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1.
V. V. Nikitenko A. I. Martynenko S. A. Ostrovsky V. V. Rusak V. V. Kryuchkov D. A. Topchiev 《Russian Chemical Bulletin》1993,42(2):378-380
3-Methyl-l-vinylpyrazole (M3VP) and 5-methyl-1-vinylpyrazole (M5VP) were isolated as individual substances by vacuum rectification of their mixture (M3VP: M5VP 60 40). For each of them the kinetics of free-radical polymerization in MeOH were measured at low conversions. In both cases the rate of polymerization is proportional to 0.5 order with respect to the initiator (AIBN) concentration. On the other hand, a first order of reaction with respect to monomer concentration is observed only when the latter is relatively low (3M). At higher initial concentrations of monomers the order of reaction becomes less than unity. The overall rate of polymerization for M5VP was higher than for M3VP, whereas the initiation rate remained constant in the whole range of monomer concentrations and did not depend on the exact structure of the monomer. The difference in the rates of polymerization observed for M3VP and M5VP is probably connected with the difference in the key parameterk
p/k
t
1/2
for each of the two isomers. It is concluded that the correct kinetic information about homo- and co-polymerization of M3VP and M5VP cannot be obtained without their adequate separation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 413–415, February, 1993. 相似文献
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In the space $C(\mathbb{R})$ , we construct special summation operators of Jackson type with rational kernels and under a suitable choice of poles we obtain order estimates for deviations of these operators from functions belonging to certain classes. 相似文献
3.
Numerical-Asymptotic Expansion Matching for Computing a Viscous Flow Around a Sharp Expansion Corner
A computational technique which is based on a numerical-asymptotic expansion matching for computing the local singular behavior
of a viscous flow around a sharp right-angle expansion corner is presented. Moffatt's (1964) asymptotic solution is extended
and a matching with a time-marching finite-difference scheme of the Navier--Stokes equations is formulated. Local mesh refinement
around the corner is required to meet the validity of the asymptotic solution. Flows in an expanding channel with expansion
ratio D/d=3 at various Reynolds numbers 1≤Re≤700 are simulated. The results are compared with those from a standard finite-difference scheme that uses second-order forward/backward
differences near the corner. It is found that the results of the standard scheme converge toward those of the present technique
as the level of local refinement near the corner is increased. The time-dependent parameters of the first two terms of the
asymptotic solution at the steady-state solution are also described for various cases of Re and D/d. It is demonstrated that the present method enhances the accuracy of the simulations and requires less refinements near the
corners to achieve converged numerical results.
Received 14 August 2000 and accepted 25 October 2001 相似文献
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V. N. Rusak 《Mathematical Notes》1973,13(4):299-302
We investigate some regular rational functions on the real axis, with fixed poles, conjugate in pairs, of half-integer order. An extremal equality is obtained, which generalizes one of L. V. Taikov's results for trigonometric polynomials.Translated from Matematicheskie Zametki, Vol. 13, No. 4, pp. 493–498, April, 1973. 相似文献
6.
I. V. Bodnar V. F. Gremenok O. N. Obraztsova L. V. Rusak V. Yu. Rud' Yu. V. Rud' 《Journal of Applied Spectroscopy》1999,66(1):151-153
Based on single crystals of AgGaSe2, AgGaTe2, CuGaTe2 of the p-type, surface-barrier structures were manufactured by vacuum thermal deposition on illumination of which the photovoltaic
effect was observed. It is established that the longwave edge of the photosensitivity of such structures possesses several
inflections attributable to photoactive absorption involving paracipation of levels of lattice defects. It is shown that In/p-(Cu,
Ag)Ga(Se, Te)2 surface-barrier structures can be used as wide-band transducers and photoanalyzers of linearily polarized radiation.
Translated from Zhurrnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 141–144, January–February, 1999. 相似文献
7.
Condensation of cyclohexanone with acetonitrile on zeolites with different carcass structures was studied. The highest yield of cyclohexylideneacetonitrile (80 wt %) at a 98% selectivity of the process was attained with NaX zeolite containing 0.5 wt % KOH. Factors responsible for different catalytic activities and selectivities of zeolites are discussed. 相似文献
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