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排序方式: 共有195条查询结果,搜索用时 15 毫秒
111.
112.
Andrew JG Simpson 《Genome biology》2000,1(1):reports411.1-reports4112
A meeting report of the sessions on human, eukaryotic and bacterial genome sequencing at the American Society for Microbiology and Institut Pasteur joint conference: Genomes 2000 International Conference on Microbial and Model Genomes, Paris, April 11-15, 2000 相似文献
113.
Parallels between the discrete group-testing model and some closely-related continuous models are elucidated. It is shown that in both the discrete and continuous cases, the maximum likelihood estimators may suffer from similar lack of robustness. Isotonic regression and maximum likelihood estimation were therefore compared for a modified group testing model. 相似文献
114.
Diving ducks use their webbed feet to provide the propulsive force that moves them underwater. To hold position near the bottom while feeding, ducks paddle constantly to resist the buoyant force of the body. Using video sequences from two orthogonal cameras we reconstructed the 3-dimensional motion of the feet through water and estimated the forces involved with a quasi-steady blade-element model. We found that during station holding, near the bottom, ducks use drag based propulsion with the webbed area of the foot moving perpendicular to the trajectory of the foot. The body was pitched at 76±3.47° below the horizon and the propulsive force was directed 26±1.9° ventral to the body so that 98% of the propulsive force in the sagittal plane of the duck worked to oppose buoyancy. The mechanical work done by moving both feet through a paddling cycle was 1.1±0.2 J which was equivalent to an energy expenditure of 3.7±0.5 W to hold position while feeding at 1.5 m depth. We conclude that in shallow water the high energetic cost of feeding in ducks is due to the need to paddle constantly against buoyancy even after reaching the bottom. The mechanical energy spent on holding position near the bottom, while feeding, is approximately 2 fold higher than previous estimates that were made for similar bottom depths but based on the presumed motion of the body instead of motion of the feet. 相似文献
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Edward J. Land Tulsi Mukherjee A.John Swallow J.Malcolm Bruce 《Archives of biochemistry and biophysics》1983,225(1):116-121
Pulse radiolysis of aqueous solutions containing adriamycin and redox indicators of known one-electron reduction potential (E1) shows that its E1 at pH 7 is ?328 mV (vs NHE). The variation E1 with pH in the range 6–12 shows that the net charge on the semiquinone at pH 7 is zero. As well as the pKa values of 2.9 and ≥ 14 established independently, the semiquinone has a pKa close to 9.2. The new data enable the structure and likely reactivity of the semiquinone to be specified. 相似文献
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In most people worldwide intestinal lactase expression declines in childhood. In many others, particularly in Europeans, lactase
expression persists into adult life. The lactase persistence phenotype is in Europe associated with the −13910*T single nucleotide
variant located 13,910 bp upstream the lactase gene in an enhancer region that affects lactase promoter activity. This variant
falls in an Oct-1 binding site and shows greater Oct-1 binding than the ancestral variant and increases enhancer activity.
Several other variants have been identified very close to the −13910 position, which are associated with lactase persistence
in the Middle East and Africa. One of them, the −14010*C, is associated with lactase persistence in Africa. Here we show by
deletion analysis that the −14010 position is located in a 144 bp region that reduces the enhancer activity. In transfections
the −14010*C allele shows a stronger enhancer effect than the ancestral −14010*G allele. Binding sites for Oct-1 and HNF1α
surrounding the −14010 position were identified by gel shift assays, which indicated that −14010*C has greater binding affinity
to Oct-1 than −14010*G. 相似文献
120.
Cécile Duclairoir Poc Anne Groboillot Olivier Lesouhaitier Jean-Paul Morin Nicole Orange Marc JG Feuilloley 《BMC research notes》2011,4(1):503