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  • American Physical Society  (68)
  • Springer  (34)
  • 1960-1964  (52)
  • 1950-1954  (46)
  • 1920-1924
  • 1
    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
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  • 2
    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
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  • 3
    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
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  • 4
    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
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  • 5
    Digitale Medien
    Digitale Medien
    The kinetochore of the hemiptera (1961)
    Springer
    Chromosoma 12 (1961), S. 327-350 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary (1) Breakage of chromosomes was induced by X-rays in adult and nymphal males of Euschistus servus, E. tristigmus and Solubea pugnax (Pentatomidae; Hemiptera-Heteroptera). (2) The diffuse nature of the kinetochore is demonstrated by the ability of chromosome fragments to perpetuate themselves mitotically through many cell generations of spermatogonia. (3) Free fragments, when not immobilized by the effects of radiation, are also capable of meiotic mitosis. A holokinetic, rather than a telomeric, nature is thus demonstrated for the meiotic restriction of kinetochore activity to chromosome ends, normal for Heteroptera and certain other Hemiptera. (4) Simple fragmentation as a factor in the evolution of compound sex chromosomes is supported by the observation that fragments of the X chromosome co-orient with the Y in a typical “touch and go” pairing. (5) The results are discussed with relation to problems of kinetochore structure and mitosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00328928
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  • 6
    Digitale Medien
    Digitale Medien
    The nuclear content of desoxyribonucleic acid and interspecific relationships in the mantid genus Liturgousa (Orthoptera: Mantoidea) (1953)
    Springer
    Chromosoma 5 (1953), S. 544-554 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. The mantidLiturgousa sp. n. of Trinidad, B. W. I., although in external morphology practically indistinguishable fromL. maya, is cytologically distinct from all other species thus far studied.L. sp. n. has 21 chromosomes (2n ♂),L. maya 17,L. actuosa 23 andL. cursor 33. 2. Although the total length of all the chromosomes of the complement is approximately the same in all four species, the DNA content of the spermatid nucleus, microspectrophotometrically determined, differs to a striking degree. Nuclei ofL. sp. n. andL. actuosa carry one and one half times as much DNA as do those ofL. maya andL. cursor. 3. The significance of these findings is discussed with reference to evolutionary relationships within the genus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01271501
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  • 7
    Digitale Medien
    Digitale Medien
    The “pre-metaphase stretch” and kinetochore orientation in phasmids (1950)
    Springer
    Chromosoma 3 (1950), S. 1-21 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. The pre-metaphase stretch is found to be a normal stage in male meiosis in six species of phasmids. 2. Its essential features are a precocious orientation of the kinetochores and their movement toward opposite poles of the developing spindle in first meiotic prophase, — with a consequent stretching of the chromosomes. It is followed by recontraction of the chromosomes and their movement to the equator. Attraction beween kinetochore and center, reinforced by the effect of elongation of the spindle, is considered responsible for the movements of the stretch. 3. The pre-metaphase stretch in phasmids differs from that of mantids in (1) its timing relative to meiotic stage, and (2) its expression in one species in the prophase of both meiotic divisions. 4. The distribution of the stretch in nature, and its significance for the mechanism of mitosis are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00319466
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  • 8
    Digitale Medien
    Digitale Medien
    Reversion of XO to XY sex chromosome mechanism in a phasmid (1950)
    Springer
    Chromosoma 3 (1950), S. 52-65 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The sex chromosomes of the male phasmid Isagoras schraderi Rehn comprise an X and a Y, — each with a submedian kinetochore, and one euchromatic and one heterochromatic arm. At meiosis X and Y form an unequal sex bivalent in which the euchromatic arms are terminally associated. Relatively recent reversion from the XO-XX mechanism characteristic of the Phasmidae is indicated by the presence of the euchromatic arm in both X and Y. The diploid number of the male is 34. Unequal autosomal bivalents are found at meiosis in two other species of Isagoras — Isagoras subaquiles Rehn and Isagoras sp. — and in Pseudophasma menius Westwood. The chromosome complements of these species are described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00319469
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  • 9
    Digitale Medien
    Digitale Medien
    Supplementary notes on the cyto-taxonomy of mantids (Orthoptera: Mantoidea) (1953)
    Springer
    Chromosoma 6 (1953), S. 79-90 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 1. Chromosome number, sex chromosome mechanism and the salient features of male meiosis have been determined for the following neotropical mantids:Promiopteryx granadensis (Sauss.),Thesprotia filum (Licht.),Thesprotia graminis (Scudder),Tithrone roseipennis (Sauss.),Acanthops falcata Stol,Oxyopsis rubicunda (Stol); and the female diploid number forAcontiothespis multicolor (Sauss.). This adds one more subfamily of mantids, theMiopteriginae, to the list for which cytological information is now available, and gives the first data on meiosis for two others—the Oligonicinae and theEpaphroditinae. 2. The subfamilyMiopteriginae, as exemplified byPromiopteryx, is characterized by the XO-XX sex mechanism and in male meiosis by prolongation of parallel pairing, non-chiasmate bivalent structure and absence of the pre-metaphase stretch stage; close correspondence with thePseudomiopteriginae is evident. Relatively low number and small size of chromosomes give a total chromosomal content approximately half that found in X1X2Y manteine karyotypes. The possibility of a polyploid relation is discussed. 3. Oxyopsis, presently assigned to theVatinae, is shown to belong to the natural group of genera characterized by possession of the compound X1X2Y sex chromosome mechanism; cytologically it is most closely associated withStagmatoptera of theManteinae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01259932
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  • 10
    Digitale Medien
    Digitale Medien
    The synthesis of corticosteroids methylated at C21 (1960)
    Springer
    Cellular and molecular life sciences 16 (1960), S. 357-358 
    Details
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Zusammenfassung Die Darstellung der beiden epimeren C21-Methylderivate des 9α-Fluorprednisolons wird beschrieben. 9α-Fluor-21-methyl-1, 4-pregnadien-11β, 17α, 21B-triol-3, 20-dion-21-azetat ist ein hochwirksames entzündungshemmendes Steroid, vollkommen frei von Nebenwirkungen der Natrium- und Wasserretention des C21-unsubstituierten 9α-Fluorprednisolons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02157901
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