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排序方式: 共有1933条查询结果,搜索用时 15 毫秒
81.
虚拟能--解析中国能源消费超常规增长的新视角   总被引:6,自引:0,他引:6  
为了说明我国能源消费近年来高速增长的深层原因,提出了虚拟能的概念和计算方法,并计算出我国2002和2003年对外贸易中虚拟能净出口量分别为18 838.5万吨标煤和24 661.7万吨标煤。结论指出,我国虚拟能净出口量快速增长是导致我国近年来能源消费增长速度高于GDP增长速度的直接原因。  相似文献   
82.
应用特征光合色素研究东海和南海北部浮游植物的群落结构   总被引:23,自引:0,他引:23  
应用高效液相色谱并结合二极管阵列检测器分析技术,研究了东海与南海北部典型断面浮游植物的光合色素组成,进而由CHEMTAX软件估算浮游植物群落结构。结果表明:东海断面浮游植物叶绿素a生物量大于南海北部断面。受海水层化结构影响,东海PN断面浮游植物群落结构形成上层和下层两种类型,上层以蓝藻为主要优势类群;下层以硅藻为主要优势类群。南海北部S断面浮游植物群落形成近岸与离岸两种类型,近岸以硅藻、隐藻、绿藻为主要优势类群;离岸以定鞭金藻、蓝藻、原绿球藻为主要优势类群。初步分析了研究海区浮游植物群落结构与环境因子的关系。  相似文献   
83.
根据先秦考古遗址地理分布的分析和郭井子贝壳堤的发掘和调查,复原了6.5~5.0kaB.P. ,4.5~4.0kaB.P.和3.4~2.1kaB.P.的3条海岸线,它们大致与现代海岸线平行分布,年代自南向北逐渐年轻,揭示了山东北部地区全新世海侵和海退过程的主要环节,恢复了全新世海岸变迁的具体历程。对寿光大荒北央遗址出土盔形器内壁凝结物的XRF和XRD分析证明,本区沿海商周时期遗址出土的盔形器应是制盐器具,而沿海盔形器密集分布区与6.5~5.0kaB.P.的海岸线基本重合,表明商周时期海盐生产地域应在6.5~5.0kaB.P.和3.4~2.1kaB.P.的两条海岸线之间。本区的海盐生产与海岸变迁密切相关,人类适应环境和开发资源的主要手段就是从事海盐生产。在6.5~4.0kaB.P. ,人类在滨海地带有了初步的海盐生产,开始了适应环境和利用自然资源的最早尝试,在3.4~2.1kaB.P. ,人类又开始开采地下卤水生产海盐,使现今海拔9~10m以下的广阔地区成为产盐区。本区内陆的山前平原地带则是海盐的主要消费区,也是产盐区所需粮食和各种生产生活用品的供应区。这一分析对研究本区先秦时期的聚落功能演变具有重要意义,也是研究本区全新世人地关系演变的关键视角。  相似文献   
84.
藏北安多-巴青地区侏罗纪含礁层系岩相及沉积环境   总被引:3,自引:1,他引:2       下载免费PDF全文
根据岩性及其组合特征,本文将西藏北部安多—巴青地区侏罗纪含礁地层划分为流水成因的颗粒岩岩相、流水成因的碎屑岩岩相、复成因的泥晶—泥质灰岩岩相、生物及生物化学成因的障积岩岩相、生物及生物化学成因的粘结—障积岩岩相和生物及生物化学成因的骨架岩岩相等6大类型,计16种岩相。它们构成了潮坪相组合、台地浅滩相组合、开阔台地相组合和台地生物礁相组合共4种岩相组合,并由下而上有规律地形成2种岩相序列,即陆源碎屑与碳酸盐混合台地相序列和碳酸盐台地相序列。  相似文献   
85.
为分析南海北部海域油气勘探保障建设选址的适宜性,在广泛研究备选区特征资料的基础上,基于层次分析法(Analytic Hierarchy Process, AHP)原理,以自然环境因素、开发环境因素、基础设施与投资情况以及其他因素作为一级评判准则,建立了包括12项二级评判准则的递进层次结构模型,并以永兴岛、赵述岛和晋卿岛作为3个假定备选区,来验证分析评价模型的有效性和可靠性。AHP评判结果显示,3个备选区的整体优劣指数依次为0.587 1, 0.212 1, 0.200 8;AHP模型的一致性比例CR值为0.020 3。通过分析和筛选影响远海油气勘探保障建设的选址因子,构建基于AHP原理的选址评价模型,可用于分析评价南海北部岛礁油气勘探保障建设选址的适宜性。  相似文献   
86.
用北太平洋(含赤道太平洋区)1949~1979年的COADS资料,通过矢量EOF分解得到北太平洋异常风场的分布型及其时间变化规律。分析表明,EOF1~5场与大气活动中心、海洋相互作用有联系,具有明显的天气学意义。此外,还讨论了EOF异常风场间的转换及其季节性差异。  相似文献   
87.
Reef development varies considerably around the high, raised‐limestone islands of the Commonwealth of the Northern Mariana Islands (CNMI). Here we examine the modern assemblages at 30 sites for coral composition, colony density, colony size, and fidelity. We defined four reef types and hypothesize the presence of environmentally driven ecological stasis, whereby the environment continuously selects for coral species membership, defines colony sizes, and over time creates the noted reef types. Our results show that constructional spur‐and‐groove reefs supported significantly larger coral‐colony sizes and higher coral species richness compared with high‐relief interstitial framework, low‐relief incipient, and non‐constructional coral assemblages. Non‐constructional reefs supported much smaller coral colony sizes, despite similar population densities, and were consistently found in association with high wave exposure. The distinct coral assemblages found on interstitial framework and low‐relief incipient reefs were not affiliated with any wave exposure regime, but were located adjacent to large watersheds and on islands with unique geological history. These assemblages were nested within the spur‐and‐groove species pool. Overall, modern coral cover was well predicted by bathymetric slope and watershed size, while species richness was additively influenced by two proxies of pollution, suggesting the latter is better suited for establishing management targets. In contrast with previous studies that suggested modern assemblages were biologically controlled in the CNMI, we show reef assemblages and reef development are highly influenced by long‐term environmental forcing.  相似文献   
88.
Shallow marine carbonate sedimentation dominated during the Albian in the western part of the Basque Cantabrian Basin in Northern Spain, forming the large Ramales Platform. This platform originated on a less subsiding tectonic block facing deeper and more subsiding areas to the south and east, which were created by tectonic activity in the Basin. Fracture-related hydrothermal dolomites hosted in these Albian carbonates are well exposed in the Asón valley area. Mapping in the studied area revealed several dolomite bodies related to main faults that cut the stratification almost at right angles. The bodies show a vertical development along fault-strike up to 900 m thick from which kilometre-scale branches expand following the stratification. Dolomitization is pervasive and independent of the limestone facies. Main dolomite facies are fine replacive, sucrosic and saddle. Petrography, C, O and Sr isotopes and fluid-inclusion analysis support a polyphase hydrothermal dolomitization at fluid temperatures between 75 °C and 240 °C and highly variable salinity of up to 22 wt.% NaCl. Fine dolomite replaced limestone first and then, sucrosic and saddle dolomites replaced part of the first dolomite and cemented newly created fracture porosity together with different calcite cements. Zebra dolomites and hydroclastic breccias are products of this later stage. Burial analysis of the host rock supports maximum burial temperatures of 80 °C and intense tectonic activity from the Albian to Turonian with a latest Albian peak subsidence. Albian stretching of the crust and subsequent ascent of the isotherms in the area is suggested to have produced sufficient heat to the dolomitizing fluids. The structural analysis indicates a strong transtensional tectonic activity in the studied area during Albian to Turonian time with the creation of an overstep between W–E trending and N–S trending faults. Fluids moved from subsiding areas to fractured uplifted parts of the Ramales Platform, enhanced by diapiric activity.  相似文献   
89.
Three-dimensional liquid sloshing in a tank with baffles   总被引:1,自引:0,他引:1  
A numerical model has been developed to study three-dimensional (3D) liquid sloshing in a tank with baffles. The numerical model solves the spatially averaged Navier-Stokes equations, which are constructed on a non-inertial reference frame having six degree-of-freedom (DOF) of motions. The large-eddy-simulation (LES) approach is employed to model turbulence by using the Smagorinsky sub-grid scale (SGS) closure model. The two-step projection method is employed in the numerical solutions, aided by the Bi-CGSTAB technique to solve the pressure Poisson equation for the filtered pressure field. The second-order accurate volume-of-fluid (VOF) method is used to track the distorted and broken free surface. The baffles in the tank are modeled by the concept of virtual boundary force (VBF) method. The numerical model is first validated against the available analytical solution and experimental data for two-dimensional (2D) liquid sloshing in a tank without baffles. The 2D liquid sloshing in tanks with baffles is then investigated. The numerical results are compared with other results from available literatures. Good agreement is obtained. Finally, the model is used to study 3D liquid sloshing in a tank with vertical baffles. The effect of the baffle is investigated and discussed.  相似文献   
90.
Based on the comprehensive collection of the field observed salinity of the Bohai Sea (BHS) and the northern Huanghai Sea (NHS) from the 1950s to the present,the patterns of 10-years-averaged salinity at the different layers in the recent five decades (the 1950s,the 1960s,the 1970s,the 1980s and the 1990s) are obtained by the spatial-temporal interpolation technique with the scrupulous data quality control in this study.Then,by combining the spatial-temporal interpolation technique with successive correction method,the annual distributions of salinity both in the BHS and in the NHS are obtained as well.The data analyses indicate that the overall salinity in the BHS and the NHS increases from the 1960s till the present,with the increase of annual mean salinity of 0.04 psu from the 1950s,and the maximum increase rate of salinity is about 0.14 psu/a in the Bohai Bay.The high salinity tongue extended significantly from the NHS into the BHS.The intensified eastern wind field is related to the western intrusion of the NHS warm current,which probably leads to the moving forward of the high salinity water mass into the BHS.However,it is rather different from the salinity distribution characteristics between the 1950s and the 1960s.The extensive precipitation in the 1960s could lead to an increase in the discharge of the Huanghe River,which might result in the decrease of salinity in the BHS.But the salinity isoline of 32 in the NHS still extended significantly into the BHS in the 1960s.Since the 1980s,the patterns of salinity distribution have changed thoroughly.The salinity in the central area of the BHS was low,while the salinity in the Bohai Bay and the Liaodong Bay was higher than the other regions with its horizontal salinity gradient decreasing in the 1980s.The Empirical Orthogonal Function Analysis (EOF) is also conducted to study the interannual salinity variability of the BHS and the NHS.The correlation coefficient between the time coefficient series of the main mode and the Huanghe River discharge can reach -64.57%.It can be concluded that salinity variation of the BHS and the NHS has strong negative correlation with the Huanghe River discharge.  相似文献   
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