杂志antibiotics

杂志antibiotics

大众传媒的作用 The Function of Mass Media

As the development

the Inter, today we live in the high-tech world, we can have access

to all kinds of high-tech products, such as TV, puter and so on. The

Inter makes the world *** aller, we can know the instant news quickly.

years ago, we only have TV and radio to get the news, but now, we

have puter and cellphone. We call such product the mass media. The

mass media brings people a lot of fun, we can know the news from all

over the world, we are not just depending on the traditional media. Now

the government takes some action to clear the departments, the citizens

can supervisor the official. If people find the officials take the

advantage of the government’s resource, they can use the media to expose

such behavior. Mass media is weled by the audience, people not only

know more about the world, but also can supervisor the government.

As our society and economy develop quickly, it is important to cooperate with others because one man on his own isn't enough, so we must bine with others' power. Only by cooperation will the job be finished in a perfect way. There are many advantages in cooperation. First of all, it can save your valuable time and energy. Secondly, there are many opportunities to learn from each other. It is lucky enough if you cooperate with the person you like. You will feel enjoyable, and you would not mind sharing happiness and hardship with your partners. On the contrary, unfortunately, if the person with whom you cooperate is offensive, you should try your best to tolerate his or her shorting. Believe it or not, everyone possesses advantages; you will be able to dig out his or her r, you should believe in your partner because your faith will give him more confidence. And you must treat your partner honestly.

题目...

The increasing popularity of the news media makes it now of really powerful force and easy to be harnessed to cause negative influence. This is because many news media panies tend to broadcast sensational news in order to attract audience's attention and therefore get a high viewing ratings. This can easily lead to the false report which can distort the public's values and at the same time destroy an innocent person's life, for instance, a report on a crime without actual investigation.

这时，小毛驴看见一个驮着几十袋面粉，脚下踩着四个轮子的大家伙飞驰而过。

小毛驴不想被超过，就使足全身力气追啊追啊，累得满头大汗、气喘吁吁，可还是没追上。

等他来到市场的时候，大家伙已经卸完面粉准备回家了。

小毛驴无精打采地来到摊主身边，问：“那个家伙是谁呀？跑得那么快！”摊主说：“那个家伙是卡车。

”

The effect of media in our life There are many types of media such as: television, news paper, magazine, radio, inter, cinema, phones and many more. Media is important and also have positive effect on people's life. Because it shows people the world's news, and it have advantage to educate the children also, the media has an important educational and joyment media have positive effect to show the people all news on the world. Now a day's, the world became like *** all village because of media effect. The media spread knowledge, information and news for the states, regions and cities too. For example: We can know every thing about the war on any place or the risks around us also, the media tell us on the television or the radio about the weather if it is bad or good so we will take our precautions or even we might change our plans if the weather won't permit . Also, it tells us about natural disaster for example: hurricanes, tornados, storms, tsunami such as the tsunami that happened on the south east of Asia. So we saw the events as if we are there. Also inter or phones can be used for munication with our family any time and we can hear their voice and see their images for example, skype, hotmail and yahoo messenger programs. The media have an interest in many aspects: education, fun, medical, documentary, and sport. The education programs help people who want to learn something by TV or inter for example: some people learn English language online on the inter. The documentary program which I always like to watch such as programs about animals, jangle, sea life or old nation…etc. Finally, media has many benefits for kids especially children learn many things from TV that they can't see it on the nature such as some animals forms and sound as cow, cat, horse ..ect. Also intellectual and skill develop- mental programs that teach kids painting ,drawing, and inventing things such as program in tree house channel called Mr. Maker that teach children how to make there toys. Media is important for children who want to learn second language; that will help them to get English quickly for example my son always watches the kids channel that helped him to learn English swiftly.

The experts warn we're at the dawn of a post-antibiotic era. Immediate global action is needed, they say, if dire consequences are to be avoided within just a few years. This would involve cutting down on the unnecessary prescription of antibiotics and providing incentives to pharmaceutical panies to develop new drugs. Research would be needed into how antibiotics in farming affect the growth of drug-resistant strains of bacteria. The experts warn that without effective antibiotics, treatments ranging from minor surgery to current cancer chemotherapy regimes could bee impossible and that deaths from infections in developed countries might return to levels last seen in the early 20th century. They also say healthcare costs would probably spiral, as we'd be forced to resort to newer, more expensive drugs and stay in hospital for longer when recovering from illness.

The Media and Famous People In almost every form of media,including television,newspapers and magazines,a great deal of attention is paid to the personal lives of seems that the public cannot get enough of this kind of r,I believe that the media have a responsibility to present a balanced view of the world,as well as respect the lives of public ore,I believe that the media pay too much attention to the personal lives of famous people. For people who are fascinated with the lives of public figures there are some forms of media devoted exclusively to this can satisfy their curiosity by buying fan magazines and watching TV shows devoted to entertainment general media should present all types of information because people have different rmore,the practice of dwelling on the private lives of celebrities can lead people to pay more attention to these matters than they otherwise s most importantly,the media should respect the privacy of every individual,including public may have chosen to be in the public eye,but that does not give the public the right to know everything about er,many stories about celebrities are untrue; they are only gossip reported to increase sales of magazines and other are unfair to the famous and mislead the public. For all of these reasons,I believe that the media should pay more attention to matters other than the private lives of public this way,they can appeal to a wider audience and encourage people to develop other my opinion,the media currently pay too much attention to the private lives of public figures. 参考译文： 媒体与名人 几乎每一种媒体，包括电视、报纸和杂志，都把许多焦点放在名人的私生活上.一般大众似乎对这种新闻一直很感兴趣.然而，我认为媒体有责任以公正无偏袒的观点报导时事，以及尊重公众人物的生活.因此，我认为媒体的确过度关注名人的私生活. 因为有些人对于公众人物的私生活十分着迷，所以有些媒体就专做这个主题.通过购买针对歌迷或影迷所发行的杂志和观看电视节目的娱乐新闻，就能满足这些歌迷和影迷的好奇心.一般媒体应该提供所有类型的资讯，因为人们的兴趣各不相同.此外，老是强调名人的私生活，会使人们比平常更注意这些事情.或许最重要的是，媒体应该尊重个人的隐私，包括公众人物的隐私.他们可能选择公开露面或上传播媒体，但那并不表示大众有权知道他们的一切.此外，许多关于名人的报导并不真实；那些报导只不过是被用来增加杂志销售量以及其他媒体业绩的八卦传闻.那些不实的报导不仅对名人不公平，也会误导大众. 基于这些理由，我认为媒体应该多注意公众人物私生活以外的事情.如此一来，媒体就能吸引更广大的受众群，并且鼓励人们培养其他的兴趣.依我之见，目前的媒体的确过度关注公众人物及他们的私生活.

我试试吧~An introduction to English Weekly Now I want to introduce a sort of newspaper to is English 1983 it was its first time to be punished by Shanxi Normal is the newspaper that is for more than one kind of pepple such as the students in high school and middle school,the teachers and the reading is the newspaper that more and more people is the newpaper that can be published the most of all the number English Weekly published is near 16000000 !There are some sections on it, such as domestic news, sports and entertainment, answers for difficulties and various interesting is designed by simple language with illustrations, it can help us enlarge our vocabulary and improve our English level

争议 最近一些年发生在新闻界的一个值得关注的现象就是传统媒体的人才在向新媒体流动，要知道传统媒体的很多人至今为止仍然是看不起新媒体的，因为看上去新媒体和旧媒体比较，它依然不像是媒体，或者说不是我们传统意义上的媒体。

但是，问题也许正在于此，新媒体为什么非要像媒体？你也可以把它叫做新媒介，媒介和媒体的概念似乎正在被打破。

在很长一段时间里，传统媒体的许多人一直秉持着一种媒体思维，以媒体自居，以做媒体人为骄傲，在他们眼里，新媒体终归不是媒体，不是正规军，是散兵游勇。

那么，在这种情况下，我们可以来看看传统媒体对人才的需求产生了什么样的变化，换句话说，它们今天更需要什么样的人才？

U.S. Vice President Mike Pence swore in Betsy DeVos as U.S. secretary of education on Tuesday after casting the tie-breaking Senate vote to confirm President Donald Trump's controversial nominee. It was the first time in American history that a vice president had been needed to get a Cabi pick approved.美国副总统彭斯主持了教育部长贝齐？德沃斯的宣誓就职仪式。

美国国会参议院星期二在彭斯投下打破平衡的一票后，批准了川普总统这位极具争议的教育部长人选。

这是美国历史上第一次在审批内阁人选时需要副总统投出的一票。

DeVos pledged at her swearing-in to ＂support and defend the United States against all enemies, foreign and domestic.＂ In the words of her official vow, she also pledged to ＂well and faithfully＂ discharge the duties of her office.德沃斯星期二晚上宣誓时说，她将“支持和捍卫美国对抗所有敌人，无论来自国外还是国内”。

她在官方誓词中说，她将保证“好好地、忠实地”履行她的职责。

The ceremony took place quickly and without fanfare, except for the whirring and clicking of cameras and other media equipment. After the short ceremony was over, a *** all audience of family and friends burst into polite applause.宣誓就职仪式快速完毕，没有喧闹，只有照相机的快门声和其他媒体设备的响声。

在短暂的仪式结束后，一小群旁观的家人和朋友发出礼貌的掌声。

Earlier in the day, o Republicans voted with a united Democratic caucus in opposition to DeVos. The result was a 50-50 split before Pence cast the deciding vote, as the Constitution mandates when the chamber is evenly divided.星期二早些时候，两名参议院共和党人投票站在了团结一致反对德沃斯任命的民主党人一边，导致支持和反对票数为50-50，副总统彭斯按宪法规定在参议院各执一词时投出了决定性一票。

Media in China Compared to enty years ago, media is growing fast in China. TV sales have been increasing very quickly. Modern media has changed Chinese culture by erasing traditional thinking. Nowadays, fewer people live in the traditional Chinese style building. Modern media has made China a very different by changing people's life style. In China, people are more likely to stay at home rather than going out. Because modern media changes the way people work and gather information . In the past, people got information from their neighbours or at work because most of them were not well educated which means they could hardly read or write. Communication was the only way to interact with each other, which could limit the way of gathering information. However, in a modern society, people can get their knowledge in multiple ways, such as Inter, TV & newspapers. Thus, modern media gives people a greater range of getting knowledge. On the other hand, modern media helps people get information quickly and easily. For instance, people can get information from long distance in a short time by making a phone call. In the past, people talked to their neighbours to pass information, which is a waste of time. As a result, Chinese culture has been positively affect by modern media. Inter, as a great contribution to human society development, also affect Chinese culture in a silent way. In the modern era, people prefer to municate by Inter rather than going out because it's fortable and convenient to stay at home use the chatting tools. That causes people's connection to be reduced, which means people are not close to each other anymore. In other words, modern media has changed people's relationships in China. Modern media has changed Chinese culture by erasing the traditional life style. People are more likely to stay at home rather than going out. Their personal connections have decreased dramatically. Moreover, modern media helps people get information quickly and easily. However, this trend will never stop, Chinese culture will change by modern media more and more to adapt the new world.

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谁能帮我找一篇与微生物有关的英文文章``````

A microorganism (also can be spelled as micro organism) or microbe is an organism that is microscopic (too small to be seen by the naked human eye). The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design.

Microorganisms are incredibly diverse and include bacteria, fungi, archaea, and protists, as well as some microscopic plants and animals such as plankton, and popularly-known animals such as the planarian and the amoeba. They do not include viruses and prions, which are generally classified as non-living. Most microorganisms are single-celled, or unicellular, but some multicellular organisms are microscopic, while some unicellular protists, and a bacteria called Thiomargarita namibiensis are visible to the naked eye.

Microorganisms live in all parts of the biosphere where there is liquid water, including hot springs, on the ocean floor, high in the atmosphere and deep inside rocks within the Earth's crust. Microorganisms are critical to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle, and recent studies indicate that airborne microbes may play a role in precipitation and weather.

Microbes are also exploited by people in biotechnology, both in traditional food and beverage preparation, as well as modern technologies based on genetic engineering. However, pathogenic microbes are harmful, since they invade and grow within other organisms, causing diseases that kill millions of people, other animals, and plants.

History
Evolution
Single-celled microorganisms were the first forms of life to develop on earth, approximately 3–4 billion years r evolution was slow,and for about 3 billion years in the Precambrian eon, all organisms were microscopic. So, for most of the history of life on Earth the only form of life were ia, algae and fungi have been identified in amber that is 220 million years old, which shows that the morphology of microorganisms has changed little since the triassic period.

Most microorganisms can reproduce rapidly and microbes such as bacteria can also freely exchange genes by conjugation, transformation and transduction between widely-divergent species.[10] This horizontal gene transfer, coupled with a high mutation rate and many other means of genetic variation, allows microorganisms to swiftly evolve (via natural selection) to survive in new environments and respond to environmental stresses. This rapid evolution is important in medicine, as it has led to the recent development of 'super-bugs' — pathogenic bacteria that are resistant to modern antibiotics.

Pre-Microbiology
The possibility that microorganisms might exist was discussed for many centuries before their actual discovery in the 17th century. The first ideas about microorganisms were those of the Roman scholar Marcus Terentius Varro in a book titled On Agriculture in which he warns against locating a homestead near swamps:

“ …and because there are bred certain minute creatures which cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and there cause serious diseases.”

This passage seems to indicate that the ancients were aware of the possibility that diseases could be spread by yet unseen organisms.

In The Canon of Medicine (1020), Abū Alī ibn Sīnā (Avicenna) stated that bodily secretion is contaminated by foul foreign earthly bodies before being also hypothesized that tuberculosis and other diseases might be contagious, i.e. that they were infectious diseases, and used quarantine to limit their spread.

When the Black Death bubonic plague reached al-Andalus in the 14th century, Ibn Khatima wrote that infectious diseases were caused by "contagious entities" that enter the human body. Later, in 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances.

All these early claims about the existence of microorganisms were speculative in nature and not based on any data or science. Microorganisms were neither proven, observed, nor correctly and accurately described until the 17th century. The reason for this was that all these early inquiries lacked the most fundamental tool in order for microbiology and bacteriology to exist as a science, and that was the microscope.

Discovery
Anton van Leeuwenhoek was the first person to observe microorganisms, using a microscope of his own design, thereby making him the first microbiologist. In doing so Leeuwenhoek would make one of the most important contributions to biology and open up the fields of microbiology and bacteriology. Prior to Leeuwenhoek's discovery of microorganisms in 1675, it had been a mystery as to why grapes could be turned into wine, milk into cheese, or why food would spoil. Leeuwenhoek did not make the connection between these processes and microorganisms, but using a microscope, he did establish that there were forms of life that were not visible to the naked nhoek's discovery, along with subsequent observations by Lazzaro Spallanzani and Louis Pasteur, ended the long-held belief that life spontaneously appeared from non-living substances during the process of spoilage.

Lazzarro Spallanzani found that microorganisms could only settle in a broth if the broth was exposed to the air. He also found that boiling the broth would sterilise it and kill the microorganisms. Louis Pasteur expanded upon Spallanzani's findings by exposing boiled broths to the air, in vessels that contained a filter to prevent all particles from passing through to the growth medium, and also in vessels with no filter at all, with air being admitted via a curved tube that would not allow dust particles to come in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within the broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur's experiment. This meant that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and supported germ theory.

In 1876, Robert Koch established that microbes can cause disease. He did this by finding that the blood of cattle who were infected with anthrax always had large numbers of Bacillus anthracis. Koch also found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, causing the healthy animal to become sick. He also found that he could grow the bacteria in a nutrient broth, inject it into a healthy animal, and cause illness. Based upon these experiments, he devised criteria for establishing a causal link between a microbe and a disease in what are now known as Koch's these postulates cannot be applied in all cases, they do retain historical importance in the development of scientific thought and can still be used today.

Classification and structure
Microorganisms can be found almost anywhere in the taxonomic organization of life on the planet. Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic, including most protists, some fungi, as well as some animals and plants. Viruses are generally regarded as not living and therefore are not microbes, although the field of microbiology also encompasses the study of viruses.

[edit] Prokaryotes
Prokaryotes are organisms that lack a cell nucleus and the other organelles found in eukaryotes. Prokaryotes are almost always unicellular, although some species such as myxobacteria can aggregate into complex structures as part of their life cycle. These organisms are divided into two groups, the archaea and the bacteria.

Bacteria
Bacteria are the most diverse and abundant group of organisms on Earth. Bacteria inhabit practically all environments where some liquid water is available and the temperature is below +140 °C. They are found in sea water, soil, air, animals' gastrointestinal tracts, hot springs and even deep beneath the Earth's crust in rocks.[20] Practically all surfaces which have not been specially sterilized are covered in bacteria. The number of bacteria in the world is estimated to be around five million trillion trillion, or 5 × 1030.

Bacteria are practically all invisible to the naked eye, with a few extremely rare exceptions, such as Thiomargarita are unicellular organisms and lack membrane-bound organelles. Their genome is usually a single loop of DNA, although they can also harbor small pieces of DNA called plasmids. These plasmids can be transferred between cells through bacterial conjugation. Bacteria are surrounded by a cell wall, which provides strength and rigidity to their cells. They reproduce by binary fission or sometimes by budding, but do not undergo sexual reproduction. Some species form extraordinarily resilient spores, but for bacteria this is a mechanism for survival, not reproduction. Under optimal conditions bacteria can grow extremely rapidly and can double as quickly as every 10 minutes......

微生物是指一切肉眼看不到或看不清楚，因而需要借助显微镜观察的微小生物。微生物包括原核微生物（如细菌）、真核微生物（如真菌、藻类和原虫）和无细胞生物（如病毒）三类。

主要特性
微生物最大的特点，不但在於体积微小，而且在结构上亦相当简单。由於微生物体积极之微小，故相对面积较大，物质吸收快，转化快。微生物在生长与繁殖上亦是很迅速的，而且适应性强。从寒冷的冰川到极酷热的温泉，从极高的山顶到极深的海底，微生物都能够生存。

由於微生物适应性强，又容易在较短时间内积聚非常多的个体（例如10^10个/毫升的数量级），因此容易筛选并分离到突变株。容易得到微生物突变株的性质，给人类利用与开发微生物带来广阔契机，但也是导致抗药性的内在原因。

微生物的代谢
微生物的代谢指微生物（细胞）内发生的全部化学反应。 微生物的代谢异常旺盛，这是由於微生物的表面积与体积比很大（约是同等重量的成年人的30万倍），使它们能够迅速与外界环境进行物质交换。

代谢产物 微生物在代谢过程中，会产生多种代谢产物。根据代谢产物与微生物生长繁殖的关系，可以分为初级代谢产物和次级代谢产物两类。 初级代谢产物是指微生物通过代谢活动产生的、自身生长和繁殖所必须的物质，如氨基酸、核苷酸、多糖、脂质、维生素等。在不同种类的微生物细胞中，初级代谢产物的种类基本相同。 次级代谢产物是指微生物生长到一定阶段才产生的化学结构十分复杂，对该微生物无明显生理功能，或并非是微生物生长和繁殖所必须的物质，如抗生素、毒素、激素、色素等。不同种类的微生物所产生的次级代谢产物不相同，它们可能积累在细胞内，也可能排到外环境中。

代谢的调节 微生物在长期的进化过程中，形成了一整套完善的代谢调节系统，以保证证代谢活动经济而高效地进行。微生物的代谢调节主要有两种方式：酶合成的调节和酶活性的调节。 另外人工控制微生物代谢的措施包括改变微生物遗传特徵，控制生产过程中的各种条件等。

主要分类
微生物主要分为以下几类：（参见生物分类总表）

原核微生物
细菌(Bacteria)
古菌(Archaea)
真核微生物
真菌(Fungi)
原生生物(protozoan)
藻类(algae)
无细胞生物
病毒(virus)
类病毒(virusoid)
拟病毒(viroid)
朊毒体（亦称朊病毒、蛋白质质感染性颗粒）(prion)

微生物在自然界的存在
微生物在自然界中广泛存在，数目巨大。下表为一些生态环境中微生物细胞数目的估计：

密度 全球总数
海水 108~109 L-1 约1029
海洋沉积物 109 g-1 约3×1029
动物消化道 1011 g-1 约1025
地表或海底下深处 102~108 约1030

原核生物共构成全球生物量的25~50%。

微生物的作用
微生物与人类的生产、生活和生存息息相关。有很多食品（如酱油、醋、味精、酒、酸奶、奶酪、蘑菇）、工业品（如皮革、纺织、石化）、药品（如抗生素、疫苗、维生素、生态农药）是依赖于微生物制造的；微生物在矿产探测与开采、废物处理（如水净化、沼气发酵）等各种领域中也发挥重要作用。微生物是自然界唯一认知的固氮者（如大豆根瘤菌）与动植物残体降解者（如纤维素的降解），同时位于常见生物链的首末两端，从而完成碳、氮、硫、磷等生物质在大循环中的衔接。若没有微生物，众多生物就失去必需的营养来源、植物的纤维质残体就无法分解而无限堆积，就没有自然界当前的繁荣与秩序或人类的产生与维续。

此外，微生物对地球上气候的变化也起着重要作用。许多微生物直接参与了温室气体的排放或者吸收，而也有很多微生物可以成为未来的生物燃料[1]。

微生物与人类健康
微生物与人类健康密切相关。多数微生物对人体是无害的。实际上，人体的外表面（如皮肤）和内表面（如肠道）生活着很多正常、有益的菌群。它们占据这些表面并产生天然的抗生素，抑制有害菌的着落与生长；它们也协助吸收或亲自制造一些人体必需的营养物质，如维生素和氨基酸。这些菌群的失调（如抗生素滥用）可以导致感染发生或营养缺失。然而另一方面，人类与动植物的疾病也有很多是由微生物引起，这些微生物叫做病原微生物(pathogenic microorganism)或病原(pathogen)。重要的人类致病微生物列于下表中。

主要的人类致病微生物 疾病名称 致病原 全球感染（携带者）人数 每年新发病例数 每年死亡人数
结核 结核分枝杆菌 ~20亿人（全球三分之一人口） 881万例 (2003 [1]) 175万人 (2003 [2])
艾滋病 人类免疫缺陷病毒 4200万人 550万例 310万人
痢疾 志贺氏菌、痢疾杆菌、大肠埃希氏杆菌等 27亿例 190万人
疟疾 疟原虫 3-5亿例 100万人
乙型肝炎 乙型肝炎病毒 1000-3000万例 100万人
麻疹 麻疹病毒 3000万例 90万人
登革热 登革病毒 2000万例 2万4千人
流感 流感病毒 几乎全部人口 300-500万例 25万人
黄热病 黄热病毒 20万例 3万人

其他经常听说的致病微生物还有：流行已经完全得到控制或消灭的天花病毒（引起天花）和脊髓灰质炎病毒（导致小儿麻痹症）；引起炭疽病的炭疽杆菌；以及近年来显现的萨斯冠状病毒（引起严重急性呼吸道综合症，又名萨斯、也俗称非典型肺炎）和可能将在人类流行的禽流感。

对现代生物学研究与医学技术的贡献
现代生物学的若干基础性的重大发现与理论，是在研究微生物的过程中或以微生物为实验材料与工具取得的。这些理论包括：

证明DNA（脱氧核糖核酸）是遗传信息的载体（三大经典实验：肺炎球菌的转化实验、噬菌体实验、植物病毒的重组实验）
DNA的半保留复制方式（双螺旋的每一条子链分别、都是复制模板）
遗传密码子的解读（64个密码子各对应20种氨基酸及终止信号的哪一种）
基因的转录调节（operon, promoter, operator, repressor, activator的概念与调节方式）
信使RNA的翻译调节（terminator）
等等……（请添加）
现在，很多常用、通用的生物学研究技术依赖于微生物，比如：

分子克隆
重组蛋白在细菌或酵母中的表达
很多医学技术也依赖于微生物。比如：

以病毒为载体的基因治疗

小孩子吃一次抗生素7天不发育？

想要了解为什么，我们还得从头说起。

什么是抗生素？

抗生素（antibiotics）是由细菌、霉菌或其他微生物在生活过程中所产生的具有抗病原体或其它活性的次生代谢有机物。抗生素既不参与细胞结构，也不是细胞的贮存养料；对产生抗生素的菌无害，但对其他微生物则有特定专一的作用；在有效浓度很低的情况下，能够抑制敏感菌种的生长和代谢活性或将其致死。

也就是说，抗生素是某些生物的代谢产物，他们能够起到破坏某种特定细胞的作用。

抗生素是如何起作用的？

抗生素的作用机理主要是影响病原微生物的结构和干扰其代谢过程，主要包括：抑制核酸的合成、抑制蛋白质的合成、改变细胞膜的通透性、干扰细胞壁的合成、作用于能量代谢系统或作为抗代谢物。

那么所谓给人体造成细菌感染的细菌又是什么样子呢？请看下图。

细菌是一种单细胞原核生物，图中所示的基本结构是指细菌一定会有结构，而特殊结构是根据细菌的种类不同有可能出现的结构。抗生素的功能就是破坏其中某一种结构从而达到抑制细菌繁殖或杀死细菌的目的。例如，核质（也称核仁）是细菌的DNA物质，如果被破坏就无法再进行繁殖；细胞膜的通透性关系到细胞内外液体的交换；细胞壁是坚硬的外壳，有保护细菌的作用。不同的抗生素会对不同细菌的不同结构起作用。

抗生素对身体有没有危害？

抗生素只针对特定的细胞有效果，被筛选出作为药物的抗生素都是专门针对致病菌的，并不伤害人体正常的细胞。也许有人会问，那么“抗生素杀白血球”又是怎么回事呢？白细胞是人体自身免疫系统中吞噬有害细菌的细胞，因此有细菌感染时，体内白细胞自然会高于正常水平，而当抗生素开始起作用后，炎症得到缓解，细菌少了，吞噬细菌的白细胞自然也就少了，并非是抗生素杀死了白细胞。

有些药物会抑制骨髓中的造血干细胞分化为白细胞，用药后，就会出现体内白细胞数量过低的情况，不过抗生素没有这个作用，一些化疗药物才有这种副作用。

如果没有危害，为什么近年来一直强调要禁止滥用抗生素呢？

在某一人群中反复应用抗生素会导致敏感菌株逐渐减少，人为造成耐药菌株被筛选出来的情况。耐药菌株繁殖后在人群中传播，一旦被感染，会导致日后治疗更加困难。

另外，由于儿童的身体尚未发育完全，过量服用抗生素会加重肝、肾等内脏的代谢负担。

不过，抗生素针对儿童都会减少剂量，而且目前医院普遍建议连续服用三天后即停药。只要遵医嘱正常服用，对身体是没有危害的。

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参考文献：

[1]孟宁生. 抗生素的抗菌作用机理[J]. 集宁师专学报,2009,04:37-39.

[2]李绍英,沈叙庄,王艳,杨永弘,俞桑洁. 5岁以下儿童门诊呼吸道感染常见病原携带及抗生素耐药的流行病学特征调查[J]. 中国实用儿科杂志,2004,04:212-216.

[3]建宇,李杨,文竹. 家长“迷信”抗生素 儿童生病易“受害”[J]. 光明中医,2008,12:1879.

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