大尺寸单晶金刚石同质连接技术

介绍了制备人造单晶金刚石的技术途径及发展现状,重点讨论并对比了几种化学气相沉积法(CVD)金刚石制备技术的优缺点,详细阐述了基于微波等离子体CVD (MPCVD)法的同质连接技术——一种突破晶体尺寸限制,实现大尺寸单晶金刚石的有效途径。通过该技术实现了英寸级单晶金刚石晶片的制备,并针对横向生长、界面质量及演化、三维结构连接控制等核心科学技术问题进行了分析和讨论,展望了其在尖端应用领域的发展前景。     

打造"天梯"上九霄

纳米技术到底会为我们带来什么呢?下面我们举一个例子也许会让你获得一些感性认识。     

丝茧可用于人造皮肤

有助于减肥和控制糖尿病的新药就要面市了。根据2003年6月份美国糖尿病协会第63届年会上讨论的研究成果，可以利用消化道中的荷尔蒙研制药物来抵制和降低血糖浓度。科学家们已经鉴别出20多种可以用作药物的荷尔蒙。     

论公共服务市场化中政府的定位

公共物品的单一政府供给并不能实现资源的优化配置，社会公共需求的扩张与政府有限供给能力的矛盾使得公共服务市场化已成为一种趋势。新公共管理发展了传统的公共服务模式，它将商业价值观念移植至公共部门而提高了管理效率的同时，却错置了公共管理中公益价值的优先性。因而有必要重塑公共服务市场化过程中政府的重要作用。     

人造细胞

本书是至今为止对人造细胞以及相关领域最为全面的概述。作为该书的作者，Thomas Ming Swi Chang，加拿大的华人科学家，有着对人造细胞深厚的造诣。从他第一次设计人造红血球细胞到现在50多年的时间里，他一直活跃于这一领域。在这本书中，作者从当初对人造细胞不可思议的想法娓娓道来；像叙述历史一样讲述了人造细胞从简单的构思到复杂的分子机制以及应用的经历，并且预测了今后人造细胞的发展方向。     

Samples Selection for Artificial Neural Network Training in Preliminary Structural Design

An artificial neural network (ANN) is applied in the preliminary structural design of reticulated shells. Major efforts are made to enhance the generalization ability of networks through well-selected training samples. Number-theoretic methods (NTMs) are adopted to generate samples with low discrepancy, i.e.uniformly scattered in the domain, where discrepancy is a quantitative measurement of the uniformity. The discrepancy of the NTM-based sample set is 1/6-1/7 that of samples with equal spacing. In a case study,networks trained by NTM-based samples are compared with those trained by equal-spaced samples in generalizing performance. The results show that both the computational precision and stability of the former ANNs are more satisfactory than those of the latter. It is concluded that the flexibility of ANNs in generalizing can be effectively increased by use of uniformly distributed training samples rather than simply piling data.More reliable uniformity should be obtained, however, through NTMs instead of equal-spaced samples.