带时滞的单种群在n个斑块中持续生存的条件     

董淑转 《运城学院学报》2005,23(5):10-11

对[2]中的单种群扩散模型进行了推广与改进,研究了fi(xi(t-τ))=ai(t) di(t)(∑j=1xjnxj-1)n ε bi(t)xi(t-τ)-ci(t)xi2(t-τ)(i=1,2,…,n)与gi(xi(t-τ)=ai(t) di(t)(∑j=1jnxj-1)-ε bi(t)xi(t-τ)-ci(t)x2i(t-τ)(i=1,2,…,n)的正根存在性及种群密度函数的特性,利用数学分析的方法证明了在条件ai(t)≥εdi(t)下,该种群是持续生存的。  相似文献   

新品种玉米试种结果简评报告     

郭团玉  陈洪 《宁德师专学报(自然科学版)》2005,17(2):146-148

试验种植玉米新品种，并依照《国家鲜食玉米记载项目和标准(试行)》和《鲜食玉米感官等级指标》全程观察各品种生长状态及性状，做记录统计分析并评定感官等级，简评玉米品种诸项指标，筛选适合当地种植的优质品种．  相似文献   

浅谈“两个尺度”的问题     

成迅 《泰州职业技术学院学报》2001,1(1):73-75

马克思关于“美的规律”的提法是马克思美学理论中的一段极为重要的论述,然而对于其中“内在的尺度”究属谁的尺度却众说纷纭,本从比较各家译入手,指出问题的症结在于中译词和德原词义不完全对等上,根据中译词词义,则理解为“物种的尺度”和“人的尺度”均无不可,但根据德词义的特定含义,则“内在尺度”只能理解为“物种的尺度”。  相似文献   

赣南师范学院(黄金校区)访花昆虫物种多样性研究     

徐家生  王茜 《赣南师范学院学报》2012,33(3):120-124

为了解赣南师范学院黄金校区访花昆虫种类,笔者于2010年10月-2011年10月开花期间在校园内采用随机取样和系统取样法,以网捕和手捕方式采集访花昆虫并进行鉴定.结果表明:师院校园共有访花昆虫135种,分属于7目,39科.从目级分类阶元物种数量水平上分析,鳞翅目>膜翅目>鞘翅目>双翅目>半翅目>蜻蜓目>同翅目,其中优势访花昆虫种类为意大利蜜蜂(Apis mellifera)、黑带食蚜蝇(Episyrphus balteatus)和异色瓢虫(Harmonia axyidis).  相似文献   

Hydrogen peroxide functions as a secondary messenger for brassinosteroids-induced CO2 assimilation and carbohydrate metabolism in Cucumis sativus     

Yu-ping Jiang  Fei Cheng  Yan-hong Zhou  Xiao-jian Xia  Wei-hua Mao  Kai Shi  Zhi-xiang Chen  Jing-quan Yu 《Journal of Zhejiang University. Science. B》2012,13(10):811-823

  相似文献   

Factors Influencing Schoolchildren's Responses to a Questionnaire in Wildlife Conservation Education     

Jean-Marie Ballouard  Stephen J. Mullin  Rastko Ajtic  José Carlos Brito  El Hassan ElMouden  Mehmet Erdogan 《International Journal of Science Education》2013,35(3):469-483

Questionnaires are important tools for assessing attitudes regarding conservation issues. However, they are not easily comparable and their reliability has been insufficiently assessed. We examined factors influencing responses to open- and closed-ended questions about animal conservation to more than 600 schoolchildren (9 years old on average). We analysed the level of understanding, controllable (e.g. sample size) and less controllable factors (e.g. affectivity). Most children responded appropriately to the questions, but subtle changes in the phrasing influenced the answers. Affectivity towards endearing species and spontaneity also influenced the responses whereas small sample sizes (～50 children) provided relatively stable patterns. Overall, we suggest that standardization of questionnaires administered over large spatial and time scales is needed to accurately assess children's attitudes towards conservation issues.  相似文献   

一类具有相互干扰的功能反应捕食系统的捕获分析     

吴亭 《闽江学院学报》2013,34(2):16-18

研究一类具有相互干扰功能反应的捕食-食饵系统.对正平衡点的局部渐近稳定性和全局稳定进行了详细说明,证明了系统在正平衡点处是全局稳定的,并利用Pontrjagin最大值原理及最优控制理论,得到该系统的最优捕获策略.所得结果改进和推广了相关文献的主要结果.  相似文献   

双桥水库供水工程区草本植物群落物种多样性     

林长松  向红  左经会  廖雯 《六盘水师范高等专科学校学报》2009,21(6):18-21

采用样方法对水城县保华乡双桥水库工程区草本植物群落特征进行了调查研究。结果表明：水库工程区草本植物群落样方中,种密度为6.167×10^4种/hm^2,个体密度为8.067×10^6株/hm^2,主要以禾本科、菊科、唇形科、蝶形花科等科的植物占优势;草本植物优势种群在不同程度上均表现为集群分布;6个样地中,Simpson指数和Shannon指数的平均值分别为0.680和2.170,表明其物种多样性较丰富。  相似文献   

双桥水库供水工程建设区木本植物群落特征     

向红  林长松  左经会  廖雯 《六盘水师范高等专科学校学报》2009,21(6):13-17

采用样方法对六盘水市水城县保华乡拟修建的双桥水库工程区木本植物群落特征进行了调查。结果表明：水库工程区植被型多为亚热带常绿-落叶阔叶混交灌丛林,以桦木科、蝶形花科、壳斗科、蔷薇科、杜鹃花科、藤黄科、忍冬科、漆树科等科的植物占优势;木本植物优势种群在不同程度上均表现为集群分布;所调查的7个样地中,Simpson指数和Shannon指数的平均值分别为0.756和2.630,表明其物种多样性较丰富。  相似文献   

Resistance towards calcium induced bilirubin dependent hemolysis in porcine erythrocytes     

Boh Boon Kim  Saad Tayyab 《Indian journal of clinical biochemistry : IJCB》2008,23(1):17-23

Hemolysis of erythrocytes from human and porcine blood was studied at different calcium chloride (CaCl₂) concentrations (0.04–1.83 mM) and at a constant bilirubin concentration (72 mM). Although, human erythrocytes showed significant hemolysis (64%) at the highest CaCl₂ concentration (1.83 mM) used in this study, remarkable resistance to this phenomenon was observed with porcine erythrocytes as only 11% hemolysis was observed. A similar pattern in the behavior of both human and porcine erythrocytes was observed when parameter such as bilirubin concentration or time of incubation with bilirubin was varied. Other divalent cations such as Mn²⁺, Ba²⁺ and Mg²⁺ were either least effective or ineffective in inducing hemolysis in presence of bilirubin. Serum albumin played a protective role in this phenomenon in a concentration dependent manner, as no hemolysis was observed at a bilirubin/albumin molar ratio of 1:1 or less. Differences in the structural make-up of proteins and lipids in the erythrocyte membranes of the two species may account for their different behavior.  相似文献