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  • 1995-1999  (8)
  • 1975-1979  (3)
  • 1960-1964  (4)
  • 1
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The molecular-beam-epitaxial growth of InxGa1−xAs on GaAs or AlyGa1−yAs leads to a variation of In content with depth, due to In segregation. However, by predepositing In at the beginning of InxGa1−xAs growth, and also thermally removing the excess In at the end, we can produce a layer with the ideal "square'' In profile. We find that the performance of AlyGa1−yAs/InxGa1−xAs/GaAs high electron mobility transistors is most enhanced by the predeposition step alone. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Environmental science & technology 11 (1977), S. 182-188 
    ISSN: 1520-5851
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Energietechnik
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Cytosolic Ca2+· ([Ca2+]i, and elongation growth were measured in the roots of Arabidopsis thaliana. Exposure of plant tissues to high NaCl and abscisic acid (ABA) concentrations results in a reduction in the rate of growth, but the mechanism by which growth is inhibited is not understood. Both NaCl and ABA treatments are known to influence [Ca2+]i, and in this study we measured the effects of salinity and ABA on [Ca2+]i in cells from the meristematic region of Arabidopsis roots. The Ca2+-sensitive dye Fura-2 and ratiometric techniques were used to measure [Ca2+]i in cells of the root meristem region. Resting [Ca2+]i was found to be between 100 and 200 μmol m−3 in roots of untreated plants. Resting [Ca2+]i changed in response to changes in the [Ca2+] surrounding growing roots. An increase of external [Ca2+] increased [Ca2+]i; conversely, a decrease of external [Ca2+] decreased [Ca2+]i. Exposure of roots to NaCl caused a rapid reduction of [Ca2+]i, a response that was proportional to the external NaCl concentration. Thus, as the NaCl concentration was increased, [Ca2+]i in root meristematic cells decreased. Root elongation was also inhibited in proportion to the external NaCl concentration, with maximal inhibition occurring at 120 mol m−3 NaCl. The [Ca2+]i of root meristem cells also changed in response to ABA, and the magnitude of the effect of ABA was dependent upon ABA concentration. Treatment with 0.2 mmol m−3 ABA caused a momentary increase in [Ca2+]i followed by a decrease after 15 min, but 10 mmol m−3 ABA caused an immediate decline in [Ca2+]i. There was a strong positive correlation between [Ca2+]i and root elongation rates. Experiments with the ABA-deficient Arabidopsis mutant aba-3 indicated that the reduction in [Ca2+]i brought about by NaCl was unlikely to be mediated via changes in endogenous ABA. Experiments with solutes such as sorbitol, KCl and NaNO3 indicated that the effects of NaCl could be mimicked by other solutes and was not specific for NaCl.
    Materialart: Digitale Medien
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  • 4
    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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  • 5
    Digitale Medien
    Digitale Medien
    [s.l.] : Macmillan Magazines Ltd.
    Nature 400 (1999), S. 551-554 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The reduction in the amount of ozone in the atmospheric column over the Arctic region, observed during the 1990s,, resembles the onset of the Antarctic ozone ‘hole’ in the mid-1980s, but the two polar regions differ significantly with respect to the relative contributions of ...
    Materialart: Digitale Medien
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  • 6
    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
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  • 7
    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
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  • 8
    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
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 44 (1995), S. S5 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 137 (1998), S. 345-350 
    ISSN: 1432-2072
    Schlagwort(e): Key words Nicotine nasal spray ; Smoking cessation ; Nicotine replacement ; Cotinine replacement ; Expired carbon monoxide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Nicotine nasal spray (NNS) is generally considered to be an effective smoking cessation aid, but all studies to date of NNS effectiveness have also utilized group therapy sessions or frequent laboratory visits to support their subjects’ stop smoking efforts. We studied 50 volunteers before they attempted to quit smoking and again at 1, 2 and 3 months after they received NNS to assist them in quitting smoking. No other stop smoking intervention was used, which more closely mimics the common practice of many individuals trying to stop smoking with the aid of a nicotine replacement product but without other supportive interventions. We found that 50% of the subjects quit smoking for the first month, 34% were still abstinent after 2 months and 32% quit smoking for 3 months. Those who quit smoking for the entire 3 months and who continued regular NNS use throughout had 67% cotinine replacement at the end of the first month, while another group which quit smoking for only the first month with the aid of NNS had 42% cotinine replacement at the end of that month. Our data confirm that NNS is an effective smoking cessation aid, but our abstinent rate at 3 months is slightly lower than in other studies in which group therapy was provided. Our data also indicate that higher NNS-induced cotinine replacement during the first month of quitting smoking (suggesting more frequent use of NNS) is associated with longer term quit-smoking success rate.
    Materialart: Digitale Medien
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