按比例实验室模型中孔身破裂的声波监控     

Raae.  AM  哓红 《物探化探译丛》1989,(6):34-37

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Migrating to learn and learning to migrate: a study of the experiences and intentions of international student migrants     

Li FL  Findlay AM  Jowett AJ  Skeldon R 《International journal of population geography : IJPG》1996,2(1):51-67

"The research reported here evaluates whether students come to the UK mainly for educational reasons, and therefore perceive their stay as temporary, or whether emigration for study is being used as part of a conscious strategy by people intending to become future labour migrants.... The simplest interpretation of the results appears to be that migration, experienced as a result of international moves for study purposes, does not influence planning of further migration moves. But the research also indicates that migration for education is closely tied to other types of population redistribution and should be treated by population geographers as an integral part of international migration systems." Data were collected by questionnaire survey from 349 engineering students at Hong Kong universities and 82 Hong Kong students studying engineering in the UK.  相似文献   

International retirement migration in Europe   总被引：2，自引：0，他引：2  

King R  Warnes AM  Williams AM 《International journal of population geography : IJPG》1998,4(2):91-111

"This paper presents a review and prospectus of international retirement migration (IRM), dealing mainly with European evidence but also referring to some analogous trends in North America. The paper is in three main parts. It first makes the case for regarding IRM as a significant aspect of population geography and of migration studies; in certain areas of Mediterranean Europe, IRM also has effects on regional economic geography. The second section of the paper discusses some of the early findings from a comparative study of British elderly residents in Tuscany, Malta, the Costa del Sol and the Algarve.... The final part of the article offers further reflections on why IRM is important--for the individual migrants themselves, for the host communities, and for public policy."  相似文献   

"An empire lost but a province gained": a cohort analysis of British international retirement in the Algarve     

Williams AM  Patterson G 《International journal of population geography : IJPG》1998,4(2):135-155

"The growth of international retirement in the Algarve has coincided with a number of changes in the international framework for population mobility as well as in the nature of the Algarve [Portugal] as a destination area. Tourism development, which is intimately linked to subsequent retirement migration, is particularly important in this. This paper considers the nature of the link between cycles of migration and of development in recipient areas, in the context of the remarkable and relatively late development of the Algarve as an area of tourism and retirement.... Cohort analysis...provides the basis for an examination of changes over time in the socio-demographic profiles of the migrants, their motivations, their residential patterns and their integration."  相似文献   

A sophisticated lander for scientific exploration of Mars: scientific objectives and implementation of the Mars-96 Small Station     

Linkin V  Harri AM  Lipatov A  Belostotskaja K  Derbunovich B  Ekonomov A  Khloustova L  Kremnev R  Makarov V  Martinov B  Nenarokov D  Prostov M  Pustovalov A  Shustko G  Jarvinen I  Kivilinna H  Korpela S  Kumpulainen K  Lehto A  Pellinen R  Pirjola R  Riihela P  Salminen A  Schmidt W  McKay CP 《Planetary and Space Science》1998,46(6-7):717-737

A mission to Mars including two Small Stations, two Penetrators and an Orbiter was launched at Baikonur, Kazakhstan, on 16 November 1996. This was called the Mars-96 mission. The Small Stations were expected to land in September 1997 (Ls approximately 178 degrees), nominally to Amazonis-Arcadia region on locations (33 N, 169.4 W) and (37.6 N, 161.9 W). The fourth stage of the Mars-96 launcher malfunctioned and hence the mission was lost. However, the state of the art concept of the Small Station can be applied to future Martian lander missions. Also, from the manufacturing and performance point of view, the Mars-96 Small Station could be built as such at low cost, and be fairly easily accommodated on almost any forthcoming Martian mission. This is primarily due to the very simple interface between the Small Station and the spacecraft. The Small Station is a sophisticated piece of equipment. With the total available power of approximately 400 mW the Station successfully supports an ambitious scientific program. The Station accommodates a panoramic camera, an alpha-proton-x-ray spectrometer, a seismometer, a magnetometer, an oxidant instrument, equipment for meteorological observations, and sensors for atmospheric measurement during the descent phase, including images taken by a descent phase camera. The total mass of the Small Station with payload on the Martian surface, including the airbags, is only 32 kg. Lander observations on the surface of Mars combined with data from Orbiter instruments will shed light on the contemporary Mars and its evolution. As in the Mars-96 mission, specific science goals could be exploration of the interior and surface of Mars, investigation of the structure and dynamics of the atmosphere, the role of water and other materials containing volatiles and in situ studies of the atmospheric boundary layer processes. To achieve the scientific goals of the mission the lander should carry a versatile set of instruments. The Small Station accommodates devices for atmospheric measurements, geophysical and geochemical studies of the Martian surface and interior, and cameras for descent phase and panoramic views. These instruments would be able to contribute remarkably to the process of solving some of the scientific puzzles of Mars.  相似文献   

Effects of sewage-impacted sediment on reproduction in the benthic crustacean Leptocheirus plumulosus     

Zulkosky AM  Ferguson PL  McElroy AE 《Marine environmental research》2002,54(3-5):615-619

Several organic contaminants in sewage effluent have been shown to elicit an estrogenic response in juvenile fish. Comparatively little emphasis has been placed on assessing these effects in marine invertebrates, particularly benthic organisms inhabiting sediment where lipophilic contaminants tend to persist. The present study examined reproductive effects in the benthic crustacean Leptocheirus plumulosus exposed to sewage-impacted sediment from Jamaica Bay, New York. Data from chronic 28-day tests showed a 50% reduction in the average number of young (juveniles + embryos) produced per surviving female in exposures to sediment from Jamaica Bay (JB). Nonylphenol ethoxylate ('NPEO) concentrations at this site were measured at 44.2 microg/g dw, concentrations two orders of magnitude higher than reference site concentrations in central Long Island Sound (CLIS). Dose-response studies with nonylphenol (NP) amended reference sediment, however, did not significantly affect reproduction suggesting that other contaminants may have contributed to the effects observed.  相似文献   

地质因素对珊瑚礁岩性状的影响     

Desh.  AM 陈亚平 《南海研究与开发》1993,(4):57-62

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Imposex and surface sediment speciation: a combined approach to evaluate organotin contamination in Guanabara Bay, Rio de Janeiro, Brazil     

Fernandez MA  de Luca Rebello Wagener A  Limaverde AM  Scofield AL  Pinheiro FM  Rodrigues E 《Marine environmental research》2005,59(5):435-452

An integrated biological-chemical survey of organotin compounds was carried out in Guanabara Bay, the second most important Brazilian harbor complex. The biological survey revealed high levels of imposex in Stramonita haemastoma populations. Inside the bay values of relative penis length index from 42.7 to 107.6 and vas deferens sequence index from III to VI were found, while organisms collected outside the bay had values ranging from <0.1 to 35.2 and from 0 to II. None of the females sampled inside the bay were normal and imposex was found in all stations. Surface sediments in the bay are contaminated by tributyltin (10-522 ng/g d.w.) and triphenyltin (<3.9-39.4 ng/g d.w.) with greater concentrations close to shipyards and marinas. The observed predominance of parent compounds (TBT and TPT) is commonly found when recent inputs occur, but may also indicate slow degradation processes in the anoxic conditions of these sediments. To our knowledge, this is the first report of a combined imposex-sediment approach to evaluate organotin contamination in marine environments of South America, and also the first report of TPT detection in environmental matrices in this region.  相似文献   

闪电定位密度数据泰森多边形优化方法     

冯真祯  张烨方  郑栋栋  张泉峰  杨超 《气象科技》2017,45(6):1011-1016

从识别、修订闪电定位监测数据异常值、提高闪电定位监测产品准确度的目的出发,以闪电定位栅格密度图为研究对象,结合人工观测雷电日数据及国内外对小电流幅值闪电数据剔除的研究成果,引入泰森多边形、数据分布假设检验、异常值(五数概括)处理算法等模型,建立了可用于判别和优化闪电定位监测数据栅格密度异常值的方法,以福建省为例,对该方法进行了实例应用。结果表明,在福建省西、北部区域,闪电定位监测数据存在一定探测误差或数据丢失的情况,并使用人工观测雷电日数据对这些异常值所在的区域进行了修订,该方法适用于闪电定位仪覆盖数量较少区域的闪电定位监测数据异常值识别与优化应用。  相似文献   

西藏多龙矿集区地堡Cu(Au)矿床含矿斑岩锆石U-Pb测年、Hf同位素组成及其地质意义   总被引：3，自引：0，他引：3  

林彬  陈毓川  唐菊兴  宋扬  王勤  冯军  李彦波  唐晓倩  林鑫  刘治博  王艺云  方向  杨超  杨欢欢  费凡  李力  高轲 《地质论评》2016,62(6):1565-1578

西藏多龙矿集区地堡铜(金)矿位于班公湖—怒江缝合带北侧,羌塘地块南缘,是多龙矿集区中具有较好找矿前景的斑岩—浅成低温热液矿床。本文首次对地堡含矿斑岩进行LA-ICP-MS锆石U-Pb测年、微量元素和Hf同位素分析。含矿斑岩23个锆石点测试,获得锆石~(206)Pb/~(238)U加权平均值年龄为122.0±2.5Ma(MSWD=0.34),与多龙矿集区成矿岩浆活动时限一致,是多龙矿集区的重要组成部分。锆石微量元素特征揭示地堡含矿斑岩中锆石为岩浆锆石,锆石Ti温度计计算出其结晶温度为663~850℃,平均为765℃,其岩浆源区可能经历了水饱和条件下的部分熔融作用。Hf同位素分析结果表明,地堡含矿斑岩锆石n(~(176)Hf)/n(~(177)Hf)值相对较高,为0.282726~0.283054,ε_(Hf)(t)为1.1~12.6,均为正值,其物质来源有幔源组分的加入,可能为壳幔混源的新生下地壳。  相似文献