共查询到20条相似文献,搜索用时 15 毫秒
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Renwick WH Smith SV Sleezer RO Buddemeier RW 《Science (New York, N.Y.)》2004,305(5690):1567; author reply 1567
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Brower AV 《Science (New York, N.Y.)》2004,303(5655):173; author reply 173
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Rougier GW Forasiepi AM Martinelli AG 《Science (New York, N.Y.)》2005,309(5740):1492; author reply 1492
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Arsenic mobility and groundwater extraction in Bangladesh 总被引:13,自引:0,他引:13
Harvey CF Swartz CH Badruzzaman AB Keon-Blute N Yu W Ali MA Jay J Beckie R Niedan V Brabander D Oates PM Ashfaque KN Islam S Hemond HF Ahmed MF 《Science (New York, N.Y.)》2002,298(5598):1602-1606
High levels of arsenic in well water are causing widespread poisoning in Bangladesh. In a typical aquifer in southern Bangladesh, chemical data imply that arsenic mobilization is associated with recent inflow of carbon. High concentrations of radiocarbon-young methane indicate that young carbon has driven recent biogeochemical processes, and irrigation pumping is sufficient to have drawn water to the depth where dissolved arsenic is at a maximum. The results of field injection of molasses, nitrate, and low-arsenic water show that organic carbon or its degradation products may quickly mobilize arsenic, oxidants may lower arsenic concentrations, and sorption of arsenic is limited by saturation of aquifer materials. 相似文献
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Van Oost K Govers G Quine TA Heckrath G 《Science (New York, N.Y.)》2004,305(5690):1567; author reply 1567
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Comment on "Ivory-billed woodpecker (Campephilus principalis) persists in continental North America"
Sibley DA Bevier LR Patten MA Elphick CS 《Science (New York, N.Y.)》2006,311(5767):1555; author reply 1555
We reanalyzed video presented as confirmation that an ivory-billed woodpecker (Campephilus principalis) persists in Arkansas (Fitzpatrick et al., Reports, 3 June 2005, p. 1460). None of the features described as diagnostic of the ivory-billed woodpecker eliminate a normal pileated woodpecker (Dryocopus pileatus). Although we support efforts to find and protect ivory-billed woodpeckers, the video evidence does not demonstrate that the species persists in the United States. 相似文献
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Bever GS Rowe T Ekdale EG Macrini TE Colbert MW Balanoff AM 《Science (New York, N.Y.)》2005,309(5740):1492; author reply 1492
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Comment on "Zircon thermometer reveals minimum melting conditions on earliest Earth" II 总被引:1,自引:0,他引:1
Nutman AP 《Science (New York, N.Y.)》2006,311(5762):779; author reply 779
Watson and Harrison (Reports, 6 May 2005, p. 841) interpreted low temperatures (approximately 700 degrees C) for Hadean zircons as evidence of the existence of wet, minimum-melting conditions within 200 million years of solar system formation. However, high-temperature melts (approximately 900 degrees C) are zircon-undersaturated and crystallize zircon only after substantial temperature drop during fractional crystallization. Zircon thermometry cannot distinguish between low- and high-temperature Hadean igneous sources. 相似文献
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Fujishima A 《Science (New York, N.Y.)》2003,301(5640):1673; discussion 1673
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Lackner KS 《Science (New York, N.Y.)》2003,301(5640):1673; discussion 1673
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W Bains 《Science (New York, N.Y.)》2012,337(6099):1173; author reply 1173
Grainger et al. (Reports, 13 April 2012, p. 245) suggest that baboons can discriminate words from nonwords on the basis of two-letter (bigram) frequencies. This ability can also be attributed to baboons being able to recognize specific letters (i.e., shapes) in specific positions in their four-letter words, without reference to letter or bigram frequencies. 相似文献
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酸性土壤有效砷提取方法研究 总被引:23,自引:5,他引:18
采用0.5mol·L-1NaHCO3(pH8.5),0.5mol·L-1NaH2PO4和0.1mol·L-1HCl等3种浸提剂,对福建省酸性水稻土和酸性菜地土壤有效砷的提取效果以及相关的提取条件进行了研究。结果表明,3种浸提剂所提取的土壤有效砷与作物可食用部分砷含量之间均存在显著相关,其中0.5mol·L-1NaH2PO4提取的有效砷与糙米和蔬菜地上部砷含量的相关性最高,相关系数分别是0.628和0.824,是三者中最佳的浸提剂。对NaH2PO4的提取条件的研究表明,在15∶1的液土比条件下以250r·min-1的速度振荡120min是最佳的酸性土壤有效砷的提取方法。 相似文献