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呼市永泰整形美容医院割双眼皮多少钱

楼主:千龙资讯 时间:2018年10月24日 06:44:51 点击:0 回复:0
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This triggered other dramatic changes. As sea levels dropped, so did the inland water tables. Floridas fresh water drained away through the porous limestone rock. Pools dried up and springs diminished. Florida was on the brink of drought. And animals would have had to travel to find food and water. So each year, mastodons would have migrated to the wetter regions. 这引起了其他的一些巨大变化。海平面越降越低,内陆水位也是一样。佛罗里达的淡水都从多孔的石灰岩中流走。小水池和泉水都干涸了。佛罗里达处于干旱的边缘。动物们必须长途跋涉以寻找食物和水源。因此,每年乳齿象都是迁徙都更加湿润的地区。But in a few key places, water was still pushed up from underground as a spring, a vital oasis where wildlife would have converged from many miles around. Many animals would have fed on the surrounding vegetation and others come here to drink. And predators would have laid an ambush for the unwary. Its no wonder that so many fossil bones have been found on the bottom of these springs, clues that can open up a window on the ice age past. 但是在一些关键的地区,淡水还是能够从地表流出形成泉水,这就成型了一个重要的绿洲,几公里外的动物们都会因此聚集到一起。很多动物都会以周围的植被为食,也有一些只是到这里饮水。而肉食动物则会在这里埋伏着,准备对那些不警惕的动物们来个出其不意。毫无疑问,在这些泉水的河底能够发现很多化石骨骼,这些骨骼会我们更好地了解冰河时代的过去提供了重要的依据。Bringing this evidence together, we can create a living picture of this region as it was then. We can now go back 13,000 years and see what a day around one of Floridas springs might have been like. 将这些线索集合起来,我们就能够想象出这个地区过去是什么样子。现在我们返回13000年前,看看佛罗里达小溪的一天究竟是什么样子。Dawn on the southeast tip of ice age North America. On the banks of a spring-fed pool, the early grazers stir.我们会逐渐了解这次向着冰河时代的北美东南之行。在泉水的河岸处,早起的吃草动物在徘徊着。英文文本来自普特英语,译文属未经许可不得转载。201309/256506Science and technology科学技术Fundamental physics基础物理学Antimatter of fact反物质现状Researchers at CERN have held on to anti-atoms for a full quarter of an hour欧洲核子研究中心的研究人员已经让反原子停留了十五分钟。READERS who were paying attention in their maths classes may recall that quadratic equations often have two solutions, one positive and one negative.关注数字课的读者们或许会想到二次方程通常会有两个解,一个是正值,一个是负值。So when, in 1928, a British physicist called Paul Dirac solved such an equation relating to the electron, the fact that one answer described the opposite of that particle might have been brushed aside as a curiosity.因此在1928年,一个名叫保罗·狄拉克的英国物理学家给出了有关电子的一个方程的解,然而事实上,这个结果表达的是一种相反的粒子,这个结果或许会被考虑后舍弃。But it wasnt.然而事实并非如此。Instead, Dirac interpreted it as antimatter—and, four years later, it turned up in a real experiment.相反,狄拉克将其解释为反物质—并且在四年后,在现实的实验中验了它的存在。Since then antimatter—first, anti-electrons, known as positrons, and then antiversions of all other particles of matter—has become a staple of both real science and the fictional sort.从那时起,反物质—最初是反电子,也就是俗称的质子,接着就是其他粒子的反物质—这已经成了现实科学和虚构类别之间的主要组成部分。What has not been available for study until recently, however, is entire anti-atoms.这样的研究一直以来没有突破直到最近的完全的反原子的出现。A handful have been made in various laboratories, and even held on to for a few seconds.在各个实验室已经有一小部分的反原子被发现,即便它们仅仅存在了几秒钟的时间。But none has hung around long enough to be examined in detail because, famously, antimatter and matter annihilate each other on contact.不过没有一个停留了足够长的时间用以仔细地研究他们,众所周知,反物质与物质只要相遇就会湮灭。But that has now changed, with the preservation of several hundred such atoms for several minutes by Jeffrey Hangst and his colleagues at CERN, the main European particle-physics laboratory near Geneva.然而随着在欧洲核子研究中心这个在日内瓦附近主要的欧洲粒子物理实验室里,该机构的杰弗瑞?汉斯特与其同事让数百个这样的原子维护了几分钟,原来的情况现在已有所改观。The reason this is important is that Diracs equation is misleading.狄拉克方程是一种误导这个原因是很重要的一点。Antimatter cannot be the perfect opposite of matter, otherwise neither would exist at all.反物质并不是完全的反物质,否则它将无法存在。If they truly were perfect opposites, equal amounts of the two would have been made in the Big Bang,如果实际上它们是完全相反的,那么相同的数量的反物质早在大爆炸产生时就已经互相湮灭了,and they would have annihilated each other long since, leaving only light and other forms of electromagnetic radiation to fill the universe.它们只以电磁波的形式留在宇宙中。That galaxies, stars and planets—and physicists to ponder such things—exist therefore means there is a subtle asymmetry between matter and antimatter, and that nature somehow favours the former.星系,恒星以及行星——物理学家在在仔细思考这样的事情—它们都已经存在了,这意味着在物质与反物质之间有着一些不可思议的不对称性,自然界在某种程度上是偏爱于前者。Two such asymmetries have indeed been found. But neither is big enough to explain why so much matter has survived. Being able to look at entire anti-atoms might give some further clue.两个这样的不对称性实际上已经被发现了。不过二者都不足以解释为什么如此多的物质存活了下来。对于整个反原子的研究或许能够提供进一步的线索。Last November the ALPHA collaboration at CERN, which Dr Hangst leads, managed to put positrons into orbit around 38 antiprotons—thus creating anti-hydrogen atoms—and then held on to them in a magnetic trap for a few tenths of a second.去年11月,欧洲核子研究中心由汉斯特士领导的阿尔法项目成功地将正电子放入了38个反质子周围的轨道中—因此形成了反氢原子—接着将它们放入了一个磁阱,持续了零点几秒。Now, as they report in Nature Physics, the researchers have used their device to preserve anti-hydrogen for 16 minutes .随着他们在《自然—物理学》发布报告,研究人员又利用他们的设备维持了反氢原子16分钟。This gives the anti-atoms plenty of time to settle into their ground state, the most stable condition a particle or atom can attain.这让反原子有充足的时间待在基态—这是一个粒子或原子能够达到的最稳定状态。As a result, Dr Hangst and his colleagues can look in a leisurely manner for novel ways that antimatter might differ from the common-or-garden variety.因此汉斯特士和他同事凭这种新奇的方式有充足的时间来观察反物质—这或许不同于平日的各种状态。Their first experiment will involve nudging the trapped anti-atoms with microwaves.他们的第一次实验将会用不同频率微波轻推被困的反原子。If the frequency of these microwaves is just right, they will flip an anti-atoms spin.如果这些微波的频率恰到好处,他们将会使这些反原子产生自旋翻转。That reverses the polarity of the atoms magnetic field and ejects it from the trap.这就会改变原子原来的极性和磁场,原子就会从磁阱中弹出去。The frequency needed to do this can then be compared with that which flips the spin of an ordinary hydrogen atom.这些测试的频率将会与翻转普通氢原子的频率作对比。If the two turn out to be different, it will point towards the nature of the mysterious cosmic asymmetry.如果两个频率是不同的,那么它将会指向神秘的宇宙不对称性。Besides being of huge interest, such a result would also have a pleasing symmetry of its own.除了巨大的兴趣外,这样的结果对于本身也将是一个值得欣喜的对称。The original discovery of antimatter was a nice example of theory predicting an undiscovered fact. This would be a fact that repaid the compliment by predicting an undiscovered theory.反物质的独特发现是理论预示未知世界这一说法的一个极好说明。这使得预测未知理论来获得人类的满意将成为一个事实。 /201304/235727

When you eat a fatty food, it moves through the stomach andon to the intestines.当你食用富含高脂肪的食物时,脂肪通过胃流入肠道。In the intestines, a number of processes occur to transfer fat from the foodto special fat cells in your body.在肠道中,脂肪经过一系列的消化流程从食物转化为体内的特殊脂肪细胞。First, the gall bladder produces bile that breaks the foods fat droplets into smaller droplets.首先,胆囊分泌胆汁分解食物脂肪滴,使其更小。Next,the pancreas secretes enzymes that attack the fat droplets and break them down into two parts:fatty acids and glycerol.然后,胰腺分泌胰腺酶作用于脂肪滴,将其分解为两个部分:脂肪酸和甘油。This happens because fat droplets are too big to pass through cell membranes.这是因为脂肪滴过大,无法穿过细胞膜。The broken downfat is absorbed by the cells lining the intestine, where it is reassembled into fat molecules andeventually shuttled into the bloodstream with the help of lipoprotein particles.分解的脂肪被肠粘膜细胞吸收,重组成脂肪细胞,最后负载在脂蛋白颗粒上进入血液循环。For the most part fat is stored in the fat cells that compose fatty tissue.大部分的脂肪储存在脂肪细胞内,形成脂肪组织。Think of a fat cell as a tinyplastic bag filled with a drop of fat.脂肪细胞好比一个容纳脂肪滴的塑料袋。Interestingly, fat cells do not multiply.有趣的是,脂肪细胞并不会变多。The body contains a finitenumber of fat cells that expand as they absorb fat.身体内的脂肪细胞数量有限,它们在吸收脂肪后体积膨胀。So how can you make those fat cells smaller?那么,如何使得这些脂肪细胞变小?Eat well and exercise.健康饮食和运动。When you work out, yourbody burns energy, primarily in the form of glucose.运动时,身体消耗葡萄糖以燃烧能量。After breaking down stores of carbohydratesto produce glucose, the body goes after fat, which it breaks down into fatty acids that can also beused to make glucose.当储备的碳水化合物转化成的葡萄糖被完全消耗后,身体就开始分解脂肪,由此产生脂肪酸,而脂肪酸也会产生葡萄糖。201408/324212

Everyone is familiar with the sight of robins hopping around the yard, peering into the grass or “head-cocking” to locate a nice juicy worm. In no time, they find their prey and fly off with a mouthful.后院里,知更鸟跳来跳去,注视着草丛,晃头晃脑地搜寻着可口多汁的昆虫。这样的情景相信大家都不陌生。一旦发现“猎物”,它马上叼着虫儿飞走了。Cues to find prey寻找猎物的线索Birds are known to use visual, auditory, and possibly vibrations or tactile cues to find prey, but vision is predominant.通常鸟儿们是通过视觉、听觉,有时可能是触觉(昆虫的振动)这些线索来寻找猎物,其中视觉居多。The way the robins turn their head when searching for food suggests they could be using visual or auditory cues, but it wasn’t until scientists tested robins in the lab that we really knew for sure how they find worms.从知更鸟晃头晃脑地寻找食物可以推断出视觉和听觉线索的利用,但是直到科学家们在实验室中测试,我们才真正明确知更鸟如何发现昆虫。Testing the birds测试鸟儿Birds were placed in aviaries where they could be given buried mealworms in trays of dirt.在大型鸟舍中,给鸟儿们提供面粉虫藏在泥里的托盘。To test if they were using scent to locate their prey, birds were offered trays with buried live, moving worms and dead ones. Robins found the live worms more often, suggesting they were not using scent.为了测试鸟儿是否通过嗅觉寻找猎物,托盘里分别藏有活着的昆虫和死了的昆虫。知更鸟找出的多是活着的昆虫,这说明知更鸟寻找猎物时并没有利用嗅觉。In the next test, they were given hanging food trays to keep them from touching the soil with their feet and detecting the worm’s vibrations. The trays did not affect their ability to find the worms, suggesting they do not use tactile cues.下一个测试是:把托盘悬挂起来,这样知更鸟的脚碰不到泥土,也不能探测昆虫的振动。测试并没有影响知更鸟捕捉昆虫,这说明知更鸟寻找猎物时并没有利用触觉。Sound Cues声音线索When cardboard was used as a barrier to block visual cues, the birds could still find the worms. That meant they were using another sense. A last experiment used white noise to block sound cues and the birds had more difficulty finding the worms.用纸板作为障碍物破坏视觉线索,鸟儿依然能找到昆虫。说明鸟儿是用另种线索。最后的实验利用白色噪音破坏声音线索,鸟儿寻找昆虫困难起来了。The research concluded that robins could use either visual or auditory cues alone to find worms in the soil, but probably use both. So the next time you see a robin “head-cocking” you can be fairly sure it’s listening and looking for those mouthwatering treats!研究结果是知更鸟可以利用视觉或听觉中任一线索寻找泥土中的昆虫,但是也很可能是两种皆有。所以,下次你再看见知更鸟在草丛中摇头晃脑的,你可以确定它们是通过听觉寻找垂涎的美味了! /201304/234779

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