第18届国际理论与应用力学大会(ICTAM-18)

<正> 由国际理论与应用力学联合会(IUTAM)召开的4年一次的第18届国际理论与应用力学大会(ICTAM-18),于1992年8月22—28日在以色列海法市的以色列工业学院举行。大会选定的3个主题是:固体与结构力学中的不稳定性;海面力学与海气相互作用;生物力学。设置主题分会的目的是对力学中的某些重要领域做综合介绍,以强调这领域的重要性,或对新领域起提倡作用。

激光毛化技术对18-8不锈钢疲劳性能影响的研究

通过模拟分析 ,对激光毛化 18 8不锈钢的疲劳寿命与毛化覆盖率的关系进行研究 ,预测结果与相关实验结果进行对比。结果显示 ,由于激光毛化处理的影响 ,18 8不锈钢的疲劳寿命得到改善 ,而且在毛化覆盖率为 2 0 %左右时 ,材料疲劳性能最好

脉冲激光辐照ZrO_2涂层的18-8不锈钢快凝组织与精细结构

利用脉冲辐照研究超高温度梯度下表层预轩ZrO_2纳米颗粒涂层的18-8奥氏体不锈钢的快凝组织形态、微结构特征及力学性质，结果表明，在表层约15μm范围内形成Zr的合金化微区，Zr最大含量(原子分数)为43.3%，但Zr成分分布存在不连续特征；预置纳米ZrO_2陶瓷涂层明显提高了激光作用深度。超高温梯度和高冷却速度显著细化了快凝亚组织并得到超细枝晶及胞晶，并观察到位错胞及栅栏孪晶两类亚晶，而激光熔区的外延生长机制未使晶粒细化。激光辐照后，合金化区硬度增加而弹性模量降低，其余部分硬度增加而弹性模量无变化。

相位锁定双包层光纤激光器阵列获得18．3W的相干输出

光纤激光器以其结构紧凑、转换效率高、易散热和光束质量好等优点正逐渐成为高功率全固态激光器的主要选择。目前，单根光纤激光器的输出功率已经超过千瓦量级，但是由于受受激拉曼散射（SRS）和受激布里渊散射（SBS）等非线性效应的影响，单根光纤激光器的最终输出功率还是受到限制。要在保证光束质量的同时进一步提高输出功率就需要采用相干组束技术。

云南18 个民族Y染色体双等位基因单倍型频率的主成分分析

世居云南的少数民族中,壮、傣、水、布依、布朗、德昂、佤、彝、白、怒、哈尼、傈僳、拉祜、纳西、景颇、阿昌、基 诺和独龙18 个民族是由“羌”、“濮”、“越”3 大部落群体演化而来,是云南的土著居民。利用PCR2RFL P 方法对这18 个土著民族进行Y染色体上13 个双等位基因位点进行基因分型。结果显示,不同历史族源的民族群体在Y染 色体双等位基因单倍型分布上具有一定的差异:在百越后裔民族群体中以单倍型H11 、H12 为主要分布;在氐羌后 裔民族中以单倍型H5 、H6 和H8 为主要分布;在百濮后裔民族群体中主要单倍型分布为H6 、H8 和H11 。进一步 主成分分析表明,百越后裔民族群体和氐羌后裔民族在主成分图上聚为两组,提示父系基因库有不同的来源,与历 史记载相印证。

Molecular systematics of Xenocyprinae (Teleostei : Cyprinidae): Taxonomy, biogeography, and coevolution of a special group restricted in east Asia

We surveyed mitochondrial DNA (mtDNA) sequence variation in the subfamily Xenocyprinae from China and used these data to estimate intraspecific, interspecific, and intergeneric phylogeny and assess biogeographic scenarios underlying the geographic structu

草鱼呼肠孤病毒RNA聚合酶基因的表达与产物纯化

草鱼呼肠孤病毒是引起草鱼出血病的主要病原,隶属于呼肠孤病毒科水生呼肠孤病毒属。序列分析表明,GCRV S2 片段长为3 877核苷酸,编码一个分子量为138kDa 的蛋白VP2,具有RNA聚合酶性质。为进一步了解该病毒 RNA聚合酶特性,本研究在对GCRV RNA聚合酶基因(GCRV-RdRp)保守区(约1.5kb)重组质粒pR/RRp高效表达的基础上,分别构建了编码GCRV RNA聚合酶保守区N端与C端部分基因的 pR/RRpN及pR/RRpC重组表达载体,并在原核细胞中获得成功表达。筛选的重组表达菌株

南极中山站、长城站附近18个湖泊生态学特征的逐步判别分析

南极中山站、长城站附近１８个湖泊生态学特征的逐步判别分析蔡庆华，王洪铸，梁彦龄（中国科学院水生生物研究所，武汉４３００７２）关键词南极，湖泊，生态学特征，逐步判别分析，拉斯曼丘陵，乔治王岛ＳＴＥＰＷＩＳＥＤＩＳＣＲＩＭＩＮＡＮＴＡＮＡＬＹＳＩＳＦＯＲ...

无机阴离子在涂敷十六烷基吡啶的C_(18)键合相柱上的分离和测定

<正> 近年来,离子相互作用色谱法得到了迅速发展,使用这种方法,不仅可用有机树脂作固定相,同样可使用高效的键合固定相,并且可以通过改变离子相互作用,试剂在流动相中的浓度或涂敷在固定相上的量来改变柱的交换容量。实验使用常规的液相色谱仪,易于方法的广泛应用。在无机阴离子的分离中,这一方法显示了优越的分离效率。 本文研究了在涂敷十六烷基吡啶的C_8键合固定相上分离无机阴离子,并利用一些无机阴离子在

Isolation and characterization of 18 polymorphic microsatellite markers in Chinese mandarin fish Siniperca chuatsi (Basilewsky)

Eighteen microsatellite markers were isolated and characterized using an enrichment protocol in the Chinese mandarin fish Siniperca chuatsi (Basilewsky), a commercially important piscivorous fish in China. Out of 48 pairs of primers designed, 18 loci exhibited polymorphism with three to six alleles (mean 4.4 alleles/locus) and average observed heterozygosity ranged from 0.633 to 0.833 (mean 0.748) in a test population from Dongting Lake of China. Except for two loci, all other 16 loci were in the Hardy-Weinberg equilibrium. These markers would be useful for such studies as population genetics, ecology and selective breeding of the Chinese mandarin fish in future.

Effects of the phytoplanktivorous silver carp (Hypophthalmichthys molitrixon) on plankton and the hepatotoxic microcystins in an enclosure experiment in a eutrophic lake, Lake Shichahal in Beijing

The responses of nutrients, water transparency, zooplankton, phytoplankton and microcystins to a gradient of silver carp biomass (0, 18, 55, 110 g/m(3)) were assessed using enclosures in Lake Shichahai (Beijing). Picophytoplankton biomass increased with increasing fish stocking density (r=0.64, p=0.09). Silver carp significantly depressed zooplankton biomass, and thus, zooplankton grazing was too low to control phytoplankton. Intracellular microcystin (MC) content in the enclosures was correlated only to Microcystis biomass in the present study. Microcystis spp. biomass and intracellular microcystins content were much higher in lake water than those of enclosures with and without stocking fish. Stocking of silver carp could be an appropriate in highly productive Lake Shichahai, which naturally lacks of large cladoceran zooplankton. A fish stocking density of 55 g/m(3) was most efficient at controlling Microcystis blooms and increasing water clarity. Mean extracellular MC concentration in the lake water was almost the same with that of the enclosures with fish. (c) 2006 Elsevier B.V. All rights reserved.

Molecular systematics of Xenocyprinae (Teleostei : Cyprinidae): Taxonomy, biogeography, and coevolution of a special group restricted in east Asia

We surveyed mitochondrial DNA (mtDNA) sequence variation in the subfamily Xenocyprinae from China and used these data to estimate intraspecific, interspecific, and intergeneric phylogeny and assess biogeographic scenarios underlying the geographic structure of lineages. We sequenced 1140 bp of cytochrome b from 30 individuals of Xenocyprinae and one putative outgroup (Myxocypris asiaticus) and also sequenced 297 bp of ND4L, 1380 bp of ND4, 68 bp of tRNA(His), and 69 bp of tRNA(Ser) from 17 individuals of Xenocyprinae and the outgroup (M. asiaticus). We detected high levels of nucleotide variation among populations, species, and genera. The phylogenetic analysis suggested that Distoechodon hupeinensis might be transferred to the genus Xenocypris, the taxonomic status of the genus Plagiognathops might be preserved, and species of Xenocypris and Plagiognathops form a monophyletic group that is sister to the genus Distoechodon and Pseudobrama. The introgressive hybridization might occur among the populations of X. argentea and X. davidi, causing the two species to not be separated by mtDNA patterns according to their species identification, and the process and direction of hybridization are discussed. The spatial distributions of mtDNA lineages among populations of Xenocypris were compatible with the major geographic region, which indicated that the relationship between Hubei + Hunan and Fujian is closer than that between Hubei + Hunan and Sichuan, From a perspective of parasite investigation, our data suggested that the fauna of Hexamita in Xenocyprinae could be used to infer the phylogeny of their hosts. (C) 2001 Academic Press.

稳定可调谐的单纵模多环形腔掺铒光纤激光器

提出了一种多环形腔(MRC)结构的稳定可调的单纵模(SLM)掺铒光纤激光器,多环形腔结构由双环形有源腔和两个次级无源腔组成。这种激光器是利用光纤法布里-珀罗可调滤波器(FFP-TF)以及光学光栅滤波器(OGF)两种滤波器和多环形腔结构相结合来共同选模。可实现波长调节范围为1528～1565 nm,在整个波长调节范围内边模抑制比大于44.53 dB,在1554 nm附近边模抑制比可以达到最大值51.18 dB, 输出功率为-8.84 dBm,通过应用多环型腔结构,激光器的输出很稳定,在18 min的观察时间内,中心波长的变化小于0.02 nm,输出功率的变化小于0.04 dBm,实现了稳定且可调谐的单纵模输出。

1×8阵列波导光栅型波分复用/解复用器设计的一种简单方法

用有效折射率法，采用近轴近似和波导模场分布的高斯近似，简化了阵列波导光栅(AWG)器件的设计过程中繁杂的计算，且保证了器件的性能指标。给出了设计思路，并给出了1×8路、中心波长为1550.9nm，波长间隔为1.6nm的AWG波分复用/解复用器的设计实例。