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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 24 (1968), S. 972-973 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Es wird eine neue kolorimetrische Schnellmethode zur Bestimmung des Nucleoproteidgehaltes von Tabakmosaikvirus im Saft von Tabakblättern beschrieben. Der Saft wird durch die Chloroform-Wasser-Emulsionstechnik geklärt, das Virus-Nucleoproteid durch 2,0M Trichloressigsäure gefällt und dann in 1,0N NaOH gelöst. Die durch Zusatz von Folin-Phenolreagens entstandene Farbe wird kolorimetrisch bestimmt. Die mit der neuen Methode erhaltenen Resultate stimmen gut mit denjenigen von Aktivvirusbestimmungen überein.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 182 (1965), S. 238-242 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The stability of a uniformly rotating cylindrical plasma configuration in dynamical equilibrium is discussed. Assuming an axial current and sheet currents for the plasma, we have obtained a dispersion relation for non-axisymmetric perturbations. The dispersion relation comes out to be a complex and implicit function of the frequency of perturbations. Here we have discussed the dispersion equation for the modem=1, with the help of numerical computations. It has been shown that rotation has a stabilizing influence, whereas the axial current destabilizes the cylinder.
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  • 3
    Publication Date: 1968-09-01
    Print ISSN: 0014-4754
    Topics: Biology , Medicine
    Published by Springer
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  • 4
    Publication Date: 1965-06-01
    Print ISSN: 0939-7922
    Electronic ISSN: 1431-5831
    Topics: Physics
    Published by Springer
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  • 5
    Publication Date: 1965-05-01
    Description: The stability of a uniformly rotating and infinitely conducting jet with twisted magnetic field is discussed. The dispersion relation is obtained for the non-axisymmetric perturbations; this involves a complex and implicit function of the growth rate. The complex growth rate implies that instability develops as an overstability. The effect of axial current is destabilizing for both the instabilities m = 0 and m = 1 discussed here. The effect of rotation on the stability of the jet is as follows: (a) for the m = 0 mode, rotation always has a destabilizing effect; (b) for the m = 1 mode, rotation has a stabilizing effect for very long-wave perturbations, but for short-wave perturbations it destabilizes the jet. In particular there exists a disturbance of a particular wavelength which is unaffected by the rotation of the jet. © 1965, Cambridge University Press. All rights reserved.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 2 (1969), S. 419-425 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 40 (1968), S. 843-847 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 62 (1968), S. 72-84 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Zellen von Cytophaga hutchinsonii und vegetativer Sporocytophaga myxococcoides produzieren während der Submerskultur in belüftetem Glucose-Medium große Mengen hochviscoser, extracellulärer Schleimstoffe. Im elektronenmikroskopischen Bild erscheint die “Schleimhülle” der Bakterien nach Negativkontrastierung mit Natriumphosphorwolframat als dichtes, weit verzweigtes Netzwerk fibrillärer Elemente, die an der Zelloberfläche entspringen und sich ohne erkennbare äußere Abgrenzung im Substrat ausbreiten. Feinste “Elementarfibrillen” der Schleimsubstanz haben eine Dicke von etwa 30 Å. Demgegenüber wird völlige Abwesenheit einer Schleimhülle bei den Mikrocysten festgestellt, die aus den vegetativen Zellen von Sp. myxococcoides nach Beendigung des logarithmischen Wachstums gebildet werden. Gleichzeitig mit der Mikrocystenbildung wird starke Abnahme der Viscosität im Kulturmedium festgestellt. Mikrocystenbildung scheint mit dem enzymatischen Abbau der Schleimsubstanz einherzugehen. Die Schleime von C. hutchinsonii und Sp. myxococcoides sind wahrscheinlich anionische Heteropolysaccharide. Cytophaga-Schleim enthält die vier Neutralzucker Glucose, Mannose, Arabinose und Xylose; bei Sporocytophaga ist zusätzlich Galaktose vorhanden. Einziger anionischer Baustein ist in beiden Fällen Glucuronsäure, die möglicherweise über Xylose mit den Polymeren verknüpft ist.
    Notes: Summary Cells of Cytophaga hutchinsonii and vegetative Sporocytophaga myxococcoides produce copious amounts of extracellular slime during active growth in liquid, aerated glucose-medium, imparting a high degree of viscosity to the culture. Electron microscopy following negative staining with sodium phosphotungstate reveals the slime substance as densely interwoven network of filamentous material originating on the cell surface and extending far into the medium without any discernable boundary. “Elementary fibrils” of the slime substance have a thickness of about 30 Å. The surrounding layer of filamentous slime is completely absent from the surface of microcysts formed from vegetative cells of Sp. myxococcoides after cessation of logarithmic growth, and the original high viscosity of the cell suspension is greatly reduced. It is concluded that microcyst formation is accompanied by enzymatic breakdown of the extracellular slime substance. Isolated slime materials from both organisms are tentatively identified as anionic heteropolysaccharides. Neutral sugar components of the substance from C. hutchinsonii are glucose, mannose, arabinose and xylose. Sp. myxococcoides slime contains the same sugars and also galactose. Glucuronic acid is the only anionic component in the heteropolysaccharides of both organisms. Preliminary evidence suggests that the uronic acid is linked to the polymers via xylose.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 59 (1967), S. 355-380 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Vegetative Zellen der primitiven Myxobakterien Cytophaga hutchinsonii und Sporocytophaga myxococcoides können in Massenkulturen in belüfteter Glucose-Mineralsalz-Nährlösung gewonnen werden. In Kulturen von Sp. myxococcoides erfolgt bei Verschiebung der Bebrütungstemperatur von 30°C nach 37°C in guter Ausbeute Umwandlung von vegetativen Bakterien in Mikrocysten. Aus vegetativen Zellen und Mikrocysten werden durch kombinierte Behandlung mit Proteinasen, Nucleasen und Extraktion mit anionischen Netzmitteln Zellwände isoliert. Diese bestehen zum größten Teil aus Murein und enthalten die Bausteine Muraminsäure, Glucosamin, 2,6-Diaminopimelinsäure, Glutaminsäure und Alanin im Molverhältnis 1:1:1:1:2. Andere charakteristische Zellwandpolymere wie Proteine, Teichonsäuren oder Polysaccharide wurden in Myxobakterienwänden nicht gefunden. Die Ergebnisse der Chromatographie von Lysozymspaltprodukten und chemische Endgruppenbestimmung durch Dinitrophenylierung sprechen dafür, daß die Mureine der Mxyobakterien, ähnlich wie Mureine Gram-negativer Eubakterien, aus Muropeptiduntereinheiten aufgebaut und durch Peptidbrücken zwischen Muropeptiden vernetzt sind. Im elektronenmikroskopischen Bild erscheinen die Mureinwände der Myxobakterien als schlauchförmige (vegetative Zellen) oder ballonförmige (Mikrocysten) Beutel in der Form der Zellen, aus denen sie erhalten wurden. Sie entsprechen also den von Weidel definierten, formgebenden “Murein Sacculi”. Nach Messungen an elektronenmikroskopischen Bildern von Dünnschnitten beträgt die Wandstärke der Sacculi bei vegetativen Zellen von Sp. myxococcoides etwa 20 Å, bei Mikrocysten etwa 90 Å. Es wird angenommen, daß Zellwände vegetativer Myxobakterien nackte und deshalb biegsame Sacculi sind, die nur aus einer monomolekularen Mureinschicht bestehen. Die um ein Vielfaches dickere Mikrocystenwand wird als Stapel mehrerer aufeinandergelagerter Mureinschichten interpretiert.
    Notes: Summary Vegetative cells of the non-fruiting myxobacteria Cytophaga hutchinsonii and Sporocytophaga myxococcoides were obtained in good yield and defined state of growth from shake cultures in liquid glucose-mineral salts medium. In Sp. myxococcoides a shift of incubation temperature from 30 to 37°C resulted in large scale conversion of vegetative bacteria into microcysts (myxospores). Empty cell walls were isolated from both vegetative myxobacteria and microcysts by combined treatment with proteinases and nucleases and extraction with anionic detergent. Murein (synonyma: mucopolymer, mucopeptide) was found to be the major cell wall polymer in all cases. Amino acid and amino sugar constituents of myxobacterial murein are muramic acid, glucosamine, 2,6-diaminopimelic acid, glutamic acid and alanine occuring in a molar ratio of 1:1:1:1:2. Other typical macromolecular materials, which are prominent accessory cell wall materials in eubacteria, e.g. teichoic acids, proteins and polysaccharides, were not found in the Cytophaga and Sporocytophaga walls. Chromatography of murein fragments obtained by the action of muramidase (lysozyme) and chemical end group determinations indicated that myxobacterial mureins resemble eubacterial mureins in being composed of repeating muropeptidesubunits, which are linked between their peptide side-chains. Electron microscopy revealed the murein cell walls of the two myxobacteria as cell-shaped containers of the size and form of the organisms from which they were derived. The structures thus correspond to the shape-conferring “murein sacculus” of the eubacterial cell wall, as defined by Weidel (Weidel and Pelzer, 1964). The thickness of murein layers in Sporocytophaga cell walls was measured in electron micrographs of cell wall thin-sections and was found to be 20 Å in vegetative cells and 90 Å in microcysts. It is assumed that vegetative cells of myxobacteria may be highly flexible because their cell walls are constructed only of naked tubes of murein monolayer. In the much thicker and inflexible cell walls of microcysts increased rigidity may be brought about by the superposition of several murein monolayers.
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  • 10
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 19 (1965), S. 56-64 
    ISSN: 0001-5520
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences
    Type of Medium: Electronic Resource
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