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  • 1990-1994  (3)
  • 1985-1989  (3)
  • 1960-1964
  • electroretinogram  (3)
  • Life and Medical Sciences  (2)
  • 75.50.-y  (1)
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Material
Years
  • 1990-1994  (3)
  • 1985-1989  (3)
  • 1960-1964
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Morphology and magnetic properties of ultrafine ZnFe2O4 particles (1990)
    Springer
    Applied physics 50 (1990), S. 13-16 
    Details
    ISSN: 1432-0630
    Keywords: 75.50.-y ; 76.80.+y ; 61.50.-f
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Well-crystallized ultrafine ZnFe2O4 particles of several nanometers in size have been prepared by the coprecipitation method, and their particle morphology and magnetic properties, especially at low temperatures, examined. Room-temperature X-ray diffraction, transmission electron microscopy, magnetization measurements at various temperatures from 300 K to 4.2 K, and Mössbauer spectroscopy at various temperatures from 300 K to 4.2 K, and at 4.2 K with a longitudinal magnetic field of 16.4 kOe applied have been employed. The formation of short-range and long-range magnetic order in small ZnFe2O4 particles above and below approximately 30 K is discussed. Below 30 K, the appearance of spontaneous magnetization and its hysteretic property is confirmed for small ZnFe2O4 particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323947
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of dopamine and haloperidol on the c-wave and light peak of light-induced retinal responses in chick eye (1987)
    Springer
    Documenta ophthalmologica 65 (1987), S. 87-95 
    Details
    ISSN: 1573-2622
    Keywords: c-wave ; centrifugal fibers ; chick retina ; dopamine ; electroretinogram ; haloperidol ; light peak
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The relation between dopaminergic cells (and centrifugal fibers), the electroretinogram (ERG) c-wave, and the light peak were electrophysiologically investigated by observing the effects of a retrobulbar conduction block and intravitreal injection of either dopamine or haloperidol on these retinal responses. The retrobulbar conduction block (1% lidocaine) caused a decrease in the amplitude of the c-wave and the light peak in newly hatched chicks. Injections (2–20 μl) containing dopamine (0.1–10 mM) or haloperidol (1.3–13 mM) were given intravitreously while the responses were recorded. Although intravitreous injection of saline for control resulted in no observable change in the responses, dopamine selectively augmented the c-wave of ERGs and the light peak, but not the a-, b-, and d-waves. Haloperidol decreased first the light peak and later the c-wave. The augmentation of the retinal responses by dopamine and their reduction by haloperidol was statistically significant. The estimated threshold concentration of dopamine in the vitreous cavity was 1–3.5 μM. Since in many species the interplexiform cells have been found to contain dopamine, we hypothesize that the modulatory effects on the c-wave and the light peak in this preparation may be due to a centrifugal feed-back loop which includes the interplexiform cells to the horizontal and bipolar cells and the horizontal cells to the cones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162724
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  • 3
    Electronic Resource
    Electronic Resource
    Osmotic pressure of the interstitial fluid obtained from neonatal chick eyes and its variation under light and dark adaptation (1985)
    Springer
    Documenta ophthalmologica 61 (1985), S. 79-89 
    Details
    ISSN: 1573-2622
    Keywords: adaptation ; aqueous humor ; electroretinogram ; intraocular fluids ; osmolarity ; vitreous humor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In experiments by Yoneyama et al. (1985) a hypertonic perfusing solution was used to record the c-wave from the isolated chick retina. We investigated whether the chick retina was surrounded by such hypertonic liquids. The following results were found: (1) the osmolarity of the subchoroidal humor was markedly higher than that of fluids from other areas of the eye; (2) the relative difference in osmolarity between both sides of the retina was 110–170 mOsmol in the light-adapted condition, whereas it was about 270 mOsmol in the dark-adapted condition; and (3) in the dark-adapted state the volume of the subchoroidal humor decreased about 40% but increased in osmolarity about 30–40%, whereas osmolarity of the subviteous humor decreased about 15–20 mOsmol. Results suggest the presence of an inward-directed pump mechanism for watersoluble components in the retina in addition to the proposed outward-directed pump mechanism of the pigment epithelium. The inward-directed pump may be more active in the dark-adapted state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00143219
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  • 4
    Electronic Resource
    Electronic Resource
    Gamma-aminobutyric acid- and picrotoxin-induced changes in c-wave and light peak of retinal potentials in the chick (1987)
    Springer
    Documenta ophthalmologica 65 (1987), S. 333-342 
    Details
    ISSN: 1573-2622
    Keywords: c-wave ; electroretinogram ; GABA ; light peak ; picrotoxin ; retinal standing potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Retinal potentials were recorded from the eyes of anesthetized and immobilized chicks by a standard direct current method. The amplitude of the electroretinogram (ERG) c-wave was measured 2 and 5 sec after the onset of the light stimulus, as indexes of the fast-rise c-wave (cF-wave) and the slow-rise c-wave (cs-wave), respectively. An intravitreal injection of gamma-aminobutyric acid (GABA) at an estimated intravitreal concentration of 10−9-10−7M resulted in an increase of the amplitude of the cs-wave, a less remarkable change in the a- and cF-waves, and a slight decrease in the b-wave. The light peak of the retinal standing potential increased in amplitude following GABA administration (10−7-10−4M). Following an intravitreal injection of picrotoxin (10−5-10−3M), the polarity of the cs-wave changed from positive to negative and a significant decrease and deformation in the light peak was observed. The amplitude of the a-wave, however, increased in the range of the higher dose, while that of the b- and cf-waves decreased markedly but no polarity reversal of the cF-wave was found. The results may suggest that the GABA-ergic synapse plays a significant role in production of the cs-wave and the light peak, along with that of the pigment epithelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149939
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  • 5
    Electronic Resource
    Electronic Resource
    Morphology of the teeth of adult caudata and apoda: Fine structure and chemistry of enamel (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 214 (1992), S. 341-350 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Representative functional teeth from Cryptobranchus alleghaniensis (Cryptobranchidae), Amphiuma means (Amphiumidae), Dicamptodon ensatus (Dicamptodontidae), Necturus maculosus (Proteidae), and Dermophis sp. (Costa Rica) (Caeciliidae) were prepared for transmission electron microscope and electron microprobe analysis of the trace elements of the enamel layer. The enamel layer of these species is very thin and the arrangement of enamel crystals variable. In particular, the outer part of the enamel layer in which hydroxyapatite elements (Ca, P) and trace elements (e.g., F, Fe, Mg) are concentrated, is most heavily mineralized. The concentrations and alignment of crystals in the outer and inner parts of the enamel layer differ among these species.The presence of collagen fibers in the inner part of the enamel layer of Cryptobranchus and Dermophis indicates that it is enameloid rather than true enamel. The presence of trace elements may be related to the pattern of mineralization of enamel or enameloid, as suggested for tetra-odontiform fishes by Suga et al. (J. Dent. Res. 68:1115-1123, 1989). © 1992 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052140309
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  • 6
    Electronic Resource
    Electronic Resource
    Histochemical study of jaw muscle fibers in the American alligator (Alligator mississippiensis) (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 211 (1992), S. 187-199 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Seven jaw muscles of the American alligator have been analyzed for histochemical characteristics of their fiber types: Musculus depressor mandibulae (MDM), M. pseudotemporalis (MP), M. adductor mandibulae posterior (MAMP), M. adductor mandibulae externus (MAME, profound and superficial portions), M. intramandibularis (MI), M. pterygoideus anterior (MPta), and M. pterygoideus posterior (MPtp). Classification of muscle fibers in previous studies has been based on (1) the staining properties of myosin ATPase after alkaline and acid preincubations and (2) the staining reactions for SDH, α-GPDH, PAS, and myosin ATPase after alkaline preincubations. In this study fiber types in one group of muscles (MP, MAMP, profound portion of MAME and MI) are classified (1) as type I, IIa, or IIb fibers, according to the system of Brooke and Kaiser (Arch. Neurol. 23:369-379, '70) or (2) as fast twitch glycolytic (FG), fast oxidative glycolytic (FOG), slow oxidative (SO), and tonic (few in number) fibers, according to the system of Putnam et al. (J. Exp. Zool. 214:303-309, '80). A second group of muscles (MDM, MAME superficial portion, MPta, and MPtp) reacted differently in similar histochemical tests and are classified, respectively, as (1) types 1, 2, 3 or (2) types A, B, C. We have distinguished the fiber types as red, intermediate, white, and tonic in analyses on muscle sections. The highest percentage of red and intermediate fibers is found in the MI. All three fiber types are approximately equal in superficial and medial portions of the MDM and the MPtp. Three muscles (MP, MAMP, and MAME) have the highest white fiber composition. These results indicate a correlation between the histochemical profiles of individual muscles and their functions during masticatory movements.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052110207
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    Paper (German National Licenses)
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