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281.
To test postglacial population expansion in small arboreal mammals dependent on boreal and subboreal forests, we used complete mitochondrial cytochrome b gene sequences (1140 bases) to investigate the phylogeography of the Eurasian red squirrel (Sciurus vulgaris orientis) on the Hokkaido Island of Japan. This subspecies is common in the boreal and subboreal forests of Hokkaido. We examined 61 specimens from 27 localities in Hokkaido. Phylogenetic relationships among 29 haplotypes found in the Hokkaido populations were not associated with geographic distribution of sampling localities. There were four mitochondrial DNA phylogroups. Phylogeographic analyses support sudden expansion of S. vulgaris orientis from restricted refugium in the southern part of Hokkaido during the last glacial period. The phylogeographic structure of this subspecies directly reflects the boreal and subboreal forest dynamics occurring in Hokkaido.  相似文献   
282.
Calanthe izuinsularis is a rare, beautiful and fragrant orchid endemic to the Izu archipelago. Although it is known that mainland populations of closely related Calanthe species are pollinated by medium- to large-sized bees, it is likely that C. izuinsularis has been forced to alter its floral biology to attract alternative pollinators, as large-sized bees are rarely found on the Izu Islands. Indeed, the unusual floral characteristics of C. izuinsularis, which produces pale flowers that emit a strong and fragrant scent during the night, are considered the adaptation to a moth-pollinator syndrome. As expected, our time-lapse photography using a digital camera revealed that the inflorescences of C. izuinsularis were most frequently visited by nocturnal moths such as Noctuidae, Geometridae and Crambidae, which accounted for 50% of all insect visits (in terms of both the number of frames with captured visitors and the number of times visited). However, our study could not provide evidence of a pollinator shift towards moths because none of the moth species was observed with pollinaria. On the other hand, our study found that the pollinaria of C. izuinsularis could become attached to the mesothorax of the small-sized sweat bee Lasioglossum occidens. Therefore, our study suggests that C. izuinsularis is still somewhat dependent on bee pollination, while the orchid has changed its floral colouration and scent. The occurrence of bee-pollination in C. izuinsularis would provide an explanation for how the natural hybridisation between C. aristulifera, C. discolor and C. izuinsularis can occur.  相似文献   
283.
为分析长沙市城区内不同区域的高层建筑群的局部环境的差异,选取了3个典型的建筑群区域进行测试。为了解住户内部的热湿环境差异,在每个区域选取一典型住户进行室内环境的实测。同时,对各个区域进行红外线测试,绘制红外线温度图来分析城区的热岛效应。测试分析表明,长沙市不同的高层建筑群区域的环境状况差别不大,但位于不同区域的住户室内热湿环境差别较大。经红外线分析可知,长沙市中心城区的热岛强度在6℃以上,相比之下,岳麓山附近热岛效应较弱。  相似文献   
284.
Cool coatings (solar reflective coatings) possess a high total solar reflectance and a high thermal emittance, and they have potential applications in building surfaces, pavements, and oil tanks. By decreasing the accumulation of heat, these coatings can reduce the urban heat island effect to increase thermal comfort and to decrease energy consumption in hot zones. In this work, a cool white coating based on waterborne acrylic was prepared. The reflectance and thermal emittance were measured using an ultraviolet- visible-near-infrared spectrophotometer and the steady- state calorimetric technique, respectively. The cool coating possessed a total solar reflectance of 0.887 and a thermal emittance of 0.85. The linear fitting results indicated that the thickness of the dry film is an important factor that affects the reflectance and that the physical limit of total solar reflectance in practical cool coatings is 0.91. A homemade device developed according to military specification MIL-E-46096C was used to measure insulation temperature differences, and an insulation temperature difference of 29 ℃ was obtained. The above results demonstrated that the cool coating can be applied to buildings.  相似文献   
285.
通过亚洲最大的露天煤矿——平朔安太堡矿10年来的降雨量与临近朔城镇与平鲁区的降雨量分析比较后,证实露天采煤并没有影响到大气降雨,也就没有人们想象中的露天采煤引发的热岛效应现象。  相似文献   
286.
李刚  赵玉新 《系统仿真学报》2007,19(16):3734-3738,3765
在地形表达上不规则三角网应用广泛,实际中用到最多的也是Delaunay三角网剖分算法。针对约束数据域下的Delaunay三角剖分通常不满足DT特性的问题进行了阐述,分析了已有的三种引入附加点的算法,算法主要从几何的角度考虑如何减少附加点的数量,而加入附加点的最终目的在于获得更加真实的地形,因而提出了基于边界特征点提取的约束Delaunay三角剖分算法,算法实质就是在加入特征约束之前提取能够满足可以真实再现地形的所有特征点作为新的特征约束,省去附加点的概念,应用现有的Delaunay三角剖分算法进行构网,保证构建后的地形仍具真实感。  相似文献   
287.
针对阐述煤炭企业综合自动化的现状和存在的问题,介绍工业以太环网的组成、性能和特点,提出煤炭企业综合自动化系统的一般构成形式。通过调查煤炭企业的应用现状,找出影响综合自动化使用效果的关键问题和原因。煤炭企业综合自动化的内容较多,通用性又较差,所以要想在煤炭企业建设一套高效、稳定、简洁的综合自动化系统,必须遵循自上而下的实施原则,即在各个子系统的设计、选型和购置上就必须为综合自动化系统做好准备。如果遵循了自上而下的实施方法,可以加快系统集成的进度,消除信息孤岛,缩短建设周期,降低建设成本。  相似文献   
288.
289.
自西汉中央封建政权对海南岛实行统治之后,中原汉族遗民或出于军事征伐,或为任官贬官,或因经商先后进入该岛。其后历经隋、唐、五代、宋、元、明、清。虽然中央封建政权对海南岛的统治时“紧”时“松”,但汉人迁入却随着历史的推移而不断增多,形成岛上今天占全岛人口85%比例的汉族遗民强大民族群。本文略述其中各时期的汉族移民的发展概貌  相似文献   
290.
The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960-2000 annual precipitation observations at 20 stations in the Beijing region.The results show that:the annual precipitation in the Beijing region possesses the large scale variation character with the linear trend of-1.197/10 yr,which corresponds to a total reduction of 27.82 mm in annual precipitation in the 41 years;the local annual precipitation anomalies(percent of the normal 1960-2000)show a positive center near the urban area,i.e.urban precipitation island(UPI),whose intensity increases with the linear trend of 0.6621%/10 yr,opposite to the interannual trend of large scale precipitation over the Beijing region;changes in the UPI are also associated with the intensity of synoptic processes of precipitation,and when the synoptic processes are strong(wet years),the intensity of UPI strengthens,while the synoptic processes are weak(dry years),and the UPI disappears in the Beijing region.  相似文献   
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