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The convergence of the eigenchannel (EK) and R-matrix (RM) theories - depending on their free parameters - is numerically investigated by comparing with a simple, analytically solvable model. The comparison shows that the results of the EK-theory are in general closer to the exact solution than those of the RM-theory. Especially in regions of sharp resonances the dependence of the expansion of the wave functions on the interaction radius ac and on the boundary condition Bc is very strong in the RM-theory and one needs very many levels to achieve good results.
The association of Schlen k’s hydrocarbon was studied by means of osmometric and magnetic measurements. The mixed chain-ring-association can be explained satisfactorily assuming that two different dimers and four monomer species participate in the equilibria, including a monomeric diamagnetic ring. The equilibria existing between the different species are discussed. For the equilibria between the monomer and dimer species, which can be detected in solutions of normal viscosity by means of ESR-measurements, the unexpected values of ΔH=0 for the enthalpie of association and ΔS= +19.7 e. u. for the entropie of association were found.
Substituted amides react with tridiloromethanesulfenyl chloride in the presence of triethylamine to following compounds: S=PCl2NCH3SCCl3, S=PFCl2NCH3SCCl3, S =PFClNCH3SCCl3, S=PF2NCH3SCCl3, O = PCl2NCH3SCCl3, O= PFClNCH3SCCl3, O = PF2NCH3SCCl3, FSO2NCH3SCCl3 and CF3SO2-NCH3SCCl3. The properties of these substances are described. They were characteriszed by elemental analyses, IR- and mass spectra. 19F-, 1H- and 31P-NMR spectra are reported and discussed.
By reacting S = PX2NHCH3 or O = PX2NHCH3 (X = F and/or Cl) with S = PF2Br in the presence of triethylamine the following compounds are prepared: S = PCl2NCH3F2P = S, S = PFClNCH3F2P = S, O = PCl2NCH3F2P = S and O = PFClNCH3F2P = S. Also, the infrared, proton NMR, fluorine NMR, phosphorus NMR, and mass spectral data of these compounds are presented and discussed.
The preparations of the following compounds are described: O = PF2N = PCl2N = PCl3, O = PF2N = PCl2N = PCl2N (CH3) 2, O = PF2N=PCl2N = PCl2N (C2H5) 2, O = PF2N = PCl2N (CH3) 2, O = PF2N = PCl2N (C2H5)2, O = PF2N = PCl2N (CH3) Si (CH3)3, O = PF2N = PCl2NCS, O = PFClN = PCl2N (CH3)2, O = PFClN = PCl2N (C2H5)2, O = PFClN = PCl [N (C2H5)2]2 and O =P (C6H5) FN = PCl3. They were characterized by 1H-, 19F- and 31P-nmr spectroscopy. Analytical, ir and mass spectral data are reported. The properties of these substances are compared with the corresponding thiophosphorylderivatives.
Gel layers of crosslinked polyacrylamide with different porosities were synthesized and their properties compared. At high concentrations of bifunctional monomers macroporous gels were formed, one of which (total monomer concentration 14%, methylene-bis-acrylamide 40%) permitted even high molecular weight proteins (e. g. γ-globulins) to diffuse more readily than in 2 per cent agar or agarose gels. Different immunological techniques were modified for application with this polymer. It offers advantages especially with respect to porosity, storability and sample application for quantitative diffusion techniques.
The ion-molecule reactions of thiothionylfluoride have been studied by ion cyclotron resonance spectrometry. The major secondary ions are S2F3+ , S3F+ , and S3F2+. In a consecutive reaction of S3F2+ the tertiary ion S4F2+ is formed. The rate constant of the IMR with the greatest yield S2F2+ + SSF2 → S3F2+ + SF was estimated to k = 2 · 10-9 cm 3 molecule -1 sec -1 . The results were compared with the mass spectrum of thiothionylfluoride. They permit conclusions on chemical reactions of lower sulphurfluorides.
A thermodynamic theory of liquid mixtures based on a simple molecular model is developed which describes the equilibrium state as the result of a coupling between a "chemical" and a "statistical" equilibrium. The intermolecular interactions are taken into account by considering "complexes" formed between a given molecule and its z nearest neighbours. The equilibrium mole fractions of these complexes are calculated by application of the ideal law of mass action to an appropriate set of "exchange equilibria". Formulae for the excess functions GE and HE and for the activities of the components are derived for the cases z=1 and z=4. GE depends on an equilibrium constant K describing the deviation from random distribution of the equilibrium mole fractions of the complexes. HE depends on K and on an energy parameter w which is related to differences of pair interactions. K and w are independent parameters, and there is no limitation in respect to amount and sign of the excess functions. The conditions for the existence of a critical solution point are formulated; at this point GE has a value of about 0.56 R T. If a model with two equilibrium constants is used allowing for instance competition between "self-association" and "complex-formation", the existence of closed miscibility gaps becomes possible. Closed miscibility curves are calculated and the conditions for their appearance are discussed. The relations between this theory and Guggenheim's statistical lattice theory of symmetrical mixtures are pointed out.
Es wird das Mikrowellenspektrum von Fluorwasserstoffassoziaten im X-und K-Band bei -70 °C und 0,01 Torr gemessen und analysiert. Dazu wird ein erstelltes Frequenzprogramm für den asymmetrischen Kreisel verwendet, sowie ein Extrapolationsprogramm, das eine in der Literatur angegebene druck-und temperaturabhängige Verteilung der Fluorwasserstoffassoziate auf für Mikrowellenspektroskopie geeignete Drücke und Temperaturen umzurechnen erlaubt. Es zeigt sich, daß planare hexamere und heptamere Fluorwasserstoffassoziate vorliegen mit F-F-F-Winkeln von etwa 104° und H-F-Bindungslängen von 0,9997 Å bzw. 0,9640 Å. Die Längen der Wasserstoff brücken sind 1,4998 Å bzw. 1,6105 Å. Ein Vergleich der Bindungslängen zeigt, daß bei Anlagerung von H-F an (HF)6 eine Kontraktion der Fluorwasserstoffbindung um 3,5% und eine Dilatation der Wasserstoffbrückenbindung um 1% stattfindet. Dieses Ergebnis steht im Einklang mit der oben erwähnten Assoziatverteilung, die eine Minderung der Kettenstabilität beim Übergang von hexamerer zu heptamerer Kette erwarten läßt.
We investigate the possibility of selfconsistent solutions for antiferromagnetism in the Hubbard model in the decoupling of the Greens functions introduced by Hubbard in his first paper. On the base of this approximation Arai has calculated the band splitting for antiferromagnetism, but, as will be shown in this paper, Hubbard's approach fails to yield antiferromagnetism for nearest neighbour hopping in the same way as it does not yield ferromagnetism, and no selfconsistent solutions of the problem beyond the well known paramagnetic solution do exist.
El complejo se compone de: — un rascacielos con planta sensiblemente cuadrada y 38 m de altura, y — un bloque rectangular, más bajo, de 9,90 m de alto. El primero alberga las oficinas, y el segundo se destina a cubrir todas las exigencias que se derivan del funcionamiento de un ordenador IBM. Su estructura, a base de núcleos verticales de hormigón armado, forjados nervados y cerramientos compuestos de piezas de hormigón, prefabricadas, con grandes zonas acristaladas. Hay motivos ornamentales, como la escalera helicoidal interior, de hormigón visto, y la plaza enlosada, con estanques y jardineras. Aparcamiento en el sótano.
Este hangar, de grandes dimensiones, se ha construido, por la Deutsche Lufthansa, para alojar seis aviones del tipo Boeing 747 o mayores y tiene unos 30.000 m2 de superficie, 22 m de altura libre y puerta de 21,50 m de altura útil, con posibilidades de ampliaciones futuras. Convocado el correspondiente concurso, se eligió la solución que se expone en el artículo. Consiste, fundamentalmente, en elementos verticales, de diseño original y muy funcional, de hormigón armado visto, y cubierta colgada, de hormigón ligero pretensado, dado que era la que ofrecía mayores ventajas desde un triple punto de vista: económico, técnico y de posible y fácil ampliación.
Constituye el Centro Noroeste un ambicioso proyecto que viene a catalizar todas las actividades más importantes de un gran sector de la ciudad de Francfort. Proyectado en cuatro planos superpuestos, para conseguir un fluido desarrollo del tráfico, crea una serie de calles interiores, sin tráfico rodado, en las que se desarrolla la actividad comercial y de esparcimiento. Debido a los muchos intereses públicos y privados que se conjugaban en el proyecto, y tras largos estudios y discusiones, hubo que llegar a fórmulas de aprovechamiento que complacieran a todos en lo posible: sistema Leasing, para edificios públicos; contratos entre el municipio y adjudicatarios; alquiler ajustable en los edificios oficiales; etc. Como elementos interesantes en el proyecto pueden destacarse: la estación del ferrocarril metropolitano especialmente dotada de revestimiento antiacústico; la planta de estacionamiento para más de 2.000 vehículos, con entradas y salidas especiales, evitando toda clase de cruces; el sistema de planos de peatones, y abastecimiento con calles interiores para entrega de mercancías, rampas especiales, zonas de paso, etc.
En el artículo se describe la construcción de esta instalación singular, destinada a utilizar la combustión de las basuras de la ciudad para fines calefactores y productores de energía eléctrica al servicio de la propia ciudad. Se explica igualmente el proceso seguido para el aprovechamiento integral de residuos cuyo almacenamiento constituía, antiguamente, un verdadero problema en las grandes urbes. El edificio se ha realizado a base de hormigón armado, ladrillo refractario y vigas metálicas en la cubierta.