero temperature and rapidly decreases with increasing temperature. The cause of cooling of the beam is shown.
Now Institute of Vacuum Electronics, Czechosl. Acad. Sci., Prague.
In conclusion the author thanks J. Luká and L. Hyttych for invaluable help in the experiments, A. Rajský for constructing the electronic apparatus and J. Sokol for preparing the miniature probe. 相似文献
, . , , . 1S. . , , — I/(E0/q)3/2 (I — , 0 — q ). , , , , , . . .
Now Institute of Vacuum Electronics, Czechosl. Acad. Sci., Prague.
In conclusion the author thanks J. Luká and L. Hyttych for invaluable help in the experiments, A. Rajský for constructing the electronic apparatus and J. Sokol for preparing the miniature probe. 相似文献