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931.
932.
The radical anion of aceneazulenedione in which a benzoquinone is fused to an azulene moiety was generated by electrolysis and by reduction with the alkali metals in ethereal solvents. The hyperfine data could not be reproduced by standard Hückel calculations which usually give reliable predictions for the spin distribution in radical ions such as azulene quinones and a variety of extended π systems. However, PPP and, preferably,ab initio geometry optimisations followed by single-point calculations of the Fermi contact interaction with density functional theory, led to a straightforward assignment of the hyperfine coupling constants. 相似文献
933.
T. G. Kuznetsova K. G. Ione N. F. Salakhutdinov 《Reaction Kinetics and Catalysis Letters》1997,62(2):273-280
The interaction of α-methacrolein with mixedtrans- andcis-alloocimenes on β zeolite has been studied at room temperature in a solvent under various conditions. The scheme of the process
has been specified including the formation of (4+2) and (3+2)-cycloaddition products and strongly adsorbed alloocimene species. 相似文献
934.
G. F. Brand 《International Journal of Infrared and Millimeter Waves》1997,18(9):1655-1662
A millimeter-wave interferometer operating purely on the geometric phase is presented. Like its optical counterpart described
by Hariharan and Roy, this system uses two circular polarizers with a half-wave section in between. The geometric phase of
each signal is determined by the orientation of the half-wave section. 相似文献
935.
Magnetic-field-induced polymorphism of biperiodic stripe domain structures of films with a positive anisotropy constant and
easy axis parallel to the normal to the surface is studied. A symmetry classification of the observed types of domain structures
is performed, and the phase diagram of the films in the (H
⊥, H
∥) plane, where H
⊥ and H
∥ are, respectively, the components of the magnetic field vector perpendicular and parallel to the normal to the surface, is
determined.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 701–706 (10 May 1998) 相似文献
936.
We obtain an exact solution of the problem of the stress-strain state of an elastic piezoelectric half-space acted on by a
rigid elliptic die with a flat base. The axis of symmetry of the body coincides with the direction of the field of preliminary
polarization of the body. The solution is confined to the case of translational displacement of the die. We determine the
quantities that characterize the mechanical and electric fields that arise in the region of contact of the die with the half-space.
Bibliography: 7 titles.
Translated fromTeoreticheskaya i Prikladnaya Mekhanika, No. 28, 1998, pp. 40–52. 相似文献
937.
Yu. G. Abov D. S. Denisov N. O. Elyutin S. K. Matveev Yu. I. Smirnov A. O. Éidlin F. S. Dzheparov D. V. L’vov 《Journal of Experimental and Theoretical Physics》1998,87(6):1195-1200
The asymptotic behavior of the spectra for large values of the scattering vector for the case of elastic multiple small-angle
neutron scattering (SANS) is investigated theoretically and experimentally. An expansion of the spectrum in terms of the reciprocal
of the magnitude of the momentum transfer is obtained taking account of the influence of the instrumental line. It is shown
that, to within some factor, the leading term of the expansion is identical to the differential single-scattering cross section
averaged over a statistical ensemble of particles; several subsequent terms in the expansion are calculated and the range
of applicability of the resulting expressions is determined. The asymptotic behavior of the multiple SANS spectrum is measured,
using a two-crystal neutron spectrometer, for samples of an HTSC ceramic, the alloy Fe-Ni, and Al powder. The agreement between
the experimental results and the theoretical predictions is analyzed.
Zh. éksp. Teor. Fiz. 114, 2194–2203 (December 1998) 相似文献
938.
R. F. Bilyalov 《Russian Physics Journal》1998,41(11):1134-1138
A covariant spinor derivative is constructed in arbitrary reference frames and also in coordinates, with specified arbitrary
linear connectedness.
Kazan State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 78–83, November, 1998. 相似文献
939.
For a real Enriques surface Y we prove that every homology class in H1(Y (R), Z/2) can be represented by a real algebraic curve if and only if all connected components of Y(R) are orientable. Furthermore, we give a characterization of real Enriques surfaces which are Galois-Maximal and/or Z-Galois-Maximal and we determine the Brauer group of any real Enriques surface Y. 相似文献
940.
F. Schümann S. Zavatarelli L. Gialanella U. Greife M. Junker D. Rogalla C. Rolfs F. Strieder H.P. Trautvetter 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):337-342
Abstact: The elastic scattering cross sections, σ (E,θ), for the systems He+Ta and He+W have been measured at θlab=165° and E
lab=76.1 keV to 3.988 MeV using targets with a thickness of a few atomic layers. The results are smaller than the results given
by the Rutherford scattering law, σR(E,θ), due to the effects of electron screening and can be described by σ(E,θ)/σR(E,θ)=(1+Ue/E)−1, where U
e is an atomic screening potential energy. The deduced average value, U
e=28 ± 3 keV, is consistent with the Moliére- and Lenz-Jensen-models as well as electron binding energies.
Received: 25 May 1998 相似文献