柑桔红圆蚧与三种寄生蜂相互作用系统的动态研究

本文建立了红圆蚧(Aonidiella aurantii)与3种寄生蜂:盾蚧长缨蚜小蜂(Encarsia citrina)、岭南黄蚜小蜂(Aphytis lingnanensis)和印巴黄蚜小蜂(Aphytis melinus)相互作用的系统模型。按红圆蚧的面积大小分成3种类型,分析了三维系统和四维系统在不同红圆蚧大小分布条件下,系统的动态变化。确定了寄生物共存和相互排斥的边界条件,为红圆蚧的生物防治决策提供理论依据。     

黑缘红瓢虫生物学特性的研究

本文系统地观察和研究了黑缘红瓢虫的形态特征，生活史，生活习性等生物学特性，研究结果表明，黑缘红瓢虫在本地区一年发生一次，以成虫在杂草，石缝中等处越冬，是朝鲜球坚蚧等多种蚧虫的重要天敌之一，主要分布在桃树，梅树等树上，对朝鲜球坚蚧等有较强的控制作用，黑缘红瓢虫主要以幼虫捕食猎物为主，成虫主要起繁殖和扩散作用。     

印巴黄蚜小蜂的引进及其生物学研究

印巴黄蚜小蜂是防治柑桔红圆蚧的优良蜂种,1989年本实验室得到Luck教授的邦助,从美国引进此蜂,以茶长本圆蚧作为替换寄主,在室内饲养了5年,约繁殖了50个世代,并对其个体发育、对寄主的选择与子代性比、发育历期与温度关系等方面进行了研究。与此同时,进行了田间散放试验。本文是这些研究工作的概述。     

利用最近邻体法探求朝鲜球坚蚧在梅树上的分布

根据梅园梅枝表面上10组朝鲜球坚蚧统计的数据，用最近邻体法测定了朝鲜球坚蚧种群在梅枝上的分布，测定结果均为聚集分布。     

梅园朝鲜球坚蚧种群空间格局研究

采用聚集度指标方法对梅园的朝鲜球坚蚧种群空间格局进行初步研究，结果表明朝鲜球坚蚧在梅园中分布是：垂直方向和水平方向均为聚集分布。     

两种寄生物-单种寄主的功能反应研究

本文研究了两种寄生蜂Aphytis sp.and Aphytis melinus在寄主茶长本圆蚧(Abgrallaspis cyanophylli)上的混合寄生效应。结果表明,在混合种群中,两种蜂的攻击效率都减小到单独做功能反应时的1/10。同时,本文首次提出了两种寄生物—单种寄主的功能反应模型,模拟效果较好。     

黑缘红瓢虫生物学特性的研究

本文系统地观察和研究了黑缘红瓢虫的形态特征、生活史、生活习性等生物学特性。研究结果表明 ,黑缘红瓢虫在本地区一年发生一代 ,以成虫在杂草、石缝中等处越冬 ,是朝鲜球坚蚧等多种蚧虫的重要天敌之一。主要分布在桃树、梅树等树上 ,对朝鲜球坚蚧等有较强的控制作用。黑缘红瓢虫主要以幼虫捕食猎物为主 ,成虫主要起繁殖和扩散作用     

利用最近邻体法探求朝鲜球坚蚧在梅树上的分布

根据梅园梅枝表面上10组朝鲜球坚蚧统计的数据,用最近邻体法测定了朝鲜球坚蚧种群在梅枝上的分布,测定结果均为聚集分布.     

如何观察蚧虫生活史

蚧虫是农林业上一种重要的害虫,了解蚧虫生活史对于蚧虫的预测预报以及害虫防治有着十分重要的指导意义。仅由于蚧虫世代重叠,难于辨别世代顺序,且体被蜡质,不显昆虫特征,用肉眼只能看到体表的蚧壳,给生活史观察带来了很大困难,有时由于没有采用正确的方法以及缺乏实践经验,得出的结论往往有些偏差,不够准确。笔者在教学之余,带领林业班学生对竹秆红链蚧、卫予矢尖蚧、蠕须盾蚧、密竹链蚧进行了观察研究,积累了一些经验。现就如何观察蚧虫生活史作一介绍。     

梅园朝鲜球坚蚧种群空间格局研究

采用聚集度指标方法对梅园的朝鲜球坚蚧种群空间格局进行初步研究 ,结果表明朝鲜球坚蚧在梅园中分布是 :垂直方向和水平方向均为聚集分布。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.     

团图为数的图中的闭团贯数

Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.