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61.
低分子肝素作为一种抗血栓的多糖药物在临床中已应用了二十多年 ,目前已作为外科预防血栓形成药物 ,并在治疗急性静脉栓塞紊乱方面取代了未分级肝素。因肝素的来源和制备的方法不同使低分子肝素的精细结构不同 ,低分子肝素结构的复杂性 ,使得各产品的生物活性 ,例如抗蛋白酶活性不同 ,从而导致其临床使用的标准不同。该文将对低分子肝素的制备方法及其结构和抗蛋白酶活性的差异进行报导  相似文献   
62.
水动力作用下管道稳定性的试验研究   总被引:2,自引:2,他引:2  
利用振荡流水槽在以下两种约束条件下,研究波浪作用下直接铺设于砂质海底的管道失稳临界条件:1)管道两端自由;2)管道可水平、垂直自由运动,但流动受到限制。试验结果表明,管重无量纳数G与管道失稳的临界Fr数之间大致呈线性关系,而当G超过一定数值时,管道是侧向稳定的。管道的约束条件、砂床特性和加载速度对管道稳定性均有影响。  相似文献   
63.
根据水资源对厄尔尼诺事件的响应,得出了钱塘江流域水资源的统计预报模式:(1)在春季型厄尔尼诺事件的当年和夏季型厄尔尼诺事件的次年,金华站年径流量的距平一般都大于零:(2)厄尔尼诺事件的结束时间若超过5月1日,那么次年金华站年径流量的距平一般都大于零;(3)厄尔尼诺事件的强度越大。对钱塘江流域水资源的影响也越大。这对该流域长期及超长期的水资源预报具有重要的指示作用。  相似文献   
64.
The China Seas include the South China Sea, East China Sea, Yellow Sea, and Bohai Sea. Located off the Northwestern Pacific margin, covering 4700000 km~2 from tropical to northern temperate zones, and including a variety of continental margins/basins and depths, the China Seas provide typical cases for carbon budget studies. The South China Sea being a deep basin and part of the Western Pacific Warm Pool is characterized by oceanic features; the East China Sea with a wide continental shelf, enormous terrestrial discharges and open margins to the West Pacific, is featured by strong cross-shelf materials transport; the Yellow Sea is featured by the confluence of cold and warm waters; and the Bohai Sea is a shallow semiclosed gulf with strong impacts of human activities. Three large rivers, the Yangtze River, Yellow River, and Pearl River, flow into the East China Sea, the Bohai Sea, and the South China Sea, respectively. The Kuroshio Current at the outer margin of the Chinese continental shelf is one of the two major western boundary currents of the world oceans and its strength and position directly affect the regional climate of China. These characteristics make the China Seas a typical case of marginal seas to study carbon storage and fluxes. This paper systematically analyzes the literature data on the carbon pools and fluxes of the Bohai Sea,Yellow Sea, East China Sea, and South China Sea, including different interfaces(land-sea, sea-air, sediment-water, and marginal sea-open ocean) and different ecosystems(mangroves, wetland, seagrass beds, macroalgae mariculture, coral reefs, euphotic zones, and water column). Among the four seas, the Bohai Sea and South China Sea are acting as CO_2 sources, releasing about0.22 and 13.86–33.60 Tg C yr~(-1) into the atmosphere, respectively, whereas the Yellow Sea and East China Sea are acting as carbon sinks, absorbing about 1.15 and 6.92–23.30 Tg C yr~(-1) of atmospheric CO_2, respectively. Overall, if only the CO_2 exchange at the sea-air interface is considered, the Chinese marginal seas appear to be a source of atmospheric CO_2, with a net release of 6.01–9.33 Tg C yr~(-1), mainly from the inputs of rivers and adjacent oceans. The riverine dissolved inorganic carbon (DIC) input into the Bohai Sea and Yellow Sea, East China Sea, and South China Sea are 5.04, 14.60, and 40.14 Tg C yr~(-1),respectively. The DIC input from adjacent oceans is as high as 144.81 Tg C yr~(-1), significantly exceeding the carbon released from the seas to the atmosphere. In terms of output, the depositional fluxes of organic carbon in the Bohai Sea, Yellow Sea, East China Sea, and South China Sea are 2.00, 3.60, 7.40, and 5.92 Tg C yr~(-1), respectively. The fluxes of organic carbon from the East China Sea and South China Sea to the adjacent oceans are 15.25–36.70 and 43.93 Tg C yr~(-1), respectively. The annual carbon storage of mangroves, wetlands, and seagrass in Chinese coastal waters is 0.36–1.75 Tg C yr~(-1), with a dissolved organic carbon(DOC) output from seagrass beds of up to 0.59 Tg C yr~(-1). Removable organic carbon flux by Chinese macroalgae mariculture account for 0.68 Tg C yr~(-1) and the associated POC depositional and DOC releasing fluxes are 0.14 and 0.82 Tg C yr~(-1), respectively. Thus, in total, the annual output of organic carbon, which is mainly DOC, in the China Seas is 81.72–104.56 Tg C yr~(-1). The DOC efflux from the East China Sea to the adjacent oceans is 15.00–35.00 Tg C yr~(-1). The DOC efflux from the South China Sea is 31.39 Tg C yr~(-1). Although the marginal China Seas seem to be a source of atmospheric CO_2 based on the CO_2 flux at the sea-air interface, the combined effects of the riverine input in the area, oceanic input, depositional export,and microbial carbon pump(DOC conversion and output) indicate that the China Seas represent an important carbon storage area.  相似文献   
65.
沈莎莎  陈爽  高群  张殷俊 《湖泊科学》2013,25(2):309-316
江苏省环太湖地区快速城市化和工业化加剧饮用水危机,整合研究水源地、供水、用水、排污处理和技术5个方面对于支撑该地区可持续发展的适应能力,对揭示饮用水供需关系、存在问题、部门协调与综合决策等具有现实意义.本文以构建5个子系统适应能力指标体系为主线,通过分指数与综合指数评价的运算,得出研究地区饮用水系统适应能力等级水平、地域分异特征及影响因素分析;针对各子系统存在问题,提出维护和提升适应能力的对策措施.研究表明,适应能力较强的地区占总面积29.1%,其5个子系统适应能力均较强.适应能力中等地区占41.2%,一类是各子系统适应能力基本均等,另一类是排污处理子系统适应能力较强,但用水子系统得分较低.适应能力较差地区占29.7%,主要是技术子系统分值低,其它子系统适应能力处于中等偏下.因此需加大对各子系统适应能力的调控与提升.  相似文献   
66.
In this paper, statistics are taken on the co-seismic response of underground fluid in Yunnan to the Nepal MS8.1 earthquake, and the co-seismic response characteristics of the water level and water temperature are analyzed and summarized with the digital data. The results show that the Nepal MS8.1 earthquake had greater impact on the Yunnan region, and the macro and micro dynamics of fluids showed significant co-seismic response. The earthquake recording capacity of water level and temperature measurement is significantly higher than that of water radon and water quality to this large earthquake; the maximum amplitude and duration of co-seismic response of water level and water temperature vary greatly in different wells. The changing forms are dominated by fluctuation and step rise in water level, and a rising or falling restoration in water temperature. From the records of the main shock and the maximum strong aftershock,we can see that the greater magnitude of earthquake, the higher ratio of the occurrence of co-seismic response, and in the same well, the larger the response amplitude, as well as the longer the duration. The amplitude and duration of co-seismic response recorded by different instruments in a same well are different.Water temperature co-seismic response almost occurred in wells with water level response, indicating that the well water level and water temperature are closely related in co-seismic response, and the well water temperature seismic response was caused mainly by well water level seismic response.  相似文献   
67.
Groundwater elevation fluctuation has been recognized as one mechanism causing temporal indoor air volatile organic chemical (VOC) impacts in vapor intrusion risk assessment guidance. For dissolved VOC sources, groundwater table fluctuation shortens/lengthens the transport pathway, and delivers dissolved contaminants to soils that are alternating between water saturated and variably saturated conditions, thereby enhancing volatilization potential. To date, this mechanism has not been assessed with field data, but enhanced VOC emission flux has been observed in lab-scale and modeling studies. This work evaluates the impact of groundwater elevation changes on VOC emission flux from a dissolved VOC plume into a house, supplemented with modeling results for cyclic groundwater elevation changes. Indoor air concentrations, air exchange rates, and depth to groundwater (DTW) were collected at the study house during an 86-d constant building underpressurization test. These data were used to calculate changes in trichloroethylene (TCE) emission flux to indoor air, during a period when DTW varied daily and seasonally from about 3.1 to 3.4 m below the building foundation (BF). Overall, TCE flux to indoor air varied by about 50% of the average, without any clear correlation to changes in DTW or its change rate. To complement the field study, TCE surface emission fluxes were simulated using a one-dimensional model (HYDRUS 1D) for conditions similar to the field site. Simulation results showed time-averaged surface TCE fluxes for cyclic water-table elevations were greater than for stationary water-table conditions at an equivalent time-averaged water-table position. The magnitudes of temporal TCE emission flux changes were generally less than 50% of the time-averaged flux, consistent with the field site observations. Simulation results also suggested that TCE emission flux changes due to groundwater fluctuation are likely to be significant at sites with shallow groundwater (e.g., < 0.5 m BF) and permeable soil types (e.g., sand).  相似文献   
68.
成熟盆地仍然蕴藏着可观的油气资源,目前的油气成藏理论面临越来越难、复杂、隐蔽油气藏勘探的挑战。受“链”事物属性的启发,通过调研、类比国内外油气成藏过程与分布规律,在继承和发展已有油气成藏理论基础上,结合勘探实践,学界提出了“油气聚集链”的概念和认识。油气聚集链指在成因上有密切联系、空间上多呈串珠状链式排列在一起的一系列油气藏组合,是油气成藏与分布本质规律的客观体现。油气聚集链在形式上多表现为油气藏多呈串珠状的链式空间分布特征,实质上表现为油气生成、运移、聚集的沿优势运移通道的链式反应和成藏事件;现今复杂的油气分布是地史上多条油气聚集链叠合的反映;一条完整的油气聚集链由内链、中链和外链组成,它们在成藏背景、成藏条件、成藏机理、富集规律和分布模式上既各有特征,又有连续性,更是紧密有机的油气生运聚成藏整体。“同源多链、一链多藏、多链成域、主链富集”是“油气聚集链”的四大特征。与目前油气成藏理论相比,油气聚集链认识的突出优势在于:发现和论证了油气聚集的链式成藏特点和多呈串珠状链式分布规律,提出沿“油气聚集链”寻找油气藏,比沿“油气聚集带”寻找油气藏的效率更高;将勘探目标的预测精度从油气聚集区带范围提高到某个具体圈闭或甜点。油气聚集链认识具有目前其他油气成藏理论所不具有的独特优势——链式思维,精准定位。依据油气聚集链的认识,提出了“找准链源,梳理链节,确定链环,重视主链”和“全链思维、整体研究,顺链找油、精准勘探”的思路,对指导成熟盆地继续挖掘勘探潜力、新区新领域获得勘探突破,都具有重要现实意义。以油气聚集链的认识为指导,转变勘探思维,在冀中、黄骅坳陷油气勘探中获得重大突破。  相似文献   
69.
塔里木北部地区三叠系储层在成岩演化过程中曾经历两期溶蚀作用,深埋成岩环境的晚期溶蚀较早期近地表-浅埋成岩环境溶蚀要剧烈得多,溶蚀作用的最大特点是铝硅酸盐矿物较碳酸盐矿物剧烈。溶蚀作用发生的机理是由于三叠系储层处于80~120℃热窗、成岩流体富含低分子量羧酸、碱度由低分子量羧酸控制,铝硅酸盐和碳酸盐矿物均处于去稳定状态。溶蚀作用的发育程度受控于储层砂体的沉积和岩石学特征以及早期成岩发育程度。  相似文献   
70.
帕米尔东北缘乌泊尔地区是正确认识帕米尔北缘盆山结构和构造变形特征非常关键的地区,本文利用连续电磁剖面(CEMP)资料和地震资料,并结合野外地质调查资料和钻井资料,对帕米尔东北缘乌泊尔地区的盆山结构和构造变形特征进行了研究。认为帕米尔东北缘及其以北地区的盆山结构表现为帕米尔造山带向北冲断和南天山向南冲断所形成的对冲结构; 帕米尔山前为基底卷入式构造,古生界—中生界沿高角度的逆冲断层推覆到新近系和第四系之上,形成山前的古生界—中生界逆冲推覆带; 北侧由受乌泊尔断裂控制的深部隐伏冲断体系和浅部的第四纪背驮盆地所构成。研究区的新生代构造变形时间开始于上新世晚期,并持续变形至今,形成了下更新统西域组(Q1x)与下伏上新统、Q2与Q1和Q3 4与Q2之间的不整合。研究区最小构造缩短量为486 km,缩短率为481%。  相似文献   
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