首页
登录
职称英语
An American survey has shown that each year every employed person loses thre
An American survey has shown that each year every employed person loses thre
游客
2023-12-10
24
管理
问题
An American survey has shown that each year every employed person loses three to four working days from colds and allied complaints, and every school child loses five to six days of schooling. Colds waste more time than strikes. The conquest of the common cold is therefore a thoroughly worthwhile ambition.
In 1961, Sir Christopher Andrewes found that the great killing infections like syphilis or poliomyelitis are each caused by one specific micro-organism, or, at worst, a small group of closely related parasites. By contrast it has slowly become apparent that the common cold is not a disease but a large group of similar diseases, caused possibly, by anything between fifty and one hundred different organisms.
Much of Sir Christopher’s book is taken up by an account of the struggle to identify, the germs which do cause colds. At first it was thought that bacteria were responsible because certain bacteria are commonly found in the noses and throats of cold victims. But Dr. W. Kruse of the Hygienic Institute of the University of Leipzig in 1914 provided the first evidence that a virus might be concerned by launching experimental infections.
Since that time thousands of volunteers have subjected themselves to similar experimental infections, and for early twenty years most of such work has been done at Salisbury where the guinea pigs are rewarded by a ten-day holiday, all found that this "clumsy, expensive and unreliable" use of human volunteers was necessary because for a long time chimpanzees were the only other animals known to be susceptible to infection by common cold germs, and chimpanzees were far too expensive and unruly for routine use.
Growing cold viruses in the laboratory also proved difficult until one of the men involved demonstrated his possession of that most precious scientific faculty-serendipity.
Cold viruses were being grown with only moderate success in laboratory cultures of lung tissue from human embryos. The lung tissue cultures were kept alive by a salt solution containing added vitamins and a number of other ingredients. One day at Salisbury Dr. David Tyrrell found that this salt solution was faulty, and in order to keep his tissue cultures going he hastily borrowed a supply from another laboratory. When the imported solution was added to tissue cultures infected with cold viruses the lung tissue cells began to degenerate in a manner typical of tissues parasitized by active viral particles.
Dr. Tyrrell soon discovered that the borrowed fluid provided a more acid medium in his culture tubes than that produced by the native Salisbury brew. The nose provides a slightly acid environment, and Dr. Tyrrell realized that a degree of acidity was just what nose-inhabiting viruses needed in order to thrive outside the body. Thus a happy accident enabled a perspicacious scientist to modify the cold virus culture technique and thenceforward the whole exercise proved far easier and more profitable.
Much of common cold folklore is demolished. Draughts, chilling and wet feet do not bring colds on, says Sir Christopher, and clean, healthy living with lots of fresh air, plenty of exercise, good, plain food and a cold bath every morning may be good for the soul and the waistline, but does nothing to keep cold viruses at bay.
Colds are not very infectious — which will surprise most of us — so there is really no excuse for staying away from work when you have one. All the remedies so far invented have one thing in common — they are useless. In temperate countries, colds are commoner during the winter, but what the "winter factor" is which brings them on remains unknown. Most of us harbour cold viruses in our noses throughout the year, and many colds are probably not "caught" at all, but start because somehow the resident viruses become activated from time to time.
To write a book about colds at this stage, says Sir Christopher, is rather like writing a review of a play in the middle of the first act. Since he wrote those words, workers at Salisbury have announced the production of the first cold vaccine which will protect against infection by one particular cold virus. Unfortunately there are very many cold viruses and complete immunity from colds by vaccination would require the administration of a separate vaccine for every virus in the book. [br] The phrase "a happy accident" in Paragraph Seven means that Dr. Tyrrell’s discovery was
选项
A、likely to add to human happiness.
B、beneficial and unforeseen.
C、lucky and due to coincidence.
D、due to an expected event.
答案
B
解析
词义理解题。a happy accident指的是Dr.Tyrrell因实验室内的盐溶液出了问题,而意外发现了感冒菌需在一定浓度的酸性溶液中培养这件事,因而改进感冒细菌的培养技术,使整个操作更为便捷,故这是“有益的”,而这件事属于一次意外收获,故是“未预见的”,因此B为正确答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3261682.html
相关试题推荐
ThefollowingwerethefoundingfathersoftheAmericanRepublicEXCEPT______.A、
WhichbranchoftheAmericangovernmenthasthepowertointerprettheConstitut
Ithadoccurredtoherearlythatinherposition—thatofayoungpersonspe
Ithadoccurredtoherearlythatinherposition—thatofayoungpersonspe
Ithadoccurredtoherearlythatinherposition—thatofayoungpersonspe
Justas【1】______isfamousforthetango,soAmerican【1】______iswell-known
Justas【1】______isfamousforthetango,soAmerican【1】______iswell-known
Justas【1】______isfamousforthetango,soAmerican【1】______iswell-known
Justas【1】______isfamousforthetango,soAmerican【1】______iswell-known
Justas【1】______isfamousforthetango,soAmerican【1】______iswell-known
随机试题
[originaltext]W:Isthisthebusthatgoesbythemall?M:No,itisn’t.Butyo
ThankyouforyourletterofAugust31,2012andenclosedresume.Asadv
TheUnitedStates’predominanceinscienceandtechnologyisfading,arepor
用n表示检测次数,S表示标准偏差、x表示平均值,则变异系数Cv为()。A.s/
贷款公司是专门为县域农民、农业和农村经济发展提供贷款服务的非银行金融机构。(
某企业购入甲原材料和乙原材料均已验收入库,尚未支付货款。其中甲原材料的实际采购成
平面汇交力系的力多边形如图所示,该力系的合力等于:
(2013年)根据环境影响评价技术导则—声环境,计算室内声源的室外等效声源的声功
在疏浚工程施工组织设计编制中,应根据影响本工程施工的自然因素,确定本工程挖泥船的
根据《危险化学品安全管理条例》,关于危险化学品运输安全的说法,正确的是( )。
最新回复
(
0
)