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    The United States is a country of immigrants. It is a place where people from all over the world come to build a better life. Some immigrants bring their families. Some bring a few of their favorite things. Others come alone with nothing but determination. One thing that every immigrant brings with them is their culture.

    American immigration began in 1607 with the colony (殖民地) of Jamestown. In 1620, another group of people left England to build a settlement in America. They wanted to go to a place where they could practice their religion freely. Then many more people left their homes in Europe to build a better life in America. Many also came to America from Africa. By 1770, more than two million people had moved to America. Later on, more people came to the United States than ever before.

    In cities all over America, you can see different cultures that formed this country. Many things that you may think of as being “American” are actually from a foreign culture. Some of the best examples of this are the foods people eat. Pizza and spaghetti are foods that all Americans know and love. But both of them are from Italy. Baseball is an all-American sport. But the hot dogs that people eat during the game are a type of food that was brought to America by German immigrants.

    Over time, pizza and hot dogs have become a part of what is considered to be American food. In the same way, different groups of people have come together to define what an American is. An American can be a person of any background. An American can be of any faith. An American can be of any skin color. They can speak English clearly. They can speak English with an accent. Each new immigrant adds something new to American culture. It will keep changing as more people come to this country.

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                                                                                                   熊胆的悲剧
                                                                                                       刘 夙
        ①即使你不是一个动物权利保护主义者,当你听到在中国有几千头国家二级保护动物黑熊被关在狭窄的笼子里几乎不能动弹,它们的肚子上被活活割开一个口子,被人用金属管子捅进去,而它们因此痛不欲生的时候,你多少也会感到于心不忍吧?
        ②为什么这些黑熊会受到这样的虐待?因为人们想获取它们的胆汁。但是如果把熊杀死,一次只能取得一点点胆汁,于是便有“天才”想到可以用“取卵不杀鸡”的办法获取熊胆汁,也就是把一根导管伸到活熊的胆管内,一旦分泌出胆汁就把它导引出来。
        ③动物的胆到底有什么药效?李时珍在《本草纲目》中是这么说的:“目者,肝之外候,胆之精华也。故诸胆皆治目病。”简单地说,就是中医认为眼睛和肝、胆有密切的关系,肝胆有问题,眼睛也会有问题;而根据“吃啥补啥”的法象药理,吃胆就可以补胆,补了胆,眼睛的病自然也就好了,所以各种胆都可以明目。
        ④动物的胆又被认为具有“苦寒”的性味,而苦寒之药常常是用来“降火”的,“火症”里面有一大类叫做“肝火”,既然是肝的“火”,用胆来治当然是最恰当不过的,所以胆又有了清热的功能。
        ⑤在过去,除了熊胆之外,猪胆、牛胆、蛇胆和青鱼胆也常常使用,它们与熊胆合称“五胆”。熊胆在后来之所以一下子受到狂热的追捧,而另外四胆中除蛇胆之外却已经很少有人使用,全在于现代医学的一个发现。
        ⑥现代医学发现:胆汁的一大功能是把肝脏中的一些脂溶性排泄物——主要是胆红素和胆固醇——带离肝脏。在正常的胆汁中,胆红素和胆固醇也是被胆汁酸盐包裹成乳滴而悬浮其中的;如果胆汁成分异常,胆红素或胆固醇过量,胆汁酸盐没法把它们全都紧紧地包住,它们便会在进入十二指肠之前从胆汁中沉淀出来,形成胆结石。实验发现,口服胆汁酸或其盐,在某些时候的确可以起到溶解结石的效果。因此,从上世纪70年代起,口服溶石成了不动手术治疗胆结石的一种方法。
        ⑦但是,胆汁酸有很多种,包括胆酸、去氧胆酸、鹅去氧胆酸和熊去氧胆酸等,而且不同动物的胆汁有不同的成分,如人胆汁中的胆汁酸以胆酸、去氧胆酸和鹅去氧胆酸为主。熊去氧胆酸,在一些熊类(特别是黑熊)的胆汁中含量较高,但在其他哺乳动物的胆汁中却不存在或仅以微量存在。
       ⑧在这么多种胆汁酸中,如果鹅去氧胆酸是效果最好的溶石药物,那么今天人们祸害最多的就该是鸡鸭鹅等家禽,而不是熊了。不幸的是,实验表明,偏偏熊去氧胆酸的溶石效果比鹅去氧胆酸更好,而且毒副作用也更小,于是,胆熊的悲剧就这样开始了。今天从胆熊获得的熊胆汁,有的直接干燥成“熊胆粉”,用在中成药里面,但大部分都用来提取熊去氧胆酸了。   
       ⑨这时候,中医支持者其实已经把中医中动物胆原本的用法抛弃了,不过是在用一种野蛮落后的方式获取天然的熊去氧胆酸罢了。可是,熊去氧胆酸并非只能从熊胆汁中获取,用人工合成的方法,可以很容易把鹅去氧胆酸或其他某些胆汁酸转成熊去氧胆酸,成本并不比活熊取胆汁的方法高多少。                   (摘自“科学松鼠会”网站,有删改。)