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  • 1
    Electronic Resource
    Electronic Resource
    FLAKE FEEDING DEVICE FOR SOLVENT EXTRACTION OF OIL-BEARING MATERIALS (1952)
    s.l. : American Chemical Society
    Industrial & engineering chemistry 44 (1952), S. 2261-2264 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie50513a073
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  • 2
    Electronic Resource
    Electronic Resource
    The role of genes influencing the corolla in pollination of Antirrhinum majus (2000)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 23 (2000), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Studies of pollination ecology have been hindered by an absence of biochemical information about the basis of polymorphism. Using model plants and mutant lines described by molecular genetics may circumvent this difficulty. Mutation of genes controlling petal colour and petal epidermal cell shape in Antirrhinum majus was previously shown to influence fruit set. White flowers set less fruit than magenta flowers and mutants with flat petal epidermal cells set less fruit than flowers with conical cells. Here we analyse the causal pathway underlying this phenomenon through a study of floral characteristics and bee behaviour. Results indicate that bees recognized plants with magenta conical-celled flowers at a distance and did not approach white flowers or magenta flat-celled flowers so frequently. Petal cell shape interacted with colour in determining whether an approaching bee landed on a flower within a plot and whether a bee landing on a flower would probe it. The intrafloral temperature of flowers with conical petal cells was shown to increase with solar irradiance, unlike the intrafloral temperature of flowers with flat petal cells. The difference in fruit set may reflect pollinator discrimination between genotypes as a consequence of the effect of intrafloral temperature on nectar quality and quantity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00580.x
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  • 3
    Electronic Resource
    Electronic Resource
    Kazziha, Walid W.Khader, Bichara; NaïmKerr, Malcolm H.Levy, Avigdor: Revolutionary Transformation in the Arab World: Habash and His Comrades from Nationalism to MarxismTextes de la révolutaion palestinienne, 1968–74The Elusive Peace in the Middle EastThe Arab-Isreali Conflict: Risks and Opportunities : New York, St. Martin's Press, 1975Paris, Sindbad, La Bibliothéque arabe, 1975Albancy, N. Y., State University of New York Press, 1975Tel Aviv, The Israeli Institute for Strategic Studies and Policy Analysis, 1975 (1979)
    New York : Cambridge University Press
    International journal of Middle East studies 10 (1979), S. 282-284 
    Details
    ISSN: 0020-7438
    Source: Cambridge Journals Digital Archives
    Topics: Ethnic Sciences , History , Political Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1017/S0020743800034851
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  • 4
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    THE TRUE MEANING OF PAY-AS-YOU-GO IN FINANCINE OLD AGE RETIREMENT. (1942)
    Chicago : Periodicals Archive Online (PAO)
    Social service Review. 16:1/4 (1942:Mar./Dec.) 75 
    Details
    ISSN: 0037-7961
    Topics: Sociology
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:1205-1942-016-01-000005
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  • 5
    Electronic Resource
    Electronic Resource
    Aneuploidy and isolation in two Hypochoeris species (1975)
    Springer
    Chromosoma 52 (1975), S. 89-101 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The annual species Hypochoeris glabra (2n = 10) and the perennial H. radicata (2n = 8) hybridise readily in nature and in experiment. During meiosis in F1 hybrids the maximum association is a chain of seven and a bivalent indicating that at least three interchanges differentiate the two genomes. The nucleolar chromosomes in the two species are homologous and form a ring bivalent. They are, however, differentiated since in the F1 hybrid only one nucleolar-organiser region is expressed. Although chromosomal differentiation reduces the egg fertility of F1 hybrids to about 1%, viable backcross hybrids to H. radicata as pollen parent have been experimentally produced and occur in natural populations. Backcrosses with 8, 9 and rarely 13 chromosomes are found and those with 2n = 8 are fully interfertile with H. radicata. Gene flow may therefore take place in natural populations across an aneuploid barrier. The direction of gene flow in Hypochoeris is probably unidirectional from the annual to the perennial.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285792
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  • 6
    Electronic Resource
    Electronic Resource
    Nucleolar-organiser polymorphism in natural populations of Allium schoenopmsum (1976)
    Springer
    Chromosoma 56 (1976), S. 301-307 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Allium schoenoprasum, 2n=16, has a single pair of highly acrocentric chromosomes which always have nucleolar-organiser regions on the short arms. In some British populations one or both homologues of submetacentric chromosome 7 may also carry a nucleolar-organiser region terminal on the long arm. These supernumerary satellites are simply inherited. Of the 13 populations examined, six were polymorphic for chromosome 7s. The frequency of chromosome 7s ranges from 0.130 to 0.825 and the distribution of the three karyotypes in all these populations corresponds to a HardyWeinberg equilibrium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293193
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  • 7
    Electronic Resource
    Electronic Resource
    The B-chromosome system of Hypochoeris maculata (1978)
    Springer
    Chromosoma 67 (1978), S. 123-143 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The meiotic process in PMCs of Hypochoeris maculata is progressively disrupted in the presence of two or more B-chromosomes. Bivalent formation and chiasma conditions are unaffected by up to 3Bs although some univalence occurs with higher numbers. Spindle behaviour, however, is inefficient at both first and second division in the presence of two or more Bs. At metaphase I, regular equatorial alignment breaks down and A-bivalents sometimes show amphitelic or monosyntelic orientation. Anaphase I is characterised by irregular segregation, equatorial laggards and centric division products. The proportion of normal anaphase segregations declines by 20% for every B more than one. A-chromosome laggards, but not Bs, can induce nuclear restitution at telophase I. Following centric division at anaphase II poleward movement can fail leading to further nuclear restitution. Telophase II nuclei thus can be approximately haploid, diploid or tetraploid with aneuploid variation around the haploid and diploid levels. The frequency of numerical mutants in the offspring indicates that EMC meiosis is much less susceptible to the presence of Bs than PMC meiosis: only 4- and 5Bt plants have an enhanced frequency of numerically-aberrant offspring. The deleterious effects of Bs on meiotic efficiency will contribute to setting an upper limit on B-numbers in natural populations of this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293170
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  • 8
    Electronic Resource
    Electronic Resource
    The B-chromosome system of Allium schoenoprasum (1975)
    Springer
    Chromosoma 53 (1975), S. 273-282 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Populations of Allium schoenoprasum, 2n=16, from six of the eight British localities have been examined. A B-chromosome polymorphism has been found which is limited to the River Wye, South Wales, where A. schoenoprasum grows along a 15 kilometre stretch. Four interrelated types of small, euchromatic, mitotically-stable B-chromosomes occur. Twelve different B-karyotypes, including an individual with 18 Bs, have been recorded. Populations contain up to 39% of plants with Bs. The B-chromosomes are not uniformly distributed along the river but are limited to populations in the downstream part of the range. An abrupt change from 34% to 0% B-contaiuing plants takes place over only 1.2 kilometres. The unique combination of riverside populations in linear order and the sudden discontinuity in the cytological structure of these populations may enable the factors influencing B-chromosome distribution to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329177
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  • 9
    Electronic Resource
    Electronic Resource
    The B-chromosome system of Hypochoeris maculata (1976)
    Springer
    Chromosoma 59 (1976), S. 167-177 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Populations of Hypochoeris maculata (Compositae) over a wide area of Europe contain a small proportion of individuals with mitoticallystable B-chromosomes. The telocentric Bs are about one sixth the length of the smallest A-chromosome and are heterochromatic. Offspring grown from seeds of natural populations have one or at most two B-chromosomes although plants with up to five Bs have been produced in experiment. The Bs rarely pair during meiotic prophase and the univalents usually undergo centric division at anaphase I. Despite lagging, the Bs are rarely lost during male meiosis. The inheritance of the B-chromosomes differs between the two sides with accumulation in the egg and random inheritance or loss on the pollen side. Although meiotic drive may play some part in the maintenance of the B-polymorphism there is a strict upper limit on the number of Bs in natural populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328485
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  • 10
    Electronic Resource
    Electronic Resource
    Chiasma frequency effects of structural chromosome change (1982)
    Springer
    Chromosoma 85 (1982), S. 673-686 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Three structural chromosome changes in the plant Hypochoeris radicata 2n = 8 have been tested for their effects on chiasma formation: (1) centric fission of chromosome 1, (2) a whole arm exchange between chromosomes 1 and 3, and (3) an interchange between the long arm of chromosome 1 and the short arm of 2 which gives an effectively three-armed pachytene multiple. Mean chiasma frequencies were compared between full-sibs in families segregating for the rearrangements. In each family the chiasma frequency was higher in heterozygotes than basic homozygotes. The size of the chiasma increase is dependant on the number of additional potentially-paired segments in the complement at pachytene. Fission heterozygotes and 1/2 interchange heterozygotes, with one extra pairing region, both form about 0.45 more chiasmata per PMC than full-sib basic homozygotes. The 1/3 exchange, with two additional pairing regions, increases chiasma frequency by twice this, about 0.85 per PMC. Individuals homozygous for the centric fission maintain the raised chiasma level. The chiasma increase appears limited to the chromosome(s) affected by structural change with no detectable interchromosomal effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330780
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