根据以下材料,回答题Stem Cell Therapy May Help Repair the HeartAccording to scientists in t - 试题答案网问答

第1题

根据下面材料，回答题。 Human Heart Can Make New CellsSolving a longstanding mystery, scien

根据下面材料，回答题。

Human Heart Can Make New Cells

Solving a longstanding mystery, scientists have found that the human heart continues to generate new cardiac cells throughout the life span, although the rate of new cell production slows with age.

The finding, published in the April 3 issue of Science, could open a new path for the treatment of heart diseases such as heart failure and heart attack, experts say.

"We find that the beating cells in the heart, cardiomyocytes, are renewed," said lead researcher Dr. Jonas Frisen, a professor of stem cell research at the Karolinska Institute in Stockholm, Sweden.

"It has previously not been known whether we were limited to the cardiomyocytes we are born with or if they could be renewed," he said.

The process of renewing these ceils changes over time, Frisen added. In a 20-year-old, about 1 percent of cardiomyocytes are exchanged each year, but the turnover rate decreases with age to only 0.45 percent by age 75.

"If we can understand how the generation of new cardiomyocytes is regulated, it may be potentially possible to develop pharmaceuticals that promote this process to stimulate regeneration after, for example, a heart attack," Frisen said.

That could lead to treatment that helps restore damaged hearts. "A lot of people suffer from chronic heart failure," noted co-author Dr.Ratan Bhardwaj, also from the Karolinska Institute.

"Chronic heart failure arises from heart cells dying," he said.

With this finding, scientists are "opening the door to potential therapies to having ourselves heal ourselves," Bhardwaj said. "Maybe one could devise a pharmaceutical agent that would make heart cells make new and more cells to overcome the problem they are facing."

But barriers remain. According to Bhardwaj, scientists do not yet know how to increase heart cell production to a rate that would replace cells faster than they are dying off, especially in older patients with heart failure. In addition, the number of new cells the heart produces was estimated using healthy hearts--whether the rate of cell turnover in diseased hearts is the same remains unknown.

The human heart stops producing cardiac cells____________. 查看材料

A.when a person is born

B.when a person becomes old

C.when a person gets sick

D.when a person dies

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第2题

根据下列材料请回答 16～22 题: 第 16 题 The 20 patients had stem cell injections inst

根据下列材料请回答 16～22 题:

根据下列材料请回答 16～22 题: 第 16 题 The 20 patients had stem

第 16 题 The 20 patients had stem cell injections instead of surgery.

根据下列材料请回答 16～22 题: 第 16 题 The 20 patients had stem

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第3题

根据材料，完成题。 Stem Cell Therapy May Help Repair the Heart According to scientists in

根据材料，完成题。

Stem Cell Therapy May Help Repair the Heart

According to scientists in the USA, stem cell therapy may one day be able to repair the hearts of people with heart failure.Researchers at Pittsburgh University School of Medicine examined 20 patients who had severe heart failure and were going to have surgery.

They injected stem cells into the parts of their hearts that were damaged. They then compared their hearts with those of people who had undergone surgery without having the stem cells injected into them (they had also suffered from severe heart failure ) . The patients who had the stem cells injected had hearts that were able to pump (用泵抽运) more blood than the others.

According to Professor Robert Kormos, one of the researchers, these results could revolutionize heart treatment. Although previous studies had indicated that there might be a benefit, this is the first study that has actually proved that stem cell therapy can help the failing heart work better.

All the patients in this study had hearts that could not pump blood properly. The scientists measured their ejection fraction (射血分数 ) . It is a measure of heart performance; you measure how much blood is being pumped out by the left ventricle (心室) .

Healthy people&39;s ejection fraction is about 55%. These patients had ejection fraction of under 35%. They all had by-pass surgery (搭桥手术) performed on them. Some of the patients had stem cells taken from their hip bones and injected into 25-30 sites in the damaged heart muscle. Six months later their ejection fraction rate was 46.1% while those who just had surgery but no stem cell injections averaged 37.2%.

Heart failure is a common problem all over the world.In the UK alone about 650,000 people suffer from heart failure every year. As the number of people suffering from heart failure increases in the word in general these findings are particularly significant.

Current treatments relieve the symptoms. This new stem cell therapy actually repairs the damaged muscle in the heart and has the potential of curing the disease.

The 20 patients had stem cell injections instead of surgery. 查看材料

A.Right

B.Wrong

C.Not mentioned

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第4题

根据以下材料，回答题Better Solar Energy Systems: More Heat， More LightSolar photovoltaic th

根据以下材料，回答题

Better Solar Energy Systems: More Heat， More Light

Solar photovoltaic thermal energy systems， or PVTs， generate both heat and electricity， but__________ （51） now they haven"t been very good at the heat-generating part compared to a stand-alone solar thermal collector. That"s because they operate at low temperatures to cool crystalline silicon solar cells，__________ （52） lets the silicon generate more electricity but isn"t a very efficient way to gather heat.

That"s a problem of economics. Good solar hot-water systems can harvest much more energy than a solar-electric system at a substantially lower__________（53）. And it"s also a space problem: photovoltaic cells can__________ （54） up all the space on the roof， leaving little room for thermal applications.

In a pair of studies， Joshua Pearce， an associate professor of materials science and engineering，has devised a__________ （55） in the form. of a better PVT made with a different kind of silicon.

His research collaborators are Kunal Girotra from Thin Silicon in California and Michael Pathak and Stephen Harrison from Queen"s University， Canada.

Most solar panels are made with crystalline silicon， but you can also make solar cells out of amorphous silicon， commonly known__________ （56） thin-film silicon. They don"t create as much electricity， but they are lighter， flexible， and cheaper. And， because they__________ （57） much less silicon， they have a greener footprint. __________ （58）， thin-film silicon solar cells are vulnerable to some bad-news physics in the form. of the Staebler-Wronski effect.

"That means that their efficiency drops when you __________（59） them to light——pretty much the worst possible effect for a solar cell，" Pearce explains， which is one of the__________ （60） thin-film solar panels make up only a small fraction of the market.

However， Pearce and his team found a __________（61） to engineer around the Staebler-Wronski effect by incorporating thin-film silicon in a new __________（62） of PVT. You don"t have to cool down thin-film silicon to make it work. In fact， Pearce"s group discovered that by heating it to solar-thermal operating temperatures， near the boiling__________ （63） of water， they could make thicker cells that largely __________（64） the Staebler-Wronski effect. When they applied the thin-film silicon directly to a solar thermal energy collector， they also found that by baking the cell once a day， they__________ （65） the solar cell"s electrical efficiency by over 10 percent.

回答（51）题查看材料

A.until

B.unless

C.when

D.if

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第5题

根据以下材料，回答题DNA FingerprintingDNA is the genetic material found within the cell nuc

根据以下材料，回答题

DNA Fingerprinting

DNA is the genetic material found within the cell nuclei of all living things. In mammals the strands of DNA are grouped into structures called chromosomes. With the exception of identical siblings （as in identical twins）， the complete DNA of each individual is unique.

DNA fingerprinting is sometimes called DNA typing. It is a method of identification that compares bits of DNA. A DAN fingerprint is constructed by first drawing out a DNA sample front body tissue or fluid such as hair， blood， or saliva. The sample is then segmented using enzymes，and the segments are arranged by size. The segments are marked with probes and exposed on X-ray film， where they form. a pattern of black bars- the DNA fingerprint. If the DNA fingerprints produced from two different samples match， the two samples probably came from the same person.

DNA fingerprinting was first developed as an identification technique in 1985. Originally used to detect the presence of genetic diseases， it soon came to be used in criminal investigations and legal affairs. The first criminal conviction based on DNA evidence in the United States occurred in 1988. In criminal investigations， DNA fingerprints derived from evidence collected at the crime scene are compared to the DNA fingerprints of suspects. Generally， courts have accepted the reliability of DNA testing and admitted DNA test results into evidence. However， DNA fingerprinting is controversial in a number of areas: the accuracy of the results， the cost of testing，and the possible misuse of the technique.

The accuracy of DNA fingerprinting has been challenged for several reasons. First， because DNA segments rather than complete DNA strands are "fingerprinted" ; a DNA fingerprint may not be unique; large-scale research to confirn the uniqueness of DNA fingerprinting test results has not been conducted. In addition， DNA fingerprinting is often done in private laboratories that may not follow uniform. testing standards and quality controls. Also， since human beings must interpret the test， human error could lead to false results.

DNA fingerprinting is expensive. Suspects who are unable to provide their own DNA to experts may not be able to successfully defend themselves against charges based on DNA evidence.

Widespread use of DNA testing for identification purposes may lead to the establishment of a DNA fingerprint database.

If two sisters are identical twins， their complete DNAs are __________. 查看材料

A.the same

B.unique

C.different

D.similar

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第6题

Stem cell therapy seems to have great prospects. 查看材

料

A.Right

B.Wrong

C.Not mentioned

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第7题

根据听力，回答题：

A.Most people carl bear the losing of their wallets but not cell phones．

B.Most people admit mobile phones are the“remote control”for life．

C.Most people must live with their mobile phones．

D.Most people owned more than one mobile phone．

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第8题

根据以下材料，回答题Sea HorsesSea horses are unusual parents. The female sea horses lay the

根据以下材料，回答题

Sea Horses

Sea horses are unusual parents. The female sea horses lay the eggs， but unlike other creatures，it"s the males that give birth to the young.

Male sea horses have a fold of skin on their bellies that forms pocket， called a brood pouch.

During the breeding season， the sea horse"s pouch swells to receive eggs. A female sea horse lays up to 200 eggs at a time in the pouch. Then she swims off， leaving her male partner to care for the developing eggs and give birth to young sea horses. The female will return everyday to check on her mate and the eggs， but she doesn"t stay long， nor does she take part in the birth.

It takes from two to six weeks for the eggs in the male"s pouch to develop. During this time the male avoids open water and hides in sea grass. His big pouch makes it difficult for him to swim， so the male often uses his tail to grasp a piece of sea grass. Firmly gripping the grass， he will stay perfectly still for hours or even days. The male sea horse will change his color to blend with his surroundings and avoid being seen by predators who will try to eat him or poke holes in his pouch to get the eggs.

The eggs hatch inside the male"s pouch. When the babies begin moving around， the male sea horse knows it"s time for them to be born. He grabs a sea grass stem with his tail and begins rocking， bending， and stretching his body so that the rest of the babies can be born. Sometimes he has to press his pouch against a rock or some stiff seaweed to force the young out.

Sea horse babies are bom in groups of five or more. Sometimes it takes two days for the father sea horse to give birth to all his young. He is very tired when it"s over.

Soon after giving birth to one brood， the male will approach his mate and show her his empty pouch. This tells her he is ready to receive eggs again.

What part does the female sea horse play in having babies？查看材料

A.Receiving eggs.

B.Laying eggs.

C.Hatching eggs.

D.Protecting eggs.

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第9题

根据以下材料，回答题More about Alzheimer"s DiseaseScientists have developed skin tests that

根据以下材料，回答题

More about Alzheimer"s Disease

Scientists have developed skin tests that may be used in the future to identify people with Alzheimer"s diseasel and may ultimately allow physicians to predict 51_______ is at risk of getting this neurological disorder.

The only current means of 52_______ the disease in a living patient is a long and expensive series of tests that eliminate every other cause of dementia.

"Since Alois Alzheimer described the 53_______ nearly a century .ago， people have been trying to find a way to 54_______ diagnose it in its early stages， " said Patricia Grady， acting director of the National Institute of Neurological Disorders and Stroke in Bethesda， Maryland. "This discovery， if 55_______ ， could prove a big step forward in our efforts to deal with and understand the disease. "

Alzheimer"s is the single greatest 56_______ of mental deterioration in older people， affecting between 2.5 million and 4 million people in the United States 57_______. The devastating disorder gradually destroys memory and the ability to function， and eventually causes death. There is currently no known 58_______ for the disease.

Researches 59_______ that the skin cells of Alzheimer"s patients have defects that interfere with their ability to regulate the flow of potassium in and out of the cells. The fact that the cell defects are present in the skin suggests that Alzheimer"s 60_______ from physiological changes throughout the body， and that dementia may be the first noticeable 61_______ of these changes as the defects affect the cells in the brain， scientists said.

The flow of potassium is especially critical in cells responsible for memory formation. The scientists also found two other defects that affect the cells" supply of calcium， another 62_______ element.

One test developed by researches calls 63_______ growing skin cells in a laboratory culture and then testing them with an electrical detector to determine if the microscopic tunnels that 64_______ the flow of potassium are open. Open potassium channels create a unique electrical signature.

A spokesman for the Alzheimer"s Association said that if the validity of the diagnostic test can be proven it would be an important 65_______， but cautioned that other promising tests for Aizheimer"s have been disappointing.

回答（51）题查看材料

A.what

B.one

C.it

D.who

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第10题

根据以下材料，回答题Electric BackpackBackpacks are convenient. They can hold your books， yo

根据以下材料，回答题

Electric Backpack

Backpacks are convenient. They can hold your books， your lunch， and a change of clothes leaving your hands free to do other things. Someday， if you don"t mind carrying a heavy load， your backpacks might also power your MP3 player， keep your cell phone running， and maybe even light your way home.

Lawrence C. Rome and his colleagues from the University of Pennsylvania in Philadelphia and the Marine Biological Laboratory in Woods Hole， Mass. have invented a backpack thatmakes electricity from energy produced while its wearer walks. In military actions search-and-rescue operations and scientific field studies， people rely increasingly on cellphones global positioning system （GPS） receivers，night-vision goggles， and other battery powered devices to get around and do their work. The backpack"s electricity-generating feature could dramatically reduce the amount of a wearer"s load now devoted to spare batteries， report Rome and his colleagues in the Sept.9 science.

The backpack"s electricity-creating powers depend on springs used to hang a cloth pack from its metal frame. The frame. sits against the wearer"s back， and the whole pack moves up and down as the person walks. A gear mechanism converts vertical movements of the pack to rotary motions of an electrical generator， producing up to 7.4 watts.

Unexpectedly， tests showed that wearers of the new backpack alter their gaits in response to the pack"s oscillations， so that they carry loads more comfortably and with less effort than they do ordinary backpacks. Because of that surprising advantage， Rome plans to commercialize both electric and non-electric versions of the backpack.

The backpack could be especially useful for soldiers， scientists， mountaineers， and emergency workers who typically carry heavy backpacks. For the rest of us， power-generating backpacks could make it possible to walk， play video games， watch TV， and listen to music， all at the same time. Electricity-generating packs aren"t on the market yet， but if you do get one eventually just make sure to look both ways before crossing the street!

Backpacks are convenient because __________. 查看材料

A.they can be verylarge

B.they can hold as many things as you want to carry

C.your handsare freed to do other things

D.you do not have to carry things withyou

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根据以下材料，回答题Stem Cell Therapy May Help Repair the HeartAccording to scientists in t