期刊文献+
共找到1,708篇文章
< 1 2 86 >
每页显示 20 50 100
Ecological risk assessment and early warning of heavy metal cumulation in the soils near the Luanchuan molybdenum polymetallic mine concentration area,Henan Province,central China 被引量:13
1
作者 Zhen-yu Chen Yuan-yi Zhao +3 位作者 Dan-li Chen Hai-tao Huang Yu Zhao Yu-jing Wu 《China Geology》 CAS CSCD 2023年第1期15-26,共12页
The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great sign... The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great significance to study the ecological risk and the accumulation trends of heavy metals in the soil of mining areas for scientific prevention and control of heavy metal pollution.Taking the Taowanbeigou River Basin in the mine concentration area as the research object,the ecological pollution risk and cumulative effect of heavy metals in the soil of the basin were studied by using the comprehensive pollution index method,potential ecological risk assessment method and geoaccumulation index method.On this basis,the cumulative exceeding years of specific heavy metals were predicted by using the early warning model.The comprehensive potential ecological risk of heavy metals in the soil near the Luanchuan mine concentration area is moderate,and the single element Cd is the main ecological risk factor,with a contribution rate of 53.6%.The overall cumulative degrees of Cu and Pb in the soil are“none-moderate”,Zn and Cd are moderate,Mo has reached an extremely strong cumulative level,Hg,As and Cr risks are not obvious,and the overall cumulative risks order is Mo>Cd>Zn>Cu>Pb>Hg.According to the current accumulation rate and taking the risk screening values for soil contamination of agricultural land as the reference standard,the locations over standard rates of Cu,Zn and Cd will exceed 78%in 90years,and the over standard rate of Pb will reach approximately 57%in 200 years.The cumulative exceeding standard periods of As,Cr and Hg are generally long,which basically indicates that these elements do not pose a significant potential threat to the ecological environment.Mining activities will accelerate the accumulation of heavy metals in soil.With the continuous development of mining activities,the potential pollution risk of heavy metals in the soil of mining areas will also increase. 展开更多
关键词 Soil Heavy metals Mining impact Cumulative effect Potential ecological risk Cumulation early warning Luanchuan mine concentration area Environmental geological survey engineering
下载PDF
Experimental Study on the Chloride Ion Concentration of Cement Pastes Prepared with Limestone Powder
2
作者 ZHANG Kaijian HUANG Zeping +1 位作者 JIA Xuxiu WANG Dehui 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第6期1474-1483,共10页
To investigate the impact of limestone powder on the chloride ion concentration coefficient of cement pastes,various techniques such as scanning electron microscopy(SEM),X-ray diffraction(XRD),thermogravimetric analys... To investigate the impact of limestone powder on the chloride ion concentration coefficient of cement pastes,various techniques such as scanning electron microscopy(SEM),X-ray diffraction(XRD),thermogravimetric analysis(TGA),and mercury-porosimetry(MIP)were employed in this paper.The findings demonstrate that the creation of Friedel's salt is inversely associated with the addition of limestone powder,that is,Friedel's salt production is lessened by adding more limestone powder,however,the coefficient of chloride ion concentration initially decreased and then increased again,as does the porosity,and most likely the pore size as well.The specific surface area of limestone powder has increased,and the content of Friedel’s salt increased first and then decreased.However,the shifting trend of Friedel's salt and chloride ion concentration coefficient is in direct opposition,and the pore structure was therefore significantly enhanced.The results of this study offer robust theoretical backing for the inclusion of limestone powder in concrete and provide a positive assessment of its potential applications. 展开更多
关键词 limestone powder specific surface area CONTENT friedel's salt chloride ion concentration coefficient
下载PDF
Research on Vegetation Recovery of Mountainous Parks in City-and-town Concentration Areas in China 被引量:1
3
作者 赵雯瑾 王思麒 +1 位作者 李彬 罗言云 《Journal of Landscape Research》 2012年第2期38-40,共3页
Based on the analysis of features and problems of green lands in mountainous parks in towns concentration areas,the paper has illustrated the significance for vegetations'recovery.By taking Tashan Park in Neijiang... Based on the analysis of features and problems of green lands in mountainous parks in towns concentration areas,the paper has illustrated the significance for vegetations'recovery.By taking Tashan Park in Neijiang City for example,it has investigated the eco-environment and vegetations of this park.The results show that its terrain is precipitous,eco-environment is weak,slope vegetation is less,rocks'exposing rate is high and community structure is simple.In view of the survey results,it has proposed two methods for vegetation recovery that are natural recovery and artificial recovery.In particular,it has explored how to conduct vegetation recovery on green lands of different gradients of slopes by using plants'selection and community disposition. 展开更多
关键词 VEGETATION recovery Mountainous parks City-and-town concentration areas
下载PDF
Deep Structural Framework and Genetic Analysis of Gold Concentration Areas in the Northwestern Jiaodong Peninsula, China: A New Understanding based on High-Resolution Reflective Seismic Survey 被引量:23
4
作者 YU Xuefeng SHAN Wei +8 位作者 XIONG Yuxin GENG Ke SUN Yuqin CHI Naijie GUO Baokui LI Dapeng LI Hongkui SONG Yingxin YANG Deping 《Acta Geologica Sinica(English Edition)》 CAS CSCD 2018年第5期1823-1840,共18页
The gold concentration areas in the northwestern Jiaodong Peninsula constituted an important gold metallogenetic region in Eastern China during the Mesozoic. The deep geological bodies' texture characteristic is impo... The gold concentration areas in the northwestern Jiaodong Peninsula constituted an important gold metallogenetic region in Eastern China during the Mesozoic. The deep geological bodies' texture characteristic is important for exploring the resources thoroughly and understanding the metallogenic process. The detailed textures were revealed using high-resolution seismic profiles through the three major ore-controlling structures-Sanshandao fault zone, Jiaojia fault zone and Zhaoping fault zone. This study aims to establish a deep structural framework of this area. Based on their formation mechanism, the fault structures developed in the area can be divided into regional and local fault structures. The structural styles are characterised by superimposing their compressional, strike-slip and extensional multi-stage activities. The crust is cut by vertical structures corresponding to a left-lateral strike-slip fault system on the surface. Nearby these structures are the arc-shape structures formed by multi-stage magma intrusions into the upper crust. Bounded by the Tancheng–Lujiang and Muping–Jimo fault zones, the current Jiaodong block, developed a series of NE-trending strike-slip fault systems, was probably formed by the assemblage of several obliquely aligned blocks. The intensive magmatism and hydrothermal activity between the blocks induced large-scale mineralisation. It provides a new angle of view for understanding the cratonic destruction and large ore-concentration formed during the Mesozoic. 展开更多
关键词 ore concentration area deep exploration strike-slip faults Sanshandao fault zone cratonic destruction Shandong
下载PDF
Protection and Construction Measures of Wild Animals' Habitats in Ecological Green Land Design in Town-and-City Concentration Areas of China
5
作者 凌静 吴迪 +2 位作者 辜彬 王思麒 罗言云 《Journal of Landscape Research》 2012年第5期61-64,共4页
Town-and-city concentration area is confronted with ecological degeneration due to the expansion of urbanization,and enriching urban bio-diversity is conducive to the improvement of ecological function of urban green ... Town-and-city concentration area is confronted with ecological degeneration due to the expansion of urbanization,and enriching urban bio-diversity is conducive to the improvement of ecological function of urban green system.The paper has studied how to increase urban bio-diversity by making use of urban green lands for protection and construction of wild animals' habitats,and proposed the significance and theoretical idea for protection and construction of wild animals' habitats.By taking ecological green lands design in Qinglongchang of Chengdu City for example,it has analyzed the current situation of animals' diversity;proposed to plan corridor,construct biological channel and provide multiporous habitats;listed plants' selection and collocation mode;and finally illustrated how to set artificial facilities for attraction of animals.It hopes to provide a reference for the design of ecological green lands in cities advocating the harmonious development of living environment and natural environment. 展开更多
关键词 Wild animals’ HABITATS ECOLOGICAL green lands Town-and-city concentration area
下载PDF
Metallogeny of the Baiyangping Lead-Zinc Polymetallic Ore Concentration Area, Northern Lanping Basin of Yunnan Province, China 被引量:5
6
作者 WANG Xiaohu SONG Yucai +3 位作者 ZHANG Hongrui LIU Yingchao PAN Xiaofei GUO Tao 《Acta Geologica Sinica(English Edition)》 CAS CSCD 2018年第4期1486-1507,共22页
The Lanping Basin in the Nujiang-Lancangjiang-Jinshajiang (the Sanjiang) area of northeastern margin of the Tibetan Plateau is an important part of eastern Tethyan metallogenic domain. This basin hosts a number of l... The Lanping Basin in the Nujiang-Lancangjiang-Jinshajiang (the Sanjiang) area of northeastern margin of the Tibetan Plateau is an important part of eastern Tethyan metallogenic domain. This basin hosts a number of large unique sediment-hosted Pb-Zn polymetallic deposits or ore districts, such as the Baiyangping ore concentration area which is one of the representative ore district. The Baiyangping ore concentration area can be divided into the east and west ore belts, which were formed in a folded tectogene of the India-Asia continental coUisional setting and was controlled by a large reverse fault. Field observations reveal that the Mesozoic and Cenozoic sedimentary strata were outcropped in the mining area, and that the orebodies are obviously controlled by faults and hosted in sandstone and carbonate rocks. However, the oreforming elements in the east ore belt are mainly Pb-Zn -Sr-Ag, while Pb-Zn-Ag-Cu-Co elements are dominant in the west ore belt. Comparative analysis of the C-O-Sr-S-Pb isotopic compositions suggest that both ore belts had a homogeneous carbon source, and the carbon in hydrothermal calcite is derived from the dissolution of carbonate rock strata; the ore- forming fluids were originated from formation water and precipitate water, which belonged to basin brine fluid system; sulfur was from organic thermal chemical sulfate reduction and biological sulfate reduction; the metal mineralization material was from sedimentary strata and basement, but the difference of the material source of the basement and the strata and the superimposed mineralization of the west ore belt resulted in the difference of metallogenic elements between the eastern and western metallogenic belts. The Pb-Zn mineralization age of both ore belts was contemporary and formed in the same metaliogenetic event. Both thrust formed at the same time and occurred at the Early Oligocene, which is consistent with the age constrained by field geological relationship. 展开更多
关键词 eastern Tethyan metallogenic domain Lanping Basin Baiyangping ore concentration area lead-zinc polymetallic ore deposit genesis of deposit
下载PDF
Carbon Dioxide Concentration and Flux in an Urban Residential Area in Seoul,Korea 被引量:2
7
作者 Moon-Soo PARK Seung Jin JOO Soon-Ung PARK 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2014年第5期1101-1112,共12页
The carbon dioxide (CO2) concentrations and fluxes measured at a height of 17.5 m above the ground by a sonic anemometer and an open-path gas analyzer at an urban residential site in Seoul, Korea from February 2011 ... The carbon dioxide (CO2) concentrations and fluxes measured at a height of 17.5 m above the ground by a sonic anemometer and an open-path gas analyzer at an urban residential site in Seoul, Korea from February 2011 to January 2012 were analyzed. The annual mean CO2 concentration was found to be 750 mg m-3, with a maximum monthly mean concentration of 827 mg m-3 in January and a minimum value of 679 mg m-3 in August. Meanwhile, the annual mean CO2 flux was found to be 0.45 mg m-2 s-1, with a maximum monthly mean flux of 0.91 mg m-2 s-1 in January and a minimum value of 0.19 mg m-2 s-1 in June. The hourly mean CO2 concentration was found to show a significant diurnal variation; a maximum at 0700-0900 LST and a minimum at 1400-1600 LST, with a large diurnal range in winter and a small one in summer, mainly caused by diurnal changes in mixing height, CO2 flux, and surface complexity. The hourly mean CO2 flux was also found to show a significant diurnal variation, but it showed two maxima at 0700-0900 LST and 2100-2400 LST, and two minima at 1100-1500 LST and 0300-0500 LST, mainly caused by a diurnal pattern in CO2 emissions and sinks from road traffic, domestic heating and cooking by liquefied natural gas use, and the different horizontal distribution of CO2 sources and sinks near the site. Differential advection with respect to wind direction was also found to be a cause of diurnal variations in both the CO2 concentration and flux. 展开更多
关键词 CO2 concentration CO2 flux liquefied natural gas (LNG) SEOUL urban residential area
下载PDF
DETERMINING THICKENER UNDERFLOW CONCENTRATION AND UNIT AREA 被引量:2
8
作者 Kang Yong Hu Xiaomin +1 位作者 Deng Changlie Luo Qian(Department of Mineral Engineering, Northeastern University, Shenyong 110006) 《中国有色金属学会会刊:英文版》 CSCD 1996年第3期29-35,共7页
DETERMININGTHICKENERUNDERFLOWCONCENTRATIONANDUNITAREA¥KangYong;HuXiaomin;DengChanglie;LuoQian(DepartmentofMi... DETERMININGTHICKENERUNDERFLOWCONCENTRATIONANDUNITAREA¥KangYong;HuXiaomin;DengChanglie;LuoQian(DepartmentofMineralEngineering,... 展开更多
关键词 BATCH SEDIMENTATION CURVE THICKENER UNIT area underflow concentration
下载PDF
Distribution of Surface Ozone Concentration in the Clean Areas of China and Its Possible Impact on Crop Yields 被引量:1
9
作者 李兴生 何耑士 +1 位作者 房秀梅 周秀骥 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1999年第1期156-160,共5页
From August 1994 to July 1995, ozone and its precursors were measured in the clean areas of China. The results show that in the period of crop growth, hourly mean ozone concentration, ozone concentration averaged in s... From August 1994 to July 1995, ozone and its precursors were measured in the clean areas of China. The results show that in the period of crop growth, hourly mean ozone concentration, ozone concentration averaged in seven hours of daytime and accumulated ozone concentration in long period have approached or overpassed the harmful level in environmental and health standard of U. S. A. and Canada. 展开更多
关键词 Clean area Surface ozone concentration Crop yield
下载PDF
Method of calculation of a methane concentration field in gob areas with a known velocity field based on the model of stream tubes 被引量:2
10
作者 Wang Honggang Wu Fengliang 《Mining Science and Technology》 EI CAS 2011年第2期277-280,共4页
The control equations of gas concentration field in gob areas with a known velocity field are partial differential equations with variable coefficients,whose traditional mathematical calculation methods are very compl... The control equations of gas concentration field in gob areas with a known velocity field are partial differential equations with variable coefficients,whose traditional mathematical calculation methods are very complex.A numerical simulation method can be used to calculate the gas concentration field,but it also needs considerable amounts of computer resources and the relations of gas concentration at different points of the gob area are undefined.Based on the model of stream tubes,the conservation equations of mass and gas components within the stream tube are used to deduce the equations of a gas concentration field in a gob area with a known velocity field.This method of calculation of a gas concentration field is applied in a gob area with a U-type ventilation working face,which suggests that this new method has the virtue of exact calculations is simple to operate and has a clear physical interpretation. 展开更多
关键词 Fluid field Cob area concentration field Stream tube
下载PDF
Magmatic Evolution and Mineralization of Porphyry Copper-Gold Deposits in the Duolong Ore Concentration Area, Tibet 被引量:1
11
作者 ZHANG Hai MA Dongfang +1 位作者 ZHANG Hong ZHU Xiangping 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2015年第5期1767-1768,共2页
The Bangong Lake-Nujiang River metallogenic belt is located between the Qiangtang Block and Lhasa Block, and the Duolong ore concentration area is located in the western section of the Bangong Lake-Nujiang River metal... The Bangong Lake-Nujiang River metallogenic belt is located between the Qiangtang Block and Lhasa Block, and the Duolong ore concentration area is located in the western section of the Bangong Lake-Nujiang River metallogenic belt. Till now, several large and super large copper-gold deposits, such as Duobuza, Bolong, Dibaonamugang, Naruo and Rongna deposits have been discovered in this area, mainly porphyry copper-gold ones. 展开更多
关键词 area LAKE Magmatic Evolution and Mineralization of Porphyry Copper-Gold Deposits in the Duolong Ore concentration area TIBET
下载PDF
A New Potential Caledonian–Indosinian Ore Concentration Area:Evidence from Diagenesis and Mineralization Ages of the Miao'ershan–Yuechengling Region 被引量:3
12
作者 ZHANG Wenlan CHE Xudong +2 位作者 CHEN Wendi WANG Rucheng ZHANG Di 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第2期743-744,共2页
Objective The Miao'ershan-Yuechengling composite granite, located in northern Guangxi at the western section of the Nanling Range, is a multi-period and multi-stage composite pluton with an exposed area of more than... Objective The Miao'ershan-Yuechengling composite granite, located in northern Guangxi at the western section of the Nanling Range, is a multi-period and multi-stage composite pluton with an exposed area of more than 3000 km2 (Fig. 1). Paleozoic and Proterozoic strata are exposed around it, and magmatic activities mainly occurred during the Caledonian and Indosinian periods. Till now, more than one hundred W-Sn-Mo-Pb-Zn-Cu (U) deposits and ore occurrences have been discovered along the inner and outer contact zones of this granite. Through recent years' research, we infer that this area is not only a preferred area for studying granite and mineralization in Caledonian and lndosinian periods, but also a potential Caledonian- lndosinian ore-concentrated area. 展开更多
关键词 Yuechengling Region Indosinian Ore concentration area:Evidence from Diagenesis and Mineralization Ages of the Miao’ershan A New Potential Caledonian
下载PDF
Factors Controlling Low Uranium and Thorium Concentrations in the Cayirhan Bituminous Shales(CBS)in the Beypazari(Ankara)Area,Turkey 被引量:1
13
作者 Berna Yavuz PEHLIVANLI Sükrü KOC +1 位作者 Ali SARI Hilal ENGIN 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2014年第1期248-252,I0009,I0010,253-259,共14页
In this study uranium and thorium contents and depositional characteristics of ay rhan bituminous shales( BS), west of Ankara(central Anatolia), are investigated. Samples used were collected from boreholes opened ... In this study uranium and thorium contents and depositional characteristics of ay rhan bituminous shales( BS), west of Ankara(central Anatolia), are investigated. Samples used were collected from boreholes opened by Park Holding Ltd. A total of 25 samples were taken from bituminous shale levels in boreholes drilled at 6 different locations in the study area. The H rka formation which hosts bituminous shale deposits is a volcanosedimentary sequence and all lithofacies indicate that a lacustrine environment where the water level was continuously changed. In addition to hydrocarbon generation potential, bituminous shales also accumulate significant amount of radioactive elements such as uranium and thorium. The average uranium and thorium concentrations of BS(1.83/2.62 ppm) are much lower than averages of UC, NASK and PAAS(uranium: 2.70/2.66/3.10 ppm; thorium: 8.50/12.30/14.60 ppm). Low uranium contents in comparison to those of similar lacustrine environments might be attributed to that waters of depositional environment of BS contain low concentration of dissolved uranium and redox conditions were of oxic and dioxic character. Correlation data indicate that U and Th have a similar source and are associated predominantly with clays and phosphates and dominantly with organic material. Radioactive elements in the basin might be derived from Paleozoic granites and metamorphites(e.g. gneiss, schist) which comprise the basement and volcanism which was active in the region throughout the Miocene period. These elements are probably associated with uraniferous phosphate minerals(e.g. autunite, torbernite) which occur in granite, gneiss and schist. BS with average TOC content of 10.96 % shows very good/perfect source rock potential. Positive correlations between Gamma-Ray values and U, Th and K concentrations imply that radioactivity might be originated from these three elements. 展开更多
关键词 Uranium and Thorium concentrations ay rhan bituminous shales Beypazar area TURKEY
下载PDF
The Study of Area-Concentration Fractal Method in Litho-Geochemical Data in Tanurjeh Area, Khorasan Province
14
作者 Kimya Ajayebi Hamidreza Jafari Behzad Behbahani 《Open Journal of Geology》 2015年第6期451-457,共7页
Given the scientific progresses as well as the invention of new methods in exploration, it is necessary to conduct some re-investigations in several exploration zones. So, in the present research, geochemical data on ... Given the scientific progresses as well as the invention of new methods in exploration, it is necessary to conduct some re-investigations in several exploration zones. So, in the present research, geochemical data on Tanurjeh exploration zone, (located in Northern Neishaboor, Khorasane Razavi province) is studied by using some modern statistical methods. Fractal methods are appropriated to study and separate the grades societies in deposits. In this article, litho-geochemical analysis results (ICP) are processed by concentration area fractal method (CA). The distribution diagrams related to the statistical populations are drawn, and anomaly populations of Copper, Gold and Molybdenum are determined besides previous studies (petrography and alteration), the results of statistic methods (CA) and aid presence of the porphyry system in depth. 展开更多
关键词 concentration FRACTAL Method Litho-Geochemical Data Tanurjeh area
下载PDF
Effects of leaf N concentration and leaf area index on determining rice tillering
15
《Chinese Rice Research Newsletter》 1999年第4期8-9,共2页
Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tille... Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tilleringamong a wide range of N application,field ex- periments were conducted at the IRRI farm,Los Banos,Laguna,the Philippines.Two in- dica cultivars,IR 72 and IR68284H wereused.For each cultivar,12 treatments includ- ing 4 N levels(0,60,120,and 180kgN·ha)and 3 transplanting spacing(30×20,20×20,and 10×20cm)were arranged in a ran-domized split-plot design with 4 replications.The N treatments were designated as mainplots and spacings as subplots.Fourteen-day-old seedlings were transplanted with 3seedlings per hill.The subplot area was 20m~2.Nitrogen fertilizer was applied as basal,atmidtillering,and at panicle initiation in threeequal splits.P,K,and Zn were applied asbasal at normal dosage.The field was flooded.Plant samples were taken every 7-14 d from 14d after transplanting to flower 展开更多
关键词 area IR Effects of leaf N concentration and leaf area index on determining rice tillering
下载PDF
Creep properties and resistivity-ultrasonic-AE responses of cemented gangue backfill column under high-stress area 被引量:11
16
作者 Hongyu Ran Yuxia Guo +2 位作者 Guorui Feng Tingye Qi Xianjie Du 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2021年第3期401-412,共12页
To investigate the creep and instability properties of a cemented gangue backfill column under a highstress area,the uniaxial compression creep tests were conducted by single-step and multi-step loading of prismatic s... To investigate the creep and instability properties of a cemented gangue backfill column under a highstress area,the uniaxial compression creep tests were conducted by single-step and multi-step loading of prismatic samples made of cemented gangue backfill material(CGBM)under the high stressstrength ratio.The creep damage was monitored using an electrical resistivity device,ultrasonic testing device,and acoustic emission(AE)instrument.The results showed that the CGBM sample has a creep hardening property.The creep failure strength(CFS)is slightly larger than the uniaxial compressive strength(UCS),ranging in ratio from 108.9%to 116.5%.The instantaneous strain,creep strain,and creep rate increase with increasing stress-strength ratio in the single-step loading creep tests.The instantaneous strain and creep strain decrease first and then increase during the multi-step loading creep process.The axial creep strain of the CGBM column can be expressed by the viscoelastic-plastic creep model.Creep instability is caused by the accumulation of strain energy under multi-step loading and the continuous lateral expansion at the unconstrained middle position during the creep process.The creep stability of a CGBM column in a high-stress area can be monitored based on the variation of electrical resistivity,ultrasonic pulse velocity(UPV),and AE signals. 展开更多
关键词 Cemented gangue backfill column Creep and instability properties high-stress area Electrical resistivity Ultrasonic pulse velocity Acoustic emission
下载PDF
STRATEGY OF MAIZE′S CONCENTRATING TO ADVANTAGE AREAS IN JILIN PROVINCE 被引量:2
17
作者 JIANG Hui-ming,GU Li-li(Managerial College,Jilin Agricultural University,Changchun 130118,P. R. China) 《Chinese Geographical Science》 SCIE CSCD 2003年第4期378-382,共5页
Jilin Province is one of the main grain-producing provinces of China,which has dominant position in maize production,by the view of its advantages in policy,location,breed and market. And after entering WTO,some measu... Jilin Province is one of the main grain-producing provinces of China,which has dominant position in maize production,by the view of its advantages in policy,location,breed and market. And after entering WTO,some measures have been taken to enhance maize competitive ability. But there are some difficulties in concentrating production to maize advantaged areas. This paper expounds the basis that Jilin Province becomes the advantage area of maize,analyzes the problems and puts forward the supporting policy. Some strategic measures are proposed,as developing comparable advantages,carrying out the strategy of un-equilibrium development and cultivating advantaged product areas of maize to rapidly improve the international competitive ability and productivity of maize in Jilin Province,cast the agricultural predicament off and promote the agricultural development into a new stage. 展开更多
关键词 MAIZE advantage area concentration Jilin province
下载PDF
Geological Characteristics of Epithermal Ore Concentrated Areas and Epithermal Ore Deposits in China
18
作者 Li Chaoyang Pan Jiayong Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 《Journal of Earth Science》 SCIE CAS CSCD 1999年第1期47-50,共4页
The epithermal ore concentrated area is located in Southwestern China. We systematically study the regional geological characteristics such as the basement of Proterozoic, the capping bed, Moho, geothermal feature and... The epithermal ore concentrated area is located in Southwestern China. We systematically study the regional geological characteristics such as the basement of Proterozoic, the capping bed, Moho, geothermal feature and tectonics, and discuss the relationship between distributed characteristics of the epithermal ore deposits and ore control factors in this paper. It is concluded that the conditions, under which the epithermal ore deposits form, are huge thick basement of Proterozoic, long time and wide scope developed capping bed and weak magmatic activity. The basement of Proterozoic that enriches volcanic matters and carbon and the carbonaceous bearing and paleo pool bearing capping bed provides main ore source. The large and deep faults and paleopool accordance with gravity anomaly gradient control the distribution of epithermal ore deposits. The lithologic assembles of microclastic rocks and carbonate rocks in the capping bed provide spaces of ore precipitation and create conditions of ore precipitation. The coincidence of many geological factors above forms the epithermal ore concentrated area. 展开更多
关键词 epithermal ore deposits epithermal ore concentrated areas geological setting Southwestern China.
下载PDF
^(40)Ar-^(39)Ar Dating of Quartz from Ore in the Baiyangping Cu-Co Polymetallic Ore-Concentrated Area, Lanping Basin, Yunnan
19
作者 何明勤 刘家军 +4 位作者 李朝阳 李志明 刘玉平 杨爱平 桑海清 《Chinese Journal Of Geochemistry》 EI CAS 2004年第4期342-348,共7页
Ar- 39Ar fast neutron activation age spectrum of quartz in ore collected from the Baiyangping Cu-Co polymetallic ore-concentrated area, Lanping Basin, is saddle-shaped. The plateau age, minimum appearance age and isoc... Ar- 39Ar fast neutron activation age spectrum of quartz in ore collected from the Baiyangping Cu-Co polymetallic ore-concentrated area, Lanping Basin, is saddle-shaped. The plateau age, minimum appearance age and isochron age shown on the spectra are 56.53± 0.43 Ma, 55.52± 1.78 Ma and 55.90± 0.29 Ma respectively. The age data are consistent with each other within 1σ uncertainties. Because the given initial 40Ar/ 36Ar value of 294.7± 1.14 is very close to Nier’s value ( 295.5±5), both plateau and isochron ages may be considered as the forming time of quartz. So the age of 55.90- 56.53 Ma represents the forming age of ore deposits. It is obvious that the ore deposits were formed during the Early Himalayan period. 展开更多
关键词 年龄测定 喜玛拉雅早期运动 铜-钴多金属矿集中地区 云南西部
下载PDF
比较浓度-时间曲线下面积与谷浓度指导万古霉素治疗重症患者的临床随机对照研究
20
作者 王锐 何囡囡 +4 位作者 席振创 罗延年 高雪花 李美玲 曹雯 《中国急救医学》 CAS CSCD 2024年第11期996-1001,共6页
目的探讨浓度-时间曲线下面积和谷浓度指导万古霉素治疗重症患者的临床安全性和疗效差异。方法入选2021年1月至2023年12月收住兰州大学第二医院重症医学科因革兰阳性菌感染且经医师确认需使用万古霉素治疗的患者,经纳排标准筛选后,采用... 目的探讨浓度-时间曲线下面积和谷浓度指导万古霉素治疗重症患者的临床安全性和疗效差异。方法入选2021年1月至2023年12月收住兰州大学第二医院重症医学科因革兰阳性菌感染且经医师确认需使用万古霉素治疗的患者,经纳排标准筛选后,采用随机数字表法将入选患者分为两组进行前瞻性、随机、单盲对照研究,对照组以万古霉素谷浓度10~20 mg/L为目标靶值,观察组以万古霉素浓度-时间曲线下面积400~600 mg·h/L为目标靶值。经过监测,最终对照组77例、观察组79例符合目标靶值范围并进行相关统计学分析与比较。结果观察组万古霉素相关急性肾损伤(AKI)发生率明显低于对照组(P=0.002),两组临床疗效及总治疗时间差异无统计学意义。根据多因素Logistic回归分析显示,谷浓度(OR=1.021,95%CI 1.019~1.577,P=0.033)及急性生理学和慢性健康状况评价Ⅱ(APACHEⅡ)评分(OR=1.189,95%CI 1.055~1.339,P=0.004)是万古霉素相关AKI独立危险因素,采样总数量(OR=0.476,95%CI 0.247~0.917,P=0.000)是临床转归独立危险因素。对谷浓度与万古霉素相关AKI进行受试者工作特征(ROC)曲线分析,谷浓度预测万古霉素相关AKI临界值为15.65 mg/L,敏感度为0.786,特异度为0.697,ROC曲线下面积为0.727。结论基于浓度-时间曲线下面积为目标靶值的药物监测方法,可以减少万古霉素相关AKI发生,但临床疗效无差别。 展开更多
关键词 浓度-时间曲线下面积 谷浓度 万古霉素 肾毒性
下载PDF
上一页 1 2 86 下一页 到第
使用帮助 返回顶部