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排序方式: 共有44条查询结果,搜索用时 15 毫秒
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Nadeau JH Balling R Barsh G Beier D Brown SD Bucan M Camper S Carlson G Copeland N Eppig J Fletcher C Frankel WN Ganten D Goldowitz D Goodnow C Guenet JL Hicks G Hrabe de Angelis M Jackson I Jacob HJ Jenkins N Johnson D Justice M Kay S Kingsley D Lehrach H Magnuson T Meisler M Poustka A Rinchik EM Rossant J Russell LB Schimenti J Shiroishi T Skarnes WC Soriano P Stanford W Takahashi JS Wurst W Zimmer A;International Mouse Mutagenesis Consortium 《Science (New York, N.Y.)》2001,291(5507):1251-1255
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Olga A. Kildisheva Todd E. Erickson David J. Merritt Matthew D. Madsen Kingsley W. Dixon Jacqueline Vargas Remy Amarteifio Andrea T. Kramer 《Strength and Conditioning Journal》2018,71(3):318-322
Seed dormancy can present a significant barrier to restoration outcomes in dryland systems. Physical and combinational (physical + physiological) dormancy are prevalent among seeds of many herbaceous perennials used in restoration of drylands throughout the western United States. Although many techniques designed to alleviate these dormancy traits exist, their efficacy is species specific, may result in embryo damage, and may have limited large-scale application. To identify the most effective means of dormancy alleviation with the potential to be used on an operational scale, we examined the effects of 16 temperature-based techniques (altering temperature and duration of wet heat, freezing and wet heat, and freeze-thaw cycles) and 6 abrasion-based techniques (altering pneumatic scarification length or using a single duration of manual scarification) on the enhancement of seed permeability among two physically dormant (western prairie clover [Dalea ornata {Douglas} Eaton & Wright] and Munro’s globemallow [Sphaeralcea munroana {Douglas} Spach]) and two combinationally dormant species (basalt milkvetch [Astragalus filipes Torr. ex A. Gray] and longspur lupine [Lupinus arbustus {Douglas} ex Lindl.]). We first assessed seed imbibition following exposure to all temperature- and abrasion-based techniques to identify those most successful at promoting seed permeability and then evaluated the effectiveness of those techniques through a series of germination experiments. For combinationally dormant species, we also tested whether exposure to GA3 enhanced germination. Abrasion-based techniques were more effective than temperature-based techniques at improving water uptake across all species. Pneumatic scarification significantly improved germination, but optimal treatment durations were species specific. GA3 did not enhance germination under the tested conditions. We conclude that pneumatic scarification is a fast, safe, and effective method for alleviating physical seed dormancy with a potential to be scaled up for operational use in restoration. 相似文献
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OBJECTIVES: To develop a composite index to describe the overall breast-feeding performance of infants<6 months of age; and, using this index, to identify the factors associated with poor breast-feeding practices and the association between breast-feeding and infant morbidity. DESIGN, SETTING AND SUBJECTS: The 2003 Demographic and Health Survey was a multi-stage cluster sample survey of 4320 households in Timor-Leste which covered 573 infants aged<6 months. Breast-feeding Performance Index (BPI) was constructed by allocating one point for each of seven infant feeding practices: first suckling within an hour of birth; absence of prelacteals; non-use of feeding bottles; current breast-feeding; not receiving liquids; not receiving formula or other milk; and not receiving solids in the last 24 hours. BPI was treated as the dependent variable in univariate and multivariate analyses to identify the factors associated with poor breast-feeding. RESULTS: Exclusive breast-feeding rate was 29.9%. The BPI (mean 4.4, standard deviation 1.77) was categorised as low, average and high according to tertiles. Multivariate analysis indicated that infants from the richest households were 1.70 (95% confidence interval (CI) 1.04-2.77) times more likely to have 'low BPI' than the poorest. Maternal BMI<18.5 kg m(-2) was predictive of poor breast-feeding (odds ratio=1.79; 95% CI 1.27-2.52). In the 'low' BPI group, the incidence of diarrhoea (13.4%) and acute respiratory infections (20.7%) during the previous two weeks was significantly higher than in 'average' (4.3 and 9.3%) and 'high' BPI groups (4.6 and 5.5%). CONCLUSIONS: Creating a composite index to assess the overall breast-feeding performance among infants<6 months of age is feasible. BPI can be effectively used to identify target groups for breast-feeding promotion interventions. 相似文献
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Flematti GR Goddard-Borger ED Merritt DJ Ghisalberti EL Dixon KW Trengove RD 《Journal of agricultural and food chemistry》2007,55(6):2189-2194
The butenolide, 3-methyl-2H-furo[2,3-c]pyran-2-one (1), has recently been identified as the germination stimulant present in smoke that promotes the germination of seeds from a wide range of plant species. In this paper, we describe the preparation of a number of analogues of 1 and compare their efficacy in promoting seed germination of three highly smoke-responsive plant species, Lactuca sativa L. cv. Grand Rapids (Asteraceae), Emmenanthe penduliflora Benth. (Hydrophyllaceae), and Solanum orbiculatum Poir. (Solanaceae). The results show that the methyl substituent at C-3 in 1 is important for germination-promoting activity while substitution at C-7 reduces activity. In contrast, bioactivity is mostly retained with analogues substituted at C-4 or C-5. 相似文献
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Judith L. Fisher William A. Loneragan Kingsley Dixon Julie Delaney Erik J. Veneklaas 《Biological conservation》2009,142(10):2270-2281
Relationships between fire history, vegetation structure and composition, and invasion by introduced plant species have received limited attention in Australian woodlands. A study in a Mediterranean, fire adapted urban Banksia woodland remnant in the biodiversity hotspot of southwest Australia investigated: (1) Have significant changes occurred in the woodland tree canopy between 1963 and 2000? (2) Do correlations exist between fire frequency and canopy cover? (3) If there is a difference in the vegetation composition of Banksia woodland invaded by the South African Ehrharta calycina (PCe) and Pelargonium capitatum (PCp) compared to largely intact remnants (GC)? and (4) Do correlations exist between vegetation condition, composition, fire frequency and invasion? Aerial photography, processed in a Geographical Information System, was used to establish fire history and changes in canopy cover over time (1963–2000). PCe and PCp sites experienced the greatest number of fires, with a net reduction in canopy cover in all areas experiencing four or more fires (60% of all woodlands). Frequent fire corresponded with a decline in native cover, richness and diversity, a shift from native to introduced species, changes in the relative importance of fire response categories, and loss of native resprouting shrub cover. Life forms of introduced species, which included no trees, shrubs and perennial sedges, contrasted strongly with those of native species, which had poor representation of annual and perennial grasses. Clear ecological and conservation consequences due to the loss of species diversity, changes in fire ecology and invasion have occurred in the Banksia woodlands. This study provides an understanding of the invasion process, enhancing conservation knowledge to improve the adaptive management of the key threatening process of invasion in biodiverse communities. 相似文献
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