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The new order of aves, Gansuiformes, is established on the basis of the fossil specimens,including a tibiotarsus and a tarsometatarsus with four complete digits derived from the LowerCretaceous of Yumen, Gansu Province. The new bird probably represents the oldest one incontinental deposits. As Archaeopteryx is now considered as the ancestor of all landbirds,Gansus, the new bird is supposed to be the ancestor of shorebirds and waterbirds. Gansui-formes is similar to Charadriformes and some waterbirds in certain characters. 相似文献
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简要介绍现代酸碱理论的建立及其基本概念。现代酸碱理论包括了Brφnsted-Lowry酸碱理论、Lewis酸碱理论、HSAB理论和超酸理论。举例介绍了与物理有机化学、有机合成、有机催化等领域相关的现代酸碱理论的广泛应用。 相似文献
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甘肃早白垩世鸟化石兼论早期鸟类的进化 总被引:3,自引:0,他引:3
本文记述了产自甘肃玉门早白垩世地层中鸟类一新目——甘肃鸟目(Gansuifor-mes,Order,nov.)这是已知陆相地层中最早的鸟类. 始祖鸟(Archaeopteryx)是所有陆地鸟类的祖先,但对水鸟类和滨岸鸟类的起源,多限于推测,缺乏可靠依据.但甘肃鸟后肢下部的构造,显示了滨岸鸟类和水鸟类的相似性质,因此,它可能是它们的直系祖先。 相似文献
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