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  • Electronic Resource  (7)
  • 1990-1994  (7)
  • 1992  (7)
  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 8 (1992), S. 2913-2920 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1440
    Keywords: Tobacco-specific nitrosamines ; Toxicokinetics ; Genotoxicity ; Systemic effects ; Primary cells ; Detection of DNA damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ex vivo model to detect nonspecific DNA damage in different rat tissues has been developed and employed to study systemic properties of tobacco-specific N-nitrosamines. One hour after treatment of rats with the carcinogens, primary, intact cells were isolated from various organs. Viability of the cells was monitored by trypan blue exclusion. Genotoxicity was determined by alkaline elution, in situ nick translation or microgel electrophoresis. We found that oral application of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces genotoxic effects in the liver (3.125–50 mg/kg), whereas N-nitrosonornicotine (NNN) is only moderately active (50–100 mg/kg). Furthermore, oral administration of NNK, NNN, and of N-nitrosodimethylamine (NDMA), induces DNA damage in the nasal cavity. In peripheral blood lymphocytes genotoxicity of NDMA (〈 2 mg/kg), but not of NNK (50 mg/kg), was observed. NDMA and NNK are just as genotoxic in the liver when administered by inhalation as orally (effective doses: 0.1–1 and 50 mg/kg, respectively). For human cancer, these results indicate that in addition to the susceptibilities in local organs (oral cavity after snuff dipping and lung after tobacco smoke inhalation), these nitrosamines also pose a risk systemically for more remote organs.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 79 (1992), S. 422-423 
    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
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The stable carbon and oxygen isotopic compositions of the massive coralPorites lobata collected from the Gulf of Eilat, Red Sea, in May 1987 were measured along the vertical growth axis. The isotopic compositions show annual periodicity. The variations along the isotopic profile, compared with the X-radiography, indicate that the high-density bands are enriched in18O and deposited during the season of lowest water temperature (winter). In contrast, the low-density bands are depleted in18O and deposited during the warmest seawater temperatures (summer). The stable carbon and the oxygen isotopic ratios are negatively correlated with a shift in phase. During the season of higher water temperatures and light intensity values (summer), the skeleton is depleted in18O and enriched in13C and vice versa for the winter time. The shift between the carbon and the oxygen isotopic curves reflects the shift between the seasonal light intensities and seasonal temperature variations in the shallow water. The oxygen isotope ratio was used to detect the seasonal variations in seawater temperatures. The coral aragonitic skeleton is depleted in18O compared to apparent equilibrium with ambient seawater. The disequilibria range from (ca.) -3.10‰ to -3.50‰ with an average value of 3.40‰. The isotope fractionation behavior during skeleton precipitation is discussed in light of the environmental variables.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1615-6110
    Keywords: Hepaticae ; Monocleales ; Monoclea ; Chemotaxonomy ; flavonoids ; bisbibenzyls ; terpenoids ; morphology ; sporophyte ; antheridial receptacle ; geographical variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recognition of two different species in the liverwort genusMonoclea Hook. (monotypic orderMonocleales), viz.M. forsteri Hook. in New Zealand andM. gottschei Lindb. in the New World, is supported by characteristics of the sporophyte, antheridial receptacle and secondary metabolites.M. gottschei produces the greatest variety of flavonoids and the largest amount of bisbibenzyls ever encountered in a liverwort. In contrast,M. forsteri is poor in secondary metabolites. Two allopatric subspecies are recognized inM. gottschei, based on characteristics of the antheridial receptacle: subsp.gottschei in Chile (Valdivian region, Juan Fernandez Is.) and subsp.elongata Gradst. & Mues, subsp. nova, in tropical America. The exclusive occurrence inMonoclea of glucuronide and galacturonide flavone glycosides and the fact that capsule dehiscence may take place before full elongation of the seta are new arguments in support of the placement ofMonocleales in theMarchantiidae.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-601X
    Keywords: 03.30.+p ; 29.20.Dh ; 32.90.+a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have performed for the first time precision spectroscopy on a coasting fast7Li+ ion beam in a storage ring. The ion beam moving with 6.4% speed of light was first electron cooled and then merged with two counterpropagating laser beams acting on two different hyperfine transitions sharing a common upper level (λ-system). One laser was frequency locked to thea 3 127J2 hfs frequency component established as a secondary frequency standard at 514 nm. The second laser was tuned over theλ-resonance, which was recorded relative to127J2 hfs components. This experiment is sensitive to the time dilation in fast moving frames and will lead to new limits for the verification of special relatively. The present status of the experiment and perspectives in accuracy are discussed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract At the TSR cooler ring at Heidelberg, laser studies were carried out using singly charged lithium and beryllium ions. Laser spectroscopy of relativistic lithium ions (v=0.04c) yielded signals with a narrow linewidth, suitable for an experimental test of special relativity. A dramatic reduction of the beam temperature, as defined by the longitudinal velocity spread, was achieved via laser cooling in both cases. At the ion energies available at ESR it will become possible to prepare and store bare ions up to U92+. Electron cooling was succesfully demonstrated for hydrogen-like Bi82+ ions, where a laser experiment is scheduled to study the ground-state hyperfine splitting.
    Type of Medium: Electronic Resource
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