Electromagnetic induction in thin sheets: integral equations and model studies in two dimensions     

U. Schmucker 《Geophysical Journal International》1995,121(1):173-190

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Multipolar elastic fields in homogeneous isotropic media by higher-order ray approximations     

V. Vavry&#;uk  K. Yomogida 《Geophysical Journal International》1995,121(3):925-932

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An analytical solution of the elastodynamic equations along the axis of a circular fault     

M. Cara  M. Bour 《Geophysical Journal International》1995,123(2):373-390

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Sediment yields and sources in a welsh upland lake-catchment during the past 800 years     

J. A. Dearing 《地球表面变化过程与地形》1992,17(1):1-22

Estimates of suspended sediment yield over the past 800 years have been derived from a whole-basin study of lake sediments in Llyn Geirionydd, North Wales. Magnetic and physical sediment properties were used to correlate a suite of cores to a master chronology based on ²¹⁰Pb and ¹⁴C dates. The sources of sediment within the catchment were identified by comparing the magnetic and heavy metal properties of sediments, soils, and stream sediments. Mean suspended sediment yields range from 6 to 18 t km^?2 yr^?1 with high yields in the periods 1765-1830 and 1903-1985 corresponding to mining activities in the catchment. The impact of earlier deforestation, agricultural expansion, or climatic change on sediment yields is low, although there is evidence that agricultural activities increased levels of peak stream discharge. Afforestation in the 20th century does not appear to have significantly increased sediment yield. Sediment sources have remained fairly constant through time; they appear to be widespread and dominated by stream channel sides rather than point sources, except during the mining phases when spoil material has dominated the sediment load. Sediment loads to the lake today are still dominated by sediment derived from unvegetated spoil heaps.  相似文献   

一个考虑地形影响的三维中尺度Monte-Carlo多源模式   总被引：3，自引：0，他引：3       下载免费PDF全文

邓玉珍  雷孝恩  田瑞明 《气象学报》1993,51(2):139-147

本文设计了一个考虑地形、湍流统计量垂直非均匀和非平稳过程影响的三维中尺度Monte-Carlo多源模式。模式模拟了珠海地区大气SO_2浓度时空分布,很好地揭示了由海陆风和山谷风控制下浓度的日变化规律,计算与实测浓度之间平均比值为0.94±0.2388,其结果是令人满意的。本模式具有概念清楚,没有作人为的特别假设和数值解平流扩散方程时出现的伪扩散问题,更能反映湍流扩散本身具有随机性这一本质的优点。  相似文献   

古里雅冰帽中化学成分的空间变化   总被引：15，自引：6，他引：15  

李月芳  姚檀栋 《冰川冻土》1993,15(3):467-473

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位场广义线性综合反演系统的建立     

张贵宾  申宁华  王喜臣  王华啸 《吉林大学学报(地球科学版)》1993,(2)

以BG理论为基础,首先在重磁异常线性反演中将该理论与吉洪诺夫正则化方法相结合求解地下密度源(或磁源)分布及质心(或磁质心)位置;在重磁非线性反演中结合应用正则化方法和马奎特思想给出一种确定地下密度(或磁性)界面的稳定迭代算法:正则—马奎特法其次研究一种综合多和磁两种异常联合反演既是磁界面也是密度界面的方法。最后,以判断重磁异常是否同源的对应分析为先导,将上述方法综合于一起建立了重磁异常广义线性人机交互式综合反演系统。实际地区的应用已取得较好效果。  相似文献   

The influence of meteorology on clouds at Kleiner Feldberg   总被引：1，自引：0，他引：1  

P. Winkler  W. Wobrock  R. N. Colvile  D. Schell 《Journal of Atmospheric Chemistry》1994,19(1-2):37-58

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蛇绿岩研究的进展   总被引：12，自引：0，他引：12  

张旗 《地学前缘》1994,(Z1)

近几年蛇绿岩的研究已取得显著的进展，主要反映在下述几个方面：１．对于蛇绿岩的概念已有了新的认识，蛇绿岩代表古代的大洋岩石圈碎片，但并非正常的大洋岩石圈；２．关于蛇绿岩的多样性已经提出了许多不同的见解，最近有关特提斯与环太平洋蛇绿岩的对比研究使许多作者得出结论，它们具有不同的特征；３．蛇绿岩源区的研究表明，蛇绿岩并非唯一地来自亏损的软流圈地幔，不同地幔端元之间的混合以及来自陆壳物质的混染作用也是常见的现象；４．早元古代蛇绿岩的发现。预期９０年代，在蛇绿岩的多样性、地幔岩部分熔融、岩浆来源、蛇绿岩的侵位机制以及蛇绿岩与高压变质作用等方面将取得长足的进展．  相似文献   

Stable isotopes reveal varying water sources of Caragana microphylla in a desert-oasis ecotone near the Badain Jaran Desert     

Hai Zhou  WenZhi Zhao  ZhiBin He  Heng Ren 《寒旱区科学》2018,10(6):458-467

Understanding the variation in a plant's water sources is critical to understanding hydrological processes in water-limited environments. Here, we measured the stable-isotope ratios(δ18 O) of xylem water of Caragana microphylla, precipitation,soil water from different depths, and groundwater to quantitatively analyze the proportion of water sources for the shrub.We found that the water sources of C. microphylla differed with the plant's ages and the seasons. The main water source for young shrubs was upper-soil water, and it showed significant changes with seasonal precipitation inputs. In summer,the proportion contributed by shallow water was significantly increased with increased precipitation inputs. Then, the contribution from shallow-soil water decreased with the decline in precipitation input in spring and autumn. However, the adult shrubs resorted to deep-soil layers and groundwater as the main water sources during the whole growing season and showed much less seasonal variation. We conclude that the main water source of the young shrubs was upper-soil water and was controlled by precipitation inputs. However, once the shrub gradually grew up and the roots reached sufficient depth, the main water sources change from the upper-soil layer recharged by precipitation to deep-soil water and groundwater, which were relatively stable and abundant in the desert ecosystem. These results also suggest that desert shrubs may be able to switch their main water sources to deep and reliable water sources as their age increases, and this adjustment to water availability carries significant importance for their acclimation to the desert habitat.  相似文献