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邓昭镜 《西南师范大学学报(自然科学版)》1988,(4)
一维聚合链可以用一维振子链来模拟.其中联接振子而组装链的键可以分为主键和次键.一维振子链的非线性过程要受主键或次键的非线性过程所控制,本文讨论了在主键或次键的非线性作用下所引起的一维振子链的非线性过程.在一定条件下,我们可以得到解析的孤子解. 相似文献
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Hinch AG Tandon A Patterson N Song Y Rohland N Palmer CD Chen GK Wang K Buxbaum SG Akylbekova EL Aldrich MC Ambrosone CB Amos C Bandera EV Berndt SI Bernstein L Blot WJ Bock CH Boerwinkle E Cai Q Caporaso N Casey G Cupples LA Deming SL Diver WR Divers J Fornage M Gillanders EM Glessner J Harris CC Hu JJ Ingles SA Isaacs W John EM Kao WH Keating B Kittles RA Kolonel LN Larkin E Le Marchand L McNeill LH Millikan RC Murphy A Musani S Neslund-Dudas C Nyante S Papanicolaou GJ Press MF Psaty BM 《Nature》2011,476(7359):170-175
Recombination, together with mutation, gives rise to genetic variation in populations. Here we leverage the recent mixture of people of African and European ancestry in the Americas to build a genetic map measuring the probability of crossing over at each position in the genome, based on about 2.1 million crossovers in 30,000 unrelated African Americans. At intervals of more than three megabases it is nearly identical to a map built in Europeans. At finer scales it differs significantly, and we identify about 2,500 recombination hotspots that are active in people of West African ancestry but nearly inactive in Europeans. The probability of a crossover at these hotspots is almost fully controlled by the alleles an individual carries at PRDM9 (P?value 10(-245)). We identify a 17-base-pair DNA sequence motif that is enriched in these hotspots, and is an excellent match to the predicted binding target of PRDM9 alleles common in West Africans and rare in Europeans. Sites of this motif are predicted to be risk loci for disease-causing genomic rearrangements in individuals carrying these alleles. More generally, this map provides a resource for research in human genetic variation and evolution. 相似文献
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Human gut microbiome viewed across age and geography 总被引:2,自引:0,他引:2
Yatsunenko T Rey FE Manary MJ Trehan I Dominguez-Bello MG Contreras M Magris M Hidalgo G Baldassano RN Anokhin AP Heath AC Warner B Reeder J Kuczynski J Caporaso JG Lozupone CA Lauber C Clemente JC Knights D Knight R Gordon JI 《Nature》2012,486(7402):222-227
Gut microbial communities represent one source of human genetic and metabolic diversity. To examine how gut microbiomes differ among human populations, here we characterize bacterial species in fecal samples from 531 individuals, plus the gene content of 110 of them. The cohort encompassed healthy children and adults from the Amazonas of Venezuela, rural Malawi and US metropolitan areas and included mono- and dizygotic twins. Shared features of the functional maturation of the gut microbiome were identified during the first three years of life in all three populations, including age-associated changes in the genes involved in vitamin biosynthesis and metabolism. Pronounced differences in bacterial assemblages and functional gene repertoires were noted between US residents and those in the other two countries. These distinctive features are evident in early infancy as well as adulthood. Our findings underscore the need to consider the microbiome when evaluating human development, nutritional needs, physiological variations and the impact of westernization. 相似文献
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Yang J Manolio TA Pasquale LR Boerwinkle E Caporaso N Cunningham JM de Andrade M Feenstra B Feingold E Hayes MG Hill WG Landi MT Alonso A Lettre G Lin P Ling H Lowe W Mathias RA Melbye M Pugh E Cornelis MC Weir BS Goddard ME Visscher PM 《Nature genetics》2011,43(6):519-525
We estimate and partition genetic variation for height, body mass index (BMI), von Willebrand factor and QT interval (QTi) using 586,898 SNPs genotyped on 11,586 unrelated individuals. We estimate that ~45%, ~17%, ~25% and ~21% of the variance in height, BMI, von Willebrand factor and QTi, respectively, can be explained by all autosomal SNPs and a further ~0.5-1% can be explained by X chromosome SNPs. We show that the variance explained by each chromosome is proportional to its length, and that SNPs in or near genes explain more variation than SNPs between genes. We propose a new approach to estimate variation due to cryptic relatedness and population stratification. Our results provide further evidence that a substantial proportion of heritability is captured by common SNPs, that height, BMI and QTi are highly polygenic traits, and that the additive variation explained by a part of the genome is approximately proportional to the total length of DNA contained within genes therein. 相似文献
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