2 GHz无线电波在煤矿井下隧道传播的研究

采用均匀间隔的延时抽头线模型对2GHz的无线电波在煤矿井下隧道传播的情况进行了研究。研究表明：对于宽带无线电信号，在煤矿井下隧道传播时均方根时延扩展是70ns，与实际测量值相符合。     

Diversification of Sisorid catfishes (Teleostei: Siluriformes) in relation to the orogeny of the Himalayan Plateau

Science Bulletin - Sisorid catfishes are primarily limited in distribution to rivers of the Himalayan region and Tibetan Plateau. These species have external morphologies that are adapted for...     

Phylogenetic studies of Chinese labeonine fishes (Teleostei:Cyprinidae) based on the mitochondrial 16S rRNA gene

The mitochondrial 16S ribosomal RNA gene is sequenced from 24 ingroups taxa, including 18 species from Labeoninae grouped in 13 genera. Phylogenetic analyses are subjected to neighbor joining, maximum parsimony, maximum likelihood and Bayesian analyses. Phylogenetic analysis indicates that Labeoninae is basically a monophyletic assemblage and can be divided into 2 major clades: one comprising the genera Cirrhinus, Crossocheilus and Garra; and the other consisting of the genera Labeo, Sinilabeo, Osteochilus, Pseudoorossocheilus, Parasinilabeo, Ptychidio, Semilabeo, Pseudogyricheilus, Rectori and Discogobio. According to our present analysis,the features such as the presence of the adhesive disc on the chin and the pharyngeal teeth in 2 rows used in the traditional taxonomy of Labeoninae provide scarce information for phylogeny of labeonine fishes.     

求解0-1背包问题的混合遗传算法

对于0-1背包问题设计一种价值密度,并在此基础上提出求解0-1背包问题的混合遗传算法.经大量数值实验比较该方法与传统方法及简单遗传算法,结果表明算法能有效求解0-1背包问题.     

催化动力学光度法测定痕量铬研究进展

基于铬对某些氧化还原反应的催化作用 ,可用催化动力学光度法测定痕量铬 ,灵敏度一般在 1 0 - 8g mL～ 1 0 - 1 0g mL之间 ,用于环境水样、粮食、合金等样品中铬的测定 ,取得了满意结果。本文就催化动力学光度法测定痕量铬 (Ⅵ )和铬 (Ⅲ ) ,按不同催化体系 ,从反应条件、灵敏度、测定范围和应用等方面加以归纳和讨论     

提高钻机弧齿圆锥齿轮工作寿命因素探讨

在钻机里常采用弧齿圆锥齿轮提高角传动齿轮承载能力。但在实际应用中，钻机中弧齿圆锥齿轮常损坏。该文分析了影响钻机弧齿圆锥齿轮工作寿命的因素，并提出了改进措施。     

Sequence analysis of cytochrome b gene indicates that East Asian group of cyprinid subfamily Leuciscinae (Teleostei: Cyprinidae) evolved independently

The sequences of mitochondrial cytochrome b gene of cyprinid subfamily Leuciscinae are analyzed. Phylogenetic trees generated with methods of neighbor-joining, maximum likelihood and maximum parsimony with Phenacogrammus as an outgroup indicate that Leuciscinae is not a monophyletic group but includes two discrete subgroups. The East Asian group of the subfamily Leuciscinae, including the genera Ctenopharyngodon, Elopichthys, Luciobrama, Mylopharyngodon, Ochetobius, and Squaliobarbus, is close to Aristichthys and Hypophthalmichthys, and they form a monophyletic group which is distant from the leuciscine genera in Europe, Siberia and North America, such as Phoxinus, Leuciscus, Abramis, Rutilus, Chondrostoma, Alburnus, Opsopoedus, Lythrurus, and Pimephales. Our study suggests that the diversified East Asian group of the subfamily Leuciscinae should have an independent origination.     

数据包的拦截与过滤研究与实现

数据包的拦截与过滤广泛应用于信息安全产品的研发中,如防火墙、入侵检测系统、病毒防范等。本文介绍了NDIS驱动程序结构,给出NDIS中间驱动程序实现网络数据包的拦截方法;并实现了一个基于规则的过滤算法,在过滤算法中引入了一个分层框架。     

Sequence variations of theS7 ribosomal protein gene in primitive cyprinid fishes: Implication on phylogenetic analysis

Cyprinidae is the largest fish family in the world and contains about 210 genera and 2010 species. Appropriate DNA markers must be selected for the phylogenetic analyses of Cyprinidae. In present study, the 1st intron of the S7 ribosomal protein (r-protein) gene is first used to examine the relationships among cyprinid fishes. The length of the 1st intron obtained by PCR amplification ranges from 655 to 859 bp in the 16 cyprinid species investigated, and is 602 bp in Myxocyprinus asiaticus. Out of the alignment of 925 nucleotide sites obtained, the parsimony informative sites are 499 and occupy 54% of the total sites. The results indicate that the 1st intron sequences of the S7 r-protein gene in cyprinids are rich in informative sites and vary remarkably in sequence divergence from 2.3% between close species to 66.6% between distant species. The bootstrap values of the interior nodes in the NJ (neighbor-joining) and MP (most- parsimony) trees based on the present S7 r-protein gene data are higher than those based on cytochrome b and the d-loop region respectively. Therefore, the 1st intron sequences of the S7 r-protein gene in cyprinids are sensitive enough for phylogenetic analyses, and the 1st intron is an appropriate genetic marker for the phylogenetic reconstruction of the taxa in different cyprinid subfamilies. However, attempts to discuss whether the present S7 r-protein gene data can be applied to the phylogeny of the taxa at the level of the family or the higher categories in Cypriniformes need further studies.     

Molecular evolution of connective tissue growth factor in Cyprinidae (Teleostei: Cypriniformes)

Connective tissue growth factor (CTGF) plays an important role in regulation of cell growth, differentiation, apoptosis and individual development in animals. The study of sequences variation and molecular evolution of CTGF gene across various species of the cyprinid could be helpful for understanding of speciation and gene divergence in this kind of fish. In this study, 19 novel sequences of CTGF gene were obtained from the representative species of the family Cyprinidae using PCR amplification, cloning and sequencing. Phylogenetic relationships of Cyprinidae were reconstructed by neighbor-joining (NJ), maximum parsimony (MP), maximum likelihood (ML) and Bayesian method. Oryzias latipes from the family Cyprinodontidae was assigned to be the outgroup taxon. Leuciscini and Barbini were clustered into the monophyletic lineages respectively with the high nodal supports. The estimation of the ratio of nonsynonymous to synonymous substitution (dN/dS) for the various branches indicated that there stood the different evolution rates between the Leuciscini and the Barbini. With the ratio of dN/dS of the Leuciscini being lower than that of the Barbini, species within the Barbini were demonstrated to be subjected to the relatively less selection pressure and under the relaxable evolution background. A 6 bp indel (insertion/deletion) was found at the 5' end of CTGF gene of Cyprinidae, and this 6 bp deletion only appeared in the Leuciscini, which is a typical characteristic of the Leuciscini and provides evidence for the monophylogeny of the Leuciscini. For the amino acid sequences of CTGF protein, the most variations and Indels were distributed in the signal region and IGFBP region of this protein, implying that these variations were correlated with the regulation of the CTGF gene expression and protein activity.