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  • Springer  (121)
  • 1970-1974  (87)
  • 1960-1964  (21)
  • 1950-1954  (13)
  • 1920-1924
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  • 1
    Digitale Medien
    Digitale Medien
    The nesting of the Pacific ridley turtle Lepidochelys olivacea on Playa Nancite, Costa Rica (1974)
    Springer
    Marine biology 24 (1974), S. 97-107 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A study of the nesting of the Pacific ridley turtle Lepidochelys olivacea was undertaken in Costa Rica on Playa Nancite — one of two beaches on which the authors had, the previous year, discovered large nesting aggregations of this species. During the 3 1/2-month period of this study, approximately 288,000 turtles nested on the 1300 m-long beach. About 99% of these nested during 3 periods of mass-nesting (arribadas). The predictability of the arribadas was investigated by observing and recording environmental parameters with which they may be correlated. The mass-nesting phenomenon, aspects of nesting behavior, and the adaptive advantages of mass-nesting are discussed. During the period of study, nearly 2,000 turtles were tagged, 102 of which were subsequently recovered. Carapace lengths and widths of 251 tagged turtles were measured. The emergence of hatchlings was recorded daily and, from these data, the incubation period and an indication of egg and hatchling survival was obtained. The activities of the various predators on eggs, hatchlings, and adults are described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00389343
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Notes on the Nerita (Archaeogastropoda) populations of Aldabra Atoll, Indian Ocean (1971)
    Springer
    Marine biology 9 (1971), S. 290-299 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nerita undata, N. plicata, N. polita, N. albicilla and N. textilis are common intertidal gastropods on Aldabra Atoll. Each species prefers a different level on the shore and/or different degrees of exposure to wave action. Patterns of zonation, population size-frequency structure and biomass are given. N. undata exhibits 2 distinct ecophenotypes. Normal types occur on expsed to moderately sheltered shores but are replaced by ‘type B’ in extremely sheltered conditions. Differences in shell morphology and population structure are also noted. Foraging by all species was confined to hours of darkness, generally at low tide. Activity of N. polita was induced slightly on overcast days. N. undata and N. textilis are cryptically coloured and often visible during the day. N. plicata is conspicuous, but is protected by a strong shell. N. polita and N. albicilla are often brightly and variably coloured, but both are concealed during daylight. No Nerita were found infected with trematodes, suggesting that the degree of infection was extremely low. Habitats of the Aldabran Nerita are compared with 3 species on Barbados, West Indies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00372823
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Cardiac and respiratory responses in the climbing perchAnabas testudineus (1973)
    Springer
    Journal of comparative physiology 84 (1973), S. 205-226 
    Details
    ISSN: 1432-1351
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The heart rate ofAnabas is about 40 beats/min when breathing water and air. Tachycardia occurs as the fish takes an air breath and the rate declines as the breath holding continues but water breathing stops. Bradycardia is observed during this later phase. By the time the next air breath is taken, the heart rate has dropped to 15–30 beats/min. The heart rate of a fish breathing normoxic water but prevented from surfacing is about 42/min. Bradycardia occurs in hypoxic water under similar conditions. Tachycardia is observed in active fish when breathing hypercarbic water and air. On exposure to air bradycardia is found in resting fish but tachycardia occurs during activity. In air,Anabas usually repeats a breath when the heart rate drops to 15–25 beats/min. Tachycardia occurs immediately following an air breath. Heart rate then returns over a period of 3–6 mins to the normal resting level of 30 beats/min. The gas composition of the suprabranchial chambers has been measured and its relationship with the occurrence of an air breath, tachycardia and bradycardia is described. The experimental results are discussed in relation to the anatomy of the blood supply to the respiratory organs. The possible role of respiratory gases and pH in the control of breathing and perfusion is also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00697607
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Annual production of two Nova Scotian populations of Nucella lapillus (L.) (1972)
    Springer
    Oecologia 8 (1972), S. 356-370 
    Details
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary One population of Nucella lapillus, under conditions of food shortage, decreased in biomass with an annual production of 5.5 kcal per m2. The second population, with plenty of food, gained biomass and the annual production was 16.7 kcal per m2. Individuals grew faster, while attaining sexual maturity and terminating growth at a larger size in the second population. In both populations, energy produced as gametes exceeded the energy produced due to growth. A 2.56 cm female was estimated to produce 46.6 egg capsules (about 1 kcal) a year but the output of males was unknown and assumed to be half that of females. The sex ratio was equal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00367538
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Some observations of sea turtle nesting activity in Costa Rica (1972)
    Springer
    Marine biology 16 (1972), S. 297-309 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Low level aerial observations were used to obtain synoptic records of the distribution of sea turtle nesting activity along both coasts of Costa Rica. Pertinent environmental information was simultaneously recorded including beach characteristics, river effluents, and evidence of coastal currents. Other correlative information was obtained from detailed maps, current charts, and climatological data. On the Caribbean coast, as expected, green turtle (Chelonia mydas) nesting was concentrated on the beaches between the Tortuguero and Parismina Rivers. On the Pacific coast, two major nesting beaches for the Pacific ridley Lepidochelys olivacea were found, each having over 100 thousand turtles aggregated offshore during the peak period between September and November. Aggregations were present at least from July through December. Massed nesting occurs each year on these same beaches and the event is known as the “salida de flota” by the natives of Guanacaste Province. Numerous less important nesting beaches were also found. Nesting density did not correlate well with beach quality but, instead, appeared to be related to the proximity of the beach to offshore currents. Oceanic current systems apparently facilitate the transport of sea turtles to the general vicinity of the important nesting beaches on both coasts of Coata Rica.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00347753
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    The rate of growth of asterionella formosa Hass. in relation to its ecology (1962)
    Springer
    Archives of microbiology 42 (1962), S. 117-129 
    Details
    ISSN: 1432-072X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In Windermere, and some other lakes in the English Lake District, the vernal increase of Asterionella formosa ceases when the concentration of silica in the water falls to approximately 0.5 mg/l. When this planktonic diatom is cultivated in water from one of these lakes, Windermere, the addition of small amounts of phosphate phosphorus permits the growth of so large a crop that all the silica present is incorporated into the cells. The intensity and duration of the illumination and the temperature of the water effect this relationship between silica, phosphorus and the growth Asterionella. Therefore, the regular, observed relationship between the concentration of silica and the vernal maximum of Asterionella in nature may be related to the amount of this substance in the water, to the amount of phosphate phosphorus present and to the rate of growth imposed upon this diatom by the light and temperature conditions in the lake during the period concerned. The possible importance of the relatively low concentration of phosphate phosphorus in certain very unproductive lakes is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00408168
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Respiratory properties of the blood of the thornback ray (1974)
    Springer
    Cellular and molecular life sciences 30 (1974), S. 167-168 
    Details
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Résumé Quelques propriétés respiratoires du sang de la raie (Raia clavata) ont été déterminées avec des échantillons de cathéter intravasculaire. Chaque échantillon était utilisé seulement pour deux points de la courbe de dissociation −O2−, parce que les propriétés changent après une demie-heure. On a constaté un effet de Bohr (Δ log P50/Δ pH=−0.25±0.03) ainsi que celui d'Haldane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01927712
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Theoretical analysis of the radial field vortex magneto-gas dynamic generator (1962)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 13 (1962), S. 1-13 
    Details
    ISSN: 1420-9039
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Zusammenfassung Der magneto-gas-dynamische Wirbelgenerator mit strahlenförmigem Magnetfeld wird theoretisch untersucht. Geschwindigkeitsprofile, elektrische Kenngrössen und Wirkungsgrade werden unter Berücksichtigung der Induzierten Ströme und Felder besprochen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01600753
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Expulsion of the sex chromosome from the spindle in spermatocytes of a mantid (1950)
    Springer
    Chromosoma 3 (1950), S. 257-270 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. In the primary spermatocytes of the mantid Humbertiella indica the separation of the centers during late prophase is accompanied by corresponding movements of the nuclear membrane. Center and membrane thus remain in close juxtaposition suggesting that some form of attraction operates between them. 2. Interpolar distances are subject to a series of changes definitely associated with the successive mitotic phases. At the initiation of spindle formation the distance between the centers is large; it decreases sharply until metaphase; then remains constant until mid anaphase; and progressively increases to an extreme degree during late anaphase and early telophase. 3. At first metaphase the autosomal bivalents orient in a typical equatorial plate, but the X chromosome lies out in the cytoplasm, spatially separated from the spindle body by a wall of mitochondria. 4. Expulsion of the X chromosome from the spindle is correlated with a delay in its kinetochore-center interaction. 5. The anaphase movement of the autosomes is associated with a progressive shortening of the chromosomal fibers during the entire anaphase, accompanied during late anaphase by an elongation of the spindle body. But in the case of the X chromosome shortening of the chromosomal fiber occurs only during late anaphase. 6. Subsidiary conclusions on the cytoplasmic origin of the chromosomal fiber of the X, the relation of the bouquet stage to the double polarization of late prophase, the non-chiasmate structure of the autosomal bivalents, and the absence of the premetaphase stretch stage are recorded.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00319479
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    The chromosomes of mantids (Orthoptera: manteidae) in relation to taxonomy (1950)
    Springer
    Chromosoma 4 (1950), S. 1-55 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distinguishing cytological characters, including chromosome number and sex chromosome mechanism, have been tabulated for all mantids thus far studied cytologically—including 16 species (starred in Table 1) not hitherto examined. Data on 46 species in 17 subfamilies are reviewed. The XO♂—XX ♀ sex chromosome mechanism represents the ancestral condition for the family and has been retained in 14 of the subfamilies sampled. The distribution of the X1X2Y♂—X1X1X2X2♀ mechanism, previously known in the subfamilies Manteinae and Choeradodinae, is extended to include Mellierinae, Acromantinae and Vatinae. Cytological evidence indicates a monophyletic origin of the compound sex chromosomes and necessitates a reconsideration of the taxonomic association of XO and X1X2Y forms in the same subfamily, specifically of Miomantis and Callimantis with the other Manteinae, and Aethalocroa with Vates and Phyllovates in the Vatinae. The pre-metaphase stretch is established as a regular stage in male meiosis in 14—and is absent in 3—of the species checked for this character. It should prove of taxonomic value when a wider sampling of the lower categories is available. The prolongation of parallel pairing of homologous chromosomes in male meiosis appears to be characteristic of the Manteidae as a whole. No correlation is apparent between the degree of its expression and taxonomic category. Since it provides a mechanism, additional or alternative to chiasmata, for the post-pachytene association of homologues, its establishment permits the evolution of non-chiasmate meiosis in the group. Two structural types of bivalents—one with, one without chiasmata—are found. Present evidence favors the multiple origin of the non-chiasmate type within the family, and since both types may coexist in the karyotype of the same sex of a single species, presence or absence of chiasmata cannot be considered a valid taxonomic criterion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00325766
    Standort Signatur Erwartet Verfügbarkeit
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