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  • 1990-1994  (13)
  • 1955-1959  (2)
  • 1940-1944  (1)
  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Space science reviews 70 (1994), S. 373-377 
    ISSN: 1572-9672
    Schlagwort(e): Solar corona ; Coronal holes ; Solar wind ; UV spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Profiles of the visible Fe X (6374 Å) coronal emission line as a function of height above the limb were obtained out to 1.16 solar radii in a coronal hole using the NSO/Sacramento Peak Observatory Coronagraph, Universal Spectrograph and a CCD camera. These are the first coronal line profiles obtained as a function of height in a coronal hole from the ground. Analysis of the line widths suggests a large component of nonthermal broadening which increases with height ranging from 40 to 60 km/s, depending upon the assumed temperature or thermal component of the profile.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Fish physiology and biochemistry 10 (1992), S. 55-66 
    ISSN: 1573-5168
    Schlagwort(e): stress ; rainbow trout ; corticosteroids ; steroid conjugates ; GC/MS ; biliary excretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The accumulation of immunoreactive corticosteroids in the bile of rainbow trout during stress was monitored by radioimmunoassay and GUMS. Although plasma cortisol levels were elevated by confinement for 1 hour, biliary levels of free and conjugated steroids in the bile were unaffected. However, after 24 hours confinement, in addition to elevated plasma cortisol levels, free and conjugated steroids in the bile were also significantly higher than in control, unstressed fish. The time-course of change in plasma and biliary corticosteroid levels was determined in rainbow trout subject to 96 hours confinement stress. Free steroid levels in the bile of stressed fish were elevated within 2 hours of the onset of stress, while levels of conjugated steroids were significantly elevated within 4 hours of the onset of confinement. Analysis of bile from stressed fish, by GC/MS, established the major conjugated steroids present to be tetrahydrocortisone (230 μg ml−1 bile), tetrahydrocortisol (75 μg ml−1), cortisone (33.5 μg ml−1), cortisol (25 μg ml−1) and β-cortolone (5 μg ml−1). The data are discussed with reference to the role of cortisone and conjugating enzymes in the clearance of cortisol, and further data are presented to suggest that the analysis of biliary steroid content may provide a suitable means of identifying stressed fish under conditions in which an additional sampling stress is unavoidable.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Solar physics 135 (1991), S. 179-191 
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We describe an ‘electrograph’ instrument designed for measurement of macroscopic electric fields in solar plasmas, using the polarization dependence of line width in Stark-broadened hydrogen Paschen emission lines. Observations of quiescent prominences and limb chromosphere with our electrograph at the NSO/Sac Peak Evans Coronal Facility provide upper limits of 5–10 V cm−1 for transverse macroscopic electric fields in these structures, averaged over an area of about 5 × 7 arc sec. Random thermal motions of hydrogen ions across magnetic field lines generate a quasi-static electric field, which should be distinguishable from pressure broadening in the intensely magnetized chromosphere over a sunspot, given an electrograph sensitivity a factor 2–3 better than that achieved here. Future electrograph measurements of limb flares, post-flare loops and eruptive prominences, even at 5 V cm−1 sensitivity, could provide a useful new test of reconnection and discharge effects in such dynamic structures.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 595-606 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cluster ions from fast atom bombardment of liquid alcohols and nitriles were examined using a continuous-flow technique. Protonated molecular MnH+ species are the dominant cluster ions observed in molecules of formula M. The abundances of the MnH+ cluster ions decrease monotonically with increasing n, and within a homologous series the MnH+ abundance diminishes more rapidly for higher molecular mass compounds. Reaction products (ROH)n(H2O)H+ and (ROH)n(ROR)H+ are observed also in the case of alcohols, and the ion abundances decrease with increasing n. Radiation damage yields fragment ions and ionic alkyl reaction products which are captured in solvent clusters. Semi-empirical molecular orbital methods were used to examine the energetics of cluster ion formation and decomposition pathways. Metastable decomposition processes exhibit only evaporative loss of monomers, with the probability of loss increasing sharply with n. The evaporative ensemble model of Klots was used to predict the cluster size-dependent trends of metastable dissociation processes observed for alcohol and nitrile cluster ions.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 892-898 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Positive and negative cluster ions in methanol have been examined using a direct fast atom bombardment (FAB) probe technique. Positive ion (CH3OH)IIH + clusters with n = 1-28 have been observed and their clusters are the dominant ions in the low-mass region. Cluster-ion reaction products (CH3OH)II(H2O)H+ and (CH3OH)II(CH3OCH3)H+ are observed for a wide range of n and the abundances of these ions decrease with increasing n. The negative ion (CH3OH)II(CH3O)- clusters are also readily observed with n = 0-24 and these form the most-abundant negative ion series at low n. The (CH3OH)II(CH2O)-, (CH3OH)II(HIIO)(CH2O)- and (CH3OH)II(H2OXCH3O)- cluster ions are formed and the abundances of these ions approach those of the (CH3OH)II(CH3O)- ion series at high n. Cluster-ion structures and energetics have been examined using semi-empirical molecular orbital methods.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 25 (1990), S. 174-180 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The influence of the collision gas on doubly charged ion mass spectra of a selected number of hydrocarbons has been examined. Relative abundances of various product ions in 2E spectra, resulting from charge exchange collisions of doubly charged hydrocarbon ions, do not vary drastically as the collision gas is varied. However, the absolute intensities of these doubly charged ion mass spectra increase significantly when the collision gas is changed from argon to methane to isobutane. Tbese observations are rationalized in terms of a multichannel diabatic curve crossing model.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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