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正案例一从连黑三日谈极昼极夜章节内容:地球公转的意义之极昼极夜播放flash动画——太阳直射点的移动与昼夜长短变化。请同学们认真观察地球公转,昼半球和夜半球的交界线,也就是晨昏线是怎样移动的?学生:有时候晨昏线经过南北两极;有时候北极圈内全是白天,南极圈全是黑夜;有时候南极圈内全是白天,北极圈内全是黑夜。 相似文献
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The distributions and changes of dissolved organic carbon in the Prydz Bay and out open sea were investigated during CHINARE-15 ( the 15th Chinese National Antarctic Research Expedition). The results showed that the content of DOC was higher in the Prydz Bay and outer open sea compared to those typical of surface oceanic levels (70-80μM), average content of DOC in the surface water was 102.32 μM,the range was 68.23-125.92 μM. The vertical distribution of DOC in the water column was similar to many ocean sites, that is to say, the content of upper water is higher than deep water, a subsurface maximum persisted between 25-50 m. The DOC pool in the Prydz Bay were consisted with labile, semi-labile and refractory pools, in which refractory pools was mainly part. The concentration of refractory DOC was 92.34 and 76.89 μM in Prydz Bay and outer open sea, and account 77% and 82% for total DOC, respectively. 相似文献
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走进中山,感受南极圈内中国第一站如果从空中俯瞰拉斯曼丘陵,在南纬69°22'、东经76°23'位置的南极荒原上,你会发现一片红黄相间的建筑群在皑皑白雪之中显得格外鲜艳夺目。这里就是中国南极科考工作者心中的“家”,是他们的“圣地”——中国南极中山站。这里也是中国南极科考事业开始20年来,第一座也是唯一一座真正建立在南极圈内的考察站。从亚南极到东南极:艰难的建站历程中山站位于拉斯曼丘陵北端,面向普里兹湾,背靠埃默里冰架和格罗夫山脉。这里冬季最低气温可达零下33.6℃,连续极昼时间54天,连续极夜时间58天,最大风速43.6米/秒。虽然… 相似文献
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