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景宁县地处浙南山区。全县国土面积1949．98平方公里。其中山区面积占全县总面积的84．48％。山高坡陡,残坡积物多。地形、地貌、地质条件复杂。属亚热带季风气候区。降雨量充沛。是浙江省南部的一个暴雨中心。是全省地质灾害多发县之一。现已发现需防治的灾害隐患点122个。涉及全县23个乡镇。威胁7431人的生命财产安全。其中“A”类隐患点为4个,“B”类隐患点10个, 相似文献
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民国三十五年冬季笔者到宜昌,观察扬子江筑壩问题。调查地段由宜昌至石牌附近,长约二十五公里,沿江两岸宽二十余公里。此区地层自震旦纪灯影石灰岩起。寒武纪地层全部。奥陶纪地层一部份。上面覆以红色砾岩层。全区岩层走向大致 相似文献
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吉首历史悠久。春秋战国属楚。秦属黔中郡。汉属武陵郡。宋熙宁三年（1070）置镇溪砦（寨）,为军事要地。元属卢溪县。明洪武初年,朝廷设巡检司,发黄册,苗民反抗。明洪武三十年（1397）设镇溪千户所,隶辰州卫,形成＂里＂的编制,＂所里＂之名源于此。清康熙四十三年（1704）撤千户所为乾州厅,治乾州。民国二年（1913）置乾县,次年,因与陕西乾县重名,改为乾城县。由此可见,古代只有乾州,而无吉首之名。吉首在苗语中意为＂养育苗家的乙方水土＂。 相似文献
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《地质灾害与环境保护》2011,(3):88
本刊主管单位:四川省教育厅;主办单位:成都理工大学、地质灾害防治与地质环境保护国家重点实验室。学术性期刊,季刊。1990年创刊,国内外公开发行。大16开,每期112页,约22万字。欢迎订阅。 相似文献
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Inter-regional correlation of transgressions and regressions in the Cretaceous period 总被引：1，自引：0，他引：1
T. Matsumoto 《Cretaceous Research》1980,1(4):359-373
Well investigated platforms have been selected in each continent, and the history of Cretaceous transgressions and regressions there is concisely reviewed from the available evidence. The factual records have been summarized into a diagram and the timing of the events correlated between distant as well as adjoining areas.On a global scale, major transgressions were stepwise enlarged in space and time from the Neocomian, via Aptian-Albian, to the Late Cretaceous, and the post-Cretaceous regression was very remarkable. Minor cycles of transgression-regression were not always synchronous between different areas. Some of them were, however, nearly synchronous between the areas facing the same ocean.Tectono-eustasy may have been the main cause of the phenomena of transgression-regression, but certain kinds of other tectonic movements which affected even the so-called stable platforms were also responsible for the phenomena. The combined effects of various causes may have been unusual in the Cretaceous, since it was a period of global tectonic activity. The slowing down of this activity followed by readjustments may have been the cause of the global regression at the end of the Cretaceous. 相似文献
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城镇化是一个国家或地区经济发展的必经途径,同时也是衡量某地区经济发展水平的重要标志之一。城镇化进程不仅关系到区域人口、经济和环境的可持续发展,还关系到区域平衡与区域生产效率,以致关系到区域的综合竞争力。利用2001—2011年吐鲁番地区人口、经济、社会和生态方面的相关数据,剖析吐鲁番地区城镇化系统,选出并构建吐鲁番地区人口、经济、社会和生态4个城镇化系统的6个评价指标体系,对指标进行定量分析;计算城镇化4个系统以及城镇化发展水平的综合评价指数及其各系统的协调度,根据各子系统评价指数建立数学模型,分析吐鲁番地区城镇化驱动因子以及制约该地区城镇化进程的影响因素;并推算出吐鲁番地区城镇化的变化和发展趋势。 相似文献
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为研究吸力及压实度对非饱和压实填土压缩变形特性的影响,并建立脱湿（吸力增长）状态下的填方土体工后沉降变形修正计算应用模型,开展了控制吸力和压实度的一维非饱和土侧限压缩试验。结果表明：压缩曲线平缓段随压实度和吸力的提高而增长,表明土样的结构屈服强度同步得到提高;在比容v变化差值序列上,饱和土压缩土样最大、常规压缩土样次之、脱湿土样最小,并且吸力越大,比容v变化差值越小。经历脱湿（吸力增长）后的压实土压缩性降低,定义和建立了吸力压缩系数 及其经验模型,用以表征和度量吸力和压实度对压缩特性的影响规律及程度,发现 随竖向应力增加呈现指数型衰减。对模型参数与压实土相关参量间的关联性进行了分析探讨,同一压实度土样不同吸力所对应的参数 均值随压实水平提高而线性减小,参数λ总体上随吸力的增加而增大,但随压实度的提高吸力对于土体抗压性增强的贡献水平降低且参数 试验数值点靠拢线性趋近线,土样的压缩性随压实度和吸力大小变化而动态调整。基于分层总和法的基本原理初步构造建立了高填方非饱和填土压缩变形修正计算模型（MS）,其应用途径应建立在进一步对非饱和压实填土受荷状态下脱湿土-水特征关系的研究基础之上。 相似文献
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The Yenisei Range and the adjacent territories in the east are subdivided into (1) the Mid-Angara intracratonic depression; (2) the Yenisei pericratonic trough; and 3) a marginal oceanic block, the Isakovka-Predivinsk area. The lower part of the Riphean succession is subdivided into two principally different sedimentary complexes — the Lower Sukhoi Pit Subgroup and the Upper Sukhoi Pit Subgroup (the Pogoryui-Alad'in interval of the succession). The fundamental nature of the events that separate these two complexes and the characteristic, rhythmically bedded structure of the Upper Sukhoi Pit Subgroup allow the latter to be ranked a separate straton, the Bol'shoi Pit Group. Its lower boundary is associated with the Grenvillian events commencing with the emplacement of the Teya granite-gneiss domes and other intrusive complexes dated at 1100–1000 Ma. In the sedimentation record these events are manifested as a sudden change from the slate complex, for which we keep the name Sukhoi Pit Group, to the rhythmically bedded succession of the Bol'shoi Pit Group. The latter is interpreted as a product of uproofing of an elevated hinterland to the west. Insofar as the amplitude of this elevated area decreases progressively toward the Mid-Angara trough, the Bol'shoi Pit erosional unconformity and the associated interval of nondeposition are absent from the area. In the west of the Yenisei Range, in contrast, there is a major stratigraphic gap in the sequence, which is associated with the aforementioned events. The hypothesis on intensive events separating the deposition of the Bol'shoi Pit Group of the Kerpylian Horizon and the Tungusik Group of the Lakhandinian Horizon is not supported by the new data. The change from carbonate facies into siliciclastics in the west was misinterpreted as an erosional unconformity, with basal deposits corresponding to the lower boundary of the Tungusik Group. The occurrence of the Upper Tungusik deposits overlying much older rocks is a result of the pre-Bol'shoi Pit erosion and the gradual expansion of the Tungusik transgression. Thus, there are no grounds to argue for significant pre-Lakhandinian events in the region. Hence, the Kerpylian and Lakhandinian in the Yenisei Range, as well as in other parts of the Siberian Craton, constitute two parts of a larger supraregional straton, which corresponds to the lower half of the Upper Riphean and is designated here the Mayanian. The fundamentally different nature of the events associated with the next, Baikalian stage of the development allows its tripartite subdivision in the region. Deposition of the Lower Baikalian (the Oslyanka Group) was preceded by the crustal extension at the junction between the continental and oceanic blocks and, possibly, the formation of one of the Yenisei Range ophiolite complexes, followed by the emplacement of the Tatarka-Ayakhta batholiths at around 850 Ma. Fragments of both complexes are found as clasts in the basal conglomerates of the Middle Baikalian Chingasan Horizon. The specific character of the pre-Baikalian events determines their apparently poor expression in the sedimentation (weaker metamorphism of the Oslyanka deposits compared with the Tungusik Group). Even the activity leading to the formation of the Tatarka-Ayakhta granites cannot be regarded as a full-scale orogenic process. Collisional events separating the Lower and Middle Baikalian are manifested as the erosional unconformity at the base of the Chingasan Group and the emplacement of the Glushikha granites (760–730 Ma). The Middle Baikalian age of the Chingasan deposits is constrained by the data from paleontology, historical geology, and geochronology. Furthermore, the presence of glacial deposits renders this straton as a global stratigraphic marker. Further expansion of transgression in the Upper Baikalian is linked to another important event, but additional paleontological and geochronological information is needed to date the Upper Baikalian (Chapa Group) more accurately. The Baikalian events synchronously manifested themselves in all structural-facies zones of the Yenisei Range and are coeval to structural complexes from adjacent areas of the Siberian Craton. The tripartite Baikalian, therefore, has a potential for being included into the General Scale of the upper Upper Riphean. 相似文献
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在滨海地区,地下水水位受潮汐波动影响较大,使得传统的抽水试验、水位回复试验等方法确定含水层参数存在困难且花费较大。通过对广西北海市滨海含水层地下水位动态资料进行分析,发现其上升段和下降段是不对称的。基于海岸带承压含水层正弦潮汐波的传播理论,提出了确定含水层参数的分段法,并与振幅衰减法和滞后时间法进行对比,各种方法求出的储水系数与导水系数之比(S/T)很接近,说明分段法是有效的。对于北海市滨海含水层,上升段求出的S/T值比下降段要大,其成因机理还有待进一步分析。 相似文献
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B. D. Webby 《Australian Journal of Earth Sciences》2013,60(1-2):41-63
Much of South Australia, western New South Wales, and Tasmania was affected by the Late Cambrian‐Early Ordovician Delamerian Orogeny. Areas of the former shelf margin exhibit molasse‐type conglomerates overlying a major late Middle to Late Cambrian unconformity (Jukesian Movement in Tasmania or Mootwingee Movement in western N.S.W.). In continental platform areas to the north the effects of the orogeny were less intense with, in the Georgina Basin for instance, only dis‐conformable relationships, and the overlying deposits consisting of fine elastics and carbonates. Regression accompanied this first phase of tectonic upheaval and was followed by a period of ‘late Tremadoc’ transgression of the sea into several embayment areas of the continental platform. This short‐lived transgression was succeeded by ‘early Arenig’ regression which appears to be related to a second, less intense Delamerian orogenic phase. Expression of this phase ranges from unconformity in west Tasmania (Haulage and Lynchford Movements) to disconformity in the Georgina Basin (Kelly Creek Movement). A second, more extensive and long‐lived transgression of the sea from the ‘middle Arenig’ to about the end of the ‘Llanvirn’ resulted in the development of the epicontinental Larapintine Sea, permitting interchange of warmer and cooler waters from either ends of the seaway. Combined fossil, lithological and palaeomagnetic evidence suggests that, of the fragments of Gondwanaland, Australia alone straddled the Ordovician equator, with its present west coast approximately along the line of Lat. 30°S. Influxes of sand from the areas of mild‐high relief to the south appear to have been deflected in an anticlockwise direction along the open, ocean‐facing Gnalta Shelf of western N.S.W. towards the eastern end of the Larapintine Sea perhaps as a result of a major westward‐flowing equatorial current. The influxes progressively constricted and finally blocked off the eastern end of the seaway by the end of ‘Llanvirn’ time. The closure, and final regression of the sea from all continental platform areas, seems to have been accompanied by a phase of local uplift and erosion (Dullingari Movement of northeastern South Australia). In cratonic areas of central and northern Australia a period of Late Ordovician or Early Silurian uplift and erosion (Rodingan Movement) followed. Dullingari and Rodingan Movements may be correlated with phases of the Benambran Orogeny of the Tas‐man Geosyncline. Late Ordovician cratonic sedimentation was restricted to the shelf margin. On the Tasmanian Shelf carbonates accumulated during a long period of relative tectonic quiescence and gentle subsidence. First signs of onset of the Benambrian Orogeny are shown by the appearance of clastics in the topmost beds of the Tasmanian Ordovician sequence. 相似文献
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Geology and geochemistry of the Águas Claras and Pico Iron Mines, Quadrilátero Ferrífero, Minas Gerais, Brazil 总被引：1，自引：0，他引：1
Carlos Alberto Spier Sonia Maria Barros de Oliveira Carlos Alberto Rosière 《Mineralium Deposita》2003,38(6):751-774
The Águas Claras and Pico Mines are two world-class iron-ore mines hosted within the Lower- Proterozoic banded iron-formations (locally known as itabirites) of the Minas Supergroup located in the Quadrilátero Ferrífero district, Minas Gerais, Brazil. The Águas Claras orebody consists of a 2,500-m-long roughly tabular-shaped lens hosted within the dolomitic itabirite of the Cauê Formation. Dolomitic itabirite is the protore of the soft high-grade iron ore, which is the main ore type of the Águas Claras orebody, representing about 85% of the 284 Mt mined since 1973, with the remaining 15% comprising hard high-grade ore. Hematite is the main constituent of the iron ores. It occurs as martite, granular hematite and locally as specularite. Magnetite appears subordinately as relicts within martite and hematite crystals. Gangue minerals are very rare. These consist of dolomite, chlorite, talc, and apatite, and are especially common in contact with the protore. This virtual absence of gangue minerals is reflected in the chemistry of ores that are characterized by very high Fe contents (an average of 68.2% Fe).The Pico orebody is a continuous ~3,000-m-long body of a lenticular shape hosted within siliceous itabirite, which is the protore of the soft high- and low-grade ores at the Pico Mine. The soft high-grade ores, together with the low-grade ores, called iron-rich itabirite, are the main types of ore, and respectively represent approximately 51 and 29% of the reserves. The remaining 20% consists of hard high-grade ore. The iron oxide mineralogy is the same as that of the Águas Claras Mine, but in different proportions. Gangue minerals are very rare in the high-grade ores, but are slightly more common in the iron-rich itabirite. Quartz is the dominant gangue mineral, and is found with minor quantities of chlorite. The chemistry of the high-grade ores is characterized by high Fe contents (an average of 67.0%) and low P, Al2O3, and SiO2, which are concentrated in the fines. Iron-rich itabirites average 58.6% Fe and 13.5% SiO2.The genesis of the soft high-grade ores and iron-rich itabirites is related to supergene processes. Leaching of the gangue minerals by groundwater promoted the residual iron enrichment of the itabirites. This process was favored by the tropical climate and topographic situation. The original composition of the itabirites and the presence of structures controlling the circulation of the groundwater have influenced the degree of iron enrichment. The hard high-grade ores are of a hypogene origin. Their genesis is attributed to hydrothermal solutions that leached the gangue minerals and filled the spaces with hematite. This process remains a source of debate and is not yet fully understood.Editorial handling: S.G. Hagemann 相似文献
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One of the puzzling features of the southern end of the Rhine graben is the Dinkelberg-Tabular Jura block on the eastern shoulder of the graben. It is dissected by a large number of faults, the most notable ones forming a field of narrow little grabens and half-grabens whose bordering faults converge at the level of the Middle Triassic evaporites, which points to décollement at that horizon. The little grabens were traditionally considered to be of Oligocene age, coeval with the main taphrogenesis of the Rhine graben. Two hypotheses were offered for their formation, one ascribing them to extension on the extrados of large basement folds, the other to gravity sliding on paleoslopes. Recent field work uncovered overwhelming evidence for an Eocene age of the little grabens, the time of the initial phase of Rhine graben formation. At that time there were neither large basement folds nor paleoslopes of any significance, and therefore the two hypotheses offered until now do not work. However, the map-view pattern of the field of faults offers a somewhat unusual way out of the dilemma. This pattern is most prominently displayed in the Dinkelberg area north of the Rhine. There a lane of narrow décollement grabens with a mean NNE strike is confined within the NW- striking Dinkelberg graben, which is much wider and rooted in the basement. It is also very shallow, with a subsidence on the order of 100 m. The lane of décollement grabens forms a dextral en-échelon pattern with respect to the Dinkelberg graben, suggesting stretching of the post-evaporite sequence above a basement essentially extended by strike slip. This model, though not as clearly expressed, is also compatible with the data in the rest of the Dinkelberg-Tabular Jura block. It also fits surprisingly well a theoretical model by Withjack and Scheiner (1982) that predicts a dominance of strike-slip in the marginal area of a system consisting of extension superimposed on doming. 相似文献
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癌细胞与正常的人体细胞不同。根据体细胞突变理论（SMT）,癌细胞是基因突变的结果。该理论还采用达尔文主义的基本原理,假设癌细胞生长是自然选择下“适者生存”的结果。与此相反,我们采用Margulis的演化理论来解释癌症的起源,并提出癌细胞由遗传而来：癌基因组起源于寄生在原核生物宿主中的细菌;在大约20亿年前的“氧气革命”期间,癌基因组与原核生物基因组因内共生作用而融合;后来宿主演化成为真核生物（原生生物、真菌、植物和动物）,每种真核生物都具有其独特的基因组;经过同样的时间间隔,原寄生细菌基因组则演化成为真核生物内的癌干细胞基因组。当前SMT假设人类基因组的突变导致癌症,但该理论无法识别编码肿瘤生长的基因组序列,也无法解释：突变为何会造成癌细胞失控性生长及复制？癌症为何是一种代谢性疾病？癌症死亡率为何与亚硝酸盐污染有关？中国用不含亚硝酸盐的公共供水源的试验为何竟可以拯救许多癌症患者的生命？SMT没能充分回答许多“神秘”的癌症问题。相反,我们提出的生物演化理论可以回答这些相关事实,包括那些SMT不能充分解释的问题。我们的理论根据是：癌基因组图谱（TCGA）的科学家未能在正常的人类基因组序列中发现突变或未突变的癌基因组。是癌基因组编码了癌细胞的生长及复制和一种不同的代谢模式。我们的理论假设,癌症起源于“休眠中”的癌干细胞因为受亚硝酸盐的影响而被激活,其中一个癌基因组编码了厌氧或缺氧的代谢模式,为癌细胞的生长及复制提供能量和生物量,其他基因组则编码了癌细胞的失控性生长及复制和其他癌症特征。亚硝酸盐以10-9 级别的浓度干扰人体正常的代谢和复制等机能。事实说明,亚硝酸盐可被定义为一种毒药。识别慢性中毒的困难可以用孟加拉国公共供水造成的砷中毒作为例证。癌症应被视为由亚硝酸盐中毒引起的疾病来进行治疗是一个假说,它可以解释为什么当中国部分地区的正常公共供水改用标准化深井水（SDWW）时,癌症死亡率可以减半。这个假说需要另一个假设来解释亚硝酸盐中毒并不影响所有饮用公共供水的人,而只影响其中一部分人。我们必须假设癌症的产生是由于干细胞,其中包括一个癌干细胞,被召唤去以修复细胞的损伤。将这些打破常规的假说放在一起,很多专家认为我们的生物演化理论是天方夜谭而不予理会。实际上,这个假说已由中国过去的SDWW实验所证实。一些医院的试验也证实,若癌症晚期患者每天饮用不含亚硝酸盐的水,癌症可以被治愈。我们对癌症晚期不可治愈这一论断提出质疑,并假定癌症是慢性亚硝酸盐中毒所致。我们呼吁其他科学家进行实验和临床试验来验证这一假说,使至少一半的晚期癌症患者,当他们的饮用水供应源不含亚硝酸盐时,可以被治愈。与此同时,我们应该将过去半个世纪以来献身医学的科学家们的成果,整合为一个“新的体系”。 相似文献
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The expression of different ethnic identities in the landscape is a product of the creation, destruction and preservation
of the built environment. This may illustrate the changing processes over the evolution of a landscape. In the case of Braşov,
Romania, it is possible to see in the urban landscape a reflection of the changing nature of the relationship between the
ethnic German and Romanian populations, and the German and Romanian governments. This paper will demonstrate the persistence
of ethnic German culture in the built environment and social organisation of Braşov in spite of the exodus of the ethnic German
population.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献