Temperatures of a Close Earth Satellite Due to Solar and Terrestrial Heating     

Wilson RH 《Science (New York, N.Y.)》1958,127(3302):811-812

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Sign Change of Poisson's Ratio for Carbon Nanotube Sheets     

Hall LJ  Coluci VR  Galvão DS  Kozlov ME  Zhang M  Dantas SO  Baughman RH 《Science (New York, N.Y.)》2008,320(5875):504-507

Most materials shrink laterally like a rubber band when stretched, so their Poisson's ratios are positive. Likewise, most materials contract in all directions when hydrostatically compressed and decrease density when stretched, so they have positive linear compressibilities. We found that the in-plane Poisson's ratio of carbon nanotube sheets (buckypaper) can be tuned from positive to negative by mixing single-walled and multiwalled nanotubes. Density-normalized sheet toughness, strength, and modulus were substantially increased by this mixing. A simple model predicts the sign and magnitude of Poisson's ratio for buckypaper from the relative ease of nanofiber bending and stretch, and explains why the Poisson's ratios of ordinary writing paper are positive and much larger. Theory also explains why the negative in-plane Poisson's ratio is associated with a large positive Poisson's ratio for the sheet thickness, and predicts that hydrostatic compression can produce biaxial sheet expansion. This tunability of Poisson's ratio can be exploited in the design of sheet-derived composites, artificial muscles, gaskets, and chemical and mechanical sensors.  相似文献   

Band gap fluorescence from individual single-walled carbon nanotubes   总被引：1，自引：0，他引：1  

O'Connell MJ  Bachilo SM  Huffman CB  Moore VC  Strano MS  Haroz EH  Rialon KL  Boul PJ  Noon WH  Kittrell C  Ma J  Hauge RH  Weisman RB  Smalley RE 《Science (New York, N.Y.)》2002,297(5581):593-596

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.  相似文献   

SCIENTIFIC NOMENCLATURE     

Harper RH 《Science (New York, N.Y.)》1902,16(400):354

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THE CARNEGIE TECHNICAL UNIVERSITY     

Thurston RH  Alderson VC  Gray T  Johnson JB 《Science (New York, N.Y.)》1901,14(341):41-45

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Serum lipids in adult twins     

OSBORNE RH  ADLERSBERG D 《Science (New York, N.Y.)》1958,127(3309):1294

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PERSISTENT MITOSIS OF TRANSFUSED HOMOLOGOUS LEUKOCYTES IN CHILDREN RECEIVING ANTILEUKEMIC THERAPY     

LEVIN RH  WHANG J  TJIO JH  CARBONE PP  FREI E  FREIREICH EJ 《Science (New York, N.Y.)》1963,142(3597):1305-1311

Temporary homologous bone marrow grafts were observed in three patients with acute leukemia, receiving intensive antileukemic treatment, following transfusion of peripheral blood cells from donors with chronic myelocytic leukemia. Persistent mitosis of the transfused cells, containing the Philadelphia chromosome marker, were detected by cytogenetic techniques 19, 39, and 52 days after transfusion.  相似文献   

Carbon-14 Tetrachloride Produced by Neutron Irradiation of Aniline-and Pyridine-CCl4 Solutions     

Hein RE  Setser DW  Terhaar CJ  Chang SC  McFarland RH  Hansen MF 《Science (New York, N.Y.)》1957,125(3240):195-196

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PHLOEM DEVELOPMENT AND BLOSSOMING     

Roberts RH  Wilton OC 《Science (New York, N.Y.)》1936,84(2183):391-392

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An iridium abundance anomaly at the palynological cretaceous-tertiary boundary in northern new Mexico     

Orth CJ  Gilmore JS  Knight JD  Pillmore CL  Tschudy RH  Fassett JE 《Science (New York, N.Y.)》1981,214(4527):1341-1343

An iridium abundance anomaly, with concentrations up to 5000 parts per trillion over a background level of 4 to 20 parts per trillion, has been located in sedimentary rocks laid down under freshwater swamp conditions in the Raton Basin of northeastern New Mexico. The anomaly occurs at the base of a coal bed, at the same stratigraphic position at which several well-known species of Cretaceous-age pollen became extinct.  相似文献