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涵道螺旋桨式反扭矩系统气动特性工程计算方法研究 被引量:1
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作者 孙传伟 《直升机技术》 2008年第3期35-40,共6页
分别采用涡流理论、面元—薄翼型和源—汇模型的组合建模方法建立了包括螺旋桨、涵道体和中心体模型在内的反扭矩系统气动特性分析程序,并分别以BellX-22涵道螺旋桨及Doak涵道螺旋桨系统为算例,计算和分析了轴流和斜流情况下、在不同前... 分别采用涡流理论、面元—薄翼型和源—汇模型的组合建模方法建立了包括螺旋桨、涵道体和中心体模型在内的反扭矩系统气动特性分析程序,并分别以BellX-22涵道螺旋桨及Doak涵道螺旋桨系统为算例,计算和分析了轴流和斜流情况下、在不同前进比时,涵道螺旋桨系统的气动特性,并得到了涵道体内外表面压力分布规律。 展开更多
关键词 涵道 螺旋桨 气动 兰金体 涡流 源一汇
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Phylogeny in Chloranthus Swartz (Chloranthaceae) Inferred from Sequence Analysis of nrDNA ITS Region 被引量:3
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作者 孔宏智 陈之端 《Acta Botanica Sinica》 CSCD 2000年第7期762-764,共3页
The internal transcribed spacer (ITS) regions of nuclear ribosomal DNA from ten species of Chloranthus Swartz and two outgroup species of Sarcandra Gardn. were sequenced. The regions ranged in length from 654 to 663 b... The internal transcribed spacer (ITS) regions of nuclear ribosomal DNA from ten species of Chloranthus Swartz and two outgroup species of Sarcandra Gardn. were sequenced. The regions ranged in length from 654 to 663 bp, with ITS1 (285-290 bp) slightly longer than ITS2 (205-211 bp). Of the 669 aligned positions, 109 sites (56 in ITS1, 52 in ITS2, and one in 5.8S region) were phylogenetically informative. Only one most parsimonious tree of 252 steps was obtained in PAUP analysis when gaps were treated as the fifth state. The traditional division of Chloranthus on the basis of habit seems to be quite unnatural. Evidence from the sequence of ITS region, just as that from cytology and anatomy, strongly suggested the separation of the genus into two groups according to the characteristics of androecial organs: one contains C. angustifolius, C. nervosus, C. japonicus and C. fortunei, and the other comprises the remaining species. 展开更多
关键词 Chloranthus Swartz PHYLOGENY ITS
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