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61.
Bei frühgeborenen S?uglingen spielt die Thermoregulation zur Aufrechterhaltung einer überlebenswichtigen K?rpertemperatur durch W?rmeproduktion, -abgabe bzw. -aufnahme eine entscheidende Rolle. Der Einsatz moderner Inkubatoren soll die k?rpereigenen Thermoregulatoren unterstützen, und es ist im Hinblick auf verschiedene medizinische Fragestellungen wünschenswert, diesen Prozess modellieren zu k?nnen. Wir stellen ein einfaches Modell auf der Basis von partiellen Differentialgleichungen vor und beschreiben detailliert die numerische Simulation mit Hilfe einer Finite-Volumen-Methode. Dazu wird ein zweidimensionales Modell eines Frühgeborenen trianguliert und das Modell diskretisiert. Zahlreiche numerische Resultate zeigen die Qualit?t unseres Modells. 相似文献
62.
63.
C. -V. Meister 《Radiophysics and Quantum Electronics》1996,39(1):64-74
A model of a Langevin equation for electrons in turbulent, almost collisionfree magnetoactive plasmas is developed, which can form the starting point for particle simulations, especially in regions with reconnection of magnetic-field lines. The mean wave force is expressed by a friction force and a velocity derivative of the intensity of the stochastic force. The obtained expression for the Langevin force is consistent with the kinetic theory in a polarization approximation. The intensity of the stochastic force corresponds to the velocity diffusion tensor of the electrons, which is estimated for plasmas with ionacoustic turbulence using two different methods. One method is based on direct calculation of the space-time spectral density of the wave energy. The second method uses approximations of quasi-linear plasma theory. The estimates for the intensities of the stochastic forces found by the two methods differ by orders. A table of parameters of ion-acoustic waves, electron-wave collision frequencies, and intensities of stochastic-wave forces on electrons in solar flares, in the solar wind, as well as in different regions of the earth's magnetosphere is presented. Results are given for the entire ranges of available experimental data for the mean magnetic induction, mean plasma temperatures, and mean particle densities.Published from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 1, pp. 93–107, January, 1996. 相似文献
64.
The dissolution of cellulose in different ionic liquids will be described as a very recent subject for a direct dissolving
process, which was used to prepare regenerated cellulose fibres. The preparation of the dopes was arranged starting from slurry
of cellulose in the aqueous ionic liquid by removing the water at elevated temperature, vacuum and high shearing rates. As
ionic liquids, the 1-N-Butyl-3-methylimidazolium chloride, the 1-Ethyl-3-methylimidazolium chloride, the 1-N-Butyl-2,3-dimethylimidazolium chloride, the 1-N-Butyl-3-methylimidazolium acetate and the 1-Ethyl-3-methylimidazolium acetate were investigated. The cellulose solutions
in ionic liquids were characterised by means of light microscopy, cone-plate rheometry and particle analysis. In addition
these results were compared with cellulose solutions in N-methyl-morpholine-N-oxide monohydrate. Finally the cellulose dopes were shaped by a dry-wet spinning process to manufacture cellulose fibres.
The properties of the resulted fibre had been determined and will be discussed. 相似文献
65.
Stable solutions of equations of the first kind and equations of the second kind at a characteristic value are given. Iterative processes for solutions are constructed. Extension of operators is used to turn an ill-posed problem into a well-posed one. 相似文献
66.
67.
Michel Dedieu Yves-Louis Pascal Pierre Dizabo Jean-Jacques Basselier 《Journal of mass spectrometry : JMS》1977,12(3):153-158
The mass spectra of the title compounds always show an intense molecular ion. Some fissions involve loss of the ethylenic group, while others are related to cleavage of the dithiane ring, eventually followed by recyclizations involving the ethylenic chain stabilized by the resonance possibilities. If a phenyl group is present in the ethylenic chain, the spectra are modified by the formation of the very stable benzothiopyrylium ion. 相似文献
68.
Jean-Jacques Vasseur Bernard Rayner Jean-Louis Imbach 《Journal of heterocyclic chemistry》1988,25(2):389-392
We have elucidated the exact mechanism of apurinic oligodeoxynucleotide d(Tp[AP]pT) cleavage by phenylhydrazine and shown that the final isolated product is in fact a 3-substituted derivative of 1-phenyl-pyrazole. 相似文献
69.
Odile Convert Catherine Deville Jean-Jacques Godfroid 《Magnetic resonance in chemistry : MRC》1977,10(1):220-223
The 13C n.m.r. spectrum of the bridge substituted dicoumarols are interpreted in order to obtain structural information for quantitative structure-activity relationships. The results are in agreement with those obtained by 1H n.m.r. These dicoumarols exhibit double restricted rotation around both bridge bonds. 相似文献
70.