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Clay mineral distribution characteristics of surface sediments in the South Mid-Atlantic Ridge
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作者 Qiannan HU Chuanshun LI +4 位作者 Baoju YANG Xisheng FANG Huahua LÜ Xuefa SHI Jihua LIU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2023年第3期897-908,共12页
Clay minerals are usually considered as important indicators to identify sources in both terrigenous and marine sediments.In particular,clay minerals in metalliferous sediments(MS)have long been studied in global ocea... Clay minerals are usually considered as important indicators to identify sources in both terrigenous and marine sediments.In particular,clay minerals in metalliferous sediments(MS)have long been studied in global oceans except in South Mid-Atlantic Ridge(SMAR)due to limited explorations.Thus,32 MS and 34 non-MS(NMS)samples were analyzed to clarify the distribution characteristics and mineral compositions of clay minerals.All the sediments were collected along the SMAR between 12°S and 27°S.After removal of organic matter and carbonate,clay fractions(<2μm)were investigated by Xray diffraction(XRD)analysis.Results show that clay mineral assemblages of surface MS consist dominantly of smectite,less abundant illite,chlorite,and kaolinite in average weight percentage of 30%,21%,18%,and 16%,respectively.On the other hand,clay mineral assemblages in the NMS consist mainly of illite,less abundant kaolinite,chlorite,and very scarce smectite in average weight percentage of 47%,29%,24%,and 0.2%,respectively.The clay fractions in MS are mainly composed of amorphous or poorly crystallized Fe/Mn oxyhydroxides,clay mineral,quartz,and plagioclase.However,the counterparts in the NMS are mainly composed of well-crystallized clay minerals,quartz,and plagioclase without the presence of Fe/Mn oxyhydroxides.It is suggested that most of the illite,kaolinite,and chlorite in both MS and NMS are likely aeolian dust in origin from South Africa continent.In addition,the abundance of kaolinite dominates the clay mineral assemblage at low latitudes,where the intensive chemical weathering of continental source rocks facilitating the formation of kaolinite.In terms of smectite,it is indicated of authigenic origin in consideration of only smectite is available in several MS and the absence in NMS.Moreover,the MS samples with only smectite available are always accompanied by goethite.Therefore,it is assumed that most of smectite occurred in studied area is the results of interaction between hydrothermal Fe-oxyhydroxide,silica,and seawater. 展开更多
关键词 metalliferous sediment south Mid-Atlantic Ridge(SMAR) clay mineral SMECTITE
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THE PRELIMINARY STUDY ON LANDSCAPE CULTURE ORIENTATION AND EXPLOITATION OF THE SOUTH DONGTING LAKE WETLAND 被引量:4
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作者 HEPing WANGBao-zhong 《Chinese Geographical Science》 SCIE CSCD 2002年第3期254-261,共8页
Dongting Lake is internationally a n important wetland.We studied and s ummarized the conception,func-tion,classification and current situation of the wetland-landscape cu lture in this region.The results showed that ... Dongting Lake is internationally a n important wetland.We studied and s ummarized the conception,func-tion,classification and current situation of the wetland-landscape cu lture in this region.The results showed that the cul-ture of Dongting Lake wetland was ric h in diversity,which are the Rice Cul tivation Culture,high-balustrade dwelling,Nuo Culture,Ship Culture,Dragon Bo at Culture,Chu Culture,Ancient Arc hitecture Landscape,Wetland Foodstuff and Cuisine Culture,Civil Art,Historic Heritage and Cultural Relics,Revolutionary Sites and Ruins,and Production and Living Culture,etc.We also evaluated the eco-tourism value of wetland l andscape culture,and analyzed its f eatures and orientation.The results revealed t hat the south Dongting Lake wetland p lays a key role on the Changjiang(Yangtze)River reaches civilization and Chinese civilization,even has great influence on the global civilization.We summ arized that the soul of the south Dongting Lake Cultu re was Wetland Culture,Water Cultur e,Rice Cultivation and Chu Culture.The thoughts,principles and approaches of sustainable exploitation and ut ilization of the wetland landscape c ulture were formulat-ed and suggested. 展开更多
关键词 south dongting lake wetland landscape landscape culture ECO-TOURISM wetland culture
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On Characteristics and Cultures of the Hakka's Enclosed Houses in South Jiangxi Province 被引量:1
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作者 XIONG Jianxin LI Wenqin 《Journal of Landscape Research》 2012年第12期43-46,共4页
General situation and distribution of round houses of the Hakka in south Jiangxi were introduced, such architectural styles as enclosed house with a square yard (kouzi wei, in the shape of 口), enclosed house with a y... General situation and distribution of round houses of the Hakka in south Jiangxi were introduced, such architectural styles as enclosed house with a square yard (kouzi wei, in the shape of 口), enclosed house with a yard of three transverse and one longitudinal constructions (guozi wei, in the shape of 国), and enclosed house with a round house in its yard (tao wei) were taken to analyze features of the Hakka's enclosed houses. It was highlighted that the Hakka's enclosed houses in south Jiangxi has diversified architectural styles and outstanding defensive and living functions. Construction art and religious culture shown by the enclosed houses were interpreted, and the branch of Han people with unique dialects, cultures, folk customs and emotional attitudes was proposed as a miniature of the culture in south Jiangxi. Moreover, it was stressed that more attention of the public and more efforts for the protection should be given to the Hakka's cultures in south Jiangxi, carriers of the locals' history over the past thousands of years. 展开更多
关键词 south Jiangxi Enclosed house Architectural CHARACTERISTICS the Hakka’s cultureS
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Effect of South Korean Pop Culture on the Potential Tourists from Chinese Mainland 被引量:1
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作者 XIONG Yuan-bin LI Sheng 《Chinese Business Review》 2007年第2期20-25,32,共7页
Following along with South Korean Pop culture sweeping across Chinese Mainland, Chinese market of South Korea tour is developing rapidly. An analysis demonstrates that the movie and television industry of South Korea ... Following along with South Korean Pop culture sweeping across Chinese Mainland, Chinese market of South Korea tour is developing rapidly. An analysis demonstrates that the movie and television industry of South Korea is one of the most essential factors to attract the potential tourist from China. South Korean Pop culture is directly affecting rather the image of South Korean as a tourist destination than tourists' purchasing. And the paper suggests a set of "4S" strategy for South Korean to combine the elements of South Korean movies with those of tourism, so as to create an industrial development pattern characterized as "movies + tourism". 展开更多
关键词 south Korean Pop culture TOURISM EFFECT
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Study on the Inheritance Value of the Red Culture in South Jiangxi from the Perspective of Revitalizing Soviet Area
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作者 Qun LIN 《International Journal of Technology Management》 2013年第6期17-19,共3页
In this paper, through an analysis on the contents and present development of the red culture in South Jiangxi, the strategy of developing red culture tourism is proposed for promoting the economic development and enh... In this paper, through an analysis on the contents and present development of the red culture in South Jiangxi, the strategy of developing red culture tourism is proposed for promoting the economic development and enhancing the protection of the red cultural inheritance in the Soviet area. 展开更多
关键词 the Revitalization of Soviet Area Red culture the culture of south Jiangxi
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Initiation and evolution of the South China Sea: an overview 被引量:27
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作者 Weidong Sun 《Acta Geochimica》 EI CAS CSCD 2016年第3期215-225,共11页
Different models have been proposed for the formation and tectonic evolution of the South China Sea (SCS), including extrusion of the Indochina Peninsula, backarc extension, two-stage opening, proto-SCS dragging, ex... Different models have been proposed for the formation and tectonic evolution of the South China Sea (SCS), including extrusion of the Indochina Peninsula, backarc extension, two-stage opening, proto-SCS dragging, extension induced by a mantle plume, and integrated models that combine diverse factors. Among these, the extrusion model has gained the most attention. Based on simplified physical experiments, this model proposes that collision between the Indian and Eurasian Plates resulted in extrusion of the Indochina Peninsula, which in turn led to opening of the SCS. The extrusion of the Indochina Peninsula, however, should have led to preferential open- ing in the west side of the SCS, which is contrary to observations. Extensional models propose that the SCS was a backarc basin, rifted off the South China Block. Most of the backarc extension models, however, are not compatible with observations in terms of either age or subduction direction. The two-stage extension model is based on extensional basins surrounding the SCS. Recent dating results indeed show two-stage opening in the SCS, but the Southwest Subbasin of the SCS is much younger, which contradicts the two-stage extension model. Here we pro- pose a refined backarc extension model. There was a wide Neotethys Ocean between the Australian and Eurasian Plates before the Indian-Eurasian collision. The ocean floorstarted to subduct northward at ~ 125 Ma, causing backarc extension along the southem margin of the Eurasian Plate and the formation of the proto-SCS. The Neotethys sub- duction regime changed due to ridge subduction in the Late Cretaceous, resulting in fold-belts, uplifting, erosion, and widespread unconformities. It may also have led to the subduction of the proto-SCS. Flat subduction of the ridge may have reached further north and resulted in another backarc extension that formed the SCS. The rollback of the fiat subducting slab might have occurred ~ 90 Ma ago; the second backarc extension may have initiated between 50 and 45 Ma. The opening of the Southwest Subbasin is roughly simultaneous with a ridge jump in the East Sub- basin, which implies major tectonic changes in the sur- rounding regions, likely related to major changes in the extrusion of the Indochina Peninsula. 展开更多
关键词 south China Sea NEOTETHYS Platesubduction Ridge subduction Indochina Peninsulaextrusion Backarc extension Multiple plate interactionsProto south China Sea
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TEM investigations of South Atlantic Ridge 13.2°S hydrothermal area 被引量:3
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作者 TAO Chunhui XIONG Wei +2 位作者 XI Zhenzhu DENG Xianming XU Yixian 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2013年第12期68-74,共7页
According to the exploration contract about polymetallic sulfides in the SWIR (Southwest Indian Ridge) signed by China with the International Seabed Authority, to delineate sulfide minerals and estimate resource qua... According to the exploration contract about polymetallic sulfides in the SWIR (Southwest Indian Ridge) signed by China with the International Seabed Authority, to delineate sulfide minerals and estimate resource quantity are urgent tasks. We independently developed our first coincident loop Transient Electromagnetic Method (TEM) device in 2010, and gained the TEM data for seafloor sulfide at South Atlantic Ridge 13.2°S in June 2011. In contrast with the widely applied CSEM (Marine controlled-source electromagnetic) method, whose goal is to explore hydrocarbons (oil/gas) of higher resistivity than seawater from 102 to 103 m below the sea floor, the TEM is for low resistivity minerals, and the target depth is from 0 to 100 m below the sea floor. Based on the development of complex sulfide geoelectrial models, this paper analyzed the TEM data obtained, proposing a new method for seafloor sulfide detection. We present the preliminary trial results, in the form of apparent resistivity sections for both half-space and full-space conditions. The results cor- respond well with the observations of the actual hydrothermal vent area, and the detection depth reached 50-100m below the bed, which verified the capability of the equipment. 展开更多
关键词 transient electromagnetic method mid-ocean ridge hydrothermal activity seafloor polymetallicsulfides south Atlantic Ridge
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Abundance and Distribution of Fatty Acids in Sediments of the South Mid-Atlantic Ridge 被引量:4
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作者 HUANG Xin ZENG Zhigang +7 位作者 CHEN Shuai YIN Xuebo WANG Xiaoyuan MA Yao YANG Baoju RONG Kunbo SHU Yunchao JIANG Tao 《Journal of Ocean University of China》 SCIE CAS 2015年第2期277-283,共7页
Sediment samples obtained from the South Mid-Atlantic Ridge were studies by gas chromatography-mass spectrometer (GC-MS) for the abundance and distributions of total fatty acids (TFAs). Approximately 34 fatty acid... Sediment samples obtained from the South Mid-Atlantic Ridge were studies by gas chromatography-mass spectrometer (GC-MS) for the abundance and distributions of total fatty acids (TFAs). Approximately 34 fatty acids were identified, with the chain-lengths ranging from C12 to C30. The total concentrations of TFAs (∑TFA) ranged from 7.15 to 30.09 μgg-l dry sediment, and ∑TFA was weakly correlated with bitumen content (R2=0.69). The ∑TFA of samples around hydrothermal areas were significantly higher than that of samples away from hydrothermal areas, indicating intense primary production and large biomass in the hydro- thermal areas, and suggesting a close relationship between hydrothermal activity and ∑TFA of samples. The characteristics of the TFA composition in the present study are rich in monounsaturated fatty acids and lacking in polyunsaturated fatty acids, and the ra- tios between the concentrations of monounsaturated fatty acids and ∑TFAs in samples close to the hydrothermal areas, are about 0.8, but for samples far from the hydrothermal areas, they are only about 0.5. Several fatty acids (e.g., a/iC15:0 and C16:1co7), which are signature biomarkers for sulfur-metabolizing bacteria, show the same distribution trend as ∑TFA of samples, further highlighting the close relationship between fatty acid content and hydrothermal activity and/or hydrothermal communities. The metabolic activities of hydrothermal communities, especially those of microorganisms, are likely the main source of fatty acids in samples. 展开更多
关键词 south Mid-Atlantic Ridge SEDIMENT fatty acids hydrothermal activity MICROORGANISM
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Component characteristics of polycyclic aromatic compounds in sediments of the South Mid-Atlantic Ridge 被引量:2
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作者 HUANG Xin ZENG Zhigang +7 位作者 CHEN Shuai YIN Xuebo WANG Xiaoyuan MA Yao YANG Baoju RONG Kunbo SHU Yunchao JIANG Tao 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2014年第11期150-154,共5页
10 samples of sediments obtained from the South Mid-Atlantic Ridge were measured for the abundances and distributions of polycyclic aromatic compounds(PAHs). The total concentrations of PAHs(∑PAHs) ranged from 2.... 10 samples of sediments obtained from the South Mid-Atlantic Ridge were measured for the abundances and distributions of polycyclic aromatic compounds(PAHs). The total concentrations of PAHs(∑PAHs) ranged from 2.768 to 9.826 μg/g dry sediment. The ∑PAHs was higher in sample 22V-TVG10 and sample 26V-TVG05 which were close to hydrothermal fields, with the lowest value in sample 22V-TVG14 which was farthest from hydrothermal fields, suggesting a probable hydrothermal origin of ∑PAHs of samples. Approximately nine kinds of PAHs were identified, and low molecular mass tricyclic and tetracyclic aromatic compounds were predominant in the samples. The concentrations of fluoranthene which were typical as hydrothermal alteration compounds were the highest among PAHs with dry weight between 0.913–3.157 μg/g. The phenanthrene homologue was most abundant in the samples, and the ratios between parent phenanthrene and methylphenanthrene which probably reflected the degree of hydrothermal alteration ranged from 0.097 to 1.602. The sample 22V-TVG10 possessing a maximum ratio value showed the intense influence of the hydrothermal alteration on this sample, which might further imply that PAHs in sediments were mainly derived from the hydrothermal alteration. 展开更多
关键词 south Mid-Atlantic Ridge SEDIMENT polycyclic aromatic compounds hydrothermal activity
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Mathematical model of wave transformation over radial sand ridge field on continental shelf of South Yellow Sea 被引量:2
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作者 Yao-zhong YANG Wei-bing FENG 《Water Science and Engineering》 EI CAS 2010年第1期36-46,共11页
According to a deformed mild-slope equation derived by Guang-wen Hong and an enhanced numerical method, a wave refraction-diffraction nonlinear mathematical model that takes tidal level change and the high-order bathy... According to a deformed mild-slope equation derived by Guang-wen Hong and an enhanced numerical method, a wave refraction-diffraction nonlinear mathematical model that takes tidal level change and the high-order bathymetry factor into account has been developed. The deformed mild-slope equation is used to eliminate the restriction of wave length on calculation steps. Using the hard disk to record data during the calculation process, the enhanced numerical method can save computer memory space to a certain extent, so that a large-scale sea area can be calculated with high-resolution grids. This model was applied to wave field integral calculation over a radial sand ridge field in the South Yellow Sea. The results demonstrate some features of the wave field: (1) the wave-height contour lines are arc-shaped near the shore; (2) waves break many times when they propagate toward the shore; (3) wave field characteristics on the northern and southern sides of Huangshayang are different; and (4) the characteristics of wave distribution match the terrain features. The application of this model in the region of the radial sand ridge field suggests that it is a feasible way to analyze wave refraction-diffraction effects under natural sea conditions. 展开更多
关键词 wave transformation mathematical model radial sand ridge field south Yellow Sea
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The distribution and composition of hydrocarbons in sediments of the South Mid-Atlantic Ridge 被引量:1
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作者 HUANG Xin CHEN Shuai +3 位作者 WANG Xiaoyuan ZHANG Shuwen CHEN Fajin PU Xiaoqiang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2018年第1期89-96,共8页
Sediment samples obtained from the South Mid-Atlantic Ridge are analyzed by a gas chromatography-mass spectrometer(GC-MS) for the abundances and distributions of hydrocarbons. The hydrocarbons in the samples exhibit... Sediment samples obtained from the South Mid-Atlantic Ridge are analyzed by a gas chromatography-mass spectrometer(GC-MS) for the abundances and distributions of hydrocarbons. The hydrocarbons in the samples exhibit a bimodal distribution of n-alkanes and are rich in 3-methylalkanes, 8-methylalkanes and 2, 4,(n-1)-trimethylalkanes, which may be the result of metabolic activity of benthic microorganism. Terpanes, hopanes and steranes are all enriched in the samples, which also support the microbial origin of hydrocarbons in samples.Bitumen and hydrocarbons in the samples show a trend that the contents are the highest in the Samples 22V-TVG10 and 26V-TVG05 collected near hydrothermal areas, and the lowest in samples 22IV-TVG01, 22V-TVG11,and 22V-TVG14 collected far from the hydrothermal areas, which suggest the possible influence on the samples by hydrothermal activity. 展开更多
关键词 hydrocarbons south Mid-Atlantic Ridge SEDIMENT hydrothermal activity
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Ecological Benefits of Compound Ridge Culture in Hillside Orchard in the Three Gorge Reservoir Area 被引量:1
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作者 LIAO Xiaoyong CHEN Zhijian +2 位作者 WANG Haiming LUO Chengde LI Tao 《Wuhan University Journal of Natural Sciences》 CAS 2008年第3期357-362,共6页
Based on contour tillage of wide ridge and furrow covering and agro-forestry, this paper sets up a compound ridge culture mode in hillside orchards and introduces a long-term observation to the mode's effects on ecol... Based on contour tillage of wide ridge and furrow covering and agro-forestry, this paper sets up a compound ridge culture mode in hillside orchards and introduces a long-term observation to the mode's effects on ecological benefits of water and soil conservation. A five-year study shows that compound ridge culture in hillside orchards is effective in water and soil conservation, especially in reducing soil erosion. Compared with the traditional management modes of orchards, compound ridge culture has reduced runoff amount by 41.96%-57.96%, soil erosion amount by 55.47%-67.75%. Compound ridge culture also brings an obvious reduction of soil nutrient loss and of non-point source pollution, which is of great importance for keeping and increasing the productivity of hillside orchards in the Three Gorge Reservoir Area. 展开更多
关键词 hillside orchards compound ridge culture ecological benefits: the Three Gorge Reservoir Area
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An Anomalous Seamount on the Southwestern Mid-Ridge of the South China Sea 被引量:5
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作者 WANG Yanlin WANG Jun +1 位作者 YAN Pin QIU Yan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第6期2340-2341,共2页
Objective The development of continental rifting and seafloor spreading can be predominated by magmatic upwelling (magma-rich) or tectonic stretching (magma-poor). Located in the terminal portion of propagating s... Objective The development of continental rifting and seafloor spreading can be predominated by magmatic upwelling (magma-rich) or tectonic stretching (magma-poor). Located in the terminal portion of propagating seafloor spreading of the South China Sea (SCS), the southwestern mid-ridge of the southwest sub-basin (SWSB) of the SCS was found with much thin crust and numerous faulted blocks coupling with magma-poor continental margins along its flanks. Therefore, the southwestern part of the SWSB is most likely to be a tectonic-dominated basin. To justify the hypothesis with further evidence, we investigated the nature of seamounts on the southwestern mid-ridge of the SWSB which may inherit seafloor spreading. 展开更多
关键词 southwestern Mid-Ridge the south China Sea
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Effects of Different Ridge Culture Ways on Stem Diameter,Plant Height,the Number of Leaves and Yield of Phaseolus vulgaris L. under Dry Farming Conditions 被引量:1
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作者 NIE Hong-mei1,XING Guo-ming1,ZHENG Shao-wen1,WEN Bian-ying21. College of Horticulture,Shanxi Agricultural University,Taigu 030801 2. Vegetables Office in Yangqu County,Shanxi Province,Yangqu 030100 《Agricultural Science & Technology》 CAS 2010年第5期59-61,共3页
The variety "Aifeng" was used as experimental material,and the stem diameter,plant height,the number of leaves and yield of P. vulgaris under three ways of ridge culture (bedding,high ridge and M ridge) were... The variety "Aifeng" was used as experimental material,and the stem diameter,plant height,the number of leaves and yield of P. vulgaris under three ways of ridge culture (bedding,high ridge and M ridge) were observed and detected to study the effects of different ridge cultures on the growth and yield. The results showed that the stem diameter,plant height,the number of leaves and yield under M ridge culture were higher than that of bedding and high ridge. 展开更多
关键词 Phaseolus vulgaris L. Dry farming Ridge culture
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Institutionalized Power and Pederasty in the Ancient and Medieval South Asia -A Study of Literary Evidences of Love, Lust, and Violence Against Men
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作者 Sanyat Sattar 《Journal of Literature and Art Studies》 2018年第8期1214-1225,共12页
Even if the act of pederasty is considered as a heinous crime, if we look into the ancient South Asian history, we will find evidences where pederasty has been widely a common practice. The folk-tales, literature, mus... Even if the act of pederasty is considered as a heinous crime, if we look into the ancient South Asian history, we will find evidences where pederasty has been widely a common practice. The folk-tales, literature, music, and other cultural evidences of ancient South Asia provide us numerous references of institutionalized pederasty. This research will investigate on the causes and effects of pederasty of ancient South Asia and will probe into the matter how this necessitated the minors to lem-n about sexuality 展开更多
关键词 institutionalized pederasty south Asia POWER gender dominance culture
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Poverty Reduction, Cultural Narrative, and the Realization of Development Rights in South-South Cooperation
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作者 卜卫 HU Liang 《The Journal of Human Rights》 2018年第1期29-35,共7页
The development of any country or society requires a cultural context. A cultural narrative influence the process of development by shaping people’s views and actions, and thus policy. This paper first discusses the ... The development of any country or society requires a cultural context. A cultural narrative influence the process of development by shaping people’s views and actions, and thus policy. This paper first discusses the importance of cultural narratives, and then analyzes the different cultural narratives on poverty reduction, development, right to development, and South-South Cooperation. It illustrates how cultural narratives significantly influence social justice development and reforms. 展开更多
关键词 cultural narrative poverty reduction south-south Cooperation development rights
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Advancing Arts One village’s oil paintings lead the development of south China’s cultural industries
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作者 Zheng Yang 《ChinAfrica》 2013年第8期52-53,共2页
The Dafen art museum, the largest such museum in Shenzhen, was built int he village in 2007 to he a platform for art exhibitions and exchange,
关键词 Advancing Arts One village’s oil paintings lead the development of south China’s cultural industries
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Application of Eastern River Culture on Squares of Yuncheng City
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作者 程朝霞 《Journal of Landscape Research》 2009年第11期23-26,共4页
Taking South-wind Square in Yuncheng City for an example,the application of Eastern River Culture as a kind of regional culture in the construction of urban squares were analyzed in this study,to provide references fo... Taking South-wind Square in Yuncheng City for an example,the application of Eastern River Culture as a kind of regional culture in the construction of urban squares were analyzed in this study,to provide references for the future construction of squares in this city. 展开更多
关键词 EASTERN RIVER culture Urban SQUARE Regional culture south-wind SQUARE
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Petrology and geochemistry of South Mid-Atlantic Ridge(19°S) lava flows:Implications for magmatic processes and possible plume-ridge interactions
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作者 Haitao Zhang Xuefa Shi +7 位作者 Chuanshun Li Quanshu Yan Yaomin Yang Zhiwei Zhu Hui Zhang Sai Wang Yili Guan Renjie Zhao 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第6期1953-1973,共21页
The South Mid-Atlantic Ridge(SMAR)19°S segment,approximately located along the line of Saint Helena volcanic chain(created by Saint Helena mantle plume),is an ideal place to investigate the issue whether the ridg... The South Mid-Atlantic Ridge(SMAR)19°S segment,approximately located along the line of Saint Helena volcanic chain(created by Saint Helena mantle plume),is an ideal place to investigate the issue whether the ridgehotpot interaction process affected the whole MAR.In this study,we present major and trace elemental compositions and Sr-Nd-Pb isotopic ratios of twenty fresh lava samples concentrated in a relatively small area in the SMAR 19°S segment.Major oxides compositions show that all samples are tholeiite.Low contents of compatible trace elements(e.g.,Ni=239-594 ppm and Cr=456-1010 ppm)and low Fe/Mn(54-67)and Ce/Yb(0.65-1.5)ratios of these lavas show that their parental magmas are partially melted by a spinel lherzolite mantle source.Using software PRIMELT3,this study obtained mantle potential temperatures(Tp)beneath the segment of1321-1348℃,which is lower relative to those ridges influenced by mantle plumes.The asthenospheric mantle beneath the SMAR 19°S segment starts melting at a depth of^63 km and ceases melting at^43 km with a final melting temperature of^1265℃.The extent of partial melting is up to 16%-17.6%with an average adiabatic decompression value of 2.6%/kbar.The correlations of major oxides(CaO/Al2 O3)and trace elements(Cr,Co,V)with MgO and Zr show that the parental magma experienced olivine and plagioclase fractional crystallization during its ascent to the surface.87Sr/86Sr(0.702398-0.702996),143 Nd/144 Nd(0.513017-0.513177)and 206Pb/204Pb(18.444-19.477)ratios of these lavas indicate the mantle source beneath the SMAR 19°S segment is composed of a three-component mixture of depleted MORB mantle,PREMA mantle,and HIMU mantle materials.The simple,binary mixing results among components from plume-free SMAR MORB,Saint Helena plume and Tristan plume show that asthenospheric mantle beneath the SMAR 19°S segment may be polluted by both Saint Helena and Tristan plume enriched materials.The abovementioned mantle potential temperatures,together with the low Saint Helena(<10%)and Tristan(<5%)components remaining in the asthenospheric mantle at present,show that the physically ridge-hotspot interactions at SMAR 19°S segment may have ceased.However,the trace element and SrNd-Pb isotopically binary mixing calculation results imply that these lavas tapped some enriched pockets left when Saint Helena and/or Tristan plume were once on the SMAR during earlier Atlantic rifted history. 展开更多
关键词 Magmatic process Mantle potential temperature Crystallization pressure Plume-ridge interaction south Mid-Atlantic Ridge
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Impacts of long-term ridge culture on aggregate stability in purple paddy soil of Sichuan basin
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作者 唐晓红 《Journal of Chongqing University》 CAS 2010年第4期185-194,共10页
Ridge culture is a special conservation tillage method, but the long-term influence of this tillage system on soil aggregate-size stability in paddy fields is largely unknown in southwest of China. The paper is to eva... Ridge culture is a special conservation tillage method, but the long-term influence of this tillage system on soil aggregate-size stability in paddy fields is largely unknown in southwest of China. The paper is to evaluate soil aggregate stability and to determine the relationship between soil organic carbon (SOC) and soil aggregate stability. Soil samples at 0 cm-20 cm layer were adopted from a long-term (16 a) field experiment including conventional tillage: plain culture, summer rice crop and winter upland crop under drained conditions (PUR-r); and conservation tillage: ridge culture without tillage, summer rice and winter fallow with floodwater layer annually (NTR-f), winter upland crop under drained conditions (NTR-r), and wide ridge culture without tillage, summer rice crop and winter upland crop under conditions (NTRw-r), respectively. Different pretreatments, such as slaking in fast wetting, wetting and subsequent slaking, were applied to simulate the breakdown mechanisms of aggregates in paddy soil. The results show that soil particles contents were mainly consisted of silt (0.050 mm to 1.000 mm) in fraction of 42.9% to 51.2%, sand (0.050 mm to 0.001 mm) in fraction of 28.0% to 31.8%, and clay (<0.001 mm) in fraction of 17.9% to 25.4%. The amount of aggregate-size was greatly observed in fraction of 2.000 mm-6.720 mm under ridge culture in paddy soil (more than 50$) under slaking and wetting pretreatment. The proportion of soil macro-aggregates (>0.250 mm) in conservation tillage was greatly higher than that in conventional tillage under subsequent fast slaking treatment. Minimal differences of aggregate stability between slaking in fast wetting and wetting were observed, while significant differences were found between ridge culture and plain culture. The aggregate stability under slaking treatment ranked in the order of NTR-r>NTRw-r> NTR-f > PUR-r, while under wetting was NTRw-r > NTR-r > NTR-f >PUR-r. There was a positive correlation between the aggregate stability and SOC concentration under wetting, and a low correlation was observed under slaking pretreatment. Soil exposure with tillage and lack of rice/rape-seed stubble inputs caused declines in aggregation and organic carbon, both of which make soil susceptible to water erosion. Adoption of ridge culture with no-tillage integrated with crop rotation and stubble mulch significantly altered soil organic concentration. It was a valuable conservation practice for soil aggregation and soil organic carbon sequestration on paddy soil. 展开更多
关键词 ridge culture ROTATION aggregate stability organic carbon paddy soil
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