应用RAPD标记研究不同生态区谷子品种的遗传差异

应用RAPD标记对19份国内不同生态区的谷子品种的遗传变异进行了研究。结果表明：分子水平上，不同生态区的谷子品种存在一定的遗传差异，但遗传差异程度并不高。11个随机引物共扩增出54条多态性带，不同引物扩增的带数差异较大，每个引物可扩增2～8条多态性带，平均每个引物扩增出4.91条多态性带。引物1050扩增的多态性带最多（8条）。聚类结果表明，基于RAPD标记分析的遗传聚类群与生态类型有很大的一致性。

Phylogeography of Pinus tabulaeformis Carr. (Pinaceae), a dominant species of coniferous forest in northern China

How coniferous trees in northern China changed their distribution ranges in response to Quaternary climatic oscillations remains largely unknown. Here we report a study of the phylogeography of Pinus tabulaeformis, an endemic and dominant species of coniferous forest in northern China. We examined sequence variation of maternally inherited, seed-dispersed mitochondrial DNA (mtDNA) (nad5 intron 1 and nad4/3-4) and paternally inherited, pollen- and seed-dispersed chloroplast DNA (cpDNA) (rpl16 and trnS-trnG) within and among 30 natural populations across the entire range of the species. Six mitotypes and five chlorotypes were recovered among 291 trees surveyed. Population divergence was high for mtDNA variation (G(ST) = 0.738, N-ST = 0.771) indicating low levels of seed-based gene flow and significant phylogeographical structure (N-ST > G(ST), P < 0.05). The spatial distribution of mitotypes suggests that five distinct population groups exist in the species: one in the west comprising seven populations, a second with a north-central distribution comprising 15 populations, a third with a southern and easterly distribution comprising five populations, a fourth comprising one central and one western population, and a fifth comprising a single population located in the north-central part of the species' range. Each group apart from the fourth group is characterized by a distinct mitotype, with other mitotypes, if present, occurring at low frequency. It is suggested, therefore, that most members of each group apart from Group 4 are derived from ancestors that occupied different isolated refugia in a previous period of range fragmentation of the species, possibly at the time of the Last Glacial Maximum. Possible locations for these refugia are suggested. A comparison of mitotype diversity between northern and southern subgroups within the north-central group of populations (Group 2) showed much greater uniformity in the northern part of the range both within and between populations. This could indicate a northward migration of the species from a southern refugium in this region during the postglacial period, although alternative explanations cannot be ruled out. Two chlorotypes were distributed across the geographical range of the species, resulting in lower levels of among-population chlorotype variation. The geographical pattern of variation for all five chlorotypes provided some indication of the species surviving past glaciations in more than one refugium, although differentiation was much less marked, presumably due to the greater dispersal of cpDNA via pollen.

基于PC平台的机器人控制设计与实现

本文首先回顾了机器人控制器的发展历史,重点介绍了我们承担的国家八六三课题“基于PC高档机器人控制器开发”的研制情况.该控制器具有开放、模块化、可靠、高效、通用的特点.

一种基于知识的室外景物分析系统

本系统是一个室外景物分析系统，主要内容有：（1）图象的分割：介绍分割数值的选择，分割数值的验证，细节的提取等问题。（2）特征数据库的构造：包括对区域、边界线、直线等特征的提取和描述，层次化的区域数据结构。（3）以知识为基础的识别过程：以图象模型为基础，采用从上至下和从下至上相结合的控制机构。本系统在分割数值的选择、验证，区域和线条相结合的分析过程以及控制过程有一定的独到之处。本文对区域分析、线条分析的作用和局限性加以讨论，认为区域分析和线条分析相结合的分析过程更有利于图象的识别。本系统对包括天空、路面、建筑物、树木、路面障碍物的室外景物做了成功的解释，并附有实验结果。