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41.
Studying the kinetics of isothermal decomposition
of thirteen selenites at isothermal heating, the values of activation energy E of the process, pre-exponential factor A in Arrhenius equation and changes of entropy for
the formation of the activated complex of the reagent were calculated. Direct
dependence between the thermal stability of the selenites and their cation
radii on their 'hardness' or 'softness' was found.
The dependence was interpreted in the terms of the generalized perturbation
theory of chemical reactivity. Kinetic compensation effect was observed only
for the selenites, which thermally decompose by the same mechanism. 相似文献
42.
MK Bhide RM Kadam MD Sastry Ajay Singh Shashwati Sen Manmeet Kaur DK Aswal SK Gupta VC Sahni 《Pramana》2002,58(5-6):799-802
Microwave absorption studies have been carried out on MgB2 superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for
polycrystalline (grain size ∼ 10 μm) samples suggested the absence of weak-link character. The field dependent direct microwave
absorption has been found to obey a ✓H dependence with two different slopes, which indicated a transition from strongly pinned lattice to flux flow regime. 相似文献
43.
S. D. Odintsov G. S. Ivanov-Kholodnyi K. Georgieva 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(4):593-595
Results of studying the character and possible succession of cause-effect relations (in going from a disturbance source on the Sun to a response in the lithosphere in the range of periods from several days to the 11-year solar cycle) have been presented. It has been indicated that the maximum of seismic energy, released from earthquake sources in the 11-yr cycle of sunspots, is observed during the phase of cycle decline and lags 2 yr behind the solar cycle maximum. It has been established that the maximum in the number of earthquakes directly correlates with the instant of a sudden increase in the solar wind velocity. 相似文献
44.
The nanocrystal thin films of zinc oxide doped by Al (ZnO:Al) were deposited by dc reactive magnetron sputtering on the glass substrates, in the pressure range of 33-51 Pa. From the X-ray diffraction patterns, the nanocrystalline structure of ZnO:Al films and the grain size were determined. The optical transmission spectra depend from the sputtering pressure, but their average value was 90% in the range from 33 Pa to 47 Pa. Also, the sputtering pressure changes the optical band gap of ZnO:Al films, which is highest for films deposited at 37 Pa, 40 Pa and 47 Pa. The obtained films at room temperature have a sheet resistance of 190 Ω/cm2 which increases with time, but the films annealed at temperature of 400 °C have constant resistance. The surface morphology of the films was studied by Scanning electron microscopy. XPS spectra showed that the peak of O1s of the as-deposited films is smaller than the peak of the annealed ZnO:Al films. 相似文献
45.
St. Christoskova M. Stojanova M. Georgieva 《Reaction Kinetics and Catalysis Letters》1999,67(1):59-66
The low-temperature oxidation of cyanide ions to CO2 and N2 in an aqueous phase in the presence of Ni-oxide system has been studied. The effect of pH, temperature and catalyst amount
on the rate and selectivity of the oxidation process have been investigated. A kinetic model of the reaction studied is proposed
based on the experimental results. It can be used to develop a catalytic method for purification of CN containing wastewaters. 相似文献
46.
Expressions for q-similarity transformations with respect to the symmetric q-exponentials are investigated. It is found that a series in multiple q-commutators can be formulated. The values of the qs in the different q-commutators are obtained by solving systems of algebraic equations. 相似文献
47.
Infrared and Raman spectra of 1,1-(methylphosphinylidene) bis(methanamine) [mpbm, (CH3)PO(CH2NH2)2] and its N,N′-coordinated Pt(II) and Pd(II) have been studied in the 4000–200 cm−1 frequency range. Ab initio calculations have been carried out for different conformations of the mpbm at HF/6-31G* level of the theory from which structural parameters, conformational stability and predicted infrared and Raman spectra have been obtained. A complete vibrational assignment of the lowest energy conformer, tttg−, as well as of its N,N′-coordinated Pt(II) and Pd(II) chloro-complexes was done on the basis of the calculated frequencies, relative infrared intensities, Raman activities and potential energy distribution (PED). The theoretical predictions are compared with the experimental results where appropriate. 相似文献
48.
The symmetric sinc-Galerkin method developed by Lund, when appliedto the second-order self-adjoint boundary value problem, givesrise to a symmetric coefficient matrix has a special structureso that it can be advantageously used in solving the discretesystem. In this paper, we employ the preconditioned conjugategradient method with banded matrices as preconditioners. Weprove that the condition number of the preconditioned matrixis uniformly bounded by a constant independent of the size ofthe matrix. In particular, we show that the solution of an n-by-ndiscrete symmetric sinc-Galerkin system can be obtained in O(nlog n) operations. We also extend our method to the self-adjointelliptic partial differential equation. Numerical results aregiven to illustrate the effectiveness of our fast iterativesolvers. 相似文献
49.
50.