首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 140 毫秒
1.
利用扫描电镜对木犀属美丽木犀和布克木犀的花粉形态进行了观察与测量.结果显示:美丽木犀和布克木犀花粉在P/E值、外壁纹饰、萌发沟方面表现出一定的相似性,表现为花粉为近球形,外壁具有网状纹饰,三孔沟萌发;在花粉大小(P、E)、沟长(L)、沟深(D)、网眼大小等方面表现一定的差异性.通过对布克木犀、美丽木犀、山桂花花粉形态的比较,推测花粉大小、P/E值是判断其杂交起源的依据之一.  相似文献   

2.
蜡梅品种花粉粒扫描电镜特征的分类研究   总被引:2,自引:0,他引:2  
应用扫描电镜对蜡梅3个品种群共21个品种的花粉粒形态特征进行了观察和比较,对观测结果进行了主成分分析与聚类分析。结果表明:蜡梅花粉粒为中等大小,近扁球形至圆球形;蜡梅花粉外壁纹饰可分为蠕虫状和拟蠕虫状两个类型;蜡梅品种间花粉形态比较类似,但在纹饰细微特征、花粉粒大小、萌发沟长宽度等方面存在一定差异,可作为区分品种的辅助依据;花粉形态聚类分析结果与传统形态分类结果存在差异,花粉形态与内被片和中被片颜色并无直接关联。  相似文献   

3.
国槐及其变种、变型花粉形态的比较研究   总被引:2,自引:0,他引:2  
利用扫描电镜对国槐(Sophova japonica L.)及其变种、变型的花粉形态进行了观察,描述了其花粉形态特征.通过比较研究表明花粉具有种内一致性,均为长球形,具3条萌发沟;花粉大小和表面纹饰的形态结构特征表现出种、变种和变异之间存在差异,可以作为分类依据.  相似文献   

4.
胡枝子属与米口袋属花粉亚显微形态特征的比较研究   总被引:2,自引:0,他引:2  
报道了山东胡枝子属6种植物花粉与米口袋属4种植物花粉的亚显微形态特征,并对两属进行了比较分析.它们韵花粉从赤道面观均呈近长球形,极面观呈三裂圆形;具三条萌发沟;花粉粒的大小,极轴长27.2~19.5μm,赤道轴宽21.3~11.8μm.两属植物花粉的大小、表面纹饰、花粉粒萌发沟的沟裂宽度均有明显差别。研究结果表明,胡枝子属和米口袋属花粉的亚显微形态特征支持传统分类中的属、种级水平的分类。  相似文献   

5.
刺槐属(Robinia)植物花粉形态研究及其分类学意义   总被引:1,自引:0,他引:1  
利用扫描电子显微镜对刺槐属(Robinia)植物的花粉进行了观察和研究,报道了花粉形态特征,探讨了花粉形态特征的分类学意义.结果表明刺槐属花粉具有属内一致性,均为长球形,具3条萌发沟;其花粉大小和表面纹饰的形态结构特征表现出种间,种与变种、变型之间的差异,可以作为分类依据,同时给出了花粉分类检索表.  相似文献   

6.
杨德奎 《山东科学》2011,24(2):21-23
应用扫描电子显微镜对百合属(Lilium L.)植物3种1变种的花粉形态进行了观察研究。结果显示:花粉形态皆呈椭圆体,具单沟萌发器官。花粉粒在大小、外壁雕纹等性状上种间差异显著。  相似文献   

7.
本文对中国苦苣苔科长蒴苣苔属8种花粉形态进行了扫描电镜观察。花粉均具三拟孔沟,形状为近长球形,极面观为三裂圆形,赤道面观为椭圆形,花粉沟相当长且相当窄,内陷,沟膜有颗粒突起。研究表明:长蒴苣苔属各种类花粉在形状和花粉沟等主要特征上具有很好的一致性,但在表面纹饰上有一定的区别。  相似文献   

8.
报道了利用扫描电子显微镜对葱属(Allium L.)4种植物花粉形态的研究结果.结果显示,该属花粉为长球形和超长球形,具单沟,外壁雕纹均为脑纹状,表现出属的一致性,但其花粉形状、条纹突出程度、条纹分布以及孔穴数量均表现出种间差异.因此花粉形态特征可作为葱属植物种间分类的依据之一.  相似文献   

9.
用扫描电镜观察研究了产地不同的七珠小花草玉梅花粉形态,发现小花草玉梅花粉在萌发孔类型上存在着明显的变异,萌发孔类型有三沟、散沟和散孔三种,在花粉形状上也有一定的变异。通过讨论小花草玉梅花粉变异及其与系统演化的关系,最后总结出小花草玉梅花粉萌发孔类型的系统演化趋势,即三沟→散沟→散孔。  相似文献   

10.
作者用扫描电镜研究了七株黄芪及其变种的花粉形态.该七株个体的花粉形态归为花粉粒长球形、大小为24.1×14.8μm,萌发沟细窄、沟膜不伸展和花粉粒球形、大小为18.7×17.1μm、萌发沟较宽、沟膜伸展等两类,而黄芪和其变种各自都包含了这两种花粉类型.黄芪的两种花粉类型与子房被毛与否有一定的联系.此外,本文讨论了花粉学与分类学之间相关性的重要性.  相似文献   

11.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

12.
Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to  相似文献   

13.
Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications (up to 574.8 km/ h test speeds or 380 km/h commercial speeds) in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.  相似文献   

14.
15.
Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.  相似文献   

16.
为了有助于提高英文爱好者的个人情操、文化素养和学习兴趣,以及专业人员对英语学习和研究进行多途径的探索,本文通过一些精选诗歌的引证和分析,着重论述了喻类修辞法在英文诗歌中的运用其及效果。  相似文献   

17.
Tennessee Williams is considered as one of the most important American playwrights since World War II.The Glass Menagerie is his first successful drama,which describes a tragic situation of family and means to say that Man is unable to change the miserable life,no matter whatever means he try,This essay focuses on the analysis of the arrangement of the four main characters:Laura.Amanda,Jim and Tom to reveal the theme.Laura is fragile.Amanda is brave.Jim is vital.Tom is sensible.And all of them develop and try the different means to struggle against life,but fail tragically.With the evidence,the paper comes to conclusion naturally that Man is unable to change the miserable life,and he dooms to fail.  相似文献   

18.
The aim of this study is to investigate the diversity of Retama raetam root-nodule bacteria isolated from arid regions of Tunisia. Twelve isolates, chosen as representative for different 16S rRNA gene patterns, were characterized by 16S rRNA gene sequencing and phenotypic analysis. Isolates were assigned to Sinorhizobium, Rhizobium and Agrobacterium. Symbiotic properties of Sinorhizobium and Rhizobium isolates showed a large diversity in their capacity to infect their host plant and fix atmospheric nitrogen. Strain RK 22 identified as Rhizobium was the most effective isolate.  相似文献   

19.
正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme  相似文献   

20.
介绍了WiMAX与Wi-Fi两种无线宽带接入技术,并对两者之间的关系及相互之间的影响做了对比及分析,并对WiMAX的关键技术进行了详细说明,最后对两者的联合组网方式做了简单的探讨。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号