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Are the altitudinal patterns of plant diversity derived from field surveys consistent with those from empirical integrated methods?
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作者 ZHAN Qing-hua FU Zhi-hao +2 位作者 ZHOU Ya-dong YAN Xue WANG Qing-feng 《Journal of Mountain Science》 SCIE CSCD 2023年第5期1307-1315,共9页
Field surveys and empirical integrated methods are commonly used in the ecological research to understand the altitudinal pattern of plant diversity of mountains.However,few studies have compared the differences betwe... Field surveys and empirical integrated methods are commonly used in the ecological research to understand the altitudinal pattern of plant diversity of mountains.However,few studies have compared the differences between the two methods on the same scale.Here,we addressed and compared the altitudinal patterns of species richness(SR),phylogenetic diversity(PD),the standardized effect size of phylogenetic diversity(PDses)and mean phylogenetic distance(MPDses)of about 580 angiosperms growing on Mount Kenya from two independent datasets:one is based on our several times field surveys in this mountain and another one is based on empirical data integrated from literatures.We found that the altitudinal diversity patterns of field surveys dataset were consistent with the empirical integrated dataset.Both SR and PD showed hump-shaped patterns along the altitude,and both PDses and MPDses showed monotonically decreasing patterns along the altitude.The ratio of diversity between field surveys dataset and empirical integrated dataset were gradually increase along the altitude.Our research provides new insight for understanding the altitudinal diversity patterns of plants of a tropical mountain. 展开更多
关键词 Mount Kenya AFRICA surveys Interpolation method TAXONOMIC PHYLOGENETIC
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Insync Surveys图书馆用户满意度调查分析 被引量:8
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作者 张为杰 杨广锋 周婕 《图书情报知识》 CSSCI 北大核心 2009年第6期34-38,86,共6页
Insync Surveys,原名Ambit Insights/Rodski Survey Research,是澳大利亚一家调查服务公司。其用户满意度调查自1998年在墨尔本大学图书馆实施以来,影响不断扩大,并与CAUL建立了稳定的合作关系。Insync Surveys以关注度-满意度为方法基... Insync Surveys,原名Ambit Insights/Rodski Survey Research,是澳大利亚一家调查服务公司。其用户满意度调查自1998年在墨尔本大学图书馆实施以来,影响不断扩大,并与CAUL建立了稳定的合作关系。Insync Surveys以关注度-满意度为方法基础,指标体系灵活调整,并提供基本调查和全面调查两种服务模式,取得了良好的实践效果。 展开更多
关键词 Insync surveys Rodski 满意度调查 服务质量评估
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Analysis of the Results of Two Nationwide Surveys on Clonorchis sinensis Infection in China 被引量:22
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作者 CHEN Ying Dan ZHOU Chang Hai XU Long Qi 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2012年第2期163-166,共4页
Objective To examine Clonorchis sinensis infection in China and evaluate the effectiveness of efforts to prevent and control it,two nationwide surveys were undertaken in 31 provinces,autonomous regions,and municipalit... Objective To examine Clonorchis sinensis infection in China and evaluate the effectiveness of efforts to prevent and control it,two nationwide surveys were undertaken in 31 provinces,autonomous regions,and municipalities(PAMs) during 1988-92(the 1990 survey) and during 2001-04(the 2003 survey).Methods During the period 2001-04,two sampling methods were applied.The first method repeated the stratified cluster random sampling used in the 1990 survey;the second method applied two-characteristic stratified cluster random sampling in 27 PAMs—the 2003 endemic area(EA) survey.The Kato-Katz thick smear method was used for the nationwide survey.Results The infection rates of Clonorchis sinensis in the 1990 and 2003 surveys were 0.311% and 0.579%,respectively.The infection rate was 2.40% in the 2003 EA survey,and it was estimated that 12.49 million people in China were infected with Clonorchis sinensis.Conclusion The 2003 survey showed that the standardized infection rate of Clonorchis sinensis increased by 74.85% compared with the 1990 survey.The infection rate in males was higher than in females;the infection rate among people eating raw fish or eating out frequently was higher than among those who did not. 展开更多
关键词 Clonorchis sinensis Two nationwide surveys The status of infection in China
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Taxonomy is the cornerstone of biodiversity conservation SEABRI reports on biological surveys in Southeast Asia 被引量:3
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作者 Shu-Qiang Li Rui-Chang Quan 《Zoological Research》 CAS CSCD 2017年第5期213-213,共1页
The Southeast Asia Biodiversity Research Institute (SEABRI) is an international scientific research and education organization affiliated directly to the Chinese Academy of Sciences (CAS) and managed by the Xishua... The Southeast Asia Biodiversity Research Institute (SEABRI) is an international scientific research and education organization affiliated directly to the Chinese Academy of Sciences (CAS) and managed by the Xishuangbanna Tropical Botanical Garden (XTBG). By harnessing its connections with all CAS institutes, local institutes and international agencies and leveraging on their resources, it seeks to make a significant contribution to biodiversity conservation in Southeast Asia. 展开更多
关键词 In SEABRI reports on biological surveys in Southeast Asia Taxonomy is the cornerstone of biodiversity conservation
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Research Surveys of Electrochemical Sensors for in-situ Determining Hydrogen in Steels 被引量:1
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作者 Gang YU, Xueyuan ZHANG and Yuanlong DU (State Key Laboratory for Corrosion and Protection, Institute of Corrosion and Protection of Metals, Chinese Academy of Sciences, Shenyang 110015, China) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2000年第3期305-310,共6页
The principle, construction and application of two types of electrochemical sensors-amperometric and potentiometric are surveyed. Both types of sensors are very sensitive to changes in temperature. The accuracy of hyd... The principle, construction and application of two types of electrochemical sensors-amperometric and potentiometric are surveyed. Both types of sensors are very sensitive to changes in temperature. The accuracy of hydrogen measurement depends on both the precision of sensors developed and the reliable technique of installation and security of sensors. The two types of sensors have been used for in-situ determining hydrogen permeated in steels owing to a corrosive reaction, a hydrogen gas circumstance at elevated temperatures and high pressure or also a pretreatment process such as pickling and plating process, etc. 展开更多
关键词 Research surveys of Electrochemical Sensors for in-situ Determining Hydrogen in Steels NIO
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Integrated geophysical surveys on railroads in permafrost areas
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作者 A.Ivanov S.Klepikova +2 位作者 M.Shirobokov A.Urusova A.Savin 《Research in Cold and Arid Regions》 CSCD 2013年第5期582-586,共5页
The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engineer-geologist s... The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engineer-geologist survey been held in railway industry. This paper presents general issues concerning railway construction and operation in permafrost areas. Comprehensive geophysical methods to monitor the development of thawed soils axe considered in detail. The main physical parameters which help define permafrost and thawed soil patches are described. Author of current paper pointed out main factors, allowing predicting potential areas of development of thawed grounds. They offered set non-destructive methods: GPR investigations, seismic survey and elec- tric exploration. Whole sets of geophysical data: electric resistivity, velocity of S-wave and P-wave (and their correlation), allow us with high confidence specify characteristics and state of soil either under the line of road, or near it. At the same time the meth- od allows to predict direction of further development of thawed ground area. 展开更多
关键词 geophysical surveys on railroads ground-penetrating radar geoelectric sounding seismic refraction survey perma- frost thawed soils
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Color-Redshift Relations and Photometric Redshift Estimations of Quasars in Large Sky Surveys
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作者 Xue-BingWu WeiZhang XuZhou 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2004年第1期17-27,共11页
With a recently constructed composite quasar spectrum and the χ<SUP>2</SUP> minimization technique, we describe a general method for estimating the photometric redshifts of a large sample of quasars by de... With a recently constructed composite quasar spectrum and the χ<SUP>2</SUP> minimization technique, we describe a general method for estimating the photometric redshifts of a large sample of quasars by deriving theoretical color-redshift relations and comparing the theoretical colors with the observed ones. We estimated the photometric redshifts from the 5-band SDSS photometric data of 18678 quasars in the first major data release of SDSS and compared them with their spectroscopic redshifts. The difference is less than 0.1 for 47 % of the quasars and less than 0.2 for 68 %. Based on the calculation of the theoretical color-color diagrams of stars, galaxies and quasars both on the SDSS system and on the BATC system, we expect that we would be able to select candidates of high redshift quasars more efficaciously with the latter than with the former, provided the BATC survey can detect objects with magnitudes fainter than 21. 展开更多
关键词 galaxies: photometry quasars: general quasars: emission lines surveys
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Toward Estimating the Variance in Acoustic Surveys Based on Sampling Design
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作者 Magnar Aksland 《Open Journal of Marine Science》 2011年第1期1-17,共17页
This paper develops a sampling method to estimate the integral of a function of the area with a strategy to cover the area with parallel lines of observation. This sampling strategy is special in that lines very close... This paper develops a sampling method to estimate the integral of a function of the area with a strategy to cover the area with parallel lines of observation. This sampling strategy is special in that lines very close to each other are selected much more seldom than under a uniformly random design for the positions of the parallel lines. It is also special in that the positions of some of the lines are deterministic. Two different variance estimators are derived and investigated by sampling different man made signal functions. They show different properties in that the estimator that estimate the biggest variance gives an error interval that, in some situations, may be more than ten times the error interval computed from the other estimator. It is also obvious that the second estimator underestimates the variance. The author has not succeeded to derive an expression for the expectation of this estimator. This work is motivated towards finding the variance of acoustic abundance estimates. 展开更多
关键词 ACOUSTIC ABUNDANCE ESTIMATION LINE surveys Sampling Design Sampling in the Area Variance ESTIMATION
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Vocal behavior of Crested Guineafowl(Guttera edouardi) based on visual and sound playback surveys in the Umhlanga Lagoon Nature Reserve,Kwa Zulu-Natal province,South Africa
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作者 Johann H.van Niekerk 《Chinese Birds》 CSCD 2015年第3期132-139,共8页
Background:Generally speaking,playbacks were often ineffective to determine the group sizes of birds since mainly males from leks responded.This limitation has not been tested properly for flocking birds such as Crest... Background:Generally speaking,playbacks were often ineffective to determine the group sizes of birds since mainly males from leks responded.This limitation has not been tested properly for flocking birds such as Crested Guineafowl(Guttera edouardi) with the view to use it as a counting method.The aims of the study reported in this paper were(1) to describe the cal s of Crested Guineafowl in a social context;(2) to interpret cal s in an evolutionary context;and(3) to demonstrate that playbacks can be used to locate and count Crested Guineafowl in smal isolated forests.Methods:The vocal behavior of Crested Guineafowl was observed during a survey conducted in the Umhlanga Lagoon Nature Reserve(Kwa Zulu-Natal,South Africa) from November 2010 to June 2012.Transect line observations and sound playback methods were used.Results:The behavioral context and structure of cal s were described.The eight cal s described for Crested Guineafowl were produced mainly to unite flock members in the dense understory,where visibility was poor,and to repel intruders.When not disturbed,Crested Guineafowl were quiet and only made soft contact calls.Conclusions:The high rate of call back and the fact that flocks invariably approach the source of the call en masse,shows that field researchers are able to assess the population size of Crested Guineafowl with sound playbacks along a transect.The value of playbacks as a conservation tool is assessed. 展开更多
关键词 Guttera edouardi PLAYBACK CALLS Social behavior FLOCKING TRANSECT surveys
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Discussions about Magic Weapon of CPC's Work Based on Study of Mao Zedong's Rural Surveys
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作者 Xiaoting MENG Peng YANG 《Asian Agricultural Research》 2018年第4期103-106,共4页
Former chairman Mao Zedong conducted extensive rural surveys during the exploration of the Chinese revolutionary road. In 1941,in order to change the state of the party's theory separating from reality,Mao Zedong ... Former chairman Mao Zedong conducted extensive rural surveys during the exploration of the Chinese revolutionary road. In 1941,in order to change the state of the party's theory separating from reality,Mao Zedong organized and published the book Rural Surveys,which provided the direction for survey and research of the party members. The survey and research are excellent tradition and style of work of the party,and also a major weapon for outstanding achievements in China's revolution and construction. Socialism with Chinese characteristics has entered a new era. Studying the Rural Surveys has important practical value for beating off the new challenges in the issues concerning agriculture,farmers,and rural areas. 展开更多
关键词 SURVEY Mao Zedong Rural surveys Magic weapon
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Shallow Reflection Surveys of the East Ongul Island, the Lützow-Holm Complex, East Antarctica
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作者 Masaki Kanao Tetsuya Takemoto +2 位作者 Akira Fujiwara Kiyoshi Ito Takeshi Ikawa 《International Journal of Geosciences》 2014年第9期1037-1047,共11页
The shallow reflection surveys were carried out in 2007 and 2010 austral summers in East Ongul Island, the Lützow-Holm Complex (LHC), East Antarctica. LHC is identified by geologically as one of the Pan-African t... The shallow reflection surveys were carried out in 2007 and 2010 austral summers in East Ongul Island, the Lützow-Holm Complex (LHC), East Antarctica. LHC is identified by geologically as one of the Pan-African terrains of Eastern Dronning Maud Land. The multi-channel reflection surveys targeted to achieve the image of laminated layering of metamorphic rocks near the surface (the depths down to a few hundreds of meters) of the crystalline crust. Two surveys were conducted in total length of the profiles about 500 m along a main traffic load across the East Ongul Island. The multi-channel acquisition systems were utilized with combining the dense geophones along the profiles. Seismic sources were adopted by combining the boom of a power shovel, a weight drop and hammer shots with their intervals in a few tens of meters. The obtained data include clear first P-arrivals in far offset distance. The energy of P-S converted waves was enhanced because of the characteristics of the seismic sources. Pre-stacked images could be expected to the information on metamorphic layering for several lithological structure composed by hornblende gneiss, garnet gneiss and pyroxene gneiss appearing as the surface bedrocks. The conducted shallow reflection surveys would give rise to one step for understanding tectonic formation of LHC, as one of the Pan-African mobile belts in Gondwana super-continent. 展开更多
关键词 SHALLOW REFLECTION surveys METAMORPHIC LAYERING CRUSTAL Structure Continental Evolution East ANTARCTICA
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The Use of Spatial Sampling Designs in Business Surveys
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作者 Maria Michela Dickson Roberto Benedetti +1 位作者 Diego Giuliani Giuseppe Espa 《Open Journal of Statistics》 2014年第5期345-354,共10页
An innovative use of spatial sampling designs is here presented. Sampling methods which consider spatial locations of statistical units are already used in agricultural and environmental contexts, while they have neve... An innovative use of spatial sampling designs is here presented. Sampling methods which consider spatial locations of statistical units are already used in agricultural and environmental contexts, while they have never been exploited for establishment surveys. However, the rapidly increasing availability of geo- referenced information about business units makes that possible. In business studies, it may indeed be important to take into account the presence of spatial autocorrelation or spatial trends in the variables of interest, in order to have more precise and efficient estimates. The opportunity of using the most innovative spatial sampling designs in business surveys, in order to produce samples that are well spread in space, is here tested by means of Monte Carlo experiments. For all designs, the Horvitz-Thompson estimator of the population total is used both with equal and unequal inclusion probabilities. The efficiency of sampling designs is evaluated in terms of relative RMSE and efficiency gain compared with designs ignoring the spatial information. Furthermore, an evaluation of spatially balancing samples is also conducted. 展开更多
关键词 SPATIAL Sampling DESIGN BUSINESS surveys Horvitz-Thompson ESTIMATOR SPATIAL BALANCE
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Chen Yun's Rural Surveys in China
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作者 Yurong QUAN Peng YANG 《Asian Agricultural Research》 2022年第2期17-22,共6页
In order to explore a way to completely transform China,the Chinese Communists have vigorously promoted the style of investigations and research in rural areas.Chen Yun is a model of this rural investigation movement.... In order to explore a way to completely transform China,the Chinese Communists have vigorously promoted the style of investigations and research in rural areas.Chen Yun is a model of this rural investigation movement.He focused on understanding the life of the peasant class and the reality of China's rural areas through field investigations.The survey content was meticulous and extensive,and the survey process sought truth from facts.He creatively used a variety of survey methods based on objective conditions,and strove to earnestly benefit the people.Chen Yun provided Marxist guiding ideology for rural investigations in China,guided rural investigations to proceed on the right track,and at the same time infused rural investigations with the value concept of putting the people first,which still has important reference significance for solving the problems of agriculture,rural areas and farmers in the new situation. 展开更多
关键词 Chen Yun Rural surveys Seeking truth from facts
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Fuzzy Geometric Programming in Multivariate Stratified Sample Surveys in Presence of Non-Response with Quadratic Cost Function
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作者 Shafiullah   Mohammad Faisal Khan Irfan Ali 《American Journal of Operations Research》 2014年第3期173-188,共16页
In this paper, the problem of non-response with significant travel costs in multivariate stratified sample surveys has been formulated of as a Multi-Objective Geometric Programming Problem (MOGPP). The fuzzy programmi... In this paper, the problem of non-response with significant travel costs in multivariate stratified sample surveys has been formulated of as a Multi-Objective Geometric Programming Problem (MOGPP). The fuzzy programming approach has been described for solving the formulated MOGPP. The formulated MOGPP has been solved with the help of LINGO Software and the dual solution is obtained. The optimum allocations of sample sizes of respondents and non respondents are obtained with the help of dual solutions and primal-dual relationship theorem. A numerical example is given to illustrate the procedure. 展开更多
关键词 Geometric PROGRAMMING FUZZY PROGRAMMING NON-RESPONSE with Travel Cost Optimum ALLOCATIONS MULTIVARIATE STRATIFIED Sample surveys
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Wide-bandwidth drift-scan pulsar surveys of globular clusters:application to early science observations with FAST
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作者 Lei Zhang George Hobbs +7 位作者 Di Li Duncan Lorimer Jie Zhang Meng Yu You-Ling Yue Pei Wang Zhi-Chen Pan Shi Dai 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2016年第10期11-20,共10页
The Five-hundred-meter Aperture Spherical Telescope (FAST) will begin its early-science oper- ations during 2016. Drift-scan pulsar surveys will be carried out during this period using an ultra-wide-band receiver sy... The Five-hundred-meter Aperture Spherical Telescope (FAST) will begin its early-science oper- ations during 2016. Drift-scan pulsar surveys will be carried out during this period using an ultra-wide-band receiver system (covering - 270 to 1620 MHz). We describe a method for accounting for the changes in the telescope beam shape and the pulsar parameters when searching for pulsars over such a wide bandwidth. We applied this method to simulated data sets of pulsars in globular clusters that are visible to FAST and found that a representative observation would have a sensitivity of -40 ply. Our results showed that a sin- gle drift-scan (lasting less than a minute) is likely to find at least one pulsar for observations of four globular clusters. Repeated observations will increase the likely number of detections. We found that pulsars in - 16 clusters are likely to be found if the data from 100 drift-scan observations of each cluster are incoherently combined. 展开更多
关键词 pulsars -- drift-scan pulsar surveys -- globular clusters
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Sanitary Surveys and Hydrochemistry of Groundwater in Two Urban Towns (Ado-Ekiti and Ijero-Ekiti), Southwestern Nigeria
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作者 Abel Ojo Talabi Lekan Olatayo Afolagboye +1 位作者 Christopher Ayodele Ajayi Olufunke Kolawole 《Journal of Geoscience and Environment Protection》 2022年第7期159-185,共27页
Groundwater contamination in urban cities is imminent in the phase of increased anthropogenic activities apart from the contribution of geogenic contaminants. This study examined the sanitary surveys and hydrochemistr... Groundwater contamination in urban cities is imminent in the phase of increased anthropogenic activities apart from the contribution of geogenic contaminants. This study examined the sanitary surveys and hydrochemistry of groundwater in Ado-Ekiti and Ijero-Ekiti to establish the contaminants’ sources, decipher the effects of urbanization on population and explain any relationship between the surveys and the groundwater chemistry. Sanitary surveys of 30 randomly selected wells each from Ado-Ekiti and Ijero-Ekiti were executed by administering and processing appropriately designed questionnaires that addressed salient problems of hygiene and sanitation. The results of the surveys were grouped into very high risk, high risk, intermediate risk, and low risk classes. Subsequently, at each location, in situ parameters (temperature (°C), pH and EC (μS/cm)) were measured using a portable Multi-parameter TestrTM 35 Series S/N: 1382654. At each well, water samples were collected into clean polyethylene bottles in triplicates for cation, anions and e-coli evaluations, respectively. Water samples for cations were acidified by adding two drops of concentrated nitric acid. All samples were kept in a refrigerator at a low temperature of about 4°C before being taken to the Federal University of Technology, Akure, for analyses. Ion chromatography was employed for the anions analysis while the cations were determined using an Atomic Absorption Spectrophotometer Buck 210 model. Membrane filter technique was employed for the e-coli estimation. From the results of the hydrochemistry, the Nitrate Pollution Index (NPI) and Modified Nitrate Pollution Index (MNPI) were estimated and classified into;clean unpolluted, light pollution, moderate pollution, significant pollution, very significant pollution waters. Sanitary surveys in the two cities showed that in the very low risk, intermediate and high-risk categories, Ado-Ekiti had 33.33%, 56.67% and 10% representations, while Ijero-Ekiti had 50%, 23.33% and 26.67% representations, respectively. This observation showed that Ado-Ekiti with higher population and humans’ activities compared to Ijero-Ekiti was less susceptible to pollution. Urbanization has no direct effects on sanitary surveys. The pH of wells’ water in Ado-Ekiti ranged from 4.8 - 8.2, EC (μS/cm) from 101 - 1008, while at Ijero-Ekiti, the pH and EC (μS/cm) varied from 2.1 - 13.8 and 80 - 1008 respectively. Ado-Ekiti wells’ water was more acidic than that of Ijero-Ekiti. Chemical concentrations (mg/L) of Ca<sup>2+</sup>, Mg<sup>2+</sup>, Na<sup>+</sup>, K<sup>+</sup>, , and Cl<sup>ˉ</sup> of the wells’ water in both cities were within WHO-approved standards for drinking water. However, with average concentrations of 142.17 (mg/L) and 252.71 (mg/L) at Ado-Ekiti and Ijero-Ekiti, respectively, exceeded the standard in many locations. Susceptibility to pollution classification employing TDS, NPI and MNPI showed that Ijero-Ekiti was more susceptible to pollution compared to Ado-Ekiti. This assertion was supported by statistical analysis employing correlation, cluster analysis, and principal component analysis. This study showed that urbanization had no direct effects on sanitary surveys and groundwater quality. Pollution of wells’ water in the two cities was, mainly from anthropogenic activities. However, Ijero-Ekiti, with significant anthropogenic activities, had its wells’ water more susceptible to pollution. Sanitary surveys are a complementary method to water quality monitoring. 展开更多
关键词 URBANIZATION Groundwater Quality Geogenic Contaminants Sanitary surveys HYDROCHEMISTRY Nitrate Pollution Index
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“Tasks”versus“Disciplines”:The Comprehensive Surveys of Natural Resources by the Chinese Academy of Sciences,and the Politics of Science Policy in the People’s Republic of China
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作者 张九辰 《Chinese Annals of History of Science and Technology》 2018年第1期123-139,共17页
As soon as the Chinese Academy of Sciences(CAS)was founded by the new government of the People’s Republic of China in 1949,the principles of“linking theory with practice”and“conducting research to serve the people... As soon as the Chinese Academy of Sciences(CAS)was founded by the new government of the People’s Republic of China in 1949,the principles of“linking theory with practice”and“conducting research to serve the people”set the framework for its scientific studies.How to balance their obligations to facilitate national economic construction with their desires to advance disciplinary scientific developments posed a knotty problem that frustrated those who organized and engaged in scientific research across the country,and in the CAS in particular.Against this background,the slogan“let tasks lead disciplines”was proposed as an effective solution.However,how exactly to put this into practice became a pressing issue,as CAS scientists and scholars debated the relationship between tasks and advances within scientific disciplines.This paper examines these debates as they were carried out in the case of the comprehensive surveys of natural resources organized by the CAS,focusing especially on different understandings of the relationship between“tasks”and“disciplines”within the CAS in the early 1960s,and examining the impact and legacy of“letting tasks lead disciplinary developments,”with possible lessons for the formulation of scientific plans today. 展开更多
关键词 “linking theory with practice ”tasks DISCIPLINES the Comprehensive surveys of Natural Resources Chinese Academy of Sciences
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The Importance of Selection Bias in Internet Surveys
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作者 Zerrin Asan Greenacre 《Open Journal of Statistics》 2016年第3期397-404,共8页
Nowadays, internet-based surveys are increasingly used for data collection, because their usage is simple and cheap. Also they give fast access to a large group of respondents. There are many factors affecting interne... Nowadays, internet-based surveys are increasingly used for data collection, because their usage is simple and cheap. Also they give fast access to a large group of respondents. There are many factors affecting internet surveys, such as measurement, survey design and sampling selection bias. The sampling has an important place in selection bias in internet survey. In terms of sample selection, the type of access to internet surveys has several limitations. There are internet surveys based on restricted access and on voluntary participation, and these are characterized by their implementation according to the type of survey. It can be used probability and non-probability sampling, both of which may lead to biased estimates. There are different ways to correct for selection biases;poststratification or weighting class adjustments, raking or rim weighting, generalized regression modeling and propensity score adjustments. This paper aims to describe methodological problems about selection bias issues and to give a review in internet surveys. Also the objective of this study is to show the effect of various correction techniques for reducing selection bias. 展开更多
关键词 Internet surveys Selection Bias Weighting Adjustment Procedures
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Economic recovery in Greater China—Surveys in Hong Kong and China's Mainland predict a positive outlook for both economies
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《China Economist》 2009年第5期123-126,共4页
Two surveys conducted in Hong Kong and China's Mainland reveal predictions of a quick recovery ahead for both economies.The surveys were conducted by CPA Australia,with the Hong Kong survey jointly sponsored by De... Two surveys conducted in Hong Kong and China's Mainland reveal predictions of a quick recovery ahead for both economies.The surveys were conducted by CPA Australia,with the Hong Kong survey jointly sponsored by Deloitte China and CPA Australia’s Hong Kong China division. 展开更多
关键词 over surveys in Hong Kong and China's Mainland predict a positive outlook for both economies Economic recovery in Greater China
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Using seismic surveys to investigate sediment distribution and to estimate burial fluxes of OC, N, and P in a canyon reservoir 被引量:4
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作者 Ningxiao Yu Yong Qin +2 位作者 Feng Hao Yunchao Lang Fushun Wang 《Acta Geochimica》 EI CAS CSCD 2019年第6期785-795,共11页
As a high-precision survey method,seismic surveying has been increasingly applied to inland water research,although its application to artificial reservoirs has remained limited.As a special artificial water body,rese... As a high-precision survey method,seismic surveying has been increasingly applied to inland water research,although its application to artificial reservoirs has remained limited.As a special artificial water body,reservoirs have important effects on the fluvial transport of material from land to ocean,and inevitably have complex terrain which can complicate and distort the results of seismic surveys.Therefore,there are still some problems need to be resolved in the application of seismic surveys in reservoirs with complex terrain.For this study,the Dongfeng Reservoir located in the upper reaches of the Wujiang River was chosen as an example to test the seismic survey method.Our testing showed that(1)because of the complex underwater terrain,the signal-to-noise ratio of the echo signal in canyon reservoir is low,making it difficult to determine sediment layers thicknesses in some areas;and(2)due to the large spatial heterogeneity of sediment distribution,insufficient density of cross-sections can lead to inaccurate interpolation results.To improve the accuracy of calculations,a mathematical method was used.Ultimately,the total burial mass of sediment was estimated at 2.85 x 107 tons,and the average burial rates of total organic carbon,total phosphorus,and total nitrogen were estimated at 0.194,0.011,and 0.014 g cm-2 year-1,respectively.These values were close to the results of previous studies and hydrographic station data,indicating that seismic survey can be a reliable and efficient method for the mapping of reservoirs. 展开更多
关键词 Dongfeng Reservoir Seismic survey SEDIMENTATION Nutrients burial fluxes
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