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排序方式： 共有409条查询结果，搜索用时 15 毫秒
31.
Söllner C Burghammer M Busch-Nentwich E Berger J Schwarz H Riekel C Nicolson T 《Science (New York, N.Y.)》2003,302(5643):282-286
The stone-like otoliths from the ears of teleost fishes are involved in balance and hearing and consist of calcium carbonate crystallites embedded in a protein framework. We report that a previously unknown gene, starmaker, is required in zebrafish for otolith morphogenesis. Reduction of starmaker activity by injection of modified antisense oligonucleotides causes a change in the crystal lattice structure and thus a change in otolith morphology. The expression pattern of starmaker, along with the presence of the protein on the growing otolith, suggest that the expression levels of starmaker control the shape of the otoliths. 相似文献
32.
Wild maize, agricultural maize, and associated Manihot fossil polleni indicative of early agriculture after about 7300 years ago have been discovered in the Gatun basin, Panama. The course of risinig sea level in the Canal Zone during the past 11,300 years is calculated. 相似文献
33.
Berger M 《Science (New York, N.Y.)》2007,316(5821):49
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Three oak stands (Quercus petraea and Quercus robur) in the Weinviertel, Lower Austria, located along a distance gradient from a lime quarry, were studied to determine the effects of basic aerosols on the deposition of ammonium, nitrate and sulfate. Higher concentrations of limestone aerosols in the vicinity of the quarry are suggested by higher Ca2+ fluxes and pH in throughfall and precipitation. The ammonium/nitrate ratio in throughfall decreases with distance from the quarry, though monitoring of NH3 and NO2 concentrations in the air with passive samplers shows the opposite trend. These findings support the theory of discrimination against NH3 in dry deposition due to the presence of Ca 2+ particles on leaf surfaces resulting from limestone aerosols. Higher sulfate deposition near the quarry is consistent with higher atmospheric SO2 concentrations and co-deposition between calcium and sulfate. 相似文献
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