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  • Springer  (24)
  • 2005-2009  (2)
  • 1980-1984  (9)
  • 1965-1969  (8)
  • 1925-1929  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Planta 79 (1968), S. 113-121 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. 28 marine Algen aus den Klassen der Chlorophyceen (5 Arten), Phaeophyceen (11) und Rhodophyceen (12) wurden auf das Vorkommen flüchtiger Amine untersucht. 2. Mit Hilfe papierchromatographischer und mikrokristallographischer Methoden konnten insgesamt 9 flüchtige Amine in Algen nachgewiesen werden: Methylamin (MA), Dimethylamin (DMA), Trimethylamin (TMA), Äthylamin (ÄA), Propylamin (PA), Isobutylamin (iBA), Isoamylamin (iAA), 2-Phenyläthylamin (PÄA) und das bisher aus der Natur nicht bekannte 2-Methylmercaptopropylamin (MMPA). 3. Weitverbreitet findet sich bei Algen Trimethylamin (in 23 von 28 untersuchten Arten), während Dimethylamin nur in 2 Arten sicher nachgewiesen werden konnte. Das natürliche Vorkommen von Methylamin ist nicht gesichert, da dieses Amin möglicherweise erst bei der Aufarbeitung aus instabilen Methylaminoverbindungen entsteht. 4. Primäre Amine kommen in Vertretern aller 3 Algenklassen vor, besonders verbreitet jedoch bei Rhodophyceen (7 von 12 Arten). Biogenetisch werden zumindest die primären Amine der Rhodophyceen, mit Ausnahme von Methylamin, durch enzymatische Decarboxylierung aus entsprechenden Aminosäuren gebildet.
    Notes: Summary Twenty-eight species of marine Chlorophyceae (5), Phaeophyceae (11), and Rhodophyceae (12) were examined for the occurence of simple volatile amines. The volatile alkaline constituents of the algal samples were extrated by alkaline steam destillation and separated and identified by paper chromatography and microcristallography. A total of 9 volatile amines were found to occur in the species so far examined: methylamine (MA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (ÄA), propylamine (PA), isobutylamine (iBA), isoamylamine (iAA), 2-phenylethylamine (PÄA), and 2-methylmercaptopropylamine (MMPA). MMPA has not previously been reported to occur in any other plant. The occurence of TMA is widespread in marine algae (23 of 28 sp.) whereas an occurrence of DMA could be demonstrated only in two species. MA, which was found in all algal samples, might be formed from labile methylamino-compounds in the course of preparation. Its coccurrence as a natural constituent of algae remains doubtful. Primary amines could be identified in species of each of the three classes of algae, but an especially widespread occurrence was found in Rhodophyceae. With the exception of MA the primary volatile amines, at least those of Rhodophyceae, arise biosynthetically from the corresponding amino acids by enzymatic decarboxylation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 54 (1967), S. 370-371 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 55 (1968), S. 346-347 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 25 (1981), S. 7-12 
    ISSN: 1432-0630
    Keywords: 06.30 F ; 07.62 ; 73.40 R
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Video response and mixing behaviour of metal-insulator-metal point contact diodes have been investigated for visible laser light. Thermally enhanced tunneling is shown to dominate the dc detection behavior of those diodes, while mixing of frequencies being more than several MHz apart is a more complex phenomenon involving thermal, field-and photo-assisted tunneling. In further experiments the potential of point contact diodes for optical heterodyne spectroscopy was examined. Two green laser lines of 122 GHz frequency difference were mixed with the second harmonic of an appropriate microwave frequency, generated simultaneously on the diode. The modestS/N ratio achieved has to be assigned to the different behaviour of metal-insulator-metal diodes in the visible and rf range.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 30 (1983), S. 189-193 
    ISSN: 1432-0649
    Keywords: 06.30 ; 42.65 ; 73.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Frequency differences of up to 900 GHz between two laser lines near 568 nm were measured by mixing laser light and harmonics of 90 GHz microwave radiation. The Schottky point contact diodes used consisted of tungsten tips onn-GaAs bases with different degrees of doping. The formation of the contacts and the sensitivity and frequency limitations of the device are discussed.
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  • 7
    ISSN: 1432-0649
    Keywords: 06.30F ; 07.62 ; 73.40R
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Frequency differences of up to 170 GHz between a cw dye laser and a krypton laser at 568 nm were measured by mixing laser and microware radiation with a metalinsulator-metal point contact diode. Beat signals are well above noise and there is still great potential for improvement when better microwave oscillators are used. From the measurements reported it follows that the diode can be used for determining still higher frequency differences of visible laser radiation.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 42 (1981), S. 241-244 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study the influence of the non-diagnonal terms in an easy-plane Heisenberg ferromagnet on the cross-section for inelastic neutron scattering from single spin-wave states. We show that these terms modify the wavevector dependence of the cross-section for unpolarized neutrons, and the created polarization. An appropriate experiment on CsNiF3, for example, should be a good test of these predictions, and would eventually clarify some uncertainties about the appropriate Boson Hamiltonian for an easy-plane ferromagnet.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 53 (1983), S. 117-142 
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The results of a detailed inelastic neutron scattering study of the spindynamics in CsNiF3 in an external magnetic field are presented. Results have been obtained for different combinations of the correlation function 〈S α Sα〉 (α=x, y, z) in order to analyse theH, T, q c-dependence of both, the central component and the spinwave scattering. These results cannot be explained by a multispin-wave theory alone, but it is necessary to introduce solitons in order to describe the experimental findings. It is found that under certain conditions the contribution from solitons and from two-spinwave processes have the same size. These results show that the spindynamics in this system in fields 2.5kOe〈H〈10kOe and5K≦...15K are similar to that in a sine-Gordon system. ForT〉15K this picture breaks down probably due to the finite size of the easy plane anisotropy energy.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 77 (1928), S. 68-76 
    ISSN: 1615-6110
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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