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  • 1990-1994  (47)
  • 1940-1944  (8)
  • 1920-1924
  • 1905-1909
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  • 1
    Electronic Resource
    Electronic Resource
    Two-dimensional Shubnikov–de Haas oscillations in modulation-doped CdTe/CdMnTe quantum-well structures (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 3010-3012 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For the first time clear evidence for two-dimensional Shubnikov–de Haas oscillations in modulation-doped CdTe/CdMnTe quantum-well structures is reported. The structures were grown by molecular-beam epitaxy using ZnBr2 as a novel source material for the n-type doping of II-VI epitaxial layers. From an analysis of the Shubnikov–de Haas oscillations a carrier density of 9×1011 cm−2 and an effective mass of 0.1 m0 could be deduced. Due to band filling the Fermi energy in the subbands is shifted above the conduction-band edge. This can be detected as a Stokes shift of absorption compared to photoluminescence recombination. From the Fermi energy shift the carrier concentration can be estimated, which agrees well with values determined by Hall-effect measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109173
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  • 2
    Electronic Resource
    Electronic Resource
    Gas source molecular beam epitaxy of FeSi2/Si(111) heterostructures (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 2271-2273 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial iron disilicide thin layers have been grown on silicon by gas source molecular beam epitaxy (GSMBE) in the temperature range 450–550 °C. Fe(CO)5 and SiH4 are used as sources for the silicide growth on a heated Si(111) surface. The growth phases are characterized in situ by means of high-resolution electron energy loss spectroscopy, ultraviolet and x-ray photoelectron spectroscopies. The formation of an epitaxial metallic γ-FeSi2 layer at the interface with the silicon substrate is revealed and no complete relaxation of this strained metastable interface layer is observed, as the growth proceeds with the semiconducting equilibrium β-FeSi2 phase. The coexistence in the GSMBE grown heterostructures of the metallic (CaF2) and semiconducting (orthorhombic) FeSi2 structures is confirmed by cross-section transmission electron microscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109411
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  • 3
    Electronic Resource
    Electronic Resource
    Cholecystokinin Mediates a Calcium Signal in Human Peripheral Blood Mononuclear Cells and Is a Co-mitogen (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 594 (1990), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1990.tb40509.x
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  • 4
    Electronic Resource
    Electronic Resource
    Structure of 1,2,3-tris(dimethylamino)cyclopropenylium aquatetrachlorooxoniobate(V) (1991)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 47 (1991), S. 1808-1811 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270191001245
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  • 5
    Electronic Resource
    Electronic Resource
    Structure of 1,2,3-tris(dimethylamino)cyclopropenylium hexachloroniobate(V) and hexachlorotantalate(V) (1992)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 795-798 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270191011903
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  • 6
    Electronic Resource
    Electronic Resource
    Structure of 1,2,3-tris(dimethylamino)cyclopropenylium hexachloroantimonate(V) (1992)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 912-913 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270191011940
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  • 7
    Electronic Resource
    Electronic Resource
    Negative Ionen in Braunschen Röhren und ihr Zusammenhang mit dem Oxydkathoden-Mechanismus (1943)
    Springer
    The European physical journal 121 (1943), S. 679-701 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Zusammenfassung Der von Oxydkathoden ausgehende negative Ionenstrahl wurde massenspektroskopisch analysiert und ein Vergleich der Ionenkomponenten verschiedenartiger Kathoden vorgenommen. Bei der Oxydkathode treten am intensivsten die H−-, CH−-, OH−-, O 2 − - und die Cl−-Ionen auf; daneben wurden noch 11 schwächere Ionenarten beobachtet. Aus der Schärfe der mit den negativen Ionen erzeugbaren Abbildungen wurde gefolgert, daß die Ionen einen einheitlichen Entstehungsort haben. Als solcher wurde für die meisten Ionen die Kathodensubstanz ermittelt, einzig für die OH−-Ionen kommt als Herkunftsort nicht nur die Kathodensubstanz, sondern auch der Gasraum in Frage, indem OH2-Moleküle aus dem Gasraum auf die Kathodenoberfläche geraten und von dort als negative OH−-Ionen wieder emittiert werden. Der Zusammenhang zwischen der O 2 − -Emission und der Elektronenemission der Kathode wurde während der Aktivierung untersucht und durch eine Vorstellung vom Formierprozeß gedeutet: Danach besteht die Aktivierung der Kathode darin, daß Ballonen auf Grund der thermischen Dissoziation im BaO ihren regulären Platz im BaO-Gitter verlassen und an bevorzugten Stellen adsorbiert werden, wodurch sie den Charakter einer elektronenliefernden „Störstelle“ annehmen. Es wurden ferner Annahmen über den Transport der negativen Ionen vom Herkunftsort in der Kathodensubstanz bis zur Kathodenoberfläche gemacht: Während die O−-, OH−-, Cl−-Ionen durch die Ba O-Kristallite hindurch zur Kathodenoberfläche wandern, muß für die CH−- und die C 2 − -Ionen auf Grund ihres Verhaltens eine Oberflächenwanderung längs der Kristallit-Grenzflächen zur Kathodenoberfläche angenommen werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01339166
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  • 8
    Electronic Resource
    Electronic Resource
    Synthese und Reaktionen von 2-Arylhydrazono-2-cyan-N,N-dialkyl-acetamidinen (1991)
    Springer
    Monatshefte für Chemie 122 (1991), S. 195-207 
    Details
    ISSN: 1434-4475
    Keywords: 5-Dialkylamino-2-aryl-1,2,3-triazoles ; 4-Amino-2,6-dioxo-tetrahydropyrid-3-yl-pyridiniumchloride ; 2-Arylhydrazono-2-cyan-N-chloracetylacetamide ; Arylhydrazono-2-cyan-N,N-dialkylacetamidines ; Arylhydrazonomalononitriles ; 4-Imino-5-arylazo-6-dialkylamino-1,4-dihydropyrimidines ; 13C-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The title compounds3 were synthesized by reaction of arlyhydrazono-malononitriles1 with secondary amines and used for subsequent cyclization reactions. Thus,3 undergoes cyclooxidation by treatment with CuSO4/pyridine to form the 5-dialkylamino-2-aryl-1,2,3-triazolo-4-carbonitriles4. From4 a and hydrazine hydrate/DMF the 4-(1,3,4-triazolyl-5)-1,2,3-triazole5 c is obtainable. The chloroacetylation of3 is accompanied by hydrolysis of the amino group to yield the arylhydrazono-N-chloracetyl cyanoacetamides6. The quaternisation of6 with pyridins is followed by the Thorpe cyclization to form the 4-amino-5-arylazo-6-hydroxy-3-pyridinio-pyrid-2-on-chlorides8, useful as cationic dyes. The reaction of3 with trichloroacetonitriles yields the 5-arylazo-4-imino-2-trichlormethyl-1,4-dihydropyrimidines10 a–c which can be converted into the 5-arylazo-2-hydrazino-pyrimidine derivatives10 d–f. From10 d the 6-phenylazo-triazolo[4,3-a]pyrimidine derivative11 is obtainable. From3 and phenylisothiocyanate the 5-arylazo-4-imino-1,4-dihydropyrimidin-2-thiones12 arise. The structures were investigated by13C-NMR-spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809365
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  • 9
    Electronic Resource
    Electronic Resource
    Sealing of bore-holes in Si crystals by epitaxial overgrowth below 560° C (1990)
    Springer
    Applied physics 50 (1990), S. 583-585 
    Details
    ISSN: 1432-0630
    Keywords: 81.10.D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Liquid phase epitaxy (LPE) is applied to seal small bore-holes (diameter 250–400 μm) in Si crystals by lateral overgrowth. The overgrowth layers have a typical thickness of 20 μm, are mechanically stable and gas-tight. Using Ga as solvent for the LPE process the overgrowth can be performed at temperatures as low as 560°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323451
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  • 10
    Electronic Resource
    Electronic Resource
    Histochemical and biochemical determination of calcium in salivary glands of cat (1993)
    Springer
    Histochemistry and cell biology 100 (1993), S. 155-159 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Although feline salivary glands have been used in investigations on secretion and microlithiasis and both processes involve calcium, nothing is known about its distribution in these glands. Therefore we have demonstrated the presence of calcium by a histochemical technique using glyoxal bis(2-hydroxyanil) and a biochemical technique using dry ashing. The histochemical technique stained serous acinar cells weakly and rarely found mucous acinar cells strongly in the parotid gland, mucous acinar cells moderately to strongly and serous acinar cells weakly in the sublingual gland, and central and demilunar acinar cells moderately to strongly in the submandibular gland. The biochemical technique revealed less calcium in the parotid than in the submandibular and sublingual glands. Both techniques revealed a decrease of calcium in submandibular and sublingual glands following parasympathetic stimulation. The histochemical distribution of calcium, which corresponds to that of acinar secretory glycoprotein, and the loss of calcium following parasympathetic stimulation, which causes release of secretory granules, indicate the presence of calcium in secretory granules. The concentration of calcium in the different types of acinar cell corresponds to the acidity of the secretory glycoprotein and suggests that calcium is present as a cationic shield to allow the condensation of polyionic glycoprotein in secretory granules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00572902
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