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271.
中国土地利用时空特征分析 总被引:195,自引:5,他引:195
在遥感技术与GIS技术的支持下,对中国近5年来土地利用的时间动态特征和空间动态特征进行了定量分析。具体表现为通过数学建模,利用土地利用动态度模型、土地利用程度模型、垦殖指数模型等对土地利用时空特征进行了分析。研究结果表明:5年间中国土地利用类型发生变化比较大的区域主要分布在东部和北部地区,特别是东北部地区土地利用类型变化比较剧烈,而西部变化相对缓慢;土地利用各类型中面积增加的有耕地、水域、建设用地和未利用地,而林地、草地面积减少;耕地增加的区域位于东北部地区,特别是黑龙江省耕地面积增加最多;林草地以及未利用地的面积变化主要发生在新疆、内蒙和黑龙江等地区,其它地区变化幅度相对较小。 相似文献
272.
273.
临汾龙子祠泉岩溶水系统水文地质特征及开发利用前景 总被引:1,自引:1,他引:1
在讨论了龙子祠泉岩溶水系统岩叶下水水文地质特征的基础上,岩溶地下水对开发利用前景进行了初步探讨。 相似文献
274.
Li CHEN Qingquan LIU and Jiachun LI .. Division of Engineering Sciences Institute of Mechanics Chinese Academy of Sciences Beijing China E-mail: qqliu@mail.imech.ac.cn 《国际泥沙研究》2001,16(4)
1 mTRODUCT1ONThe Loess Plateau in the central and westem China with an area of 430,(X)0 lQn2 is well known for itsancient cultUre and serious soil and water loss. About 287,(X)0 km2 of area in this region has an annualerosion be greatC than 1(XX) tlkIn2. The eroded soil totally amounts to more than 2.2 X l0' tons, amongwhich about l.6X 10' tons, on average, is delivered into the Yellow kiver mdeng the river one of thehighest sediment-laden rivers in the word. The serious soil erosion … 相似文献
275.
凯里地区红粘土的工程特性与评价 总被引:3,自引:0,他引:3
凯里地区红粘土是一种较好的建筑物地基土,它除具有一般红粘土的通性外,其最大的特点是胀缩性小,塌陷概率低,如果对它做出客观的工程地质评价并加以利用将会产生重大的经济效益。 相似文献
276.
晚第三纪塔里木盆地及以南地区煤和盐类矿产沉积特征研究 总被引:1,自引:1,他引:1
论述了晚第三纪塔里木盆地至藏、滇一带古构造和古地理气候背景及地层沉积特征。重点讨论了古气候对煤和盐类矿产沉积作用的影响,提出了今后找矿工作的动步建议。 相似文献
277.
氢化物发生—原子荧光光谱法测定煤样中的硒 总被引:6,自引:2,他引:6
采用氢化物发生原子荧光光谱法测定了煤样中的总Se。煤样选用高压闷罐强酸消解的方法进行处理,所得消解液经6mol/L HCl将Se(Ⅵ)还原为Se(Ⅳ),然后进行测定。标准工作曲线的线性范围为0-400μg/L Se,检测限为0.4μg/L Se。用标准参考物质煤飞灰对方法进行了验证,所得总Se含量与标准值相符,对ω为10^-6级Se的4次测定,RSD≤4.5%。 相似文献
278.
The Velenje area (almost 200 km2 with over 31,000 inhabitants) is based on the Šalek Valley, which became a leading area of industrialisation and urbanisation
after the Second World War, with consequent pollution problems. Various industrial plants polluted the river Paka while more
serious hazards arose through the coal mine which is a still causing landscape subsidence and the thermal power station in
the neighbourhood of Šoštanj which is a major source of sulphur dioxide and nitrogen oxide pollution. In 1987 there was an
ecological protest which marked the beginning of a sustainable development strategy for the community. During the past decade
programmes have dealt with the degradation of air, soil and water to achieve cleaner air, a transformation in landuse and
enhancement the river's formerly weak self-purifying capabilities. This article examines the changes in the valley since the
attention of the authorities was drawn to the deterioration of living conditions. Despite the pressures of transition which
have seen unemployment rising to over ten percent, significant environmental improvements have been made and the area stands
as a model for the rest of the country.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
279.
Generation of Deccan Trap magmas 总被引:1,自引:0,他引:1
Gautam Sen 《Journal of Earth System Science》2001,110(4):409-431
Deccan Trap magmas may have erupted through multiple centers, the most prominent of which may have been a shield volcano-like
structure in the Western Ghats area. The lavas are predominantly tholeiitic; alkalic mafic lavas and carbonatites are rare.
Radioisotope dating, magnetic chronology, and age constraints from paleontology indicate that although the eruption started
some 68 Ma, the bulk of lavas erupted at around 65–66 Ma. Paleomagnetic constraints indicate an uncertainty of ± 500,000 years
for peak volcanic activity at 65 m.y. in the type section of the Western Ghats. Maximum magma residence times were calculated
in this study based on growth rates of “giant plagioclase” crystals in lavas that marked the end phase of volcanic activity
of different magma chambers. These calculations suggest that the > 1.7 km thick Western Ghats section might have erupted within
a much shorter time interval of ∼ 55,000 years, implying phenomenal eruption rates that are orders of magnitude larger than
any present-day eruption rate from any tectonic environment. Other significant observations/conclusions are as follows: (1)
Deccan lavas can be grouped into stratigraphic subdivisions based on their geochemistry; (2) While some formations are relatively
uncontaminated others are strongly contaminated by the continental crust; (3) Deccan magmas were produced by 15–30% melting
of a Fe-rich lherzolitic source at ∼ 3–2 GPa; (4) Parent magmas of the relatively uncontaminated Ambenali formation had a
primitive composition with 16%MgO, 47%SiO2; (5) Deccan magmas were generated much deeper and by significantly more melting than other continental flood basalt provinces;
(6) The erupted Deccan tholeiitic lavas underwent fractionation and magma mixing at ∼ 0.2 GPa. The composition and origin
of the crust and crust/mantle boundary beneath the Deccan are discussed with respect to the influence of Deccan magmatic episode. 相似文献
280.
丘陵山区低空急流特性分析 总被引:1,自引:0,他引:1
利用丘陵区边界层实测资料,分析了该地区8-9月份低空急流的特征及其演变规律;并从测站所处的地理环境,山凰 地形的力差异以及适中的风平流作用等,探讨了测站上空逆温的形成及其对低空急流的形成和维持作用,根据地形热力差所导致的气压斜压性,研究了低空急流的生消可能机制。 相似文献