Science museums have paradoxes at their core. They must be accessible and fun while representing increasingly complex science. They must be both historic and contemporary. Their exhibits attract millions, but most of their objects remain in deep storage, seldom seen. This book delves into these conflicts, revealing the secret lives of science curators; where science objects com...(展开全部)

Science museums have paradoxes at their core. They must be accessible and fun while representing increasingly complex science. They must be both historic and contemporary. Their exhibits attract millions, but most of their objects remain in deep storage, seldom seen. This book delves into these conflicts, revealing the secret lives of science curators; where science objects com...(展开全部)

在准备本书第6版时，我想将一些对电力系统有较大影响的新内容介绍给大家，其中有以下5部分内容。 第13章、12.23～12.26节介绍了双馈感应电机的原理与特性。该电机的调速可通过在定子加固定频率交流电，而在转子通入可变频率交流电来实现，故名为“双馈”。双馈电机原来用作变速电动机来驱动大型水泵等负载，现在，该电机在风力发电中作为双馈发电动机使用。由于风力发电的重要性，有必要在本书中介绍这种特殊的电机。 第21章、21.45～21.51节对PWM的相关内容作了重要的修改，增加了新的内容及图片。 第23章介绍了几种电动机调速的电子控制方法。23.31～23.40节特别介绍了直接转矩控制（DTC）方法，与应用PWM及矢量控制方法不用，DTC使用了砰砰控制法，其对速度及转矩的控制与其他方法不同，该章根据感应电机原理，对此做了直观的分析。 第24章、24...(展开全部)

P．D．詹姆斯是英国当代最著名的推理小说女作家，被尊称为“推理小说第一夫人”。出生于1920年的P．D．詹姆斯自1950年开始写作，至今笔耕不辍。她已出版近20部作品，她的大部分作品均被拍成电视剧或电影。 P．D.詹姆斯的作品曾经多次获得英美推理小说奖。1987年荣获有“诺贝尔推理文学奖”之称的英国推理小说家协会“钻石匕首奖”终身成就奖，并受英国皇室勋封为女伯爵，1999年荣获美国推理小说家协会大师奖，也曾获爱伦坡奖。P.D.詹姆斯现任英国作家协会主席。

“Rich in dexterous innuendo, laugh-out-loud humor and illuminating fact. It’s compulsively readable.” — Los Angeles Times Book Review The best-selling author of Stiff turns her outrageous curiosity and insight on the most alluring scientific subject of all: sex. 16 illustrations

Neamen's Semiconductor Physics and Devices, Third Edition. deals with the electrical properties and characteristics of semiconductor materials and devices. The goal of this book is to bring together quantum mechanics, the quantum theory of solids, semiconductor material physics, and semiconductor device physics in a clear and understandable way.

Museums are at a critical moment in their history. In order to ensure survival into the next century, museums and galleries must demonstrate their social relevance and use. This means developing their public service functions through becoming more knowledgeable about the needs of their visitors and more adept at providing enjoyable and worthwhile experiences. Museums and Their...(展开全部)

Museums are at a critical moment in their history. In order to ensure survival into the next century, museums and galleries must demonstrate their social relevance and use. This means developing their public service functions through becoming more knowledgeable about the needs of their visitors and more adept at providing enjoyable and worthwhile experiences. Museums and Their...(展开全部)

Questions on the origins and meaning of dreams are as old as humankind, and as confounding and exciting today as when nineteenth-century scientists first attempted to unravel them. Why do we dream? Do dreams hold psychological meaning or are they merely the reflection of random brain activity? What purpose do dreams serve? When Brains Dream addresses these core questions about ...(展开全部)

Told in rhyming text, Excavator, Bulldozer, Crane Truck, Dump Truck, and Cement Mixer will all need to work together as they tackle their biggest job yet--a massive building.