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471.
本文采用HNO3-H2O2体系,应用AFS—2202a型双道原子荧光分光光度计,建立了氢化物发生—原子荧光测定黄芪中汞的测定方法.同时,研究了硼氢化钾浓度,光电管负高压,灯电流,原子化器高度,屏蔽气和载气流量等对测定结果的影响.在选定实验条件下,汞的检出限为0.027μg/L,桃叶(GBW08501)验证结果与推荐值一致,六次测定结果相对标准偏差为0.28%.  相似文献   
472.
通过对甘肃陇东黄土高原区的生态环境现状和成因的分析,指出人类的掠夺性行为加速了本区脆弱生态环境的恶变,并提出了陇东黄土高原区生态环境建设与可持续农业发展的对策。  相似文献   
473.
    
《科学通报(英文版)》1991,36(17):1471-1471
  相似文献   
474.
青海海北高寒草甸植被多样性研究   总被引:2,自引:0,他引:2  
本文对青藏高原高寒草甸和灌丛植被的分布、植物区系、生态特征进行了简要介绍,重点分析了青海海北地区高寒草甸植被类型、层片结构、生态型的多样性以及植物物种多样性、植物功能群多样性,旨在为高寒草甸生态系统的深入研究提供基础资料及科学依据.  相似文献   
475.
Guliya ice core records, high lake-level records in the Qinghai-Xizang Plateau and at its north side as well as vegetation succession records indicated that during the period of 30–40 kaBP, namely the later age of the megainterstadial of last glacial period, or the marine oxygen isotope stage 3, the climate of the Qinghai-Xizang Plateau was exceptionally warm and humid, the temperature was 2–4°C higher than today and the precipitation was 40% to over 100% higher than the current average, all these suggested the existence of an exceedingly strong summer monsoon event. It has been inferred that the occurrence of such an event was attributed, on the one hand, to the stronger summer low pressure over the Plateau, which strengthened the attraction to the summer monsoon; on the other hand, to the vigorous evaporation of the tropic ocean surface, which promoted the moisture-rich southwest monsoon to flow over the Qinghai-Xizang Plateau. The background responsible for the formation of the very strong summer monsoon was that the period of 30–40 kaBP was just in the strong insolation stage of the 20ka precessional cycle, when the Qinghai-Xizang Plateau received extraordinary strong solar radiation and thus enlarged the thermodynamical contrast between the Plateau and the midsouth part of the Indian Ocean.  相似文献   
476.
目的:通过比较初进高原(1周之内)的汉族与高原世居藏族的血常规18项指标及血压、心率、血氧饱和度,研究低氧对机体代谢功能的影响,尤其是低氧对机体血液学指标的影响。方法:采用指尖采血的方法,利用Sysmax的Poch100i型血液自动分析仪(日本产)进行血常规18项指标的检测;使用水银血压测量仪进行静息状态下右上肢肱动脉血压的测定;测定静息状态下的心率;使用NP-40型血氧饱和度测定仪(日本)检测血氧饱和度。采集的数据利用SPSS统计软件进行分析。结果:①进藏1周之内的汉族,其血红蛋白、红细胞压积、平均血红蛋白量、平均血红蛋白浓度、血小板、白细胞计数均小于世居高原的藏族(P〈0.05),而红细胞计数、平均红细胞体积与世居高原的藏族无差别(P〉0.05);②进藏1周之内的汉族的收缩压、舒张压、心率均高于世居高原的藏族(P〈0.05),而血氧饱和度却低于世居高原的藏族(P〈0.05);结论:进藏1周之内的汉族在红细胞系统指标(HGB、HCT、MCH、MCHC)及血压、心率、血氧饱和度等指标与世居高原的藏族青年存在明显差异。应进一步扩大样本量,以阐明汉族在高原习服过程中上述指标的变化程度和变化规律,为更好地了解高原习服的机制提供理论依据。  相似文献   
477.
蒙古族传统体育改革思路   总被引:2,自引:0,他引:2  
阐述了蒙古族传统体育的发展现状与改革思路,蒙古族传统体育要实现自身的生存与发展,必须主动适应体育全球化和市场经济的要求,走综合创新和产业化发展的道路,要确定优先发展领域,完善运作机制,加强对外交流,拓展市场空间,将民族传统体育纳入学校体育教学内容之中。  相似文献   
478.
  总被引:16,自引:0,他引:16  
Zhu  LiPing  Xie  ManPing  Wu  YanHong 《科学通报(英文版)》2010,55(13):1294-1303
By using remote sensing and GIS technologies, spatial analysis and statistic analysis, we calculated the water area and volume variations of the Nam Co Lake from 1971-2004, and discussed their influence factors from the viewpoints of climatic change and water balance. Data source in this study includes bathymetric data of the lake, aerial surveyed topographic maps of 1970, remote sensing images of 1991 and 2004 in the lake catchment, meteorological data from 17 stations within 1971-2004 in the adjacent area...  相似文献   
479.
  总被引:3,自引:0,他引:3  
Hou  Shugui  Qin  Dahe  Yao  Tandong  Zhang  Dongqi  Chen  Tuo 《科学通报(英文版)》2002,47(20):1746-1749
Three ice cores recovered from the Himalayas (i.e. the East Rongbuk Glacier and the Far East Rongbuk Glacier at Mt. Qomolangma (Everest), and the Dasuopu Glacier at Xixiabangma) show a sharp decline in the accumulation rates since the 1950s, which is consistent with the precipitation fluctuation over India and the low northern latitude zone (5°-35°N). Correspondingly, an increasing trend is observed for the ice core accumulations from the central and northern Qingh ai-Tibetan Plateau (i.e. the Xiao Dongkemadi Glacier in the central Tanggula Mountains, the Guliya Ice Cap in the western Kunlun Mountains, and the Dunde Ice Cap in the Qilian Mountains) since the 1950s, which is consistent with the precipi tation fluctuation over the middle-high northern latitude zone (35°-70°N). However, the variation magnitude of the high-elevation ice core accumulations is more significant than that of precipitation at the low-eleva- tion places, suggesti ng its extra sensitivity of high-elevation areas to climatic change. The inter-d ecadal abrupt change of the African-Asian summer monsoon in the1960s may attribute to the recent ice core accumulation change during the recent decades.  相似文献   
480.
  总被引:3,自引:0,他引:3  
The fluvial terrace sequence in eastern Qilian Mountains is a record of periodic uplift events of the Tibetan Plateau. Based on paleomagnetic dating, thermolumines-cence dating, radio carbon dating and loess-paleosol sequence on terraces, we preliminarily determine the ages of five major terraces of the Shagou River, northern side of the Qilian Mountains. The ages of five terraces were about 830, 418, 250,140 and 10 ka, respectively. Analysis on characteristics of terraces show that five major terraces were mainly tectonic genesis. Therefore, five major terraces recorded five strong rising events in the Qilian Mountains during the past 830 ka. The ages of those rising events are about the same as those terraces formation. Sub-terraces, constituting a main terrace, were perhaps mainly formed by climatic changes.  相似文献   
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