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121.
光谱特征是地物的固有属性,分析地物光谱不仅有助于提高地物识别精度,也是定量遥感研究的基础.然而受限于尺度效应,近地空间采集的光谱与遥感像元尺度的光谱往往差异较大.因此,在遥感像元尺度上揭示湿地典型景观地类的光谱特征,将有助于大尺度湿地遥感分类和植被参数反演精度的提高.以华北平原典型的草型湖泊湿地南阳湖为对象,基于EO-... 相似文献
122.
洞庭湖滨湖丘岗地鼠类群落演替 总被引:2,自引:0,他引:2
作者于1992~1995年和2002~2004年,对洞庭湖滨湖丘岗地的鼠类群落结构和生物多样性变化进行了研究.共置鼠夹2 437夹夜,捕鼠7种,共417个个体.结果表明两个时间段捕获的鼠种数不同,分别为7种和5种,捕获率分别为(12.29±7.05)%和(3.05±1.44)%(t=4.26,df=21,p<0.001);两个时间段的优势鼠种不完全相同,东方田鼠和黑线姬鼠为1992~1995年的优势鼠种,社鼠和黑线姬鼠为2002~2005年的优势鼠种;两个时间段的物种多样性指数和优势度指数差异不显著,但均匀性指数差异显著(t=5.433,p<0.05).对两个时间段的鼠类群落相似性指数进行系统聚类分析,将所有年份的群落相似性指数聚类为2类,即1992~1994年聚为一类,2002~2004年聚为一类.结果表明洞庭湖滨湖丘岗地鼠类群落经过10年的演替,已经成为完全不同的群落. 相似文献
123.
陈启瑺 《浙江大学学报(理学版)》1988,15(1):81-87
本文对组成植被种类的生活型谱和叶的性质进行了分析,并与邻近地区作了比较.结果表明,地处亚热带和暖温带过渡区的本区植被,在群落的外貌特征上与暖温带更接近,体现了更多的北亚热带阔叶混交林的性质.通过对群落结构特征的分析,发现次生群落在体现强烈的次生性质的同时,也反映了由亚热带向暖温带过渡的某些特征.笔者认为:作为北亚热带与中亚热带过渡类型的本区植被,因具有更多的阔叶混交林的性质,宜归属于北亚热带常绿与落叶阔叶混交林地带. 相似文献
124.
M. P. Sobolevskaya I. A. Terkina L. S. Buzoleva I. A. Li M. I. Kusaikin N. S. Verigina A. N. Mazeika L. S. Shevchenko Yu. V. Burtseva T. N. Zvyagintseva V. V. Parfenova T. A. Kuznetsova 《Chemistry of Natural Compounds》2006,42(1):82-87
Data on the biological activity of ethylacetate extracts of Lake Baikal streptomycetes were obtained for the first time. The
extracts of isolated actinobacteria of the genus Streptomyces were tested for the presence of compounds that inhibit the growth of pathogenic and conditionally pathogenic microorganisms
and that exhibit a cytotoxic effect on Erlich carcinoma tumor cells. The ability of streptomycetes to produce inhibitors of
enzymes isolated from marine organisms was also investigated. The production of bioactive compounds as a function of medium
composition was given.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 65–69, January–February, 2006. 相似文献
125.
126.
为了研究新疆中部地区伊吾湖嗜盐微生物和细菌视蛋白基因(bop)资源,分离纯化了95株嗜盐和耐盐菌.并从中挑选了10株红色的菌株,采用PCR和TA克隆的方法,扩增出bop基因螺旋C到螺旋G的核心序列,测定了基因的核苷酸序列.基于bop基因序列的同源性比较和系统发育学分析,发现9个序列分布在同一分支下,表明伊吾湖嗜盐菌bop基因具有一定的多样性和明显的自身地域性. 相似文献
127.
通过对新疆博斯腾湖水污染状况的动态分析.得出了博斯腾湖从初期的自由污染阶段到污染水平β=0.5时所需要的时间以及此后博斯腾湖水环境的未来趋势,进而提出加强博斯腾湖水环境保护。使之可持续利用的相关对策. 相似文献
128.
On the horizontal distribution of algal-bloom in Chaohu Lake and its formation process 总被引:2,自引:0,他引:2
Based on the remote sensing images of algae, the present work analyzes the horizontal distribution characteristics of algal blooms in Chaohu Lake, China, which also reveals the frequency of algal blooms under different wind directions. Further, an unstructured-grid, three-dimensional finite-volume coastal ocean model (FVCOM) is applied to investigate the wind-induced currents and the transport pro- cess to explain the reason why algal blooms occur at the detected places. We first deduce the primary distribution of biomass from overlaid satellite images, and explain the formation mechanism by analyzing the pollution sources, and simulating the flow field and transportation process under prevailing wind over Chaohu Lake. And then, we consider the adjustment action of the wind on the corresponding day and develop a two-time scale approach to describe the whole formation process of algae horizontal distribution in Chaohu Lake. That is, on the longer time scale, i.e., during bloom season, prevailing wind determines the primary distribution of biomass by inducing the characteristic flow field; on the shorter time scale, i.e., on the day when bloom occurs, the wind force adjusts the primary distribution of biomass to form the final distribution of algal bloom. 相似文献
129.
130.
A fractional steps technique for the numerical solution of the shallow water equations is applied to study the water velocity in Lake Mariut, its concentration and the distribution of the temperature along it. Lake Mariut is considering the most productive natural systems in Egypt. The current configuration of this lake is changing rapidly, due to people’s activities and natural processes. Most of its water supply comes from polluted agricultural drains. Several problems affect the conservation of the Lake Mariut, mainly pollution, land reclamation, intensive aquatic vegetation, over fishing and coastal erosion. The shallow water equations for this lake are discretized on a fixed grid and time stepped with the fractional steps method, where the Riemann invariants of the equations are interpolated at each time step along the characteristics of the equations using a cubic spline interpolation. The method is efficient and simple, since it evolves the equations without the iterative steps involved in the multi-dimensional interpolation problem. The absence of iterative steps in the present technique makes it very suitable for the problems in which small time steps and grid sizes are required and the simplicity of the method makes it very suitable for parallel computer. Therefore, the method provides numerical algorithms which are more efficient than other classical schemes. 相似文献