期刊文献+
共找到6篇文章
< 1 >
每页显示 20 50 100
角倍蚜干母致瘿率与盐肤木复叶序数的相关性 被引量:4
1
作者 张燕平 廖声熙 +1 位作者 赖永祺 苏建荣 《林业科学研究》 CSCD 北大核心 2000年第5期530-534,共5页
干母的致瘿结倍效果与倍蚜在同一枝条定叶取食复叶叶片萌发的先后顺序密切相关。角倍干母致瘿率和致倍率作为评价其致瘿结倍效果的指标 ,挂蚜干母的致瘿结倍效果指标 (yi)与盐肤木复叶萌发先后序数 (xi)之间的关系可用函数表达式 yi=A(0... 干母的致瘿结倍效果与倍蚜在同一枝条定叶取食复叶叶片萌发的先后顺序密切相关。角倍干母致瘿率和致倍率作为评价其致瘿结倍效果的指标 ,挂蚜干母的致瘿结倍效果指标 (yi)与盐肤木复叶萌发先后序数 (xi)之间的关系可用函数表达式 yi=A(0 ) +A(1) xi+A(2 ) xi2 +A(3 ) xi3 表示 ;寄生于不同序数复叶之间干母的致瘿率有显著差异 ;角倍蚜在盐肤木不同复叶叶序数上的致倍率 (y3值 )的排序为 :5>4 >6 >7>3>8>9>10 >11。该结果可作为调控角倍蚜干母的发生期以应合盐肤木最适致瘿结倍的展叶物候进度的参考依据。 展开更多
关键词 角倍蚜 盐肤木 叶序数 五倍子 干母 致瘿率
下载PDF
Molecular Phylogeny of the Lardizabalaceae Based on TrnL-F Sequences and Combined Chloroplast Data 被引量:5
2
作者 王峰 李德铢 杨俊波 《Acta Botanica Sinica》 CSCD 2002年第8期971-977,共7页
The molecular phylogeny of the Lardizabalaceae is reconstructed based on chloroplast trn L_F sequences alone and combined trn L_F and rbc L sequences. The phylogenetic topologies agree well with Qin's and... The molecular phylogeny of the Lardizabalaceae is reconstructed based on chloroplast trn L_F sequences alone and combined trn L_F and rbc L sequences. The phylogenetic topologies agree well with Qin's and Takhtajan's tribal classification in both analyses. Decaisneae and Sinofranchetieae are basal clades in the phylogenetic trees and external to all other taxa in the family. Lardizabaleae consisting of Boquila and Lardizabala are well supported in both trn L_F (100%) analysis and trn L_F and rbc L combined analysis (99%). Tribe Akebieae are strongly supported by a bootstrap value of 100% in both trn L_F analysis and trn L_F and rbc L combined analysis. However, the new genus Archakebia is nested within the genus Akebia in the trn L_F trees. In the combined trees, Archakebia is sister to Akebia with high bootstrap support. The inter_relationships among three closely related genera Parvatia , Holboellia and Stauntonia are still problematic. P. brunoniana ssp. elliptica is sister to H. latifolia in both analyses with low bootstrap support. H. parviflora is nested within the Stauntonia and sister to S. cavalerieana . Therefore, these three genera of tribe Akebieae may not be monophylytic and their generic boundary and delimitation need to be further studied, by exploring more molecular data, together with more morphological characters. 展开更多
关键词 LARDIZABALACEAE molecular phylogeny trn L_F sequences rbc L sequences
下载PDF
Effects of Freezing Disaster on Green-up Date of Vegetation Using MODIS/EVI Time Series Data 被引量:3
3
作者 夏浩铭 毕远溥 杨永国 《Agricultural Science & Technology》 CAS 2009年第3期131-135,共5页
In the field of global changes, the relationship between plant phenology and climate, which reflects the response of terrestrial ecosystem to global climate change, has become a key subject that is highly concerned. U... In the field of global changes, the relationship between plant phenology and climate, which reflects the response of terrestrial ecosystem to global climate change, has become a key subject that is highly concerned. Using the moderate-resolution imaging spectroradiometer (MODIS)/enhanced vegetation index(EVI) collected every eight days during January- July from 2005 to 2008 and the corresponding remote sensing data as experimental materials, we constructed cloud-free images via the Harmonic analysis of time series (HANTS). The cloud-free images were then treated by dynamic threshold method for obtaining the vegetation phenology in green up period and its distribution pattern. And the distribution pattern between freezing disaster year and normal year were comparatively analyzed for revealing the effect of freezing disaster on vegetation phenology in experimental plot. The result showed that the treated EVI data performed well in monitoring the effect of freezing disaster on vegetation phenology, accurately reflecting the regions suffered from freezing disaster. This result suggests that processing of remote sensing data using HANTS method could well monitor the ecological characteristics of vegetation. 展开更多
关键词 Time series data EVI HANTS MODIS
下载PDF
Rainfall Forecasting Using Fourier Series
4
作者 Nasser Rostam Afshar Hedayat Fahmi 《Journal of Civil Engineering and Architecture》 2012年第9期1258-1262,共5页
The need for accurate rainfall prediction is readily apparent when considering many benefits in which such information would provide for river control, reservoir operation, forestry interests, flood mitigation, etc.. ... The need for accurate rainfall prediction is readily apparent when considering many benefits in which such information would provide for river control, reservoir operation, forestry interests, flood mitigation, etc.. Due to importance of rainfall in many aspects, studies on rainfall forecast have been conducted since a few decades ago. Although many methods have been introduced, all the researches describe the study as complex because it involves numerous variables and still need to be improved. Nowadays, there are various traditional techniques and mathematical models available, yet, there are no result on which method provide the most reliable estimation. AR (auto-regressive), ARMA (auto-regressive moving average), ARIMA (auto-regressive integrated moving average) and ANNs (artificial neural networks) were introduced as a useful and efficient tool for modeling and forecasting. The conventional time series provide reasonable accuracy but suffer from the assumptions of stationary and linearity. The concept of neurons was introduced first which then developed to ANNs with back propagation training algorithm. Although certain ANNs) models are equivalent to time series model, but it is limited to short term forecasting. This Paper presents a mathematical approach for rainfall forecasting for Iran on monthly basic. The model is trained for monthly rainfall forecasting and tested to evaluate the performance of the model. The result Shows reasonably good accuracy for monthly rainfall forecasting. 展开更多
关键词 RAINFALL forecasting Fourier series MAXIMUM 1 st year mean and minimum rainfall.
下载PDF
The art and science of species delimitation 被引量:5
5
作者 Bruce RANNALA 《Current Zoology》 SCIE CAS CSCD 2015年第5期846-853,共8页
DNA-based approaches to systematics have changed dramatically during the last two decades with the rise of DNA barcoding methods and newer multi-locus methods for species delimitation. During the last half-decade, par... DNA-based approaches to systematics have changed dramatically during the last two decades with the rise of DNA barcoding methods and newer multi-locus methods for species delimitation. During the last half-decade, partly driven by the new sequencing technologies, the focus has shifted to multi-locus sequence data and the identification of species within the frame-work of the multi-species coalescent (MSC). In this paper, I discuss model-based Bayesian methods for species delimitation that have been developed in recent years using the MSC. Several approximate methods for species delimitation (and their limitations) are also discussed. Explicit species delimitation models have the advantage of clarifying more precisely what is being delimited and what assumptions we are making in doing so. Moreover, the methods can be very powerful when applied to large multi-locus datasets and thus take full advantage of data generated using today's technologies [Current Zoology 61 (5): 846-853,2015]. 展开更多
关键词 Bayesian species delimitation Species concepts Multi-species coalescent
原文传递
The HAUSDORFF DIMENSION AND MEASURE OF THE GENERALIZED MORAN FRACTALS AND FOURIER SERIES
6
作者 REN FUThO LIANG JINRONG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 1995年第2期153-162,共10页
This paper studies the Hausdorff dimensions, the Hausdorff measures of generalized Moranfrontals and the convergence of the Fourier series of functions defined on some generalizedMoran fractals. A general formula is g... This paper studies the Hausdorff dimensions, the Hausdorff measures of generalized Moranfrontals and the convergence of the Fourier series of functions defined on some generalizedMoran fractals. A general formula is given for the calculatinn of the Hausdorff dimensions ofgeneralized Moran fractals and it is proved that their Hausdorff measures are finite positivenumbers under some conditions. In addition, the authors define an orthonormal system offunctions defilled on generalized Moran s-sets (gMs) and discuss the convergence of the Fourierseries, with respect to of each function f(x) E L1(gMs, Hs). 展开更多
关键词 Haudorff dimension Hausdorff measure s-set Differentiation base Fourier series.
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部