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  • 1990-1994  (7)
  • 1960-1964  (4)
  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 14 (1991), S. 0 
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: This paper presents results from an experimental programme to study size effects in J-R curves. Results are presented from unloading compliance R curve tests on different sized single edge notch bend specimens of nickel aluminium bronze and compared with previously published R curve data on a Ti3A1-2.5V titanium and an HY 100 steel alloy. The crack growth resistance was measured in terms of the standard fracture resistance J, J corrected for crack growth and the J modified parameter proposed by Ernst. It was observed that following a region of size independence small specimen J-R curves could fall either above or below the large specimen curve. It was found that although the limit to J controlled crack growth could be extended the limit is not unique but dependent on material type.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 14 (1991), S. 0 
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Abstract— The results of high rate tensile and compact tension fracture toughness tests conducted on BS 4360 ‘A’ grade ship steel are presented. Tensile results are reported for strain rates within the range 10–2–103/s and fracture toughness values at rates of increase of J integral within the range 103–106 N/mm/s. The tensile properties of upper yield, lower yield and UTS are shown to be linearly dependent on the logarithm of strain rate whilst fracture toughness is shown to decrease with increasing loading rate prior to approaching a minimum value. The decrease in fracture toughness with increasing test rate is shown to be related to a change in the micro-mechanism of fracture.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 14 (1991), S. 0 
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Aspects of combined rate-dependent deformation and crack growth in α-titanium at room temperature are examined. Results are presented for tests carried out on pre-cracked three point loaded single edge notch bend and compact tension specimens subjected to constant crack opening displacement rates and constant load. Curves of the ratio of the reference stress to the yield stress as a function of the ratio of the plastic displacement to specimen width are found to be different for different rates. The stress difference between continuously loaded curves and curves obtained from load relaxation tests (“relaxed” curves) is found to be similar to uniaxial results. Earlier uniaxial tests show that the “relaxed” curve represents a boundary below which no further creep takes place. The pre-cracked specimen constant load curves cross the “relaxed” curve, even though the contribution from crack growth to the overall deformation is found to be small. Sustained load crack growth is observed to take place under contained yielding conditions and the sustained load resistance curves are found to be different for different reference stresses.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 191 (1961), S. 95-96 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] To supplement this observation, in particular to provide a ready measure of the quantity of wax, the contact angle of water droplets on the leaves was measured with a microprojector2. Removal of wax by brushing or weathering always lessened the angle of contact. The contribution of wax to the ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 185 (1960), S. 775-775 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Cyclamen. In subdued daylight, or in artificial top lighting, plants which were made to rotate clockwise showed, after two or three days, a loss of turgidity in some of the leaves, which yellowed and died as the experiment continued. Plants turned anti-clockwise were as healthy and turgid as ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 365 (1993), S. 37-39 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] High levels of C1ONO2 have been observed in both hemi-spheres at the edges of the polar winter vortex3'4 and inside the Arctic spring vortex5. We show here for two cases that ozone depletion does not cease once C1ONO2 is formed: (1) assuming that at high latitudes (65° N) all the ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 344 (1990), S. 294-295 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 353 (1991), S. 210-210 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] ON page 244 of this issue1, Kelly and colleagues describe a marked imbalance in the water to be found in winter in the upper tropospheres of the Northern and Southern Hemispheres. The observation may have considerable implications for modellers attempting to forecast the course of climate change. ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 204 (1964), S. 497-499 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The plant organs are stood on, or 'plugged into', 1*5 per cent washed agar-gel blocks and left for a period of time to allow materials to diffuse from the cut surfaces into the agar blocks. The actual number of organs used, the way in which they are placed on the agar, and the size of the agar ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    ISSN: 1432-2048
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Am Blutungssaft des Wurzelsystems vonHelianthus annuus wurde ein gibberellinartiges Wirkungsvermögen festgestellt. Das Vorhandensein dieser Aktivität wurde mittels eines neubeschriebenen einfachen und empfindlichen Tests an Zwergerbsen-Epikotylen sowie mit dem Gerstenendosperm- und dem Zwergmais-Test entdeckt. Die gibberellinartigen Stoffe haben Säurecharakter und sind in Äthylacetat löslich. IhrR f -Wert wurde papierchromatographisch mit Isopropanol: Ammoniak: Wasser=10∶1∶1 v/v als Laufmittel zu 0,6–0,7 ermittelt. Das Maß der von der Wurzel produzierten gibberellinartigen Aktivität lag bei etwa 0,05 μg GH3-Äquivalenten pro Pflanze und Tag. Andere Hinweise auf eine Gibberellinsynthese in Wurzeln werden besprochen und ferner die Möglichkeit, daß in Sproß und Wurzel eine signifikante Wechselbeziehung hinsichtlich der Produktion und Verwendung anderer Wuchsstoffarten besteht.
    Notizen: Summary Gibberellin-like activity was found to be present in bleeding-sap obtained from root systems ofHelianthus annuus. The presence of activity was detected with a newly described simple and sensitive dwarf pea epicotyl assay, and by the barley endosperm and dwarf maize (Zea mays) tests. The gibberellin-like substance, or substances, are acidic and ethyl acetate soluble, having anR f value of 0.6–0.7 in paper chromatography with isopropyl alcohol: ammonia: water (10∶1∶1 v/v). The quantity of gibberellin-like activity produced by the roots was estimated at approximately 0.05 μg GA3-equivalents/plant/day. Other evidence for gibberellin synthesis in roots is discussed, together with the possibility that shoot and root have significant inter-relationships with regard to the production and utilisation of other types of growth hormone.
    Materialart: Digitale Medien
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