排序方式： 共有41条查询结果，搜索用时 31 毫秒
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中部Rajasthan地区的紫苏花岗岩主要呈“补片”状出露于早前寒武纪高级变质地体(一般称为条带状片麻杂岩或BGC)中。条带状片麻杂岩组成了印度次级大陆著名的Aravalli山脉基底的主体部分。以紫苏斜长花岗岩、石英紫苏闪长岩和紫苏闪长岩为代表的紫苏花岗岩类,与本区的科马提岩、变质苏长岩、方辉角闪岩、麻粒岩、花岗变晶岩、高级变质的泥质片岩、不纯石英岩、钙硅酸盐岩、花岗岩和混合岩等深就位岩石密切共生。清楚的侵入关系以反内部含有大量未吸收的变基性岩和片麻岩包体的存在,是紫苏花岗岩类的一个重要特征。紫苏花岗岩类具有坚硬、致密的特点,中粗粒,浅绿色至古铜色。这些特征与世界其它典型地区紫苏花岗岩相似,但本区紫苏花岗岩缺少层状、叶理、条带和与围岩渐变过渡等特征。 相似文献
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在兵库县南部地震前后观测到了震源区周围的地壳运动变化。地震等地壳运动与表层的地质情况密切相关。我们认为，支配这些活动的是地壳深部的断层运动及含水层的动态。 相似文献
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Turner RE Rabalais NN Swenson EM Kasprzak M Romaire T 《Marine environmental research》2005,59(1):65-77
An 18-year monitoring record (1978-1995) of dissolved oxygen within a region having hypoxia (dissolved oxygen less than 2 mgl(-1)) in the bottom layer was examined to describe seasonal and annual trends. The monitoring location was near or within a well-described summer hypoxic zone whose size has been up to 20,000 km(2). The monitoring data were used to hindcast the size of the hypoxic zone for before consistent shelfwide surveys started, and to predict it for 1989, when a complete shelfwide survey was not made. The concentration of total Kjeldahl nitrogen (TKN) in surface waters and concentration of bottom water oxygen were directly related, as anticipated if organic loading from surface to bottom was from in situ processes. The TKN data were used to develop a predictive relationship that suggested there was no substantial hypoxia before the 1970s, which was before nitrate flux from the Mississippi River to the Gulf of Mexico began to rise. The peak frequency in monthly hypoxic events is two to three months after both the spring maximum in discharge and nitrate loading of the Mississippi River. These results support the conclusion that persistent, large-sized summer hypoxia is a recently-developed phenomenon that began in the 1970s or early 1980s. 相似文献
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奥地利安东帕有限公司 《岩矿测试》2008,27(4):文后II-文后II
高压消解法测定钢铁中合金成分Digestion of Steel for the Accurate Determination of Alloying Constituents金属和合金中的组分通常采用火花源光谱仪直接测定。只要有合适的标准参考物质,采用这种技术可以在较短的时间内获得满意的测定结果;然而对于很多合金来说,由于没有合适的标准参考物质,必须利用综合分析技术。利用HPA—S高压消解仪对样品进行高压湿法消解和等离子体发射光谱法(ICP—OES)测定是一种通用和先进的方法,可以快速而准确地测定各种合金元素(如Cr、Ni、Ti、W、Mn、S和P),这种方法已经证明具有一定的可靠性。通过HP 相似文献
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于2009年对珠江口沿岸水域28个采样站位9种重金属元素的含量与分布进行了研究.使用原子吸收分光光度计分别测定了各采样站位沉积物中的Cu、Fe、Zn、Mn、Ni、Pb、Co、Cr和Cd的含量,并使用标准物作了质量控制.采用多种评价方法对不同环境重金属污染水平及潜在生态风险进行了评价.结果显示,珠江口沿岸水域表层沉积物中Cu、Fe、Zn、Mn、Ni、Pb、Co、Cr和Cd的平均含量分别为17.81 ～681.11、22 993.58 ～49 378.76、37.22 ～ 286.07、491.57 ～1 699.63、18.35 ～ 57.72、9.81 ～86.55、11.45 ～41.53、0.65 ～21.22、0.15 ～ 1.77 μg/g(干重).采用海洋沉积物质量标准法结合单因子污染指数法(Pi)评价显示,该海域已受到Cu和Cd污染,其含量均超海洋沉积物一类标准值.结合单元素生态危害因子(E(ri))和多元素潜在生态风险指数(RI)的评价显示,Cd和Cu已达到“重”和“严重”危害等级,其潜在生态风险属于“中度”等级.地质累积指数法(Igeo)评价则显示,Cu和Cd分别属“严重”和“中度”污染程度.综合评价表明,珠江口沿岸水域沉积物受Cu和Cd污染较严重,已对海洋环境和沿岸海水养殖造成严重的潜在危害.建议控制养殖区养殖密度,减少网箱数量和人类养殖活动. 相似文献
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Zhu Liping Institute of Geography CAS Beijing People''s Republic of ChinaW.B. Whalley Department of Geography The Queen''s University of Belfast BT NN UKWang Jiacheng Lanzhou Institute of Glaciology Geocryology CAS Lanzhou Pe 《地理学报(英文版)》1997,(4)
Ｉ.ＩｎｔｒｏｄｕｃｔｉｏｎＷｅａｔｈｅｒｉｎｇｂｅｈａｖｉｏｕｒｏｆｒｏｃｋｍｕｓｔｂｅｖｉｅｗｅｄａｓｂｅｉｎｇｔｈｅｒｅｓｕｌｔｏｆｉｎｔｅｒａｃｔｉｏｎｂｅｔｗｅｅｎｔｈｅｉｎｔｒｉｎｓｉｃｐｒｏｐｅｒｔｉｅｓａｎｄｅｘｔｅｒｎａｌｃｌｉｍａｔｉｃｃｏｎｄｉｔｉｏｎｓ[45].Ｍｏｓｔｒｅｆｅｒｅｎｃｅｓｔｏｆｒｏｓｔｓｈａｔｔｅｒｉｎｇｈａｖｅｅｍｐｈａｓｉｓｅｄｔｈｅｄｉｓｒｕｐｔｉｖｅｆｏｒｃｅｓａｓｓｏｃｉａｔｅｄｗｉｔｈｔｈｅｐｈａｓｅｃｈａｎｇｅｓｏｆｗａｔｅｒｔｏｉｃｅ[1,26,34,3… 相似文献
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微波消解法测定磷矿石中的主次量组分 总被引：1，自引：0，他引：1
奥地利安东帕有限公司 《岩矿测试》2007,26(6):512-512
磷元素是植物和动物营养的必需元素，所以全世界绝大多数的磷被作为一个主要成分用于粮食作物的氮-磷-钾肥料中。磷矿石是全球磷元素的最重要来源。 相似文献
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Perinereis aibuhitensis(Grube, 1878) lives in marine sediments of estuary or shoal areas, where substrate has some crucial environmental factors affecting its burrowing and distribution. In order to provide basic data for the habitat selection and suitability evaluations of the artificial aquaculture of P. aibuhitensis, this paper conducted a quantified analysis of its burrowing ability and explored its behavioral preferences in different substrates,including mud(75 μm), fine sand(125–250 μm), medium sand(250–500 μm), coarse sand(500–2 000 μm), gravel(2 000–4 000 μm) and ceramsite(4 000–8 000 μm). The research results revealed that substrate grain size significantly affected the burrowing time, burrowing rate, burrowing depth and distribution rate(P0.01).Moreover, P. aibuhitensis demonstrated preferential selections relating to substrate grain sizes, had higher burrowing ability in ceramsite, mud and fine sand compared with other substrates. The strongest burrowing ability and the highest distribution rate were observed in ceramsite. The study indicated that P. aibuhitensis was sensitive to substrate grain size, which also had an impact on its burrowing process and population distribution.In the natural sea, substrates mainly composed of mud and fine sand are fit for aquaculture and stock enhancement. Based on behavioral preferences and ecological rehabilitation function of P. aibuhitensis, this paper proposes a symbiotic system of marine animals and halophytes, and constructs an ecosystem model of"Marine fish-Halophytes-Perinereis aibuhitensis" with P. aibuhitensis as the link. 相似文献