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  • Springer  (59)
  • 1995-1999  (38)
  • 1975-1979  (21)
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  • 1
    Electronic Resource
    Electronic Resource
    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
    Keywords: dissolved humic substances ; FTIR spectroscopy ; land use history ; peat ; synchronous fluorescence spectroscopy ; UV/VIS spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006134214244
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  • 2
    Electronic Resource
    Electronic Resource
    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
    Keywords: dissolved humic substances ; FTIR spectroscopy ; land use history ; peat ; synchronous fluorescence spectroscopy ; UV/VIS spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00994924
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  • 3
    Electronic Resource
    Electronic Resource
    Host-cell-specific glycosylation of HIV-2 envelope glycoprotein (1997)
    Springer
    Glycoconjugate journal 14 (1997), S. 785-793 
    Details
    ISSN: 1573-4986
    Keywords: glycoprotein ; glycosylation ; gp120 ; HIV ; MALDI-TOF-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018577619036
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  • 4
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    Unknown
    Spectroscopic properties of dissolved humic substances ? a reflection of land use history in a fen area (1999)
    Springer
    Details
    Publication Date: 1999-11-01
    Print ISSN: 0168-2563
    Electronic ISSN: 1573-515X
    Topics: Chemistry and Pharmacology , Geosciences
    Published by Springer
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    PAPER CURRENT
  • 5
    Electronic Resource
    Electronic Resource
    Electromagnetic fields of a vertical magnetic dipole above a laterally inhomogeneous thin layer of conductive overburden (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 181-197 
    Details
    ISSN: 1420-9136
    Keywords: Electromagnetic field ; Vertical magnetic dipole ; Thin conductive sheet ; Lateral conductivity variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An analytical formulation is developed for the resultant electromagnetic field of an oscillating vertical magnetic dipole located over a thin conductive sheet of infinite extent. The sheet is characterized by a conductivity-thickness product or conductance σd that may be a function of the horizontal coordinates. The system of integral equations arising in the general formulation is simplified greatly when azimuthal symmetry prevails. Numerical results for a Gaussian variation of σd in the radial direction are presented for the case of a symmetrically located source. These results are for the fields at the level of the source dipole over the conductive sheet. It is shown that the quadrature response of the sheet is enhanced when there is rapid variation of the conductance. The null in the resultant wave tilt is also found to be shifted toward the direction of increasing conductance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878992
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  • 6
    Electronic Resource
    Electronic Resource
    Reelle algebraische Funktionen mit vorgegebenen Null- und Polstellen (1977)
    Springer
    Manuscripta mathematica 22 (1977), S. 87-103 
    Details
    ISSN: 1432-1785
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This note continues the investigations of Knebusch on algebraic curves over real closed fields and was initiated by reading [3]. Especially we ask for the existence of real algebraic functions with given zeroes and poles, a question going back to Witt [4]. We study the real nature of coverings of real algebraic curves, and if the covering has degree two, we get algebraic proofs for results, which in the classical case have been obtained by topological methods in [2].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01182069
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  • 7
    Electronic Resource
    Electronic Resource
    Überlagerungen berandeter Kleinscher Flächen (1977)
    Springer
    Mathematische Annalen 228 (1977), S. 101-111 
    Details
    ISSN: 1432-1807
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01351166
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  • 8
    Electronic Resource
    Electronic Resource
    Synchronized delivery and playout of distributed stored multimedia streams (1999)
    Springer
    Multimedia systems 7 (1999), S. 70-90 
    Details
    ISSN: 1432-1882
    Keywords: Key words:Sychronization – Multimedia streams – Video server
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005300050112
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  • 9
    Electronic Resource
    Electronic Resource
    Expression of vascular endothelial growth factor during the development of cardiac hypertrophy in spontaneously hypertensive rats (1998)
    Springer
    Molecular and cellular biochemistry 187 (1998), S. 141-146 
    Details
    ISSN: 1573-4919
    Keywords: VEGF ; hypertrophy ; spontaneously hypertensive rat ; coronary flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Left ventricular hypertrophy (LVH) is often associated with an impaired maximal coronary blood flow and increases the vulnerability of the heart tissue to ischaemia. In this study, the correlation between coronary blood flow and expression of the vascular endothelial growth factor (VEGF) mRNA was investigated. Using both haemodynamic measurements and analysis of mRNA, we have demonstrated that during development of LVH, in spontaneously hypertensive rats (SHR), an impaired maximal coronary flow at 12 weeks of age is associated with low levels of VEGF mRNA. However, in older SHR (32 weeks) with stabilised hypertrophy and a normal maximal coronary flow response, VEGF mRNA levels are increased three-fold. These results suggest that the mechanism for the impaired flow, observed in some types of cardiac hypertrophy, might involve an inadequate growth of the coronary vessels due to insufficient activation of the VEGF gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006887510678
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  • 10
    Electronic Resource
    Electronic Resource
    Scaling for the fixed-angle scattering amplitude in the framework of the Dyson-Jost-Lehmann representation (1976)
    Springer
    Theoretical and mathematical physics 28 (1976), S. 699-708 
    Details
    ISSN: 1573-9333
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029026
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