共查询到20条相似文献,搜索用时 15 毫秒
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From an experiment in which corals are transplanted between two depths on a Panamanian coral reef, Baker infers that bleaching may sometimes help reef corals to survive environmental change. Although Baker's results hint at further mechanisms by which reef-building corals may acclimatize to changing light conditions, we do not consider that the evidence supports his inference. 相似文献
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In January of 2001 the superconductivity of the compound MgB2 with a critical temperature Tc of up to 39 K was discovered. This Tc is the highest in all intermetallic compound and alloy superconductors. MgB2 has a simple structure and its manufacturing capital cost is lower, therefore it could become a practical superconductor in the future. The recent progress is reviewed here which covers the progress in electronic structure, high Tc mechanism, superconducting parameters (Debye temperature, specific heat coefficient of electron, critical fields, coherent length, penetration depth, energy gap, critical current and relaxation rate of flux). Moreover the issue on power transmission is discussed. 相似文献
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Carroll SM 《Nature》2006,440(7088):1132-1136
It goes without saying that we are stuck with the Universe we have. Nevertheless, we would like to go beyond simply describing our observed Universe, and try to understand why it is that way rather than some other way. When considering both the state in which we find our current Universe, and the laws of physics it obeys, we discover features that seem remarkably unnatural to us. Physicists and cosmologists have been exploring increasingly ambitious ideas in an attempt to explain how surprising aspects of our Universe can arise from simple dynamical principles. 相似文献
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The anomaly of the recent increase in Atlantic major hurricane activity (MHA) is controversial. From a reconstruction of past MHA, Nyberg et al. conclude that the present activity is not unusual by comparison with that of the past 270 years. However, here I estimate the uncertainty of average MHA in the hurricane record before 1945 and show that the reconstruction of Nyberg et al. differs strongly from that record, and probably overestimates past MHA. Owing to this and further reasons, I question whether their reconstruction provides an accurate basis for conclusions about past MHA. 相似文献
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Is acidification still an ecological threat? 总被引:3,自引:0,他引:3
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