聚乙烯醇作保护剂的反滴定共沉淀法制备纳米晶LaFeO_3

以聚乙烯醇或十二烷基苯磺酸钠作保护剂,采用反滴定共沉淀法制备纳米晶LaFeO_3的前体.     

A general approach to single-nucleotide polymorphism discovery

Single-nucleotide polymorphisms (SNPs) are the most abundant form of human genetic variation and a resource for mapping complex genetic traits. The large volume of data produced by high-throughput sequencing projects is a rich and largely untapped source of SNPs (refs 2, 3, 4, 5). We present here a unified approach to the discovery of variations in genetic sequence data of arbitrary DNA sources. We propose to use the rapidly emerging genomic sequence as a template on which to layer often unmapped, fragmentary sequence data and to use base quality values to discern true allelic variations from sequencing errors. By taking advantage of the genomic sequence we are able to use simpler yet more accurate methods for sequence organization: fragment clustering, paralogue identification and multiple alignment. We analyse these sequences with a novel, Bayesian inference engine, POLYBAYES, to calculate the probability that a given site is polymorphic. Rigorous treatment of base quality permits completely automated evaluation of the full length of all sequences, without limitations on alignment depth. We demonstrate this approach by accurate SNP predictions in human ESTs aligned to finished and working-draft quality genomic sequences, a data set representative of the typical challenges of sequence-based SNP discovery.     

浅谈流体在流管出口下游形成“缩脉”的物理实质

一般流体,在流出管口后均有形成“缩脉”的现象.该文就流体在流出管口后,形成“缩脉”的物理实质进行了定性的分析,将其归结为在流管出口附近,流体受管口发出的扰动波的影响,而形成“缩脉”.     

Internet网络考试系统

将计算机与网络技术应用于教学考试领域是一个值得探讨的问题,本文详细描述了该考试试系统的指导思想、系统模块、设计原则及运行环境.     

两圆内外公切线方程的求法

讨论了圆的切线及两圆内外公切线的一般求法及步骤。