共查询到20条相似文献,搜索用时 31 毫秒
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C. Theodore Williams 《BMJ (Clinical research ed.)》1887,2(1409):1456-1457
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This paper explains the objectives of organising the symposium ‘The Other North Sea’. A major goal is the submission of the
conclusions and content of this symposium to the North Sea Task Force, an initiative of the Second Conference on the Protection
of the North Sea (London, 1987) which is responsible for preparing a Quality Status Report on the North Sea by mid-1993. The
conclusions and recommendations of the symposium are summarised and presented to the North Sea Task Force in connection with
the preparations for the 1993 Quality Status Report. The paper stresses the need to subdivide the North Sea into areas of
ecological entity and underlines the advantages of using diatom and meiofauna assemblages as indicators for present and past
environmental actors in sediment conditions. A plea is also made for the promotion of research to improve understanding of
disturbance of sensory perception and behaviour as an ecologically relevant early warning signal. The major role of fisheries
in inducing changes of seabird and harbour porpoise populations is highlighted. 相似文献
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Harvey Cushing 《BMJ (Clinical research ed.)》1922,1(3208):1001-1002
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The training and utilization of New Health Practitioners (NHP''s) has moved within a decade from a small tentative beginning in the mid-1960''s to a major health manpower policy issue. Its discussion transcends a number of important and emotionally charged areas including the role of various professions in providing health care services, the renaissance of primary care, the geographic and economic maldistribution of medical services, and the cost of care. It is valuable to highlight what is known, what is professed and what needs to be studied further about this issue. 相似文献
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The Weaker Sex? The Propensity for Male-Biased Piglet Mortality 总被引:1,自引:0,他引:1
For the most part solutions to farm animal welfare issues, such as piglet mortality, are likely to lie within the scientific disciplines of environmental design and genetic selection, however understanding the ecological basis of some of the complex dynamics observed between parent and offspring could make a valuable contribution. One interesting, and often discussed, aspect of mortality is the propensity for it to be sex-biased. This study investigated whether known physiological and behavioural indicators of piglet survival differed between the sexes and whether life history strategies (often reported in wild or feral populations) relating to parental investment were being displayed in a domestic population of pigs. Sex ratio (proportion of males (males/males+females)) at birth was 0.54 and sex allocation (maternal investment measured as piglet birth weight/litter weight) was statistically significantly male-biased at 0.55 (t35 = 2.51 P = 0.017), suggesting that sows invested more in sons than daughters during gestation. Despite this investment in birth weight, a known survival indicator, total pre-weaning male mortality was statistically significantly higher than female mortality (12% vs. 7% respectively z = 2.06 P = 0.040). Males tended to suffer from crushing by the sow more than females and statistically significantly more males died from disease-related causes. Although males were born on average heavier, with higher body mass index and ponderal index, these differences were not sustained. In addition male piglets showed impaired thermoregulation compared to females. These results suggest male-biased mortality exists despite greater initial maternal investment, and therefore reflects the greater susceptibility of this sex to causal mortality factors. Life history strategies are being displayed by a domestic population of pigs with sows in this study displaying a form of parental optimism by allocating greater resources at birth to males and providing an over-supply of this more vulnerable sex in expectation of sex-biased mortality. 相似文献
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W. H. B. Aikins 《CMAJ》1915,5(12):1045-1055
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Helga Kristin Hallgrimsdottir 《Evolutionary biology》2012,39(1):27-29
Metaphors and analogies have long been used as heuristic and explanatory devices in the sciences. This focal review comments
on the article "The Transmission of Genes and Culture: A Questionable Analogy" by Drs. Cladiere and Andre, and discusses the
usefulness of the GTM analogy for understanding the transmission of culture. 相似文献
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The initiation mess? 总被引:7,自引:3,他引:4
John Herrick Masamichi Kohiyama Tove Atlung & Flemming G. Hansen 《Molecular microbiology》1996,19(4):659-666
This review concerns the mechanisms which control initiation of chromosome replication in enterobacteria with respect to cell growth. Initiation control is commonly separated into positive and negative regulatory mechanisms. Four main points are advanced concerning these different aspects of initiation control. (i) The average concentration of the initiator protein DnaA is proportional to the origin concentration, i.e. the origin per cell mass ratio and, thus, inversely proportional to the very often used term of the 'initiation mass'. (ii) The time of initiation of chromosome replication in the cell cycle is set by DnaA protein accumulating to a threshold level, which in concert with a number of other factors allows for a co-operative formation of the initiation complex. (iii) The time of initiation is not determined by the interaction with these other factors or by the transient interaction between newly replicated origins ( oriC ) and the cell surface. (iv) The aberrant initiation phenotype observed in various mutants, including dnaA (ts) mutants, might be due to a defective pre-initiation DnaA– oriC interaction or it might be due to a defect in the protection of newly initiated origins from reinitiation. Many of these points are discussed and evaluated in view of recent developments concerning the regulation of chromosome replication in Escherichia coli 相似文献
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Ruth Müller Clare Hanson Mark Hanson Michael Penkler Georgia Samaras Luca Chiapperino John Dupré Martha Kenney Christopher Kuzawa Joanna Latimer Stephanie Lloyd Astrid Lunkes Molly Macdonald Maurizio Meloni Brigitte Nerlich Francesco Panese Martyn Pickersgill Sarah Richardson Joëlle Rüegg Sigrid Schmitz Aleksandra Stelmach Paula‐Irene Villa 《EMBO reports》2017,18(10):1677-1682
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