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  • 1980-1984
  • 1975-1979
  • 1970-1974  (15)
  • 1974  (15)
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Materialart
Erscheinungszeitraum
  • 1980-1984
  • 1975-1979
  • 1970-1974  (15)
Jahr
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  • 1
    Digitale Medien
    Digitale Medien
    SODIUM-DEPENDENT EFFLUX AND EXCHANGE OF GABA IN SYNAPTOSOMES (1974)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 23 (1974), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract— The influx and efflux of [3H]GABA were investigated in synaptosomes. Two efflux components were detected. The first, termed spontaneous efflux, was not affected by the external sodium chloride concentration. The second, termed GABA-stimulated efflux, was observed when low levels of GABA were added to the incubation medium and was found to require external sodium chloride. The rate of spontaneous efflux at 0°C was about 37 per cent of the rate at 27°C but both GABA-stimulated efflux and GABA influx were completely inhibited at 0°C. The stimulation of efflux by external GABA followed simple Michaelis–Menten kinetics with respect to external GABA. The concentration of external GABA required for half-maximal stimulation was 4·9 ± 1·4 μm and the Vmax for efflux was 1·0 ± 0·6 nmol. min-1.mg-1 of protein. A similar stimulation of efflux was observed with GABA analogue l-2,4-diamino-butyric acid which is a competitive inhibitor of influx. The concentration of external l-2,4-diaminobutyric acid required for half-maximal stimulation of efflux was 51 ± 12 μm and the Vmax for efflux was 0·8 ± 0·5 nmol.min-1.mg-1 of protein. Since the sodium-dependency, temperature sensitivity, and kinetic properties of the GABA-stimulated efflux system were similar to the influx system, GABA-stimulated efflux was attributed to carrier-mediated exchange diffusion. Measurement of efflux and influx in the same preparation showed there was a net efflux when total fluxes were considered and that the exchange ratio (influx to GABA-stimulated efflux) was 0·9 when carrier-mediated fluxes were considered. The effect of the temperature of the fluid used to rinse synaptosomes collected on filters in influx experiments was investigated. There was no detectable difference in measured values of influx between samples rinsed with cold fluid (0°C) and warm fluid (27°C). The endogenous GABA content of synaptosomes was found to be 20·3 ± 2·5 nmol GABA per mg of protein. From this value, the cytoplasmic concentration of GABA in synaptosomes was estimated to be a maximum of 40 mm. About 5 per cent of total cerebral cortical GABA was found in the synaptosomal fraction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.1974.tb10750.x
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  • 2
    Digitale Medien
    Digitale Medien
    Asquith, Bonar Law and the First Coalition (1974)
    Cambridge : Cambridge University Press
    The @historical journal 17 (1974), S. 813-836 
    Details
    ISSN: 0018-246X
    Quelle: Cambridge Journals Digital Archives
    Thema: Geschichte
    Notizen: The debate over the reasons for the establishment of the Coalition Government in May 1915 continues to resist a conclusion despite the use of new collections of private papers. Unless the papers not so far available to researchers happen to contain an unusually convincing letter in the hand of one of the three mens responsible for the decision, this question seems well placed to defy solution indefinitely. It is the purpose of this article, therefore, to attempt a clarification of the immediate causes by taking a slightly wider perspective than is normally done. In this way one can recognize the Coalition of 1915 for what in essence it was, an attempt to avoid a ‘ Khaki Election ’ on the pattern of 1900.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1017/S0018246X00007925
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  • 3
    Digitale Medien
    Digitale Medien
    Turtle drift (1974)
    [s.l.] : Nature Publishing Group
    Nature 250 (1974), S. 351-351 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] SIR,?It occurs to me that the origin of the peculiar migration pattern of the green turtle, Chelonia mydas may be otherwise than suggested by Carr and Coleman1. They argued that since the early Cainozoic certain turtles have inherited a tendency to swim a particular WNW?ESE path from Brazil to the ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/250351a0
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  • 4
    Digitale Medien
    Digitale Medien
    The response of Gymnodinium breve to municipal waste materials (1974)
    Springer
    Marine biology 24 (1974), S. 223-228 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The response of the unarmored dinoflagellate Gymnodinium breve, which is the causative organism in catastrophic fish kills along the Florida Gulf coast, to enrichment with selected inorganic nutrients, municipal waste materials, and various detergent components has been determined. The biostimulatory effects of the various enrichments were determined by a modification of the Provisional Algal Assay Procedure of the Joint Industry/Government Task Force on Eutrophication. Inorganic nutrients (orthophosphate, nitrate, and ammonia) were added individually and in combination, and the results were compared to equivalent enrichments with the effluent from a secondary sewage-treatment plant. The maximum cell population, Nmax, attained could be increased 3-fold by the sew-age-treatment plant effluent or by the equivalent combination of inorganic nutrients; individually, however, the inorganic nutrients had no pronounced effect on maximum cell population, Nmax (except for a 30% increase produced by slight orthophosphate enrichment). The results of these studies indiccate that, at concentrations of orthophosphate typical of Florida coastal waters (ca. 0.10 ppm), the growth-promoting potential (as reflected by Nmax) of the medium was a linear function of the ammonia-nitrogen concentration (0.01 to 0.11 ppm). The sewage-treatment plant effluent was presumably low in detergent phosphate, having been obtained from a treatment plant some 6 months after the enactment of a ban on phosphate-containing detergents. Additions of orthophosphate or detergent-phosphate to the treatment-plant effluent did not significantly increase the observed biostimulatory effect of the waste material.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00391897
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  • 5
    Digitale Medien
    Digitale Medien
    Effect of selected surfactants on the growth characteristics of Gymnodinium breve (1974)
    Springer
    Marine biology 28 (1974), S. 253-259 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Growth studies of Gymnodinium breve in nutrient enriched and unenriched medium showed that anionic surfactants have the most deleterious effects on initial response, growth rate, and maximum cell numbers as compared with cationic and non-ionics. Degradation rates were determined, and the surfactant with the most favorable rate (C12 alkyl-benzene sulfonate) was further tested. The growth constant, K e , and maximum cell number, N max , decreased with increasing amount of surfactant added to G. breve cultures (enriched sea-water media); a minimum was observed at 12.5 ppb. Above this concentration the values of K e and N max increased to approach control values. This profile was ascribed to the formation of surfactant micelles that are ineffective. The surfactant produced mortality of G. breve (90% mortality versus 12% in untreated samples) in natural red-tide samples, but other algae and zooplankton were undisturbed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00388492
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  • 6
    facet.materialart.
    Unbekannt
    Length Constraints, Reduction Rules, and Holophrastic Processes in Children's Word Combinations (1974)
    New York : Periodicals Archive Online (PAO)
    Journal of Memory and Language. 13:4 (1974:Aug.) 448 
    Details
    ISSN: 0749-596X
    Thema: Psychologie
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:b180-1974-013-04-000010
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  • 7
    Digitale Medien
    Digitale Medien
    Representations of coronal magnetic fields including currents (1974)
    Springer
    Solar physics 36 (1974), S. 345-350 
    Details
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Coronal electric currents are superposed on the calculated large-scale current-free (potential) magnetic field of the solar corona and the new magnetic configurations are mapped. The results indicate that relatively large coronal electric currents are required before significant topological deviations from the potential magnetic field configuration can be noticed. Thus any agreement between coronal observations and calculated potential magnetic field configurations should not be interpreted to mean that coronal electric currents are necessarily absent or insignificant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00151204
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  • 8
    Digitale Medien
    Digitale Medien
    A multi-slit spectrograph and Hα Doppler system (1974)
    Springer
    Solar physics 37 (1974), S. 343-350 
    Details
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A multiple entrance slit spectrograph was built for time-lapse photography of the spectra of flares and other transient solar phenomena. This spectrograph employs narrow-band filters to limit the wavelength range of the spectrograph to several angstroms centered at Hα or other spectral lines. The passband of the filter, and the dispersion of the spectrograph determine the number of parallel slits through which light may be passed to achieve multiple adjacent spectral displays. By using a 7 Å filter, a dispersion of 10.8 Å mm−1, and 35 mm film, adjacent Hα spectra are imaged from 30 parallel slits. A system of mirrors and relay lenses transfers the slitjaw image to the same film plane as the spectral image. A 2 frame camera is used to simultaneously record both images on adjacent frames. Filtering of the reference spatial image to 1.0 Å allows the observer to see the position of the slits relative to the Hα centerline structure and to match the brightness of the spatial image to the spectral display. A polarizing beamsplitter, prior to the slits, provides a prefiltered second solar image to a narrow band Hα Doppler filter for simultaneous photography in the wings of the Hα line. The multislit monochromatic spectrograph and Hα Doppler system constitute a flexible instrument in which components may be substituted to achieve different passbands width, image scales, dispersions and corresponding numbers and spacings of adjacent spectra at a selected wavelength.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00152493
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  • 9
    Digitale Medien
    Digitale Medien
    The large-scale solar magnetic field (1974)
    Springer
    Solar physics 39 (1974), S. 3-17 
    Details
    ISSN: 1573-093X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The large-scale photospheric magnetic field, measured by the Mt. Wilson magnetograph, has been analyzed in terms of surface harmonics (P n m )(θ)cosmφ and P n m (θ)sinmφ) for the years 1959 through 1972. Our results are as follows. The single harmonic which most often characterized the general solar magnetic field throughout the period of observation corresponds to a dipole lying in the plane of the equator (2 sectors, n = m = 1). This 2-sector harmonic was particularly dominant during the active years of solar cycles 19 and 20. The north-south dipole harmonic (n = 1, m = 0) was prominent only during quiet years and was relatively insignificant during the active years. (The derived north-south dipole includes magnetic fields from the entire solar surface and does not necessarily correlate with either the dipole-like appearance of the polar regions of the Sun or with the weak polar magnetic fields.) The 4-sector structure (n = m = 2) was prominent, and often dominant, at various times throughout the cycle. A 6-sector structure (n = m = 3) occasionally became dominant for very brief periods during the active years. Contributions to the general solar magnetic field from harmonics of principal index 4 ⩽ n ⩽ 9 were generally relatively small throughout this entire solar cycle with one outstanding exception. For a period of several months prior to the large August 1972 flares, the global photospheric field was dominated by an n = 5 harmonic; this harmonic returned to a low value shortly after the August 1972 flare events. Rapid changes in the global harmonics, in particular, relative and absolute changes in the contributions of harmonics of different principal index n to the global field, imply that the global solar field is not very deep or that very strong fluid flows connect the photosphere with deeper layers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00154967
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  • 10
    Digitale Medien
    Digitale Medien
    Cosmogony of the asteroidal belt (1974)
    [s.l.] : Nature Publishing Group
    Nature 250 (1974), S. 634-636 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] If a rotating body has an axisymmetric dipole field and is surrounded by a plasma, and if the electrical conductivity of the body and of the plasma is infinite, the plasma will rotate with the same angular velocity ? as the body; the magnetic field lines are 'frozen-in'. This idealised model is, ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/250634a0
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