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  • 1970-1974  (12)
  • 1935-1939
  • 1974  (12)
  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 39 (1974), S. 1685-1688 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 35 (1974), S. 83-103 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two hundred and eighty-five hours of solar data obtained from the University of Iowa 2 cm radiometer during 1968–1969 were analyzed for evidence of periodic structure related to the 5 min periodic chromospheric oscillations detected in optical line emissions. A power spectral analysis of the data failed to show any statistically significant (〉 96 % confidence) periodic activity in the frequency range 1–15 mHz (periods of 1–16 min) for data organized according to solar activity in Hα, soft solar X-rays (2–12 Å), and several microwave frequencies (3–15 GHz). A small shift in power from low to higher frequencies in the power spectrum of the 2 cm data was found to be correlated with Hα and X-ray activity. This power shift is attributed to a relative increase in chromospheric turbulence at altitudes common to Hα, X-ray, and 2 cm emission. Consistent statistical analyses of previous works reporting evidence for oscillations at microwave and extreme-ultraviolet frequencies indicate that confidence in these previous results is marginal. A model for chromospheric oscillation bursts in quiescent supergranules is incorporated into a statistical analysis of the power spectrum detectability of the oscillations to understand the negative results obtained.
    Type of Medium: Electronic Resource
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  • 3
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    Boston : Periodicals Archive Online (PAO)
    Business History Review. 48:1 (1974:Spring) 117 
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  • 4
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    Unknown
    Boston : Periodicals Archive Online (PAO)
    Business History Review. 48:4 (1974:Winter) 451 
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  • 5
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Temperature sensitivity of growth and transformation by certain early Rous sarcoma virus mutants correlates with thermolability of their virion-associated DNA polymerase. The enzyme is therefore encoded by viral RNA and is required for provirus ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 112 (1974), S. 265-273 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The shape of a bent flexible wire is shown to be identical to the shape of constant absolute vorticity trajectories in the atmosphere. This shape is characteristic of river meanders and is shown to be characteristic of meanders in the jet stream and the Gulf Stream. Several examples are considered and shown to match extremely well with the ‘ideal’ curves.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 36 (1974), S. 109-115 
    ISSN: 1432-2072
    Keywords: Frontal Cortical Ablations ; d-Amphetamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats trained to bar-press on a FI 15 sec schedule for water reinforcement were administered various doses of d-amphetamine (0.25–4.0 mg/kg) both before and 6–8 weeks after bilateral ablation of frontal cortex. Preoperatively, low doses (e.g. 0.25–0.5 mg/kg) of (d-amphetamine increased responding and high doses (e.g. 2.0–4.0 mg/kg) of d-amphetamine depressed responding. Postoperatively, frontal rats showed larger facilitatory effects in response to low doses of d-amphet-amine but lesser depressant effects in response to high doses of d-amphetamine; the whole dose-response curve was generally shifted higher by the frontal lesions. These results indicate that frontal lesions differentially influence mechanisms mediating two different actions of d-amphetamine.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 90 (1974), S. 275-295 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The hypothesis advanced by James W. Truman to explain the photoperiodically regulated circadian rhythm of adult eclosion in a Saturniid moth has been modified and extended to form the basis of a proposed Developmental Determination Model. This model postulates the synthesis of a hypothetical substance (S) and the kinetics of its metabolism in the presence or absence of light energy. The relationship of scotophase duration to the temporal occurrence of postulated “determination response thresholds” was estimated in the terms of the hypothetical model. The temporal position of a postulated “Determination Gate” was also approximated in terms of the model system. The characteristics of the proposed model were designed to be consistent with the observed effects of different 24-hour photoperiods on the incidence of diapause among larvae of the European corn borer,Ostrinia nubilalis. The proposed Determination Model was shown to be capable of generating all four types of photoperiodic diapause reponse curves reported in existing literature.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 90 (1974), S. 297-310 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A model formulated to provide a theoretical basis for the interpretation of developmental responses to photoperiod is presented. Experimental data on the photoperiodic determination of diapause and non-diapause in the European corn borer,Ostrinia nubilalis, were used to estimate the required characteristics of the model. The prototype model, presented in the previous paper (I) of this series (Beck, 1974) postulated the existence of a photoperiodically regulated time period during which developmental alternatives are determined; this time period was called the Determination Gate (DG). The present study includes determination of the characteristics and kinetics of a model system [the (P)-system] underlying the temporal placement of DG. The effects of photophase duration on subsequent DG placement are also presented.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 149 (1974), S. 21-41 
    ISSN: 1432-0878
    Keywords: Compound eye ; Musca domestica ; Ommatidia ; Optic cartridge ; Basement membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The compound eye of the housefly, from lens to first optic neuropile (lamina ganglionaris) was examined with a scanning electron microscope. Key findings are as follows: The pseudocone cavity is enclosed by six corneal pigment cells. The nuclei of the six cells are firmly anchored to the underside of the lens and portions remain after lens delamination from the pseudocone cavity. An eccentrically-positioned, short photoreceptor cell was observed near the region where the inferior central cell initiates its rhabdom. This eminence may represent that cell's soma. The basement membrane is revealed as a two-tiered, fibrous layer with ovoid fenestrations. Each opening is sealed with a diaphragm perforated by eight retinular axons and a trachea. Conjoined distal surfaces of the satellite glial cells form a membrane-like barrier immediately underlying the basement membrane. Monopolar somata from the lamina are covered with glial cells which possibly make more intimate contact with the somata through miniscule projections. Optic cartridges with monopolar interneurons were noted. Spherical to slightly biconcave processes of these interneurons contact retinular axons. Very fine (1000 Å) filaments interweave among and contact lateral processes. Further implications are discussed as they relate to observed structures.
    Type of Medium: Electronic Resource
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