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1.
首先介绍了面向对象的软件分析建模的重要性;并在分析比较目前流行的几种面向对象分析建模策略的基础上,着重介绍了在开发青鸟系统系列工具中采用的一种基于面向对象技术的分析建模策略;对分析建模过程中涉及的一些关键问题进行了探讨.  相似文献   
2.
The green June beetle (Cotinis nitida) was observed in northern Virginia for a second and third flight season. The study yielded some results that were consistent with earlier findings, namely that mate-locating beetles were vulnerable to attack by avian predators and matings occurred primarily early in the flight season. Novel findings included the following: (1) blue jays (Cyanocitta cristata) were the major predators, not common grackles (Quiscalus quiscala), (2) some jays appeared to selectively prey on female beetles, (3) competition for mates among male beetles could be so intense that some males attempted to copulate with already mated (unreceptive) females, and (4) the sex ratio of the beetle population feeding on wild blackberries remained near equality late in the flight season despite the fact that the sex ratio of the population of beetles at the emergence site became highly female-biased over time.  相似文献   
3.
歌词的深层隐喻意义已经超出了字面含义,以一种思维认知的形式存在。以歌曲《鸟儿在风中歌唱》为例,阐述歌曲教学中把握歌词映射的重要性,将歌词隐喻认知作为分析声乐作品隐喻思维的重要手段,调动学生积极性,拓展学生隐喻思维,有利于学生正确理解歌曲和个性演唱。  相似文献   
4.
河南信阳南湾水库牌坊鸟岛鸟类调查报告   总被引:1,自引:0,他引:1  
自1986年以来,我们多次对牌坊鸟岛的鸟类进行了调查。目前,现巳查明分布于该岛的鸟类有95种,隶属16目,30科。其中留鸟38种,夏候鸟33种,冬候鸟5种,旅鸟19种。该岛鸟类区系具有东洋种和古北种混杂分布的特点,以东洋种为主。  相似文献   
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6.
Summary A number of migratory bird species have endogenous annual rhythms that regulate the entire annual cycle including the migratory portion. Moreover, captive migrants display inherited migratory activity; this could theoretically also be used by free-living migrants as a time-program for migration. Finally, this heritable migratory activity is oriented in a seasonally appropriate direction even in naive birds. These, characteristics should enable inexperienced migrants isolated from contact with experienced conspecifics to utilize a heritable vector-navigation program to migrate from the breeding grounds to the winter quarters. That is, migrants should reach goal areas they have never experienced by migrating in programmed directions, for as long a period as the genetically fixed time-program for migratory activity induces them to do so. The time-course of migration as established by trapping stations, theoretical influences of environmental variables on migratory programs, and also compensatory behavior and migratory backup measures, are discussed. The present evidence supports the view that a large number of migrants are essentially brought to their wintering areas by vector-navigation systems.  相似文献   
7.
Summary Migratory flights are strongly affected by wind, and birds have developed many adaptations to cope with wind effects. By day, overland migrants at high altitudes may often allow crosswinds to drift their tracks laterally from the preferred heading. In contrast, many birds at low altitude adjust their headings to compensate for drift, and may overcompensate to allow for previous drift. The relative motion of landscape features is probably used to sense drift, at least by day. By night, some overland migrants compensate fully for drift but others do not; no pattern is obvious. Over the sea, compensation is rarely if ever total; wave patterns may allow partial compensation. Other adaptations can include reduction of drift by flying at times and/or altitudes without strong crosswinds. Some birds recognize the need to change course to allow for previous wind displacement, and reorient at least roughly toward the original route or destination. Some juveniles en route to previously-unvisited wintering grounds seem to have this ability, but corroboration is needed. Such reorientation may not require a true navigation ability. However, some birds have unexplained abilities to sense the wind while aloft.  相似文献   
8.
高分辨率遥感影像的应用越来越多,但其高昂的成本让一般项目望而却步.应用软件从Google Earth上下栽已成为获取高空间分辨率影像的有效途径,但因无光谱信息,解译局限较大.选用C4.5算法的决策树方法,对目标为水塘研究的广州市天河区的下载的快鸟数据进行解译,与最大似然分类法和面向对象分类法相比较.结果表明:决策树分类法的分类精度和kappa系数均较高,能利用多源数据,结构简单直观,易于表达和应用;提取小目标地物更有效,数据量相对小.速度较快.  相似文献   
9.
首次对贵州省习水自然保护区鸟类资源的种类、分布及蕴藏量进行了调查和分析,该地区现有鸟类147种隶属于16目36科,其中留鸟91种,夏候鸟32种,冬候鸟17种,旅鸟7种,新分布鸟类3种. 并对该地区的鸟类资源进行了评价与分析.  相似文献   
10.
Embden goose (GEWL) and Barbary duck (DEWL) egg white lysozymes possess different amino acid sequences corresponding to the g-type and c-type, respectively. GEWL was shown to be a better immunogen than DEWL in both rabbits and mice. The antigenicity of the two lysozymes was tested using different technique (i.e. indirect ELISA, inhibition tests and immunoabsorption experiments). Injection of either GEWL or DEWL into rabbits and mice induced both specific antibodies and cross-reacting antibodies. Moreover, anti-GEWL antibodies, in contrast to anti-DEWL antibodies, did not cross-react with hen egg white lysozyme (HEWL), a c-type lysozyme. While the structure of GEWL was not modified after binding to plastic, DEWL was denaturated, but it did keep some native epitopes. It was concluded that g-type and c-type lysozymes, which have different amino acid sequences, exhibit strong common antigenic properties.  相似文献   
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