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101.
The constitutive theory on the viscoelastoplasticity and damage of frozen soil is based on the continuous mechanics and thermodynamics. The basic principles of the theory, dissipation potential function and damage model are presented. The constitutive theory explains the mechanical properties of frozen soils under complicated stresses, especially under high confining pressures which make frozen soil harden and soften. The agreement between the calculated results by the constitutive theory and the experimental results of triaxial creep of frozen soil is seen to be very good. 相似文献
102.
Triassic alkaline intrusives in the Yanliao-Yinshan area: their chronology, Sr, Nd and Pb isotopic characteristics and their implication 总被引:14,自引:0,他引:14
Guohan Yan Baolei Mu Baoliang Xu Guoqi He Linkun Tan Hui Zhao Zhongfu He Renhu Zhang Guangsheng Qiao 《中国科学D辑(英文版)》1999,42(6):582-587
Dated isotopic ages for 15 alkaline intrusives in the Yanliao-Yinshan area, ranging from 268 to 190 Ma, ten of which are from
250 to 208 Ma, indicate that most of them were formed in the Triassic Epoch. All the ENd(t) ratios from - 17.19 to -3.21 averaging -7.09, the ESr(t) ratios fmm 11.7 to71.5 averaging 36.63, and the Isr(t) ratios from 0.705 0 to 0.709 3 averaging 0.706 8, show their characteristics of enrichment. On the ENd
(t) virus ESr(t) correlation diagram, the samples from these intmsives were plotted within the enriched mantle trend lines and just outside,
demonstrating their close connection to materials from the enriched mantle reservoir, taking into account the same Pb isotopic
composition as that of the mantle. 相似文献
103.
Living ostracod and hydrochemical samples were collected synchronously from more than 50 lakes and small water body in the eastern edge area of the Tibetan Plateau, Northern Tibetan, Southern Tibet and mid-Tibet. The comparison of the adult body length ofLimnocythere inopinata and hydrochemical parameters of their habitats shows that a quantitative relationship exists between the adult body length and salinity expressed as conductivity. An empirical formula to reconstruct paleosalinity is suggested first and applied to salinity reconstruction of CE-2 core from Cuoe Lake, Tibet. The method is verified by comparing its outcome with results of other environment reconstruction methods.
相似文献104.
XIONG Fahui YANG Jingsui Robinson T.PAUL XU Xiangzhen BA Dengzhu LI Yuan LIJinyang ZHANG Zhongming RONG He 《《地质学报》英文版》2015,89(Z2):99-100
<正>The first diamonds from ophiolite were found in peridotite of Luobusa ophiolite along Yarlung Zangbu suture zone in Tibet,China(IGCAGS,1981),and then more and more diamonds found in harzgurgite(Bai et al.,1993;Yang et al.,2007a;Robinson et al.,2014;Xu et al., 相似文献
105.
Stochastic modelling of soil moisture dynamics in a grassland of Qilian Mountain at point scale 总被引:6,自引:0,他引:6
Stochastic modeling of soil moisture dynamics is crucial to the quantitative understanding of plant responses to water stresses,hydrological control of nutrient cycling processes,water competition among plants,and some other ecological dynamics,and thus has become a hotspot in ecohydrology at present.In this paper,we based on the continuously monitored data of soil moisture during 2002―2005 and daily precipitation date of 1992―2006,and tried to make a probabilistic analysis of soil moisture dynamics at point scale in a grassland of Qilian Mountain by integrating the stochastic model improved by Laio and the Monte Carlo method.The results show that the inter-annual variations for the soil moisture patterns at different depths are very significant,and that the coefficient of variance(CV) of surface soil moisture(20 cm) is almost continually kept at about 0.23 whether in the rich or poor rainy years.Interestingly,it has been found that the maximal CV of soil moisture has not always appeared at the surface layer.Comparison of the analytically derived soil moisture probability density function(PDF) with the statistical distribution of the observed soil moisture data suggests that the stochastic model can reasonably describe and predict the soil moisture dynamics of the grassland in Qilian Mountain at point scale.By extracting the statistical information of the historical precipitation data in 1994―2006,and inputting them into the stochastic model,we analytically derived the long-term soil moisture PDF without considering the inter-annual climate fluctuations,and then numerically derived the one when considering the inter-annual fluctuation effects in combination with a Monte-Carlo procedure.It was found that,though the peak position of the probability density distribution significantly moved towards drought when considering the disturbance forces,and its width was narrowed,accordingly its peak value was increased,no significant bimodality was observed in the soil moisture dynamics under the given intensity of random fluctuation disturbance. 相似文献
106.
水系的分形维数及其含义 总被引:66,自引:6,他引:66
在分述水系分维数的几个计算方法基础上,对两上试区采用地图照相缩小后扫描以及图象处理的方法提取河流信息,以计盒方法计算水系的分维数,并据此提出划以域地貌侵蚀发育阶段的方法。 相似文献
107.
华南沿海地区太阳直接辐射、能见度及大气气溶胶变化特征分析 总被引:22,自引:5,他引:22
分析了中国华南地区福州、广州、海口、南宁等地1961~1990年太阳直接辐射总量、日照时数、总云量、大气能见度和地面水汽压等资料,并利用这些资料反演了该地区大气气溶胶的光学厚度值。结果表明:近30年来,华南地区太阳直接辐射总量和日照时数呈明显下降趋势。与60年代相比,80年代各站太阳直接辐射总量的年平均值均下降20%以上,其中广州下降29.2%;日照时数,广州减少了1.1 h,福州1 h,南宁0.9 h,海口0.5 h。分析发现,造成下降的原因不是由于云量或大气中水汽含量的变化,而是由于地面能见度的明显减小和大气气溶胶的增加。4站中,14时地面能见度均以夏季最好,最高值出现在7月;而地面能见度最差的季节海口、南宁两站在冬季,福州和广州两站在春季3、4月份。相比较而言,海口能见度最好,福州和南宁次之,广州最差。4站大气气溶胶光学厚度值的大小、年及季节变化与地面能见度有密切的关系,但两者不尽一致,因此,在研究气溶胶的辐射和气候效应时必须合理地考虑中高层大气气溶胶的分布。 相似文献
108.
东北振兴以来吉林省区域经济差异的时空演变研究 总被引:4,自引:6,他引:4
基于吉林省2003~2015年间地区生产总值和人均地区生产总值数据,以市域、县域两个尺度单元为研究对象,采用人口加权变异系数、基尼系数、泰尔指数等统计分析方法,对吉林省东北振兴战略实施以来的13 a内,区域经济差异的时空演变进行定量分析,并运用泰尔指数的分解方法,探讨了吉林省区域经济差异的空间格局。结果发现:① 吉林省区域经济总体差异、市域差异、县域差异均呈逐年下降趋势。② 通过差异贡献率显示:县域差异是区域总体差异变化的主导力量,长春市域的内部差异远高于其他市域,但有逐年减小的趋势,长吉两地的二元结构仍然突出,是全省区域经济差异产生的主要来源,主导着全省区域经济差异走向;③ 从2003~2015年来看,全省经济增长速度较快的地区主要还是集中在“三核一带”;④吉林省经济差异主要是由资源禀赋、产业结构、极化效应和政策导向等多种因素综合作用的结果。 相似文献
109.
以广州石屋新村为案例地,通过深入访谈、参与式观察以及收集文本材料等方式获取素材,运用扎根理论进行编码分析,探讨旅游发展背景下乡村空间正义主体博弈与协商的维度与过程。研究发现:① 乡村空间正义主体博弈与协商的内容主要包括分配正义、居住正义、边界正义和信仰正义4个维度,贯穿4个维度的核心和焦点是权力正义。② 4个维度彼此交织,相互影响,前2个维度呼应了马克思空间正义思想的部分观点,后2个维度是中国语境下的理论创新。③ 乡村转型发展过程中杂糅了政府、企业、村民各自的诉求,导致不同主体展演了多元复杂动态的空间正义博弈与协商过程。 相似文献
110.