ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    In:  Earthquake Notes, Washington D.C., Bundesanstalt für Geowissenschaften und Rohstoffe, vol. 38, no. 1, pp. 23-28, pp. L09611
    Publication Date: 1967
    Keywords: Seismology ; Magnitude ; Lg-waves
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1741-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Cet article présente l'historique et les résultats de lévaluation de la résistivité électrique du sang et d'autres liquides biologiques, du muscle cardiaque, des muscles du squelette, des poumons, des reins, du foie, de la vesicule biliaire, du pancréas, des tissus nerveux, des vaisseaux, des os et de divers autres tissus. On indique les conditions de mesure lorsque cela est possible.
    Abstract: Zusammenfassung In diser Arbeit wird die historische Entwicklung der Bestimmung des elektrischen Widerstands beschrieben. Tabellierte Daten für den elektrischen Widerstand von Blut, anderen Körperflüssigkeiten, Herzmuskel, Skelettmuskel, Lunge, Niere, Leber, Milz, Pankreas, Nervengewebe, Fett, Knochen und verschiedenen anderen Geweben werden zusammengestellt. Wenn möglich, werden die Meßbedingungen angegeben.
    Notes: Abstract The paper traces the history of, and tabulates determinations of the electrical resistivity of blood, other body fluids, cardiac muscle, skeletal muscle, lung, kidney, liver, spleen, pancreas, nervous tissue, fat, bone, and other miscellaneous tissues. Where possible, the conditions of measurement are given.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1741-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Lorsqu’il est nécessaire de connaître la nature fondamentale d’un phénomène d’origine bioélectrique, on fait appel généralement à une microélectrode connectée à un amplificateur à haute impédance d’entrée. Les micropipettes en verre sont employées aussi bien que les microélectrodes métalliques. Bien que des précautions spéciales soient respectées pour l’usage des micropipettes, on fait d’ordinaire moins attention à l’impédance d’entrée des amplificateurs lors de l’emploi des microélectrodes métalliques, partant du principe que l’impédance de celles-ci est beaucoup plus faible que celle des micropipettes de taille comparable. Ce principle conduit à conclure que la plupart des amplificateurs d’enregistrement des phénomènes bioélectriques peuvent être utilisés en liaison avec des microélectrodes métalliques. Le but de cet article est de montrer l’influence de la surface des microélectrodes métalliques sur la distorsion du signal, enregistré à l’aide d’un amplificateur à impédance résistive commutable. On verra également qu’il existe une relation entre l’aire de la microélectrode et l’impédance d’entrée pour differents taux de distorsion. Dans un article antérieur (Geddes et Baker, 1966) on présentait une telle relation à l’occasion d’enregistrement d’électrocardiogrammes avec de petites électrodes. L’étude présente tendant à préciser cette relation a été faite à partir de l’électomyogramme du gastroenémius de grenouille.
    Abstract: Zusammenfassung Sollen die grundsätzlichen Eigenschaften eines bioelektrischen Vorgangs untersucht werden, benutzt man gewöhnlich eine Mikroelektrode, die mit einem Verstärker von sehr hoher Eingangsimpedanz verbunden ist. Glasmikropipetten und Metallmikroelektroden werden zu diesem Zweck routinemäßig eingesetzt. Obwohl beim Gebrauch von Mikropipetten besondere Vorsichtsmaßnahmen getroffen werden, wird beim Gebrauch von Metallmikroelektroden der Verstärkeriengangsimpedanz weniger Beachtung geschenkt. Es wird nämlich angenommen, daß die Impedanz der Metallelektroden beträchtlich unter der von Mikropipetten ähnlicher Größe liegt. Diese Annahme führt oft zu dem Schluß, daß die meisten Verstärker für die Registrierung bioelektrischer Vorgänge mit Metallmikroelektroden betrieben werden können. Es ist Zweck dieser Arbeit, den Verzerrungstyp einer bioelektrischen Registrierung zu demonstrieren, welcher beim Gebrauch von Metallmikroeletroden verschiedener Flächen auftritt, wenn der Verstärkereingang eine auswählbare resistive Eingangsimpedanz hat. Es wird auch gezeigt, daß eine Beziehung zwischen Elektrodenfläche und Eingangsimpedanz für bestimmte Verzerrungsgrade besteht. In einer vorangegangenen Arbeit (Geddes und Baker, 1966) wurde gezeigt, daß eine solche Beziehung bei der Aufnahme des Elektrokardiogramms mit kleinen Elektroden besteht. In der hier mitgeteilten Untersuching wurde das Elektromyogramm vom Froschgastrocnemius als bioelektrischer Vorgang für die Untersuchung der Beziehung zwischen Eingangsimpedanz und Elektrodenfläche herangezogen.
    Notes: Abstract The high impedance of glass micropipettes is widely recognized and appropriate attention is given to the amplifier input impedance required to reproduce bioelectric events recorded with these electrodes. However, similar precautions are often ignored when using metal microelectrodes, because it is often assumed that their impedance is much lower than micropipettes of comparable size. This paper reports on studies of the relationship between metal microelectrode area and amplifier input impedance required to record faithfully the action potential of frog skeletal muscle. The distortion of the EMG, as the amplifier input impedance was intentionally lowered in discrete steps, is quantitated in terms of the resultant per cent tilt of a square wave inserted along with the action potential. In addition, the impedance vs. frequency relationship is plotted for two metal microelectrodes of 100 and 1600 μ2 in area. This relationship shows the increased impedance at lower frequencies resulting from the capacitance produced by the electrical double layer. Results show that the minimum input impedance required for proper EMG recording ranges from 88 MΩ for steel electrodes of 500 μ2 in area to 1 megohm for electrodes of 125,000 μ2.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1741-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 38 (1967), S. 243-274 
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analyses of populations ofRaphanus growing in the central part of California, from the Sierra Nevada foothills to the Pacific coast, show that pureR. raphanistrum can be found only in the Central Valley, while over the remainder of the area populations of the so-called “wild” (weedy)R. sativus occur. More detailed morphological studies of a number of populations in this area have revealed that the populations of “wild”R. sativus originated by hybridization of the cultivated forms of this species (the radish) with another introduced species, already a weed,R. raphanistrum. The composition of each hybrid population with respect to the proportion of characters of the one or the other species depends upon the habitat it occupies and its geographic location. Populations in inland areas display a high proportion ofR. raphanistrum characters, while in those near the coastR. sativus characters predominate. Artificial hybrids betweenR. raphanistrum and a cultivated form ofR. sativus exhibited about 50% pollen fertility and were heterozygous for a reciprocal translocation. Examination of “wild” populations ofR. sativus revealed that plants heterozygous for a reciprocal translocation are present in varying proportions. Experimental evidence is produced to show that this translocation is identical with that separatingraphanistrum from cultivated forms ofsativus. Thus a cytological proof of the introgression is added to the morphological evidence. Introgression ofraphanistrum characters appears to have been a major factor in converting the erstwhile crop plant,R. sativus, into a highly successful weed in California.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The UV enhancement of recombination among λ bacteriophages was studied in host bacteria that are defective in DNA repair and compared to that observed in wild type host strains. The following conclusions were drawn: 1. The UV enhancement of recombination is even greater in HCR− than in HCR+ host strains. The UV lesions that promote recombination are repaired by host cell reactivation with the same efficiency as are potentially lethal UV lesions. 2. The UV enhancement of λ recombination is the same in HCR+ host strains that are deficient in their own recombination as it is in the wild type hosts. 3. Very few lesions per phage particle are sufficient to stimulate the enhanced recombination. The UV-stimulated recombination occurs during the same time interval as host cell reactivation. 4. There is substantial multiplicity reactivation of UV lesions in λ. Similar numbers of recombination events neutralize similar numbers of UV lesions in HCR+ and HCR− hosts, but a much greater survival increase is observed in the latter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 6 (1967), S. 1948-1951 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 89 (1967), S. 6377-6378 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...