祖国力学事业辛勤的耕耘者——恭贺挚友伟长先生九秩华诞

<正> 今年正值我的老朋友钱伟长先生九十华诞,我愿在此向他表示最诚挚的祝贺,祝愿他健康长寿、老当益壮、诸事顺遂! 我与伟长先生的相识、相知可追溯到半个多世纪之前. 1946年初我赴美留学, 2月间到了加州理工学院的喷气推进研究室(JPL),那时在Th.von Karman教授周围可谓人才济济,特别是集中着几位出类拔萃的中国青年学者:钱学森、钱伟长、郭永怀、林家翘等等,我很快就与他们熟悉了.青年钱伟长给我留下了

mtDNA Data Indicate a Single Origin for Dogs South of Yangtze River, Less Than 16,300 Years Ago, from Numerous Wolves

There is no generally accepted picture of where, when, and how the domestic dog originated. Previous studies of mitochondrial DNA (mtDNA) have failed to establish the time and precise place of origin because of lack of phylogenetic resolution in the so fa