剑桥雅思系列真题是剑桥大学考试委员会外语考试部出版各类考试真题的唯一官方出版社出版的权威教材，书中包含最新的雅思全真试题资料，是各类雅思考生备考过程中必不可少的参考书。非常适合学生自学的习题解答和听力录音文本。
PASSAGE 1 参考译文：
A The Lumiere Brothers opened their Cinematographe, at 14 Boulevard des Capucines in Paris, to 100 paying customers over 100 years ago, on December 8, 1895. Before the eyes of the stunned, thrilled audience, photographs came to life and moved across a flat screen.
A 一百多年前，在1895年12月8日，吕米埃兄弟在巴黎嘉布欣大道14号向100名买票人场的观众放映了他们制作的电影。在目瞪口呆、惊恐颤抖的观众面前，一张张照片活动起来并在平面的银幕上穿梭而过。
B So ordinary and routine has this become to us that it takes a determined leap of the imagination to grasp the impact of those first moving images. But it is worth trying, for to understand the initial shock of those images is to understand the extraordinary power and magic of cinema, the unique, hypnotic quality that has made film the most dynamic, effective art form of the 20th century.
B 看电影对于我们来说是司空见惯的事，所以要理解这些活动的画面最初产生的影响，想象力非得来次巨大的飞跃不可。然而这值得一试，因为理解了这些影像最初带来的震撼，就可以理解电影非同寻常的力量和魔力，理解为什么电影具有独特而迷人的品质。正是这种品质，使电影成为20世纪最具有活力和感染力的艺术形式。
C One of the Lumiere Brothers’ earliest films was a 30-second piece which showed a section of a railway platform flooded with sunshine. A train appears and heads straight for the camera. And that is all that happens. Yet the Russian director Andrei Tarkovsky, one of the greatest of all film artists, described the film as a ‘work of genius’. ‘As the train approached,’ wrote Tarkovsky, ‘panic started in the theatre: people jumped and ran away. That was the moment when cinema was born. The frightened audience could not accept that they were watching a mere picture. Pictures were still, only reality moved; this must, therefore, be reality. In their confusion, they feared that a real train was about to crush them.’
C 吕米埃兄弟的早期电影作品之一是一部30秒长的短片，表现了一段沐浴在阳光下的火车月台的场景。一辆火车出现了，并且直冲镜头开来。这就是电影的全部。然而，杰出的电影艺术家俄罗斯导演安德列·塔科夫斯基却称其为“天才之作”。他写道：“随着火车不断驶近，影院里呈现出一片慌恐的景象：人们跳离座位，四散而逃。就在这一刻，电影宣告诞生。恐惧的观众无法相信他们看到的仅仅是一幅图画。图画是静止的，只有现实中的事物才会运动;因此，这一定是现实。在疑惑迷茫之中，观众担心一列真正的火车将会把他们轧得粉身碎骨。”
D Early cinema audiences often experienced the same confusion. In time, the idea of film became familiar, the magic was accepted — but it never stopped being magic. Film has never lost its unique power to embrace its audiences and transport them to a different world. For Tarkovsky, the key to that magic was the way in which cinema created a dynamic image of the real flow of events. A still picture could only imply the existence of time, while time in a novel passed at the whim of the reader. But in cinema, the real, objective flow of time was captured.
D 早期的电影观众们经常会有同样的迷茫。随着时间的推移，电影这一概念为人们所熟知，电影的魔力也广为人们接受，但电影的魔力并没有因此而消失。电影不断地以其独特的力量去感染观众并将他们带人一个不同寻常的世界。对塔科夫斯基而言，魔力的关键在于电影所创造的表现方式是以动态的影像来反映真实事件的进展。静止的图画仅仅暗示了时间的存在，而小说中的时间则在读者的幻想中不断延伸。然而， 电影却捕捉了真实而客观的时间流动。
E One effect of this realism was to educate the world about itself. For cinema makes the world smaller. Long before people travelled to America or anywhere else, they knew what other places looked like; they knew how other people worked and lived. Overwhelmingly, the lives recorded — at least in film fiction — have been American. From the earliest days of the industry, Hollywood has dominated the world film market. American imagery — the cars, the cities, the cowboys — became the primary imagery of film. Film carried American life and values around the globe.
E 这种现实性的作用之一是使世界去了解自身。因为电影将世界缩小。早在人们到美国或其他地方旅行之前，他们就已经欣赏过目的地的风光，也领略过当地人的工作与生活方式。至少在虚构的电影世界中，记录的绝大多数是美国人的生活。从电影业发展初期至今，好莱坞一直占据着世界电影市场的统治地位。汽车、城市和牛仔这些美国形象已经成为电影中的主要形象。电影将美国人的生活方式和价值观念传播到了全世界。
F And, thanks to film, future generations will know the 20th century more intimately than any other period. We can only imagine what life was like in the 14th century or in classical Greece. But the life of the modern world has been recorded on film in massive, encyclopedic detail. We shall be known better than any preceding generations.
F同时，正是由于电影的帮助，相对于其他时代，我们的后代将对20世纪了解得更为清楚。对于14世纪或者古希腊的生活状况，我们只能想象。但现代世界的生活方式已经被电影事无巨细地大量记录下来。后人对我们这一代的了解将会比对任何前人的了解更加透彻。
G The ‘star’ was another natural consequence of cinema. The cinema star was effectively born in 1910. Film personalities have such an immediate presence that, inevitably, they become super-real. Because we watch them so closely and because everybody in the world seems to know who they are, they appear more real to us than we do ourselves. The star as magnified human self is one of cinema’s most strange and enduring legacies.
G“影星”是电影带来的另一个产物。实际上，影星这一概念出现于1910年。电影人物触手可及，这使他们必然显得无比真实。对于我们而言，影星们似乎比我们自身更为真实，因此我们可以如此近距离地观察他们，而县好像世界上的每个人都认识他们。作为人类自身的放大，影星是电影留下的最不可思议而又最持久的影响。
H Cinema has also given a new lease of life to the idea of the story. When the Lumiere Brothers and other pioneers began showing off this new invention, it was by no means obvious how it would be used. All that mattered at first was the wonder of movement. Indeed, some said that, once this novelty had worn off, cinema would fade away. It was no more than a passing gimmick, a fairground attraction.
H 电影也赋予小说故事新的生命。当吕米埃兄弟和其他先驱者初次展示电影这项新发明时，他们根本不淸楚该怎样应用它。最初重要的只是影像能活动。的确，有些人就断言，一旦新奇感消失，电影就会逐渐淡出人们的视线。它只不过是一种暂时流行的小玩意儿，或是露天市场上的“杂耍”而已。
I Cinema might, for example, have become primarily a documentary form. Or it might have developed like television — as a strange, noisy transfer of music, information and narrative. But what happened was that it became, overwhelmingly, a medium for telling stories. Originally these were conceived as short stories — early producers doubted the ability of audiences to concentrate for more than the length of a reel. Then, in 1912, an Italian 2-hour film was hugely successful, and Hollywood settled upon the novel-length narrative that remains the dominant cinematic convention of today.
I 例如，电影原本可能变成一种以纪录片为主的形式，或者可能像电视那样发展，成为传输音乐、信息和故事的怪异而喧闹的工具。然而，事实是，电影已经成为一种叙事的主要媒介。最初讲述的都是短小的故事，因为早期制作者们怀疑观众顶多只能集中精力去看完一卷胶片。后来，一部长达两个小时的意大利电影在1912年获得了巨大的成功，从此好莱坞电影就开始采用这种新的叙事长度。至今，这一形式依然在电影界保持着惯例式的统治地位。
J And it has all happened so quickly. Almost unbelievably, it is a mere 100 years since that train arrived and the audience screamed and fled, convinced by the dangerous reality of what they saw, and, perhaps, suddenly aware that the world could never be the same again — that, maybe, it could be better, brighter, more astonishing, more real than reality.
J 而这一切都发生得如此迅速。令人几乎难以置信的是，距离那辆火车到站时，观众们认为所看到的是危险的现实而尖叫不止、四散奔逃的景象，只不过一百年的时间。或许，人们意识到世界已经发生了彻底的改变，而且可能会变得比现实更加美好、光明、惊人和真实。
TEST 3 PASSAGE 2 参考译文：
Motivating Employees under Adverse Conditions
在逆境中激励员工挑战
THE CHALLENGE
It is a great deal easier to motivate employees in a growing organisation than a declining one. When organisations are expanding and adding personnel, promotional opportunities, pay rises, and the excitement of being associated with a dynamic organisation create feelings of optimism. Management is able to use the growth to entice and encourage employees. When an organisation is shrinking, the best and most mobile workers are prone to leave voluntarily. Unfortunately, they are the ones the organisation can least afford to lose — those with the highest skills and experience. The minor employees remain because their job options are limited.
挑战
在不断壮大的企业中激励员工要比在日益衰落的企业中容易得多。当企业扩大经营和增加员工人数时，晋升机会增多，薪酬提高，而且加人一家充满活力的企业所带来的振奋感也会产生乐观向上的情绪。 管理层能够利用企业的发展来吸引和鼓舞员工。当企业衰退时，流动性最强的优秀员工就会主动离开。不幸的是，这些才能出众、经验丰富的员工正是企业最不能失去的人才。表现平庸的员工坚持留下，因为可供他们选择的职位有限。
Morale also suffers during decline. People fear they may be the next to be made redundant. Productivity often suffers, as employees spend their time sharing rumours and providing one another with moral support rather than focusing on their jobs. For those whose jobs are secure, pay increases are rarely possible. Pay cuts, unheard of during times of growth, may even be imposed. The challenge to management is how to motivate employees under such retrenchment conditions. The ways of meeting this challenge can be broadly divided into six Key Points, which are outlined below.
员工的士气在企业衰退期也会下降。人们担心自己或许就是下一个被解雇的人。生产率通常有所下降，因为员工宁愿将时间花费在传播谣言和相互提供精神支持上，也不愿意专注于工作。对工作稳定的人而言，加薪几乎是不可能的。在企业发展时期闻所未闻的减薪，此时甚至也会强制实施。管理层所面对的挑战是如何在企业衰退期激励员工。迎接这一挑战的方法可以大致分为下列六个关键点。
KEY POINT ONE
There is an abundance of evidence to support the motivational benefits that result from carefully matching people to jobs. For example, if the job is running a small business or an autonomous unit within a larger business, high achievers should be sought. However, if the job to be filled is a managerial post in a large bureaucratic organisation, a candidate who has a high need for power and a low need for affiliation should be selected. Accordingly, high achievers should not be put into jobs that are inconsistent with their needs. High achievers will do best when the job provides moderately challenging goals and where there is independence and feedback. However, it should be remembered that not everybody is motivated by jobs that are high in independence, variety and responsibility.
关键点一
大量证据表明，切实做到人尽其才能够激发工作动力。例如，小型企业或大型企业中自主单位的经营者，应当由业绩杰出者担任。但是，如果空缺的是大型官僚机构的管理职位，则应当选择对权力需求髙而对关系需求低的人选。相应地，不能为业绩杰出者安排与其需求不一致的工作。只有当职位能够提供具有一定挑战性的目标，具有独立性，并提供反馈时，他们才会全力以赴地工作。然而，我们应当牢记并不是每个人都会被独立性强、形式多样和责任要求高的工作所激励。
KEY POINT TWO
The literature on goal-setting theory suggests that managers should ensure that all employees have specific goals and receive comments on how well they are doing in those goals. For those with high achievement needs, typically a minority in any organisation, the existence of external goals is less important because high achievers are already internally motivated. The next factor to be determined is whether the goals should be assigned by a manager or collectively set in conjunction with the employees. The answer to that depends on perceptions of goal acceptance and the organisation’s culture. If resistance to goals is expected, the use of participation in goal-setting should increase acceptance. If participation is inconsistent with the culture, however, goals should be assigned. If participation and the culture are incongruous, employees are likely to perceive the participation process as manipulative and be negatively affected by it.
关键点二
目标设定理论的相关文献提出，管理者们必须确保所有的员工都有明确的目标并且能够在实现该目标的过程中获得评价。追求卓越成就的人是所有企业中具有代表性的少数群体，对于他们而言，外部目标的存在并不十分重要，因为业绩杰出者已具有极强的内在动机。下一个要决定的因素是目标应由管理者指定，还是应由全体员工共同设定。答案取决于人们对目标的接受程度和企业文化。如果有可能出现对目标的抵制，在设定S标时鼓励员工参与就会提高接受的程度。然而，如果这种参与和企业文化相矛盾，则应当指定目标。如果参与和企业文化不一致，员工则有可能认为自己在参与过程中被操纵，并且受到负面影响。
KEY POINT THREE
Regardless of whether goals are achievable or well within management’s perceptions of the employee’s ability, if employees see them as unachievable they will reduce their effort. Managers must be sure, therefore, that employees feel confident that their efforts can lead to performance goals. For managers, this means that employees must have the capability of doing the job and must regard the appraisal process as valid.
关键点三
无论目标是否能够实现，也无论目标是否在管理层认定的员工能力范围之内，只要员工们认为无法实现目标，他们就不会那么努力。因此，管理者必须确保员工相信他们的努力会使绩效目标实现。对于管理者而言，这意味着员工必须能够胜任工作，而且必须承认(绩效)评估流程的有效性。
KEY POINT FOUR
Since employees have different needs, what acts as a reinforcement for one may not for another. Managers could use their knowledge of each employee to personalise the rewards over which they have control. Some of the more obvious rewards that managers allocate include pay, promotions, autonomy, job scope and depth, and the opportunity to participate in goal-setting and decision-making.
关键点四
由于员工们有不同的需求，所以对一个人产生强化效果的事物对于另一个人而言未必适用。在其控制范围内，管理者可以根据对不同员工的了解给予他们相应的奖励。管理者们可给予员工的奖励主要包括薪酬、晋升、自主权、业务范围和深度，以及参与目标设定和决策的机会。
KEY POINT FIVE
Managers need to make rewards contingent on performance. To reward factors other than performance will only reinforce those other factors. Key rewards such as pay increases and promotions or advancements should be allocated for the attainment of the employee’s specific goals. Consistent with maximising the impact of rewards, managers should look for ways to increase their visibility. Eliminating the secrecy surrounding pay by openly communicating everyone’s remuneration, publicising performance bonuses and allocating annual salary increases in a lump sum rather than spreading them out over an entire year are examples of actions that will make rewards more visible and potentially more motivating.
关键点五
管理者需要将奖励与绩效挂钩。除工作表现之外，对于其他方面的奖励只会使这些方面得到加强。诸如加薪和晋升这样的主要奖励应在员工实现特定目标后给予。与最大化奖励效果相一致，管理者应当设法增加奖励的公开性。例如，通过公示员工工资数目来消除薪酬的保密状态;公布绩效奖金数额;一次性支付年薪的增加额，而不是将其在全年中分别发放;这些方法可以增加奖励的公开性和潜在激励性。
KEY POINT SIX
The way rewards are distributed should be transparent so that employees perceive that rewards or outcomes are equitable and equal to the inputs given. On a simplistic level, experience, abilities, effort and other obvious inputs should explain differences in pay, responsibility and other obvious outcomes. The problem, however, is complicated by the existence of dozens of inputs and outcomes and by the fact that employee groups place different degrees of importance on them. For instance, a study comparing clerical and production workers identified nearly twenty inputs and outcomes. The clerical workers considered factors such as quality of work performed and job knowledge near the top of their list, but these were at the bottom of the production workers’ list. Similarly, production workers thought that the most important inputs were intelligence and personal involvement with task accomplishment, two factors that were quite low in the importance ratings of the clerks. There were also important, though less dramatic, differences on the outcome side. For example, production workers rated advancement very highly, whereas clerical workers rated advancement in the lower third of their list. Such findings suggest that one person’s equity is another’s inequity, so an ideal should probably weigh different inputs and outcomes according to employee group.
关键点六
奖励的分配方式必须透明，使员工认识到奖励或成果是公平并且与特定投人相对等的。简而言之，经验、才能，努力及其他主要的投人应当体现在薪酬、职责和其他主要产出的差异方面。然而，问题之所以复杂，不仅是因为投人与产出有多种形式，而且还因为各员工群体对它们的重视程度不同。比如，一项究在比较行政工作人员和生产工人之后，确定了近二十种投人与产出的形式。行政工作人员基本上最重视所做工作的质量和业务知识等因素，但这正是生产工人们最不重视的。同样，生产工人们认为最重要的投人是才智和任务完成过程中的个人参与，而这两个因素在行政工作人员的重要性等级排名中则十分靠后。产出方面也有一些同样重要但不很明显的差异。例如，生产工人认为晋升非常重要，但行政工作人员却将晋升排到了重要性列表中的后三位。上述发现表明，一个人认为是公平的事物对于另一个人而言可能是不公平的。因此，理想的方式或许应当针对不同员工群体权衡不同的投人与产出。
TEST 3 PASSAGE 3 参考译文：
The Search for the Anti-aging Pill
In government laboratories and elsewhere, scientists are seeking a drug able to prolong life and youthful vigor. Studies of caloric restriction are showing the way
寻找抗衰老药
在政府实验室等地，科学家们正在寻找能够延长生命和保持青春活力的药物。有关热量限制的研究为我们指明了出路。
As researchers on aging noted recently, no treatment on the market today has been proved to slow human aging — the build-up of molecular and cellular damage that increases vulnerability to infirmity as we grow older. But one intervention, consumption of a low-calorie*yet nutritionally balanced diet, works incredibly well in a broad range of animals, increasing longevity and prolonging good health. Those findings suggest that caloric restriction could delay aging and increase longevity in humans, too.
衰老问题的研究者们最近指出，目前市面上还没有任何疗法证明可以延缓人类衰老。衰老是一种随着年龄增长，人体内分子与细胞损伤的累积导致人越来越虚弱的现象。然而，有一种干预措施对许多动物都十分有效，那就是低热量且营养均衡的饮食，它会延长实验动物的寿命并维系健康。这些研究结果表明，限制热量的摄取可能也会延缓衰老，延长人类的寿命。
Unfortunately, for maximum benefit, people would probably have to reduce their caloric intake by roughly thirty per cent, equivalent to dropping from 2,500 calories a day to 1,750. Few mortals could stick to that harsh a regimen, especially for years on end. But what if someone could create a pill that mimicked the physiological effects of eating less without actually forcing people to eat less? Could such a ‘caloric-restriction mimetic’, as we call it, enable people to stay healthy longer, postponing age-related disorders (such as diabetes, arteriosclerosis, heart disease and cancer) until very late in life? Scientists first posed this question in the mid-1990s, after researchers came upon a chemical agent that in rodents seemed to reproduce many of caloric restriction’s benefits. No compound that would safely achieve the same feat in people has been found yet, but the search has been informative and has fanned hope that caloric-restriction (CR) mimetics can indeed be developed eventually.
不幸的是，若想达到最佳效果，人们大概需要减少约30%卡路里的摄人量，相当于从每天2500大卡降低到1750大卡。很少有人能够坚持这样严格的养生之道，尤其是年复一年这样做。但能不能制造出一种药来模拟限食的生理效应，而又不需要强迫人们少吃东西呢?这种被我们称为“限食拟药”的药片是否能让人们长久保持健康，延缓老年疾病(比如糖尿病、动脉硬化症、心脏病及癌症)的发生，直到更老的时候?科学家们早在20世纪90年代中期就提出了这个问题，此前研究者们偶然发现了一种化学药剂，该药剂似乎可以在啮齿动物身上产生限制热量摄取的许多好处。至今我们还没有发现能够安全应用到人类身上并达到同样功效的药物，但研究经验助燃了希望之火，令我们相信，限食拟药终究会研制出来的。
The benefits of caloric restriction
The hunt for CR mimetics grew out of a desire to better understand caloric restriction’s many effects on the body. Scientists first recognized the value of the practice more than 60 years ago, when they found that rats fed a low-calorie diet lived longer on average than free-feeding rats and also had a reduced incidence of conditions that become increasingly common in old age. What is more, some of the treated animals survived longer than the oldest-living animals in the control group, which means that the maximum lifespan (the oldest attainable age), not merely the normal lifespan, increased. Various interventions, such as infection-fighting drugs, can increase a population’s average survival time, but only approaches that slow the body’s rate of aging will increase the maximum lifespan.
限制能量摄入的好处
寻找限食拟药的动机是我们想更多地了解限制热量摄取对身体的影响。科学家们早在60多年前就已经认识到限制热量摄人的益处。当时，他们发现被喂食低热量食物的鼠类平均寿命长于自由摄取食物的鼠类，而且也更少患鼠类衰老时的常见病。除此之外，食用低热食物的鼠类活得比对照组中最老的鼠类还要长，这表明不仅是平均寿命，连最大寿命(可活的最大年龄)也增加了。尽管抗感染药物等各种干预方法也可以增加种群的平均寿命，但只有通过降低身体衰老速率才能增加最大寿命。
The rat findings have been replicated many times and extended to creatures ranging from yeast to fruit flies, worms, fish, spiders, mice and hamsters. Until fairly recently, the studies were limited to short-lived creatures genetically distant from humans. But caloric-restriction projects underway in two species more closely related to humans — rhesus and squirrel monkeys — have made scientists optimistic that CR mimetics could help people.
鼠类的实验结果已经重复过多次，而且对酵母菌、果蝇、蠕虫、鱼、蜘蛛、小鼠及仓鼠的实验也都有同样的结果。迄今，这类研究针对的都只是与人类基因相去甚远的短命生物，然而，正在进行中的研究采用了恒河猴与松鼠猴这两种更接近人类的物种做实验对象，这使科学家们乐观地相信限食拟药可以帮助人类。
The monkey projects demonstrate that, compared with control animals that eat normally, caloric-restricted monkeys have lower body temperatures and levels of the pancreatic hormone insulin, and they retain more youthful levels of certain hormones that tend to fall with age.
对这些猴类的研究证实，比起正常饮食的对照组动物，限制热量摄人组猴子的体温和胰岛素浓度都较低，而且某些随年龄增长而降低的荷尔蒙在他们体内仍维持在年轻时的水平。
The caloric-restricted animals also look better on indicators of risk for age-related diseases. For example, they have lower blood pressure and triglyceride levels (signifying a decreased likelihood of heart disease), and they have more normal blood glucose levels (pointing to a reduced risk for diabetes, which is marked by unusually high blood glucose levels). Further, it has recently been shown that rhesus monkeys kept on caloric-restricted diets for an extended time (nearly 15 years) have less chronic disease. They and the other monkeys must be followed still longer, however, to know whether low-calorie intake can increase both average and maximum life spans in monkeys. Unlike the multitude of elixirs being touted as the latest anti-aging cure, CR mimetics would alter fundamental processes that underlie aging. We aim to develop compounds that fool cells into activating maintenance and repair.
在与衰老有关的疾病风险指数方面，这些热量摄人受限的动物看起来也更加健康。例如，它们的血压与甘油三酸酷含量都比较低(表示得心脏病的可能性较小)，血糖浓度也比较正常(表示得糖尿病的风险较低，糖尿病的特征是高于常规的血糖浓度)。此外，有关研究最近指出，长期限制热量摄人(将近15年)的恒河猴患慢性病的几率也较低。但想要知道限制热量摄人是否会延长猴类的平均寿命和最长寿命，我们还必须对这些恒河猴以及其他猴类做更长时间的跟踪研究。与众多被吹捧为最新抗衰老疗法的长生不老药不同，限食拟药会改变衰老的基本进程。我们的目标是研制出能够欺骗细胞进人保养与修复状态的药物。
How a prototype caloric-restriction mimetic works
The best-studied candidate for a caloric-restriction mimetic, 2DG (2-deoxy-D-glucose), works by interfering with the way cells process glucose. It has proved toxic at some doses in animals and so cannot be used in humans. But it has demonstrated that chemicals can replicate the effects of caloric restriction; the trick is finding the right one.
限食拟药如何完成任务
研究得最多、也是最有可能的限食拟药是2DG(2-去氧-D-葡萄糖)，它是通过影响细胞中葡萄糖的代谢过程而发挥作用的。实验发现，达到某一剂量时，2DG会对动物产生毒性，所以无法应用到人类身上。尽管如此，这表明有些化学药物的确可以模拟热量摄人受限的效果;关键在于如何找到合适的药物。
Cells use the glucose from food to generate ATP (adenosine triphosphate), the molecule that powers many activities in the body. By limiting food intake, caloric restriction minimizes the amount of glucose entering cells and decreases ATP generation. When 2DG is administered to animals that eat normally, glucose reaches cells in abundance but the drug prevents most of it from being processed and thus reduces ATP synthesis. Researchers have proposed several explanations for why interruption of glucose processing and ATP production might retard aging. One possibility relates to the ATP-making machinery’s emission of free radicals, which are thought to contribute to aging and to such age-related diseases as cancer by damaging cells. Reduced operation of the machinery should limit their production and thereby constrain the damage. Another hypothesis suggests that decreased processing of glucose could indicate to cells that food is scarce (even if it isn’t) and induce them to shift into an anti-aging mode that emphasizes preservation of the organism over such ‘luxuries’ as growth and reproduction.
细胞利用食物中的葡萄糖制造ATP(三磷酸腺苷)，该分子为身体的许多活动提供能量。通过限制食物的摄取量，可使进人细胞的葡萄糖降到最低，因此减少ATP的生成量。当食量正常的实验动物服用2DG时，葡萄糖大量进人细胞，但2DG会阻止大部分葡萄糖的代谢，因而降低ATP的合成量。研究人员提出了几种说法，解释为什么妨碍葡萄糖代谢与ATP合成可以延级衰老。其中一种说法与ATP生成过程中自由基的释放有关，人们认为自由基会损伤细胞，因此导致衰老以及像癌症这类与衰老有关的疾病。减少ATP生成机制的运作次数可以限制自由基的数量，从而减少细胞受到的伤害。另一种假设认为，葡萄糖代谢的降低让细胞以为食物不足(即使事实并非如此)，而促使细胞进人抗衰老的状态，这种状态着重的是机体本身的维持，而不是生长或繁殖这类“奢侈活动”。