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排序方式: 共有237条查询结果,搜索用时 62 毫秒
171.
Peacock JA Cole S Norberg P Baugh CM Bland-Hawthorn J Bridges T Cannon RD Colless M Collins C Couch W Dalton G Deeley K De Propris R Driver SP Efstathiou G Ellis RS Frenk CS Glazebrook K Jackson C Lahav O Lewis I Lumsden S Maddox S Percival WJ Peterson BA Price I Sutherland W Taylor K 《Nature》2001,410(6825):169-173
The large-scale structure in the distribution of galaxies is thought to arise from the gravitational instability of small fluctuations in the initial density field of the Universe. A key test of this hypothesis is that forming superclusters of galaxies should generate a systematic infall of other galaxies. This would be evident in the pattern of recessional velocities, causing an anisotropy in the inferred spatial clustering of galaxies. Here we report a precise measurement of this clustering, using the redshifts of more than 141,000 galaxies from the two-degree-field (2dF) galaxy redshift survey. We determine the parameter beta = Omega0.6/b = 0.43 +/- 0.07, where Omega is the total mass-density parameter of the Universe and b is a measure of the 'bias' of the luminous galaxies in the survey. (Bias is the difference between the clustering of visible galaxies and of the total mass, most of which is dark.) Combined with the anisotropy of the cosmic microwave background, our results favour a low-density Universe with Omega approximately 0.3. 相似文献
172.
J. M. Stark S. K. Jackson S. Taylor I. Davies J. L. Harwood 《Cellular and molecular life sciences : CMLS》1990,46(5):472-474
Summary The effects of endotoxin on mouse liver phospholipid fatty acid composition have been investigated. Administration of endotoxin fromSalmonella abortus equi led to a decrease in the polyunsaturated fatty acid content of livers from mice sensitized with Bacille Calmette Guérin (GCG). The content of arachidonic acid fell significantly in both the phosphatidylcholine and phosphatidylinositol fractions whereas in the phosphatidylethanolamine fraction the linoleic acid content was significantly reduced. The polyunsaturated fatty acids were replaced by increased amounts of oleic acid and palmitic acid, leading to a reduction in the polyunsaturated to saturated fatty acid ratio. 相似文献
173.
I J Jackson 《Nature》1984,309(5971):751-752
174.
11-(R)-2H porphobilinogen, stereospecifically labelled with deuterium in the aminomethylene group has been incorporated into protoporphyrin-IX by haemolysates of chicken erythrocytes. High field NMR spectroscopy confirms that the overall biochemical process is stereospecific, deuterium being retained at the alpha-, gamma- and delta-meso positions and lost from the beta-meso position. 相似文献
175.
Localization of clathrin light-chain sequences mediating heavy-chain binding and coated vesicle diversity 总被引:3,自引:0,他引:3
F M Brodsky C J Galloway G S Blank A P Jackson H F Seow K Drickamer P Parham 《Nature》1987,326(6109):203-205
At least four distinct forms of clathrin light chains are found in mammalian cells. This molecular variability derives from tissue-specific patterns of expression of LCa and LCb genes. Sequence analysis shows an overall homology of 60% between LCa and LCb and the presence of brain-specific insertion sequences. These findings suggest that the different light chains have both shared and specialized functions. To address this question we have used a panel of monoclonal antibodies to identify two structurally and functionally distinct regions in the clathrin light-chain sequences. One region (residues 158-208) is exposed in native clathrin structures (triskelions and coated vesicles) and includes the brain-specific insertion sequences. The second region (residues 93-157), which is cryptic in native clathrin structures, is involved in binding the clathrin heavy chain and contains the region of strongest homology with intermediate filament proteins. 相似文献
176.
We develop a model to forecast the Federal Open Market Committee's (FOMC's) interest rate setting behavior in a nonstationary discrete choice model framework by Hu and Phillips (2004). We find that if the model selection criterion is strictly empirical, correcting for nonstationarity is extremely important, whereas it may not be an issue if one has an a priori model. Evaluating an array of models in terms of their out‐of‐sample forecasting ability, we find that those favored by the in‐sample criteria perform worst, while theory‐based models perform best. We find the best model for forecasting the FOMC's behavior is a forward‐looking Taylor rule model. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
177.
D. E. Cook J. D. Jackson M. R. Past C. M. Lang L. P. Bullock 《Cellular and molecular life sciences : CMLS》1984,40(8):840-841
Summary Both sexes of spontaneously diabetic guinea pigs exhibit hyperinsulinemia (>4-fold normal). This diabetic state is associated with the inhibition of hepatic drug metabolism in males but not females.Supported in part by NIH Grants AM 21282 from the NIAMDD and RR00469 from the DRR 相似文献
178.
179.
180.
Molecular species of the urobilins 总被引:2,自引:0,他引:2