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  • 1990-1994  (7)
  • Polymer and Materials Science  (5)
  • Pisum (stem growth)  (2)
  • 1
    ISSN: 1432-2048
    Schlagwort(e): Auxin and stem growth ; Epidermis and stem growth ; Pisum (stem growth) ; Phytochrome stem growth ; Stem elongation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of red (R) and far-red (FR) light on stem elongation and indole-3-acetic acid (IAA) levels was examined in dwarf and tallPisum sativum L. seedlings. Red light reduced the extension-growth rate of etiolated seedlings by 70–90% after 3 h, and this inhibition was reversible by FR. Inhibition occurred throughout the growing zone. After 3 h of R, the level of extractable IAA in whole stem sections from the growing zone of etiolated plants either increased or showed no change. By contrast, extractable IAA from epidermal peels consistently decreased 3 h after R treatments. Decreases of 40% were observed for epidermal peels from the top 1 cm of tall plants receiving 3 h R. Brief R treatments resulted in smaller decreases in epidermal IAA levels and these decreases were not as great when FR followed R. In lightgrown plants, end-of-day FR stimulated growth during the following dark period in a photoreversible manner. The uppermost 1 cm of expanding third internodes was most responsive to the FR. Extractable IAA from epidermal peels from the upper 1 cm of third internodes increased by 30% or more 5 h after FR. When R followed the FR the increases were smaller. Levels of IAA in whole stem sections did not change and were twofold greater than in dark-grown plants. In both dark- and light-grown tall plants, IAA levels were lower in epidermal peels than in whole stem segments. These results provide evidence that IAA is compartmentalized at the tissue level within the growing stem and that phytochrome regulation of stem elongation rates may be partly based on modulating the level of IAA within the epidermis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-2048
    Schlagwort(e): Auxin and stem growth ; Epidermis and stem growth ; Pisum (stem growth) ; Phytochrome stem growth ; Stem elongation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of red (R) and far-red (FR) light on stem elongation and indole-3-acetic acid (IAA) levels was examined in dwarf and tall Pisum sativum L. seedlings. Red light reduced the extension-growth rate of etiolated seedlings by 70–90% after 3 h, and this inhibition was reversible by FR. Inhibition occurred throughout the growing zone. After 3 h of R, the level of extractable IAA in whole stem sections from the growing zone of etiolated plants either increased or showed no change. By contrast, extractable IAA from epidermal peels consistently decreased 3 h after R treatments. Decreases of 40% were observed for epidermal peels from the top 1 cm of tall plants receiving 3 h R. Brief R treatments resulted in smaller decreases in epidermal IAA levels and these decreases were not as great when FR followed R. In lightgrown plants, end-of-day FR stimulated growth during the following dark period in a photoreversible manner. The uppermost 1 cm of expanding third internodes was most responsive to the FR. Extractable IAA from epidermal peels from the upper 1 cm of third internodes increased by 30% or more 5 h after FR. When R followed the FR the increases were smaller. Levels of IAA in whole stem sections did not change and were twofold greater than in dark-grown plants. In both dark- and light-grown tall plants, IAA levels were lower in epidermal peels than in whole stem segments. These results provide evidence that IAA is compartmentalized at the tissue level within the growing stem and that phytochrome regulation of stem elongation rates may be partly based on modulating the level of IAA within the epidermis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: We show how narrow spectral holes burnt into the inhomogeneous absorption of dye doped polymers can be used as extremely sensitive detectors for measuring structural rearrangement processes. A model is suggested which relates the observed hole burning phenomena to the specific heat of the conformation phase space.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 553-554 
    ISSN: 0323-7648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 51-52 
    ISSN: 0323-7648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    ISSN: 0323-7648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Two different hypotheses of the phenomenological process of etching of polymer films in a non isothermal oxygen plasma of a high frequency discharge are discussed: the successive etching on the surface and the formation of an etch-resistant surface layer with a shifting of the degradation processes in polymer bulk. This second model proposed by Valiev requires a complicated system of diffusion processes of plasma species and degradation products. Our findings are in contrast to those of Valiev, but it seems that the plasma modified surface layer plays a dominant role within the ablation process.
    Notizen: Zwei unterschiedliche Vorstellungen zum Ablauf des Abtrags von Polymerschichten in einem nichtisothermen Sauerstoffplasma einer elektrischen Hochfrequenzentladung werden diskutiert: der successive Abbau an der Oberfläche und die plasmaphysikalische Verfestigung der Polymeroberfläche bei gleichzeitiger Verlagerung des Abbaus in des Polymervolumen. Das letztgenannte Modell von Valiev verlangt komplizierte Diffusionsprozesse von abbaufähigen Plasmaspezies und entsprechenden Abbauprodukten. Die hier durchgeführten Modellversuche sprechen in ihren Ergebnissen gegen das Modell von Valiey, wobei jedoch die plasmamodifizierte Polymeroberflächenschicht tatsächlich eine besondere Rolle beim Abbau der gesamten Polymerschicht spielt.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 289-293 
    ISSN: 0323-7648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The investigation of the temperature dependence of polymer etching rates in an oxygen plasma was extented to some more polymers. The complex nature of the etching process becomes obvious, because the temperature dependences are often nonlinear. Characteristic changes in the slope of the curves correspond only in some cases with the glass temperature of the polymers. Therefore these points can also be connected with the formation and etching of adsorption layers. Activation energies of partial processes were determined. Based on the temperature dependence, only some general conclusions on the plasma etching mechanism could be derived.
    Notizen: Die Untersuchung von Temperaturabhängigkeiten der Plasmaätzrate von Polymeren im Sauerstoffplasma wurde auf weitere Polymere ausgedehnt. Die Temperaturabhängigkeit der Plasmaätzrate ist teilweise sehr unterschiedlich, was auf einen sehr komplexen Mechanismus des Ätzprozesses hindeutet. Charakteristische Knickpunkte in den Kurven konnten nur in einigen Fällen mit der Glastemperatur des Polymers in Verbindung gebracht werden. Möglicherweise werden diese Knickpunkte auch durch Abtrag und Bildung von Adsorptionsschichten hervorgerufen. Aktivierungsenergien von Teilprozessen wurden bestimmt. Aus den Temperaturabhängigkeiten allein ließen sich nur allgemeine Schlußfolgerungen über den Mechanismus des Plasmaätzens der einzelnen Polymere ableiten.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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