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  • 1995-1999  (2)
  • 1970-1974  (1)
  • 1965-1969  (1)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5782-5785 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method for determining surface charge decay [Q(t)], using a coaxial cylindrical capacitor arrangement and an electrometer interfaced to a PC, has been adapted so as to perform relatively straightforward measurement of resistivity in the surface region of insulators. A charge transport model is presented, based on Mott–Gurney diffusion, which allows interpretation of the data especially for the initial phase of surface charge decay. Resistivity measurements are presented for glass, mica, plexiglas, and polyethylene, covering the range 109–1018 Ω m, as an illustration of the useful range of the instrument for static and antistatic materials, particularly in film or sheet form. Values of surface charge diffusion constants have also been determined for the materials. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary An androgen producing tumour of the testis was removed from a boy with pseudopubertas praecox. Urinary excretion of total 17-oxosteroids, androsterone and aetiocholanolone, 11-oxy-17-oxosteroids (particularly 11β-hydroxy-androsterone), pregnandiol, pregnantriol and oestrogens were abnormally high before operation, and had decreased to normal after operation. After incubation of tumour slices with glucose alone androst-4-en-3,17-dione and 11β-hydroxyandrost-4-en-3,17-dione were found; after incubation with androst-4-en-3,17-dione: 11β-hydroxyandrost-4-en-3,17-dione, testosterone and adrenosterone, but no oestrogens were found; after incubation with desoxycorticosterone: corticosterone and 17α-hydroxycorticosterone. A large amount of androst-4-en-3,17-dione was found in Vena spermatica blood, as well as 17α-hydroxyprogesterone, 11β-hydroxyandrost-4-en-3,17-dione and testosterone. The biochemical and morphological aspects are discussed in relation to the clinical manifestations of the tumour. The tumour had the morphological appearance of a Leydig cell adenoma and also showed a high rate of androgen secretion. The finding of 11β-hydroxylase activity in the tumour shows that it possessed a characteristic usually found only in adrenocortical cells. The tumour was conceivably derived from atypical Leydig cells. This type of Leydig cell adenoma is compared with the bilateral tumour-like enlargement of the testis, which is ocassionally observed in congenital adrenogenital syndrome. The common and contrasting characteristics of the two growths are discussed.
    Notes: Zusammenfassung Bei einem Knaben mit einer Pseudopubertas praecox wurde ein androgenproduzierender Hodentumor entfernt. Präoperativ war die Harnausscheidung der gesamten 17-Ketosteroide, von Androsteron und Ätiocholanolon, der 11-Oxy-17-Ketosteroide, insbesondere von 11β-Hydroxy-androsteron, von Pregnandiol, Pregnantriol sowie der Oestrogene abnorm erhöht und fiel nach der Operation auf Normwerte ab. Nach Inkubation von Glucose allein mit Tumorschnitten wurden 11β-Hydroxy-Δ 4-androstendion undΔ 4-Androstendion gefunden, nach Inkubation vonΔ 4-Androstendion: 11β-Hydroxy-Δ 4-androstendion, Testoseron und Adrenosteron, jedoch keine Oestrogene, nach Inkubation von Desoxycorticosteron: Corticosteron und 17α-Hydroxy-desoxy-corticosteron. Im V. spermatica-Blut wurden große MengenΔ 4-Androstendion, ferner 17α-Hydroxy-progesteron, 11β-Hydroxy-Δ 4-androstendion und Testosteron nachgewiesen. Die biochemischen und morphologischen Gesichtspunkte sowie die klinischen Auswirkungen des Tumors werden diskutiert. Morphologisch hatte der Tumor den Aspekt eines Leydigzell-Adenoms. In Übereinstimmung hiermit wurde eine hohe Sekretion von Androgenen festgestellt. Durch den Nachweis einer 11β-Hydroxylase-Aktivität zeigte der Tumor jedoch gleichzeitig eine Eigenschaft, die sonst nur NNR-Zellen zukommt. Der Tumor wird vermutungsweise von atypischen Leydigzellen abgeleitet. Diese Art von Leydigzell-Adenom wird der beidseitigen tumorartigen Hodenvergrößerung, die gelegentlich beim angeb. adrenogenitalen Syndrom beobachtet wird, gegenübergestellt. Die gemeinsamen und unterschiedlichen Eigenschaften der beiden Wucherungen werden besprochen.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1009
    Keywords: KEY WORDS: Cluster analysis; Cumulative impact; Geographic information systems; Landscape ecology; Remote sensing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 26 (1972), S. 53-77 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We introduce a new method for studying the thermodynamic limit for systems of particles with Coulomb interactions. The method is based on calculating the potential energy of the Coulomb interactions from the electric or magnetic fields in the system rather than from the energy of the individual particle — particle interactions. We are able to include the effects of a constant external field being imposed at the boundary of the system. The difficulties associated with Coulomb potentials being not even weakly tempered are overcome by imposing the boundary condition that at the boundary of the region containing the particles, the electric or magnetic field has normal component equal to that of the applied field. We prove that the thermodynamic free energy density exists and is independent of the sequence of regions used to define the limit. We introduce sequences of regions all of the same shape and show that for these sequences of regions the thermodynamic free energy density is independent of shape. Finally, we prove that the thermodynamic free energy is a convex function of the density of particles and of the applied field.
    Type of Medium: Electronic Resource
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