爱华网《新概念英语》是一套畅销全球的英语学习书籍,深受中国学生的喜爱。下面是小编带来的新概念英语文章，欢迎阅读!
新概念英语文章1Bacteria
细菌
Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micron is a thousandth of a millimeter: a pinhead is about a millimeter across. Rod-shaped bacteria are usually from two to four microns long, while rounded ones are generally one micron in diameter. Thus if you enlarged a rounded bacterium a thousand times, it would be just about the size of a pinhead. An adult human magnified by the same amount would be over a mile tall.
细菌是极其微小的生物体。我们用英寸或厘米来测量自己的大小，而测量细菌却要用微米。一微米等于千分之一毫米。针头直径大约一毫米。棒状细菌通常有2-4微米长，而圆形细菌的直径一般只有1微米。因此，即使你把一个圆形细菌放大1000倍，它也不过一个针头那么大。可是如果把一个成年人放大1000倍，就会变成1英里(或1.6公里)多高。
Even with an ordinary microscope, you must look closely to see bacteria. Using a magnification of 100 times, one finds that bacteria are barely visible as tiny rods or dots. One cannot make out anything of their structure. Using special stains, one can see that some bacteria have attached to them wavy-looking "hairs" called flagella. Others have only one flagellum. The flagella rotate, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can glide along over surfaces by some little-understoodmechanism.
用一般的显微镜观察细菌时，你必须仔细观察才能看见它们。使用100倍的显微镜时，你会发现细菌不过是隐约可见的小细棒或小点点，而它们的结构你却根本看不出来。使用特殊的着色剂后，你会发现有的细菌上长着不少波状的"毛发"即鞭毛，而有的细菌只有一根鞭毛。鞭毛的旋转可以推动细菌在水中行进。不少细菌没有鞭毛，因而不能自己行进。还有些细菌却能通过某些鲜为人知的机制沿物体表面滑动。
From the bacteria point of view, the world is a very different place from what it is to humans. To a bacterium water is as thick as molasses is to us. Bacteria are so small that they are influenced by the movements of the chemical molecules around them. Bacteria under the microscope, even those with no flagella, often bounce about in the water. This is because they collide with the watery molecules and are pushed this way and that. Molecules move so rapidly that within a tenth of a second the molecules around a bacteria have all been replaced by new ones; even bacteria without flagella are thus constantly exposed to a changing environment.
我们所熟知的世界在细菌眼中完全是另一个样子。对于细菌来说，水就同糖浆之于人类一样稠密。细菌是如此的微小，周围化学分子的一举一动都会对它们产生影响。在显微镜下，细菌，甚至包括那些没有鞭毛的细菌，经常在水中跳来跳去。这是因为它们与水分子相撞后，被弹向各个方向。分子移动很迅速，仅0.1秒之隔，一个细菌周围的分子就会完全更新。因此，即使是没有鞭毛的细菌也暴露在一个不断变化的环境中。
新概念英语文章2Sleep
睡眠
Sleep is part of a person's daily activity cycle. There are several different stages of sleep, and they too occur in cycles.
睡眠是人每天日常活动循环的一部分。人的睡眠分几个阶段，而这些阶段也是循环发生的。
If you are an average sleeper, your sleep cycle is as follows. When you first drift off into slumber, your eyes will roll about a bit, your temperature will drop slightly, your muscles will relax, and your breathing well slow and become quite regular. Your brain waves slow down a bit too, with the alpha rhythm of rather fast wavespredominating for the first few minutes. This is called stage 1 sleep. For the next half hour or so, as you relax more and more, you will drift down through stage 2 and stage 3 sleep. The lower your stage of sleep, the slower your brain waves will be. 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.
如果你是一个正常的睡眠者，你的睡眠循环会这样进行。在你开始昏昏入睡时，你的眼睛会滚动几下，体温略有下降，肌肉放松，呼吸变得缓慢而有节奏。除了开始几分钟比较快的α节奏外，脑电波也稍有减缓。这被称为第一阶段睡眠。在随后约半小时内，你进一步放松，进入第二和第三阶段睡眠。睡眠越深入，脑电波就越缓慢。大约在开始睡眠后的40到60分钟，你将进入沉睡状态。这时的脑电波表现为巨大的缓波，被称为δ节奏。这就是第四阶段睡眠。
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. The delta rhythm will disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to dart around under your closed eyelids as if you were looking at something occurring in front of you. This period of rapid eye movement lasts for some 8 to 15 minutes and is called REM sleep. 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.
但你并不是整夜都保持这种沉睡状态。入睡后约80分钟左右，你的大脑运动水平会再度略有提高。δ节奏消失，并被脑电波的运动图形取代。你的眼睛会在闭着的眼睑下迅速转动，就好象你在看着眼前发生的什么事情。这种迅速的眼球运动持续约8-15分钟，这一阶段睡眠被称之为快速眼动(REM)睡眠。在REM睡眠阶段，你的肢体会很快再度放松，呼吸也再次放慢并变得有节奏，你会轻松地从第一阶段滑入第四阶段睡眠——直到大约80分钟后重新接近清醒状态。
新概念英语文章2Cells and Temperature
细胞与温度
Cells cannot remain alive outside certain limits of temperature, and much narrower limits mark the boundaries of effective functioning.
细胞只能在一定的温度范围内存活，而进一步保证它们有效工作的温度范围就更小了。
Enzyme systems of mammals and birds are most efficient only within a narrow range around 37℃; a departure of a few degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations, the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature.
哺乳动物和鸟类的酶系统只能在37℃左右的很小范围内才能有效工作。与此相差仅几度的温度都会大大削弱它们的工作效率。尽管温度变化更大时细胞仍能存活，但机体系统的整体运行能力却被削弱了。其它动物对体温的变化有更强的适应性。
For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperature. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into "warm blooded" and "cold blooded" species; warm-blooded included mammals and birds whereas all other creatures were considered cold-blooded. As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana-- each cold-blooded -- usually has a body temperature only a degree or two below that of humans and so is not cold.
几个世纪以来，人们就认识到哺乳动物和鸟类调节体温的方式与其它动物不同。随着时间的推移，人们对这种差异的描述越来越精确和有意义，但是“暖血动物”和“冷血动物”这一古老的分类方式至今仍在大众词汇中有所反映。暖血动物包括哺乳动物和鸟类，其它动物统统被视为冷血动物。但是对更多物种进行的研究表明这种分类显然是不适当的。美洲一种小型蜥蜴和沙漠鬣蜥同属冷血动物，但实际上它们的体温通常只比人类的体温低1-2度，因此并不是真正的冷血。
Therefore the next distinction was made between animals that maintain a constant body temperature, calledhomeotherms, and those whose body temperature varies with their environment, called poikilotherms. But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation. Furthermore, many invertebrates that live in the depths of the ocean never experience changes in the chill of the deep water, and their body temperatures remain constant.
因此又出现了恒温动物(即保持恒定体温的动物)和变温动物(即体温随外界环境的变化而改变的动物)这一区分方式。但这种分类也不恰当。因为有不少哺乳动物在冬眠期间会改变体温，而许多生活在深海的无脊椎动物在寒冷的深海水域中体温并不变化，而是恒定的。
