科學(xué)60秒: “身負(fù)重任”的中世紀(jì)盔甲

Medieval armor certainly looks heavy. And now researchers have demonstrated how the protection might have put its wearers at a heavy disadvantage on the battlefield. An armored combatant in the...

美文背誦——睡眠的進(jìn)化

Evolution of SleepSleep is very ancient. In the electroencephalographic sense we share it with all the primates and almost all the other mammals and birds: it may extend back as far as the reptil...

背誦美文——?jiǎng)游锏牧_盤(pán)

Animals’ CompassesResearchers have found that migrating animals use a variety of inner compasses to help them navigate. Some steer by the position of the Sun. Others navigate by the stars. Some ...

經(jīng)濟(jì)：7870億美元的經(jīng)濟(jì)刺激法案之爭(zhēng)將結(jié)束

經(jīng)濟(jì)：7870億美元的經(jīng)濟(jì)刺激法案之爭(zhēng)將結(jié)束The battle over the 787-billion-dollar stimulus bill officially ends after President’s Day. President Obama says he will sign the bill into law in Denver ...