学科英语文摘
Academic English for Science & Technology
Text 1 (p4-6) How do computer hackers "get inside" a computer?
August 16, 2004 Julie J.C.H. Ryan, an assistant professor at The George Washington University and co-author of Defending Your Digital Assets Against Hackers, Crackers, Spies, and Thieves, explains.
1.This seems like a straightforward question but it’s actually quite complex in its implications,
and the answer is anything but simple. The trivial response is that ‘hackers get inside a target computer system by exploiting vulnerabilities,’ but in order to provide more detail, let’s start from the beginning.
2.The term ‘hacker’ is fairly controversial in its meaning and interpretation. Some people
claim that hackers are good guys who simply push the boundaries of knowledge without doing any harm (at least not on purpose), whereas ‘crackers’ are the real bad guys. This debate is not productive; for the purposes of this discussion, the term ‘unauthorized user’(UU) will suffice. This moniker covers the entire spectrum of folks, from those involved in organized criminal activities to insiders who are pushing the limits of what they are authorized to do on a system.
3.Next let’s explore what it means to ‘get inside’a computer. This can refer to gaining
access to the stored contents of a computer system, gaining access to the processing capabilities of a system, or intercepting information being communicated between systems. Each of these attacks requires a different set of skills and targets a different set of vulnerabilities.
4.So what do UUs take advantage of? Vulnerabilities exist in every system and there are
two kinds: known and unknown. Known vulnerabilities often exist as the result of needed capabilities. For instance, if you require different people to use a system in order to accomplish some business process, you have a known vulnerability: users. Another example of a known vulnerability is the ability to communicate over the Internet; enabling this capability, you open an access path to unknown and untrusted entities. Unknown vulnerabilities, which the owner or operator of a system is not aware of, may be the result of poor engineering, or may arise from unintended consequences of some of the needed capabilities.
5.By definition, vulnerabilities may be exploited. These can range from poor password
protection to leaving a computer turned on and physically accessible to visitors to the office. More than one technical exploit has been managed simply by sitting at the receptionist’s desk and using his computer to access the desired information. Poor passwords (for example, a username of ‘Joe Smith’ with an accompanying password of ‘joesmith’) are also a rich source of access: password cracking programs can easily identify dictionary words, names, and even common phrases within a matter of minutes.
Attempts to make those passwords more complex by replacing letters with numbers, such as replacing the letter O with the number zero, don’t make the task much harder. And when a UU can utilize a valid username-password combination, getting access to a system is as easy as logging in.
6.If a target system is very strongly protected (by an architecture that includes both
technical controls such as firewalls or security software, and managerial controls such as well defined policies and procedures) and difficult to access remotely, a UU might employ low-technology attacks. These tactics may include bribing an authorized user, taking a temporary job with a janitorial services firm, or dumpster diving (rifling through trash in search of information). If the target system is not so strongly protected, then a UU can use technical exploits to gain access.
7.To employ technical exploits a UU must first determine the specifications of the target
system. It would do no good whatsoever for a UU to use a technical exploit against a Microsoft vulnerability if the target system is a Macintosh. The UU must know what the target system is, how it is configured, and what kind of networking capabilities it has. Once these parameters (which can be determined remotely through a variety of methods) are known, then the UU can exploit the configuration’s known vulnerabilities. The availability of preprogrammed attacks for common configurations can make this task quite simple;
UUs that use these scripted capabilities are somewhat derisively known as ‘script kiddies.’8.One way a technically proficient UU can remotely determine the configuration of a target
system is through capabilities inherent in hypertext transfer protocol (http). Users who access certain Web sites actually send configuration information, such as the type of browser being used, to the requesting site. Once the system configuration is known, then exploits can be selected. An example of an exploit that takes advantage of system-specific vulnerabilities is described in the following statement from the U.S.
Computer Emergency Response Team (US CERT): ‘Exploit code has been publicly released that takes advantage of a buffer overflow vulnerability in the Microsoft Private Communication Technology (PCT) protocol. The vulnerability allows a remote attacker to execute arbitrary code with SYSTEM privileges.’
[see https://www.doczj.com/doc/8a14485804.html,/current/current_activity.html for more information] 9.Another type of attack is one that is preprogrammed against specific vulnerabilities and is
launched without any specific target--it is blasted out shotgun style with the goal of reaching as many potential targets as possible. This type of attack eliminates the need for the first step, but is less predictable in both outcome and effectiveness against any given target.
10.It’s important to recognize that the end goal of unauthorized access varies depending on
the UU’s motivations. For example, if a UU is trying to gather a lot of zombie computers for use in a distributed denial of service attack, then the goal is to sneak a client program onto as many computers as possible. One way to do this fairly effectively is through the use of
a so-called Trojan horse program, which installs the malicious program without the
knowledge or consent of the user. Some of more recent mass Internet attacks have had this profile as an element of the attack pattern.
11.Protecting yourself against attacks is a multistep process, which aims to limit and manage
the vulnerabilities of your system. (It’s impossible to eliminate them all.) First, make sure you have all the latest patches for your operating system and applications--these patches generally fix exploitable vulnerabilities. Make sure your password is complex: it should include letters, numbers, and symbolic characters in a nonsensical manner. Also, consider getting a hardware firewall and limiting the flow of data to and from the Internet to only the few select ports you actually need, such as e-mail and Web traffic. Make sure your antivirus software is up-to-date and check frequently to see if there are new virus definitions available. (If you are using a Windows system, you should ideally update your virus definitions every day.) Finally, back up your data. That way if something bad does happen, you can at least recover the important stuff.
Text 2 (p7-9) Introduction: Computer Viruses
11:04 04 September 2006 by Will Knight
Artist’s impression of computer bugs on a circuit board (Image: Vanessa Kellas/Rex Features)
1.Any computer connected to the internet faces a daunting range of electronic threats.
Perhaps the biggest single threat to any computer is the humble software bug. Seemingly innocuous programming errors can be exploited to force entry into a computer and also provide the weak spots that allow computer worms and viruses to proliferate.
2.Many software bugs will simply cause a computer to crash. But an expert programmer can
sometimes figure out how to make a computer malfunction in a creative way, so that it provides access to secure parts of a system, or shares protected data.
3.When a software vulnerability is revealed, it is often a race against the clock to apply the
correct software patch before an attacker can convert the bug into an "exploit" that can be used to cause major damage.
Viruses and worms
4. A computer virus is a program that spreads between computers by hiding itself within a -
seemingly innocent - document or application. A worm, on the other hand, is a program that replicates and travels without "infecting" anything else on a system.
5.Many modern specimens of malevolent code, however, use a mixture of tricks to cheat
their way onto computer systems, blurring the line between worms and viruses. The terms are now often used interchangeably.
6.The first worms appeared in the 1970s and spread slowly between computers connected
to the same network. They simply displayed an annoying message on the screen of each infected machine. The first computer virus, called Elk Cloner, was written in 1982 and infected computers via floppy disks.
Trojans and zombies
7.But viruses and worms no longer just provide a way for malevolent hackers to gain
notoriety. Today’s viral code can contaminate computers at lightning speed, spreading via email, peer-to-peer file-sharing networks and even instant messaging programs. The most successful ones cause serious damage, forcing companies around the globe to close down while infected computers are cleaned up.
8. A string of recent specimens have been designed to snatch passwords or credit card
information and install programs that can be used to remotely control infected machines.
These programs are known as trojan horses.
9.There is evidence that virus writers can earn large amounts of money by leasing access to
networks of compromised computers - often referred to as "botnets". These groups of remote-controlled "zombies" have been used to extort money from websites, by threatening to crash them with a denial-of-service (DoS) attack. This involves overloading
a server with bogus page requests, so that real messages cannot get through.
Spam, Spam, Spam
10.Spammers have also begun using botnets to forward unsolicited bulk email advertising, or
spam, through scores of zombie PCs. This makes it far more difficult for spam hunters to block the messages at source and catch the culprits.
11.Once considered a fairly minor problem, spam is rapidly spiralling out of control, and much
more than half of all email messages are now thought to consist of unwanted advertising messages.
12.To combat computer scientists’ best efforts to stem the tide of junk email, the spammers
have had to become more cunning and sophisticated. More recently, spim (spam by instant messenger) and spit (spam by internet telephony) have joined the fray.
Phishing
13.Spam’s more sinister cousin is the phishing email. This is a con trick that arrives as an
email and tries to trick a recipient into handing over money or sensitive personal information like their bank account details or a username and password.
14.The simplest phishing tricks try to dupe a target into sending money as part of a
get-rich-quick scheme. But phishing tricksters are also getting more devious and recent scams pose as customer service emails and send users to bogus banking or commercial websites where they are invited to "re-enter" their account information.
15.Some genuine sites have even proven vulnerable to software glitches that can be
exploited to capture information from regular users. Phishing is especially threatening because it can be used to steal a person’s digital identity.
Spyware
16.Along with spam and phishing, spyware represents the third of an unhappy trinity of
internet pests. These insidious and clandestine programs typically find their way onto a computer system alongside another, often free, software application, although some can also exploit software bugs to get onto a machine. The programs are used to serve up unwanted adverts, change system settings and gather information on a user’s online behaviour for marketing purposes.
Hackers
17.The term "computer hacker" was first coined in the 1960s and originally meant someone
capable of developing an ingenious solution to a programming problem. But the phrase has since fallen into disrepute, entering the popular vocabulary as a term for a programmer with criminal intent.
18.The earliest "criminal" hackers were in fact relatively harmless, interested in testing the
boundaries of their knowledge and their ability to get around security measures. They mainly performed innocuous pranks, for example employing low-tech tricks to get free calls through the US phone networks.
19.There are many tools in the modern hacking kit, including network scanners, packet
sniffers, rootkits and decompilers. But "social engineering" - for example, putting a particularly enticing message in an email header to encourage people to open it - and even search engines can also be useful weapons for the hacker.
Computer crime
20.As the number of computers networks has grown, so have the possibilities for more
serious misuse. And, as money increasingly becomes a digital commodity, the world has seen the emergence of serious computer criminals.
21.Criminal gangs have also started to get in on the action, attracted by the huge quantities
of money now spent online every day. There is evidence that unscrupulous experts can also earn serious money from crime syndicates by breaking into computer systems, writing viruses and creating phishing scams.
22.And it is not just ordinary desktop computers that are under threat. Governments, banks
and critical infrastructure can also be brought to a standstill by an expert armed only with a laptop computer and a net connection.
Mobile menace
23.The biggest new target for computer hackers is the mobile device. Virus writers are
already experimenting with code designed for smartphones and experts predict more may be on the way, while hackers are also looking at ways to crack handheld devices.
24.While the internet has transformed global communication beyond recognition, the arms
race between those intent on harnessing its power for criminal purposes and those tasked with preventing them has only just begun.
Text 5 (P44-46) Can you compete with A.I. for the next job?
By CLAUDE FISCHER, The Fiscal Times, April 14, 2011 1. A recent article in the New York Times described new computer software that in an instant
sifts through thousands of legal documents looking for a few litigable items, replacing hundreds of hours spent by lawyers reading the documents. This is not the start of a joke about how many lawyers you need to . . . but it does raise the question of how many lawyers you need. Economist-columnist Paul Krugman used the story to explain that computerization threatens to replace many white-collar jobs that are now held by college graduates. (And if you don’t need college graduates, do you need college professors?
Uh-oh.)
2.It did not help settle anxieties that the story appeared shortly after IBM’s Watson computer
beat two super-humans at Jeopardy. And now there are reports of software programs winning big pots on internet poker. The specter of automation unemploying us all may have finally arrived.
3.For decades, ages before personal computers, learned observers wrote about how
machines were going to replace humans –for better or for ill. Some worried that the masses of dispossessed workers would form a revolutionary mob; others suggested introducing people to uplifting hobbies, since we would have so much more leisure time on our hands. But the mass job shrinkage that these observers all expected did not come.
4.Has it finally come now?
Demands of a New Economy
5.The biggest occupational displacement in American history was the virtual end of farming.
Around the time of the Revolution, about 90 percent of Americans were involved in farming; they were farm owners, farm wives, farm kids, farm hands, farm slaves. Mostly they farmed to keep themselves alive and then farmed some more so they could barter or sell some surplus. Selling on the market became increasingly important in the 19th
century as roads, canals, and rails linked the farmers to towns and harbors. Big ships then took farmers’ crops to Europe. Farming increasingly became a cash business.
6.But as the agricultural industry grew, it needed fewer and fewer workers to produce a
bushel of corn, a gallon of milk, or a head of cattle. The absolute number of people who worked at farming and ranching hit its peak about 1910 – at around 11 or 12 million – and then the number dropped off rapidly. Today, agriculture provides fewer than two million jobs.
7.What happened? In great part, automation happened – better plows, planting and sowing
machines, harvesters –as did scientific farming, better seeds, and the like. Millions of farmers and farm hands now made superfluous had to move on. The percentage of American workers who were farmers dropped from that early 90 percent or so in 1800, to about 40 percent of the labor force in 1900 and then to under two percent in 2000.
8.Yet Americans as a whole were not automated out of work; the farmers – or more typically,
the farmers’ sons and daughters – found new kinds of jobs in a growing economy. A lot of those jobs were in manufacturing. Those jobs both paid better and usually provided better working conditions than did farming. That’s one reason every rural generation moaned about how hard it was to keep the kids down on the farm.
Machines That Run Machines
9.The early water- and-steam-powered factories that employed many formerly rural
Americans themselves displaced millions of craftsmen, a process some scholars have labeled “deskilling.” For example, early 19th-century shoemakers hand-crafted shoes, starting with the raw leather and ending with the laces, but by mid-century assembly-line shoes were undercutting their business. In one North Carolina town during the 1830s, church elder and shoemaker Henry Leinbach complained, “Rough times, these. It appears there is little love among us anymore . . ..” One of Leinbach’s neighbors who may have shown too little love wrote that she preferred to order her shoes from Philadelphia, because they “wear and fit better than any I have ever owned” – and they were probably cheaper, too. In place of craftsmen making shoes, machine-handling factory workers made them.
10.The number of factory jobs increased about six-fold between 1860 and 1920 (while the
population grew only about three-fold). The percentage of American workers in manufacturing rose from about 15 to about 25 percent. Then, the factory jobs got harder to find, in part because of automation. It was one reason – along with a shift to foreign suppliers – that the number of manufacturing jobs in the U.S. peaked in 1979 at 19 million.
That number dropped to 13 million in 2008, even before the Great Recession really hit. https://www.doczj.com/doc/8a14485804.html,lions of manufacturing jobs have gone away, as millions of farm and craft jobs went
away before. Yet, through all that, more new jobs appeared. Between 1960 and 2010, the population of the U.S. grew 1.7 times; but the number of employed Americans grew about
2.4 times. How can that be? Answer: The magic of growing productivity (combined with
mothers and immigrants joining the labor force to fill those jobs).
Savings Leads to Spending
12.The automation of farming, craft work, and manufacturing made products –most
importantly, food – incredibly cheaper. For example, around 1900 a pound of bread cost an American about half an hour of hard factory work; around 2000, a pound of fresher, more nutritious bread cost about five minutes of much easier work. The savings from cheaper food, shoes, and the like went into buying all sorts of new goods like cars and refrigerators and especially into paying service-providers: entertainers, doctors, waiters, teachers, software creators, bankers, police officers, yoga instructors, and the like. Many of the displaced farmers, craftsmen, and factory workers —or much more often, their children — ended up in pink-collar, white-collar, and professional jobs.
13.This story – tragic at the level of the displaced worker, happy at the level of the national
labor force – summarizes the work experience in America for centuries. Will it continue?
Will the computerization of, say, document-searching eliminate jobs today but yield savings that will create newer, perhaps better jobs tomorrow?
14.Or has history turned a corner? Is AI (artificial intelligence) a new sort of automation, one
that undercuts the brain work that became the mark of late-20th century employment, one that will only eliminate the better jobs? Will AI machines take over the best occupations such as systems analysts and biomedical engineers (paying humans about $75,000 a year) and leave people to be home health and personal care aides (at about $20,000 a year) – the four jobs that the Bureau of Labor Statistics currently expects will grow the fastest in the next decade?
15.The historical trend in American work suggests some optimism that better jobs for humans
are coming, but history also suggests that few trends move in the same direction for very long.
Text 9 (P66-70) Global Warming & Its Effects
Nicolas Dalleva 1.Each year the United States spends over 20 million dollars buying fossil fuels. This
country emits one fourth of the world’s greenhouse gases; the most prominent of these gases is carbon dioxide, which is released from the burning of fossil fuels. Global warming has been a global issue for many years now. Some countries and people claim to be only vaguely concerned with the cause because they were unaware or uninformed of the issue.
Roger Revelle, an oceanographer, helped to call out the problem to the public. After not receiving much feedback towards his cause, he criticized different governments in a jocular manner. He called warming “the great geophysical experiment.” He said, “The experiment is to load the atmosphere with as much carbon dioxide as possible, add a few other harmful gases, and see what happens.” Recently, several countries have been passing laws to prevent the world’s overheated destiny. Even with the setting of new rules and regulations, the earth continues to warm each year. Minimal efforts made to reduce the release of greenhouse gases, specifically carbon dioxide from the burning of fossil fuels, increase the rate and intensity of global warming.
2.The most prominent effect of global warming exists in the climate change over the past
years. Many people are unaware that global warming causes and changes all types of weather. The heating of the earth causes the magnitude and strength of weather conditions to increase. As the oceans get warmer, the intensity of hurricanes amplifies in power and devastation. In addition, many coastal cities and regions have recently been experiencing flooding, caused by the melting of the polar icecaps. The Arctic’s perennial icecaps decline in area by nine percent each year. In the past thirty years, over ten national records were set for the highest temperatures in the summer and winter.
Droughts and forest fires have been occurring dramatically more often in the past century.
All of these effects have been directly linked to the release of greenhouse gases.
3.Another area affected by global warming is the animal kingdom and nature. The number
of animals per specie has been decreasing annually due to harsh environmental changes.
As the polar icecaps melt, all creatures that live there are left without shelter. For example, as seal dens have been melting, the number of seals has dropped. Events that occur in the spring, such as mating, migrating, laying eggs, and returning from hibernation have been taking place approximately 5.1 days earlier than they were fifty years ago. The early occurrence of these events proves that the earth is getting warmer each year. More proof of warming is the evidence of many animals traveling farther from the equator as they
migrate. Although this change has been occurring with various creatures, butterflies and mosquitoes are being found the farthest from their natural habitats. Even though butterflies do not cause any known problems with the environment, mosquitoes are carries of malaria. This deadly disease has dangerously spread to new regions across the globe. If the world continues to warm, this issue, along with many others, will continue to grow.
4. A third type of evidence of global warming can be found in plants. Vegetation in an area
differs concurrently with the climate of that same area. Throughout many parts of the world, flowers bloom 7 days earlier and trees reproduce 10 days earlier, both since 1900.
As the growing seasons vary from very wet to very dry, agricultural growth cannot adapt.
In some recent years, regions’ crops have been both flooded and dried out. Due to the depletion of the ozone, many crops cannot survive. Another problem is the movement and increase of allergens. Carbon in the atmosphere allows plants to go through photosynthesis more rapidly, allowing allergens to grow in number. This evidence found throughout all of nature makes it very clear that global warming is a huge issue.
5. A combination of various actions and, in some cases, not enough action causes global
warming in the world today. The leading cause of global warming is the ongoing burning of fossil fuels, which releases carbon dioxide into the atmosphere. Carbon dioxide, along with the other greenhouse gases of methane, nitrous oxide, and chlorofluocarbons, is the cause of the greenhouse effect. This effect is dangerously increasing as the gases are being released in greater quantities. These gases not only build up to keep heat in the atmosphere, but they also thin the ozone layer. Some areas have been so thinned by the gases that there are holes present in the ozone. These dangerous holes allow harmful UV rays from the sun to reach the earth. UV rays are the main cause of skin cancer. As the earth continues to increase its pollution level each year, the number of skin cancer patients increases.
6.Because it releases carbon dioxide into the air, the burning of fossil fuels is an
environmentally harmful practice. Carbon dioxide can be absorbed by seawater. If the water is cold, it can hold more gas. Unfortunately, with global warming, the temperature of the oceans has been increasing. As the temperatures increase, more carbon dioxide is released. This vicious circle will continue to occur unless scientists cannot this from occurring. Particularly, petrol, or gasoline, is a leading source of the release of these carbon dioxide compounds. Petrol contains hydrocarbons that release carbon dioxide when they are burned. This reaction is unfortunately unavoidable. The only solution is a different fuel source. Carbon dioxide, once released, lasts up to 100 years in the atmosphere. It is the most abundant heat-absorbent gas besides water vapor, which is not considered as a greenhouse gas because it rains back to the earth in a continuous cycle.
The Mauna Loa Observatory has been measuring the level of carbon dioxide daily since 1958. Since their research began, the level in the atmosphere has drastically increased by
47 parts per million. Carbon dioxide makes up about one half of the causes of global
warming.
7.Although carbon dioxide largely harms the environment, the other greenhouse gases
have a large impact in the atmosphere. Methane, the next most prominent harmful gas, comes from cattle, asphalt, coal, oil, and rice fields. Lasting only ten years, methane absorbs thirty times more heat than carbon dioxide. Another greenhouse gas, nitrous oxide, lasts approximately 180 years and absorbs 200 times more heat than carbon dioxide. Nitrous oxide comes from microbes in soil that are found in fertilizers.
Slash-and-burn farming and the burning of some fossil fuels also emit nitrous oxide. The final greenhouse gas, chlorofluocarbon, lasts 400 years in the air and retains 16,000 times more heat. Chlorofluocarbons escape from various cooling systems. The combination of these four gases results in the retention of intense amounts of heat.
8.Throughout the world, various nations have been joining to help prevent or slow the
process of global warming. On February 3, 2007, French president, Jacques Chirac, proposed a new plan to prevent global warming. He st ated, “It’s our responsibility. The future of humanity demands it.” Forty-five nations, not including the United States, joined him in his efforts. Al Gore, however, is very involved with global warming and the greenhouse effect; he supports Chirac and plans to help. As it is the largest contributor to global warming, the United States unfortunately supports only voluntary reduction programs.
9.The issue of global warming affects nature, people, and the economy. To some people,
global warming is not of their concern because they feel it does not affect them. Although they may not realize it, global warming affects everyone, especially the future generations.
Scientists mathematically simulate the globe’s weather systems. Their complex equations, called general circulation models (GCMs), are so complex and involve countless elements that they can take days to solve. Environmentalists verify that the hazardous combination of flooding and drought will significantly increase within the next century. The standard sea level has been rising annually for a while now. Some say that if the earth continues on the path it is on, then 95% of the Great Barrier Reef will disappear by 2075. They calculate that the glaciers in Glacier National Park could melt by 2030, and 37% of all species could be extinct by 2050.
10.Scientists directly link disease to global warming. Exposure to various climate or animal
related diseases will increase in number and possibly brutality. Experts agree that skin cancer’s rapid rate of increase could be caused by the holes in the ozone layer. As these holes grow in size and number, the quantity of patients will also increase. Aside from natural and health issues, the world’s economy is also at risk. Ross Gelbspan, author of Boiling Point, a book about Earth’s climate change from global warming, spoke about his book to the public in 2004 stating, “Climate issues will eventually tear holes in the global economy.” Research can show that if current weather patterns continue, the cost of insurance will increase drastically over the next few years. Gelbspan is one of many authors and scientists who look into the future to warn people what is to come;
unfortunately, most people do not listen.
11.When people are trying to get others involved in the cause, a common problem that arises
is the lack of motivation. Many people do not realize that if they can slow the rapid warming process, then there will be more time to develop alternate energy sources, such as nuclear fusion. Holland and Germany, along with several small countries, have recognized this possibility and have committed to an 80% reduction of all greenhouse gas emissions. If the United States would get involved in a program such as this, then the greenhouse effect would occur much slower than it does today. The world, especially America, needs to take action now. Stephen H. Schneider of the National Center of Atmospheric Research (NCRA) once stated, “By the time we find the greenhouse warming had damaged earth’s ability to feed its people, it will be too late to do much about it.”
12.In conclusion, the world needs to put forth a stronger effort to prevent global warming; the
greenhouse gasses suffocate the earth more each day. If countries make a greater effort to slow global warming, the world’s predestination may not be reached until many years later. Individually, people can recycle, use fuel-efficient cars, carpool, and simply raise awareness. As said by Elmer Robinson, the director of Mauna Loa Observatory had once said while speaking of global warming, “The true enemy is us.”
Text 12 (p131-134) How Radiation Threatens Health
As worries grow over radiation leaks at Fukushima, is it possible to gauge the immediate and lasting health effects of radiation exposure? Here's the science behind radiation sickness and other threats facing Japan
By Nina Bai | March 15, 2011 1.The developing crisis at the Fukushima Daiichi nuclear power plant in the wake of the
March 11 earthquake and tsunami has raised concerns over the health effects of radiation exposure: What is a "dangerous" level of radiation? How does radiation damage health?
What are the consequences of acute and long-term low-dose radiation?
2.Though radioactive steam has been released to reduce pressure within the wrecked
complex's reactors and there has been additional radiation leakage from the three explosions there, the resulting spikes in radiation levels have not been sustained. The highest radiation level reported thus far was a pulse of 400 millisieverts per hour at reactor No. 3, measured at 10:22 A.M. local time March 15. (A sievert is a unit of ionizing radiation equal to 100 rems; a rem is a dosage unit of x-ray and gamma-ray radiation exposure.) The level of radiation decreases dramatically as distance from the site increases.
Radiation levels in Tokyo, about 220 kilometers to the southwest, have been reported to be only slightly above normal.
3."We are nowhere near levels where people should be worried," says Susan M. Langhorst,
a health physicist and the radiation safety officer at Washington University in Saint Louis.
4.According to Abel Gonzalez, vice chairman of the International Commission on
Radiological Protection who studied the 1986 Chernobyl disaster, current information coming from Japan about levels of radiation leakage are incomplete at best and speculations about "worst-case scenarios" are as of yet irrelevant.
5.The health effects caused by radiation exposure depend on its level, type and duration.
Radiation level:
6.The average person is exposed to 2 to 3 millisieverts of background radiation per year
from a combination of cosmic radiation and emissions from building materials and natural radioactive substances in the environment.
7.The U.S. Nuclear Regulatory Commission recommends that beyond this background level,
the public limit their exposure to less than an additional one millisievert per year. The U.S.
limit for radiation workers is 50 millisieverts annually, although few workers are exposed to anything approaching that amount. For patients undergoing medical radiation there is no strict exposure limit—it is the responsibility of medical professionals to weigh the risks and benefits of radiation used in diagnostics and treatment, according to Langhorst. A single CT scan, for example, can expose a patient to more than one millisievert.
8.Radiation sickness (or acute radiation syndrome) usually sets in after a whole-body dose
of three sieverts—3,000 times the recommended public dose limit per year, Langhorst says. The first symptoms of radiation sickness—nausea, vomiting, and diarrhea—can appear within minutes or in days, according to the U.S. Centers for Disease Control and Prevention. A period of serious illness, including appetite loss, fatigue, fever, gastrointestinal problems, and possible seizures or coma, may follow and last from hours to months.
Radiation type:
9.Of concern in the current situation is ionizing radiation, which is produced by
spontaneously decaying heavy isotopes, such as iodine 131 and cesium 137. (Isotopes are species of the same element, albeit with different numbers of neutrons and hence different atomic masses.) This type of radiation has sufficient energy to ionize atoms
(usually creating a positive charge by knocking out electrons), thereby giving them the chemical potential to react deleteriously with the atoms and molecules of living tissues. 10.Ionizing radiation takes different forms: In gamma and x-ray radiation atoms release
energetic light particles that are powerful enough to penetrate the body. Alpha and beta particle radiation is lower energy and can often be blocked by just a sheet of paper. If radioactive material is ingested or inhaled into the body, however, it is actually the lower energy alpha and beta radiation that becomes the more dangerous. That's because a large portion of gamma and x-ray radiation will pass directly through the body without interacting with the tissue (considering that at the atomic level, the body is mostly empty space), whereas alpha and beta radiation, unable to penetrate tissue, will expend all their energy by colliding with the atoms in the body and likely cause more damage.
11.In the Fukushima situation, the radioactive isotopes detected, iodine 131 and cesium 137,
emit both gamma and beta radiation. These radioactive elements are by-products of the fission reaction that generates power in the nuclear plants.
12.The Japanese government has evacuated 180,000 people from within a 20-kilometer
radius of the Fukushima Daiichi complex. They are urging people within 30 kilometers of the plant to remain indoors, close all windows, and to change clothes and wash exposed skin after going outside. These measures are mainly aimed at reducing the potential for inhaling or ingesting beta-emitting radioactive material.
Exposure time:
13. A very high single dose of radiation (acquired within minutes can be more harmful than the
same dosage accumulated over time. According to the World Nuclear Association, a single one-sievert dose is likely to cause temporary radiation sickness and lower white blood cell count, but is not fatal. One five-sievert dose would likely kill half of those exposed within a month. At 10 sieverts, death occurs within a few weeks.
14.The effects of long-term, low-dose radiation are much more difficult to gauge. DNA
damage from ionizing radiation can cause mutations that lead to cancer, especially in tissues with high rates of cell division, such as the gastrointestinal tract, reproductive cells and bone marrow. But the increase in cancer risk is so small as to be difficult to determine without studying a very large exposed population of people. As an example, according to Langhorst, 10,000 people exposed to a 0.01-sievert whole-body dose of radiation would potentially increase the total number of cancers in that population by eight. The normal prevalence of cancer, however, would predict 2,000 to 3,300 cancer cases in a population of 10,000, so "how do you see eight excess cancers?" Langhorst asks.
Chernobyl's lessons:
15.According to Gonzalez, some of the emergency workers at Chernobyl received several
sieverts of radiation, and many were working "basically naked" due to the heat, allowing contaminated powder to be absorbed through their skin. In comparison, the Japanese workers are most likely very well-equipped and protected at least from direct skin doses.
16.The Tokyo Electric Power Co. (TEPCO), the plant's owners, has evacuated most of its
workers, but 50 remain at the site to pump cooling seawater into the reactors and prevent more explosions. These workers are likely exposing themselves to high levels of radiation and braving significant health risks. "As a matter of precaution, I would limit the workers' exposure to 0.1 sievert and I would rotate them," Gonzalez says. The workers should be wearing personal detectors that calculate both the rate and total dose of radiation and that set off alarms when maximum doses are reached. "If the dose of the workers start to approach one sievert then the situation is serious," he says.
17.The thousands of children who became sick in the aftermath of the Chernobyl disaster
were not harmed from direct radiation or even from inhalation of radioactive particles, but from drinking milk contaminated with iodine 131. The isotope, released by the Chernobyl
explosion, had contaminated the grass on which cows fed, and the radioactive substance accumulated in cows' milk. Parents, unaware of the danger, served contaminated milk to their children. "Certainly this will not happen in Japan," Gonzalez says.
18.When it comes to radiation exposure, professionals who frequently work with radioactive
materials, whether in a hospital or a nuclear power plant, abide by the ALARA principle: "as low as reasonably achievable". Radiation exposure limits are conservatively set well below the levels known to induce radiation sickness or suspected of causing long-term health effects. Temporary exposure to dosages many times these limits, however, is not necessarily dangerous.
19.News of the U.S. Navy repositioning its warships upwind of the reactor site, the
distribution of potassium iodide pills by the Japanese government, and images of officials in hazmat suits using Geiger counters to measure radiation levels among babies may stoke the public's fears—but, for now, these measures are ALARA in action, or "good extra precautions," Gonzalez says. The idea here is to always err on the side of caution.
Text 15 (p186-188) Genetically Modified Foods – Feed the World?
This article examines the premise that Genetically Engineered Foods (also known as genetically modified foods; GMOs; GE foods; Frankenfoods; and so on) are the answer to ending world hunger. I feel that asking if GE foods will feed the world is at best an illogical primary question. Even more so, the question itself is a tactic meant to divert public attention from the real problems — inequality, discrimination, selfish leaders, war, flooding and drought, snow and rain, extreme temperatures and more. The diversions are made possible by political contributions, and lobbyists and media consultants hired by the ag bio tech industry, as well as their gifts and contracts to academia, which is presently in the dark ages with respect to honesty. No sector is without fault. And it is far easier to list the innocent than the guilty.
Most biotech industry studies and publications are highly visible forms of dis information that impact public opinion by both confusing the issues and intentionally providing false information that put GE foods in a favorable light. The intent of the massive, lobbying, public outreach, and advertising expenditures has been to rocket the proliferation of GE foods throughout the world before anyone was aware of the consequences. And indeed, nobody can predict the consequences because there is no precedent in the history of life on earth.
Section A Genetically Modified Food: How Did We Get Here?
By Paul Diehl
Biotech/Biomedical Expert
Genetically Modified Organisms (GMOs)
1.In the early 1970s, ways were discovered to move genes for antibiotic resistance from one
type of bacteria to another. The bacteria that received the gene, then became resistant to the antibiotic too.
2.This technology expanded to enable gene manipulation, not just in bacteria, but in plants
and animals which are biologically much more complicated. As a result, genes that confer desirable characteristics, such as resistant to pesticides, immunity to viral diseases, or advantageous rates of growth can be inserted directly into a plant's or animal's DNA.
3.This gene insertion produces a genetically modified organism (GMO) with a specific
desired trait.
The First GM Food
4.The first genetically modified (GM) food sold was Flavr-Savr tomatoes, developed in the
early 1990s by Calgene, Inc. The company was bought by Monsanto soon after the
tomatoes were approved for sale. These tomatoes were engineered to suppress the polygalacturonase gene to delay how quickly they would soften after ripening.
5.Flavr Savr Tomatoes could be picked riper and kept longer than other varieties. However,
to select the DNA that suppressed the polygalacturonase gene in the tomato, the researchers used a second gene that enables bacteria to be resistant to the antibiotic kanamycin. Flavr Savr Tomatoes, then, expressed this bacterial kanamycin resistance gene.
6.The slow softening of the tomatoes reduced the processing costs of making tomato
products, like tomato paste, so they were used to make low-cost versions of canned tomato products that were sold in supermarkets in the Western US and United Kingdom.
7.In 1998 after a UK scientist, Arpad Pusztai, expressed concern about GM foods on a
British TV program, sales declined dramatically. Flavr Savr Tomato products went off the market in 1999.
The Engineered Papaya
8. A more recent example of an engineered fruit is the Rainbow Papaya. In the 1990s, the
ringspot virus reduced Hawaiian papaya production by 40%. In response, Dr. Dennis Gonsalves, then at the University of Hawaii, engineered a papaya strain to make one of the ringspot virus genes (a virus coat protein) which made the papaya plant resistant to viral infection. The concept is similar to a vaccination.
9.Contrary to the perception of "big agriculture" pushing GM crops on the market, the
Rainbow Papaya seeds were initially distributed free of charge and now are sold at cost by the non-profit Hawaii Papaya Industry Association. The Rainbow Papaya is the only GM fruit currently sold (except for tomatoes if you consider them a fruit).
Resistance to Ringspot Virus Was Only the First Step
10.While the gene-altered Rainbow Papaya saved Hawaiian papaya agriculture, the fruit's
commercial success has been limited since a large part of the market for papayas is international. For example, Hawaiian papaya sales to Japan were $15 million in 1996, but only $1 million in 2010. Getting the Rainbow Papaya approved for sale outside the US has been a huge hurdle to its commercial success and true recovery of the Hawaiian papaya industry.
11.After more than ten years of lobbying, Japan finally approved sales of the Rainbow
Papaya at the end of 2011, enabling Hawaii an opportunity to recapture its lost papaya market. Since the Rainbow Papaya will be labeled as GM food, however, it still remains to be seen how well the fresh tasty gene-altered fruit will overcome popular concern about GM food.
Grains and Seeds: The Real GMO Success
12.Although the availability of genetically modified whole foods is somewhat sparse,
processed foods that include GM products have become a major commodities over the past dozen years. The majority of approved genetically engineered food are major industrial crops such as corn, soy, and cotton (cottonseed oil is used in processed foods).
In 2011, 160 million hectacres of GM crops were grown, 90% of which was in the US, Brazil, Argentina, India, and Canada. That's more than 10% of global crop land.
Approximately 82% of cotton, 75% of soybeans, 32% of corn, and 26% of canola are genetically engineered.
13.While much of the GM crops go to animal feed and fuel, GMOs have now become
common in groceries the Western hemisphere and India. Estimates are that about 70% of processed food sold in the US and 60% of processed food sold in Canada contains genetically modified plants, most from GM soybeans and corn. In contrast, only about 5% of processed on European store shelves contain GMOs.
What about GM Animals?
14.Genetically modified transgenic animals are commonly made and used in research. For
example, mouse models with extensive genetic engineering are a standard tool for drug discovery and development. However, so far, no GM animals have been introduced into
the food market.
15.The dearth of GM animal food may soon change, though, if AquAdvantage Salmon is
approved. AquAdvantage Salmon is Atlantic salmon with an additional unregulated Chinook salmon growth hormone gene inserted in its DNA. This gene from the faster growing Chinook salmon allows the AguAdvantage Salmon to grow larger more quickly than its natural cousins.
16.In Sept 2010, a review from the Veterinary Medicine Committee of the FDA that, "a large
number of test results established similarities and equivalence between AquAdvantage Salmon and Atlantic salmon" with regard to food safety. However, while final approval for the salmon was expected within a few months after this review, it is still pending almost two years later.
No Easy Answers to GMOs
17.Are GMOs a dangerous and unnatural aberration of our food sources or a natural
extension of modern technology to improve our food supply? Of course, it depends on who you ask. GM plants, at least, have rapidly become a significant and expanding part of the global food market.
18.Genetic manipulation through crossbreeding has been done for thousands of years to
produce the agricultural revolution that resulted in domesticated corn and wheat, grotesque chickens, and hundreds of varieties of apples. These techniques have produced a global population of 7 billion. Today, genetic engineering may be the most effective way to further improve food production to meet the challenges of a growing global population. Will direct manipulation of DNA by genetic engineering herald next step in crop improvement and food development to meet the future challenges of feeding the world, or is it a risky endeavor that could lead to severe global health consequences?
Section B Can Genetically Modified Food Feed the World?
1.One of the main benefits that advocates of genetically modified (GM) food have promoted
is its ability to help alleviate world hunger. In 2011, 160 million hectares of biotech crops were grown—that's 10% of earth's arable land and it was an 8% increase than the previous year. The growth of biotech crops is the fastest growth segment in agriculture.
While much of these crops are used for animal feed and biofuel, much of it also makes its way directly into a majority of processed foods sold in America and Asia.
2.You can find more information about how the GM food market developed in the related,
"Genetically Modified Food: How Did We Get Here?" article. However, despite all the commercial success of GM crops, have they made a significant impact on world hunger?
What's driving the GM Food Revolution?
3.The first GM food, the Flavr-Savr Tomato, reduced the cost to produce canned tomato
products about 20% and numerous studies have shown an economic benefit for farmers planting GM crops. Even livestock can be raised less expensively, using feed made from GM crops as evidenced by the recent change in EU policy to help struggling farmers. Also, faster growth rates resulting in cheaper fish production is the main benefit touted for the AquaBounty salmon that may become the first GM animal approved to be sold as food. 4.It's clear genetically engineered traits that make plants and animals more resistant to
disease, stay ripe longer, and grow more robustly in a variety of conditions are effective in reducing costs and providing economic benefits to food producers.
5.Of course, the companies, such as Monsanto, Syngenta, and Aventis, that produce GM
crops also rake in profits, and opportunities for smaller start-up biotech companies, such as a AquaBounty and Artic Apples abound. Clearly, there are good economic incentives for GM food development and production that drive development of these genetically modified organisms (GMOs).
Are GM Crops Helping to Feed More People?
6.Since they are cheaper to grow, increase yields, and extend the time food remains edible,
it seems reasonable that GM plants should provide more food to a hungry world. However, it is not clear this is panning out as may have been naively anticipated several years ago.
The countries that could benefit most from genetic engineering have actually benefited the least. A 2008 Science article, "Agriculture at a Crossroads" noted that, "The potential of GM crops to serve the needs of the subsistence farmer is recognized, but this potential remains unfulfilled. No conclusive evidence was found that GM crops have so far offered solutions to the broader socioeconomic dilemmas faced by developing countries."
Politics v. Research and Distribution
7.Much of the inability of GM technology to provide relief for the poorest nations seems to
have less to do with the technology and more with social and political issues. Many of the poorest countries most strongly affected by famine, such as many Africa nations, have set up onerous regulations that prevent the growth and import of GM food and crops. Much of this resistance seems to be prompted by groups such as the African Center for Biosafety and SAFeAGE, and also from international relationships with Europe which has tight restrictions on GM food. In addition, and partially as a result of the political and social situation, groups, such as HarvestPlus, that focus on research and development crops and farming techniques to address third world hunger specifically avoid genetic engineering as a method to improve plants.
8.Anti-GM sentiment, though, is not the only reason it has failed to benefit the poorest
nations. From the commercial side, major crop development companies use genetic engineering primarily to improve large cash crops with the most potential for profits, such as corn, cotton, soy, and wheat with. Little investment is put into crops, such as cassava, sorghum, millet, etc. which are more relevant for cultivation in poor nations. The economic incentive to develop the sort of GM crops that would help small poor farmers in third world nations is small since the financial returns would be modest. Of course, anti-GM sentiment does nothing to ameliorate this bias.
Can Genetic Engineering Help Solve World Hunger?
9.OK, so let's just say it, the main driver pushing the development of GM crops is profits. Big
agricultural companies, farmers, and food producers all want to make more money. These entities have benefited most from GM crops and this incentive has certainly been helping move forward the development of the technology. Some might even say it is way it is supposed to work—capitalism driving innovation. That's a different debate, though, and profit-driven efforts certainly don't negate the possibility that the technology can also be applied to benefit society at large by reducing world hunger. However, it also doesn't mean it will.
10.In fact, though, genetic engineering is a powerful tool for improving food production. There
is no faster way to produce animals and plants with specific beneficial traits and, as we learn more about the genetics, many more modifications will become possible. While this may scare many, the potential is also enormous and clearly could play a role to improve the situation for the poorest in the world.
11.Frankly, at this point, there is no question whether to apply genetic engineering toward
improving crops for food consumption. Genetic modification is already part of the crop improvement tool box. The real question is if, in addition to helping make many wealthier in the industrialized work, this advanced technology provides part of the solution to help improve the lot of the poorest regions of the world. Applying this technology to safely and effectively solve the problems of third world hunger, though, would require reasonable engagement and coordination from a variety political and social groups, and that, may be too much to hope for.
经典英语励志句子 本文是关于经典英语励志句子，仅供参考，希望对您有所帮助，感谢阅读。 经典英语励志句子(精选篇) 1、事常与人违，事总在人为。 Things often contrary to people, things always in the. 2、xx干戚，猛志固常在。 Energy-saving, Meng Chi solid in. 3、恨别人，痛苦的却是自己。 Hate other people, the pain is their own. 4、疾风知劲草，板荡识诚臣。 Wind Supergrass, is general Cheng chen. 5、心有多大，舞台就有多大。 The stage extends as far as the heart goes。 6、只有想不到，没有做不到。 Only think, can not do. 7、把握现在、就是创造未来。 Grasp now, is to create the future. 8、岁寒，然后知xx之后凋也。 Only in cold winter does one know that the pine and the cypress arethe last to shed their leaves。 9、人生最大的失败，就是放弃。
The biggest failure in life is to give up. 10、我们可以失望，但不能盲目。 We can be disappointed, but not blind. 经典英语励志句子(热门篇) 1、用勤奋实现梦想，用xx成就人生。 With diligence dream，with achievement life wisdom。2、经常是最后一把钥匙打开了门。 Is often the last key to open the door。 3、时间是宝贵的，抓住了时间就抓住了成功。 Time is precious，grasp the time。 4、除了放弃尝试以外没有失败!Inadditiontogiveuptryingnofailure! 5、世界上只有想不通的人，没有走不通的路。 The world only think impassability，did not go。 6、信仰是伟大的情感，一种创造力量。 Faith is a great emotion，a kind of creative power。 7、没有不合格的学生，只有不合格的家长。 There is no unqualified students，only unqualified parents。 8、忙于采集的蜜蜂，无暇在人前高谈阔论。 Bees are busy collecting，too busy to talk in front of people。 9、网络事业创造了富裕，又延续了平等。 Network enterprise to create a rich and lasted for equality。
文献摘要翻译： 文摘1： Particle Formation during Anatase Precipitation of Seeded Titanyl Sulfate Solution Sekhar Sathyamoorthy,? Geoff D. Moggridge,*,? and Michael J. Hounslow? Department of Chemical Engineering, Cambridge University, Pembroke Street, Cambridge CB2 3RA, U.K,., and Department of Chemical and Process Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K. Received July 14, 2000 ABSTRACT: The formation of anatase particles in the Sulfate Process is an important step in the production of white pigment. This paper investigates the mechanisms behind particle formation during anatase precipitation from seeded concentrated titanyl sulfate solution. The process of particle formation was found to be highly dependent on the volume of seeds inoculated. Secondary nucleation played an important role in the production of anatase crystals and, ultimately, overall yield of the precipitation step. Anatase crystals were found to be between 4 and 8 nm from powder diffraction line broadening calculations. Nucleation also influences the structure and size of primary agglomerates consisting of a number of crystals. The final anatase particles recovered from the precipitation are in the form of 1-2μm aggregates, comprised of polycrystalline primary agglomerates. 摘自Crystal Growth & Design,2001,1(2):123~129 文摘2： Controlling Particle Size During Anatase Precipitation Sekhar Sathyamoorthy and Geoff D. Moggridge Dept. of Chemical Engineering, Cambridge University, Pembroke Street, Cambridge CB2 3RA, U.K. Michael J. Hounslow Dept. of Chemical and Process Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, U.K. 摘自：AIChE Journal ，2001 Vol. 47, No. 9 Titanium dioxide particles in the form of anatase are precipitated from concentrated titanyl sulfate solution in the sulfate process, which are then recovered by a filtration process downstream of the precipitation stage. A pre vious study by Sathyamoorthy et al. showed that the final anatase particles are aggregates(1-2 μm)consisting of numerous crystals(7 ~ 8 nm)arranged in primary agglomerates(60 ~ 100 nm). Pigment quality is determined by crystal and primary agglomerate size. One way of improving filtration rate is by the formation of larger aggregates, while maintaining the crystal and primary agglomerate size at optimum values. In a new seeding procedure proposed, the controlled inoculation of seeds used in industry is combined with a new type of seed (Large Seeds). The new seeding procedure has the
摘要（Abstract） 摘要(Abstract) 也成为内容提要，通常在学士论文中都必须附有摘要，其位置应放在论文的正文之前，对整个论文内容的概述。无论对专业读者还是对非专业读者而言，摘要都是一个非常重要的文件。 摘要如果和论文一起发表，则被称为一次性出版物摘要，主要用于帮助读者评价文章内容及其潜在作用，使读者不必阅读全文就可以了解论文的内容。除此之外，摘要也可以被单独收入文摘机构出版的摘要期刊如：生物学文摘（Biological Abstract）、化学文摘（Chemical Abstract）等、称为二次性出版物摘要。此类脱离论文独立成篇的摘要主要用于方便读者检索文献、收集信息，帮助研究者寻找新的研究领域。 一．摘要的定义 摘要的英文术语：有两个词汇，一个是abstract, 一个是summary. 根据美国国家标准学会（American National Standard Institute）于1971年通过并颁布的《美国国家文摘写作标准》（American National Standard for Writing Abstracts）规定，Abstract 不应与summary 混同。 Abstract 对一篇论文的主要内容以精炼的文字进行高度概括，使读者不必阅读全文即可了解论文内容，或者让读者对即将阅读的文章有思想准备，或者让读者判断是否有通读全文的必要。文中只对论文信息进行浓缩，而不加主观评论或解释，可以脱离原文而独立成篇。字数通常在100~150个词左右，更确切地说，约为原文长度的1% ~ 5%（有的杂志规定摘要平均为全文的3% ~ 5%）。现在越来越多的用法是abstract. 尤其是放在索引资料中一律要用abstract 这个术语，在论文的题目下也通常要用这个词。 Summary (概要) 与abstract 无明显差别。严格地说，summary 一般附在论文的后面，对论文的主要结论和成果进行再叙述。其前提是读者已经通读过全文，通过summary 来巩固论文的主要论点和成果。在某些论文中，用summary 取代正文中的conclusion 部分。Summary 是论文的“缩影”，可以概括论文的全部内容，只是在删繁就简上下功夫，字数长短不一，少则两三句话，多则500个单词甚至更长。美国的一些高等学校规定，硕士论文提要（summary）以250词左右为宜，而博士论文题要以350词左右为宜。国际会议论文的提要一般规定为300 ~ 500 词或1000 个印刷符号。 至于究竟要采用什么形式，要根据征稿而定。一般说来，国际学术会议论文及要求按Summary 方式来写摘要，而正式出版发行的刊物要修不尽一致。对于个别论文还见有前面为Abstract, 结尾又有一个Summary , 这多半是由于文章过长，内容有多，后面的Summary 相当于该文的缩写。 二．摘要的种类 摘要分为两类，一类是说明性摘要（Descriptive/ Indicative Abstract），一类是资料性（Informative Abstract）摘要。 1.说明性摘要（Descriptive / Indicative Abstract） 如同迈克尔.艾利（Michael Alley）所说，“一篇说明性摘要是段落形式的目录，使读者手中的一份简要地图。”从这句话中可以清楚地了解说明性摘要的作用。说明性摘要指向读者指出论文的主要议题是什么，不涉及具体的研究方法和结果，但无法给读者提供更多的详细信息。它一般是用于综述性文章，也用于讨论、评论性文章，尤以介绍某学科近期发展动态的论文居多，常出现“…is studied”、“…is discussed”字样。时态多用现在时或现在完成时。其篇幅也较短，大多在100 ~ 150 字之间。以下是一篇说明性摘要的样例。 Ten widespread diseases that are hazards in isolated construction camps can be prevented by removing or destroying the breeding places of flies, mosquitoes and rats, and by killing their adult forms. 由于说明性摘要仅限于陈述论文的主要论题且篇幅较小，主要用于评述性的论文。 2.资料性摘要（Informative Abstract） 资料性摘要的优点是比说明性摘要能提供多的多的信息，它应该尽量完整和准确地体现原文的具体内容，特别强调指出研究的方法和结果、结论等。其篇幅较长，大多在150 ~250 字之间。根据原文长度，也有多达500字的。通常，这类的摘要反映了论文的基本面貌，能够代替阅读论文全文。
有志者事竟成：经典励志英语100句.txt38当乌云布满天空时，悲观的人看到的是“黑云压城城欲摧”，乐观的人看到的是“甲光向日金鳞开”。无论处在什么厄运中，只要保持乐观的心态，总能找到这样奇特的草莓。 1.有志者，事竟成.Nothing is impossible to a willing heart./Where there is a will there is a way。 2.千里之行，始于足下.The longest journey begins with the first step。 3.积少成多.Every little helps。 4.满招损，谦受益.Pride hurts,modesty benefits。 5.世上唯有贫穷可以不劳而获.Nothing is to be got without pain but poverty。 6.伟业非一日之功/冰冻三尺非一日之寒.Rome was not built in a day。 7.一寸光阴一寸金，寸今难买寸光阴.Lost years are worse than lost dollars。 8.自助者天助.God helps those who help themselves。 9.欲速则不达.More haste,less speed。 10.台上一分钟，台下十年功.One minute on the stage needs ten years practice off stage。 11.好的开端是成功的一半.Well begun is half done。 12.酒好不怕巷子深.Good wine needs no bush。 13.成功源于勤奋.Industry is the parent of success。 14.英雄所见略同.Great minds think alike。 15.熟能生巧.Practice makes perfect。 16.静水流深.Still waters run deep。 17.滴水穿石.Little stone fell great oaks。 18.前事不忘，后事之师.The remembrance of the past is the teacher of the future。 19.君子之交淡如水.A hedge between keeps friendship green。 20.机不可失，时不再来.Take time while time is,for time will away。
励志的英语经典语句（二十） 191、 Take a chance! All life is a chance. The man who goes farthest is generally th e one who is willing to do and dare. 去冒险吧！人生就是一场冒险，走得最远的通常都是愿意且勇于冒险的人。Dale Carnegie 192、Like a song, a lot of time not because of love, just a way to miss a person.喜欢一首歌，很多时候不是因为喜欢，只是借一种方式去怀念一个人。 193、In my heart, accompany and understand, is more important than love. 在我心中，陪伴与懂得，比爱情更加重要。 194、The most beautiful thing is not keep time, but retain memories. The real power, not to forgive others, but let themselves. 最美的事不是留住时光，而是留住记忆。真正的强大，不是原谅别人，而是放过自己。 195、Sometimes，to get what you want the most, you have to do what you want the least.有时候为了得到你最想要的，你不得不做你最不想做的。 196、Is there such a person, you countless times about her to give up, but in the end still reluctant. 有没有这么一个人，你无数次说着要放弃，但终究还是舍不得。 197、Nobody notices your sorrow, your pain, but everyone notices your mistakes.没人会注意你的苦痛，但所有人都会关注你的错漏。 198、Every day is a new beginning. Treat it that way. Stay away from what might have been, and look at what can be. ——每一天都是一个崭新的开始，当如此对待。不要再纠结于过去，想想现在能做点什么吧。 199、Life is short, so smile while you still have teeth. ——人生太短，所以笑吧，趁你现在还有牙齿时。 200、Flowers open in the dust, more brilliant. Smile stands in the dust, more calmly.——开在尘埃里的花，更灿烂。伫立在尘埃里微笑，更从容。
房地产企业安全氛围对安全行为的影响研究 摘要：为了探讨房地产企业安全氛围对员工安全行为的影响及其作用机制。研究采用问卷调查研究的方法，调查对象为某房地产企业的200名员工。结果表明，安全氛围对安全行为有显著的正向影响。其中，安全氛围中的“工作环境”和“安全意识”维度对员工安全行为有着直接的显著正向影响；“管理层承诺”维度对员工安全行为没有直接的显著的影响，但是管理层承诺通过工作环境和安全意识的完全中介作用于员工安全行为。 关键词：管理层承诺；安全意识；安全行为；结构方程模型 The Effect of Safety Climate on Safety Behavior in Real Esate Enterprise Abstract：In order todiscuss the influence and mechanism between the safety atmosphere and the staff’s safety behavior of the real estate enterprise.The study uses questionnaire survey research method,the objects of the investigation are 200 employees in one real estate enterprise.The results indicate that safety climate is positively related to safety behavior.The “work environment” dimension and “safety consciousness” dimension have direct and positive influence on safety behavior. The “management commitment ” dimention has no direct influence on safety behavior,but“management commitment”affects safety behavior positively through work environment and safety consciousness. Key words:management commitment; safety consciousness; safety behavior; structural equation model
写好英文论文摘要的七个要素 英文论文摘要是英文论文最开始的部分，其重要性可想而知。它就像是一篇论文的眼睛，如何用一双顾盼神飞的眼睛赢得评审老师的心？ 1. 英文摘要是什么？ ABSTRACT，是用最为浓缩的语言将你论文的核心内容表述出来。不需要你用华丽的语言去描述！只留下普通、平实的内容。 2. 如何写英文摘要？ 可以按照论文的逻辑结构撰写摘要，如概述、目的、方法、结果、结论、展望的顺序。 概述(30词左右)：用最简洁的语言概括论文内容。例如：This paper is…或This study focuses on… 目的(30词左右)：用To…就可以了，没有必要使用in order to 或者for the purpose of 等较长的表述。 方法(50词左右)：尽可能具体地说明操作的步骤，其中注意时态的使用。常用的词汇有：test, study, investigate, examine, analyze, measure, application 等。 结果(50词左右)：直入主题地摆出结果，如This paper shows…或The results are… 结论(60词左右)：删去类似于“The result of the study showed that…”的赘语，逐条罗列出结论。 展望(20词左右)：指出研究对未来的意义，如This paper is of great significance in…或指出不足。 3. 常用什么语态？ 规范的学术文章通常采用被动语态，突出信息。但由于主动语态的表述更为清楚，现在有些地方也要求采用主动语态。 4. 常用什么人称？ 最好不要出现I，we等第一人称代词，而是使用第三人称，如the author等。 5. 一般有多少字？ 一般情况下用一段的篇幅完成英文摘要，特殊情况可以分成两到三段，但最好不要超过三段。长度一般为200字到300字之间。 6. 不能有的东西？ 不常见的术语，插图，表格，数学公式，化学方程式，中文标点，过多的形容词，无关的背景资料，自我评价等。 7. 常用什么时态？ 摘要的时态以一般现在时为主，表示一种存在于自然界的客观规律。在特殊的情况下可以使用一般过去时或现在完成时，用来表明一定范围内的结论或是某一过程的延续性。描述具体的动作时通常用一般过去时，总结主要的结果时通常用一般现在时。 注意：用paper 做主语来描述论文概况时后面常用一般现在时：This paper aims to focus on…而采用study 来描述相同的内容时则常用一般过去时：This study investigated…
Without any previous notice, a documentary dominated headlines and social websites over the weekend. 没有一点毫无征兆，上周的头条和热门网站就被一部纪录片刷了屏。 Under the Dome, a 103-minute documentary self-funded by former news anchor Chai Jing, was released on video-sharing websites in China on Feb 28. It has rapidly pushed the public awareness about air pollution and encouraged people to join in efforts to make a difference. 这部103分钟的纪录片名为《穹顶之下》，于2月28日登上中国各大视频网站，它 是由前央视新闻调查记者柴静自费拍摄制作。影片一经发布就迅速引起公众对于空气 污染的关注，也鼓励了人们要有所行动。 Chai, 39, said she started the work out of her “personal clashes” with smog after she gave birth to a daughter. “I sealed tight all the windows. I started every day by checking the air pollution index,” Chai said. Millions of other people are also doing the same. While they stop there, Chai goes deeper. “I don?t want to live in this way. I need to find out where the smog comes from and what on ea rth is going on.” 今年39岁的柴静在女儿出生后开始着手拍摄此片，称其为一个母亲和雾霾的“私人 恩怨”。她说：“我把所有的窗户都封起来。每天起床的第一件事就是查看当天的空 气污染指数。”其实，成千上百万人和她做着同样的事情，只不过他们止步于此，而 柴静做了更多，她说，“我不想这样活着。我想知道这些雾霾到底从哪儿来，到底发 生了什么？” Over a year, she investigated polluted sites to find the sources of smog, visited the US and the UK to learn about their anti-pollution experiences, and interviewed officials, scientists and the general public. 一年间，她深入污染地区调查雾霾的来源，远赴美国、英国了解治理空气污染的经验；官员、科学家以及普通百姓都出现在她的采访镜头之中。 Chai?s research reveals that the burning of coal and oil c ontributes to 60 percent of PM2.5 pollutants. She thus questions the country?s energy consumption habits in the film. 柴静调研发现，PM2.5主要来自煤与油的燃烧（占60%）。于是，她的这部记录片矛头直指我国能源消费习惯。
英语专业本科毕业论文论文摘要格式 中英文摘要对应，内容要基本保持一致；中文在前，英文在后。字数为300-500字左右。 1．中文摘要 ①首行居中打印论文中文标题（宋体四号加粗） ②下空一行居中打印“摘要”二字（宋体小四号加粗），字间空一字符。 ③“摘要”二字下空一行打印摘要内容（宋体小四号）。 ④摘要内容后下空一行打印“关键词”三字（宋体小四号加粗），其后接 着打印关键词（3－7个，宋体小四号），各关键词之间用逗号隔开，最 后一个关键词后不打标点符号。 2．英文摘要 ①首行居中打印论文英文标题（Times New Roman四号加粗） ②下空一行居中打印英文单词“Abstract”（Times New Roman小四号加粗）。 ③下空一行打印摘要内容（Times New Roman小四，1.5倍行距，两端对齐） ④摘要内容后下空一行打印“Key Words”（Times New Roman 小四 号加粗），其后接着打印关键词（3－7个关键词，Times New
Roman 小四号）。除了专有名词外，其他单词的首字母不大写。各关键 词之间用分号隔开，最后一个关键词后不打标点符号。 ⑤摘要正文各自然段首行空5个字符。 （空1 行） （空1行） Having such a After she relationship with she realizes her own faults and acquires self-knowledge of both moral faults and emotion. she comes to know that feelings can not should not force her own idea on beginning of Emma’s self -knowledge. （空1行） Key Words: Emma; characters; match-making; self-knowledge
经典励志英文短句 While there is life there is hope. 一息若存，希望不灭。 I am a slow walker,but I never walk backwards. (Abraham.Lincoln America) 我走得很慢，但是我从来不会后退。(亚伯拉罕.林肯美国) Never underestimate your power to change yourself! 永远不要低估你改变自我的水平! Nothing is impossible! 没有什么不可能! Nothing for nothing. 不费力气，一无所得。 The man who has made up his mind to win will never say "impossible ". (Bonaparte Napoleon ,French emperor ) 凡是决心取得胜利的人是从来不说“不可能的”。( 法国皇帝拿破仑. B.) The man who has made up his mind to win will never say "impossible ". (Bonaparte Napoleon ,French emperor ) 凡是决心取得胜利的人是从来不说“不可能的”。( 法国皇帝拿破仑. B.) I will greet this day with love in my heart. 我要用全身心的爱来迎接今天
Do what you say,say what you do 做你说过的，说你能做的 I can make it through the rain. I can stand up once again on my own. 我能够穿越云雨，也能够东山再起(Mariah Carey-through the rain) All things come to those who wait. 苍天不负有心人 Never, never, never, never give up (Winston Churchill) 永远不要、不要、不要、不要放弃。(英国首相丘吉尔) A man is not old as long as he is seeking something. A man is not old until regrets take the place of dreams. (J. Barrymore) 只要一个人还有追求，他就没有老。直到后悔取代了梦想，一个人才算老。(巴里摩尔) You have to believe in yourself . That's the secret of success.(Charles Chaplin , American actor ) 人必须相信自己，这是成功的秘诀。 (美国演员卓别林. C.) One's real value first lies in to what degree and what sense he set himself.(Einstein Germany) 一个人的真正价值首先决定于他在什么水准上和在什么意义上从自我解放出来。(爱因斯坦德国)
研究论文英文摘要翻译 【摘要】本文作者在多年从事学报论文摘要的撰写与翻译、审核与校对的工作中，发现我院科研论文作者提交的英文摘要撰写和翻译错误，有不少值得改善的地方。同时也提醒即将发表论文的作者，在撰写或翻译论文摘要时注意的一些理由。本文对我院英文论文的发表、摘要的撰写和英语翻译具有积极的指导。 【关键词】摘要翻译 【注】本论文受《具有军事特色的网络文化大学英语课程体系研究》科研项目支持。 （） 目前，科技论文与信息的国际交流日益频繁。但许多期刊数据库只免费提供摘要的阅读，许多国外读者只能阅读摘要来判断是否阅读全文。因此摘要的英文翻译对于论文的国际引用次数、检索率具有十分的。除非是在英语国家生活工作很长时间英语功底非常扎实，我院一般论文作者撰写摘要很大程度上是把已经写好的中文摘要翻译成英文，在撰写或翻译时有不少方面注意。 .摘要的英文翻译原则 英文摘要标题实词首字母要大写 汉语文章的标题不存在大小写之分，但有字体大小的不同。英语除了字体不同之外，还有大小写字母之分。，英文摘要的标题的实词要大写，非句首介词等虚词不大写。例如一篇论文标题为“基于静态舒适性分析的装甲车辆驾驶舱人机匹配研究”的文章英语译名为
“ ？鄄？蒺”（摘自年学报第期“基于静态舒适性分析的装甲车辆驾驶舱人机匹配研究”，作者：谢成林刘维平）。在此标题中除了两个介词“”之外，其它实词首字母大写。其次，复合词只需第一个单词首字母大写。仍以上述标题为例，复合形容词“？鄄”中只需将“”首字母“”大写，连字符后面的“”则不大写。再者，标题中较长（个字母以上）的虚词也要大写。如标题“ （非拆解发动机探伤）”中介词“”大写。此外，位于首位或末尾的虚词也大写。如：（装备采购原则研究）。 摘要标题翻译的名词化 摘要一般不是完整的句子，不含谓语动词。我院学报上见到的中文论文标题几乎较长的名词性结构或介词结构短语，很少看到完整的句子。因此在译成英文时，也大多以名词短语的形式出现，一般不包含谓语成分。比如，有篇论文标题为“履带车辆转向性能指标修正与实验研究”，就是一个以“研究”为核心词的偏正词组。其译文也是如此，只是英文中核心词的位置放到前面，如“ ”（摘自学报年“履带车辆转向性能指标修正与实验研究”，作者：宋海军高连华）。 .作者姓名的翻译要规范化 作者姓名的汉语拼音要规范 在科研论文的撰写、编辑中，经常见到姓名汉语拼音书写不够规范甚至错误的现象。根据国家颁布的《中国人名汉字拼音字母拼写法》（）的规定，姓名拼音可归纳为以下点。. 汉语姓名的拼音法以普通
摘要：关于百度知道中网友们关于英语论文摘要所提出来的热点话题，在此小编为大家总结了英语论文摘要的写法，英语论文摘要的格式参考，并附上范例一则，希望对大家的英语论文摘要写作有所帮助。 英语论文摘要怎么写英语论文摘要格式模板（附范例） 英语论文摘要 英语专业毕业论文摘要怎么写 英文论文摘要怎么写 怎么写好英语论文摘要 …… 这些都是百度知道中网友们提出来的热点话题，在此小编为大家总结了英语论文摘要的写法，英语论文摘要的格式参考，并附上范例一则，希望对大家的英语论文摘要写作有所帮助。 英语专业本科毕业论文论文摘要格式 中英文摘要对应，内容要基本保持一致；中文在前，英文在后。字数为300-500字左右。 1．中文摘要 ①首行居中打印论文中文标题（宋体四号加粗） ②下空一行居中打印“摘要”二字（宋体小四号加粗），字间空一字符。 ③“摘要”二字下空一行打印摘要内容（宋体小四号）。 ④摘要内容后下空一行打印“关键词”三字（宋体小四号加粗），其后接着打印关键词（3－7个，宋体小四号），各关键词之间用逗号隔开，最后一个关键词后不打标点符号。 2．英文摘要 ①首行居中打印论文英文标题（Times New Roman四号加粗） ②下空一行居中打印英文单词“Abstract”（Times New Roman小四号加粗）。 ③下空一行打印摘要内容（Times New Roman小四，倍行距，两端对齐） ④摘要内容后下空一行打印“Key Words”（ Times New Roman 小四号加粗），其后接着打印关键词（3－7个关键词，Times New Roman小四号）。除了专有名词外，其他单词的首字母不大写。各关键词之间用分号隔开，最后一个关键词后不打标点符号。 ⑤摘要正文各自然段首行空5个字符。 Self-Knowledge of Emma （空1行） Abstract （空1行） Emma lives in a quite simple environment. When she is a little child, her mother dies and she is spoiled by her father. Having such a background, Emma is dominant, aggressive and imaginative. After she experiences the two major affairs in her life----the relationship with Harriet and her
英语文摘句子合集 如果对英语学习毫无兴趣，那么是学不好的，如果迫切想要提高英语水平，一定要试着培养对英语学习的兴趣才能达到事半功倍的效果!今天小编在这给大家整理了英语文摘大全，接下来随着小编一起来看看吧! 英语文摘(一) 1、对于我来说，没有愿不愿意，只有应不应该。 Ready or not, for me, not only should. 2、天空没有了太阳，那向日葵如何仰望她的爱。 The sky without the sun, the sunflower how to look up to her love. 3、只要是个喜剧结局，过程你让我怎么哭都行。 As long as is a comedy ending, process you let I how cry will do. 4、停下来休息的时候，不要忘记别人还在奔跑。 Stopped to rest, dont forget people still running. 5、所谓的一见钟情，只是喜欢上你的外表罢了。 The so-called love at first sight, just like your appearance. 6、我相信只要踏踏实实的走，总会走出我的天。 I believe that as long as the steadfast walk, always out of my day.
7、又回到了原点，就从现在开始我的新生活吧。 Back to the origin, from now on, my new life. 8、对相爱的人来说，对方的心才是最好的房子。 For people who love each other, each others heart is the best house. 9、很多改变，不需要你自己说，别人会看得到。 A lot of change, dont need you say it, people will see. 10、你我曾经激荡的青春，是我今生最美的回忆。 You I used to agitate the youth, is I this life the most beautifulmemories. 11、男人多心，问东问西，女人多心，翻东翻西。 Man sweat, ask east asked west woman sweat, turn east to west. 12、爱到彼岸尽头，原来只是我一个人的独角戏。 Love in the end, the original is just my a persons monologue. 13、过错是暂时的遗憾，而错过则是永远的遗憾。 Fault is temporary regret, but miss is eternal regret. 14、人生太短，所以笑吧，趁你现在还有牙齿时。 Life is too short, so laugh, while you now have teeth. 15、没有过不去的坎，让自己跨越的姿势美一点。 No hard candy, just let yourself across posture beauty. 16、他种了情，情开了花，花结了果，铭记于心。
(一)大学生网络学习情况调查研究 摘要：本文基于大连市部分高校大学生网络学习情况的问卷调查所得数据,从多层次、多角度分析了大学生的网络学习现状与资源建设应用情况,就存在的一些问题提出了建议。 关键词：大学生网络学习调查 College Students' learning situation investigation and study Key words:College student Network Learning Investigation Abstract:This thesis based on Dalian university students learning situation survey data, from the multi-level, multi-angle analysis of universties students' learning situation and resource construction and application situations, raise some suggestions about existing problems. （二）北京地区小学阶段基于手机的移动教育发展与需求研究 摘要：移动教育将成为教育信息化深化发展的新方向,成为深入推进素质教育与课程改革的新的创新载体,对推进我国基础教育改革发展具有重要作用。本文从学生、教师、家长三个角度对小学阶段基于手机的移动教育进行研究,深入分析了基于手机的移动教育发展的阻碍因素与促进因素,进行移动教育需求研究,在此基础上,提出小学阶段基于手机的移动教育发展策略。 关键词：小学移动教育发展需求 The research about development and demand of education based on mobile phone in primary school of BJ Abstract:Mobile education will become the new direction of educational informatization deepen development, be of promoting quality education and curriculum reform in the new carrier of innovation has an important role in promoting China basic educational reform development. This article have a research based on primary atage mobile phone education from the students, teachers, parents of three angles, analysis the obstacle factors and promoting factors about mobile phone's mobile education development deeply, mobile education demand research,on this foundation,put forward primary school stage education development strategy based on mobile phone . Key words:Primary School Mobile Education Development Demand