词汇选项
The doctors have abandoned the hope to rescue the old man.
A.left
B.given up
C.turned down
D.refused
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Medical Journals
Medical journals are publications that report medical information to physicians and other health professionals.
In the past, these journals were available only in print. With the development of electronic publishing, many medical journals now have Web sites on the Internet, and some journals are published only online. A few medical journals, like the Journal of the American Medical Association, are considered general medical journals because they cover many fields of medicine. Most medical journals are specialty journals that focus on a particular area of medicine.
Medical journals publish many types of articles. Research articles report the results of research studies on a range of topics varying from the basic mechanisms of diseases to clinical trials that compare outcomes of different treatments. Review articles summarize and analyze the information available on a specific topic based on a careful search of the medical literature. Because the results of individual research studies can be affected by many factors, combining results from different studies on the same topic can be helpful in reaching conclusions about the scientific evidence for preventing, diagnosing or treating a particular disease. Case conferences and case reports may be published in medical journals to educate physicians about particular illnesses and how to treat them. Editorials in medical journals are short essays that express the views of the authors, often regarding a research or review article published in the same issue. Editorials provide a perspective on how the current article fits with other information on the same topic. Letters to the editor provide a way for readers of the medical journal to express comments, questions or criticisms about articles published in that journal.
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Sleep
Sleep is part of a person’s daily activity cycle. There are several different stages of sleep, and they too occur in cycles.【B1】______When you first drift off into slumber, your eyes will roll about a bit, your temperature will drop slighdy, your muscles will relax, and your breathing will slow and become quite regular. Your brain waves slow down a bit too, with the alpha rhythm of rather fast waves predominating for the first few minutes.【B2】______For the next half hour or so, as you relax more and more, you will drift down through stage 2 and stage 3 sleep. 【B3】______Then about 40 to 60 minutes after you lose consciousness you will have reached the deepest sleep of all. Your brain waves will show the large slow waves that are known as the delta rhythm. This is stage 4 sleep. You do not remain at this deep fourth stage all night long, but instead about 80 minutes after you fall into slumber, your brain activity level will increase again slightly. 【B4】______Your eyes will begin to dart around under your closed eyelids as if you were looking at something occurring in front of you.【B5】______It is during REM sleep period, your body will soon relax again, your breathing will grow slow and regular once more, and you will slip gently back from stage 1 to stage 4 sleep-only to rise once again to the surface of near consciousness some 80 minutes later.
A The delta rhythm will disappear, to be replaced by the activity pattern of brain waves.
B If you are an average sleeper, your sleep cycle is as follows.
C In stage 4 sleep people tend to dream.
D The lower your stage of sleep, the slower your brain waves will be.
E This period of rapid eye movement lasts for some 8 to 15 minutes and is called REM sleep.
F This is called stage 1 sleep.
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Hair Care
Whether the hair is long or short, it must be regularly brushed and regularly washed. For greasy(油性的)hair, especially if the owner lives in a town, it may be necessary to wash the head every four to five days. Those with a dry hair can usually go a little longer, but this is a matter for the individual to decide.
As for style, this must be studied according to what is the latest fashion and also to suit the individual at different times of her life. If a woman is not able to go to hairdresser very often, it is important that she chooses a style she can easily manage for herself, and this nearly always means that the first cut must be very standard. The same applies to permanent waving(烫发). I think that this should be carried out three or four times a year, so that the hair never gets out of hand.
One thing would be remembered though, that is, whatever you apply to the head can have some effect upon the skin and therefore anything strong should be used with care. Or you may use milder products.
Young people who has spots or skin troubles on their face should take particular care to ensure that the hair is both clean and does not come into contact with the affected piece of skin. Hair is very difficult to keep completely clean and therefore anyone running their hands through their hair and afterwards touching their face, or letting their hair fall over their faces, might spread infection from one place to another.
Good hair does a lot to the effect of a face, so if you want to look charming, please start with your hair.
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Clone Farm
Factory farming could soon enter a new era of mass production. Companies in the US are developing the technology needed to“ clone“chickens on a massive scale. Once a chicken with desirable traits has been bred or genetically engineered, tens of thousands of eggs, which will hatch into identical copies, could roll off the production lines every hour. Billions of clones could be produced each year to supply chicken farms with birds that all grow at the same rate, have the same amount of meat and taste the same.
This, at least, is the vision of the US’s National Institute of Science and Technology, which has given Origen Therapeutics of Burlingame, California, and Embrex of North Carolina $ 4. 7 million to help fund research. The prospect has alarmed animal welfare groups, who fear it could increase the suffering of farm birds.
That’s unlikely to put off the poultry industry, however, which wants disease-resistant birds that grow faster on less food. “ Producers would like the same meat quantity but to use reduced inputs to get there, “says Mike Fitzgerald of Origen. To meet this demand, Origen aims to“create an animal that is effectively a clone“ , he says. Normal cloning doesn’t work in birds because eggs can’t be removed and implanted. Instead, the company is trying to bulk-grow embryonic stem cells taken from fertilized eggs as soon as they’re laid. “The trick is to culture the cells without them starting to distinguish, so they remain pluripotent, “ says Fitzgerald.
Using a long-established technique, these donor cells will then be injected into the embryo of a freshly laid, fertilized recipient egg, forming a chick that is a“chimera“. Strictly speaking a chimera isn’t a clone, because it contains cells from both donor and recipient. But Fitzgerald says it will be enough if, say, 95 percent of a chicken’s body develops from donor cells. “In the poultry world, it doesn’t matter if it’s not 100 percent, “he says.
Another challenge for Origen is to scale up production. To do this, it has teamed up with Embrex, which produces machines that can inject vaccines into up to 50, 000 eggs an hour. Embrex is now trying to modify the machines to locate the embryo and inject the cells into precisely the right spot without killing it.
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First Self-contained Heart Implanted
A patient on the brink of death has received the world’s first self-contained artificial heart— a battery-powered device about the size of a softball that runs without the need for wires, tubes or hoses sticking out of the chest.
Two surgeons from the University of Louisville implanted the titanium and plastic pump during a seven-hour operation at Jewish Hospital Monday. The hospital said the patient was“ awake and responsive“ Tuesday and resting comfortably. It refused to release personal details.
The patient had been expected to die within a month without the operation, and doctors said they expected the artificial heart to extend the person’s life by only a month. But the device is considered a major step toward improving the patient’s quality of life.
The new pump, called AbioCor, is also a technological leap from the mechanical hearts used in the 1980s, which were attached by wires and tubes to bulky machinery outside the body. The most famous of those, the Jarvic-7, used air as a pumping device and was attached to an apparatus about the size of a washing machine.
“ I think it’s potentially a major step forward in the artificial heart development, “ said Dr. David Faxon, president of the American Heart Association. However, he said the dream of an implantable , permanent artificial heart is not yet a reality, “ This is obviously an experimental device whose long-term success has to be demonstrated. “ Only about half of the 4, 200 Americans on a waiting list for donor hearts received them last year, and most of the rest died.
Some doctors, including Robert Higgins, chairman of cardiology at the Medical College of Virginia in Richmond, said artificial hearts are unlikely to replace donor hearts.
“A donor heart in a good transplant can last 15 to 30 years, “ he said. “It’s going to be hard to replace that with a machine. “
The AbilCor has a 2-pound pumping unit, and electronic controls that adjust the pumping speed based on the body’s needs. It is powered by a small battery pack worn outside the body that transmits current through the skin.