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  • 2000-2004  (2)
  • 1985-1989  (3)
  • 1975-1979  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 49 (1989), S. 343-347 
    ISSN: 1432-0649
    Keywords: 42.55F ; 42.60B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Design principles, construction and operation characteristics of a pulsed 469.4 nm He-Kr laser are described. The laser was operated in a 20 cm active length transverse hollow cathode discharge and was excited by 50 Hz repetition rate 0.1–1 ms duration square wave current pulses. Cataphoresis of Kr ions was found to play an important role in forming the laser pulse shape. By increasing the voltage a considerable increase of peak laser power occurred, the maximum power obtained was 80 mW. The sealed-off laser was operated using 400 μs, 4 A current pulses, pulsed laser power being 20 mW, average power 0.4 mW, respectively. The lifetime of the laser was 440 h, tube failure being due to gas cleanup caused by cathode sputtering.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 368 (2000), S. 384-388 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Δ4-3-Ketosteroids exhibit an intensive negative Cotton effect on the circular dichroism (CD) spectra in the wavelength range for the n-π* electronic transition (270–¶350 nm). With hydroxylamine hydrochloride, Δ4-3-ketosteroid compounds can be transformed into oxime derivatives. Following oxime formation, positive ellipticity with low intensity can be registered in this wavelength range. The quantitative determination of Δ4-3-ketosteroids is based on the considerable difference between the ellipticities before and after oxime formation. The difference ellipticity for the six ketosteroids examined (norethisterone, levonorgestrel, levonorgestrel acetate, methyltestosterone, testosterone phenylpropionate, nortestosterone phenylpropionate) varies linearly with the concentration in the interval 6 × 10–6–3 × 10–3 mol/L. The method can be well applied to determination of Δ4-3-ketosteroid contamination of norgestimate [(+)-13-ethyl-17-hydroxy-18,19-dinor-17α-pregn-4-en-20-yn-3-one oxime acetate]; 0.02–10% impurity can be measured.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 9 (1976), S. 241-250 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a étudié à l'aide d'un Derivatograph, sous diverses conditions, la réaction de mélanges binaires et ternaires des carbonates alcalins avec l'oxyde d'aluminium. L'identification des produits formés a été effectuée par diffraction des rayons X. Si les mélanges binaires et ternaires de carbonates contiennent du carbonate de lithium, il se forme toujours 1'α-métaaluminate de lithium, qui, à température plus élevée, se transforme en la formeγ. Si la carbonate de lithium est utilisé seul, on peut obtenir aussi l'ortho-dialuminate.
    Abstract: Zusammenfassung Die Reaktionen binärer und ternärer Alkalikarbonatmischungen mit Aluminiumoxid wurden mittels eines Derivatographen unter verschiedenen Bedingungen untersucht. Die Reaktionsprodukte wurden durch Röntgendiffraktion identifiziert. In Gegenwart Li2CO3-haltiger binärer und ternärer Karbonatmischungen war das Produkt stets α-Lithium-meta-aluminat, das bei höheren Temperaturen in dieγ-Form überging, während bei Einsatz von Li2CO3 auch Orthodialuminat erhalten werden konnte.
    Notes: Abstract Reactions of binary and ternary alkali metal carbonate mixtures with aluminium oxide were studied by means of a derivatograph under different conditions. Reaction products were identified by X-ray diffraction. In the presence of binary and ternary carbonate, mixtures containing Li2CO3 the product was alwaysα-lithium metaaluminate, transforming to theγ-form at higher temperatures, while using only Li2CO3 the orthodialuminate could be obtained too.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Molecular biology reports 12 (1987), S. 13-19 
    ISSN: 1573-4978
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Highly purified nuclear and cytoplasmic RNAs were obtained from Tetrahymena thermophila BVII containing only a minimal amount of cross-contamination. In the nuclear RNA fraction we have detected at least 6 distinct snRNAs. Some of the RNA species showed microheterogeneity. SnRNAs of Tetrahymena thermophila are very similar to rat snRNAs, as far as length is concerned. Our cytoplasmic small RNA fraction contained two RNAs, 7S and T7, reported recently (18) as nuclear, particularly nucleolar RNAs. Moreover, we could detect only one cytoplasmic small RNA species Tc1, Tc2 was not observed. Neither the nuclear nor the cytoplasmic small RNA species are degradation products of ribosomal RNA as was shown by Northern blotting and following hybridization with pGY17 containing the entire transcribed region of the ribosomal DNA of Tetrahymena thermophila.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0878
    Keywords: Cerebrospinal fluid-contacting neurons ; Monoclonal antibodies ; Opsin ; VIP ; Extraocular photoreceptors ; Ring dove ; Coturnix coturnix ; Anas platyrhynchos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cerebrospinal fluid-contacting (CSF) cells in both the septal and the tuberal areas in the brain of the ring dove are labeled by RET-P1, a monoclonal antibody to opsin that reacts with inner and outer segment membranes of rod photoreceptors in a variety of vertebrates. Immunoblot analysis of proteins from diverse brain regions, however, revealed bands of anti-RET-P1 immunoreactivity that did not correspond to opsin. Binding of RET-P1 to opsin-containing membranes, was not inhibited by membranes rich in muscarinic and β-adrenergic receptor proteins (red blood cells, heart, lung) taken from doves. RET-P1-immunoreactive CSF-contacting cells emit a dendritic process that penetrates the ependyma and ends in a knob-like terminal suspended in the ventricle. These cells also possess other processes that penetrate more or less deeply into the neuropil. Additionally, a band of labeled fibers occurs in the external layer of the median eminence. A double-label technique demonstrated that RET-P1-positive cells coexpress VIP-like immunoreactivity. VIP-positive cells in other brain areas are not RET-P1-positive.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-4854
    Keywords: wide gap amorphous silicon ; photoluminescence ; electroluminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A series of samples of hydrogenated amorphous silicon (a-Si:H) was prepared from silane diluted highly with He by the microwave electron-cyclotron-resonance PE CVD. Such a wide gap (E≥2.0 eV) a-Si:H emits room temperature photoluminescence (PL) in the visible region. We attempt to reveal the microscopic origin of this PL by monitoring variations of PL intensity vs frequency of infrared vibrations in the vicinity of 2100 cm−1. We find that oligosilanes -(SiH2)n- act as one type of possible luminescence centres. We report also on room temperature electroluminescence (EL) from p-i-n junctions. Surprisingly, and unlike p-i-n structures from standard a-Si:H, weak EL radiation with external quantum efficiency of the order of 10−5% is emitted under reverse bias only. EL and PL emission spectra resemble strongly each other, except high energy wing of the EL spectrum. This high energy widening indicates the participation of hot electrons in the EL excitation mechanism.
    Type of Medium: Electronic Resource
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