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101.
102.
Thomas Brand Markus Kunze Guido Schneider Thorsten Seelbach 《Archive for Rational Mechanics and Analysis》2004,171(2):263-296
We consider solutions bifurcating from a spatially homogeneous equilibrium under the assumption that the associated linearization possesses a continuous spectrum up to the imaginary axis, for all values of the bifurcation parameter, and that a pair of imaginary eigenvalues crosses the imaginary axis. For a reaction-diffusion-convection system we investigate the nonlinear stability of the trivial solution with respect to spatially localized perturbations, prove the occurrence of a Hopf bifurcation and the nonlinear stability of the bifurcating time-periodic solutions, again with respect to spatially localized perturbations. 相似文献
103.
Uwe Müller Annett Kunze Christian Decker Christian Herzig Johann Weis 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1515-1533
Abstract The photoinduced cationic crosslinking of α, ω-terminated disiloxanes (epoxy, vinyl ether, propenyl ether) has been investigated by means of Real-Time IR spectroscopy. A lipophilic iodonium salt and three lipophilic sulfonium salts were used as photoinitiator. The crosslinking rate is influenced by the type of α, ω-terminated disiloxane used and differed by a factor of more than 100 from the aliphatic epoxy to the vinyl ether derivatives. Moreover, the sulfonium salts were found to have a lower initiation efficiency than the lipophilic iodonium salt in the various systems studied. These results are in good agreement with the quantum yield of proton formation in a hexamethyldisiloxane/dimethoxyethane mixture. The final degree of conversion is larger with the ene derivatives than with the epoxy derivatives. The application of a kinetic method allows us to estimate the rate constant of the termination step (kt and for the propenyl derivative the rate constant of the propagation step kp. The termination step can be described by means of a first order reaction. kt was found to depend on the light intensity and the type of initiators used, whereas kp is independent of the initiator used. 相似文献
104.
H?kan Andréasson Markus Kunze Gerhard Rein 《Communications in Mathematical Physics》2011,308(1):23-47
We prove the existence of static, asymptotically flat non-vacuum spacetimes with axial symmetry where the matter is modeled
as a collisionless gas. The axially symmetric solutions of the resulting Einstein-Vlasov system are obtained via the implicit
function theorem by perturbing off a suitable spherically symmetric steady state of the Vlasov-Poisson system. 相似文献
105.
J. Kunze M. A. Wimmer S. Koelling E. Schneider 《Analytical and bioanalytical chemistry》1998,361(5):496-499
A ‘one bottle’ method to determine particulate debris of titanium and zirconium in blood serum was developed. Inductively coupled plasma – optical emission spectrometry (ICP-OES) was used to simultaneously detect both elements at concentrations above 50 ng/mL. Pressurized digestion by means of nitric and hydrofluoric acid in PTFETM-containers in a specific time-heat-pressure protocol apparatus was applied to assure complete solvation of particles including oxides. Total decomposition of the matrix was achieved and reasonable detection limits were accomplished. The amount of remaining carbon did not cause any matrix problems during measurement. 相似文献
106.
107.
V. Kunze W. -D. Schmidt-Ott H. Behrens 《Zeitschrift für Physik A Hadrons and Nuclei》1990,337(2):169-173
In the decay of22Na theEC/β + ratio for theβ-transition to the 1275 keV-level was measured to beEC/β +=0.1050 (29). Single and coincidence counting was performed using a 16% Ge(Li) and an NaI well-type detector. For65Zn theK/β + ratio for the ground state transitionK 1/β +=30.3 (10) was obtained using the same apparatus and in addition a 10 mm diam. × 5.4 mm Si(Li) detector. The results are compared with earlier experiments and with theory. 相似文献
108.
Rare earth element substituted bismuth ferrites (BiFeO3) are of enormous importance as magnetoelectric materials. The polycrystalline samples of Bi
x
La1−x
FeO3 (x=0, 0.2, 0.4, 0.6, 0.8) were prepared by solid-state reaction using standard ceramic method. The single-phase formation of
these compounds was confirmed by X-ray diffraction (XRD) studies. The samples with x=0, 0.2, 0.4, 0.6 are found to be orthorhombic while the sample with x=0.8 is triclinic. The dielectric constant (ε′) and dissipation factor (tan δ) were measured in the frequency range 100 Hz
to 1 MHz at room temperature and as a function of temperature at certain fixed frequencies (1 kHz, 10 kHz, 100 kHz, 1 MHz).
All the samples showed dielectric dispersion. The dielectric constant with temperature shows a broad peak; the peak temperature
shifts with frequency which reflects the relaxor-type behavior. The peak above 600 K in the measured temperature range corresponds
to antiferromagnetic ordering temperature (Néel temperature). The broadness of the peak changes with composition. The ac conductivity
as well as ε′ are found to be maximum for the sample x=0.2 at room temperature. 相似文献
109.
CoFe2O4-BaTiO3 composites were prepared using conventional ceramic double sintering process with various compositions. Presence of two phases
in the composites was confirmed using X-ray diffraction. The dc resistivity and thermoemf as a function of temperature in
the temperature range 300 K to 600 K were measured. Variation of dielectric constant (ɛ′) with frequency in the range 100 Hz to 1 MHz and also with temperature at a fixed frequency of 1 kHz was studied. The ac
conductivity was derived from dielectric constant (ɛ′) and loss tangent (tan δ). The nature of conduction is discussed on the basis of small polaron hopping model. The static value of magnetoelectric
conversion factor has been studied as a function of magnetic field. 相似文献
110.
Heavy metals exist in natural waters in different species. Mobility and bioavailability of bound metals can be influenced by some complex factors in the aquatic environment. Therefore, it is useful to determine the complexation properties of various ligands influenced by different metals. The copper and zinc complexation capacity was determined for a natural ligand (fulvic acid) and anthropogenic pollutants (e.g. nitrilotriacetic acid and ethylenediaminetetraacetic acid). The interactions between several ligands and metal ions and their effects on the complexation capacity were analyzed in particular. Applying methods of experimental design, such as multifactorial plans, it is possible to determine influence and interaction of various parameters (e.g. concentration of zinc or copper) by a minimum number of experiments. Differential pulse polarography was used for the determination of the complexation capacity. Methods of parametric and robust multiple linear regressions were applied for the interpretation of the measured values. 相似文献