首页>要闻>天下           天下         



2019年05月20日 01:19:17 | 作者:飞度技术医院大全 | 来源:新华社
At first, the Europeans relied heavily on local food supply by native people. But as they settled in, their farming practices began to shape the landscape of North America.期初,欧洲人十分依赖当地居民提供的本土食物。但是随着他们逐渐融入美洲大陆,他们的农业活动也开始改变着北美大陆的面貌。The plow allowed them to farm larger areas of land, helping to feed the expanding population. 使用犁,他们可以耕作大面积的土地,这样就能喂养迅速膨胀的人口。While this new type of agriculture robbed many animals of their habitat, others were to reap the benefits. 然而这样一种新型农业掠夺了很多动物的栖息地,而也有些动物成为这种农业的受益者。Birds such as grackles, cowbirds and red-winged blackbirds exploded in numbers, feeding off the waste remains of farming. These pest birds were aly common around small native farms in the east. Now large scale farming of crops such as corn, wheat and barley fuel(s) their numbers to epidemic proportions. 一些鸟儿的数量大范围增长,例如白头翁、燕八哥和红翅黑鹂,它们以一些剩余的、废弃的农作物为食。这些益鸟在东部当地人的农场中随处可见。目前,由于大面积种植玉米、小麦、大麦等粮食,这些鸟儿的数量更加大幅上涨。Despite these pests, North Americas agricultural kept on booming, becoming big business. Great sways of a once wild landscape have been turned over to farming. 不管这些动物,北美的农业都继续蓬勃发展着,并正逐渐成为最大的商业。大部分荒地被开垦以用于农耕。英文文本来自普特英语,译文属未经许可不得转载。201312/267213Science and technology科学技术Launching aircraft发射飞机Proof by induction让电磁感应来验In the future, airliners could be catapulted into the sky by electric motors将来,会用电动机将客机弹射到天空中 READERS of a certain age may remember Fireball XL5, a childrens television programme devised by Gerry Anderson about a spacecraft of that name.某个年龄段的读者可能还记得《雷霆机》这个儿童电视节目,这个节目是由格里安德森制作的,讲的是一艘叫做雷霆机的宇宙飞船的故事。Instead of taking off vertically, as real spacecraft do, Fireball XL5 sat on a rocket-propelled trolley that accelerated it horizontally to launch speed.与现实中的宇宙飞船垂直起飞不同,雷霆机是架在一个由火箭推动的滑车上,水平加速到发射速度。And that, in effect, is what engineers at Airbus, Europes largest civil-aviation company, are proposing in their latest bout of blue-sky thinking.实际上,这是空中客车公司的工程师们在其最近一次天马行空的想法中提出的建议。Apart from the fact that the trolley would be powered by linear-induction motors rather than rockets, they are suggesting that the fantasy of 1962 might become the reality of 2050.滑车由线性感应电动机提供动力,而非火箭,除此之外,他们认为1962年的幻想会在2050年成为现实。Mindful that many passengers are aly nervous about the whole process of getting a plane airborne, the engineers prefer to call their proposal Eco-climb.考虑到飞机离开地面的整个过程中已经够让许多乘客紧张了,工程师更喜欢将他们的提议称为环保型起飞。But the idea is straight out of Fireball.但这一想法是直接来自于雷霆机的。The aircraft to be launched would sit on a platform that ran along a track where the runway would otherwise be.待发射的飞机会架在一个沿轨道滑行的平台上,而这轨道可说是跑道的另一种形式。The platform would accelerate to take-off speed, at which point the plane would lift into the air powered by its own engines.平台会加速到起飞速度,到达这一速度点后,飞机便可以通过自己的引擎升上天空。Taking off in this way would both save fuel and make life more pleasant for those who live near airports.以这种方式起飞既可以节约燃料,又能够让住在机场附近的人过的更舒心些。Aircraft engines are optimised for level flight at cruising speed in the stratosphere.飞机引擎最适合在平流层以巡航速度水平飞行。Using them to accelerate a plane on the ground wastes a lot of fuel.在地面上用它们为飞机加速会浪费很多燃料。An induction-motor-powered platform, by contrast, would be optimised for the job at hand.相比之下,由感应电动机提供动力的平台最适合手头的这个工作,It could launch the plane at higher speed, letting it climb faster.它能以更快的速度发射飞机,让飞机爬升更快,That would save fuel, too.还能节约燃料,It would also mean fewer people on the ground suffered aircraft noise.还意味着地面上要经受飞机噪音的人更少了。And it could do all this from a track that was a third shorter than a conventional runway.所有这些在一条比传统跑道短三分之一的轨道上即可完成。Altogether, according to Airbuss back-of-the-envelope calculations, Eco-climb would reduce fuel consumption by 3% on a typical 900km flight, even with existing aircraft designs.总而言之,很据空中客车的粗略计算,按一次典型的900公里的飞行算,即使按照现在的飞机设计,环保型起飞也能将其油耗减少3%。But it would also allow for the design of lighter aircraft, with smaller engines, which would cut fuel consumption, noise and emissions further.而且它还为设计引擎更小,重量更轻的飞机留下了空间,可以进一步降低油耗,噪声及排放。Nor is the idea complete fantasy. General Atomics, an American military contractor, has aly built and tested a linear-induction-motor-based system of this sort at an airbase at Lakehurst, New Jersey.这个想法并不完全是幻想。通用原子公司是一家美军的承包商,其已经在一座位于新泽西州莱克赫斯特的空军基地建造了一个这类基于线性感应电动机的系统,并进行了测试。The General Atomics system is now being scaled up to be fitted on a new generation of aircraft carriers for the American navy.目前通用原子正在对该系统进行放大,以便能装备到美国海军的新一代航空母舰上。A launcher powered by a linear-induction motor has several advantages over the steam-driven catapults used on existing aircraft carriers, according to General Atomics.据通用原子公司称,与现在航空母舰上使用的蒸汽动力弹射器相比,由线性感应电动机提供动力的发射台有多个优点。Whereas a steam catapult lets rip with a constant force, the speed and power of a linear motor can be controlled to provide smooth acceleration.恒定的力使蒸汽弹射器难以控制;而线性电动机的速度和力量都可以控制,可带来平缓的加速,That extends the life of an aircraft by subjecting it to less stress.因为承受的压力更小,所以能够延长飞机的寿命,It also makes for a more comfortable take off.并且能让起飞时更舒一些。And the launch shuttle can brake quickly once the plane has lifted off by reversing the current running through the motor.飞机一旦起飞,通过反转电动机中的电流,发射装置能够快速制动,然后返回原位准备下一次发射。What works in a military context might not, of course, be appropriate for civil aviation—one reason why nobody has considered equipping airports with steam catapults.当然,在军事中使用的技术不一定适合民用航空,这也是为什么没人会考虑在机场配备蒸汽弹射器的一个原因。But the smooth operation of a linear motor means the take-off force could be kept within the 2.5g typically felt in a modern airliner dashing along a runway.但是线性电动机的平缓运行意味着起飞的力会在2.5倍重力加速度之内,与一架现代的客机沿着跑道加速时的感觉一样。Passengers need not be subjected to Top Gun levels of acceleration.乘客们不需要去承受《壮志凌云》那种级别的加速度。It might be possible to use linear motors for landings, too.将线性电动机用于着陆也是有可能的。Carrier-style arrester wires would cause too much damage and would hardly be comfortable for passengers.航母式的拦截索会是飞机产生很多损伤,而且乘客也不会舒。But if an incoming aircraft landed on a moving platform equipped with a linear motor, the current in the motor could then be reversed to slow it down.但如果一架准备降落的飞机在一个装有线性电动机的移动平台上着陆,电动机中的电流会反转,使飞机减速。That might mean planes could do without landing gear, saving still more weight. Even Mr Anderson didnt think of that one.这或许意味着飞机没有起落架也行,能让飞机再轻一些。Fireball XL5 landed vertically, on retro-rockets.安德森先生都没有想到这种方法,雷霆机是靠制动火箭垂直着陆的。 /201401/272960Anyone who s gothic fiction will tell you that vampires are bad news. People who modern medical journals, however, might disagree–in fact, they think vampires just might help save lives.读过哥特小说的人都会说吸血蝙蝠是个讨厌的东西。而那些读现代医学杂志的人也许不同意这样的观点,他们认为吸血蝠能帮助拯救生命。The kind of vampire I’m talking about is Desmodus rotundus, commonly known as the “vampire bat.” Yep, these little creatures are real; and even though they almost never turn into suave Romanian counts to drool over, they do drool a lot themselves. That’s because their saliva is an essential part of their dining habits.我说的是圆形叶口蝠,俗称“吸血蝙蝠”。是的,这些小家伙是真实的,尽管它们几乎没有垂涎于温雅的罗马利亚人,但它们却经常流口水,因为唾液是它们饮食习惯中的必不可少的一部分。When a vampire bat latches onto, say, a steer, it needs to keep the blood flowing from the puncture made by its teeth. That’s achieved by a natural anti-coagulant in the vampire bat’s saliva. Despite what you see in the movies, vampire bats almost never drink human blood. But people do suffer from other blood problems–a leading one being stroke.当吸血蝙蝠缠在,比如一直公牛身上时,必须保持血液从牙齿咬开的孔流过。这是通过蝙蝠唾液里一种天然的抗凝血剂来实现的。尽管你会在电影里看到,吸血蝙蝠几乎从来不吸人的血。但人类患有其它血液疾病——最重要的就是中风。Stroke is caused by a clotting in the blood which stops the flow and can starve areas of the brain of oxygen. Doctors have generally broken up clots with a compound called tPA. TPA works okay, but it has dangerous side effects, and can even hurt brain cells.中风是由于血液凝结成块阻碍其流动,从而导致大脑部分缺氧。医生们已经找到了分解血液凝块的化合物,就是tPA。TPA很有效,但具有危险的副作用,甚至会损伤脑细胞。A better idea? Bring in the bats, says researcher Robert Medcalf, a biochemist from Australia. Vampire bat spit contains a different compound, DSPA, which does the good things tPA does with far fewer side-effects. DSPA is now being tried on patients who have suffered a stroke; the data should be in within a year. If it works, doctors might have found an unlikely friend–the vampire bat.有更好的主意吗?澳大利亚生物化学家,Robert Medcalf对蝙蝠进行研究。吸血蝙蝠的唾液中含有一种不同的化合物,DSPA,它能够帮助减少tPA引起的副作用,DSPA现在正在患有中风病人身上测试,结果将于一年内揭晓。如果有效的话,医生们也许多一位意想不到的朋友——吸血蝙蝠。 /201304/233706

Science and technology科学技术Prospecting for oil石油勘探Grains of truth千虑一得之法Putting rocks in medical scanners may help the search for oil and gas采用医学扫描仪对岩石样本扫描,可帮助寻找石油和天然气STRIKING oil is one thing.开采石油是一回事。Getting it out of the ground in economic quantities is quite another.然而从经济角度考虑,能从地下开采出多少石油又完全是另一回事。Doing so depends on understanding the granular structure of the rock it is trapped in,要做到这点,人们需要对某些岩石的颗粒结构有所了解,而这些岩石是有石油困于其中的。分and analysing that is a tedious business of placing countless samples in pressure vessels to assess their capacity to hold hydrocarbons and to estimate the flow rate of those hydrocarbons through them.析岩石颗粒结构是极其枯燥乏味的事情,研究人员需要将无数个样本放置在压力容器内以评估它们含纳碳氢化合物的能力并估計其中蕴藏的碳氢化合物的产量。This can take years.这可能需要花费数年的时间。Help, though, is at hand.然而可施之法即在眼前。Computerised tomography scanning has been used in medicine for several decades.计算机X线断层照相扫描术在医学领域应用已有几十年时间。Now it is being applied to geology.目前它正被应用于地质学。In alliance with electron microscopy, the geological use of CT scanning has given birth to a new field, digital rock physics.在与电子显微镜配合使用下,CT扫描术在地质上的应用育了一个新的领域—数字岩石物理。The fields proponents believe it will let oil companies decide far more quickly than they could in the past which strikes are worth exploiting, and which should be abandoned.该领域的倡导者认为,该项技术能使石油公司较之以往更加快速地判断哪些石油矿值得开发,哪些应该放弃。One of those proponents is Amos Nur, chief technology officer at, a company based in Houston, Texas.科技公司Ingrain总部设在得克萨斯州休斯敦,其首席技术官阿莫斯?努尔是该技术倡导者之一。His firm is one of three independent digital-rock-physics laboratories in the world.他所在公司是全球三家独立数字岩石物理实验室之一。According to Dr Nur, the new technology is capable of creating three-dimensional pictures of a samples structure with a resolution of 50 nanometres.努尔士表示,这项新技术能为岩石样本结构创建分辨率为50纳米的三维立体照片。That is enough to work out how oil and gas trapped in the pores between the grains of such a rock might be expected to behave.这足够预测出困在岩石颗粒细孔间的石油和天然气的表現方式。Most of the samples analysed by Ingrain start as cylindrical cores brought up from deep below the Earths surface by drills.开始分析的大部分样本都来自于地下深层钻探得到的圆柱形岩石核。A typical core is several metres long, so it is first subject to a rough and y CT scan using a standard medical scanner.典型的岩石核有几米长,因此首先要采用标准医学扫描仪对其进行粗略的CT扫描。The scanner is fitted with calibration rods made of a proprietary material whose properties provide reference points for the creation of an image.该扫描仪安装了许多由专利材料制成的调校棒,这种材料有为图像创建提供参考点的属性。This initial scan yields a picture that has a resolution of about 500 microns.初始扫描会得到一张分辨率为500微米的图片。That done, sections of the core 2-3cm long, whose porosity is of particular interest, are subject to further study.这些完成之后,将一些长度在2至3厘米间,其孔隙度有特殊研究价值的小岩石块做进一步研究。This involves scanning them in a special micro-CT machine, of a sort developed originally to look at computer chips.这包括将岩石核样本放入一台特殊的微CT机进行扫描—微CT机原是为了观察电脑芯片而研制的。The sample is placed on a turntable and rotated inside this microscanner.将小岩石核样本放置在微扫描器内部的转盘上并使其旋转,The result is a 3D image with a resolution of 40 microns.结果得到一个分辨率为40微米的三维图像。This allows sections requiring further study to be identified.这就使得需做进一步研究的小岩石块能够被标识。These sections are dissected, using a laser, into slices a millimetre or less thick, and then scanned again, either with the micro-CT or with a scanning electron microscope.采用激光将这些小岩石块切分成一毫米或不太厚的薄片,然后用微CT机或电子显微扫描镜对其再次扫描。That brings the resolution to half a micron, or 500 nanometres.这样便将图象分辨率提高到了0.5微米或500纳米。Finally, the image is cleaned up by a computer program and the 50-nanometre-resolution picture emerges.最后,将该图像进行计算机降噪去斑处理,得到一张50纳米分辨率的图片。This image, which shows the porosity of the rock, and the channels between the pores,然后将能够显示岩石孔隙度和岩石内部毛孔间通道的图像用计算机分析,is then subject to a computer analysis that reveals how easily hydrocarbons will flow through it under pressure—and thus the likely productivity of a well dug at that site.结果会显示在有压力情况下碳氢化合物在岩石块内部流动的容易程度—从而得知样品来源之处那口钻探井的可能产量。Whether digital rock physics will actually replace traditional methods is unclear.“数字岩石物理”技术是否能够取代传统方法,目前尚无定论。Sceptics, such as Anthony Kovscek of Stanford University, think the claims being made for it are exaggerated.许多人对此持怀疑态度,斯坦福大学的Anthony Kovscek就是其中之一,他认为该技术的声明有夸大成分。Though analysis of a rocks structure in this way will, in his opinion, be able to tell you that a strike is unlikely to yield a commercial return,在他看来,尽管采用这种方法得出的岩石结构分析结果能够告知人们哪个钻探点不可能产生商业回报,the reverse is not true.但其反面结论却未必正确。He does not believe that the technique can predict flow rates,他不相信这种技术能预测石油的流量,even from rock that contains a lot of hydrocarbons—and flow rates are crucial to an oil fields economics.即使对于含有大量碳氢化合物的岩石也无法预测—石油流量是油田经济中至关重要的指标。The new discipline of digital rock physics has, nevertheless, attracted considerable attention within the industry.但是“数字岩石物理”这门新学科在行业内引起了相当大的关注。Smaller oil companies are using the facilities of Ingrain, Numerical Rocks and Digitalcore.小型石油公司正在使用Ingrain、Numerical Rocks和Digitalcore的设备。Larger ones, such as BP, Chevron and Shell, are setting up their own digital-rock-physics laboratories.而大型石油公司—如BP、雪佛龙和壳牌正在创建自己的数字岩石物理实验室。As the supply of crude oil dwindles and the price thus rises, anything that makes the process of prospecting new wells cheaper is to be welcomed. This new technique may be such a thing.当原油供应下降并导致价格上升之时,任何能使新井勘探成本更低的技术都将受到欢迎。“数字岩石物理”可能就是满足此要求的新技术。 /201305/239868

And all this meat in one small area attract the scavenger, the short-faced bear. Led by his super sensitive nose, his long limbs carry him many miles a day in search of carrion. Hes picked up a scent, but wheres the carcass? Sometimes the smaller, speedier scavenger gets there first, on this occasion a coyote.在这一小片区域的腐肉吸引来了短面熊,腐肉是它的主食。凭借极度敏感的嗅觉和长长的前肢,短面熊为了寻找腐肉能一天行进数英里。它闻到了气味,可肉在哪?有时,体型更小,速度更快的食腐动物能够更快找到腐肉,这次恰恰是一只丛林狼。Right now the short-faced bear will take whatever he can get. He hasnt had a decent meal in days, and needs at least one good-sized carcass every week to stay alive. This time the coyotes left him nothing but the skeleton. But with his huge, bone-crunching jaws, the bear can crack them open for the marrow locked inside.现在,这只短面熊已经变得饥不择食。它数日没有吃到一顿像样的了。为了存活,它每周至少吃一只大型动物的尸体。这次,这只丛林狼除了一个头骨什么也没有留下。但是短面熊的巨掌能将骨头拍碎,它可以拍开头骨,吃到头骨里面的精华。With water so scarce elsewhere, animals from miles around converge here in the valley, which is good news for the local lions—their pride territory is now overflowing with food.由于其他地区水源缺乏,几英里外的动物们纷纷聚集在这片山谷里,这对山谷里的狮子们来说是一件好事,因为他们引以为傲的领地中到处都是食物。Once the midday heat subsides, the females rouse themselves to hunt.一旦正午的炎热过后,雌性狮子们便会出去觅食。英文文本来自普特英语,译文属.201305/241870

  • 飞度排名动态新闻网湖州去除纹身的方法
  • 湖州市菱湖人民医院打溶脂针多少钱
  • 南浔区去红血丝价格
  • 飞度管家快问湖州曙光医院隆胸
  • 飞度管家医院排名湖州激光脱毛那里好
  • 湖州曙光整形美容医院鼻尖整形怎么样
  • 飞度技术养生问答网湖州打玻尿酸隆鼻哪家医院好
  • 湖州无痛祛斑费用
  • 湖州第三医院激光去斑多少钱
  • 飞度管家医院大全湖州市双林人民医院打瘦脸针多少钱
  • 湖州三院光子脱毛多少钱飞排名公立医院
  • 长兴县注射丰太阳穴多少钱
  • 湖州曙光整形美容医院祛眼袋手术多少钱飞度咨询名医湖州曙光整形美容医院祛雀斑
  • 湖州黄褐斑图片
  • 湖州哪些公立有皮肤美容科飞排名健康调查湖州福音医院玻尿酸多少钱
  • 南浔区脂肪丰胸价格飞度快问答网
  • 飞度指定医院湖州市中心医院激光去黄褐斑多少钱
  • 德清县妇幼保健院治疗痘痘多少钱
  • 浙江湖州市做狐臭手术多少钱
  • 湖州祛痣最好
  • 安吉县人民医院做双眼皮手术多少钱飞管家快对话网湖州哪家医院割双眼皮好
  • 湖州中医院抽脂多少钱飞度新闻快速问答网
  • 湖州曙光整形美容医院修眉毛怎么样
  • 度排名健康管家湖州市做颧骨整型多少钱
  • 湖州我想嘴唇下嘴唇变薄
  • 湖州治疗眼部松弛飞度技术动态新闻网
  • 飞管家服务平台湖州治疗痘痘哪里好
  • 湖州割双眼皮开眼角那家医院好
  • 湖州中心整形医院祛痘多少钱
  • 吴兴区祛除胎记要多少钱
  • 相关阅读
  • 明天开始一年内赚的盆满钵满穷的只剩钱的生肖
  • 百倍的热情千遍的呵护万分的用心品鉴华菱星马运煤专线上
  • 洛阳城市建设勘察设计院有限公司招聘信息
  • 阿梅你真的学了中医比较擅长是哪一方面的?你是在乡下学的吗
  • 深圳互金协会发布通知严禁成员单位开展首付贷等违规业务
  • 乌兰察布市召开十三五人才发展规划座谈会
  • 《梦想的声音》本周逆势上扬田馥甄浓妆惊艳颠覆
  • 特朗普要废了耶伦?华尔街的小心脏都要跳出来了!
  • 车市之星专访上海锦俊总经理尤悦梅
  • 地铁时代常青城暂无房源可售(图)
  • 编辑:飞排名服务平台