期刊文献+
共找到3,114篇文章
< 1 2 156 >
每页显示 20 50 100
Hydrographic structure and circulation in the central area of the North Eastern Atlantic
1
作者 Xu Jianping Second Institute of Oceanography, State Oceanic Administration, P. O. Box 1207, Hangzhou 310012, China 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1992年第3期343-356,共14页
-On the basis of the hydrographic data observed within the Canary Basin in autumn 1985, temperature-salinity properties, distributions of water masses and barocltne flow field, as well as the volume transports in this... -On the basis of the hydrographic data observed within the Canary Basin in autumn 1985, temperature-salinity properties, distributions of water masses and barocltne flow field, as well as the volume transports in this area are described more detailly. The analyses indicate that the activity in the waters of the Canary Basin is mainly attributed to the interleaving and mixing between the originated water masses (e. g. Surface Water, North Atlantic Central Water, Mediterranean Water and Deep Water) and the modified water masses (Subpolar Mode Water, Labrador Sea Water and Antarctic Intermediate Water) from the outside of the study area and the variation of themselves. The east recirculation of the Subtropic Gyre in the North Atlantic consists of Azores Current and Canary Current.Azores Current is formed with several flow branches around the Azores Island, while the main flow lies at 35?N south of the Azores Island. It begins to diverge near the 15?W. The return flow found off the Portugal coast may be its northern branch. The southern invasion of the Labrador Sea Water and the Subpolar Mode Water are prevented by Azores front which serves an obvious boundary separating the North Western Atlantic (Central) Water and the North Eastern Atlantic (Central) Water. 展开更多
关键词 Hydrographic structure and circulation in the central area of the North Eastern Atlantic area
下载PDF
Geochemical characteristics of soil selenium and evaluation of Serich land resources in the central area of Guiyang City,China 被引量:8
2
作者 Ziping Pan Shaolin He +3 位作者 Chaojin Li Wei Men Chengzhi Yan Fang Wang 《Acta Geochimica》 EI CAS CSCD 2017年第2期240-249,共10页
Based on the results of multipurpose regional geochemical surveys of the Guizhou Province, geochemical characteristics of soil Se and Se-rich land resources in the central area of Guiyang City were studied and evaluat... Based on the results of multipurpose regional geochemical surveys of the Guizhou Province, geochemical characteristics of soil Se and Se-rich land resources in the central area of Guiyang City were studied and evaluated.Major conclusions are as follows:(1) the Se content in surface soil of the central area of Guiyang City was 0.17–2.89 mg kg^(-1), and the average was 0.78 mg kg^(-1), which were respectively 2.6 and 3.9 times of the national background value of soil and the world background value of soil.The Se content in deep soil was 0.11–1.48 mg kg^(-1), and the average was 0.44 mg kg^(-1), which were respectively 1.5 and2.2 times of the national background value of soil and the world background value of soil. The soil Se content decreased with the increase in the soil depth on the vertical profile, and the surface soil had a higher Se content.(2)Distribution of Se content was mainly affected by parent material, physicochemical properties of soil and other components, soil type, and land use type. Parent material played a key role, as the soil Se content was mainly originated from parent rock and increased with the background value of Se in parent rock, physicochemical properties of soil and other components had certain influences upon the Se content. Se was shown to have a significant linear positive correlation with S and organic carbon but no significant correlation with p H value. Se content varied with different types of soil as follows: skeleton soil > yellow soil > paddy soil > limestone soil > purple soil. Land use type also hadcertain influences upon the soil Se content as follows: dry land > construction land > garden plot > grassland =garden plot > forest land.(3) Taking 0.4 mg kg^(-1)B x(Se) <3.0 mg kg^(-1) as the standard for Se-rich soil, Se-rich soil of the study area covered an area of 2224 km^2 and 92.5% of the total area; the remaining is general soil. The study area had no Se-excess soil. Therefore, the central area of Guiyang City has a high proportion of Se-rich land, a large area of Serich land resources, and a moderate selenium enrichment strength, which have been rarely seen anywhere and provide advantageous resources for the development of Se-rich featured agriculture. 展开更多
关键词 土地资源评价 地球化学特征 市中心区 土壤硒 贵阳市 区域地球化学调查 土壤理化性质 土地利用类型
下载PDF
Burial fluxes and sources of organic carbon in sediments of the central Yellow Sea mud area over the past 200 years 被引量:3
3
作者 YANG Shu YANG Qian +3 位作者 LIU Sai CAI Deling QU Keming SUN Yao 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2015年第10期13-22,共10页
Long-term changes of composition, sources and burial fluxes of TOC (total organic carbon) in sediments of the central Yellow Sea mud area and their possible affecting factors are discussed in this paper. Firstly, si... Long-term changes of composition, sources and burial fluxes of TOC (total organic carbon) in sediments of the central Yellow Sea mud area and their possible affecting factors are discussed in this paper. Firstly, similarity analysis is employed to confirm that the carbon burial features resulted from two collected cores are typical in the central Yellow Sea mud area where YSWC (Yellow Sea Warm Current) is prevalent. On this basis, the burial flux of TOC here was considered to be 235.5-488.4 pmol/(cm^2.a) since the first industrial revolution, accounting for about 70%-90% among burial fluxes of TC (total carbon) in the sediments. Compared TOC/TC ratio in the two cores with that in other marine sediments worldwide, we suggest that the growth of calcareous/non-calcareous organisms and dissolution of IC (inorganic carbon) are important factors controlling the TOC/TC ratio in sediment. Results of two-end mixed model based on fi13C data indicate that marine-derived organic carbon (OCa) is the main part among total burial organic carbon which accounts for a ratio over 85%. Due to the high TOC/TC ratio in the two cores, TC in the sediments also mainly exists as OCa, and the proportion of OCa is about 60%-80%. Away from the shore and relatively high primary production in upper waters are the main reasons that OCa is predominant among all burial OC in sediments of the central Yellow Sea mud area. Burial of OC in this mud area is probably mainly influenced by the human activities. Although the economic development during the late 19th century caused by the first industrial revolution in China did not obviously increase the TOC burial fluxes in the sediments, the rise of industry and agriculture after the founding of new China has clearly increased the TOC burial flux since 1950s. Otherwise, we also realize that among TC burial fluxes, TIC account for about 10%-30% in sediments of the central Yellow Sea mud area, so its burial could not be simply ignored here. Distinct from TOC burial, long-term TIC burial fluxes variations relate with climate changes more closely: the East Asian summer monsoon may influence the strength of the Huanghe River (Yellow River) flood, which could further affect the transport of terrestrial IC from land to the central Yellow Sea as well as the burial of these IC in the sediments. 展开更多
关键词 the central Yellow Sea mud area organic carbon burial flux source long-term changes human activities
下载PDF
Effects of Land Use Change on Eco-environment in Hilly Area of Central Sichuan Basin——A Case Study of Yanting County, Sichuan Province 被引量:2
4
作者 Luo Huai-liang, Zhu Bo, Chen Guo-jie, Gao Mei-rongInstitute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, Sichuan, China College of Resources and Environment, Sichuan Normal University, Chengdu 610066, Sichuan, China 《Wuhan University Journal of Natural Sciences》 CAS 2003年第03B期981-986,共6页
With the artificial alder and cypress mixed forest being planted, there has been a marked land use change since 1970s' in Hilly Area of Central Sichuan Basin, China. Data from meteorological observations or posts ... With the artificial alder and cypress mixed forest being planted, there has been a marked land use change since 1970s' in Hilly Area of Central Sichuan Basin, China. Data from meteorological observations or posts operated over long time, measurement and calculation of NPP (net primary production) and biomass of biological community, and analysis of soil organic matter content show that the artificial alder and cypress mixed forest has outstanding eco-environmental effect: adjusting local climate, raising soil fertility, alleviating menace of drought, and raising NPP and biomass of biological community. It is very beneficial for improving ecological environment to afforest artificial alder and cypress mixed forest in populous Hilly Area of Central Sichuan Basin, China. Key Words: land use/land cover change (LUCC); eco-environmental effect; Hilly Area of Central Sichuan Basin; the artificial alder and cypress mixed forest 展开更多
关键词 of as for Sichuan Province Effects of Land Use Change on Eco-environment in Hilly area of central Sichuan Basin A Case Study of Yanting County on ECO
下载PDF
The difference analysis of physical-mechanical properties of sediments in the central South Yellow Sea and Zhe-Min coastal area in China 被引量:1
5
作者 XU Yuanqin LI Ping +4 位作者 LI Peiying DU Jun LIU Lejun GAO Wei LIU Jie 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2017年第7期77-85,共9页
The difference analysis of physical-mechanical properties of muddy sediments is made in the central South Yellow Sea and the Zhe-Min(Zhejiang Province to Fujian Province of China) coastal area. The results show that... The difference analysis of physical-mechanical properties of muddy sediments is made in the central South Yellow Sea and the Zhe-Min(Zhejiang Province to Fujian Province of China) coastal area. The results show that sediments in the two regions are both dominated by mud. There are perfect negative power function correlations between the water content and the density, the compression coefficient and the compression modulus; a good positive power function correlation between the liquid limit and the plastic limit, a perfect positive linear correlation between the water content and the void ratio, and a perfect polynomial function correlation between the miniature vane shear strength and the pocket penetration resistance. In general, compared with sediments in the Zhe-Min coastal area, sediments in the central South Yellow Sea possess high water content, high void ratio,low density, high plasticity, high compressibility, low shear strength. The causes of the differences between physical-mechanical properties of sediments are analyzed from the topographic features, material sources,hydrodynamic conditions, deposition rate, and material composition. Compared with the Zhe-Min coastal area,the central South Yellow Sea is far from the Mainland and low-lying; has poor hydrodynamic condition; the materials diffused to the area are less and dominated by fine clay, have the high content of smectite and organic matters. These factors lead to sediments of the central South Yellow Sea has the higher water content, the higher plasticity, the lower density, and the lower strength than sediments in the Zhe-Min coastal area. 展开更多
关键词 sediment Zhe-Min coastal area central South Yellow Sea physical-mechanical properties difference analysis
下载PDF
Continental reconstruction and metallogeny of the Circum-Junggar areas and termination of the southern Central Asian Orogenic Belt 被引量:17
6
作者 Wenjiao Xiao Min Sun M.Santosh 《Geoscience Frontiers》 SCIE CAS CSCD 2015年第2期137-140,共4页
Continental reconstructions in Central Asia are represented by orogenesis along some large orogenic belts in the Altaid collage (Fig. 1 ) or Central Asian Orogenic Belt (CAOB), which separate the East European and... Continental reconstructions in Central Asia are represented by orogenesis along some large orogenic belts in the Altaid collage (Fig. 1 ) or Central Asian Orogenic Belt (CAOB), which separate the East European and Siberian cratons to the north from the Tarim and North China cratons to the south ($eng0r et al,, 1993; Jahn et al., 2004; Windley et al., 2007; Qu et al., 2008; Xiao et al., 2010; Xiao and Santosh, 2014). The Altaid Collage was characterized by complex long tectonic and structural evolution from at least ca. 1.0 Ga to late Paleozoic-early Mesozoic with considerable continental growth (Khain et al., 2002; Jahn et al., 2004; Xiao et al., 2009, 2014; KrOner et al., 2014), followed by Cenozoic intracontinental evolution related to far-field effect of the collision of the In- dian Plate to the Eurasian Accompanying with these complex world-class ore deposits developed 2001; Goldfarb et al., 2003, 2014). Plate (Cunningham, 2005). geodynamic evolutions, many (Qin, 2000; Yakubchuk et al,2001; Goldfarb et al., 2003, 2014). 展开更多
关键词 Continental reconstruction and metallogeny of the Circum-Junggar areas and termination of the southern central Asian Orogenic Belt
下载PDF
Bidding Scheme Design of Central Recreational Area for Xiaogan Linkong Economic Zone
7
作者 WANG Ai'guo SUN Ti 《Journal of Landscape Research》 2016年第5期48-52,共5页
This paper elaborated the bidding scheme design of the Central Recreational Area in Linkong Economic Zone from the perspectives of site analysis, determination of properties, design theme and principle, scheme layout ... This paper elaborated the bidding scheme design of the Central Recreational Area in Linkong Economic Zone from the perspectives of site analysis, determination of properties, design theme and principle, scheme layout and conception, in order to explore the potential enlightenments of the scheme design process, and disclose significance of site analysis and its close relationship with the scheme design. 展开更多
关键词 Linkong Economic Zone central Recreational area Bidding scheme Water show Phoenix dancing
下载PDF
Spatial and Temporal Distributions of Soil Organic Matter in the Mixed Plantations of Alder and Cypress in the Hilly Areas of Central Sichuan Basin
8
作者 WU Pengfei ZHU BO +1 位作者 YANG Yuanli WANG Xiaoguo 《Wuhan University Journal of Natural Sciences》 EI CAS 2006年第4期1021-1027,共7页
The investigation was conducted on the spatial and temporal distributions of soil organic mater (SOM) in the mixed plantations of alder (Aluns crernastogyne) and cypress (Cupressus funebris ) (MPAC), which dis... The investigation was conducted on the spatial and temporal distributions of soil organic mater (SOM) in the mixed plantations of alder (Aluns crernastogyne) and cypress (Cupressus funebris ) (MPAC), which distributed in the hilly areas of central Sichuan Basin (HACSB). The results show that: (1) the spatial distribution of SOM among different sites at the same age are not significant before 15-year-old, but significant at 20-year-old, and not significant again after 25-year-old; (2) the SOM contents in 0-15 cm and 15-30 cm layers increase sharply from 10- to 15-year-old, and decline gradually from 15- to 30- year-old; the SOM contents of the 30-year-old PCP were 80. 38% and 78.42% higher than that of the 10-year-old, but 29.16% and 53.37% lower than that of 15-year-old in the 0-15 cm and 15-30 cm layers, respectively. The decrease of SOM contents would lead to the degradation of soil fertility and the decline of forest productivity. 展开更多
关键词 hilly areas of central Sichuan mixed plantations of alder and cypress soil organic matter spatial distributions temporal dynamics
下载PDF
Sensitivity Assessment and Optimization Strategy of Climatic Environment in Central Urban Area of Beijing
9
作者 YANG Xin GAO Wenwen LI Nana 《Journal of Landscape Research》 2021年第6期1-4,共4页
As one of the methods of urban environmental assessment,sensitivity assessment of urban climatic environment can accurately reflect the problem areas of current urban climate and built environment through visual means... As one of the methods of urban environmental assessment,sensitivity assessment of urban climatic environment can accurately reflect the problem areas of current urban climate and built environment through visual means,and help cities to carry out sustainable transformation and renewal in the stock era to optimize the living environment.Taking the central urban area of Beijing as the research object,the sensitivity of climatic environment was evaluated by meteorological data and built environment element data.The results showed that the distribution of sensitive units showed a centrifugal radiation pattern of"high in the center and low in the periphery".Block units with high climate sensitivity were mostly concentrated in Xicheng District and Dongcheng District,accounting for 93%of the total number of units.Further research showed that complex built environment and lack of elements to regulate climatic environment were the main reasons for the poor local climatic environment in the region with high climate sensitivity.Finally,a comprehensive evaluation of the remolding capacity,renewal potential and future development intensity of different grades of climate sensitive units was given.The results will provide scientific reference for urban renewal and reconstruction under climatic and environmental changes,so as to promote urban sustainable development and improvement of living environment. 展开更多
关键词 central urban area of Beijing Climatic environment Sensitivity Optimization guideline
下载PDF
Ecological Function Value of Tropical Forests in the Central Mountainous Areas of Hainan Island
10
作者 Jing GAO Zuguang ZHOU 《Asian Agricultural Research》 2013年第11期103-105,108,共4页
The integrated value of the ecological function of tropical forests in the central mountainous areas of Hainan Island was 33.064 8 billion yuan/a in 2010(soil improvement,soil consolidation,soil nutrient maintenance,w... The integrated value of the ecological function of tropical forests in the central mountainous areas of Hainan Island was 33.064 8 billion yuan/a in 2010(soil improvement,soil consolidation,soil nutrient maintenance,water storage and moisture regulation,water purification,carbon sequestration,oxygen releasing,air purification,biodiversity conservation,eco-tourism),equivalent to 16.1%of GDP in Hainan Province this year(205.212 billion yuan).The tropical forests in the central mountainous areas of Hainan Island make great contribution to Hainan Island's ecology,and play an important role in maintaining the stability of the ecological environment in Hainan Island.Through the understanding of major ecological function value of tropical forests,it is necessary to make people cherish the tropical forests in the central ecological function conservation areas of Hainan Province,and spontaneously throw themselves into the ecological environment protection and construction,to promote the rapid and sustainable development of construction in Hainan Province as an international tourism island. 展开更多
关键词 central mountainous areas TROPICAL FORESTS Ecologi
下载PDF
Assessing Spatio-temporal Characteristics of Water Storage Changes in the Mountainous Areas of Central Asia Based on GRACE
11
作者 ZHANG Pengfei CHEN Xi +2 位作者 BAO Anming LIU Tie Felix NDAYISABA 《Chinese Geographical Science》 SCIE CSCD 2017年第6期918-933,共16页
The mountainous areas of Central Asia provide substantial water resources, and studying change in water storage and the impacts of precipitation and snow cover in the mountain ranges of Central Asia is of the greatest... The mountainous areas of Central Asia provide substantial water resources, and studying change in water storage and the impacts of precipitation and snow cover in the mountain ranges of Central Asia is of the greatest importance for understanding regional water shortages and the main factors. Data from the GRACE(Gravity Recovery and Climate Experiment) satellites, precipitation products and snow-covered area data were used to analyze the spatio-temporal characteristics of water storage changes and the effects of precipitation and snow cover from April 2002 to December 2013. The results were computed for each mountain ranges, and the following conclusions were drawn. The water storage in the mountainous areas of Central Asia as a whole increases in summer and winter, whereas it decreases in autumn. The water storage is affected by precipitation to some extent and some areas exhibit hysteresis. The area of positive water storage changes moves from west to east over the course of the year. The water storage declined during the period 2002–2004. It then returned to a higher level in 2005–2006 and featured lower levels in 2007–2009 Subsequently, the water storage increased gradually from 2010 to 2013. The Eastern Tianshan Mountains and Western Tianshan Mountain subzones examined in this study display similar tendencies, and the trends observed in the Karakorum Mountains and the Kunlun Mountains are also similar. However, the Eastern Tianshan Mountains and Western Tianshan Mountains were influenced by precipitation to a greater degree than the latter two ranges. The water storage in Qilian Mountains showed a pronounced increasing trend, and this range is the most strongly affected by precipitation. Based on an analysis of all investigated subzones, precipitation has the greatest influence on total water storage relative to the snow covered area in some areas of Central Asia. The results obtained from this study will be of value for scientists studying the mechanisms that influence changes in water storage in Central Asia. 展开更多
关键词 水资源变化 中亚地区 GRACE 时空特性 山区 特征评价 STORAGE 喀喇昆仑山
下载PDF
Petrogenesis and Tectonics of the Naruo Porphyry Cu(Au) Deposit Related Intrusion in the Duolong Area,Central Tibet 被引量:9
12
作者 DING Shuai CHEN Yuchuan +3 位作者 TANG Juxing ZHENG Wenbao LIN Bin YANG Chao 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第2期581-601,共21页
The Duolong area is the most important part of the Western Bangong-Nujiang Suture Zone porphyry Cu(Au) metallogenic belt, in Tibet, China. Here new detailed data are presented from LAICP-MS zircon U-Pb, whole-rock g... The Duolong area is the most important part of the Western Bangong-Nujiang Suture Zone porphyry Cu(Au) metallogenic belt, in Tibet, China. Here new detailed data are presented from LAICP-MS zircon U-Pb, whole-rock geochemical, and in-situ zircon Hf isotope analyses for igneous rocks in the large Naruo deposit(2.51 Mt of Cu and 82 t of Au) which is located ~2 km NE of the Duolong(Duobuza and Bolong) super-large gold-rich porphyry copper deposit. We integrated our results with previous research of other porphyry deposits in the Duolong area and have identified the timing, geodynamic setting, and petrogenesis of the mineralization-associated magmatic events. Based on the measurements, the Duolong area porphyry Cu(Au) deposit formations are associated with Early Cretaceous intermediate-felsic magmatism, which is consistent with U-Pb zircon ages of 120 Ma. All the main intrusive rocks in the ore-concentrated area have similar lithogeochemical characteristics; they show a relative enrichment in both light rare earth elements(LREEs) and large-ion lithophile elements(LILEs: Rb, Ba, K, etc.) and relative depletion in both heavy rare earth elements(HREEs) and high field strength elements(HFSEs: Nb, Ta, Zr, Hf, etc.). Moreover, the granite porphyry shows positive εHf(t) values between 1.38–7.37 suggesting that magmas were potentially derived from the partial melting of a depleted mantle wedge that had been metasomatized by subducted slab-derived fluids or melts. This paper points out that the formation of the porphyry-epithermal Cu(Au) deposit in the Duolong area was dominated by northward subduction of the Bangongco Tethys Plate beneath the Qiangtang block in the Early Cretaceous(124–114 Ma), when the subducted oceanic crust reached 50–70 km underground and generated different degrees of phase transformation, which lead to a melt produced by dehydration of amphibole minerals, a metasomatized mantle wedge, and induced mantle partial melting that produced the magma. Those deposits occurred in a continental arc tectonic setting, which is similar to the continental margin arc environment of the ocean-continent subduction setting of the Andes metallogenic belt in South America. 展开更多
关键词 geochemical signatures zircon U-Pb Hf isotope Duolong area continental arc depleted mantle central Tibet Proto-Tethys
下载PDF
Thinking on Establishing Free Trade Area of Central Asia
13
作者 Lunzhi He Ping Cai 《Chinese Business Review》 2003年第4期27-32,共6页
下载PDF
Road Centrality and Landscape Spatial Patterns in Wuhan Metropolitan Area,China 被引量:9
14
作者 LIU Yaolin WANG Huimin +3 位作者 JIAO Limin LIU Yanfang HE Jianhua AI Tinghua 《Chinese Geographical Science》 SCIE CSCD 2015年第4期511-522,共12页
Road network is a corridor system that interacts with surrounding landscapes,and understanding their interaction helps to develop an optimal plan for sustainable transportation and land use.This study investigates the... Road network is a corridor system that interacts with surrounding landscapes,and understanding their interaction helps to develop an optimal plan for sustainable transportation and land use.This study investigates the relationships between road centrality and landscape patterns in the Wuhan Metropolitan Area,China.The densities of centrality measures,including closeness,betweenness,and straightness,are calculated by kernel density estimation(KDE).The landscape patterns are characterized by four landscape metrics,including percentage of landscape(PLAND),Shannon′s diversity index(SHDI),mean patch size(MPS),and mean shape index(MSI).Spearman rank correlation analysis is then used to quantify their relationships at both landscape and class levels.The results show that the centrality measures can reflect the hierarchy of road network as they associate with road grade.Further analysis exhibit that as centrality densities increase,the whole landscape becomes more fragmented and regular.At the class level,the forest gradually decreases and becomes fragmented,while the construction land increases and turns to more compact.Therefore,these findings indicate that the ability and potential applications of centrality densities estimated by KDE in quantifying the relationships between roads and landscapes,can provide detailed information and valuable guidance for transportation and land-use planning as well as a new insight into ecological effects of roads. 展开更多
关键词 景观空间格局 市区道路 SHANNON多样性指数 武汉 土地利用规划 可持续交通 核密度估计 空间密度
下载PDF
大型城镇集中安置区搬迁移民生计资本组合对家庭收入影响机理的实证研究
15
作者 汪磊 张薇薇 汪霞 《贵州财经大学学报》 北大核心 2024年第3期81-91,共11页
易地搬迁移民已成为防止规模性返贫的重要群体。当前,搬迁移民面临着就业市场风险增大,生计资本存量减少以及家庭增收困难等现实问题,优化移民生计资本内部结构,发挥生计资本间的组合效应,提升生计资本组合对移民家庭收入的贡献作用是... 易地搬迁移民已成为防止规模性返贫的重要群体。当前,搬迁移民面临着就业市场风险增大,生计资本存量减少以及家庭增收困难等现实问题,优化移民生计资本内部结构,发挥生计资本间的组合效应,提升生计资本组合对移民家庭收入的贡献作用是解决上述问题的重要途径。学界当前与易地搬迁相关的研究多聚焦分析移民生计资本对家庭总收入的作用机制,较少基于结构功能理论视角,从实证层面探讨生计资本组合对家庭不同收入来源的影响及其相互作用机制。本文以贵州省大型城镇集中安置区移民为研究对象,首先测算移民家庭生计资本,分别采用OLS和分位数回归分析生计资本与家庭收入之间的作用机理,然后采用多元线性回归模型测算生计资本间的互补效应和替代效应,构建了移民家庭收入与生计资本组合之间的矩阵分析模型,分别应用tobit和logit回归进行实证检验,并剖析了不同维度下不同生计资本组合对不同类型收入的影响。研究结果表明:(1)移民生计资本总量有助于提升家庭收入水平。在后搬迁时代,自然资本对家庭收入的边际贡献最小,而社会资本对家庭收入呈现负向影响。(2)五大资本中的人力资本与自然资本、物质资本、社会资本以及金融资本之间存在着普适性互补效应,金融资本与社会资本间存在替代效应。(3)互补性生计资本值越大,移民家庭工资收入和财产收入越高;互补性和替代性资本量均较低的家庭主要以获得转移性收入维持生计。 展开更多
关键词 大型城镇集中安置区 互补性生计资本 替代性生计资本 家庭收入结构
下载PDF
中央苏区农业科技的研究与推广
16
作者 庞振宇 《农业考古》 北大核心 2024年第1期54-62,共9页
发展农业生产不仅需要开展土地革命来激发苏区群众的积极性,还需要以农业科技的研究与推广来提高农业生产力水平。在中央苏区,中国共产党和苏维埃政府创办农事试验场、农业学校和农产品展览所,研究农业科学技术,在选育优良品种、改良土... 发展农业生产不仅需要开展土地革命来激发苏区群众的积极性,还需要以农业科技的研究与推广来提高农业生产力水平。在中央苏区,中国共产党和苏维埃政府创办农事试验场、农业学校和农产品展览所,研究农业科学技术,在选育优良品种、改良土壤、防治病虫害、兴修水利、改良农具、植树造林等方面积极推广新技术和新经验,取得了很好的成效。农业科技的研究与推广,在解决中央苏区粮食安全等方面发挥了重要作用,这是中国共产党领导农业科技事业的开端。 展开更多
关键词 苏区 农业科技 研究机构 成效
下载PDF
川中蓬莱气区龙王庙组储层特征及其与磨溪—高石梯地区对比
17
作者 邢凤存 刘子琪 +6 位作者 钱红杉 李勇 周刚 张亚 黄茂轩 李成龙 龙虹宇 《石油实验地质》 CAS CSCD 北大核心 2024年第3期510-521,共12页
川中蓬莱气区下寒武统龙王庙组钻遇良好碳酸盐岩储层,天然气显示好,成为继川中地区安岳大气田后龙王庙组重点勘探区之一,但储层发育规律不明制约了勘探部署。基于最新的钻井及分析测试等资料,系统分析了蓬莱气区龙王庙组储层特征及主控... 川中蓬莱气区下寒武统龙王庙组钻遇良好碳酸盐岩储层,天然气显示好,成为继川中地区安岳大气田后龙王庙组重点勘探区之一,但储层发育规律不明制约了勘探部署。基于最新的钻井及分析测试等资料,系统分析了蓬莱气区龙王庙组储层特征及主控因素。研究认为,蓬莱气区龙王庙组具有陆源碎屑与碳酸盐混合沉积背景,储层主要分布在龙王庙组中上部;储集岩石类型主要为(残余)颗粒白云岩和结晶白云岩;储集空间类型主要为粒间溶孔、粒内溶孔、晶间溶孔及微裂缝;以低孔低渗储层为主,储层厚度主要介于10~42 m之间。储层发育受控于层序地层、岩性及成岩作用等,进积型准层序组和准层序中上部的(残余)颗粒白云岩和结晶白云岩是储层发育主要部位,大气淡水溶蚀、油气溶蚀作用及破裂作用是核心建设性成岩作用。对比安岳大气田主体区磨溪—高石梯地区,认为储层主控因素相近,主要受颗粒白云岩、溶蚀作用、破裂作用等控制,但蓬莱气区龙王庙组储层具有灰质含量高、陆源碎屑含量多、准同生期暴露弱等特点,寻找准同生期暴露的高能颗粒白云岩和细晶白云岩及表生岩溶改造的白云岩是蓬莱气区重点关注的储层目标。 展开更多
关键词 储层特征 主控因素 龙王庙组 下寒武统 蓬莱气区 磨溪—高石梯地区 川中地区
下载PDF
2024年中央一号文件的突出亮点 被引量:1
18
作者 姜长云 《农村金融研究》 北大核心 2024年第2期3-13,共11页
2024年中央一号文件以习近平新时代中国特色社会主义思想为指导,为2024年乃至今后一段时期的“三农”工作进行了系统部署和具体安排,呈现了一系列突出亮点。即:凸显了贯彻中央经济工作会议精神和深化对“三农”工作的规律性认识,明确了... 2024年中央一号文件以习近平新时代中国特色社会主义思想为指导,为2024年乃至今后一段时期的“三农”工作进行了系统部署和具体安排,呈现了一系列突出亮点。即:凸显了贯彻中央经济工作会议精神和深化对“三农”工作的规律性认识,明确了学习运用“千万工程”经验引领乡村全面振兴的要求,重视运用战略思维和改革创新,统筹强化软政策引领与硬政策支撑作用,坚持守正创新,确保国家粮食安全有新招,确保不发生规模性返贫底线更明确措施更有力,强调以坚持“三个提升”为重点建设宜居宜业和美乡村。 展开更多
关键词 中央一号文件 “三农”工作 推进乡村全面振兴 “千万工程”
下载PDF
抗VEGF药物联合全视网膜光凝治疗糖尿病视网膜病变的效果和预后分析
19
作者 汤畴旺 张采华 郑上椿 《中国卫生标准管理》 2024年第12期141-144,共4页
目的探讨抗血管内皮生长因子(vascular endothelial growth factor,VEGF)药物联合全视网膜光凝(panretinal photocoagulation,PRP)治疗糖尿病视网膜病变的效果和预后分析。方法选取三明市第二医院2020年1月—2023年1月收治的50例糖尿病... 目的探讨抗血管内皮生长因子(vascular endothelial growth factor,VEGF)药物联合全视网膜光凝(panretinal photocoagulation,PRP)治疗糖尿病视网膜病变的效果和预后分析。方法选取三明市第二医院2020年1月—2023年1月收治的50例糖尿病视网膜病变者(78眼),以随机数字表法分为2组,各25例(39眼)。对照组患者给予PRP治疗,研究组给予抗VEGF药物联合PRP治疗。比较2组术前、术后恢复指标,统计患者治疗后的不良反应,评价治疗效果。结果术后,2组最佳矫正视力(best correct vision acuity,BCVA)优于术前,视网膜新生血管(retinal neovascularization,RNV)面积、中央视网膜厚度(central retinal thickness,CRT)低于术前,且研究组BCVA高于对照组;RNV面积、CRT低于对照组,差异有统计学意义(P<0.05);研究组并发症总发生率为5.13%,低于对照组的23.08%,差异有统计学意义(P<0.05);研究组治疗总有效率为94.97%,高于对照组的79.49%,差异有统计学意义(P<0.05)。结论糖尿病视网膜病变以抗VEGF药物联合PRP治疗可改善术后BCVA,减少RNV面积、CRT,降低并发症发生率,提升治疗效果。 展开更多
关键词 抗VEGF药物 全视网膜光凝 糖尿病视网膜病变 中央视网膜新生血管面积 治疗效果 预后效果
下载PDF
中国共产党在中央苏区时期法制建设的民主特质及立法精神
20
作者 张师伟 孙亚亚 《西华师范大学学报(哲学社会科学版)》 2024年第2期77-84,共8页
习近平总书记在中国共产党第二十次全国代表大会的报告中强调:“坚持共产党的领导”是“中国式现代化的本质要求”。马克思主义传入中国及中国共产党的成立,开辟了中国现代化建设的新方向。中国共产党在中央苏区时期进行了现代化国家建... 习近平总书记在中国共产党第二十次全国代表大会的报告中强调:“坚持共产党的领导”是“中国式现代化的本质要求”。马克思主义传入中国及中国共产党的成立,开辟了中国现代化建设的新方向。中国共产党在中央苏区时期进行了现代化国家建设的重要尝试,在法制建设方面贯彻了马克思主义人民民主的原则,体现了充分的民主性。这一时期,中国共产党制定和颁行的一系列法律、法令、条例、训令,以马克思主义人民民主思想为根本指导思想,以解放中国社会的广大劳苦人民群众、建立工人和农民的民主专政为根本目的,同时在立法、执法、司法过程中又特别注重人民对权力的民主监督。中国共产党在苏维埃时期的法制建设实践,体现着中国共产党最早的民主政治理念,是当代中国社会主义法治的源头所在。 展开更多
关键词 中国共产党 中央苏区 法制建设 人民民主 民主性
下载PDF
上一页 1 2 156 下一页 到第
使用帮助 返回顶部