成功还是失败？

遥远超新星或许在横跨宇宙的半路上，但它们已经在地球上引起了—场激烈的争论。两年前，天文学家们发现，这些叵星爆炸比预期的暗弱——两者差异的程度相当大，看来要用空间结构本身来解释。超新星反常的暗弱表明，宇宙的膨胀可能正在加速，而不是像宇宙学家一直认为的那样在减速。但是现在八位超新星观测人员担心，他们的引人注目的发现同其它某些有争议的     

明星糗事大起底

Halle BerryHits,Runs哈莉·贝瑞撞车后逃离现场Tour Stop: If you' re cruising along the famous Sunset Strip in West Hollywood, be sure to stop by Doheny Drive and Sunset Boulevard, the site of Halle Berry' s hit-and-run incident in February 2000. Seems Berry' s Blazer collided with another woman's Sunbird, both drivers were injured - and Berry ran off. The actress pleaded no     

The nature of discrimination learning in pigeons

The results from five experiments are considered in relation to two of Spence's (1937, 1938) proposals concerning discrimination learning. In Experiments 1 and 2, we investigated whether his ideas about the interaction between excitatory and inhibitory generalization gradients can be used to understand how animals solve a complex patterning discrimination. The results supported a development of his proposals as put forward by Pearce (1994), provided a modification was made to Pearce's rulefor determining the shape ofthe generalization gradient. In Experiments 3, 4, and 5, we examined whether animals would pay more attention to stimuli that are relevant, rather than irrelevant, to the solution of a discrimination. The results supported this proposal for stimuli comprising visual patterns, but not for those comprising plain colors. The results also indicated that change of attention was a consequence of preliminary receptor-exposure acts, as envisaged by Spence, and not of more central changes in attention.     

不可能性的定理

我们在通常谈话中说到某件事情不可能时，我们的意思常常并不是指它真的不可能，而是说我们还看不到有什么办法可以解决这件事情。以前许多人曾认为比空气重的机器飞起米是不可能的，而更早之前还有许多人认为比水重的机器要浮在水卜是不可能的。但人的智慧不断地克服了这些乍看起来似乎是不可能的事情。     

机械性出错

根据摩尔定律，计算机的运算速度和内存能力大约每18个月翻一番，据此所推今天的主流PC机性能可以大大超过以往的高档主机。如果你确实不想要正确答案的话，那就去相信上面的说法吧。对此我可不敢苟同。因为摩尔定律有一个     

搜寻中微子

搜※寻※中※微※子郭凯声译余炎校地球上难得再有一处地方拥有南极大陆上连续数月的漆黑而明净的天空这一优越条件,它使南极冰盖成了天文学家探寻星空的一块新圣地。然而,目前在南极进行的最富有革命性的天文学项目要利用的却不是南极的清晰视野,而是它那异常洁净的冰...     

寻找其他行星

寻找其他☆行星郭凯声译林木校大约一年半以前,天文学家们发现有一颗与木星相似的行星绕着飞马座５１号星运行（飞马座５１是一颗距地球约４０光年的类日恒星）。现在天文学家们正在争论通过哪种方式从空间进行这类行星探索活动最为合适。在用地面望远镜寻找太阳系外的...     

乔治·华盛顿对部队的演说

本文是乔治·华盛顿在独立战争中对部队的演讲。乔治·华盛顿（1732～1799）为美国的奠基人,第一任总统。出身大种植园主家庭,早年在英国殖民军中服役,后任第一届和第二届大陆会议代表。1775年北美独立战争爆发,被推选为十三州起义部队总司令。