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  • 1
    Electronic Resource
    Electronic Resource
    Resource partitioning between shrubs and grasses in the Patagonian steppe (1989)
    Springer
    Oecologia 81 (1989), S. 501-505 
    Details
    ISSN: 1432-1939
    Keywords: Resource partitioning ; Steppe ; Water use ; Shrubs ; Patagonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments were conducted in the Patagonian steppe in southern South America to test the following hypotheses: (a) grasses take up most of the water from the upper layers of the soil and utilize frequent and short-duration pulses of water availability; (b) shrubs, on the contrary, take up most of the water from the lower layers of the soil and utilize infrequent and long-duration pulses of water availability. Grasses and shrubs were removed selectively and the performance of plants and the availability of soil resources were monitored. Results supported the overall hypothesis that grasses and shrubs in the Patagonian steppe use mainly different resources. Removal of shrubs did not alter grass production but removal of grasses resulted in a small increase in shrub production which was mediated by an increase in deep soil water and in shrub leaf water potential. The efficiency of utilization of resources freed by grass removal was approximately 25%. Shrubs used water exclusively from lower soil layers. Grasses took up most of the water from upper layers but they were also capable of absorbing water from deep layers. This pattern of water partitioning along with the lack of response in leaf nitrogen to the removal treatments suggested that shrubs may be at a disadvantage to grasses with respect to nutrient capture and led to questions about the role of nutrient recirculation, leaching, and nitrogen fixation in the steppe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378959
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  • 2
    Electronic Resource
    Electronic Resource
    Grazing effects upon plant community structure in subhumid grasslands of Argentina (1986)
    Springer
    Plant ecology 67 (1986), S. 27-32 
    Details
    ISSN: 1573-5052
    Keywords: Argentina ; Basal area ; Community structure ; Diversity ; Dynamics ; Flooding pampa ; Grassland ; Grazing effect ; Leaf area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in plant community structure are identified as a result of grazing in grasslands of the flooding pampa which evolved under supposedly light grazing conditions. The effect of excluding grazing upon total leaf area index was an increase of 30%. The largest response was observed in the distribution of leaves in the canopy. In the grazed areas, most of the green material was concentrated in the 0–5 cm layer while in the ungrazed treatments the largest portion of the leaf area was in the 10–30 cm layer. Grazing exclusion resulted in a small change in total basal area but a larger change in its distribution, from many small tussocks to less numerous large ones. The effect of grazing upon leaf area and basal area was accounted for by changes in vigor as well as by changes in species composition. The major effect of excluding grazing upon species composition was the disappearance of some native planophile species and most of the exotics. The species composition of grazed areas of both communities was very similar while there were large differences between the ungrazed areas and between the grazed and ungrazed areas of the same community. It is suggested that there is a group of species which responds to the coarse-grained ‘signal’ of grazing and its presence can cause dissimilar communities to converge under grazing conditions. The other group of species responded to the fine-grained ‘signal’ of the environmental conditions associated with topography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040315
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The measurement of pressure-dependent perturbed angular correlations of excited41K nuclei recoiling in argon gas (1987)
    Springer
    Hyperfine interactions 36 (1987), S. 263-273 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The time integrated perturbed angular distribution of the 1294 keV γ-transition, deexciting the recoiling41K excited nuclei, was measured as a function of argon gas pressure between 20 and 1000 torr. The pressure dependence presents a strong minimum around 100 torr. The magnetic hyperfine interaction responsible for the perturbation changes randomly due to inelastic charge exchange collisions, with a pressure-dependent and time-dependent correlation time τc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395635
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Raman resonance excitation profile of the μ-oxobis[pentacyanomanganate (III)] ion (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 577-579 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The resonance Raman spectra of potassium μ-oxobis[pentacyanomanganate(III)] cyanide, K7[Mn2O(CN)10]CN, were measured using exciting lines at 356.4, 406.7, 530.9, 568.2, 603.5, 647.1 and 676.4 nm. By combining these data with those obtained previously (excitations at 457.9, 476.5, 488.0, 496.5, 514.5 and 608.6 nm), the excitation profiles were plotted for three totally symmetric vibrations at 1880 (CNax strech), 527 (MnCax stretch) and 259 cm-1 (MnOMn stretch). It was found that the equation derived by Mingardi et al. can adequately express these excitation profiles and that the previous assignment of the electronic transition at 509 nm needs revision.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250180808
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  • 5
    Electronic Resource
    Electronic Resource
    Vibrational and electronic properties of tris(8-hydroxyquinolinato)vanadium (III) (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 555-560 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the electronic, infrared, Raman and pre-resonace Raman spectra of the solid complex tris(8-hydroxyquinolinato)vanadium(III) was performed. The excitation profiles of the vibrational modes that show preresonance on excitation with laser lines within the electronic bands in the visible region are reported and, on this basis and molecular orbital calculations, several vibrational and electronic absorption bands were assigned.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250200902
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Surface-enhanced Raman scattering of the redox pair CO(sep)3+/Co(sep)2+ on silver and copper electrodes (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 725-728 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface-enhanced Raman spectra of the redox pair Co(sep)3+/Co(sep)2+ (sep: sepulchrate) adsorbed on silver and copper electrodes have been obtained in the skeletal region for these compounds and the results were consistent with the redox potential of the species. The role of the anions and cations of the support electrolytes in the adsorption of the Co(sep)3+ on a silver electrode suggests that the compound is adsorbed on the electrode via ion pair formation with the anion specifically adsorbed. From the behaviour of the Raman intensity of the CH2 symmetrical stretching vibration it was possible to estimate the pKa of the Co(sep)2+.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250201104
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  • 7
    Electronic Resource
    Electronic Resource
    Resonance Raman spectrum of the [Cu(HIO6)2]5- anion (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 23-24 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The resonance Raman effect in solid Na5[Cu(HIO6)2].16H2O at room temperature was investigated and the experimental excitation profiles were obtained. From the analysis of the overtone progression of the ν1(A1g) mode, corresponding to the I—O symmetric stretching vibration, the X11 anharmonicity constant was determined. The dependence of the Raman intensities on the scattered frequency is briefly discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250180106
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