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阿拉斯加北极熊、保护鼻子以及禽类的祖先---暴龙

kira86 于2008-06-03发布 l 已有人浏览
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Alaska Disputing Federal Move to List Polar Bears as Threatened迅雷专用高速下载 VOICE ONE:This is SCIENCE IN T
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Alaska Disputing Federal Move to List Polar Bears as Threatened


迅雷专用高速下载

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty.

VOICE TWO:


A polar bear in Alaska

And I'm Shirley Griffith. This week, we will tell about a decision by the United States federal government to protect polar bears. We will tell about a possible genetic link between farm birds and an ancient, meat-eating creature. And, we will have more first aid suggestions.

(MUSIC)

VOICE ONE:

America's northernmost(最北的) state is threatening legal action in an effort to prevent federal protection of the polar bear. Alaskan officials say there is not enough evidence that polar bears are threatened. They also say the federal listing would harm economic activities and development in the state.

Last month, the federal government identified polar bears as threatened under a wildlife law --  the  Endangered  Species  Act(美国的《濒危物种保护法》) . The polar bear is the first animal to gain such protection because of climate change.

VOICE TWO:

Polar bears live along the northern and northwestern coast of Alaska, in the Arctic Ocean.  Interior  Secretary  (美国内务部长)Dirk Kempthorne said the animals are being protected partly because a large amount of Arctic ice has melted. The polar bear needs this ice to survive. The interior secretary also said computer studies show that the melting will continue into the future.

But Alaskan officials said such studies are undependable.

A United States Geological Survey study last year estimated that polar bears could disappear from Earth by twenty fifty. About twenty thousand to twenty five thousand polar bears live in the Arctic. But most are in Canadian territory.

VOICE ONE:

Environmental activists had hoped that identifying the animal as threatened would result in carbon dioxide restrictions. But Mister Kempthorne said the government would not use the Endangered Species Act to limit gases from vehicles, power stations and other factories. He said a direct link could not be established between release of the gases and threat to polar bears.

In declaring protection for the bears, the interior secretary also announced a special rule. The rule will let exploration and drilling of oil continue in the Arctic. Mister Kempthorne said these activities do not harm polar bears.

(MUSIC)

VOICE TWO:

Last week, we talked about some common medical emergencies. We suggested how to deal with problems such as choking, accidental poisonings and severe bleeding. Today, we will explain how to treat another problem: bleeding from the nose.

Medical experts at America's Mayo Clinic say nosebleeds can end without too much worry, or they can be serious. The experts say children and young adults usually bleed from the septum(隔膜). The septum separates the two areas of tissue in the nose. This bleeding usually does not require medical attention.

VOICE ONE:

But a nosebleed in middle-aged or older adults can be coming from deep inside the nose. The problem can result from medical conditions including high blood pressure or hardening of the main blood passages. In some cases, the nose just starts bleeding for no clear reason. If you are a middle-aged or older adult with this condition, get medical help.

Also go to a doctor or hospital emergency room if any bleeding lasts longer than twenty minutes. The Mayo Clinic has the same advice if the nose starts bleeding after an accident, fall or blow.

VOICE TWO:

Here is what Mayo Clinic doctors suggest you do if you have a nosebleed: First, sit up and move forward from the middle of your body. That reduces the blood pressure in the nose. Sitting forward should keep you from swallowing blood that collects in your mouth. Use the thumb and the finger closest to the thumb to press inward on the outside of the nose. This finger is often called the index finger.

Breathe through your mouth. Keep doing this for five to ten minutes. It can often stop the blood from flowing. After the nosebleed has stopped, do not touch your nose or blow it. Make sure that your head is in a higher position than your heart.

VOICE ONE:

If the nosebleed should start again, breathe out strongly. Then treat both sides of your nose with a nose medicine that contains oxymetazoline. Press inward again on the outer surface of the nose with the thumb and index finger. Then, says the Mayo Clinic, you need to contact your doctor.

You also need a doctor if nosebleeds happen to you often. The doctor may advise cautery, a method that burns the blood vessel with electric current, silver nitrate or a laser. In addition, you need a doctor if you take blood-thinning drugs and have a nosebleed.

VOICE TWO:

Sometimes people get foreign objects in their noses. Children have been known to put anything from small pieces of food to medicine in the nasal passages. If that happens at your house, the Mayo Clinic says do not push at the object with any kind of tool. Tell the child to breathe through the mouth instead of the nose.

Have the child blow out the object softly, but not repeatedly. If only one side of the nose is affected, hold the other side closed. Then have the child blow out the affected side. If you see the object and can easily take hold of it with a tool, go ahead. But if all these attempts fail, get medical help.

(MUSIC)

VOICE ONE:

Finally, can you imagine taking a bite out of Tyrannosaurus(暴龙) Rex? T. Rex, as it was called, was that huge, fierce dinosaur often seen in films. The chickens people eat today do not look much like the ancient meat-eating animal. But evidence is increasing that T. Rex was the ancestor of the farm birds 禽类of today. The theory developed because the dinosaur and the chicken had similar bone structures.

Now, American scientists say they have confirmed the idea. Their study was published recently in Science magazine. The investigators said the gene structure of T. Rex was more like that of chickens than reptiles of today, like alligators. The gene structure of the T. Rex also was similar to that of the ostrich, a big bird that does not fly.

VOICE TWO:

The researchers were able to make those statements partly because of an event in two thousand three. At that time, John Horner of Montana State University found a T. Rex fossil in an area between the states of Montana and Wyoming. The fossil was removed from the bottom of what is called the Hell Creek Formation.

The dinosaur was not large, and appeared to be about eighteen years old when it died. It took three years for scientists from the Museum of the Rockies in Montana to get the bone out of the rock formation where it was buried. It was far from a road, and too heavy to be lifted by helicopter.

VOICE ONE:

Professor Horner says the scientists were forced to something that they always want to prevent. They had to break the bone into two pieces. But dividing it made possible the unlikely discovery of soft tissue.

Part of the leg bone was taken to dinosaur expert Mary Schweitzer of North Carolina State University. While examining it, she and her technical aide noted signs of soft tissue. This kind of tissue contains blood vessels. The technician, Jennifer Wittmeyer, did the tests repeatedly because Miz Schweitzer could not believe what she was seeing.

The soft tissues had lasted through sixty-eight million years. Scientists probably never had made such a discovery before, said Miz Schweitzer. Soft tissues usually disappear over time, while hard tissues like bones become fossils.

VOICE TWO:

John Asara and Lewis Cantley then processed the proteins. Both work at Harvard University Medical School and Beth Israel Deaconess Hospital in Massachusetts. Harvard University researcher Chris Organ compared the molecules of dinosaur protein with similar protein. The similar material came from many kinds of modern reptiles and birds.

Mister Organ was lead researcher. He said the researchers plan to continue their molecular comparisons. They say they now will study T. rex protein with reptiles and birds other than the chicken.

The researchers also studied material from another large prehistoric creature -- a mastodon. They found that it is similar to the modern elephant. This finding is not a surprise, because the elephant looks very similar to the mastodon.

(MUSIC)

VOICE ONE:

This SCIENCE IN THE NEWS program was written by Jerilyn Watson. Brianna Blake was our producer. I'm Bob Doughty.

VOICE TWO:

And I'm Shirley Grifith. Read and listen to our programs at www.en8848.com. Join us again at this time next week for more news about science in Special English on the Voice of America.

知识扩展:暴龙真相

暴龙,学名Tyrannosaurs Rex的意思是暴君蜥蜴,肉食性恐龙中出现最晚,也是最大型,最孔武有力的品种。暴龙可能是地球上有史以来最大的陆生肉食动物,六千五百万年前灭绝, 结束在白垩纪。暴龙的头部非常的巨大(长约1.2米)。强而有力的颚部上长有锯齿边缘的牙齿,庞大粗壮却像鸟类的两脚上,指头长有强力爪子。和粗壮的脚比较起来,暴龙的手臂小得与头骨的反比,比人类的手要短,根据古生物学家认为,这可能由于暴龙只用口捕腊,前肢绝少使用,因而渐渐变短变小,也因此演变成由后肢站立,前肢退化及后肢成为武器,因而演化成这种奇异的身体结构,暴龙虽然身躯庞大,骨骼却是空心的,而且头颅中有一些大而中空的洞,因而使得体重减轻,便于行走和捕腊。体长十四米,体高约五点五米,体重达七吨,暴龙的尾巴长又粗,看来是一个强而有力的攻防武器,大概常以后肢及尾巴为重心,因此推测后肢和尾部份肌肉相当结实,破坏力比龙卷风还强大!

一般来说,学者们相信暴龙是肉食性恐龙中最为残暴的恐龙,它出现的时间已经是恐龙时代的晚期,距离现在大约六千五百万年。暴龙的身体高达十四米,体重大约十吨,它的后脚十分粗大强壮,甚至能各自撑起一只具大的现生象。从暴龙的化石发现,它的每颗牙齿大小不一,有的牙齿长度,比人类的手掌还要长,有的小如人类尾指一节,牙齿由尖顶到基部,都有斜旋锯齿,其凶猛程度可见一斑,颚部强大惊人,是数十头湾鳄颚颔力量的总和,暴龙的头是所有恐龙中最大又最有力的,这种可怕的肉食性动物会用长着军刀般利齿的巨颚,狠狠地一口咬死猎物,接着扭转强壮的颈部,将嘴中的肉块撕扯下来。张开的血盆大口更是吓人,里面生着二排向内弯曲的锐利牙齿,每颗有二三十厘米长,一但被咬住,即使是身上有着坚韧骨质甲胄的大型草食性恐龙也会承受不住。

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