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  • 06B05  (2)
  • FTIR spectroscopy  (2)
  • Springer  (4)
  • American Institute of Physics (AIP)
  • American Meteorological Society (AMS)
  • Emerald
  • Paleontological Society
  • Wiley
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  • 1990-1994  (2)
  • 1955-1959
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  • Springer  (4)
  • American Institute of Physics (AIP)
  • American Meteorological Society (AMS)
  • Emerald
  • Paleontological Society
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  • 1995-1999  (2)
  • 1990-1994  (2)
  • 1955-1959
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  • 1
    Digitale Medien
    Digitale Medien
    Spectroscopic properties of dissolved humic substances - a reflection of land use history in a fen area (1999)
    Springer
    Biogeochemistry 47 (1999), S. 219-238 
    Details
    ISSN: 1573-515X
    Schlagwort(e): dissolved humic substances ; FTIR spectroscopy ; land use history ; peat ; synchronous fluorescence spectroscopy ; UV/VIS spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract The elemental composition and spectroscopic properties of dissolved fulvic acids isolated from different sampling media (topsoil, ground and surface water) of a natural fen area (high portion of organic soils) were examined to reveal the effects of land use history. These effects need to be known if dissolved humic substances are to be a major factor in identifying the impact of present and future changes in land use. Dissolved fulvic acids (topsoil, groundwater) from highly degraded peatlands (due to a long-term agricultural use) exhibit lower C/N ratios, higher absorption in the UV spectra, and higher absorption at 1,620 cm−1 in the FTIR spectra compared with fulvic acids from relatively intact peatlands. These properties illustrate that long-term agricultural use with high inputs results in increased aromatic structures and a further humification of dissolved fulvic acids due to very strong peat decomposition compared with relatively intact peatlands. Synchronous fluorescence spectra also indicate the higher level of aromatic structures within fulvic acids isolated from sites with long-term agricultural use (high peat decomposition) compared with a land use history resulting in a lower peat decomposition. The different sources of fulvic acids in surface water (precipitation, runoff, interflow, groundwater) are the main reason for these effects not being detected in fulvic acids isolated from surface water. Short-term changes in land use characterized by a transition from crop farming to an unimproved grassland were found not to affect the spectroscopic properties of dissolved fulvic acids. A humification index deduced from the synchronous fluorescence spectra is proposed. We have strong evidence that dissolved humic substances indicate changes in the environmental conditions (both anthropogenic and natural) of wetlands with a high proportion of organic soils.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006134214244
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Spectroscopic properties of dissolved humic substances — a reflection of land use history in a fen area (1999)
    Springer
    Biogeochemistry 47 (1999), S. 219-238 
    Details
    ISSN: 1573-515X
    Schlagwort(e): dissolved humic substances ; FTIR spectroscopy ; land use history ; peat ; synchronous fluorescence spectroscopy ; UV/VIS spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract The elemental composition and spectroscopic properties of dissolved fulvic acids isolated from different sampling media (topsoil, ground and surface water) of a natural fen area (high portion of organic soils) were examined to reveal the effects of land use history. These effects need to be known if dissolved humic substances are to be a major factor in identifying the impact of present and future changes in land use. Dissolved fulvic acids (topsoil, groundwater) from highly degraded peatlands (due to a long-term agricultural use) exhibit lower C/N ratios, higher absorption in the UV spectra, and higher absorption at 1,620 cm−1 in the FTIR spectra compared with fulvic acids from relatively intact peatlands. These properties illustrate that long-term agricultural use with high inputs results in increased aromatic structures and a further humification of dissolved fulvic acids due to very strong peat decomposition compared with relatively intact peatlands. Synchronous fluorescence spectra also indicate the higher level of aromatic structures within fulvic acids isolated from sites with long-term agricultural use (high peat decomposition) compared with a land use history resulting in a lower peat decomposition. The different sources of fulvic acids in surface water (precipitation, runoff, interflow, groundwater) are the main reason for these effects not being detected in fulvic acids isolated from surface water. Short-term changes in land use characterized by a transition from crop farming to an unimproved grassland were found not to affect the spectroscopic properties of dissolved fulvic acids. A humification index deduced from the synchronous fluorescence spectra is proposed. We have strong evidence that dissolved humic substances indicate changes in the environmental conditions (both anthropogenic and natural) of wetlands with a high proportion of organic soils.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00994924
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Generalizing semidistributivity (1993)
    Springer
    Order 10 (1993), S. 77-92 
    Details
    ISSN: 1572-9273
    Schlagwort(e): 06B05 ; 06B20 ; Doubling construction ; semidistributive lattices ; k-semidistributivity ; context ; doubling classes ; pseudovariety
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A latticeL is called congruence normal if it can be generated by doubling of convex sets starting with the one-element lattice. In the special case of intervals, the lattice is called bounded. It has been proven thatL is bounded if and only ifL is congruence normal and semidistributive. In this paper we study the connection between certain classes of convex sets and generalized semidistributive laws. These so-called doubling classes are pseudovarieties which can be described by implications as well as by forbiden substructures. In the end, we examine the structure of the lattice of all doubling classes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01108710
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    On context patterns associated with concept lattices (1993)
    Springer
    Order 10 (1993), S. 363-373 
    Details
    ISSN: 1572-9273
    Schlagwort(e): 06B05 ; 06A15 ; Context ; arrow relation ; concept lattice ; context pattern ; strictly realizable context pattern
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract In this paper, we consider the following reconstruction problem: Given two ordered sets (G, ≤) and (M, ≤) representing join- and meet-irreducible elements, respectively together with three relationsJ, , $${\hbox{\ \hbox{$\mid$}\kern -1em\lower .5em \hbox{$\leftarrow$}}} $$ onG×M modelling comparability (g≤m) and maximal noncomparability with respect tog (g≰m, butg≤m*) and with respect tom (g≰m, butg≤m*). We determine necessary and sufficient conditions for the existence of a finite latticeL and injections α:G→J(L) and β:M→M(L) such that the given order relations and the abstract relations coincide with the one induced by the latticeL.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01108830
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
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