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301.
Measurement of ice velocities of the Antarctic glaciers is very important for studies on Antarctic ice and snow mass balance. The polar area environmental change and its influences on the global environment. Conventional methods may be used for measuring the ice velocities, but they suffer from severe weather conditions in the Polar areas. Use of satellite multi-spectral and muki-temporal images makes it easier to measure the velocities of the glacier movements. This paper discusses a new method for monitoring the glacial change by means of multi-temporal satellite images. Temporal remotely sensed images in the Ingrid Christensen coast were processed with respect to geometric rectification, registration and overlay, The average ice velocities of the Polar Record Glacier and the Dark Glacier were then calculated, with the changing characteristics analyzed and evaluated. The advantages of the method reported here include promise of all-weather operation and potentials of dynamic monitoring through suitabl 相似文献
302.
Zhi-YingHuo 《中国天文和天体物理学报》2002,2(2):112-116
1 INTRODUCTION In the hierarchical clustering model, massive objects form by gravitational aggregation oflower-mass objects, and the disks in spiral galaxies like our Galaxy form by a late accretionof gas from an extended reservoir around the galactic halos. According to this scenario, spiralgalaxies are still growing at present. At the virial temperature of galactic halos, T r.-' io5 ?i06 K, the dominant cooling mech-anism is X-ray bremsstrahlung. If the cooling rate is significant, the… 相似文献
303.
Zhou Chenglong Yang Fan Huo Wen Pan Honglin Meng Lu Mamtimin Ali Li Huoqing Yang Xinghua 《Theoretical and Applied Climatology》2020,140(3):1071-1080
Theoretical and Applied Climatology - Air density strongly constrains the characteristics of an airflow and the resulting flow of sand and therefore, it should not be neglected in sand transport... 相似文献
304.
Phosphorus distribution in the sediments of a shallow eutrophic lake,Lake Chaohu,China 总被引:8,自引:5,他引:3
Fengyu Zan Shouliang Huo Beidou Xi Qingqin Li Haiqing Liao Jingtian Zhang 《Environmental Earth Sciences》2011,62(8):1643-1653
In this study, the sediment profiles of total phosphorus (TP), inorganic phosphorus (Pi), organic phosphorus (Po), C/P and N/P were used to investigate time-dependent P distribution changes in Lake Chaohu. The characteristics of Pi and Po fractions in the surface sediments were studied and the difference between east and west lake region was also discussed.
The Pi and Po contents displayed a clear gradient from east to west in sediments of Lake Chaohu, and the Po/P ratios were lower in sediments with industrial and urban pollution sources input in west lake region. The study indicated
that different sediments area had diverse concentrations and distributions of Po fractions due to their different drainage basin and pollution sources. The profile distribution of the C/P and N/P ratios
decreased with increasing depths and stayed relatively constant ratios at the depths of 15–30 cm. The C/P and N/P ratios were
always below Redfield ratios in sediment profile, indicating P enrichment but likely due to the preferential loss of carbon
in respect to phosphorus. The rank order of Pi-fractions extracted was HCl-Pi > NaOH-Pi > NaHCO3-Pi in surface sediments. The relative distribution of NaHCO3-Pi and HCl-Pi was in agreement with the trophic conditions of the regions studied. Among the sequentially extracted Po forms, the rank order of Po fractions was residual Po > HCl-Po > fulvic acid-P > humic acid-P > NaHCO3-Po, with mean relative proportion of 5.4:3.4:2.2:1.1:1.0. 相似文献
305.
306.
LU Yongzhong ZHANG Xuecheng 《中国海洋大学学报(英文版)》2006,5(1):67-70
In transgenic process, a foreign gene can be integrated in the host genome in two directions, which may influence its expression. In order to study the effects of insertal orientation, the gfp reporter gene was inserted in the isiAB locus of Synechococcus sp.PCC7942 in different directions, and the GFP expression levels and the growth of the transgenic algae were compared. It was showed that the gfp gene could express in each direction, and no significant difference was detected on algal growth and GFP expression levels between the two recombinant algae. 相似文献
307.
我国土壤侵蚀与地理环境的关系 总被引:9,自引:2,他引:7
本文论述我国土壤侵蚀类型与自然地带性和非地带性因素的关系,分析影响侵蚀强度时空分布和侵蚀泥沙输移的环境因素及流域条件。 相似文献
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以陕西神府煤炭资源开采密集区为试验区,利用高分辨率遥感影像特征(色调或色彩,既波谱特征)和空间特征(形状、大小、阴影、纹理、图形、位置和布局),分析了矿山开发过程中所涉及的不同地物信息识别方法,据此建立了煤炭资源开发状况遥感判定标志.根据制定的煤炭资源开发状况判读标志,在试验区解译煤矿46处,其中露天矿山18处,硐采矿山28处,并对全部解译煤矿进行了野外实地验证.经统计,全部46处露天和硐采煤矿的开采位置及开采状态判断准确率较高.近年来由于资源整合,多家企业硐口的开采位置和开采状态都发生明显的变化,因此该煤炭信息判读标准体系的建立对煤矿生产状况调查及维护矿业秩序具有重要意义. 相似文献