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  • 1995-1999  (5)
  • 1985-1989
  • 1980-1984
  • 1965-1969
  • 1950-1954  (1)
  • 1995  (5)
  • 1950  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Deposition of epitaxially oriented films of cubic silicon carbide on silicon by laser ablation: Microstructure of the silicon–silicon- carbide interface (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 6601-6608 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Excimer laser ablation has been used to deposit epitaxial films of β-SiC on single-crystal Si wafers, in a vacuum, at substrate temperatures between 1050 and 1250 °C. Such films can be grown by ablating ceramic SiC, carbon, or alternating silicon and carbon targets at a range of growth rates. X-ray θ-2θ diffraction shows the presence of strong, sharp reflections from crystal planes parallel to the substrate, 200 and 400 for [100] substrates and 111 and 222 for [111] oriented substrates. Wrong reflections, such as 111 for [100] substrates, are extremely weak or absent, indicating alignment with the substrates. The characterization of these films by a number of techniques is discussed. In all cases the film-substrate interface shows a characteristic microstructure of cavities in the Si substrate, similar to that observed for the carbonization layer initially formed as a precursor for chemical-vapor deposition of SiC films on Si. This implies that the initial film growth, for all cases, involves chemical reaction of the Si substrate with the carbon in the plume as well as transport through the growing film. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.359070
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  • 2
    facet.materialart.
    Unbekannt
    Sammelwerke und Lehrbücher: Alexander Mahr: Volkswirtschaftslehre (Book Review) (1950)
    Wien : Periodicals Archive Online (PAO)
    Journal of economics/Zeitschrift für Nazionalökonomie. 13:1 (1950:Aug. 14) 144 
    Details
    ISSN: 0931-8658
    Thema: Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Wirtschaftstheorie
    Notizen: Einzelbesprechungen
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:4223-1950-013-01-000006
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  • 3
    Digitale Medien
    Digitale Medien
    Magnetic switching in cobalt films by adsorption of copper (1995)
    [s.l.] : Nature Publishing Group
    Nature 374 (1995), S. 788-790 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] We use Co films grown epitaxially on a Cu(lOO) single crystal with a slight miscut of 1.6° in the [110] direction-this produces a controlled step structure. These steps turn out to play a central part in the magnetic switching. To detect changes in the magnetization, we use spin-polarized ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/374788a0
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  • 4
    Digitale Medien
    Digitale Medien
    Influence of extracellur Ca2+ on endogenous Cl− channels in Xenopus oocytes (1995)
    Springer
    Pflügers Archiv 429 (1995), S. 820-824 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Xenopus oocyte ; External Ca2+ Cl− channel ; Voltage clamp ; Patch clamp
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Removal of Ca2+ from the external bath solution evoked marked depolarization and large currents (up to several microamperes) in voltage-clamped defolliculated oocytes of Xenopus laevis. The resulting current was not carried by a cation influx but was due to a huge Cl− efflux, which could be strongly inhibited by the Cl− channel blockers flufenamic acid and niflumic acid. Removal of Mg2+ or Ba2+ from the solutions had the same effects as removing Ca2+. The reversal potential of −12 mV also indicated that Cl− channels were responsible for the large currents. Patch-clamp studies revealed a single-channel slope conductance of 90 pS. During oocyte maturation these channels remained active. The half-maximal Ca2+ concentration of about 20 μM showed that quite low doses of extracellular Ca2+ profoundly influence the electrical properties of the oocyte membrane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00374806
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  • 5
    Digitale Medien
    Digitale Medien
    The Ca2+-induced leak current in Xenopus oocytes is indeed mediated through a Cl− channel (1995)
    Springer
    The journal of membrane biology 148 (1995), S. 263-275 
    Details
    ISSN: 1432-1424
    Schlagwort(e): Xenopus oocytes ; Cl− channel ; Divalent cations ; Leak current
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Defolliculated oocytes of Xenopus laevis responded to removal of external divalent cations with large depolarizations and, when voltage clamped, with huge currents. Single channel analysis revealed a Cl− channel with a slope conductance of about 90 pS at positive membrane potentials with at least four substates. Single channel amplitudes and mean channel currents had a reversal potential of approximately −15 mV as predicted by the Nernst equation for a channel perfectly selective for Cl−. Readdition of Ca2+ immediately inactivated the channel and restored the former membrane potential or clamp current. The inward currents were mediated by a Ca2+ inactivated Cl− channel (CaIC). The inhibitory potency of Ca2+ was a function of the external Ca2+ concentration with a half maximal blocker concentration of about 20 μm. These channels were inhibited by the Cl− channel blockers flufenamic acid, niflumic acid and diphenylamine-2-carboxylate (DPC). In contrast, 4,4′-acetamido-4′-isothiocyanatostilbene-2,2′-disulfonicacid (SITS), another Cl− channel blocker, led to activation of this Cl− channel. Like other Cl− channels, the CaIC was activated by cytosolic cAMP. Extracellular ATP inhibited the channel while ADP was without any effect. Injection of phorbol 12-myristate 13-acetate (PMA), a protein kinase C activating phorbol ester, stimulated the Cl− current. Cytochalasin D, an actin filament disrupting compound, reversibly decreased the clamp current demonstrating an influence of the cytoskeleton. The results indicate that removal of divalent cations activates Cl− channels in Xenopus oocytes which share several features with Cl− channels of the CLC family. The former so-called leak current of oocytes under divalent cation-free conditions is nothing else than an activation of Cl− channels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235044
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  • 6
    Digitale Medien
    Digitale Medien
    Zeit- und temperaturaufgelöste Röntgenpulverdiffraktometrie: Die Reaktion von (NH4)2SnF6 mit Ammoniak (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 617-623 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Formation of Sn(NH3)2F4 ; ammonolysis ; thermal decomposition of (NH4)2SnF6 ; time and temperature resolved x-ray diffractometry ; in situ x-ray diffractometry ; solid state reactions ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Time and Temperature Resolved in situ X-Ray Powder Diffractometry. The Reaction of (NH4)2SnF6 with AmmoniaThe thermal decomposition of (NH4)2SnF6 under an atmosphere of ammonia is reported. The complicated reaction paths were illucidated by time and temperature resolved in situ x-ray powder diffractometry. It is shown that this technique is a powerful tool to observe structural changes during reaction. It offers also a valuable access to thermodynamic and kinetic data for solid state and gas phase reactions. (NH4)2SnF6 decomposes under ammonia below room temperature to NH4F and amorphous SnF4 · x NH3. At a temperature of 80°C an intermediate product, (NH4)4SnF8, is formed, which decomposes at 140°C into (NH4)2SnF6 and NH4F. At 250°C (NH4)[Sn(NH3)F5] and Sn(NH3)2F4 are formed. The latter crystallises C-centered monoclinic with lattice constants a = 844.1(5) pm, b = 630.5(3) pm, c = 520.2(3) pm and b̃ = 114.02(7)°. At 330°C a further decomposition yields SnF2(NH2)2 with a C-centered monoclinic cell and lattice constants a = 1 069(7), b = 325.3(2), c = 504.8(3) pm and b̃ = 105.83(7)°. Finally above 500°C tin metal is formed.
    Notizen: Der komplizierte Verlauf der Reaktion von NH3 mit (NH4)2SnF6 wird mit der zeit- und temperaturaufgelösten Röntgendiffraktometrie verfolgt. Dabei erweist sich diese Methode als ideale Technik, um Veränderungen in der Struktur während der Reaktion aufzuzeichnen und ebenfalls thermodynamische und kinetische Daten zu gewinnen. (NH4)2SnF6 zersetzt sich schon bei 25°C unter trockenem NH3-Gas zu NH4F und einem röntgenamorphen Ammoniakat SnF4 · x NH3. Ab 80°C bildet sich (NH4)4SnF8 als Zwischenprodukt, das sich ab 140°C wieder in (NH4)2SnF6 und NH4F zersetzt. Bei 250°C entstehen NH4[Sn(NH3)F5] und Sn(NH3)2F4. Letzteres kristallisiert monoklin C-zentriert mit den Gitterkonstanten a = 844,1(5) pm, b = 630,5(3) pm, c = 520,2(3) pm und b̃ = 114,02(7)°. Ab 330°C erhält man SnF2(NH2)2. Aus dem Pulverdiffraktogramm ergibt sich eine C-zentrierte monokline Elementarzelle mit a = 1 069(7), b = 325,3(2), c = 504,8(3) pm und b̃ = 105,83(7)°. Bei noch höheren Temperaturen erfolgt die Zersetzung zu Zinn.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19956210419
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