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31.
Detailed examination of China's 1982 census data confirms that the standard of age reporting among the Han Chinese, and among many of the ethnic minorities, is very good. Furthermore the quality of age reporting is unaffected by large variations in levels of literacy which exist between men and women, between young and old, and between rural and urban areas. Much of the credit for the high quality of China's age reporting stems from the distinctive nature of Chinese traditional calendars. However, in the far west of China, in the Xinjiang Autonomous Region, age heaping and age exaggeration are as bad as they are in many other developing countries. The authors show that the poor quality of age reporting in Xinjiang is confined to three of the region's ethnic communities, the Uygur, Kirgiz and Tajik, who appear to neither know, nor care, how old they are. 相似文献
32.
本文记述了发现于辽南复州湾上石炭统太原组的燕海扇类,计5属17种。讨论了Annuliconcha与Paradoxipecten的属征及有关问题。上述发现在东北地区尚属首次。 相似文献
33.
法国是世界测绘强国之一。法国国家测绘局(IGN)是法国测绘的领导机构。本文介绍了IGN的概况,并对IGN大地测量、地图制图、对外服务、研究机构等情况作了较详细的描述。在此基础上对IGN的未来发展特点提出了几点看法。 相似文献
34.
35.
胶莱盆地含金建造地球化学特征 总被引:2,自引:0,他引:2
胶莱盆地蓬家夼金矿床及宋家沟金矿床均赋存于下白垩统莱阳群一段含金建造中,该含金建造由砾岩、含砾砂岩、碳质泥岩及碳酸盐岩等组成,Au100.2~241.0ng/g,Ag1.50~3.73μg/g,Zn560~1021μg/g,Pb356~364μg/g,Cu60~394μg/g,As11.0~25.4μg/g,同时富硫及有机碳。含金建造K-Rb、K-Ba呈正相关,K-Sr、K-Ca不相关,Sr/Ba<1,B、V关系均显示了陆相淡水沉积特征。La/Y-REE组成显示了沉积特征。围岩、矿石及矿石中黄铁矿及磁铁矿的稀土元素分布模式相似,该含金建造是矿源层也是容矿层,是区内重要的成矿地质条件及找矿标志。 相似文献
36.
Origin of a large breccia-vein system in the Sanerlin uranium deposit, southern China: a reinterpretation 总被引:1,自引:0,他引:1
The early Tertiary Sanerlin uranium deposit is located near the southwestern margin of the Chaling-Yongxing pull-apart basin defined by the Chaling-Yongxing and Chenxian-Linwu sinistral strike-slip faults in southern China. The uranium ores are hosted in 15 breccia-vein bodies, which are separately located in the cores of three secondary anticlines of the Upper Permian Dangchong Formation. Individual breccia-vein bodies are composed of fragments of silicified shale and sandstone from the Dangchong Formation, and quartz veinlets as cements. These fragments, together with quartz veins, form a mosaic texture. Hydrothermal pitchblende is the only commercial uranium mineral, mainly occurring as disseminated grains within quartz veins or coating fragments. Other metallic minerals include molybdenite, pyrite, chalcopyrite, galena, sphalerite, and red microcrystalline hematite. Fluid inclusions in quartz veins have homogenization temperatures ranging from 150 to 280 °C, and calculated salinity values between 5.6 and 13.4 wt% NaCl equivalent. Stable isotope analyses show that the mineralizing fluid was characterized by '18O values of -2.2 to +2.6 and 'DH2O values of -134 to -110. These analytical data demonstrate that hydrothermal fluids were mainly derived from formation waters (brines) of the Chaling-Yongxing basin. Fluid overpressuring was caused by an abnormal geothermal gradient and impermeable shales in the deposit area. The geometry, texture, and structure of the breccia-vein system, along with the fluid pressure estimates, suggest that hydraulic fracturing generated the mineralized breccia-vein system. Pitchblende and associated minerals were deposited when gaseous phases were released abruptly from the ore fluids due to the hydraulic fracturing. 相似文献
37.
Peter G. Verity 《Estuaries and Coasts》2002,25(5):944-960
The Skidaway River estuary is a tidally-dominated subtropical estuary in the southeastern USA surrounded by extensiveSpartina salt marshes. Weekly smapling at high and low tide began in 1986 for hydrography, nutrients, chlorophylla, particulate matter, and microbial and plankton biomass and composition; hydrographic and nutrient data during 1986–1996
are reported here. Salinity varied inversely with river discharge and exhibited variability at all time scales but with no
long-term trend. Water temperature typically ranged over 25°C and was without apparent long-term frend. Seasonal cycles in
concentrations of NO3, NH4, PO4, Si(OH)4, and DON were observed, with annual maxima generally occurring in late summer. Superimposed on seasonal cycles, all five
nutrients exhibited steady increases in minimum, mean, and maximum concentrations; mean concentrations increased c. 50–150%
during the decade. Nutrient concentrations were highly correlated with water temperature over the ten-year period, but weakly
related to salinity and discharge. Nutrients were strongly correlated with one another, and the relative ratios among inorganic
nutrients showed little long-term trend. Correlations among temperature and nutrient concentrations exhibited considerable
inter-annual variability. Major spikes in organic and inorganic nutrient concentrations coincided with significant rainfall
events; concentrations increased hyperbolically with rainfall. Although pristine compared to more heavily impacted waterways
primarily outside the region, residential development and population density have been increasing rapidly during the past
15–20 years. Land use is apparently altering nutrient loading over the long-term (months-years), and superimposed on this
are stochastic meteorological events that accelerate these changes over the short term (days-weeks). 相似文献
38.
39.
采用一致的地震震相和台网布局,应用昆明数字地震台网资料,对2002年月1月4日-1月7日的漾濞地震及序列作进一步核定,得出了更精确的地震震源位置,并作出三维空间图。 相似文献
40.
In east Asia, acidic gases derived from fossil fuel combustion have increased in the past decades. On the other hand, the Asian dust, also called Kosa (yellow sand) is transported following windstorms from arid lands in the Asian continent. Many researchers have been interested in the reaction between acidic aerosols and Kosa aerosols as well as the long-range transport of these emissions. To investigate the characteristics of chemical components in precipitation on a long-term basis over Japan, precipitation was sequentially collected from April 1984 to March 1997 at Kanazawa located near the coast of the Sea of Japan. Precipitation samples were collected at 1 mm intervals for the first 5 mm rainfall and all volume of rainwater after 6 mm for all precipitation events with an automatic wet only precipitation collector. According to the analyses of precipitation including Kosa aerosols during Kosa periods, the reaction in the air between Kosa and acidic components during the long-range transport was discussed. 相似文献