标签：Digest 相关文章
Farewell to Arms 对扶手说再见 Good afternoon, this is your captain speaking. We are at cruising altitude and will be in flight for another three hours, so youd better get comfortable. That means figuring out who gets the arm rest you, or your n
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A Stationary Satellite, part 2 A geostationary satellite orbitsthe planet at the same rate as the planet rotates, so the satellite is always over the same patch of ground. Cool! you say. Id like to have one of those about twenty feet over my house. S
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A Stationary Satellite, part 1 Some of the best devices in science have been anticipated by science fiction writers years before they existed. Occasionally a writer comes up with an idea that can be put into practice within their lifetime! Such is th
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What Are Reflexes? If youve ever blinked at a sudden light, jerked your hand away from something hot, or jumped at a loud noise, then you know that these are not actions we consciously plan. Rather, they happen involuntarily. Such sudden, unconscious
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Everyone knows the story of the Titanic, the great ocean liner that struck an iceberg and sank to the bottom of the Atlantic. Less widely known is the icebergs story: where did it come from, and how did it get in the way of the ship? Although the vas
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In the early 1800s, a French physician named Ren Laennec had a dilemma. He needed to listen to the heart sounds of a young woman with signs of heart disease. But the only method of listening to heart sounds known to Western medicine at the time was s
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Scientists have searched for the origins of human speech in the hoots, grunts, and other vocalizations made by primates. It would seem to make sense, after all, that such sounds may be related to the more varied and articulated sounds we humans make.
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The Mathematics Of Middle-Age Spread Lets say youre an 18 year old male who runs every other day, logging 12 miles a week. Now fast-forward to your late 40s. Your eating habits are the same. To maintain your high school weight, how many miles a week
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Why refrigerators hum? Why refrigerators hum，on toay's moment of science.On the recent program we have discussed how fluorocarboncoolant cools your food by coming to a boil in coils hidden in your fridge. How is this possible? When you boil water o
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Why do Stradivarius violin s sound so good? 为什么史特拉第瓦里小提琴声音那么美妙？ A:What did i tell you？ B:You're right Yaoyao.This is a beautiful piece. A:It should be. B:What's so special about Stradivarius violin s ? A:Thats
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Bradycardia Don: Yal, isn't normal heart rate somewhere between sixty to one hundred beats per minute？ Yal: That's right, Don. Why? D: This would be the one time you don't correct me. My heart rate is only 44 beats per minute. That means I have bra
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Are Tanning Beds Safe? Millions of people go to tanning salons, some to get a base tan before they go away on a beach vacation. The idea of the base tan is that it will protect you from burning on your sun excursion, so that what you end up with is a
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As the Sun Turns 太阳也在自转？ Everyone knows that the earth turns. As a matter of fact, the sun turns too. Altough a lot of people don't realize it. Im not talking about being in orbit , nowthe earth definitely orbit s the sun and not the ot
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Why is it that you cant put down hydrogen gas? If you had a big balloon full of hydrogen gas, like the first gondola balloons pioneered in 18th-century France, youd find that it rises in the air quite dramatically. You know that a piece of wood will
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每次生病了，家里人最多说的一句话就是不吃药怎么行？。可是，有的时候吃药不一定就对身体有好处，反而有可能会帮助病原体攻击我们的身体。今天我们来了解了解一种新的理论达尔文医
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You Snooze or You Lose 几乎每个人在忙碌了一天之后，都要香香地睡上一觉。当然也有活了一辈子不 睡觉的人，但那是极个别的。人要睡觉是一种生理反应，是大脑神经活动的一部分， 是大脑皮质
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Summer Breeze, Makes Me Feel Fine 风是大家最熟悉的自然现象，要了解风的形成必须了解包围着地球的大气的运动。大气的流动也像水流一样是从压力高处往压力低处流。太阳能正是形成大气压差的原
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Better Than Barney 某天夜里，你一觉醒来发现电视机忘了关，节目却已播完，电视屏幕上嘶嘶地闪着雪花，也许你不会想到，再普通不过的雪花噪音竟包含来自137亿年前宇宙大爆炸的遗物微波背景
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Fatherless Honeybee s How male honeybee s can be without fathers? The reason lies in whats called a haploidiploid system of sex determination. Approximate ly one-fifth of the animal kingdom, including ants and wasp s , use this system. What it boils
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Acid Water Yal: What are you doing outside, Don? It's about to rain. Don: I'm setting out bottles. Y: I can see that. But why? D: For my new business venture. Bottled rainwater! Y: As in living plastic bottles out in the rain and then selling them as
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