宇宙成因核素10Be:估算长江流域侵蚀速率的新方法

首次将宇宙成因核素10Be方法引入对长江流域地表侵蚀速率的研究.对长江流域东西子流域的对比发现,长江干流西部流域10Be含量普遍高于东部流域,这主要与长江上游高海拔导致的核素产生率高有关;西部流域主要支流10Be含量较低,反应了较高的侵蚀速率.通过金沙江、岷江-大渡河和沅江不同子流域的10Be含量与侵蚀速率关系模型,估算出岷江-大渡河流域平均侵蚀速率为300～500mm·ka-1,长江中下游地区的沅江-湘江流域侵蚀速率为30～50 mm·ka-1.与水文数据推导的侵蚀速率相比而言,二者在数量级上基本一致,反映了宇宙成因核素10Be法在估算侵蚀速率方面的有效性和可靠性,为研究长江流域侵蚀与沉积问题提供了一种有效的定量方法.     

宇宙成因核素10Be,26Al:原理及其在地表过程中的应用

地表岩石中宇宙成因核素10Be和26Al含量是侵蚀速率和辐射时间的函数,通过对岩石中10Be和26Al含量的测定能反映较长时间(103~107a)和较大空间尺度上的侵蚀作用大小和过程.根据10Be含量估算出长江中下游地区平均侵蚀速率为30~60m·Ma-1,攀枝花至三峡长江流域内地表平均侵蚀速率为200m·Ma-1.     

宇宙成因核素10Be,26Al:原理及其在地表过程中的应用

地表岩石中宇宙成因核素10Be和26Al含量是侵蚀速率和辐射时间的函数,通过对岩石中10Be和26Al含量的测定能反映较长时间(103～107a)和较大空间尺度上的侵蚀作用大小和过程.根据10Be含量估算出长江中下游地区平均侵蚀速率为30～60 m·Ma-1,攀枝花至三峡长江流域内地表平均侵蚀速率为200m·Ma-1.     

应用宇宙成因核素10Be和26Al估算剥蚀面的暴露时间及剥蚀速率和剥蚀厚度

宇宙成因核素10 Be和2 6Al的浓度记录着岩层剥蚀面的暴露时间和岩石剥蚀速率等信息。利用数学换算法分析影响10 Be和2 6Al浓度的因素 ,并利用10 Be和2 6Al的半衰期的近似倍数关系建立联立方程组 ,从理论上得到了年轻地质体中遭受快速埋藏的剥蚀面的暴露时间和剥蚀速率的估算公式。在此基础上 ,对整个剥蚀区不同位置剥蚀速率进行了分析。通过分析可以更准确地估算出整个剥蚀区不同位置的剥蚀厚度 ,从而可恢复剥蚀面的古地貌。     

应用宇宙成因核素^10Be和^26Al估算剥蚀面的暴露时间及剥蚀速率和剥蚀厚度

宇宙成因核素^10Be和^26Al的浓度记录着岩层剥蚀面的暴露时间和岩石剥蚀速率等信息。利用数学换算法分析影响^10Be和^26Al浓度的因素,并利用^10Be和^26Al的半衰期的近似倍数关系建立联立方程组,从理论上得到了年轻地质体中遭受快速埋藏的剥蚀面的暴露时间和剥蚀速率的估算公式。在此基础上,对整个剥蚀区不同位置剥蚀速率进行了分析。通过分析可以更准确地估算出整个剥蚀区不同位置的剥蚀厚度,从而可恢复剥蚀面的古地貌。     

广西南流江流域降雨侵蚀力时空变化特征

降雨是区域土壤侵蚀的主要动力因素之一,估算和分析降雨侵蚀力是区域水土流失治理与评价的基础工作。利用南流江流域内各气象站点1961—2006年的日雨量资料,基于日雨量模型估算降雨侵蚀力,并通过趋势分析、小波分析和Kriging空间插值法,定量分析广西沿海红壤区南流江流域降雨侵蚀力的时空变化特征与规律。结果显示,1961—2006年间,南流江流域年均降雨侵蚀力为13 935.5 MJ·mm·hm~(-2)·h~(-1)·a~(-1),年均降雨量为1 712.8mm,降雨侵蚀力变化周期约为14a。各年际和时间段间变化差异不明显,降雨侵蚀力年内集中分布在夏季,占比达57.0%,冬季最小,占比3.8%;在空间上,降雨侵蚀力与降雨量分布格局相似,呈现从西南沿海向东北内陆递减的趋势,行政区划上以钦南区和合浦县最大,北流市和玉州区最小。研究结果可为南流江流域土壤侵蚀风险和生态修复治理等工作提供一定的科学依据。     

长江流域年降水量的空间特征和演变规律分析

为获取长江流域年降水量的时空变化特征,对长江流域年降水量进行了空间分区和时间演变分析.根据长江流域146个气象站点1960~2005年的逐年降水量资料,采用经验正交函数和旋转经验正交函数对长江流域年降水量的空间变化特征进行分析,并计算了1960~2005年年降水量的线性演变规律,利用奇异谱分析方法来检测区域降水量发生突变的情况.结果表明,长江流域年降水量主要有3种空间分布型、8个降水变化敏感区域.8个敏感区域中,汉江流域、岷江-嘉陵江源区、乌江流域南部年降水量呈减少趋势,其中岷江-嘉陵江源区减少最为显著,年降水量每10年减少27.1 mm;洞庭湖-鄱阳湖地区、鄱阳湖流域南部、太湖流域、金沙江流域中部、云南地区年降水量呈增加趋势,其中金沙江流域中部年降水量显著增加,年降水量每10年增加17.7 mm.存在降水突变的地区有5个,下游的太湖流域发生最早,时间为1977年,上游云南地区最晚,为1998年.长江流域年降水量有比较明显的空间区域特征,各个区域年降水量的时间演变规律也不一致.     

基于WaTEM/SEDEM模型的双枫潭流域侵蚀产沙模拟

采用WaTEM/SEDEM模型,以湖南省3个流域为研究对象,利用莲花堰和石门坎水文站水沙数据对模型进行校正和验证,并将验证后的模型模拟双枫潭流域的侵蚀产沙,模拟结果表明:双枫潭流域年均产沙模数为631t/km2;受地形和土地利用的影响,流域侵蚀模数在0~10°坡度范围内总体呈现沉积,而在大于10°的坡面上侵蚀强度随坡度增加而增加.流域内旱地土壤侵蚀强度为3 345t/(km2·a);草地侵蚀速率为430t/(km2·a);林地和灌木林用地总体上表现为沉积,其沉积速率分别为110和83t/(km2·a).将以上模拟结果与其他相关研究比较,证实WaTEM/SEDEM模型在模拟流域侵蚀产沙方面有很好的应用前景,利用该模型可为流域水土保持措施实施提供科学依据.     

第2届全国水工抗震防灾学术交流会将在成都召开

第2届全国水工抗震防灾学术会议将于2009年5月12~14日在成都市举行.汶川特大地震影响波及全国,震中及周边地区震灾十分严重,人民生命财产遭受了巨大损失,基础设施受到严重破坏.西部地区是我国水能资源最丰富的地区,主要集中在岷江、大渡河、雅砻江、金沙江、澜沧江、怒江等流域     

大渡河流域土壤侵蚀强度时空变化格局分析

基于大渡河流域的地理国情(地势陡峻,林草地广布),改进了土壤可蚀性因子K、坡度坡长因子LS和植被盖度因子C的提取方法,构建了大渡河流域土壤流失方程,进而分析和探讨了2005—2015年大渡河流域土壤侵蚀时空变化分布格局及其驱动机制。研究结果表明:(1)大渡河流域总体上属于轻度侵蚀,其空间格局表现为小面积的高强度侵蚀,主要分布于中上游地区的高山峡谷地带以及下游的泸定县、九龙县、汉源县、峨边彝族自治县等地区。(2) 2005—2015年,大渡河流域土壤侵蚀变化状况呈现总体稳定,局部加剧的态势。(3)近十年国家退耕还林还草政策的实施有效地改善了流域水土流失状况,然而不合理的人类活动和频繁的地质灾害(特别是地震)极大地加剧了区域土壤侵蚀强度。研究成果可以为西南山区,特别是横断山区的土壤侵蚀量估算提供重要借鉴,对区域水土保持的防治具有重要参考意义。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that