共查询到20条相似文献，搜索用时 30 毫秒
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Stokstad E 《Science (New York, N.Y.)》2000,289(5479):584
In the United States, about 150 police officers die every year in the line of duty, and government figures suggest that some 350 suspected criminals are justifiably killed in confrontations with police. Seeking lessons behind these gruesome statistics and other disturbing trends in violent behavior nationwide (see main text) are researchers at the Federal Bureau of Investigation. 相似文献
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Hewlett M 《Science (New York, N.Y.)》2007,316(5833):1843-1844
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Marshall E 《Science (New York, N.Y.)》1993,260(5116):1886-1888
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Balter M 《Science (New York, N.Y.)》1999,286(5440):660-662
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Kerr RA 《Science (New York, N.Y.)》2000,290(5492):697-698
Three researchers pondering what could be behind a roughly 1500-year cycle of warming and cooling are suggesting that it is a combination of two climate drivers, each too weak to have a large effect on its own. When a strictly periodic cycle teams up with just the right amount of thoroughly irregular noise, the combination could achieve "stochastic resonance" and set off the dramatic climate shifts of the last ice age--or the next, possibly human-triggered, Little Ice Age. No one is claiming the case is proven, but if true it will complicate predictions of future climate. 相似文献
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The means by which a pulsar might be detected in the remnant of supernova 1987a in the Large Magelanic Cloud is examined. One possibility is that the slower-than-radioactive decay typically seen in the type II light curves is itself the sign of powering by the underlying pulsar, with the decline representing not the spinning down of the pulsar but rather the declining nebular opacity that would allow increasing amounts of the energy to escape as gamma rays. The test of this hypothesis (if the supernova conforms to type II expectations) would be to look for the "missing" energy in the form of those gamma rays that escape from the remnant instead of powering it. 相似文献
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Taubes G 《Science (New York, N.Y.)》1993,261(5129):1670-1671
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Cohen J 《Science (New York, N.Y.)》1993,261(5129):1678-1679
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