检索结果-南通市图书馆

Impact Analysis of Genetically Modified (Bt) Cotton Genotypes on Economically Important Natural Enemies under Field Conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Entomology 2016年第2期4卷 61-74页

作者： Dalip Kumar Surender Singh Yadav Vivek Kumar Saini Krishan Kumar Dahiya Department of Entomology College of Agriculture CCS HAU Hisar India Government College Hisar India Cotton Section Department of Plant Breeding and Genetics CCS HAU Hisar India

Field studies were conducted at Hisar during Kharif, 2009-2010 and 2010-2011 under natural and unsprayed condition. RCH 134 Bt, HS 6 (non Bt), H 1117 and Ganganagar Ageti (non Bt) were selected for the studies. The experiment was laid down in Randomized Block Design replicated thrice having plant spacing 67.5 × 60 cm. Among the bollworms, Erias spp. exhibited positive correlation with rainfall, minimum temperature and relative humidity morning hours significantly at 5 percent level whereas Helicoverpa and Pectinophora displayed positive relations only with evening hours relative humidity significantly while Spodoptera were significantly positive correlated with relative humidity of morning and evening hours. Bollworm complex was negatively correlated with all the weather parameters employed to study although being non-significant in case of rainfall, maximum and minimum of temperature, morning and evening hours of relative humidity. Among the sucking pests, leafhoppers, whitefly, thrips and aphids population showed significantly negative correlation with weather parameters. The comparison of natural bio-agents in cotton hybrids under study revealed that overall mean population of natural enemies were higher in Bt cotton hybrid as compared to non-Bt. These results confirm that use of genetically modified (Bt) cotton in lieu of conventional genotypes could positively impact non-target and beneficial insect species by preserving their host populations.

关键词： Bt Cotton Natural Enemies Sucking Pests Bollworm Complex population dynamics Correlation Co-Efficient Abiotic Factors

ULTIMATE BOUNDEDNESS FOR A DIFFERENTIAL DELAY MODEL

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Annals of Differential Equations 2004年第2期20卷 118-124页

作者：李林 Dept of Math Beijing Institute of Petrochemical Technology Beijing 102617

This paper considers the scalar differential delay equation x(t) = -μx(t)-f(x(t-Τ(t)), t). By using the mapping method we obtain that the solutionswill be ultimately in some interval.

关键词： differential delay equations population dynamics ultimate boundednesss

SIR model applied in dynamics of COVID-19 contagion in S˜ao Lu´ıs-MA,Brazil

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

International Journal of Modeling, Simulation, and Scientific Computing 2021年第3期12卷 99-111页

作者： Felix Silva Costa Italo Jose Lima De Sousa Jose Adson Reis Santos Department of Mathematics and Informatics State University of Maranhao Sao Luıs MA 65054-970Brazil

The dynamics of COVID-19 contagion investigated in S˜ao Lu′ıs-MA,Brazil,is based on the SIR model.S˜ao Lu′ıs was the first city in Brazil to implement the lockdown to control the disease.The SIR model’s definition and properties are presented in addition to the ways of estimating its parameters.The estimation of their values is due to a database released on the Maranh˜ao State Health Department website during the period March 20 to July 2,2020.The analysis of the proliferation of the disease shows the evolution of the COVID-19 in the city.The graphs illustrate that result.

关键词： COVID-19 population dynamics SIR model

An Overview of Oligocene to Recent Sediments of the Western Pacific Warm Pool(WPWP)(International Ocean Discovery Program-IODP Exp.363)Using Warm and Cool Foraminiferal Species

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Marine Science 2021年第3期3卷 21-35页

作者： Patrícia Pinheiro Beck Eichler Christofer Paul Barker Moab Praxedes Gomes Helenice Vital Programa de Pós-Graduação em Geodinâmica e Geofísica(PPGG) Universidade Federal do Rio Grande do Norte(UFRN)Campus UniversitárioLagoa Nova59072-970-NatalRNBrazil Ecologic Project Boulder CreekCaliforniaUnited States

We use the excellent sediment recovery of International Ocean Discovery Program(IODP)Exp.363,in the Western Pacific Warm Pool(WPWP)to assess down-core variations in the abundance of warm versus cool benthic foraminiferal species through a warm benthic foraminifers(WBF)curve.The total percentage of the“warm”shallower species group(Laticarinina pauperata,Cibicidoides kullenbergi,C.robertsonianus,Cibicidoides sp.,Hoeglundina elegans,and Bulimina aculeata)and of the“cool”species group from deep waters(Pyrgo murrhina,Planulina wuellerstorfi,Uvigerina peregrina,and Globobulimina hoeglundi,Hopkinsina pacifica)at all sites is used to assess paleo temporal and spatial variations in preservation and marine temperature.Our study sites span water depths ranging from 875 m to 3421 m and our results indicate that well-preserved living and fossil foraminifera characterize mudline and core sediments at all water depths attesting the wide environmental tolerance of these species to temperature and pressure.Using magneto-and biostratigraphy datum,these sediments are of Oligocene age.Our low-resolution study showed that with the exception of core 1486B which the linear tendency of warmer species is toward cool sediments in old times,all of them show that older sediments indicate warmer periods than today,which is expected from Miocene to Recent.Our results provide evidence for the preservation potential of deeply buried sediments,which has implications on climate reconstructions based on the population dynamics of calcareous benthic foraminifera.

关键词： Miocene population dynamics Climate change Tolerance Temporal Spatial

A Theory of Ratio Selection—Lattice Model for Obligate Mutualism

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Ecology 2016年第6期6卷 303-311页

作者： Kei-Ichi Tainaka Tsuyoshi Hashimoto Graduate School of Science and Technology Shizuoka University Hamamatsu Japan Department of Information Engineering National Institute of Technology Matsue College Matsue Japan

Mutualisms are cooperative interactions between members of different species. We focus on obligate mutualism, where each species cannot survive without the other. From a theoretical aspect, obligate mutualism is similar to the relationship between male and female. Empirical data indicate a sex-ratio selection: male and female have a specific ratio in their population sizes. In the present paper, we apply lattice model to obligate mutualism between two species, and present a theory of “ratio selection” which is a generalization of sex-ratio selection. Computer simulations are carried out by two methods: local and global interactions. In the former, interactions occur between neighbouring cells, while in the latter they occur between any pair of cells. Simulations in both interactions show the so-called Allee effect: both species can survive, when both densities are large in some extent. However, we find a large difference between local and global simulations. In the case of local interaction, restriction for survival is found to be extremely severe compared to global interaction. Both species require a proper ratio for their sustainability. This result leads to the theory of ratio selection: when interaction occurs locally, the ratio of both species is uniquely determined. We discuss that the ratio selection explains not only the evolution of endosymbionts from free-living ancestors but also the evolution from endosymbionts to organelles.

关键词： Obligate Mutualism population dynamics Ratio Selection Allee Effect Lattice Model Sex-Ratio Selection Endosymbiosis

Occurrence Regularity of Major Damage Generations of Nilaparvata lugens(Stl) in Single Cropping Medium Rice Region in Sandu County of Guizhou Province

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plant Diseases and Pests 2014年第2期5卷 4-9页

作者： Liu Tianlei Jin Daochao Yang Hong Ai Zhengxian Zhou Zhaoxia Guizhou Provincial Key Laboratory for Agricultural Pest Management of Mountainous Region Institute of EntomologyGuizhou University Sandu Plant Protection Station

In order to clarify occurrence regularity of major damage generations of Nilaparvata lugens( Stl) in Sandu Shui Autonomous County( Sandu County for short),Guizhou Province,a karst single cropping medium rice region,the population dynamics of N. lugens were systematically studied using the methods of light trap and systematic field survey from 2009 to 2011. The results showed that the number of immigration generations caught by light trap and the actual population of N. lugens in fields were different among three years. The daily maximum trapping numbers of N. lugens amounted to 6 688 in 2009,which were 15. 3 and 2. 5 times of that in 2010 and 2011,respectively. The peak numbers in prediction nursery were 10 777,4 630 and 1 615 heads per hundred hills in 2009,2010 and 2011,respectively. The forth and fifth generations of N. lugens were the major damage generations in single cropping medium rice fields,and the initial immigration day was significantly related with primary-peak day. The occurrence degree of adults and nymphs of N. lugens varied with years and transplanting periods,and the peak days of N. lugens nymphs were from late July to early August in 2010 and 2011. The occurrence peaks of adults and nymphs in late transplanting paddy field were later than that in the early one. Meanwhile,the coexisted various growth periods of rice,due to time differences of transplanting,were conducive to inhabitation and reproduction of N. lugens. The population dynamics of spiders and Cyrtohinus lividipennis well synchronied with that of N. lugens,but predatory capacity of spiders and C. lividipennis was not enough to control N. lugens.

关键词： Nilaparvata lugens(Stl) population dynamics Single cropping medium rice Occurrence regularity

The State of Persian Wheatear Oenanthe chrysopygia de Filippi,1863 in Armenia

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Life Sciences 2020年第1期14卷 9-13页

作者： Karen Aghababyan TSE towards Sustainable Ecosystems NGO 87b Dimitrovapt 14Yerevan 0020Armenia

The monitoring of Persian or Red-tailed Wheatear Oenanthe chrysopygia was conducted during 2003-2019.The species breeds at the foothills of Urts and Meghri mountain ridges at elevation range from 700 to 1,200 meters above sea level and inhabits rocky semideserts.The total suitable habitat for Red-tailed Wheatear is estimated as 128.4 km2.The species disappeared at several gorges where larger scale new orchards have been launched.The population of Persian Wheatear makes from 70 to 105 breeding pairs.During last ten years the population shows moderate decline,p<0.05,which is mostly caused by launching of new orchards which occupy natural breeding habitat of the species.Although the species is evaluated as endangered in Armenian Red List,the existing conservation measures are insufficient and should include the following:(1)lobbying official adoption of the species distribution range into the Emerald Network protected under Bern Convention;(2)development of management plans for these Emerald Sites,which will consider a strict policy towards new orchards in the semi-deserts of Meghri and Urts mountains;(3)obligatory environmental impact assessment of any new orchard projects in those areas;(4)introduction of eco-friendly concepts in the horticulture in these areas.

关键词： Persian Wheatear Red-tailed Wheatear Oenanthe chrysopygia Armenia conservation status distribution population dynamics threats

Fertility Decline and population Growth:China's Dilemma

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China population Today 1996年第1期13卷 15-15页

作者： B Gu

ＦｅｒｔｉｌｉｔｙＤｅｃｌｉｎｅａｎｄＰｏｐｕｌａｔｉｏｎＧｒｏｗｔｈ：Ｃｈｉｎａ＇ｓＤｉｌｅｍｍａＣｈｉｎａｈａｓａｔｐｒｅｓｅｎｔａｐｏｐｕｌａｔｉｏｎｏｆｏｖｅｒ１．２ｂｉｌｌｉｏｎ，ｗｈｉｃｈｉｓｍｏｒｅｔｈ... 详细信息

ＦｅｒｔｉｌｉｔｙＤｅｃｌｉｎｅａｎｄＰｏｐｕｌａｔｉｏｎＧｒｏｗｔｈ：Ｃｈｉｎａ＇ｓＤｉｌｅｍｍａＣｈｉｎａｈａｓａｔｐｒｅｓｅｎｔａｐｏｐｕｌａｔｉｏｎｏｆｏｖｅｒ１．２ｂｉｌｌｉｏｎ，ｗｈｉｃｈｉｓｍｏｒｅｔｈａｎｔｈｅｐｏｐｕｌａｔｉｏｎｏｆ...

关键词： Asia China Demographic Factors Developing Countries Eastern Asia Economic Factors Fertility Fertility Decline Obstacles Organization And Administration Policy population population dynamics population Growth population Policy Poverty--women Social Policy Socioeconomic Factors

Statistics about Beijing population and Relevant Issues

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

China population Today 1997年第2期14卷 10-10页

作者： G Zhang

Statistics from the pub lic security bureau indicate that the total popula tion with household re gistration in Beijing was 10.77 million by the end of 1996.Survey data show that the resident population in the city wa... 详细信息

关键词： Asia China Demographic Factors Developing Countries Eastern Asia Economic Factors Human Resources Income Labor Force population population Characteristics population dynamics population Growth population Statistics Research Methodology Rural population Socioeconomic Factors Urban population