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  • 1
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Free Radical Biology and Medicine 10 (1991), S. 177-184 
    ISSN: 0891-5849
    Schlagwort(e): Free radicals ; Humans ; Noninvasive analytical techniques ; Oxidative stress status
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Mutation Research DNAging 256 (1991), S. 45-48 
    ISSN: 0921-8734
    Schlagwort(e): Ageing ; Humans ; Skin cells ; Telomeres
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 304 (1994), S. 285-294 
    ISSN: 0027-5107
    Schlagwort(e): Cotinine ; Genetic monitoring ; Hprt mutation ; Humans ; Lymphocytes ; Pregnancy ; Smoking ; Tobacco
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Mutation Research DNAging 237 (1990), S. 123-130 
    ISSN: 0921-8734
    Schlagwort(e): Aging ; Humans ; Ionizing radiation ; Single cell electrophoresis
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Peptides 10 (1989), S. 489-492 
    ISSN: 0196-9781
    Schlagwort(e): Angiotensin II ; Blood ; Humans ; Radioimmunoassay ; Rats ; [des-Leu^1^0]-angiotensin I
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Peptides 13 (1992), S. 287-290 
    ISSN: 0196-9781
    Schlagwort(e): Autocrine feedback mechanism ; Cholecystokinin ; Feeding ; Humans ; Radioimmunoassay
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Applied Animal Behaviour Science 39 (1994), S. 141-150 
    ISSN: 0168-1591
    Schlagwort(e): Cats ; Foraging ; Humans ; Livestock ; Predators ; Vampire bats
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Applied Animal Behaviour Science 41 (1994), S. 101-114 
    ISSN: 0168-1591
    Schlagwort(e): Fear ; Handling ; Humans ; Poultry ; Productivity
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Thermal Biology 5 (1980), S. 249-251 
    ISSN: 0306-4565
    Schlagwort(e): Humans ; exercise ; hyperthermia ; oesophageal temperature
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 39-52 
    ISSN: 0308-597X
    Schlagwort(e): Ecology ; Fisheries ; Marine resources
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 43-57 
    ISSN: 0308-597X
    Schlagwort(e): Atlantic ; Fisheries ; Management
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 126-133 
    ISSN: 0308-597X
    Schlagwort(e): Fisheries ; Government ; USA
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 61-62 
    ISSN: 0308-597X
    Schlagwort(e): Fisheries ; Marketing ; UK
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 8 (1984), S. 137-150 
    ISSN: 0308-597X
    Schlagwort(e): Fisheries ; International organizations ; Management
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 7 (1983), S. 197-211 
    ISSN: 0308-597X
    Schlagwort(e): Fisheries ; Management ; Property rights
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 219-235 
    ISSN: 0308-597X
    Schlagwort(e): Canada ; Fisheries ; Foreign relations
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 66-68 
    ISSN: 0308-597X
    Schlagwort(e): Fisheries ; Regional government organizations ; West Africa
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 120-125 
    ISSN: 0308-597X
    Schlagwort(e): Exclusive Economic Zones ; Fisheries ; Law of the Sea
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 27-42 
    ISSN: 0308-597X
    Schlagwort(e): Fisheries ; International law ; United Nations Organization
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 131-139 
    ISSN: 0308-597X
    Schlagwort(e): Economic measurements ; Fisheries ; Pacific
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 7 (1983), S. 267-278 
    ISSN: 0308-597X
    Schlagwort(e): Environment ; Fisheries ; Resource management
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 6 (1982), S. 121-130 
    ISSN: 0308-597X
    Schlagwort(e): Atlantic ; Fisheries ; Management
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 8 (1984), S. 239-258 
    ISSN: 0308-597X
    Schlagwort(e): Antarctica ; Fisheries ; Krill
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Marine Policy 9 (1985), S. 220-236 
    ISSN: 0308-597X
    Schlagwort(e): Fisheries ; Resource economics, UK
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Politikwissenschaft , Rechtswissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Agriculture and human values 17 (2000), S. 125-139 
    ISSN: 1572-8366
    Schlagwort(e): Environment ; Fisheries ; Fordism ; Nation-State ; Regulation ; Supranational State ; Transnational corporations ; Transnational State
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract This analysis uses an analytical frameworkgrounded in political economy perspectives of theglobalization of the agro-food sector combined with acase study approach focusing on the Marine StewardshipCouncil (MSC) to inform discussions regarding thecharacteristics of societal regulation in thepost-Fordist era. More specifically, this analysisuses the case of the emergence of the MSC toinvestigate propositions regarding the existence of,and location of, nascent forms of a transnationalState. The MSC proposes to regulate the certificationof sustainable fisheries at the global level throughan eco-labeling program. The MSC was created in 1996by the transnational environmental organization theWorld Wildlife Fund and the transnational corporationUnilever. The emergence of the MSC has generatedheated discussion in fisheries management circles thatis in general divided along North/South lines. Thisanalysis indicates that the case of the MSC providesvaluable insights into the possible characteristics ofsupranational regulatory mechanisms that might emulatethe role of the nation-State in the post-Fordist era.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 27 (1988), S. 311-320 
    ISSN: 1432-1432
    Schlagwort(e): Genome composition ; Coding sequences ; Isochores ; Humans ; Murids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The compositional distributions of coding sequences and DNA molecules (in the 50-100-kb range) are remarkably narrower in murids (rat and mouse) compared to humans (as well as to all other mammals explored so far). In murids, both distributions begin at higher and end at lower GC values. A comparison of homologous coding sequences from murids and humans revealed that their different compositional distributions are due to differences in GC levels in all three codon positions, particularly of genes located at both ends of the distribution. In turn, these differences are responsible for differences in both codon usage and amino acids. When GC levels at first+second codon positions and third codon positions, respectively, of murid genes are plotted against corresponding GC levels of homologous human genes, linear relationships (with very high correlation coefficients and slopes of about 0.78 and 0.60, respectively) are found. This indicates a conservation of the order of GC levels in homologous genes from humans and murids. (The same comparison for mouse and rat genes indicates a conservation of GC levels of homologous genes.) A similar linear relationship was observed when plotting GC levels of corresponding DNA fractions (as obtained by density gradient centrifugation in the presence of a sequence-specific ligand) from mouse and human. These findings indicate that orderly compositional changes affecting not only coding sequences but also noncoding sequences took place since the divergence of murids. Such directional fixations of mutations point to the existence of selective pressures affecting the genome as a whole.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 35 (1992), S. 7-16 
    ISSN: 1432-1432
    Schlagwort(e): Alu source genes ; Humans ; Gorillas ; Retrotransposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A member of the young PV Alu sub-family is detected in chimpanzee DNA showing that the PV subfamily is not specific to human DNA. This particular Alu is absent from the orthologous loci in both human and gorilla DNAs, indicating that PV subfamily members transposed within the chimpanzee lineage following the divergence of chimpanzee from both gorilla and human. These findings and previous reports describing the transpositional activity of other Alu sequences within the human, gorilla, and chimpanzee lineages provide phylogenetic evidence for the existence of multiple Alu source genes. Sequences surrounding this particular Alu resemble known transcriptional control elements associated with RNA polymerase III, suggesting a mechanism by which cis-acting elements might be acquired upon retrotransposition.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 33 (1991), S. 442-449 
    ISSN: 1432-1432
    Schlagwort(e): Humans ; Mouse ; Rat ; Codon usage ; Mutation bias ; Selection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A new statistical test has been developed to detect selection on silent sites. This test compares the codon usage within a gene and thus does not require knowledge of which genes are under the greatest selection, that there exist common trends in codon usage across genes, or that genes have the same mutation pattern. It also controls for mutational biases that might be introduced by the adjacent bases. The test was applied to 62 mammalian sequences, the significant codon usage biases were detected in all three species examined (humans, rats, and mice). However, these biases appear not to be the consequence of selection, but of the first base pair in the codon influencing the mutation pattern at the third position.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 34 (1992), S. 336-344 
    ISSN: 1432-1432
    Schlagwort(e): Humans ; Mitochondrial DNA ; Nuclear polymorphisms ; Heteroplasmy ; Genetic differentiation ; Sickle cell ; Rain forest refuges
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The identification of genetically coherent populations is essential for understanding human evolution. Among the culturally uniform ethnic groups of west Africa, there are two geographically distinct populations with high frequencies of sickle-cell hemoglobin (HbS). Although the HbS mutation in each group is found on distinguishable chromosomes 11, these populations have been assumed to be parts of a single population. Analysis of mitochondrial DNA (mtDNA) in these populations demonstrated that the two populations identified by alternative chromosomes 11 bearing HbS have distinct distributions of mitochondrial genotypes, i.e., they are maternally separate. These studies also showed that, contrary to expectation, the mtDNA of some individuals is heteroplasmic. For nuclear loci, a comparison of the frequency of alternative alleles established that these populations are genetically distinct. Both the mitochondrial and nuclear data indicate that these populations have been separate for approximately 50,000 years. Although HbS in the two populations is usually attributed to recent, independent mutations, the duration of the separation and the observed geographic distribution of the population allow for the possibility of an ancient origin of HbS. Assuming an ancient mutation and considering the known biogeography, we suggest that HbS protected selected populations from malaria in rain forest refuges during the most recent ice age.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Peptides 4 (1983), S. 451-455 
    ISSN: 0196-9781
    Schlagwort(e): Biliary system ; Cat ; Guinea-pig ; Humans ; Mucosa ; Rabbit ; Radioimmunoassay ; Respiratory system ; Skin ; Substance P ; Sympathetic nervous system ; Urinary system
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Peptides 1 (1980), S. 55-57 
    ISSN: 0196-9781
    Schlagwort(e): ACTH ; Aging ; Attention ; Cognition ; Humans ; MSH ; Peptide ; Visual retention
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Peptides 5 (1984), S. 319-323 
    ISSN: 0196-9781
    Schlagwort(e): Blood flow ; Circulation ; Electromagnetic flowmetry ; Humans ; VIP
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    ISSN: 0165-7992
    Schlagwort(e): Cytochrome P-450 ; Dogs ; Humans ; Monkeys ; P-448-H ; Rats
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Ethology and Sociobiology 6 (1985), S. 183-187 
    ISSN: 0162-3095
    Schlagwort(e): Assortative mating ; Genetic similarity ; Heritability ; Humans ; Kin recognition
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Ethology and Sociobiology 8 (1987), S. 215-220 
    ISSN: 0162-3095
    Schlagwort(e): Humans ; Paternity confidence ; Relatedness
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Mycopathologia 124 (1993), S. 73-77 
    ISSN: 1573-0832
    Schlagwort(e): Assessment ; Cancer ; Humans ; Hydrazines ; Mushroom
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract This assessment focuses on the concentrations of some chemicals present in theAgaricus bisporus mushroom, the cancer-inducing doses of these chemicals or mushroom used in the animal experiments, the total amounts of these chemicals or mushroom needed to induce cancer in these mice, and the estimated total amounts of these chemicals or mushroom needed to induce cancer in humans. By adding the estimated amounts of chemicals needed to induce cancer and by comparing it with the amount of raw mushroom needed to induce the same effect, it becomes obvious that we have accounted for less than 2% of the carcinogenic components of theAgaricus bisporus mushroom. Since some unavailable data handicapped this assessment, it should be regarded as tentative and subject to further adjustment.
    Materialart: Digitale Medien
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    International journal of biometeorology 34 (1990), S. 42-48 
    ISSN: 1432-1254
    Schlagwort(e): Briths ; Humans ; Solar wind ; Geomagnetism ; Melatonin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geographie , Physik
    Notizen: Abstract Data obtained from the literature on the annual pattern of human conceptions and plasma melatonin at high latitudes indicated that simple annual rhythms do not exist. Instead, prominent semiannual rhythms are found, with equinoctial troughs and solsticial peaks. A prominent semiannual environmental event is the magnetic disturbance induced by the solar wind. The semiannual magnetic disturbances are worldwide, but most pronounced in the auroral zones where the corpuscular radiation enters the atmosphere. Magnetic indices that predominantly reflect these events were obtained from the literature and correlated with the melatonin and conception data. Significant and inverse correlations were found for Inuit conceptions and the melatonin data. The correlations obtained for 48 contiguous states of the United States indicated that only the extreme northern states exhibited this relationship. These data were compared with a previous correlational study in the United States which established that sunshine was correlated with conceptions in the middle latitude and southern states. An hypothesis of dual control by electromagnetic and magnetic energies is proposed: melatonin is a progonadal hormone in humans controlled by both factors, depending on their relative strength. Other studies are reviewed regarding the possible factors involved in determining the annual pattern of human conceptions. Demographic studies of geographic variation in temporal patterns of conceptions, with particular regard to variations of the magnetic fields on the earth's surface, may provide some insight into the efficacy of these different factors.
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  • 38
    ISSN: 1432-1009
    Schlagwort(e): Reservoir ; Fisheries ; Breeding and wintering waterbirds ; Raising water levels ; Habitat change
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract A new, higher dam was installed at Kerkini Reservoir in 1982, causing habitat and landscape disruption. A decrease in the area of grassland and shallow water areas, the rapid disappearance of reedbeds, the appearance of beds ofNymphaea, and the disappearance of half the forest area were all observed between 1982 and 1991. With the new hydrological regime, a lacustrine system was created, with an extensive, rather deep (4–8 m), pelagic zone favorable for the development of coarse fish species throughout the year. After 1982, an increase in fishing effort and a change in the relative abundance of fish species in the catch, including the disappearance of eels and wels, were observed. The impact of the rise in the water level of breeding aquatic birds led to a general decline in species typical of marshy habitats in favor of species preferring deeper open water habitats. A decrease was recorded in bird species that feed largely on invertebrates and to a lesser extent fish (e.g., glossy ibis) and that require extensive shallow feeding areas. There was a decline in geese, whose nests were regularly flooded, and a major increase in piscivorous birds, particularly diving birds (e.g., cormorants), which prefer deeper open water and benefitted directly from the large increase in coarse fish biomass. The disappearance of birds breeding in flooded meadows (e.g., black-winged stilts) and of those restricted to reedbeds (e.g., marsh harrier) occurred from 1983. Over the same period, the changes in populations of wintering birds at Kerkini were different from those occurring in other wetlands in northern Greece. The changes recorded in the populations of wintering birds at Kerkini did not therefore result from overall regional trends but from the major habitat modifications that occurred to this wetland. As for breeding birds, strictly piscivorous species increased greatly as a result of the increased availability of fish, but also due to the appearance of many suitable night roosting sites (flooded trees) and to the great increase in the area of open water greater than 2 m deep. Today, Kerkini has become the most important breeding site in Greece for a majority of colonial waterbirds. In contrast, wintering shorebirds practically disappeared. The many changes recorded in the status of breeding and wintering birds at Kerkini can mostly be explained by the changes that occurred in the functioning of the ecosystem and in the habitat structure following the inauguration of the new hydrological regime. These changes did not all occur at the same time: some were immediate and others required a delay before they could be detected.
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  • 39
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    Environmental management 16 (1992), S. 225-229 
    ISSN: 1432-1009
    Schlagwort(e): Fisheries ; Phosphorus ; Contaminants ; Ecosystem ; Management ; Simulation model ; Great Lakes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract A simulation model was developed to describe linkages among fish food web, nutrient cycling, and contaminant processes in the southern basin of Lake Michigan. The model was used to examine possible effects of management actions and an exotic zooplankter (Bythotrephes) on Lake Michigan food web and contaminant dynamics. The model predicts that contaminant concentrations in salmonines will decrease by nearly 20% ifBythotrephes successfully establishes itself in the lake. The model suggests that this decrease will result from lowered transfer efficiencies within the food web and increased flux of contaminants to the hypolimnion. The model also indicates that phosphorus management will have little effect on contaminant concentrations in salmonines. The modeling exercise helped identify weaknesses in the data base (e.g., incomplete information on contaminant loadings and on the biomass, production, and ecological efficiencies of dominant organisms) that should be corrected in order to make reliable management decisions.
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  • 40
    Digitale Medien
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    Environmental management 7 (1983), S. 151-160 
    ISSN: 1432-1009
    Schlagwort(e): Grass carp ; Biological control ; Nuisance aquatic weeds ; Fisheries ; Aquaculture ; Reproductive requirements ; Arkansas management plan ; Sterile hybrids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Grass carp (Ctenopharyngodon idella Val.) were introduced into the United States in 1963 as potential biological control agents for nuisance aquatic weeds. Since that time an oftentimes bitter controversy has raged over its effects on sportfishing, and its possible natural reproduction and naturalization in North America. This review considers the history, ecology, and present status of grass carp in the United States in light of the voluminous scientific research conducted since its importation. Particular attention is given to the role of grass carp in the fisheries management plans of Arkansas. Recent development of a sterile, triploid grass carp hybrid may lead to widespread use of grass carp to control nuisance aquatic weeds in culturally eutrophicated waters of the United States.
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  • 41
    Digitale Medien
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    Environmental management 11 (1987), S. 479-493 
    ISSN: 1432-1009
    Schlagwort(e): Flushing ; Scouring ; Channel Maintenance ; Fisheries ; Trinity River
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract The operation of Trinity and Lewiston Dams on the Trinity River in northern California in the United States, combined with severe watershed erosion, has jeopardized the existence of prime salmonid fisheries. Extreme streamflow depletion and stream sedimentation below Lewiston have resulted in heavy accumulation of coarse sediment on riffle gravel and filling of streambed pools, causing the destruction of spawning, nursery, and overwintering habitat for prized chinook salmon (Salmo gairdnerii) and steelhead trout (Oncorhynchus tschawytscha). Proposals to restore and maintain the degraded habitat include controlled one-time remedial peak flows or annual maintenance peak flows designed to flush the spawning gravel and scour the banks, deltas, and pools. The criteria for effective channel restoration or maintenance by streambed flushing and scouring are examined here, as well as the mechanics involved. The liabilities of releasing mammoth scouring-flushing flows approximating the magnitude that preceded reservoir construction make this option unviable. The resulting damage to fish habitat established under the postproject streamflow regime, as well as damage to human settlements in the floodplain, would be unacceptable, as would the opportunity costs to hydroelectric and irrigation water users. The technical feasibility of annual maintenance flushing flows depends upon associated mechanical and structural measures, particularly instream maintenance dredging of deep pools and construction of a sediment control dam on a tributary where watershed erosion is extreme. The cost effectiveness of a sediment dam with a limited useful economic life, combined with perpetual maintenance dredging, is questionable.
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  • 42
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    Environmental management 20 (1996), S. 523-539 
    ISSN: 1432-1009
    Schlagwort(e): Water control ; Floodplain ; Fisheries ; Bangladesh ; Chandpur
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Bangladesh is a very flat delta built up by the Ganges—Brahmaputra—Meghna/Barak river systems. Because of its geographical location, floods cause huge destruction of lives and properties almost every year. Water control programs have been undertaken to enhance development through mitigating the threat of disasters. This structural approach to flood hazard has severely affected floodplain fisheries that supply the major share of protein to rural Bangladesh, as exemplified by the Chandpur Irrigation Project. Although the regulated environment of the Chandpur project has become favorable for closed-water cultured fish farming, the natural open-water fishery loss has been substantial. Results from research show that fish yields were better under preproject conditions. Under project conditions per capita fish consumption has dropped significantly, and the price of fish has risen beyond the means of the poor people, so that fish protein in the diet of poor people is gradually declining. Bangladesh is planning to expand water control facilities to the remaining flood-prone areas in the next 15–20 years. This will cause further loss of floodplain fisheries. If prices for closed-water fish remain beyond the buying power of the poor, alternative sources of cheap protein will be required.
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  • 43
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    Environmental management 3 (1979), S. 133-144 
    ISSN: 1432-1009
    Schlagwort(e): Coastal zone Management ; Fisheries ; Marshes ; Wetlands ; Louisiana
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract This paper examines causes and consequences of wetland losses in coastal Louisiana. Land loss is a cumulative impact, the result of many impacts both natural and artificial. Natural losses are caused by subsidence, decay of abandoned river deltas, waves, and storms. Artificial losses result from flood-control practices, impoundments, and dredging and subsequent erosion of artificial channels. Wetland loss also results from spoil disposal upon wetlands and land reclamation projects. Total land loss in Louisiana's coastal zone is at least 4,300 ha/year. Some wetlands are converted to spoil banks and other eco-systems so that wetland losses are probably two to three times higher. Annual wetland losses in the Barataria Bay basin are 2.6% of the wetland area. Human activities are the principal determinants of land loss. The present total wetland area directly lost because of canals may be close to 10% if spoil area is included. The interrelationship between hydrology, land, vegetation, substrate, subsidence, and sediment supply are complicated; however, hydrologic units with high canal density are generally associated with higher rates of land loss and the rate may be accelerating. Some cumulative impacts of land loss are increased saltwater intrusion, loss of capacity to buffer the impact of storms, and large additions of nutrients. One measure of the impact is that roughly $8–17 × 106 (U.S.A.) of fisheries products and services are lost annually in Louisiana. Viewed at the level of the hydrologic unit, land loss transcends differences in local vegetation, substrate, geology, and hydrology. Land management should therefore focus at that level of organization. Proper guideline recommendations require an appreciation of the long-term interrelations of the wetland estuarine system.
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  • 44
    ISSN: 1432-0878
    Schlagwort(e): Skeletal muscles ; Ultrastructure ; Exercise ; Glycogen ; Humans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Distribution of glycogen particles in semithin and ultrathin sections of biopsy samples from human muscles subjected to either short- or long-term running were investigated using PAS and Periodic Acid-ThioSemiCarbazide-Silver Proteinate (PA-TSC-SP) staining methods. Glycogen particles were predominantly found immediately under the sarcolemma or aligned along the myofibrillar Iband. After long-term exhaustive exercise type-1 fibers with a few or no glycogen particles in the core of the fibers were frequently observed. The subsarcolemmal glycogen stores of these “depleted” type-1 fibers were about three times as large as after exhaustive short-time exercise. Another indication of utilization of subsarcolemmal glycogen stores during anaerobic exercise was that many particles displayed a pale, rudimentary shape. This observation suggests fragmental metabolization of glycogen. Thus, depending on type of exercise and type of fiber differential and sequential glycogen utilization patterns can be observed.
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  • 45
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    Journal of science education and technology 2 (1993), S. 397-406 
    ISSN: 1573-1839
    Schlagwort(e): Engineering ; technological literacy ; hands-on experiments ; active learning ; content instruction ; videotaping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Allgemeine Naturwissenschaft , Technik allgemein
    Notizen: Abstract Media reports indicate the decline of the technological literacy of American youth, especially that students in other countries are better prepared in science and mathematics. Our active-learning program, which consists of numerous hands-on experiments, introduces engineering applications into science and math programs, that will demonstrate to students the usefulness of the theory that they currently do not see as useful. The program, when fully developed, will make optimum use of technology, especially computers and videotapes. The hands-on experiments allow students to discover fundamental principles through data analysis and then use the principles to synthesize a solution to a technological problem. This discovery-based education will help school systems better meet performance standards such as those in the Maryland School Performance Plan. The experimental approach to science education is especially important in a technology-oriented economy where children use the new technologies without understanding the principles on which they are based.
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  • 46
    ISSN: 1573-5133
    Schlagwort(e): Chondrichthyes ; Elasmobranchs ; Fisheries ; Ageing methods ; Growth rates ; Gestation periods ; Maturity ; Vertebral bands ; Weight-length relationships ; Life histories
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis The silky shark, Carcharhinus falciformis, and scalloped hammerhead, Sphyrna lewini, represent 〉80% of the shark by-catch of the winter swordfish/tuna longline fishery of the northwestern Gulf of Mexico. This catch represents a potential supplemental fishery, yet little is known of the life histories of the two species. This report relates reproductive biology data to age and growth estimates for 135 C. falciformis and 78 S. lewini. Unlike other regional populations, C. falciformis in the Gulf of Mexico may have a seasonal 12 month gestation period. Males mature at 210–220 cm TL (6–7 yr); females at 〉225 cm TL (7–9 yr). Application of age at length data for combined sexes produced von Bertalanffy growth model parameter estimates of L∞ = 291 cm TL, K = 0.153, t0 = −2.2 yr. Adult male S. lewini outnumbered adult females in catches because of differences in the distributions of the sexually segregated population. Males mature at 180 cm TL (10 yr); females at 250 cm TL (15 yr). von Bertalanffy parameter estimates for combined sexes of this species were L∞ = 329 cm TL, K = 0.073, to = −2.2 yr.
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  • 47
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    Environmental biology of fishes 2 (1977), S. 241-259 
    ISSN: 1573-5133
    Schlagwort(e): Production ; Fisheries ; Population dynamics ; Energetics ; Fishes ; Competition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Production rates of seven species of fishes were determined for one year in a 0.95 ha pond. Total annual production of all fishes in the pond was 209 g m−2y−1 (after the subtraction of 16.2 g m−2y−1 of negative production). Over 90% of the production occurred in the months of June through September, with young-of-the-year fishes contributing 84% of the total. When Y of Y fishes shifted to benthic diets in the spring, the small biomass of benthos available could not sustain the large biomas of fish. Severe competition for the available food then resulted in decreased production rates for the entire fish taxocene.
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  • 48
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    Environmental biology of fishes 7 (1982), S. 177-180 
    ISSN: 1573-5133
    Schlagwort(e): Temperature ; Behavior ; Ecology ; Fisheries ; Fish ; Marine juveniles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Sixteen yearling winter flounder, tested individually for 3-day periods in electronic shuttleboxes, voluntarily occupied an 8–27°C range of temperature, with a modal final thermal preferendum of 18.5°C (mean 18.7°C, median 19°C, midpoint 17.5°C, s.d. 1.9°C, S k + 0.33). The locomotor activity pattern of the yearling fish in the laboratory was markedly nocturnal, with mean hourly nocturnal activity exceeding mean hourly diurnal activity by a factor of 3.4. Maximum activity occurred at 0300 EST, minimum activity at 1400 EST. While activity generally increased with temperature, a local activity minimum occurred at 18.7°C, coinciding with the 24-hour mean final thermal preferendum. Comparison of these laboratory data with previously published field data suggest that behavioral responses to temperature and light play significant roles in determining age- and size-specific differences in seasonal depth stratification and onshore-offshore distributions in this species.
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  • 49
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    Environmental biology of fishes 30 (1991), S. 253-271 
    ISSN: 1573-5133
    Schlagwort(e): Rockfish ; Longevity ; Reproductive value ; Fisheries ; Scorpaenidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis The characteristics of lightly and heavily exploited Pacific ocean perch,Sebastes alutus, stocks are evaluated relative to the predictions of life history theory. These long-lived species (50–100 year lifespan) show limited phenotypic plasticity and have little buffering against the effects of reduced lifespan. Reduced stock abundance has generated some compensatory increase in growth rate. Length at first maturity varies only slightly with increased growth rate, although age at maturity may decrease by 1–4 years. Grooth increases yield larger (15–20%) size at age and increased reproductive effort at younger ages, but lower size-specific fecundity for these faster-growing fish. This suggests an energy allocation protocol favouring growth over reproduction in these long-lived animals. Rockfishes have late recruitment to fisheries (ages 10–15), and the detection time for results of management actions is equally long. Their vulnerability to overfishing means that indices of population changes, more representative of fishing effects than the catch rate index presently used, are required. Reproductive value indices are shown to be extremely sensitive and continuous with population abundance changes. Their incorporation into monitoring programs would permit more timely evaluation of management actions. Management policies developed for shorter-lived species are shown to be inappropriate for rockfishes. The need for an improved match in the time frame of the species' life history, and that of management strategies, is stressed.
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  • 50
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    Environmental biology of fishes 35 (1992), S. 187-203 
    ISSN: 1573-5133
    Schlagwort(e): California ; Elasmobranchs ; Exploitation ; Fisheries ; Life history ; Tagging ; Triakidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis The age, growth, and sexual maturation of the leopard shark, Triakis semifasciata, from central California were studied. Growth band counts in vertebral centra of 162 leopard sharks produced von Bertalanffy growth curves with L∞, K. and to parameters of 1536 mm. 0.082, and -2.31, respectively, for both sexes combined. The L8 value for females (1602 mm TL) was slightly but insignificantly higher than for males (1499 mm TL), but the K and to values were almost identical. Seasonal changes in size modes of young-of-the-year leopard sharks, centrum edge characteristics, and growth and tetracycline mark-recapture from the field were used to validate annual deposition of vertebral centrum band pairs. Sexual maturity was evaluated by the gonads and presence of sperm and eggs; males mature at 7 yr and at about 63% of asymptotic length, and females mature at 10 yr, and at about 72% of asymptotic length. This slow growth, late maturity, and relatively low fecundity may increase their susceptibility to over-exploitation.
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  • 51
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    Environmental biology of fishes 45 (1996), S. 219-235 
    ISSN: 1573-5133
    Schlagwort(e): Ecology ; Behaviour ; Evolution ; Cichlids ; Fisheries ; Conservation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Ecological conditions in tropical lacustrine systems are considered by focusing on the evolution, maintenance, exploitation and vulnerability of fish communities in the African Great Lakes. The exceptionally high biodiversities in the littoral/sublittoral zones of the very ancient, deep, clear, permanently stratified rift lakes Tanganyika and Malawi, are contrasted with the simpler systems in their pelagic zones, also with biodiversity in the much younger, shallower Victoria, the world's largest tropical lake.
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  • 52
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    Animal cognition 1 (1998), S. 25-35 
    ISSN: 1435-9456
    Schlagwort(e): Key words Shape from shading ; Visual search ; Texture segregation ; Chimpanzees ; Humans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The perception of shape from shading was tested in two chimpanzees (Pan troglodytes) and five humans (Homo sapiens), using visual search tasks. Subjects were required to select and touch an odd item (target) from among uniform distractors. Humans found the target faster when shading was vertical than when it was horizontal, consistent with results of previous research. Both chimpanzees showed the opposite pattern: they found the target faster when shading was horizontal. The same difference in response was found in texture segregation tasks. This difference between the species could not be explained by head rotation or head shift parallel to the surface of the monitor. Furthermore, when the shaded shape was changed from a circle to a square, or the shading type was changed from gradual to stepwise, the difference in performance between vertical and horizontal shading disappeared in chimpanzees, but persisted in humans. These results suggest that chimpanzees process shading information in a different way from humans.
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  • 53
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    Environmental biology of fishes 23 (1988), S. 141-154 
    ISSN: 1573-5133
    Schlagwort(e): Cyanide ; Diversity ; Development ; Ecology ; Environment ; Fisheries ; Pollution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis The biological diversity and productivity of Philippine coral reefs are threatened by siltation, destructive fishing methods, coral and shell collecting and overfishing. Destructive fishing includes: the widespread, illegal use of explosives; poisons such as sodium cyanide; muro-ami and kayakas fishing; and trawling. The recent decline in catch rates threatens the livelihood of 700 000 near-shore subsistence fishermen who catch 55% of the total landings. The new government under Corazon Aquino wishes to protect the marine environment through the creation of a viable marine conservation management plan, enforcement of existing laws and through cooperation between government, non-government and international agencies to provide education and research. The Department of Agriculture, which has the authority for fisheries, has designated the International Marinelife Alliance as the lead non-government agency involved with fund raising, net-training and finding alternatives to destructive fishing methods.
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  • 54
    ISSN: 1573-5133
    Schlagwort(e): Cyprinids ; Ethiopia ; Morphotypes ; Food-niche ; Biodiversity ; Feeding ; Evolution ; Fisheries ; Resource partitioning ; Piscivory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis In October–December 1990, the large barbs (Barbus) that contribute more than 35% of the catch in lake Tana (northern Ethiopia) were studied. Previous authors (Rüppell 1837, Boulenger 1902,1911, Bini 1940) described from 6 to 23 (sub)species for the lake. Banister (1973) lumped all of these into one subspecies: Barbus intermedius intermedius Rüppell,1837. We found that the Lake Tana Barbus could be readily categorized in at least 13 discrete morphotypes, some of which were already distinguished by local fishermen. None of the known descriptions are adequate to distinguish the barbs unambiguously, which is important for monitoring and management of developing fisheries. Intermediates between morphotypes were rare (〈 10%). By applying canonical discriminant analysis on a set of 17 morphometric characters (including some directly associated with feeding) our initial morphotype-distinction was confirmed. Also, differences between the morphotypes in distribution, related to depth and substratum were found, as well as differences in intestinal contents, a key to the food-niche. The high number of piscivorous morphotypes (8 out of 13) was striking as piscivory is relatively rare among cyprinids. Piscivory was found to be highly correlated with morphological (feeding related) characters. The presence of discrete morphotypes, that also differ in food-niche and distribution, strongly suggests that several distinct populations exist, that may be (partly or completely) reproductively segregated. Knowledge about these populations, that may represent separate units of fish stock, is of crucial importance for the management of sustainable fisheries and protection of the biodiversity in Lake Tana. It is possible that several species or even a unique cyprinid species flock are present, that urgently need protection.
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  • 55
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    Environmental biology of fishes 27 (1990), S. 303-308 
    ISSN: 1573-5133
    Schlagwort(e): Fish introductions ; Africa ; Cichlids ; Barbus ; Haplochromis ; Lake management ; Fisheries
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Cyprinid fishes apparently constituted the major part of the original fish fauna in Lake Luhondo, Rwanda, at least until 1934. At that time only three species, all cyprinids, were known from the lake:Barbus neumayeri, a small barbel, very common in the lake (described from the lake asBarbus luhondo) and two larger cyprinid species:Barbus microbarbis andVaricorhinus ruandae. These two large species were probably not very common in the lake. Between 1935 and 1938 some youngTilapia were introduced into Lake Luhondo. Since then and certainly since 1952 the large cyprinids seem to have disappeared completely from the lake. The smallBarbus neumayeri has become extremely rare; at present it survives only in some small tributaries of the lake. In the lake itselfTilapia andHaplochromis species are now the dominant fauna. A survey of the available information is given.
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  • 56
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    Environmental biology of fishes 43 (1995), S. 381-391 
    ISSN: 1573-5133
    Schlagwort(e): Fisheries ; Irrigation ; Reproductive seasonality ; Sarotherodon galilaeus ; Species richness ; Water quality
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis A preliminary study of the ecology and commercial fish catches was carried out in the Toho-Todougba, Ahouangan and Dati lakes (1500 ha) in southern Benin (West Africa) over a period of 18 consecutive months. Water quality, species richness, and the reproductive biology of the dominant species, Sarotherodon galilaeus, were examined. Unlike Lagoon Toho-Todougba, lakes Ahouangan and Dati are less favourable for fish production because of their high total iron content and their relative low pH. The study revealed the existence of 19 species belonging to eleven (11) families: 16 species in Lagoon Toho-Todougba,12 in Lake Ahouangan, and 7 in Lake Dati. Lakes Ahouangan and Dati had a relatively high faunal similarity whereas Lagoon Toho-Todougba exhibited a relatively low faunal similarity with the former systems. In Lagoon Toho-Todougba, six cichlid species were the most important component of the fishery: Sarotherodon galilaeus, Tilapia guineensis, T. zillii, T. mariae, Chromidotilapia guntheri, Hemichromis fasciatus. Three catfish species Chrysichthys auratus, Clarias agboyiensis, and Clarias lazera were harvested in low abundances. Some other fish, such as Polypterus senegalus senegalus, Protopterus annectens and Heterotis niloticus were captured sporadically, with H. niloticus appearing more consistently in catches than the others. Although not abundant, Gymnarchus niloticus and the African pike, Hepsetus odoe, were almost always present in the catches. Ctenopoma kingsleyae appeared only in Ahouangan. Some predatory species, such as Notopterus afer and Xenomystus nigri, are encountered only in lakes Ahouangan and Dati. In Lagoon Toho-Todougba, Sarotherodon galilaeus had a sex ratio (♂: ♀) of 0.49:1, and size at maturation was estimated as 12.3 cm TL. The spawning period extended from May to September with the peak occurring in July. Fecundity was correlated to log-body length (r = 0.74) and log-body weight (r = 0.76). Fish catches were estimated at 389 kg ha−1 year−1; about 73% of which was Sarotherodon galilaeus. The overexploitation of juvenile fish and the use of this lagoon for the irrigation of palm tree plantations have reduced fish recruitment and mean size.
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  • 57
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    Environment, development and sustainability 2 (2000), S. 277-304 
    ISSN: 1573-2975
    Schlagwort(e): Systems of Knowledge ; Local Knowledge ; Fisheries ; Resource Management
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik , Sociologie
    Notizen: Abstract During the last 20 years, the existence of rich systems of local knowledge, and their vital support to resource use and management regimes, has been demonstrated in a wide range of biological, physical and geographical domains, such as agriculture, animal husbandry, forestry and agroforestry, medicine, and marine science and fisheries. Local knowledge includes empirical and practical components that are fundamental to sustainable resource management. Among coastal-marine fishers, for example, regular catches and, often, long-term resource sustainment are ensured through the application of knowledge that encompasses empirical information on fish behaviour, marine physical environments, fish habitats and the interactions among ecosystem components, as well as complex fish taxonomies. Local knowledge is therefore an important cultural resource that guides and sustains the operation of customary management systems. The sets of rules that compose a fisheries management system derive directly from local concepts and knowledge of the resources on which the fishery is based. Beyond the practical and the empirical, it is essential to recognise the fundamental socio-cultural importance of local knowledge to any society. It is through knowledge transmission and socialisation that worldviews are constructed, social institutions perpetuated, customary practices established, and social roles defined. In this manner, local knowledge and its transmission, shape society and culture, and culture and society shape knowledge. Local knowledge is of great potential practical value. It can provide an important information base for local resources management, especially in the tropics, where conventionally-used data are usually scarce to non-existent, as well as providing a shortcut to pinpoint essential scientific research needs. To be useful for resources management, however, it must be systematically collected and scientifically verified, before being blended with complementary information derived from Western-based sciences. But local knowledge should not be looked on with only a short-term utilitarian eye. Arguments widely accepted for conserving biodiversity, for example, are also applicable to the intellectual cultural diversity encompassed in local knowledge systems: they should be conserved because their utility may only be revealed at some later date or owing to their intrinsic value as part of the world's global heritage. At least in cultures with a Western liberal tradition, more than lip-service is now being paid to alternative systems of knowledge. The denigration of alternative knowledge systems as backward, inefficient, inferior, and founded on myth and ignorance has recently begun to change. Many such practices are a logical, sophisticated and often still-evolving adaptation to risk, based on generations of empirical experience and arranged according to principles, philosophies and institutions that are radically different from those prevailing in Western scientific circles, and hence all-but incomprehensible to them. But steadfastly held prejudices remain powerful. In this presentation I describe the 'design principles' of local knowledge systems, with particular reference to coastal-marine fishing communities, and their social and practical usefulness. I then examine the economic, ideological and institutional factors that combine to perpetuate the marginalisation and neglect of local knowledge, and discuss some of the requirements for applying local knowledge in modern management.
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  • 58
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 395-411 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The design and implementation of software for real-time spectral analysis on an IBM 1130 with 8k core is described. The procedures for estimation of coherence and cross-spectra are discussed in detail.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 59
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 381-394 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The Fast Fourier Transform is employed as a method of Laplace transform inversion to solve problems in the civil engineering fields of visco-elasticity and hydrology. When these problems are accurately represented by a linear time-invariant model, it is shown that the Fast Fourier Transform inversion procedure is often more accurate than standard convolution and inversion techniques. The speed and accuracy of solution resulting from this application of the Fast Fourier Transform is illustrated by referring to case studies solved on an IBM 1130 computer, model 3D processor with 32K memory.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 427-439 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Stress fields near crack tips in an elastic body can be specified by the stress intensity factors which are closely related to the stress singularities arising from the crack tips. These singularities, however, cannot be represented exactly by conventional finite element models. A new method for the analysis of stresses around cracks is proposed in this paper on the basis of the superposition of analytical and finite element solutions. This method is applied to several two-dimensional problems whose solutions are obtained analytically, and it is shown that their numerical results are in excellent agreement with analytical ones. Sufficiently accurate results can be obtained by the conventional finite element analysis with rather coarse mesh subdivision. Computational efforts are then considerably reduced compared with other methods.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 447-447 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 62
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 454-456 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 63
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 456-456 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 467-473 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A generalized variational principle is presented, which leads to a modified finite element approach for three-dimensional field problems. Both, potential function and velocity field, are approximated by expansions which are continuous across the inter-element boundaries. The rapid convergence of this mixed model is shown by two examples.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 65
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 497-509 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A computer program for the in-core solution of large, sparse, unsymmetric systems of linear equations is presented in this paper. The program employs elimination techniques for solution of systems of linear equations. A limited number of zeros is stored and trivial arithmetic is by-passed to preserve computer storage and to reduce the time required for solution. Several techniques for selecting the pivotal elements are discussed and their effect on accuracy and computational time are examined.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 66
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 521-527 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Numerical methods are used to investigate the two-dimensional motion of a viscous incompressible fluid impulsively started past a flat plate of finite breadth at zero incidence to the uniform motion of the fluid at large distances from the plate. A step by step integration in time of Helmholtz's vorticity equation is used for Reynolds numbers 10-500.The magnetohydrodynamic case is also considered with the applied magnetic field at infinity parallel to the uniform stream and the non-conducting plate. Results for the Magnetic Reynolds number 50 and infinite, Viscous Reynolds number 50 and 0≤β≤2, where β is the ratio of the square of the Alfvén speed to the square of the main stream velocity, are presented.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 67
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 6 (1973), S. 608-608 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 68
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 43-55 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A new family of triangular finite elements is described, useful for solving the axisymmetric vector Helmholtz equation, and a variety of scalar Helmholtz equation problems which lead to generalized Bessel equations of some order m. This family is similar in principle to the scalar axisymmetric Helmholtz elements derived earlier, but requires both reformulation of its describing equations and corresponding new universal element matrices, for successful computational implementation. The necessary formulation is given in this paper. Matrix elements to the sixth-order inclusive have been calculated and extensively tested computationally.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 69
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 57-67 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The criteria for stability of the explicit finite difference solution of the one-dimensional, transient, conduction heat transfer problem with both radiant and convection heat transfer at the boundaries are considered in this paper. These criteria are governed by an inequality set from a functional relationship between the newly calculated and the old temperature at each node.From the node with the most stringent criteria, it is shown that setting the coefficient of the old temperature equal to zero in the governing difference equation is not sufficient for a general criterion. On the other hand, setting the derivative of the new temperature with respect to the old temperature equal to zero in the governing difference equation presents a simple, straightforward technique for obtaining a sufficient condition for a stable system. It is further shown that the second law of thermodynamics, written in explicit finite difference form, does present a necessary criterion for stability. However, the second law, because it is in the form of an inequality, does not present as simple a criterion as the derivative method does.The specific problem studied is a finite thickness slab, initially at a uniform temperature, but instantaneously subjected to both radiation and convection on its two surfaces. Temperature profiles were calculated on a digital computer and are presented in dimensionless graphical form over a range of five dimensionless parameters. A plot that relates stability to the maximum time-step size for the entire range of practical conditions of radiation numbers is also presented.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973) 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 71
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 117-124 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A theorem expressing geometric conditions necessary and sufficient for the stiff stability of a linear multistep method is obtained. A corollary to this theorem provides sufficient conditions for stiff stability, for the class of algorithms characterized by a single essential root. By applying the Schur-Cohn criterion and employing a computerized algebraic manipulation program, the result provides a first step towards an exhaustive search technique for determining a continuum of members of this class.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 175-183 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A method is described for the solution of large sets of sparse equations arising in structural analysis. This method, called partial elimination, combines the concepts of elimination and iteration in such a way that good convergence rates can be obtained using a computer storage space not much greater than that required for other iterative methods.
    Zusätzliches Material: 5 Ill.
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  • 73
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 211-223 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A survey of recent developments in sparse matrix technology is presented. Two fundamental areas are reviewed: 1.Sorting and reordering techniques by which the non-zero elements of a given sparse matrix can be rearranged to obtain a form which leads to more efficient computations.2.Direct methods for solving systems of linear equations and computing inverses.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 63-87 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The finite element method is applied to the stability analysis of structural systems subject to non-conservative forces. The development of the method is general, but the specific application considered here is the stability of thin-walled members subject to follower forces. The method predicts the type of instability, whether it be buckling or flutter. Example problems, for which exact solutions are known, illustrate the accuracy and convergence characteristic of the finite element formulation.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 240-240 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 76
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 155-173 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The present investigation examines the multibar truss optimization problem in the context of a general class of unconstrained optimization procedures in conjunction with various types of penalty function transformations. Specifically, the problem is transformed into a series of unconstrained minimization problems using the penalty function techniques of Heaviside and SUMT. These are solved using the methods of Rosenbrock (orthogonal directions), Powell (conjugate directions) and Nelder-Mead (Simplex). This resulted in many cases in substantial improvements being recorded over previously reported data. The paper includes a comparative study of the synthesis based on these procedures.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 77
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 103-117 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The application of the finite element rank force method for the dynamic analysis of redundant structures is presented. The applied loading consists of discrete and distributed loads. Both forced and free vibrations are considered, the latter yielding latent vectors corresponding to dynamic redundancies.It is shown that the dynamic properties of an element are given by a static flexibility matrix, an inverse mass matrix, a damping parameter and a displacement vector representing the effect of the applied distributed loading.
    Zusätzliches Material: 5 Ill.
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  • 78
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 119-129 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A stiffness matrix for a finite element having the planform of an annular segment is derived using the displacement approach. Numerical problems involved in the derivation are discussed and rapid convergence to exact solutions is demonstrated on three sample problems. It is concluded that the new element will be of great value to engineers concerned with the analysis of slabs of bridge decks curved in plan.
    Zusätzliches Material: 8 Ill.
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  • 79
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 89-101 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The point matching numerical method and its generalization, the method of boundary point least squares, have been successfully applied to numerous boundary value and eigenvalue problems. The present paper demonstrates the application of these techniques to problems in the micromechanics of fibrous composite materials, i.e. determination of elastic moduli and stress concentrations for parallel-fibre materials which are loaded transversely with respect to the fibres. The solution technique utilizes exact solutions of the governing equations of plane elasticity for each component fibre and its surrounding matrix material in a typical repeating section of the composite material. The continuity conditions for stresses and displacements between fibre and matrix and the repeatability conditions at the boundary of the repeating section are satisfied approximately in a pointwise manner. Some special numerical techniques which were found to be particularly useful in applying the point matching method to these problems are delineated. The method is demonstrated for composite materials having circular, elliptical and square fibres in regular, staggered arrays. Numerical results are given which show the accuracy of the method as well as stress concentration and composite elastic moduli data.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 80
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 131-144 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper discusses the mathematical foundations of a technique that has been used extensively in structural optimization.1-6 Two basic problems are considered. The first of these is the concave programming problem which consists of finding the global minimum of ‘piece-wise concave functions’ on ‘piece-wise concave sets’. Since any function can be approximated by a piece-wise concave function, this method could in principle be used to find the global minimum in non-convex optimization problems. The second one is the piece-wise linear programming problem in which the objective function is convex and piece-wise linear. The iterative method outlined for handling this problem is shown to be much more efficient than the standard simplex method of linear programming.
    Zusätzliches Material: 13 Ill.
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  • 81
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 149-149 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 82
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 461-477 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Computer-oriented mesh generators, which serve as pre-processors to finite element programs, have recently been developed by several investigators to alleviate the frustration and to reduce the amount of time involved in the tedious manual subdividing of a complex structure into finite elements. Our purpose here is to describe how the techniques of bivariate ‘blending-function’ interpolation, which were originally developed for, and applied to, geometric problems of computer-aided design and numerically controlled machining of free-form surfaces such as automobile exterior panels, can be adapted and applied to the problems of mesh generation for finite element analyses. We concentrate attention on the problem of curvilinearly co-ordinating simply connected planar domains R by constructing invertible maps of the unit square S ≡[0, 1] × [0, 1] onto R. Extensions of the methods described herein to shells in 3-space is straightforward and is illustrated by a practical example taken from the automobile industry. Analogous mesh generators for three-dimensional solids can be developed on the basis of the trivariate ‘blending-function’ formulae found at the end of the second section.
    Zusätzliches Material: 15 Ill.
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  • 83
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 154-154 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 84
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 309-323 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Various solutions of laminated plates by the finite element method are analysed. An efficient solution of skew (or rectangular) laminated plates with small effect of σz and ∊z stress and strain components is developed. It can be used with an arbitrary number of layer elements (sub-elements) in different plate elements. Some remarks to the possible modification of solution are presented. Numerical examples with a short discussion and conclusions complete the paper.
    Zusätzliches Material: 12 Ill.
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  • 85
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The hybrid-element concept and the complex variable technique have been adopted for constructing a special super-element to be used jointly with conventional finite elements for the analysis of elastic stress intensity factors for plane cracks. The use of the complex variable technique permits the proper consideration of the stress intensity at the crack tip, and it also leads to very efficient programming. The use of such a super-element in the finite element solution has been shown to be highly accurate when only a very coarse element mesh is used near the crack.
    Zusätzliches Material: 5 Ill.
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  • 86
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 345-355 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Consider a solid heat conductor with a non-linear constitutive equation for the heat flux. If the material is anisotropic and inhomogeneous, the heat conduction equation to be satisfied by the temperature field θ(x, t) is, \documentclass{article}\pagestyle{empty}\begin{document}$$ \rho c\frac{{\partial \theta }}{{\partial t}} = {\rm div}({\rm L}(\theta,{\rm x})[{\rm grad}\theta]) + q $$\end{document} Here L(θ, x) [grad θ] is a vector-valued function of θ, x, grad θ which is linear in grad θ, In the present paper, the application of the finite element method to the solution of this class of problems is demonstrated. General discrete models are developed which enable approximate solutions to be obtained for arbitrary three-dimensional regions and the following boundary and initial conditions: (a) prescribed surface temperature, (b) prescribed heat flux at the surface and (c) linear heat transfer at the surface. Numerical examples involve a homogeneous solid with a dimensionless temperature-diffusivity curve of the form κ = κ0(l + σT). The resulting system of non-linear differential equations is integrated numerically.
    Zusätzliches Material: 6 Ill.
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  • 87
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 405-408 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Several formulas are presented for the numerical integration of a function over a triangular area. The formulas are of the Gaussian type and are fully symmetric with respect to the three vertices of the triangle.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 45-54 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper deals with a finite element formulation and solution of the boundary value problem of a concentrated force acting on a semi-infinite micropolar solid. A stiffness matrix is derived for a flat micropolar rectangular element in a plane state and use is made of this element to solve the case of the semi-infinite micropolar solid both in a state of plane stress and plane strain. An immediate application of the plane strain case is the important practical problem of a long line load acting on a soil mass which may be simulated as a micropolar body.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 111-117 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper presents an extension to the Matrix Transfer Method which gives quadratic convergence to a natural frequency from within a range on either side.The method is described and illustrated by application to: 1A torsional vibration problem, and2A lumped mass beam vibration problem.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 90
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 139-165 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A finite element formulation is presented for the equations governing the steady thermohydrodynamic behaviour of liquid lubricated bearings. This formulation permits application of the iterative solution scheme to bearings of arbitrary geometry.A generalized Reynolds equation resulting from the combination of the mass and momentum conservation equations is cast into variational form and used to derive general finite element equations. The method of weighted residuals with Galerkin's criterion is used to generate finite element matrix equations for the thermal energy equation. In addition to the finite element formulation, a discussion of appropriate finite difference techniques is also given for problems without complex geometry.As an example, the formulations are applied to obtain numerical solutions for a three-dimensional sector thrust bearing operating in the thermohydrodynamic regime. Pressure, velocity and temperature distributions are give, and the thermohydrodynamic solutions are compared with the results of classical isothermal theory.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 91
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 203-209 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 92
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 215-225 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The development of a general quadratic multilayer plate element is presented for the analysis of arbitrarily layered curved plates. In the formulation, each layer of the multilayer plate can have different orthotropic properties and can deform locally. Examples of bending problems are presented which demonstrate the applicability of the formulation.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 93
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 249-269 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A structural optimization problem is considered in which the design requirements include restrictions on the strength, stability, frequency and flutter characteristics of the structure. One of the central concerns of this phase of the work has been to overcome the problems inherent in analysing the dynamic and aeroelastic behaviour of structures with many degrees of freedom. The multiweb delta wing structure under supersonic flight conditions is the model upon which this exploratory study is based. The finite element idealization, with three different kinds of elements, is used to model the wing structure. The constant stress triangular plate elements, the rectangular shear panels and the pin-jointed bar elements are used to represent, respectively, the cover skins, webs and stringers of the wing structure. The design problem is formulated as a minimum weight optimization problem and is solved by using non-linear programming techniques. Computationally efficient schemes are developed for the necessary derivatives of the behaviour constraints. Numerical examples are presented to illustrate the feasibility and the computational effectiveness of the method.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 94
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 311-321 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 95
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 209-212 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 96
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 8 (1974), S. 214-214 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 97
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 275-290 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The solution of plate and shell problems by an independent specification of slopes and middle surface displacements is attractive due to its simplicity and ability of reproducing shear deformation. Unfortunately elements of this type are much too stiff when thickness is reduced.In an earlier paper a derivation of such an element was presented1 which proved very successful in ‘thick’ situations. Here a very simple extension is made which allows the element to be economically used in all situations.The improved flexibility is achieved simply by reducing the order of numerical integration applied to certain terms without sacrificing convergence properties. The process is of very wide applicability in improvement of element properties.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 98
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971) 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 99
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 295-296 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 100
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 3 (1971), S. 299-315 
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A system of finite element shell analysis codes, called SABOR/DRASTIC, is used to analyse a complex two-layered shell of revolution under static and dynamic asymmetric loads. The dynamic analysis is compared with experimentally measured response. In this linear elastic analysis, emphasis is placed on the inherent flexibility of the finite element method in modelling the complex structural geometry of a given test specimen. Static studies, which involve variations in important shell parameters, and dynamic studies, which provide a successful correlation with experiment, are used to illustrate both the detail and the generality with which shell analyses may now be performed with confidence.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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