一类时滞偏生态模型的振动性

研究一类时滞偏生态模型解的振动性 ,利用平均法 ,通过使用偏泛函微分方程上下解思想和泛函微分方程振动性理论 ,获得了其解的非负性和关于正平衡态振动的充分条件 .     

浙江西天目山天然林及银杏种群考察报告

在完成国内多处同类型研究的基础上 ,笔者对西天目山双清溪沟谷天然林及其银杏进行了专题考察 ,所获第一手资料包括 :双清溪森林古道样带式路线考察立木分布平面图 ;天目山双清溪天然林中银杏及伴生树种调查总表 ;双清溪天然林中银杏种群调查明细表 ;“5代同堂银杏”的树木形态学调查研究 ;禅源寺古森林群落的成分、结构及性质考察等。在充分分析的基础上作者认为 ,双清溪天然林原应属於典型“落叶与常绿阔叶混交林”群落 ,现已进入“针阔叶、落叶与常绿阔叶混交林”演替阶段。该演替系人为干扰下的一种“偏途演替”。银杏种群参与了演替和历史发展的全过程 ,因此 ,它们应该是野生的。“5代同堂银杏”建议正名为“无性系多代同株银杏”比较恰当。禅源寺古森林群落是双清溪沟谷天然林的延伸和残余部分 ,可简称为“禅源寺古森林残存群落”。     

一类与单种群模型有关的非线性泛函微分方程解的振荡性

给出了一类一阶非线性泛函微分方程解的振荡性的充分性判据,并用例子说明了用线性化方程的振荡性判据去给出非线性方程的振荡性的判据有时是错误的。同时,得到了时滞的单种群方程的解的振荡性的一些充分性判据。     

动态聚类在抽样调查中的应用

将动态聚类分析应用于抽样调查方案的总体分组。其要点是:首先将原始数据标准化并进行初始分类;然后根据分类函数进行批修改;最后通过 A 检验得到最优分组。这一方法已在实际抽样设计中成功地运用,并取得了满意的效果。     

小麦个体性状的选择与提高群体生产力关系的研究

本文研究了在少竞争和竞争环境下小麦个体表现和群体表现的关系。结果表明,所考察的40个性状都随密度的变化而变化,不同性状的稳定性不同。相关分析和灰色关联分析结果基本一致,得到一些对群体产量作用较大的性状,他们大多又是稳定或较稳定性状,可做为早代产量选择的主要指标。这些对群体产量作用较大的性状分别属于生育期(A)、生理(B)、产量(C)和形态(D)性状群,低密度下这四个性状群与中、高密度群体产量的典范相关系数大小顺序都是B>D>A>C,生理性状群与群体产量的关系最为密切。稀植下所有农艺性状对密植群体产量逐步回归分析的最终入选性状是每穗粒重和单株有效穗数,再次证明:高产育种在保证适宜亩穗数的前提下,主攻每穗粒重的方向是必要的和正确的。     

Differential basal synthesis of Hsp70/Hsc70 contributes to interindividual variation in Hsp70/Hsc70 inducibility

The source of intraspecies variation in the expression of heat shock proteins (HSPs) remains unresolved but could shed light on differential stress tolerance and disease susceptibility. This study investigated the influence of variable basal HSP synthesis on differential inducibility of HSP synthesis. Basal and heat-induced synthesis of the major HSP families in peripheral blood monocytes from healthy donors (n=42) were analysed using biometabolic labelling and densitometry. Basal Hsp70/Hsc70 synthesis and percentage induction of Hsp70/Hsc70 synthesis were significantly correlated (r=−0.57, p<0.0001), and described most accurately by an exponential decay equation (R=0.68, R²=0.46). This regression equation suggests that increasing levels of basal Hsp70/Hsc70 synthesis are accompanied byan exponential decrease in the percentage induction of Hsp70/Hsc70 synthesis. The model fits data from European and non-European population groups independently, although both coefficients in the regression equation were larger for non-Europeans. This implies population group as an additional factor influencing differential HSP expression. The differential inducibility of Hsp70/Hsc70 due to variable basal synthesis of Hsp70/Hsc70 and based upon population group may contribute to differential stress tolerance or disease susceptibility. Received 27 March 2000; received after revision 19 June 2000; accepted 20 June 2000     

名义尺度总体的共轭先验分布中参数的确定

本文主要就几种情况讨论了名义尺度总体的共轭先验分布中参数的确定问题．     

一种随机微粒群混合算法求解约束优化问题

将微粒群算法（Particle Swarm Optimization,PSO）与随机优化方法-Alopex算法相结合,提出一种随机微粒群混合算法（APSO）求解约束优化问题。该算法使PSO算法中微粒的飞行速度无记忆性,结合Alopex算法重新生成停止进化微粒的位置;采用双群体搜索机制,一个群体保存具有可行解的微粒,用APSO算法使微粒逐步搜索到最优解,另一个群体保存具有不可行解的微粒,并且可行解群体以一定的概率接受性能较优的不可行解微粒,这种简单的群体多样性机制使微粒能够快速、准确地找到位于约束边界上或附近的最优解。结果表明该算法寻优性能优良且具有较好的稳定性。     

一种基于混合差分策略的改进差分进化算法

对启发式优化算法中的差分进化算法进行改进,在进化过程中并行交叉采用DE/rand/1/exp和DE/best/1/exp差分策略,应用聚集度因子进行种群重构,缩小了种群重构后的搜索范围,有效避免了种群重构的随机性.仿真结果表明,改进算法与使用单一差分策略的差分进化算法及PSO算法相比,寻优能力得到了显著提高.     

Reconstruction of linkage maps in the distorted segregation populations of backcross, doubled haploid and recombinant inbred lines

Non-Mendelian segregation of markers, known as distorted segregation, is a common biological phenomenon. Although segregation distortion affects the estimation of map distances and the results of quantitative trait loci (QTL) mapping, the effects of distorted markers are often ignored in the construction of linkage maps and in QTL mapping. Recently, we have developed a multipoint method via a Hidden Markov chain method to reconstruct linkage maps in an F2 population that corrects for bias of map distances between distorted markers. In this article, the method is extended to cover backcross, doubled haploid and recombinant inbred line (RIL) populations. The results from simulated experiments show that: (1) the degree that two linked segregation distortion loci (SDL) affect the estimation of map distances increases as SDL heritability and interval length between adjacent markers increase, whereas sample size has little effect on the bias; (2) two linked SDL result in the underesti- mation of linkage distances for most cases, overestimation for an additive model with opposite additive effects, and unbiased estimation for an epistatic model with negative additive-by-additive effects; (3) the proposed method can obtain the unbiased estimation of linkage distance. This new method was applied to a rice RIL population with severely distorted segregation to reconstruct the linkage maps, and a bootstrap method was used to obtain 95% confidence intervals of map distances. The results from real data analysis further demonstrate the utility of our method, which provides a foundation for the inheritance analysis of quantitative and viability traits.