排序方式: 共有54条查询结果,搜索用时 15 毫秒
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黄河源区蒸散发量时空变化趋势及突变分析 总被引:4,自引:1,他引:3
蒸散发量是流域水文过程的关键因子。由于缺乏区域面上实际蒸散发量的长期观测,很难得到长时间序列的蒸散发时空变化趋势。因此,本研究首先利用架设在黄河源若尔盖地区的涡动相关系统观测的2010年全年的蒸散发资料进行分析,对欧洲中心提供的ERA-interim和美国国家环境预报中心(NCEP)提供的地表变量再分析数据集进行了局地适用性评估,并依据再分析蒸散数据集,基于统计学方法分析了1979~2014年黄河源区蒸散发量的时空分布及变化特征。结果表明:(1)ERA-interim蒸散发再分析资料在黄河源区适用性较好,均方根误差为0.63,NCEP蒸散发再分析资料在4~7月、10~12月模拟值偏高,均方根误差为0.81。(2)进而利用ERA-interim蒸散发再分析资料,基于Mann Kendall方法及Sen斜率(Sen’s slope estimator)检验法,分析了黄河源区蒸散发量在1979~2014年期间的变化趋势。黄河源区蒸散发量总体上呈现北高南低的年变化趋势,北部兴海—共和—贵德地区增加最为迅速,年变化率在1.5~2.5 mm/a,西南部曲麻莱—治多—玉树地区减少最为明显,变化率为-1.0~-0.5 mm/a,东南部玛沁—玛曲—久治地区蒸散发量的变化在0.5~1.0 mm/a。(3)利用滑动t检验和SQMK(Sequential Mann Kendall)方法检测出发生突变的年份集中在20世纪80年代。 相似文献
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刘蓉 《国土资源导刊(湖南)》2009,6(8):43-44
昨日久未见面的几个朋友聚在一起"夜宴",从不碰股票的L君不住的感慨,如果我有钱,我就去买浏阳河边上的房子!理由是:政府刚出台了个超级规划,将由美国知名公司操刀的立体风光带建设,包括湘江风光带都不具备的功能分区,生活前景"一片光明". 相似文献
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新经济条件下我国生产性服务业的发展 总被引:7,自引:0,他引:7
探讨在新的经济条件下我国生产性服务业受到的影响,对生产性服务业做了较全面的认识,分析了新经济条件下的经济自由化对生产性服务业的影响,以及新经济条件下的网络经济对生产性服务业的影响,提出了我国生产性服务业的今后发展的几点思考。 相似文献
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江苏某抽水蓄能电站,上库主坝为混凝土面板堆石坝,由于上库防渗面板基础开挖量大,开挖料大多数为强风化粉砂质泥岩和强风化泥质粉砂岩,拟利用部分强风化中下部开挖料作为主坝填筑料,对于达到挖填平衡、保护环境、减少弃料及提高经济效益具有重要意义。为此对强风化岩石进行了岩石物理性质、抗压强度、压缩变形、矿物成份分析、化学分析等试验研究,同时进行了岩石干湿、变温多次循环疲劳物理力学特性试验,揭示了强风化岩石在干湿、变温循环条件下的变化规律,对于强风化岩石的可利用性及预测其长期稳定性提供了科学依据。 相似文献
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The Hengshan area in Shaanxi Province is located at the transitional junction of the Loess Plateau and the Mu Us sandy land in China. It is sensitive to environmental changes and has formed a unique paleoaeolian sand loess paleosol sequence. In this study, the L3 and S3 loess paleosol strata of the Liushumao section in Hengshan were selected for the analysis of the element content and related geochemical parameters in soil samples, to systematically explain the chemical weathering intensity and environmental evolution information recorded by the element geochemical index parameters during the L3 loess accumulation and S3 paleosol development in the Hengshan area. The results show that the major elements in the Liushumao section are mainly SiO2, Al2O3 and CaO. There are differences in the content of major elements in loess layers (L3-1, L3-2), paleosol layers (S3-1, S3-2), and aeolian sand layers (L3F, S3F). The contents of Al2O3 and Fe2O3 are the highest in the paleosol layer of the section, the content of CaO is the highest in the loess layer, and the content of Na2O is the highest in the aeolian sand layer. The CIA and Na/K values of the section samples reveal that the loess-paleosol layer are in the stage of primary chemical weathering, and the aeolian sand layer has not entered the stage of chemical weathering. The high values of CIA, Rb/Sr ratio, and magnetic susceptibility in the Liushumao section indicate the strengthening of weathering and pedogenesis, the relatively warm and humid climate in this period, the increasingly strong summer monsoon, and the fixed contraction of the Mu Us sandy land. The high values of the ratio of silicon and aluminium (Sa) and > 63 μm particle content indicate the occurrence of strong winter monsoon, which led to the activation and expansion of the sandy land under the effect of dry and cold climate. One extremely cold period, two cold periods, and a relatively warm period occurred in the L3 loess accumulation period, while two warm periods and one cold period occurred in the S3 paleosol development period. The change of element geochemical indicators in the Liushumao section revealed that the climate change in the Hengshan area was mainly affected by the change of strength of the East Asian winter and summer monsoon, which is generally consistent with other climate change records in North China. The study results provide more evidence for exploring the climate and environmental changes in the transitional area of the Loess Plateau and Mu Us sandy land in China. © 2023, Editorial office of PROGRESS IN GEOGRAPHY. All rights reserved. 相似文献
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目的:观察藿夏苓泽汤治疗痰湿中阻型内耳眩晕症的临床疗效。方法:将82 例内耳眩晕症患者随机分为2组,治疗组42 例采用中西医结合治疗,对照组40 例单用西医常规治疗,治疗3周后观察2组的综合疗效及眩晕症状的改善情况。结果:总有效率治疗组为90.48%(38/42),对照组为70.00%(28/40),2组比较,差异有统计学意义(P<0.05);治疗组眩晕症状的改善程度优于对照组,组间比较,差异有统计学意义(P<0.05);不良反应发生率治疗组为9.52%(4/42),对照组为37.50%(15/40),组间比较,差异有统计学意义(P<0.01)。结论:西医常规疗法联合藿夏苓泽汤治疗痰湿中阻型内耳眩晕症疗效显著,不良反应少,值得临床推广应用。 相似文献
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由于ENVISAT/AATSR资料不同角度热辐射亮度值之间存在较高的相关性从而导致较大误差的产生,本文尝试避开这种误差源,只选取天底观测数据对黄土高原陇东地区整层大气水汽含量及地表温度进行反演.与MODIS整层大气水汽含量产品对比验证表明,本文结果与MODIS产品有一定差异,但是可以直接用于大气透过率的估算.结合野外观测数据对地表温度反演结果的检验表明,最大绝对误差为4.0 ℃,平均相对误差为5.0%,因此,该算法在黄土高原陇东地区应用比较成功. 相似文献
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