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61.
山西省万家寨引黄工程管理局信息系统初步建成,网络安全采用了防火墙、防病毒系统、入侵检测、信息加密、漏洞扫描等防范措施,但仍然存在诸多网络安全的隐患。通过建立物理隔离系统、拨号监控系统,完善防火墙、防杀病毒系统、入侵检测系统、漏洞扫描系统.引黄工程信息系统将成为全方位的安全体系,整个网络将畅通无阻,为引黄工程的生产及办公提供方便快捷的服务。 相似文献
62.
新疆塔里木河湿地保护和建设的研究 总被引:2,自引:0,他引:2
新疆塔里木河湿地是我国最长的内陆河流湿地,是多种鸟类栖息与多种候鸟迁徙中转、繁殖的重要区域.本文对塔里木河湿地的基本特征、生态功能、近代变化和其保护与建设的现实意义进行了研究,指出应该重视科学研究,拯救珍稀濒危物种,并提出了相应对策. 相似文献
63.
Differences between dynamics factors for interannual and decadal variations of rainfall over the Yangtze River valley during flood seasons 总被引:4,自引:0,他引:4
PING Fan LUO Zhexian JU Jianhua 《科学通报(英文版)》2006,51(8):994-999
The prediction of rainfall in the Yangtze River valley, especially, during flood seasons is the main means for scientists in China working on and the understanding of rainfall-associated processes is a crucial component of this effort. It can be derived f… 相似文献
64.
SHRIMP zircon U-Pb dating for volcanic rocks of the Dasi Formation in southeast Hubei Province, middle-lower reaches of the Yangtze River and its implications 总被引:13,自引:0,他引:13
Guiqing Xie Jingwen Mao Ruiling Li Shaodong Zhou Huishou Ye Quanren Yan Zusong Zhang 《科学通报(英文版)》2006,51(24):3000-3009
The Jinniu Basin in southeast Hubei,located at the westernmost part of middle-lower val-ley of the Yangtze River,is one of the important vol-canic basins in East China. Volcanic rocks in the Jin-niu Basin are distributed mainly in the Majiashan Formation,the Lingxiang Formation and the Dasi Formation,consisting of rhyolite,basalt and basaltic andesite,(trachy)-basalt and basaltic trachy-andesite and (trachy)-andesite and (trachy)-dacite and rhyolite respectively,in which the Dasi volcanism is volumet-rically dominant and widespread. The Dasi volcanic rocks were selected for SHRIMP zircon U-Pb dating to confirm the timing of volcanism. The results indi-cate that there exist a large amount of magmatic zir-cons characterized by high U and Th contents in the volcanic rocks. The concordia ages for 13 points are 128 ± 1Ma (MSWD = 3.0). On account of the shape of zircons and Th/U ratios,this age is considered to represent the crystallization time of the Dasi volcan-ism. The volcanic rocks in the Dasi,Majiashan and Lingxiang Formations share similar trace elementand REE partition patterns as well as Sr-Nd isotopic compositions. In combination with the regional geol-ogy,it is proposed that the southeast Hubei volcanic rocks were formed mainly during the Early Creta-ceous,just like other volcanic basins in middle-lower Yangtze valley. A lithospheric extension is also sug-gested for tectonic regime in this region in the Cre-taceous Period. 相似文献
65.
FU Kaidao HE Daming LI Shaojuan 《科学通报(英文版)》2006,51(B11):119-126
The impact of hydropower cascades of the Lancang River on downstream sedimentation has become one of the key problems in the research of the transboundary water resource development and its possible environmental effects. In this paper, the newest sediment data series spanning 17 years (1987-2003) at Yunjinghong hydrometric station and Chiang Saen hydrometric station, in northern Thailand, are analyzed to reveal these effects. Monthly mean sediment concentration data of the two stations are compared in-phase and yearly series are analyzed by the method of correlation and regression analysis and causality test. The analysis result shows that, though both of them are located at lower reaches of Manwan and Dachaoshan hydropower stations which are already constructed and in use, the sediment responses of the two stations are different under the regulation of the hydropower stations Annual series at Yunjinghong station are positively correlated but do not match well with those at Chiang Saen station. In addition, the results of Granger causality test on the time series also suggest that the series of maximum monthly mean sediment concentration of the Yunjinghong station each year may give cause for the ones of Chiang Saen station, while the series of minimum monthly mean sediment concentration each year and annual mean sediment concentration of Yunjinghong do not evidently give cause for the ones of the other station. Undoubtedly, this discovery will provide new evidences to assess the impacts of cascades construction in mainstream of the Lancang River on the variation of downstream sediment and its transboundary effects. 相似文献
66.
岷江上游干旱河谷区土壤水分含量及其动态 总被引:5,自引:0,他引:5
于2002年8月~2003年7月对四川西部理县干旱河谷区土壤水分状况进行了定位研究。结果表明:在理县干旱河谷区,不饲海拔高度0~50cm土层土壤平均含水量总的变化趋势是阴坡比阳坡高。而土壤水分空间异质性阳坡比阴坡大。同一坡向不同海拔的土壤含水量变化为2050m处的最高,1850m处的次之,1450m处再次之,1650m处最少,表明了在干旱区河谷的两岸坡面上部土壤水分状况最好,在坡面下部靠近河流处次之,中下坡水分条件最差。相同海拔高度,不同坡向土壤含水量都表现为随着土层深度的增加土壤含水量增加的趋势,且30~50cm土层的土壤含水量最高。 相似文献
67.
南京长江第三大桥斜拉索的防腐系统研究 总被引:3,自引:0,他引:3
根据目前我国拉索型桥梁索结构的防腐体系均遭到不同程度破坏的现状,在对索结构防腐体系破坏原因分析的基础上,结合南京长江第三大桥的特点,研究了拉索的防腐系统。结果表明:选择双峰HDPE护套,及在拉索内填充具有水汽隔绝、阻蚀防腐和润滑抗磨双重作用的防腐填充物,可延长拉索的使用寿命。该研究已成功应用于南京长江第三大桥的斜拉索体系。 相似文献
68.
The pericratonic sedimentary Jaisalmer Basin, west of the Aravalli Ranges, on the westerly dipping eastern flank of the Indus Shelf, is a principal structural element of Rajasthan. Jurassic sediments in the SE comprise non-marine sandstones and conglomerates to nearshore, brackish to marine sands, silts, clays and carbonates, grouped lithostratigraphically into the Lathi, Jaisalmer, Baisakhi, and Bhadasar formations. The Late Bajocian to Oxfordian Jaisalmer Formation is divided, in ascending order, into the Hamira, Joyan, Fort, Badabag, Kuldhar, and Jajiya members. Fossil records providing a Bajocian to Bathonian age for the lower and middle parts of the formation include: a Late Bajocian coral Isastraea bernardiana (d’Orbigny) in the uppermost Joyan Member; Bathonian ammonite Clydoniceras in the basal part of the Badabag Member; Bathonian foraminiferal/bivalve assemblages in the Fort Member. The topmost bed of the Joyan Member represents the peak of first marine transgression of the Jaisalmer Basin, probably contemporaneous with the Late Bajocian one in the neighbouring Kachchh Basin. Based on faunal studies Bajocian to Bathonian sediments of the Jaisalmer Basin can be broadly correlated with those of the Kachchh Basin. The Fort and Badabag members represent the following depositional environments, in chronological order: (a) brackish to shallow fully marine; (b) fully marine with rapidly fluctuating water energy and sedimentation rates; (c) near-shore to lower shoreface with fluctuating energy conditions, salinity and sedimentation rates; (d) near-shore to shoreface channels and storm-dominated marine above fair-weather wave-base; (e) lagoon with fluctuating low to moderate energy, salinity and sedimentation rates; (f) stormdominated shelf to lower shoreface. 相似文献
69.
针对受污染的黄河水源水,进行生物陶粒滤池试验研究.结果表明,生物陶粒滤池预处理能全面净化受污染黄河水的水质.在气水比为0.25:1、滤速为5.1m/h的条件下,对CODMn、NH 4-N、NO-2-N、的去除率分别为4.8%-22.7%,20%-77.6%,75%-98.3%.对UV254和藻类的去除率分别为7.3%-30.4%和24.4%-41.8%. 相似文献
70.
塔里木盆地古隆起的形成和油气控制 总被引:4,自引:0,他引:4
徐旭辉 《同济大学学报(自然科学版)》2004,32(4):461-465
塔北、巴楚和塔中隆起是塔里木盆地不同世代盆地原型结构复合的产物,对油气的分布起着重要的控制作用.其中,塔中、塔北隆起,为海西期油气运聚的主要指向区,具有良好的储盖条件,是油气重要的聚集场所.中新生代昆仑山崛起,塔西南挤榨前渊形成,致使克拉通内拗陷转化并反转形成巴楚隆起,与塔西南前渊迭加的古生代源岩构成统一的成藏系统. 相似文献