利用相似理论实现植物根系参数的动态预测

应用特殊设计的营养袋纸培系统试验方法,对大豆根系的生长过程进行了研究。结果表明,大豆根系在营养袋纸培系统中的生长曲线呈S形;该方法在一定程度上可模拟植物根系的实际生长过程。此外,利用相似理论获得了实际根系生长过程中的各根构型参数。     

基于改进的双极Slope One算法的农业信息推荐模型研究

为了在海量信息中为用户提供有价值的信息,个性化在线推荐系统是农业信息化综合服务平台的重要组成部分。Slope One算法因简单高效被许多在线推荐系统使用。对Slope One算法进行研究,并结合农业信息化综合服务平台的特点,提出了农业信息推荐模型。该模型按资源类别把用户评分矩阵划分为评分子矩阵,在此基础上采用杰卡德统一算子距离相似度算法建立用户类别近邻用户,采用改进的双极Slope One算法和Item user average算法相结合的方式对未访问资源进行评分预测,有效降低计算量,并提高了评分预测精度,既适合稠密数据集,又适合稀疏数据集。     

褐飞虱的RAPD-PCR分析

采用 RAPD-PCR技术对不同地点、时间的褐飞虱 Niloparveta Lugens ( Stal)种群 (长翅型、短翅型 )基因组 DNA进行多态性研究 ,分析了各种群之间的遗传差异。结果表明 ,RAPD PCR能分析各种群之间的基因多态性 ,相似性分析和聚类分析所得的各种群之间的亲缘关系相一致。因此 ,RAPD PCR技术可以作为褐飞虱种群遗传研究的一种方法     

豫南地区猪伪狂犬病病毒流行株的主要毒力基因遗传变异分析

为掌握豫南地区猪群中流行的伪狂犬病病毒（Pseudorabies virus,PRV）分子遗传特征,本研究利用PCR方法从PRV感染猪的组织中扩增其主要毒力基因gB、gE、gC、gD和TK,并进行核苷酸序列测定。利用MegAlign软件进行流行毒株的主要毒力基因与已发表的参考序列的相似性、进化树和关键位点氨基酸变异分析。测序结果表明,本研究成功从5份PRV感染猪组织中扩增出PRV的gB、gE、gC、gD和TK基因。氨基酸相似性和进化树分析结果表明,豫南地区的5株PRV流行株与国内流行毒株在G1群,与G1群国内流行毒株的gB、gE、gC和gD氨基酸相似性分别为98.5%~100%、97.2%~100%、97.5%~100%和98.3%~100%;与G2群亲缘关系较远（以Bartha、Becker、NiA3株为代表的欧美地区流行毒株）,与G2群内毒株的gB、gE、gC和gD氨基酸相似性分别为96.4%~97.4%、94.6%~95.7%、92.7%~94.0%和96.3%~99.0%。关键氨基酸变异分析结果表明,与Bartha株（或Becker和NiA3株等）相比,5株流行毒株的gB氨基酸存在75-77位"PGL"的缺失,94位"G"的插入;gE氨基酸存在48和496位有"D"的插入,gC氨基酸存在57-63位"VSGTTGA"的插入和65-69位"SPEAG"突变为"ASTPA",gD氨基酸存在278-281位"RP"或"RPRP"的插入。此外,流行株的gB、gE、gC、gD和TK氨基酸序列存在多个单位点的氨基酸突变。因此,豫南地区PRV流行株具有PRV变异毒株的分子遗传特征。上述结果证实,5株PRV流行毒株均为变异毒株,与疫苗毒株Bartha-K61株亲缘关系较远。     

Cross-taxon congruence of species diversity and community similarity among three insect taxa in a mosaic landscape

Surrogate taxa as indicators for biodiversity are widely used in conservation biology and ecology. However, available studies on the congruence of species diversity patterns in different taxa yielded inconsistent results, and correlations between taxa were few. To conserve or restore biodiversity in agricultural landscapes, knowledge on the response of different taxa to management regimes is crucial. In the present study we evaluated the congruence of diversity and similarity patterns among three insect taxa, i.e., bees, grasshoppers, and aculeate wasps, in a mosaic landscape in the Swiss Alps comprising extensively used grassland under different management regimes. In addition, we studied the influence of land use on the diversity and species composition of the three taxa. While species numbers were not significantly correlated between any pair of taxa, community similarities were positively correlated between bees and grasshoppers. The number of red-listed species was not correlated with the total number of species in bees and in grasshoppers. None of the investigated taxa reflected the species numbers or community similarities of the other taxa well enough to qualify as a general indicator for biodiversity. Remarkably, land use clearly influenced species composition, while its effect on species numbers was not significant. All management regimes of the grassland in the study area contribute substantially to the overall diversity of the three insect taxa. Conserving the variety of agricultural land uses will be the most promising step towards the conservation of biodiversity in the study area.     

The role of cacao plantations in maintaining forest avian diversity in southeastern Costa Rica

We conducted 600 ten-minute, fixed-radius point counts in two climatically different seasons in forest, abandoned cacao (Theobroma cacao), and managed cacao habitat from September 1997 through April 1998 in the Talamanca lowlands of Costa Rica. A total of 1,464, 1,713, and 1,708 individual birds and 130, 131, and 144 total species were detected in forest, abandoned cacao, and managed cacao, respectively. Independent of season, cacao habitats had a significantly greater number of individuals and species per point than forest. Community similarity analyses based on guild categorizations revealed a significant degree of similarity among all habitats; however, habitat affinity analyses showed cacao habitats having significantly less forest specialists than forest. A multiple linear regression model for actively managed cacao habitat using habitat and landscape variables revealed density and diversity of canopy tree species to be significantly correlated with numbers of forest specialist species detected per point. Although nearest distance to forest was negatively correlated with the number of forest specialist species per point, it was not a significant variable in the model, possibly indicating the complex and unpredictable nature of bird movements within the complex habitat mosaic of Talamanca. The present forest bird community of the Talamanca lowlands is poor in forest specialist species relative to other forested Caribbean lowland sites. The broad patterns of avifaunal distribution illustrated by our results suggest, therefore, that although cacao plantations cannot substitute for forest, they provide habitat for a large number of species which depend to some degree on forests. This revised version was published online in June 2006 with corrections to the Cover Date.     

特征组合在地质图像检索中的应用

为了将基于内容的图像检索技术应用到地质图像的分析与检索中,在使用灰度直方图和Gabor小波变换进行特征提取的基础上,提出了一种使用灰度及纹理这两种特征结合对目标图像进行分析检索的算法。试验结果表明,在进行图像特征相似度匹配时选取合适的相似度阈值,该算法能够取得满意的检索效果。     

非洲菊部分品种资源遗传多样性的ISSR分析

为了揭示非洲菊品种资源的遗传多样性,并更好地应用于育种工作,利用ISSR分子标记技术对75份非洲菊材料进行了遗传多样性研究。在供试材料中,筛选到具有多态性的ISSR引物29个,共扩增出多态性条带267条,平均每个引物扩增的多态性条带数为9.2条,多态性条带比率为89.3%。材料间遗传相似系数范围在0.576 1~0.883 9,这说明非洲菊具有丰富的遗传多样性。通过软件计算结果表明,75个非洲菊品种平均有效等位基因数为1.655 8,Nei基因多样性指数平均为0.377 2,平均Shannon信息多样性指数为0.557 2。将非洲菊材料聚类结果与其花色、花型、管状花颜色、花径作比较,其呈现一定的相关性,这为非洲菊优良品种的选育奠定了一定的分子理论基础。     

水稻品种抗瘟性表型与抗病基因同源序列相似性关系

 用6对RGA引物，即RGA1(XLRR for/XLRR rev)、RGA2(XLRR inv1/XLRR inv2)、RGA3（NLRR for/NLRR rev）、RGA4(NLRR inv1/NLRR inv2)、RGA5(Pto kin1/Pto kin2)和RGA6(Pto kin3/Pto kin4)对21个品种进行RGA PCR的DNA指纹分析。以相似系数0.72和田间叶瘟严重度阈值0.84分别聚类，21个水稻品种均可以分成5类。尽管类与类之间没有一一对应关系，但抗谱广、抗性稳定或具持久抗瘟性的品种，能较好地聚为一类，如湘资3150、IR156、株两优02、ZR02。在6对引物中，RGA1和RGA2来自于水稻抗白叶枯病基因Xa21含 LRR结构，RGA3来自于烟草N基因含LRR结构，上述3对引物比较适宜用于水稻稻瘟病抗性基因遗传背景分析。     

基于 Mahalanobis 矩阵学习的本体算法

提出基于M ahalanobis矩阵学习的本体相似度计算和本体映射算法。利用矩阵分解和坐标下降迭代算法得到M ahalanobis矩阵,进而得到本体图距离矩阵,并由此来判定本体图中2顶点之间的相似程度。最后,将算法应用于生物GO本体和计算机软件本体,通过实验数据验证了算法的有效性。