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  • Springer  (75)
  • American Geophysical Union  (20)
  • Paleontological Society  (8)
  • American Meteorological Society (AMS)
  • 2000-2004  (32)
  • 1995-1999  (48)
  • 1980-1984  (23)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 47 (1999), S. 219-238 
    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
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Biogeochemistry 47 (1999), S. 219-238 
    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
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Glycoconjugate journal 14 (1997), S. 785-793 
    ISSN: 1573-4986
    Schlagwort(e): glycoprotein ; glycosylation ; gp120 ; HIV ; MALDI-TOF-MS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Neutral complex-type N-glycans of the envelope glycoprotein 120 of HIV-2, propagated in different host cells, display cell-type specific variations. In order to identify typical structural elements, glycans were analysed by gel filtration, by enzymic sequencing and, in part, by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The characteristic substituents of di- tri- and tetraantennary carbohydrate units thus observed include N-acetyllactosamine repeats, bisecting N-acetylglucosamine and fucose linked to the chitobiose core as well as to N-acetyllactosamine antennae. Each glycoprotein preparation displayed a characteristic set of glycoforms. Abbreviations: endo H, endo-β-N-acetylglucosaminidase H; E-PHA, Phaseolus vulgaris agglutinin E4; GlcNAcOH, N-acetyl-glucosaminitol; gp120/HUT78(MOLT4/Mφ/PBL/U937), external envelope glycoprotein 120 of HIV-2, strain D194, propagated in HUT78 (MOLT4, Mφ, PBL, U937) cells; gu, glucose units; HPAEC, high-pH anion-exchange chromatography; MALDI-TOF-MS, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; Mφ, human monocytes/macrophages; PBL, human peripheral blood lymphocytes; PNGase F, peptide-N4-(N-acetyl-β-glucosaminyl)asparagine amidase F
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 1999-11-01
    Print ISSN: 0168-2563
    Digitale ISSN: 1573-515X
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Multimedia systems 7 (1999), S. 70-90 
    ISSN: 1432-1882
    Schlagwort(e): Key words:Sychronization – Multimedia streams – Video server
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract. Multimedia streams such as audio and video impose tight temporal constraints for their presentation. Often, related multimedia streams, such as audio and video, must be presented in a synchronized way. We introduce a novel scheme to ensure the continuous and synchronous delivery of distributed stored multimedia streams across a communications network. We propose a new protocol for synchronized playback and compute the buffer required to achieve both, the continuity within a single substream and the synchronization between related substreams. The scheme is very general and does not require synchronized clocks. Using a resynchronization protocol based on buffer level control, the scheme is able to cope with server drop-outs and clock drift. The synchronization scheme has been implemented and the paper concludes with our experimental results.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 1432-0819
    Schlagwort(e): Key words Lava bubble-wall fragments ; Lō'ihi Seamount ; Kīlauea Volcano
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  Glassy bubble-wall fragments, morphologically similar to littoral limu o Pele, have been found in volcanic sands erupted on Lō'ihi Seamount and along the submarine east rift zone of Kīlauea Volcano. The limu o Pele fragments are undegassed with respect to H2O and S and formed by mild steam explosions. Angular glass sand fragments apparently form at similar, and greater, depths by cooling-contraction granulation. The limu o Pele fragments from Lō'ihi Seamount are dominantly tholeiitic basalt containing 6.25–7.25% MgO. None of the limu o Pele samples from Lō'ihi Seamount contains less than 5.57% MgO, suggesting that higher viscosity magmas do not form lava bubbles. The dissolved CO2 and H2O contents of 7 of the limu o Pele fragments indicate eruption at 1200±300 m depth (120±30 bar). These pressures exceed that generally thought to limit steam explosions. We conclude that hydrovolcanic eruptions are possible, with appropriate pre-mixing conditions, at pressures as great as 120 bar.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Archiv der Mathematik 41 (1983), S. 139-142 
    ISSN: 1420-8938
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 737-745 
    ISSN: 1432-1130
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Gel permeation chromatography (GPC) was applied for recognizing the origin of groundwater humic and fulvic acids. GPC was performed with Fraktogel TSK HW-50 in 0.1 M NaCl, pH 8.5 (0.05 M phosphate buffer), 1 mM EDTA, with 10% by volume methanol added. Humic substances from groundwaters and sediments of four different aquifer systems in Germany were isolated, purified and characterized. Both UV/Vis and fluorescence detection were applied. UV/Vis detection was found to be more powerful in identifying differences between the various humic and fulvic acids. The four aquifer systems investigated (“Gorleben”, “Fuhrberg”, “Franconian Albvorland” and “Munich”) differed from one another with respect to hydrological and geochemical conditions. The results showed that the GPC-elution behavior reflects the geochemical environment and origin (source material and generation process) of aquatic humic and fulvic acids.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Communications in mathematical physics 179 (1996), S. 215-234 
    ISSN: 1432-0916
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Abstract We present a direct approach for the calculation of functional determinants of the Laplace operator on balls. Dirichlet and Robin boundary conditions are considered. Using this approach, formulas for any value of the dimension,D, of the ball, can be obtained quite easily. Explicit results are presented here for dimensionsD=2,3,4,5 and 6.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Astrophysics and space science 97 (1983), S. 225-227 
    ISSN: 1572-946X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract HEAO-B (Einstein) satellite measurements with the Imaging Proportional Counter revealed the W UMa binary system TZ Bootis as an X-ray source. It is estimated that the luminosity ratioL x/Lvof this system is about 10−3.8 indicating that TZ Bootis is in the transition region between A- and W-type W UMa systems.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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