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排序方式: 共有350条查询结果,搜索用时 156 毫秒
341.
Novel interleukin-2 receptor subunit detected by cross-linking under high-affinity conditions 总被引:74,自引:0,他引:74
M Sharon R D Klausner B R Cullen R Chizzonite W J Leonard 《Science (New York, N.Y.)》1986,234(4778):859-863
Interleukin-2 (IL-2) binds to both high- and low-affinity classes of IL-2 receptors on activated T lymphocytes. Only the high-affinity receptors are involved in receptor-mediated endocytosis and normally transduce the mitogenic signals of IL-2; however, the structural features distinguishing the high- and low-affinity receptors are unknown. When 125I-labeled IL-2 was chemically cross-linked to activated human T lymphocytes, two major bands were identified. First, as predicted, a 68- to 72-kilodalton band, consisting of IL-2 (15.5 kilodaltons) cross-linked to the IL-2 receptor (55 kilodaltons), was observed. Second, an unpredicted 85- to 92-kilodalton moiety was detected. This band was not present when IL-2 was cross-linked to transfected C127 cells, which exclusively express low-affinity receptors. The data presented are most consistent with the existence of a 70- to 77-kilodalton glycoprotein subunit (p70) which, upon associating with the 55-kilodalton low-affinity receptor (p55), transforms it into a high-affinity site. It is proposed that p55 and p70 be referred to as the alpha and beta subunits, respectively, of the high-affinity IL-2 receptor. 相似文献
342.
Benitez-Nelson CR Bidigare RR Dickey TD Landry MR Leonard CL Brown SL Nencioli F Rii YM Maiti K Becker JW Bibby TS Black W Cai WJ Carlson CA Chen F Kuwahara VS Mahaffey C McAndrew PM Quay PD Rappé MS Selph KE Simmons MP Yang EJ 《Science (New York, N.Y.)》2007,316(5827):1017-1021
Mesoscale eddies may play a critical role in ocean biogeochemistry by increasing nutrient supply, primary production, and efficiency of the biological pump, that is, the ratio of carbon export to primary production in otherwise nutrient-deficient waters. We examined a diatom bloom within a cold-core cyclonic eddy off Hawaii. Eddy primary production, community biomass, and size composition were markedly enhanced but had little effect on the carbon export ratio. Instead, the system functioned as a selective silica pump. Strong trophic coupling and inefficient organic export may be general characteristics of community perturbation responses in the warm waters of the Pacific Ocean. 相似文献
343.
Kim KC Reed CA Elliott DW Mueller LJ Tham F Lin L Lambert JB 《Science (New York, N.Y.)》2002,297(5582):825-827
Evidence for a three-coordinate silyl cation is provided by the crystal structure of [(Mes)3Si][H-CB11Me5Br6].C6H6 (where Mes is 2,4,6-trimethylphenyl). Free (Mes)3Si+ cations are well separated from the carborane anions and benzene solvate molecules. Ortho-methyl groups of the mesityl substituents shield the silicon atom from the close approach of nucleophiles, while remaining innocent as significant ligands themselves. The silicon center is three-coordinate and planar. The downfield 29Si nuclear magnetic resonance chemical shift in the solid state (226.7 parts per million) is almost identical to that in benzene solution and in "gas phase" calculations, indicating that three-coordination can be preserved in all phases. 相似文献
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The bioflocculant-producing potentials of a marine bacteria isolated from the bottom sediment of Algoa Bay was investigated using standard methods. The 16S rDNA sequence analysis revealed 98% similarity to that of Bacillus sp. HXG-C1 and the nucleotide sequence was deposited in GenBank as Bacillus sp. Gilbert with accession number . Bioflocculant was optimally produced when sucrose (72% flocculating activity) and ammonium chloride (91% flocculating activity) were used as sole sources of carbon and nitrogen, respectively; an initial pH 6.2 of the production medium; and Mg2+ as cation. Chemical analysis of the purified bioflocculant revealed the compound to be a polysaccharide. HQ537128相似文献
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Simon Marcel Pierre Knuth Dennis Böhm Leonard Wiltschka Katrin Schatz Marlene Düring Rolf-Alexander 《Journal of Soils and Sediments》2022,22(2):496-508
Journal of Soils and Sediments - Organochlorine pesticides (OCPs) like lindane and DDT have been used extensively after World War II until the 1990s. Still, residues of these pesticides can be... 相似文献
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