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261.
本选用中国冰川目录数据库中的青藏高原内陆水系冰川粒雪线、中值高度和地理坐标资料,利用计算机绘图方法,绘制出冰川粒支线、中值高度在空间的变化趋势,以便全面认识该地区的冰川发育特征。 相似文献
262.
263.
东北地区中尺度对流复合体的卫星云图特征 总被引:5,自引:0,他引:5
通过10年(1983-1992年)卫星云图资料的分析,综合归纳了东北地区中尺度对流复合体(NMCC)的基本特征及其发展演变过程,由于受地理条件的影响,NMCC与美国大平原以及我国西北和华北平原上的MCC有明显差别,作为一类特殊的对流性天气系统,NMCC与一般中尺度对流云图特征有明显差异。 相似文献
264.
265.
横断山不同成因类型花岗岩类岩石中黑云母的标型特征 总被引:8,自引:5,他引:8
本文研究了横断山区不同成因类型花岗岩类岩石中黑云母的化学成分、微量元素、结构和物理性质等。结合花岗岩类岩石的成因类型,将黑云母分为三个亚种:富镁黑云母(MF=1.3—1.5)、镁黑云母(MF=1—1.3)和富铁黑云母(MF=0.5-1)。 相似文献
266.
267.
本文详细地分析了用数字化仪和激光扫描仪对模拟加速度记录进行数字化时所产生的误差及消除这些误差的方法,并开发了相关处理软件。数字化误差由数字化设备的系统误差和读数员在操作过程中的随机误差迭加而成,随机数字化误差是具有各态历经性质的、其振幅按高斯规律分布的平稳随机过程。利用激光扫描仪做强震记录数字化,工作效率很高。本文给出了激光扫描仪分析处理软件和消除数字化噪声实例。 相似文献
268.
Barchans of Minqin: Morphometry 总被引:2,自引:0,他引:2
The barchans on the border of Minqin oasis, China, were surveyed. Our data reconfirmed that the height of slipface is proportional to the width of horns and the baseline can be roughly described by parts of an ellipse and a parabola. We attempted to study dune geomorphology using the theory of differential geometry. The geometrical characteristics of the brink can be quantitatively determined by its curvature and torsion. 相似文献
269.
Based on the tested data of pressure and vitrinite reflectance of some wells in sedimentary basins, abnormal high pressure
is regarded as not the only factor to retard the increase of vitrinite reflectance (R
o). Apart from the types of the organic matter, the physical environment (temperature and pressure) and chemical environment
(fluid composition and inorganic elements) will result in the abnormal vitrinite reflectance values in the sedimentary basins.
This paper tested trace elements and vitrinite reflectance data from the the abnormal high pressure and normal pressure strata
profiles, respectively, and found that the acidic and lower salinity starta are favorable for the increase of R
o. By discussing the corresponding relationship between the contents of some trace elements in the mudstone and the vitrinite
reflectance values, the typical trace elements were found to suppress and/or catalyze the vitrinite reflectance of organic
matter, while the elements of Ca, Mn, Sr, B, Ba and P may result in the retardation of R
o. However, elements of Fe, Co, Zn, Ni and Rb may catalyze the organic matter maturation. This study is conductive to the organic
maturation correction, oil and gas assessment and thermal history reconstruction by the paleothermometry.
Translated from Acta Geologica Sinica, 2006, 80(11): 1760–1769 [译自: 地质学报] 相似文献
270.
Crustacean zooplankton distribution patterns and their biomass as related to trophic indicators of 29 shallow subtropical lakes 总被引:3,自引:0,他引:3
A comparative limnological study was carried out to present a snapshot of crustacean zooplankton communities and their relations to environmental factors to test whether there is a consistent relationship between crustacean biomass and trophic indicators among lake groups with similar trophic conditions. The study lakes showed a wide range of trophic status, with total phosphorus (TP) ranging from 0.008 to 1.448 mg L−1, and chlorophyll a from 0.7 to 146.1 μg L−1, respectively. About 38 species of Crustacea were found, of which Cladocera were represented by 25 taxa (20 genera), and Copepoda by 13 taxa (11 genera). The most common and dominant species were Bosmina coregoni, Moina micrura, Diaphanosoma brachyurum, Cyclops vicinus, Thermocyclops taihokuensis, Mesocyclops notius and Sinocalanus dorrii. Daphnia was rare in abundance. Canonical correspondence analysis showed that except for four species (D. hyalina, S. dorrii, C. vicinus and M. micrura), almost all the dominant species had the same preference for environmental factors. Temperature, predatory cyclopoids and planktivorous fishes seem to be the key factors determining species distribution. TP was a relatively better trophic indicator than chlorophyll a to predict crustacean biomass. Within the three groups of lakes, however, there was no consistent relationship between crustacean biomass and trophic indicators. The possible reason might be that top-down and bottom-up control on crustaceans vary with lake trophic state. The lack of significant negative correlation between crustacean biomass and chlorophyll a suggests that there was little control of phytoplankton biomass by macrozooplankton in these shallow subtropical lakes. 相似文献