Elasmobranchs     

Nelson G 《Science (New York, N.Y.)》1979,205(4404):387

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Philip Handler: National Academy nominates a worldly "high priest"     

B Nelson 《Science (New York, N.Y.)》1968,162(857):981-984

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THE OCCURRENCE OF MOTTLED TEETH IN IOWA     

Ostrem CT  Nelson VE  Greenwood DA  Wilhelm HA 《Science (New York, N.Y.)》1932,76(1981):575-576

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THE CONSERVATION OF MARINE MAMMALS     

Nelson EW 《Science (New York, N.Y.)》1923,58(1495):135-136

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Disruption of the epithelial apical-junctional complex by Helicobacter pylori CagA     

Amieva MR  Vogelmann R  Covacci A  Tompkins LS  Nelson WJ  Falkow S 《Science (New York, N.Y.)》2003,300(5624):1430-1434

Helicobacter pylori translocates the protein CagA into gastric epithelial cells and has been linked to peptic ulcer disease and gastric carcinoma. We show that injected CagA associates with the epithelial tight-junction scaffolding protein ZO-1 and the transmembrane protein junctional adhesion molecule, causing an ectopic assembly of tight-junction components at sites of bacterial attachment, and altering the composition and function of the apical-junctional complex. Long-term CagA delivery to polarized epithelia caused a disruption of the epithelial barrier function and dysplastic alterations in epithelial cell morphology. CagA appears to target H. pylori to host cell intercellular junctions and to disrupt junction-mediated functions.  相似文献   

A viviparous pumpkin     

Nelson ET 《Science (New York, N.Y.)》1884,4(94):470-471

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WILBUR CLITONT KNIGHT     

Nelson A 《Science (New York, N.Y.)》1903,18(456):406-409

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The silica balance in the world ocean: a reestimate   总被引：8，自引：0，他引：8  

Tréguer P  Nelson DM  Van Bennekom AJ  Demaster DJ  Leynaert A  Quéguiner B 《Science (New York, N.Y.)》1995,268(5209):375-379

The net inputs of silicic acid (dissolved silica) to the world ocean have been revised to 6.1 +/- 2.0 teramoles of silicon per year (1 teramole = 10(12) moles). The major contribution (about 80 percent) comes from rivers, whose world average silicic acid concentration is 150 micromolar. These inputs are reasonably balanced by the net ouputs of biogenic silica of 7.1 +/- 1.8 teramoles of silicon per year in modern marine sediments. The gross production of biogenic silica (the transformation of dissolved silicate to particulate skeletal material) in surface waters was estimated to be 240 +/- 40 teramoles of silicon per year, and the preservation ratio (opal accumulation in sediment/gross production in surface waters) averages 3 percent. In the world ocean the residence time of silicon, relative to total biological uptake in surface waters, is about 400 years.  相似文献   

Intercalation of sea urchin proteins in calcite: study of a crystalline composite material     

Berman A  Addadi L  Kvick A  Leiserowitz L  Nelson M  Weiner S 《Science (New York, N.Y.)》1990,250(4981):664-667

Sea urchin skeletal elements are composed of single crystals of calcite. Unlike their synthetic counterparts, these crystals do not have well-developed cleavage and are consequently much more resistant to fracture. This phenomenon is due in part to the presence of acidic glycoproteins occluded within the crystals. By means of x-ray diffraction with synchrotron radiation, it is shown that the presence of the protein in synthetic calcite only slightly decreases the coherence length but significantly increases the angular spread of perfect domains of the crystals. In biogenic calcite, the coherence length is 1/3 to 1/4 as much as that in synthetic calcite and the angular spread is 20 to 50 times as wide. It is proposed that the presence of macromolecules concentrated at mosaic boundaries that are oblique to deavage planes is responsible for the change in fracture properties. These results may be important in the material sciences, because of the unusual nature of this material, namely, a composite based on the controlled intercalation of macromolecules inside single-crystal lattices.  相似文献   

Liver Tumors in Rats Fed Thiourea or Thioacetamide     

Fitzhugh OG  Nelson AA 《Science (New York, N.Y.)》1948,108(2814):626-628

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