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Prevalence of lactase persistent/non-persistent genotypes and milk consumption in a young population in north-west Russia 被引量:2
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作者 Yulia Khabarova Suvi Torniainen +3 位作者 Hanna Nurmi Irma Jrvel Mauri Isokoski Kari Mattila 《World Journal of Gastroenterology》 SCIE CAS CSCD 2009年第15期1849-1853,共5页
AIM: TO estimate the prevalence of the lactase non-persistent genotype (C/C-23910) in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase ... AIM: TO estimate the prevalence of the lactase non-persistent genotype (C/C-23910) in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase activity. METHODS: Blood samples for genotyping lactase activity, defining the C/T-13910 variant by polymerase chain reaction, and direct sequencing were taken from 231 medical students of Russian origin aged 17-26 years. We analyzed milk product consumption by questionnaire which was specially designed for the estimation of milk consumption and abdominal complaints. RESULTS: We found that the prevalence of the C/C-13190 genotype in the northern Russian population was 35.6%. The other genotypes nearby C/T-13910 and associated with lactase activity were not present in the study population. The consumption of milk among people with the non-persistent genotype tended to be lower than among the lactose tolerant subjects, but was not statistically significant. CONCLUSION: An investigation of the lactase persistent genotype in a northern Russian population has not been performed before, The genotype did not affect the consumption of milk products in this population which could be explained by low consumption of milk products among the entire study population. 展开更多
关键词 C/C-13910 genotype Hypolactasia Lactasepersistence/non-persistence Lactose malabsorption Milk consumption north-west Russia
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Soil Properties and Land Capability Evaluation in a Mountainous Ecosystem of North-West Cameroon 被引量:3
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作者 P. Azinwi Tamfuh E. Temgoua +2 位作者 P. Wotchoko A. Boukong D. Bitom 《Journal of Geoscience and Environment Protection》 2018年第7期15-33,共19页
Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study s... Up to date, tropical mountainous ecosystems still lack in depth information on soil and environmental characteristics which are major factors limiting optimum crop production. The objective of this work was to study soil characteristics and to evaluate the land capability level for the production of some common tropical crops in mountainous ecosystem soils of North West Cameroon. Soil sampling was done following a randomized complete block design (RCBD) with four replications for three topographic positions (upslope, midslope and footslope) and at two depths (0 - 20 cm and 20 - 100 cm). It was completed by standard laboratory analyses. The fertility capability classification (FCC) system enabled to identify soil limitations and to classify soils into FCC units. Land and climate were evaluated by simple limitation and parametric methods. Globally, the soils were dark-colored, sandy clayey to clayey, compact and very acidic (pHH2O = 4.3 - 5.8). The organic matter (3.7% - 5.1% dry matter), total nitrogen (0.08% - 0.56%) and available phosphorus (22.1 to 30.9 mg?kg?1) recorded for the 0 - 20 cm depth then reduced with depth but midslope values were also lower. The C/N ratio varied between 9 and 45. Low C/N values appeared mostly in 0 - 20 cm depth at the upslope and downslope soils and subsurface soils of midslope position. Exchangeable Ca was very low to low (1.43 - 3.6 cmol + kg?1), Mg was very low to low (0.39 - 1.5 cmol + kg?1), K was low to medium (0.2 - 0.54 cmol + kg?1) and Na was very low (?1). The sum of exchangeable bases was very low (3.02 - 5.19 cmol + kg?1), cation exchange capacity was low to moderate (8.60 - 25.6 cmol + kg?1) and base saturation was very low to low (19.27% - 36.97%). Leaching of bases under heavy rainfall is a major cause of soil acidification under humid topical ecosystems. The Ca/Mg/K ratio was unbalanced and Mg was the most relatively concentrated base in all the soils. There was a clear variation of most of the soil properties along the slope and with depth. The soils were classified in the FCC system as aek for the upslope soils, Caek for the midslope soils and Cagk for the footslope soils. The principal limitations to production of huckleberry, beans, maize and potatoes were heavy rainfall, wetness, steep slope, soil texture/structure and low soil fertility. These constraints might be overcome by farming at the end of the raining season, contour ploughing, terracing, fertilization and liming. 展开更多
关键词 Land EVALUATION Fertility Capability EVALUATION Nutrient Status Mountainous ECOSYSTEM Bafut north-west Cameroon
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Assessment of Heavy Metal Pollution of the Peter the Great Bay (North-West Pacific Region) Using Brown Algae
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作者 Svetlana Kozhenkova Elena Chernova 《Journal of Geoscience and Environment Protection》 2020年第10期134-146,共13页
<div style="text-align:justify;"> According to the content of heavy metals Fe, Mn, Cu, Zn, Pb, Cd and Ni in brown algae <em>Sargassum miyabei</em> from the Peter the Great Bay of the Sea of... <div style="text-align:justify;"> According to the content of heavy metals Fe, Mn, Cu, Zn, Pb, Cd and Ni in brown algae <em>Sargassum miyabei</em> from the Peter the Great Bay of the Sea of Japan, geochemical factors were calculated. The algae geochemical anomaly index (I<sub>GA</sub>) characterizes the degree of excess of the background concentrations of metals. The heavy metal pollution factor (F<sub>p</sub>) is used to estimate the degree of pollution of the marine environment with heavy metals. The Peter the Great Bay has a low level of heavy metal pollution, but some parts of second-order bays, such as Amurskii Bay, Ussuriiskii Bay and Vostok Bay, have a moderate degree of pollution. The high pollution level was registed on the western coast of the Ussuriiskii Bay near the Vladivostok city landfill. Thirty percent of sampling stations were noted to have higher threshold levels of metals in the algae. These areas need to be monitored to assess their environmental status and measures should be applied to reduce the impact on the environment. </div> 展开更多
关键词 BIOMONITORING Heavy Metals Environmental Quality Regulation Brown Algae Sargassum miyabei north-west Pacific Region
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Typology of Local Construction Materials from the Adamawa and North-West Regions of Cameroon
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作者 Zo’o Zame Philémon Nzeukou Nzeugang Aubin +3 位作者 Uphie Chinje Melo Mache Jacques Richard Ndifor Divine Azigui Nni Jean 《Geomaterials》 2016年第2期50-59,共10页
This article summarizes the different local construction materials observed in two regions of Cameroon (Adamawa and North-West). These raw materials were mapped and evaluated using various methods of investigation (sp... This article summarizes the different local construction materials observed in two regions of Cameroon (Adamawa and North-West). These raw materials were mapped and evaluated using various methods of investigation (spatial distribution, estimation of reserves, development of a database compatible with geo-referenced maps). The results obtained show three types of local construction materials (vegetal, pedological and geological) with quantitative estimation or distribution. Vegetal local materials include herbaceous savanna with strong dominance of straw in Adamawa region than the North West region. Pedological local construction materials include lateritic soils (ferruginous or clayey), harplan, sandy clay and sandy clay soil while geological local construction materials include volcanic, plutonic and metamorphic rocks. Many sites of these geological materials are suitable for the rock quarry plant. Adamawa region also contains sedimentary rocks constituted by metamorphic conglomerate and sandstones. Two main types of residential homes are constructed with these local construction materials in these regions of Cameroon. These include huts and houses. 展开更多
关键词 Local Construction Materials TYPOLOGY Adamawa and north-west Regions Cameroon
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Alternative schemes of groundwater supply in north-west Bulgaria
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《Global Geology》 1998年第1期9-9,共1页
关键词 Alternative schemes of groundwater supply in north-west Bulgaria
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Underground salt water intrusion and ecological environments in inland north-west China
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《Global Geology》 1998年第1期45-46,共2页
关键词 Underground salt water intrusion and ecological environments in inland north-west China
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气候变化对南水北调西线工程的影响及建议
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作者 王国庆 虞畅 +3 位作者 金君良 宁忠瑞 王云 孙高霞 《人民黄河》 CAS 北大核心 2024年第9期60-66,共7页
南水北调工程是国家水网的重要组成部分,其西线工程建设是缓解我国西北、华北地区水资源短缺的重要举措。气候变化下西线工程引水区和受水区水资源情势直接关系到工程的规划建设与运行方式。基于历史实测资料和气候模式情景,采用数理统... 南水北调工程是国家水网的重要组成部分,其西线工程建设是缓解我国西北、华北地区水资源短缺的重要举措。气候变化下西线工程引水区和受水区水资源情势直接关系到工程的规划建设与运行方式。基于历史实测资料和气候模式情景,采用数理统计与水文模拟相结合的途径分析了气候变化对南水北调西线工程引水区和受水区水资源的影响。结果表明:1)1961—2020年西线调水区和受水区气候变化以暖湿化为主要特征,调水区年径流量整体稳定略增,受水区年径流量显著性减少。2)未来中期(2035年)和远期(2050年),调水区和受水区气温继续显著升高,降水多呈非显著增加;未来中期、远期调水区年径流量较基准期(1961—2000年)分别增加1.42%和2.08%,受水区年径流量分别减少1.02%和0.28%。3)未来气候变化下,调水区年径流量相对稳定,能够满足调水需求,受水区年径流量略减,对跨流域调水需求有所增加。为确保南水北调西线工程的长期稳定运行,建议加强气候变化及其影响的不确定性研究,制定科学合理的应对措施,以应对未来可能的水资源短缺的挑战。 展开更多
关键词 气候变化 RCCC-WBM模型 水资源 南水北调西线工程
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南水北调西线工程上线水源区大型底栖动物群落结构及环境驱动因子 被引量:4
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作者 张丰搏 胡鹏 +3 位作者 闫龙 唐家璇 闫肖瑶 王玉莲 《水资源保护》 EI CSCD 北大核心 2024年第1期135-141,共7页
为评估南水北调西线工程上线水源区大型底栖动物群落结构及环境驱动因子,于2022年7月(汛期)和11月(非汛期)开展监测采样工作。采用生物多样性指数和丰度-生物量比较曲线(ABC曲线)作为大型底栖动物群落特征参数,分析大型底栖动物群落在... 为评估南水北调西线工程上线水源区大型底栖动物群落结构及环境驱动因子,于2022年7月(汛期)和11月(非汛期)开展监测采样工作。采用生物多样性指数和丰度-生物量比较曲线(ABC曲线)作为大型底栖动物群落特征参数,分析大型底栖动物群落在水源区的结构,并对其进行多元排序和Pearson相关性分析。结果表明:共采集45种大型底栖动物,隶属于4门5纲10目32科44属,其中优势种8种,所有优势物种出现频率均大于50%,水源区大型底栖动物群落结构一致性较高;水源区Margalef丰富度指数、Shannon-Wiener多样性指数和Pielou均匀度指数均值分别为4.01、1.68、0.61;多数采样区域大型底栖动物的ABC曲线呈纠缠态势,其丰度和生物量累积百分比的差值面积在0附近波动,群落以小个头物种为主;优势种以耐污值低的敏感种类为主,说明河流几乎不受污染,水体清洁;pH值是影响水源区大型底栖动物群落结构的主要环境驱动因子。 展开更多
关键词 南水北调西线工程 大型底栖动物群落 生物多样性指数 ABC曲线 环境驱动因子
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Unconformity structures controlling stratigraphic reservoirs in the north-west margin of Junggar basin, North-west China 被引量:14
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作者 Kongyou WU Douglas PATON Ming ZHA 《Frontiers of Earth Science》 SCIE CAS CSCD 2013年第1期55-64,共10页
Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weat... Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weath- ering, leaching, and onlap. At the same time, the structural body may be divided into three layers, including upper layer, mid layer, and lower layer. The upper layer with good primary porosity serves as the hydrocarbon migration system, and also accumulates the hydrocarbon. The mid layer with compactness and ductility can play a role as cap rock, the strength of which increases with depth. The lower layer with good secondary porosity due to weathering and leaching can form the stratigraphic truncation traps. A typical stratigraphie reservoir lying in the unconformity between the Jurassic and Triassic in the north-west margin of the Junggar basin was meticulously analyzed in order to reveal the key controlling factors. The results showed that the hydrocarbon distribution in the stratigraphic onlap reservoirs was controlled by the onlap line, the hydro- carbon distribution in the stratigraphic truncation reser- voirs was confined by the truncation line, and the mid layer acted as the key sealing rock. So a conclusion was drawn that "two lines (onlap line and truncation line) and a body (unconformity structural body)" control the formation and distribution of stratigraphic reservoirs. 展开更多
关键词 unconformity structural body stratigraphicreservoir key controlling factors Jurassic bottom north-west margin of the Junggar basin
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Dietary Diversity and Food Security Status among Cameroonian Adults Living in Semi-Urban Areas: A Cross-Sectional Study
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作者 Tonou Boris Ronald Tchuente Pauline Vervaine Hagbe +6 位作者 Eliane Flore Eyenga Kemadjou Ruth Edwige Dibacto Ngassa Dany Joël Ngoumen Fotso Janvier Aime Youovop Nguemto Roussel Guy Takuissu Judith Laure Ngondi Julius Enyong Oben 《Food and Nutrition Sciences》 CAS 2024年第7期548-564,共17页
Introduction: Food security is one of the greatest challenges that most African countries face. It is a concept that considers not only food quantity but also food quality. The objective of this study was to describe ... Introduction: Food security is one of the greatest challenges that most African countries face. It is a concept that considers not only food quantity but also food quality. The objective of this study was to describe dietary diversity and food security status at the individual level in Cameroonian populations. Methods: A total of 1180 men and women aged 20 and over and living in the West, North West, and Littoral regions of Cameroon were recruited. Data on dietary habits were collected through the frequency of consumption of various food groups. Dietary diversity was assessed using a 24-hour dietary recall. Food security status was determined by combining two indicators (food consumption score and individual food diversity score). Results: The mean dietary diversity score of the population was 3.53 ± 1.44, p Conclusion: The diet diversity of adults living in the West, North West, and Littoral regions of Cameroon is medium. Although half of the study population was food secure, there is a need to implement food security policies further to reduce food insecurity among the Cameroonian population. 展开更多
关键词 Dietary Diversity Individual Food Security LITTORAL WEST North West Cameroon
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基于多方法综合比较的南水北调西线工程水源区生态需水研究
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作者 王玉莲 杨泽凡 +5 位作者 闫龙 刘欢 曾庆慧 杨钦 闫肖瑶 胡鹏 《水资源保护》 EI CAS CSCD 北大核心 2024年第4期137-147,共11页
针对南水北调西线工程调水需求,以方法比选、目标修正、可行性验证为主线,提出了一套多方法综合确定水源区生态需水过程的思路,并制定了10个坝址断面枯水期和非枯水期的生态基流、敏感生态需水及年生态水量目标。结果表明:水源区坝址断... 针对南水北调西线工程调水需求,以方法比选、目标修正、可行性验证为主线,提出了一套多方法综合确定水源区生态需水过程的思路,并制定了10个坝址断面枯水期和非枯水期的生态基流、敏感生态需水及年生态水量目标。结果表明:水源区坝址断面枯水期生态基流在多年平均流量中的占比约为20%,非枯水期占比约为40%;3—6月为鱼类集中产卵敏感期,需要每月发生一次脉冲流量过程,每次至少持续10 d,脉冲流量在多年平均流量中的占比为48%~73%;各坝址断面年均生态水量在多年平均径流量中的占比约为70%,其中丰水年、一般偏枯年、枯水年生态水量占比分别为68%~78%、66%~75%和61%~70%;研究结果符合长江流域现有管控要求,具备较好的现实可达性。 展开更多
关键词 生态需水 生态基流 敏感生态需水 年生态水量 南水北调西线工程
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高速铁路与城市群发展社会经济效应探究
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作者 张宇 林玉红 《铁道经济研究》 2024年第3期1-8,共8页
城市群作为高度一体化、同城化的城市集群,在引领区域经济发展、高效配置资源、推动技术变革,以及提高区域经济活力等方面起着关键作用,同时高速铁路发挥着至关重要的助推作用。在阐释高速铁路与城市群发展关联关系的基础上,从城市交通... 城市群作为高度一体化、同城化的城市集群,在引领区域经济发展、高效配置资源、推动技术变革,以及提高区域经济活力等方面起着关键作用,同时高速铁路发挥着至关重要的助推作用。在阐释高速铁路与城市群发展关联关系的基础上,从城市交通可达性、绿色低碳发展、经济要素流动、产业发展、营商环境及全要素生产率等不同维度,探讨高速铁路与城市群发展的社会效应和经济效应,提出高速铁路与城市群发展社会经济效应策略,即:优化高速铁路网络布局,实现城市群内外通道联通;促进轨道交通“四网融合”发展,扩大高速铁路服务辐射范围;优化高速铁路客运产品系列,充分衔接城市群交通方式;优化高铁快运产品系列,大力增强城市群物流联系。 展开更多
关键词 高速铁路 城市群 高速铁路网 “八纵八横” 社会效应 经济效应 “四网融合” 绿色低碳
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Estimation of environmental effects of photovoltaic generation in North-west China
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作者 Mengjia REN Anastasia SHCHERBAKOVA 《Frontiers in Energy》 SCIE CSCD 2013年第4期535-543,共9页
In estimating emissions reductions brought about by renewables in China, much of existing research assumes that renewables displace coal power. In this paper, this assumption is challenged and the potential environmen... In estimating emissions reductions brought about by renewables in China, much of existing research assumes that renewables displace coal power. In this paper, this assumption is challenged and the potential environmental effects of photovoltaic (PV) power in North-west China are reevaluated when the marginal generator actually being displaced is taken into account. The annual PV power generation in the North-west Grid is estimated, in this paper, to be as high as 17900GW.h in 2015, roughly equaling to the output of 1.5 nuclear power plants in the US today. The total associated emission reduction in 2015 will at most be 0.36 percent of SO2 and 0.25 percent of NOx emissions from their 2010 levels in China. Further, PV power may render no emissions reduction at all if it displaces hydropower, which is often used to meet peak demand in the North-west Grid in China. These results imply that a more cost-effective area of focus in the short- term may be on desulfurization and denitrification technologies for coal plants. 展开更多
关键词 photovoltaic (PV) emission reduction North- west China marginal generator
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东西差距还是南北差距?——1978年以来中国区域差距的演变与机理分析 被引量:19
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作者 安树伟 李瑞鹏 《中国软科学》 CSCD 北大核心 2023年第4期109-120,共12页
1978—2021年,中国区域绝对差距一直是扩大的,而相对差距经历了先缩小、后扩大、再缩小、基本稳定4个阶段。中国的东西差距一直大于南北差距,2013年以来扭转的南北差距需要引起高度重视。中国区域差距是资源禀赋、区域战略与政策、要素... 1978—2021年,中国区域绝对差距一直是扩大的,而相对差距经历了先缩小、后扩大、再缩小、基本稳定4个阶段。中国的东西差距一直大于南北差距,2013年以来扭转的南北差距需要引起高度重视。中国区域差距是资源禀赋、区域战略与政策、要素流动、市场需求、市场化水平和文化传统等多因素作用的结果,未来中国需要精准的区域政策以调控区域差距。 展开更多
关键词 区域总体差距 东西差距 南北差距 演变机理
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黄河几字弯水网:南水北调西线配套东延工程构想 被引量:1
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作者 赵勇 王浩 +3 位作者 邓铭江 何国华 何凡 汪勇 《水利学报》 EI CSCD 北大核心 2023年第9期1015-1024,共10页
黄河几字弯区是黄河流域生态保护和高质量发展重大国家战略实施的核心区,但区域发展长期受到水资源短缺的严重制约。提出的黄河几字弯水网构想是借助南水北调西线调水入洮河的方案,充分利用洮河与黄河几字弯区高程差,以隧洞形式穿越洮... 黄河几字弯区是黄河流域生态保护和高质量发展重大国家战略实施的核心区,但区域发展长期受到水资源短缺的严重制约。提出的黄河几字弯水网构想是借助南水北调西线调水入洮河的方案,充分利用洮河与黄河几字弯区高程差,以隧洞形式穿越洮河与渭河分水岭,向陇东黄土高原等地区延伸,全程自流引水到几字弯中部白于山高地,形成人工“水脊”,并以此为轴线,东、北、南自流辐射三大发展带,由此形成“一轴三带十片”黄河几字弯水网整体框架。按照供水目标分级规划、分步实施的思想,推荐适宜调水规模为25亿~54亿m^(3)。黄河几字弯水网是南水北调西线配套东延工程构想,是对南水北调西线配套工程的优化完善,可以实现高水高用、专线专用,还可以打通南水北调西线输水“渭河通道”,实现“三线配水”的优化格局,并通过引汉济渭工程与南水北调中线“互补互济”,提高南水北调中线受水区和几字弯区供水保障率。建设黄河几字弯水网对系统破解区域水资源制约问题,促进黄河流域生态保护和高质量发展具有重要意义。 展开更多
关键词 黄河 几字弯水网 南水北调西线 高质量发展
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南水北调西线工程水源区生态需水研究 被引量:5
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作者 尹炜 翟红娟 +2 位作者 邓志民 赵彦伟 陈炼钢 《人民长江》 北大核心 2023年第6期41-46,65,共7页
可调水量一直是南水北调西线工程争论的焦点,水源区生态需水是合理确定西线工程可调水量的重要依据。分析了南水北调西线工程水源区的生态环境特征、主要生态环境保护对象,并针对西线工程水源区生态需水研究现状及存在问题提出了需要重... 可调水量一直是南水北调西线工程争论的焦点,水源区生态需水是合理确定西线工程可调水量的重要依据。分析了南水北调西线工程水源区的生态环境特征、主要生态环境保护对象,并针对西线工程水源区生态需水研究现状及存在问题提出了需要重点研究的关键科学问题:生态需水应统筹考虑川陕哲罗鲑等关键物种、河岸植被等优势群落、干旱河谷等典型生态系统,深入研究高寒脆弱区关键保护对象对水文过程的响应规律,以及协调节点-河段-河流廊道多尺度、物种-生境-生态系统多目标的生态流量需求核算。此外,提出了“识别特殊需求-建立响应关系-统筹核算水量”的生态需水研究思路,以及节约用水、科学研究、关键技术等方面的区域生态环境保护工作建议。 展开更多
关键词 生态需水 高寒脆弱区 干旱河谷 川陕哲罗鲑 南水北调西线工程
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西北联大汉中分立院校战后教育复员考述——基于民国时期报刊的考察与分析
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作者 张显锋 张捷菲 孟小华 《陕西理工大学学报(社会科学版)》 2023年第1期62-70,共9页
抗战胜利,高等教育复员是中国高等教育发展历程的重要一环。依据多年来收集整理的“西北联大”专题性第一手民国报刊(以报为主)材料,运用报刊文献调查法,对西北联大汉中办学的分立院校战后复员的历史渊源、过程等予以关注,结合相关文献... 抗战胜利,高等教育复员是中国高等教育发展历程的重要一环。依据多年来收集整理的“西北联大”专题性第一手民国报刊(以报为主)材料,运用报刊文献调查法,对西北联大汉中办学的分立院校战后复员的历史渊源、过程等予以关注,结合相关文献进行系统考察、梳理、分析和研究,旨在揭示这一过程的历史事实与规律,并呈现这一过程中的诸多历史细节,对西北联大分离发展、战后复员及汉中社会区域研究等重要问题予以探讨。 展开更多
关键词 西北联大分立院校 西北大学 西北工学院 西北医学院 战后教育复员
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寻求南水北调西线项目的替代性方案
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作者 周民良 《开发研究》 2023年第4期1-12,共12页
鉴于我国水资源南北区域分布不均衡,20世纪50年代开始党中央就提出南水北调工程。2002年,《南水北调工程总体规划》获得国务院批准,规划建设东线、中线、西线工程。目前中线、东线一期工程已经建成通水,南水北调后续工程是否为西线工程... 鉴于我国水资源南北区域分布不均衡,20世纪50年代开始党中央就提出南水北调工程。2002年,《南水北调工程总体规划》获得国务院批准,规划建设东线、中线、西线工程。目前中线、东线一期工程已经建成通水,南水北调后续工程是否为西线工程、西线工程何时开工为各方关注。但从工程安全性、经济合理性角度出发,南水北调西线工程都应放弃。取而代之的,把更多黄河之水用于中上游地区,增设中上游短距离引黄工程。与此同时,可增加南水北调中线、东线向北调水量,以满足黄河中上游用水增加时中下游的用水需求。除此而外,可以采取节水、节约粮食、海水淡化、南水南调、优化经济结构多种政策管理方式,进一步改善我国南北区域的用水需求。 展开更多
关键词 南水北调 西线 替代方案 黄河引水工程 中线 东线
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广东元湾金矿床成因:来自稀土元素和流体包裹体的证据 被引量:1
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作者 陆一敢 肖益林 +3 位作者 周奇明 陶明荣 王晓霞 余成龙 《大地构造与成矿学》 EI CAS CSCD 北大核心 2023年第4期810-823,共14页
广东元湾金矿床是近年新发现且有潜力的金矿床,为了揭示成矿物质来源和矿床成因,对该矿床的黑云二长花岗岩、花岗闪长岩、含碳质泥岩、石英脉等进行稀土元素和流体包裹体研究。分析结果显示,稀土元素总量(∑REE)平均含量由高到低依次为... 广东元湾金矿床是近年新发现且有潜力的金矿床,为了揭示成矿物质来源和矿床成因,对该矿床的黑云二长花岗岩、花岗闪长岩、含碳质泥岩、石英脉等进行稀土元素和流体包裹体研究。分析结果显示,稀土元素总量(∑REE)平均含量由高到低依次为:含碳质泥岩(182×10^(-6))>黑云二长花岗岩(105×10^(-6))>花岗闪长岩(95.1×10^(-6))>石英脉(19.0×10^(-6))。其中,含碳质泥岩与华南黑色岩系的稀土元素组成相近,是金矿的主要源岩。黑云二长花岗岩的LREE/HREE为1.2~6.8,δEu为0.01~0.24,整体表现为强烈的Eu负异常和四分组效应,属于高分异演化花岗岩,与华南燕山期重熔花岗岩类的稀土元素特征一致,可能为金矿提供必要的成矿物质。δCe负异常反映了寒武系牛角河组(Є1n)形成于相对氧化的滨海‒浅海环境,有利于金矿初始富集。Eu、Ce呈负异常,反映黑色岩系形成于气候干燥的陆棚边缘浅海氧化环境。岩相学观察、显微测温指示流体包裹体类型主要为气‒液两相包裹体和少量含CO_(2)三相包裹体,属于中‒低温(均一温度181.4~204.3℃)的CO_(2)-NaCl-H_(2)O体系,具有低盐度(0.18%~24.46%NaCleqv),且在成矿过程中,含矿流体可能经历了流体不混溶作用。在中‒低温和剪切带相对还原条件下,金矿在构造有利部位发生沉淀是该矿床成矿的关键。 展开更多
关键词 粤西‒桂北 元湾金矿 稀土元素 流体包裹体 钦‒杭成矿带
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西、北江三角洲洪水位对洪水归槽与河床下切的响应 被引量:3
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作者 刘培 黄鹏飞 +1 位作者 许劼靖 陈秋伶 《南水北调与水利科技(中英文)》 CAS CSCD 北大核心 2023年第3期501-511,共11页
受流域洪水归槽造成水位抬升和区域河床下切引起水位下降影响,珠江三角洲泄洪情势发生了显著变化。为探明这种影响和变化,利用洪水、地形实测资料,分析当前洪水归槽和地形下切态势,基于河网二维水动力学模型,分别量化洪水归槽和地形下... 受流域洪水归槽造成水位抬升和区域河床下切引起水位下降影响,珠江三角洲泄洪情势发生了显著变化。为探明这种影响和变化,利用洪水、地形实测资料,分析当前洪水归槽和地形下切态势,基于河网二维水动力学模型,分别量化洪水归槽和地形下切对西、北江三角洲泄洪能力的作用大小,并在此基础上评估现状主干河道过流能力。结果表明:洪水归槽导致珠江三角洲防洪压力陡增,相对20世纪90年代,防洪控制断面思贤滘50年一遇设计洪峰流量增幅达11.7%,西江、北江相应洪水位最大抬升幅度分别为0.67、0.56 m;河道大规模下切增加了河道泄洪能力,1999—2016年西、北江主干河道平均下切幅度分别为2.54、1.21 m,相应的洪水位普遍降低,50年一遇重现期洪水位最大降幅分别西江为0.76 m、北江为0.67 m;除三角洲上部局部河段外,洪水归槽对三角洲洪水位抬升作用显著大于河道下切的水位降低作用。现状三角洲主干河道50年一遇洪水位有近900 km河段超堤防设计水位,超出河段主要集中在天河、南华、三善滘附近的三角洲腹部。研究成果可为后续珠江三角洲防洪体系整体安全评估和提升提供依据。 展开更多
关键词 西、北江三角洲 洪水归槽 河床下切 泄洪能力
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