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  • Artikel  (102)
  • Springer  (102)
  • 2005-2009  (42)
  • 1995-1999  (38)
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  • Artikel  (102)
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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
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  • 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
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    Artikel (Nationallizenzen)
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  • 3
    Digitale Medien
    Digitale Medien
    Carbohydrates of influenza virus. Structure of the oligosaccharides linked to asparagines 406 and 478 in the hemagglutinin of fowl plague virus, strain dutch (1987)
    Springer
    Glycoconjugate journal 4 (1987), S. 17-32 
    Details
    ISSN: 1573-4986
    Schlagwort(e): influenza virus ; hemagglutinin ; glycoprotein glycans ; oligosaccharide structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Fowl plague virus, strain Dutch, was metabolically labeled withd-[2-3H]mannose, or withd-[6-3H]glucosamine, and the small subunit (HA2; 0.8 mg in total) of the viral hemagglutinin was isolated by preparative sodium dodecylsulfate-polyacrylamide gel electrophoresis. After proteolytic digestion, the radioactive oligosaccharides were sequentially liberated from the glycopeptides by treatment with different endo-β-N-acetylglucosaminidases and with peptide:N-glycosidase or, finally, by hydrazinolysis. In this manner, four groups of glycans could be obtained by consecutive gel filtrations and were subfractionated by HPLC. The structures of the individual oligosaccharides were analyzed by micromethylation, by acetolysis or by digestion with exoglycosidases. The major species amongst the high mannose glycans at Ans-406 of the viral glycopolypeptide were found to be Manα1-2Manα1-3(Manα1-2Manα1-6)Manα1-6(Manα1-2Manα1-2Manα1-3)Manβ1-4GlcNacβ1-4GlcNAc and Manα1-3(Manα1-2Manα1-6)Manα1-6(Manα1-2Manα1-2Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc, while the complex glycans at Asn-478 are predominantly GlcNAcβ1-2Manα1-3(GlcNAcβ1-2Manα1-6)Manβ1-4GlcNAcβ1-4GlcNAc (lacking, in part, one of the outerN-acetylglucosamine residues) and GlcNAcβ1-2Manα1-3(Galβ1-4GlcNAcβ1-2Manα1-6)Manβ1-4GlcNAcβ1-4GlcNAc.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01048441
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  • 4
    Digitale Medien
    Digitale Medien
    Host-cell-specific glycosylation of HIV-2 envelope glycoprotein (1997)
    Springer
    Glycoconjugate journal 14 (1997), S. 785-793 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1018577619036
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  • 5
    facet.materialart.
    Unbekannt
    Spectroscopic properties of dissolved humic substances ? a reflection of land use history in a fen area (1999)
    Springer
    Details
    Publikationsdatum: 1999-11-01
    Print ISSN: 0168-2563
    Digitale ISSN: 1573-515X
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Publiziert von Springer
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  • 6
    facet.materialart.
    Unbekannt
    Carbohydrates of influenza virus. Structure of the oligosaccharides linked to asparagines 406 and 478 in the hemagglutinin of fowl plague virus, strain dutch (1987)
    Springer
    Details
    Publikationsdatum: 1987-01-01
    Print ISSN: 0282-0080
    Digitale ISSN: 1573-4986
    Thema: Chemie und Pharmazie
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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    AKTUELLE ARTIKEL
  • 7
    Digitale Medien
    Digitale Medien
    Synchronized delivery and playout of distributed stored multimedia streams (1999)
    Springer
    Multimedia systems 7 (1999), S. 70-90 
    Details
    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
    URL: http://dx.doi.org/10.1007/s005300050112
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  • 8
    Digitale Medien
    Digitale Medien
    Characterization of groundwater humic and fulvic acids of different origin by GPC with UV/Vis and fluorescence detection (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 737-745 
    Details
    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
    URL: http://dx.doi.org/10.1007/s002160051424
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  • 9
    Digitale Medien
    Digitale Medien
    Zeta function determinant of the Laplace operator on theD-dimensional ball (1996)
    Springer
    Communications in mathematical physics 179 (1996), S. 215-234 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF02103720
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  • 10
    Digitale Medien
    Digitale Medien
    A novel quadruple beam imaging polarimeter and its application to Comet Tanaka-Machholz 1992 X (1996)
    Springer
    Astrophysics and space science 239 (1996), S. 259-274 
    Details
    ISSN: 1572-946X
    Schlagwort(e): Polarimeters ; Comet Tanaka-Machholz 1992 X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract For observations of solar system objects an imaging polarimeter has been constructed as an auxiliary instrument for a f/15 focal reducer. With this instrument simultaneous measurement of theQ andU Stokes parameters is possible. It contains no moving parts such as a moving λ/2 retarder. The polarizer consists of two Wollaston prisms which are combined to form a single optical element. Their polarization angles differ by 45°. This compound polarizer is placed in the exit pupil of the afocal telescope-collimator system of the focal reducer and splits the exit pupil into halves. In this way four polarized beams with E-vector orientations 0°, 90°, 45°, and 135° emerge from the exit pupil. These are intercepted by the camera lens of the focal reducer system and imaged simultaneously on the CCD detector. With a properly designed field mask at the Cassegrain focus, the four beams are imaged without overlap. As a demonstration of the capabilities of this quadruple-beam Wollaston-prism polarimeter, we present observations of comet Tanaka-Machholz 1992 X in May 1992. The advantages, shortcomings, and possible improvements of the instrument are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00645780
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