【英语时差8,16】婴儿牙牙学语

Perhaps the baby isnt hearing properly, or perhaps the problem is cognitive. Or, as is sometimes the case, the babys parents arent speaking to the baby enough. Because experts believe that while some capacity for language is ingrained, learning how t

【英语时差8,16】动物界的染色体有何不同？2

But whats true for mammals isnt always true for the rest of the animal kingdom. The sex of baby birds is also determined by two different sex chromosomes, but in birds, its the male that has two of the same-shaped sex chromosomes and the female that

【英语时差8,16】动物界的染色体有何不同？

In mammals, the sex of a baby is determined by the combination of chromosomes it inherits from its parents. Nearly every cell in a male body has two different sex chromosomesone is shaped like an X and one is shaped like a Y. Females also have two se

【英语时差8,16】如何界定性别？2

Another sexual difference among mammals that doesnt hold with other animals is size. In most mammals the male is larger than the female, but in most other animals where there are two distinct sexes, the female is the larger one. Today scientists defi

【英语时差8,16】什么是卟咻症？

The vampire is the stuff of the great horror stories. However, a recent textbook by geneticist John Jenkins suggests that Bram Stokers legend of the vampire, Dracula, may have had its basis in a very real disease that prevents some people from gettin

【英语时差8,16】抗生素历史2

Since that time, scientists have found that numerous species of fungi produce chemicals to destroy bacteria and that bacteria even produce chemicals that destroy other bacteria. Antibiotics are relatively new in modern medicine, but the earliest medi

【英语时差8,16】抗生素历史

When you take an aspirin, a decongestant, or a muscle relaxant, the drug youre taking was probably made by a chemist combining a specific mixture of chemicals. Microscopic Fungi And Bacteria Antibiotics, on the other hand, are chemicals produced by m

【英语时差8,16】土星上真的有生命存在？

Acetylene and hydrogen molecules are disappearing from the atmosphere of Saturns moon, Titan. Its a mystery befitting Sherlock Holmes investigative skills, a mystery NASA scientists hope to crack. About fifty percent larger than Earths moon, Titan is

【英语时差8,16】伽利略—现代科学之父2

Galileo, however, used one of the earliest telescopes to look at Jupiter. He noticed that Jupiter has moons going around it. Apparently everything in the cosmos didnt have to go around the earth! Perhaps, Galileo said, it just looks like everything m

【英语时差8,16】伽利略—现代科学之父

What makes Galileo a science hero? For one thing, he moved human knowledge forward against outstanding prejudice and even persecution. Back in 1616, when Galileo argued that Copernicus had been right in suggesting the earth moves around the sun, he w

【英语时差8,16】微波炉如何加热食物？2

Microwaves heat water by jerking the water molecules around, so to speak. Each water molecule has a slight positive electric charge on one side and a slight negative charge on the other. As microwaves pass by, they exert forces on those charges, firs

【英语时差8,16】雪会说话？2

Snowflakes are small ice crystals. Snowflakes near the ir melting temperature can, through hand pressure, be made to fuse into a snowball by a process of melting and re-freezing. The snow yields to pressure gently and progressively and doesnt make so

【英语时差8,16】雪会说话？

Probably all, or nearly all, who have experienced a cold winter, are familiar with the cheery cry of the snow as it is pressed against a hard surface by the steel tire of a wagon, for instance, or even onto a pavement by the heels of ones boots. Thos

【英语时差8,16】有机蔬菜真的更健康吗？

Every time i go to the grocery stores，i consider buying Organic vegetables because they are supposed to be healthier or something，but they are also moreexpensive. So is it worth it to pay more for the supposed health benefits? Well, it might be w

【英语时差8,16】空中舞蹈

By bending arms and legs or angling her bodypresenting more or less surface area to the groundshe can change her rate of fall, slowing or speeding up her terminal velocity around ten or twenty miles per hour. To fall as fast as two hundred miles per

【英语时差8,16】青霉素的历史2

In 1928, Alexander Fleming was studying the bacterium, Staphylococcus, when some of the bacteria became contaminated with Penicillium fungus and stopped growing. Fleming decided that some chemical produced by the Penicillium fungus must be stopping t

【英语时差8,16】钱能买到一切?2

For example, spending money on things, like a new car or big flat screen TV, may give you a happiness bump at first. But its only temporary. Because we very quickly get used to even our coolest, most expensive possessions and soon barely notice them.

【英语时差8,16】糖为什么会溶解？

Did you ever wonder why sugar dissolves in a cup of coffee? Why not have the sugar just float in the middle of the cup, without dissipating into the coffee? Its because of the way water molecules interact with molecules in other substances. A water m

【英语时差8,16】大脑与手2

When people lose a hand, the part of the brain dedicated to that area receives no input at all. It becomes inactive. But the areas around it are still getting signals all the time. Some of those signals seem to leak over into the unused area. Just by

【英语时差8,16】绿色植物能预知未来？

The scientists guessed that the new seedlings were sensing the presence of neighboring plants by detecting the characteristic color of light reflected sideways from leaves of the neighboring plants. That characteristic color contains a very small amo