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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 4 (1996), S. 0 
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: This paper describes a practical technique, tested experimentally, for rehabilitating degraded semiarid landscapes in Australia. This rehabilitation technique is based on the ecological principle that semiarid landscapes are spatially organized as patchy, source-sink systems; this patchy organization functions to conserve limited water and nutrients within the system. The aim was to rebuild vegetation patchiness, lost through decades of utilization of these landscapes as rangelands. Patches were reconstructed from large tree branches and shrubs obtained locally and placed in elongated piles along contours. These piles of branches were very effective in recreating productive soil patches within the landscape, as described in part I of this study. These new patchy habitats promoted the establishment and growth of perennial grasses. Although the foliage cover of these grasses declined into a drought, which started before the end of the experiment, plant survivorship remained high. This suggests that patches also function as refugia for organisms during droughts. The patches of branches remained robust and functional, even under grazing impacts, although plant growth and survival were significantly higher within an ungrazed paddock than in a grazed paddock.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Restoration ecology 4 (1996), S. 0 
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: A rehabilitation procedure designed to reestablish resource control processes in a degraded Acacia aneura woodland was successful in improving soil nitrogen and carbon content, exchange properties, and water infiltration rates. Soil respiration rates and soil fauna populations increased, and soil temperatures were moderated. The procedure comprised laying piles of branches in patches on the contour of bare, gently sloping landscapes, with the expectation that soil, water, and litter would accumulate in these branch piles, thus improving the soil habitat and its productive potential. The procedure was derived from landscape function analysis, indicating that surface water flow was the principal means of resource transfer in these landscapes. Under degradation such overland flow results in a loss of resources. This rehabilitation procedure reversed loss processes, resulting in gains in the productive potential of soils within patches. This procedure was successful despite grazing pressure being maintained throughout the experiment.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: The Ag-Bi-O system has been experimentally studied using differential thermal analysis (DTA) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), and thermodynamically optimized. The temperatures of the eutectic, monotectic, and Bi2O3 allotropic transformations have been measured in N2, in air, and in O2 by DTA. There are no ternary phases stable at ambient pressure. Presently measured transformation temperatures have been combined with existing oxygen activity measurements in the metal liquid to optimize thermodynamic parameters describing the liquid phase. The resulting fit is excellent. EDX measurements of the composition in the oxide liquid have a rather low precision but confirm the thermodynamic optimization. However, some uncertainties remain concerning the liquid composition at the eutectic transformation and the shape of the miscibility gap at higher temperatures.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: The experimental data on the oxide portion of the Bi–Sr–O system have been reviewed, and an optimized thermodynamic description is presented. There are at least seven stable ternary oxide phases, two of which show considerable solid-solution ranges. At least two phases—δ-Bi2O3 and the rhombohedral β-phase—are good oxygen-ion conductors. Most of the phases are confined to the Bi2O3-SrO line at ambient oxygen partial pressure; however, in the SrO-rich portion, there are at least two phases with oxygen in excess, i.e., with bismuth in the oxidation state Bi5+ instead of the usual Bi3+. There are rather large differences between different experimental data sets; nevertheless, a reasonably consistent set of data can be chosen for the optimization.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: The phase diagram and thermodynamic data on the Sr–Cu–O system at a total pressure of 105 Pa (1 bar) have been reviewed and assessed. Gibbs energy functions for the ternary oxides Sr2CuO3, SrCuO2, Sr14Cu24O41, SrCu2O2, and the liquid phase have been optimized, and a consistent thermodynamic description is presented. Calculated SrOCuOx phase diagrams in air and in 1.01 ×105 Pa (1.01 bar) O2, the oxygen potential diagram, and various thermodynamic properties are shown and compared to experimental data.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Inorganic chemistry 9 (1970), S. 607-611 
    ISSN: 1520-510X
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    British journal of educational technology 4 (1973), S. 0 
    ISSN: 1467-8535
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Pädagogik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 13 (1973), S. 0 
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary. Linuron, 2,4-D-aniine, propachlor, pyriclor and cypromid, singly and mixture with atrazine, were compared with atrazine and fluromidine alone for effectiveness of weed control in maize on Oxford clay soil. Pre-emergence applications were made under wet conditions and atrazine, even at 0·28 kg/ha a.i. gave an excellent control of three main weeds, Stellaria media, Veronica spp. and Polygonum aviculare, and at 0·56 kg/ha also killed Aethusa cynapium. Fluromidine was comparable with atrazine, but linuron,2,4-D-amine, propachlor and pyriclor were less effective. Post-emergence treatments were less satisfactory. High doses of atrazine were needed for good weed control. Acynapium was resistant to pyriclor and cypromid and P. aviculare to fluromidine. 2,4-Daminewas ineffective, but atrazine/2,4-D-amine mixtures were more effective than the individual components for the control of P. aviculare. Pyriclor, at 0·56 kg/ha pre-emergenceand cypromid at 2·24 kg/ha post-emergence directly reduced the yield of the crop.Utilisation de I'atrazine à faible dose, seule et en mélange avec d'autres herbicides, dans les culturesde maïs
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 13 (1973), S. 0 
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary. The effectiveness of pre-emergence applications of 2,4-D for weed control in maize was studied In five experiments, in comparison with other herbicide treatments. 2,4-D-aimne applied before crop emergence gave satisfactory weed control if the subsequent conditions were wet, but post-emerge nee applications only killed some species (Chenopodium album and Atriplex patula.) A combination of 2,4-D-amine, applied pre-emergence to a moist soil and subsequently as a foliar spray, controlled completely C. album, A. patula, Stellaria media and Veronica spp. Pre-emergence applications of simazine gave better weed control with less need for rain soon after application. Only A. patula was usually resistant. Pre-emergence treatments of atrazine killed all weeds whilst linuron controlled S. media, A. patula., C. album and Sonchus oleraceus but not Veronica spp.Irrigation experiments showed that weed competition for water was largely responsible for the depressions in the early growth of maize when the conditions were dry. Final yield largely reflected the degrees of weed control attained by the herbicidal treatments. Only 2,4-D applied pre-emergence, and followed by heavy rain caused a direct depression in yield.Effects des herbicides sur la productivityé du mals fourrage avec référence particuliére aux applications en pré-levée du 2,4-D amine
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: Direct coagulation casting is a novel near-net-shape method for forming ceramic green bodies from homogenous high-solids-loaded particle suspensions. It is based on the principle of the in situcoagulation of a powder suspension via a reaction-rate-controlled internal-enzyme(urease)-catalyzed reaction after casting. Low-viscosity (〈3 Pas) suspensions with a high solids loading (〉62 vol%) of SiC, boron, and carbon powder mixtures with a high surface area (〉7-10 m2/g) have been prepared at pH = 10. Salt ions (up to 1-2 mol/L) are created by the urease-catalyzed decomposition of urea, to destabilize the suspensions. The coagulation kinetics and the strength of the wet green bodies have been investigated. The reaction rate is strongly dependent on the temperature (in the range of 5°-30°C) and the enzyme concentration (for the range of 4-16 units/g SiC) and is independent of the substrate (urea) concentration for urea concentrations of 〈2 wt%, based on the powder content. The resulting green bodies show no shrinkage during coagulation and 1%-2% linear shrinkage during drying. The compressive strengths of the wet green bodies are as high as 60 kPa and increase as the coagulation time increases. The wet green strength of the coagulated suspensions scales with the solids content, according to a power law with an exponent of 11, in the range of 56-61 vol% solids content. The possibilities of fabricating high-solids-containing complex SiC green and sintered components with homogenous microstructures and high sintered densities are demonstrated.
    Materialart: Digitale Medien
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