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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    European biophysics journal 20 (1991), S. 65-69 
    ISSN: 1432-1017
    Schlagwort(e): Airway epithelium ; Asthma ; Apical membrane ; Ion channel kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract The single channel inside-out patch clamp technique was used to characterize ion channels in the apical membranes of ragweed-sensitized and control canine tracheal epithelial cells maintained in primary culture. Patches were obtained from single isolated cells or from cells at the edges of confluent sheets. A new type of chloride channel was seen in sensitized cells but not in control cells. The channel showed inward rectification in symmetric chloride solutions with conductance varying from 95 pS to 52 pS over the range of −60 mV to 60 mV membrane potential. Channel gating was voltage dependent with maximal opening at about −30 mV Kinetic analysis showed that distributions of closed and open times could both be well fitted by the sums of three exponential components. Rate constants for transitions between the states of a linear kinetic model were calculated, with only one rate being significantly voltage dependent. The possible significance of this channel is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. S57 
    ISSN: 1432-1041
    Schlagwort(e): Renal haemodynamics ; Captopril ; Nifedipine ; Metoprolol ; protein restriction ; celiprolol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Glomerular hyperfiltration and hypertension may contribute to the progression of chronic renal insufficiency regardless of the underlying disease. Protein restriction and antihypertensive treatment are used to slow the decline in renal function. However, little is known about the interaction of protein loading and antihypertensive treatment on glomerular haemodynamics in humans. This paper compares the renal haemodynamic effects ofβ-adrenoceptor blockers with those of the calcium channel antagonist nifedipine and the ACE inhibitor captopril on resting glomerular filtration and during glomerular hyperfiltration. In two separate studies the effects of nifedipine, captopril, metoprolol, and celiprolol on renal haemodynamics have been investigated. In two groups of healthy volunteers (n =13) inulin and PAH clearances were measured, first under fasting conditions and afterwards during aminoacid infusion. In fasting subjects nifedipine and metoprolol induced glomerular hyperfiltration, while celiprolol and captopril did not significantly affect GFR. Without premedication, and also after nifedipine, metoprolol and celiprolol, the aminoacid infusion significantly increased the GFR. After premedication with captopril, however, aminoacid-induced hyperfiltration was prevented. In fasting subjects captopril, celiprolol and metoprolol elevated PAH clearance. With our without premedication aminoacid infusion increased renal plasma flow compared to baseline on the control day. We conclude that in healthy subjects, acute administration of antihypertensive drugs results in different renal haemodynamic responses. In contrast to captopril and celiprolol, nifedipine and metoprolol induce glomerular hyperfiltration like protein loading. Thus, they may counteract the renal haemodynamic effects of protein restriction. Celiprolol behaves similarly to captopril, since it increases renal perfusion without inducing glomerular hyperfiltration, a pattern which might reflect lower glomerular pressure. Only captopril, however, was able to prevent glomerular hyperfiltration induced by aminoacids. If these observations are confirmed during chronic treatment of patients with impaired renal function, they may suggest that certain antihypertensive drugs reverse, while others seem more likely to support the effect of protein restriction on renal haemodynamics and on the progression of renal disease.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 107 (1937), S. 474-484 
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Zusammenfassung Es wird die Einwirkung homogener Kathodenstrahlen im Geschwindigkeitsbereich von etwa 1 bis 50 kV auf normale Selenphotoelemente untersucht, um die beobachtbaren Erscheinungen zu Rückschlüssen auf die Struktur der Elemente und den quantitativen Ablauf des inneren Vorgangs zu verwerten. Es zeigt sich, daß das Verhalten der Elemente gegen Kathodenstrahlen, insbesondere die Abhängigkeit der Erscheinung von der Strahlgeschwindigkeit, einen neuen Weg weist zur Erweiterung unserer im wesentlichen auf optischen Beobachtungen fußenden Kenntnis dieser eigenartigen Stromquellen. Die neuen Befunde lassen außerdem erkennen, wieweit es in praktischer Hinsicht möglich ist, diese Zellen etwa zu Kathodenstrahlmessungen zu verwenden.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 112 (1939), S. 629-647 
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Zusammenfassung Die Arbeit enthält mehrere systematisch durchgeführte Beobachtungsreihen über das Verhalten des Selenphotoelements bei Erregung durch Licht, die neue Gesichtspunkte für die theoretische Beurteilung der bisher nicht voll erkannten Eigenschaften dieses Elements liefern. Es handelt sich insbesondere um das Verhalten im stationären elektrischen Feld, um die Bedeutung der erregenden Lichtart und Lichtstromdichte und um den Einfluß der Temperatur.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 114 (1939), S. 342-353 
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Zusammenfassung Die Arbeit stellt einen weiteren experimentellen Beitrag zur Enthüllung der elementaren Vorgänge im Selenphotoelement dar. Sie verfolgt im besonderen von verschiedenen Seiten den eigenartigen Temperatureinfluß, der in einer vorhergehenden Untersuchung festgestellt werden konnte, und sucht die Mannigfaltigkeit der hierhergehörigen Erscheinungen einheitlich zusammenzufassen. Es ergeben sich gewisse allgemeine, von den Besonderheiten der einzelnen Elemente unabhängige Eigenschaften, die als charakteristische Merkmale des photoelektrischen bzw. stofflichen Verhaltens des Selenphotoelements erscheinen und daher für das theoretische Verständnis desselben bedeutungsvoll sind.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    International journal of fracture 63 (1993), S. 113-134 
    ISSN: 1573-2673
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract In this paper, the stress intensity factors associated with longitudinal axial cracks in pressurised autofrettaged thick cylinders are calculated using the Boundary Element (BE) method. The effect on the stress intensity factors of the presence of a semi-circular erosion on the bore is investigated. Two loading cases are considered; internal pressure and autofrettage residual stresses. The residual stresses are incorporated by using a crack face loading based on the principle of superposition. The effect of the erosions and cracks on the fatigue lifetimes is calculated using the Paris law.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Hyperfine interactions 89 (1994), S. 83-93 
    ISSN: 1572-9540
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Single ionization of H and double ionization of He are investigated using a multiple scattering approach and a correlated final state wavefunction, which satisfies the correct asymptotic condition for the electron and positron impact ionization of atoms. Analyses presented here show the influence of the Coulomb correlations in the final state on the three- and fivefold differential cross sections. Situations are discussed in which consideration of every pair of electron-electron and/or electron-positron correlation in the final state becomes important for physically satisfactory results.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Fresenius' Zeitschrift für analytische Chemie 104 (1936), S. 70-72 
    ISSN: 1618-2650
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    International journal of earth sciences 82 (1993), S. 67-83 
    ISSN: 1437-3262
    Schlagwort(e): Neotectonics ; central Europe ; northern Europe
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract The ‘neotectonic period’ is the youngest period of tectonic evolution and extends up to the present. The beginning of the neotectonic period during the Cenozoic may be regarded as having begun when characteristic changes in the tectonic evolution of a region of interest have occurred for the last time. Changes in the different tectonic facets, which characterize the evolution of a region, need not be simultaneous, and hence the times of the last change may differ between facets. This leads to the definition of a ‘transitional time interval’ wherein elements of both the ‘palaeotectonic’ and neotectonic period are present. The length of this transitional time interval depends on the regional geological evolution. Where a broad transitional time interval exists, the beginning of the neotectonic period may be defined by the earliest time marker by when most of the characteristic changes of the tectonic evolution of the region had occurred. In defining the neotectonic period in central and northern Europe, data on the evolution of the northern Mid-Atlantic ridge and the northern Mediterranean convergence zone, inversion tectonics in northern and central Europe, rifting, regional subsidence and uplift, and the tectonic stress field as well as the evolution of the calcalkaline and alkaline volcanism in central Europe have been taken into account. The chronological evolution of these ‘characteristics’ for the Cenozoic have been analysed with a view to identifying the advent of the neotectonic period. The transition from the end of the palaeotectonic period to the beginning of the neotectonic period extends from the middle early Miocene to the Miocene-Pliocene boundary. The earliest time by when most of the characteristic changes in the tectonic evolution of northern and central Europe had occurred is the early late Miocene. Thus, the neotectonic period can be considered to have begun at approximately 10 Ma before present.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 36 (1993), S. 2625-2642 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A new boundary element solution algorithm for two-dimensional and axisymmetric contact problems with friction, based on an independent discretization of the contacting surfaces and under static and proportional loading conditions, is presented. The solution procedure uses the element shape functions to distribute the geometry, tractions and displacements on each contact element. The contact constraints are then applied between each contacting node and the opposite contact segment. The overall boundary element matrix equations for the contacting bodies are coupled using the contact conditions at the interface without introducing any additional variables into the solution matrix. The algorithm is applied to several two-dimensional and axisymmetric frictional contact examples and the results obtained are in very good agreement with finite element and analytical solutions.
    Zusätzliches Material: 21 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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