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2020年02月28日 03:28:14来源:69常识

  • The broad basis of life on Earth iscarbon-based and requires water. Carbon is much more versatile as a buildingblock for complex molecules than, say, silicon, the favourite element forspeculations about alternative alien biochemistries.地球上生命的广泛基础是基于碳和需要水。碳作为复杂分子的构建元素,比诸如硅这样在推测另类的外星人生化组成时最受青睐的元素要全能得多。As well as sugars, life on Earth needed aminoacids, the building blocks of proteins. But we know that these can be formed inouter space too, because they have been found in ;primitive;meteorites. They might be made from some variation of a chemical reactioncalled the Strecker synthesis, after the 19th-Century German chemist whodiscovered it. The reaction involves simple organic molecules called ketones oraldehydes, which combine with hydrogen cyanide and ammonia. Alternatively,light-driven chemistry triggered by ultraviolet light will do the job.和需要糖一样,地球上的生命也需要蛋白质的构成元素氨基酸。但我们知道这些也可在外太空形成,因为在“原始的”陨石中发现过它们。它们可以从被称为“斯特雷克合成反应”的化学反应的一些变化中产生,这个化学反应是19世纪德国化学家斯特雷克发现的。该反应涉及简单的有机分子酮或醛,它们与氰化氢和氨结合。或者,紫外线触发的光驱动化学反应也可以做这个工作。It looks at first as though these reactionsshould not take place in deepest space, without a source of heat or light todrive them. Molecules encountering one another in frigid, dark conditions donot have enough energy to get a chemical reaction started.乍一看,这些反应似乎不会在幽深的没有热源或光源驱动的太空发生。分子在寒冷黑暗的环境中相遇并没有足够的能量引发化学反应。However, in the 1970s the Soviet chemistVitali Goldanski showed otherwise. Some chemicals could react even when chilledto just four degrees above absolute zero. They just needed a bit of help fromhigh-energy radiation such as gamma-rays or electron beams –like thecosmic rays that whizz through all of space.然而,20世纪70年代,苏联化学家戈尔丹斯基明情况并非如此。一些化学物质甚至被冷却至只有绝对零度以上4度时,也能发生反应。它们只需要伽玛射线或电子束等高能射线助一臂之力- 这些射线就像嗖嗖穿过太空的宇宙射线。Under these conditions, Goldanski foundthat the carbon-based molecule formaldehyde, which is common in molecularclouds, could link up into polymer chains several hundred molecules long.戈尔丹斯基发现,在这种情况下,常见于分子云中的碳基分子甲醛可联结成长达几百个分子的聚合物链。Goldanski believed that such space-basedreactions might have helped the molecular building blocks of life assemble fromsimple ingredients like hydrogen cyanide, ammonia and water.戈尔丹斯基认为,这种以太空环境为基础的反应或可帮助生命的构建分子从氰化氢,氨和水等简单成分中形成。But it is far more difficult to coax suchmolecules to combine into more complex forms. Ultraviolet and other forms ofradiation can induce reactions. But they are just as likely to smash moleculesas they are to form them. Potential biomolecules – progenitors of proteins andRNA, say –would be broken apart faster than they were being produced.但诱使这类分子结合成更复杂的形态要困难得多。紫外线和其它形式的射线可诱导产生化学反应。但它们打碎分子的几率和形成分子的几率一样高。潜在的生物分子- 比如蛋白质和核糖核酸的祖细胞- 被分解比被制造出来要快得多。Ultimately the question is whether othercompletely alien environments would give rise to self-replicating chemicalsystems that can evolve.最终,问题在于其它完全陌生的环境是否会产生能够进化的自我复制的化学系统。 /201605/440203。
  • Back in February, Forever 21 launched a new Instagram account for its plus-size collection, something fans of the brand have wanted for a long time. But it didn#39;t go as expected.二月份,Forever 21应众多该品牌粉丝长期以来的心愿,开通了新的Instagram账号来展示大尺码系列装。但是这个账号所起的作用却不尽如人意。Most of the Insta pics were of F21+ models wearing the clothes, and many girls thought the models looked way too small and didn#39;t represent them. F21 heard the backlash and has now totally switched up the account.该Instagram账号中大多数的照片是F21+系列的模特。很多女孩认为这些模特过于瘦小,无法很好地展示衣。Forever 21察觉到了这种不满,完全改变了这个账号的风格。Gone are the models, and in place of them are real girls - bloggers, celebs, and customers. You#39;ll spot some of your fave influencers (including Dounia Tazi above) and blogger Gabi Gregg.现在,现实中不同身份的女孩,包括主、名人,还有普通消费者取代了模特们。你会发现其中有一些你最喜欢的潮流风向标(包括Dounia Tazi)和主Gabi Gregg。Some of the previous photos have been deleted. A rep for Forever 21 told Racked that it#39;s listening to its customers, saying:Forever 21删除了一些以前的照片。一位品牌代表表示,Forever 21十分关注客户的感受:;We always appreciate our customers reaching out when they have a concern and therefore have removed some of the images and are working to ensure all of our future posts accurately represent the Forever 21 Plus customer. As a majority of the content on our social media accounts is user generated by our loyal customers, we encourage them to continue to share their own photos to provide a true representation of our clothing, embracing beauty in all shapes and sizes.;“我们一直感激客户们对品牌所表达的意见,因此我们删除了一些照片。并且我们会确保未来的照片能够完完全全满足F21 +客户群体的需求。鉴于我们社交账户上大部分是品牌的忠实客户,我们鼓励大家继续分享自己的照片,为我们的衣提供真实的买家秀,并且能够展示各式各样的美。”And comments on posts have gotten better. Still, you won#39;t be able to please everyone. Some pics, including the one below, have comments that say things like, ;When this is considered plus size?;现在的相关已经有所好转。但你仍旧无法让所有人都满意,有些人会在一些照片下说:“这怎么会被认为是大号的衣呢?”But remember: girls come in ALL shapes and sizes and a size 12 or 14 or 16 might look totally different on you than it does on another girl. What#39;s important is that you see yourself represented in the media, not the number that#39;s on your - or the model#39;s - tag.但是人们需要记住,女孩们的体型各不相同,并且就算你和别人穿的尺码一样,这并不代表你们的穿衣效果相同。重要的是你在社交媒体上所呈现出的样子,而不是你或者模特所穿的尺码数字。 /201604/436272。
  • Moon Cakes月饼Celebrations are held at night with moon cakes playing a predominant role. These are small round tarts baked with different fruit fillings—date, pear,apple and pomegranate among others. People used to lay out a feast with good wine. When the moon was rising in a clear sky ,they would place the moon cakes and fresh fruit on a table as an offering. Even today a family will sit around the table, enjoying the beautiful moon and eating moon cakes and fruit. Those who are away from home try to return for a family reunion, giving the occasion its other name—Family Reunion Festival.在晚上庆祝活动,月饼发挥主导作用。这些是用小圆蛋挞和不同的水果馅,梨,苹果,石榴等等包着。人们习惯用好的葡萄酒摆盛宴。当月亮在晴朗的天空升起,他们将月饼和新鲜水果摆在桌子上使其成为供品。即使先进一家人会坐在桌旁,享受着美丽的月亮,吃月饼和水果。这些离家的人试图返回与家人团聚,给这个场合取个名字--家庭团聚日。 /201607/454243。
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