2012-07-27 封面上是一幅伪色扫描电子显微图像，图中展现的是在一个被感染的老鼠肝脏中，先天免疫细胞和寄生虫Trypanosoma brucei（紫色部分，长度约为15微米）的活动情况。这种寄生虫通过受到感染的采采蝇叮咬，在哺乳动物宿主之间传播，包括人类在内，并且这种寄生虫也是人类昏睡症的罪魁祸首，这种病症在非洲是一种致命疾病，会给人类生活带来严重影响，因而采采蝇也被称为睡病蝇。
False-colored scanning electron microscopy image of innate immune cells and the parasite Trypanosoma brucei(purple; length: 15 micrometers) in an infected mouse liver. The parasite is transmitted between mammalian hosts, including humans, by the bite of infected tsetse flies and is responsible for human sleeping sickness, a lethal disease that is a serious problem in Africa.
2012-08-03
封面上是天鹅座X-1中的黑洞图示，天鹅座X-1是距离我们6 000光年的一个双星星系。大量恒星物质聚集成圆盘状，为中心的黑洞提供养料，其质量是太阳的15倍，而直径不超过60千米。当这些恒星物质朝黑洞运动时，其中的一部分会被喷射出黑洞，如图所示，物质被喷射向两个完全相反的方向。
Illustration of the black hole in Cygnus X-1, a binary star system 6000 light-years away. A disk of stellar material feeds this black hole, which is 15 times as massive as the Sun but less than 60 kilometers across. As it falls toward the black hole, some of the material gets expelled in two opposite jets.
2012-08-10
封面上是在美国费城一个废品处理站打好包的回收铝罐，这只是有效处理世界上越来越多废品的众多方法之一。在本期的“废品处理”一文中，讲述了人们为了应对这一全球性挑战所作出的多层面努力。
Recycling aluminum cans(shown here in bales at a facility in Philadelphia, PA) is just one of the many approaches directed toward doing something productive with the world’s ever-expanding stream of waste. In the special section Working with Waste, we survey multifaceted efforts to tackle this global challenge.2012-08-17
封面上是一只雄性独角仙（泰国独角仙）正挥舞着它头上巨大的分叉独角。雌雄性别选择可能有利于夸大的特征尺寸的进化，因为生物发展机制决定了生长速度以及信号可靠性。
Male rhinoceros beetles(Trypoxylus dichotomus) wield a huge forked horn on their heads. Sexual selection may favor the evolution of exaggerated trait sizes because the developmental mechanism responsible for increased growth also results in signal reliability.
（陶 陶 编译）
