在6厘米波长对类星体3C454.3的九站VLBI观测     

吴盛殷  I.Pauliny-Toth  R.Porcas  A.Zensus 《中国天文和天体物理学报》1986,(2)

3C454.3是近几年引起广泛注意的一个强活动射电类星体,它有毫角秒尺度的核——喷流结构,其核在1981年的一次流量密度大爆发之后,显示出“超光速增亮”现象,在6厘米波长,用包括欧洲、美国及南非的9个射电望远镜,于1983年10月对3C454.3进行了甚长基线干涉网观测。观测结果除了证实其核——喷流结构,显示了从毫角秒到角秒尺度上该类星体结构的系统弯曲外,还清楚地揭示了“超光速增亮”所预期的,在1981年8月到1983年1月期间,核的超光速膨胀现象。  相似文献   

用三辛基氧膦和联苯与萘的熔融混合物通过溶剂萃取...     

Kojima  I 刘建英 《国外铀金地质》1990,(3):82-85

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北极东部陆架沉积盆地与油气藏展望     

V.  E.  Khain  I.  D.  Polyakova  李学杰 《海洋地质》2008,24(3)

北极东部宽广的陆架展布着几个不同时期、不同走向的裂谷成因构造。利用构造纲要图，展示了上Brooksian地层单元（白垩纪-新生代）的主要构造元素，并勾画出Ellesmerian地层单元（晚泥盆世-侏罗纪）的构造轮廓，通常认为本区该期烃源岩最丰富。上地层单元发现了3个主要沉积盆地：Vil’kitskii-北楚科奇盆地，南楚科奇盆地和东楚科奇盆地，它们被楚科奇中央隆起所分隔。该隆起在EUesmerian期最活跃。通过与研究详细的陆架和陆坡区对比，概括了这3个盆地烃类的形成和聚集模式，了解可能的油气储集远景区带。  相似文献   

Survey of estrogenic and androgenic disruption in Swedish coastal waters by the analysis of bile fluid from perch and biomarkers in the three-spined stickleback   总被引：1，自引：0，他引：1  

Pettersson M  Hahlbeck E  Katsiadaki I  Asplund L  Bengtsson BE 《Marine pollution bulletin》2007,54(12):1868-1880

The potential for endocrine disruption close to sewage treatment plant and pulp mill effluent discharge points along the Swedish Baltic Sea coast was explored using a dual survey strategy employing two stationary fish species. The levels of vitellogenin and spiggin as biomarkers of endocrine disruption were determined in juvenile three-spined sticklebacks (Gasterosteus aculeatus L.) together with the sex ratios and the presence of intersex. As an indication of exposure, estrogenic and androgenic substances were analysed by GC–MS in bile from perch (Perca fluviatilis L.). Spiggin and vitellogenin levels in juvenile three-spined sticklebacks were generally low, and, for most sampling sites no deviation in gonad type ratios were observed. No remarkable levels of natural or synthetic estrogens or androgens were observed in bile fluid from perch, while bisphenol A and 4-nonylphenol were detected in perch from both reference sites and exposed sites. Taken together, the results did not indicate estrogenic or androgenic disruption in the investigated waters.  相似文献   

Beach tar accumulation, transport mechanisms, and sources of variability at Coal Oil Point, California     

Del Sontro TS  Leifer I  Luyendyk BP  Broitman BR 《Marine pollution bulletin》2007,54(9):1461-1471

A new field method for tar quantification was used at Coal Oil Point (COP), California to study the mechanisms transporting oil/tar from the nearby COP natural marine hydrocarbon seep field. This method segregates tar pieces into six size classes and assigns them an average mass based on laboratory or direct field measurements. Tar accumulation on the 19,927m(2) survey area was well resolved spatially by recording tar mass along twelve transects segmented into 4-m(2) blocks and then integrating over the survey area. A seasonal trend was apparent in total tar in which summer accumulations were an order of magnitude higher than winter accumulations. Based on multiple regression analyses between environmental data and tar accumulation, 34% of tar variability is explained by a combination of onshore advection via wind and low swell height inhibiting slick dispersion.  相似文献   

Air--sea gaseous exchange of PCB at the Venice lagoon (Italy)     

Manodori L  Gambaro A  Moret I  Capodaglio G  Cescon P 《Marine pollution bulletin》2007,54(10):1634-1644

Water bodies are important storage media for persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and this function is increased in coastal regions because their inputs are higher than those to the open sea. The air-water interface is extensively involved with the global cycling of PCBs because it is the place where they accumulate due to depositional processes and where they may be emitted by gaseous exchange. In this work the parallel collection of air, microlayer and sub-superficial water samples was performed in July 2005 at a site in the Venice lagoon to evaluate the summer gaseous flux of PCBs. The total concentration of PCBs (sum of 118 congeners) in air varies from 87 to 273 pg m(-3), whereas in the operationally defined dissolved phase of microlayer and sub-superficial water samples it varies from 159 to 391 pg L(-1). No significant enrichment of dissolved PCB into the microlayer has been observed, although a preferential accumulation of most hydrophobic congeners occurs. Due to this behaviour, we believe that the modified two-layer model was the most suitable approach for the evaluation of the flux at the air-sea interface, because it takes into account the influence of the microlayer. From its application it appears that PCB volatilize from the lagoon waters with a net flux varying from 58 to 195 ng m(-2)d(-1) (uncertainty: +/-50-64%) due to the strong influence of wind speed. This flux is greater than those reported in the literature for the atmospheric deposition and rivers input and reveals that PCB are actively emitted from the Venice lagoon in summer months.  相似文献   

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine,Middle Benue Trough,Nigeria     

Nganje T.N.  Adamu C.I.  Ukpong E.E. 《中国地球化学学报》2010,29(2):167-174

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOI) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (10%). Levels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leavescassava tuberspeelings. In the same plant species, metal levels decreased in the order of ZnFeMnCuPbCrCd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOI as some of the factors influencing soil-plant metal uptake.  相似文献   

太平洋海山富钴结壳钙质超微化石生物地层学及生长过程          下载免费PDF全文

张海生  韩正兵  雷吉江  赵军  于培松  胡佶  卢冰  Pulyaeva  I.A. 《地球科学》2014,39(7):775-783

正确判断富钴结壳生长年代及过程有助于研究结壳形成地质历史和重建古海洋环境.利用生物地层学方法(生物遗留印痕)对太平洋不同海山结壳样品进行生长时代和阶段研究,发现麦哲伦海山CM3D06结壳和中太平洋海山CB14结壳最初形成年代和富集特征差异显著: 前者为白垩纪(或更古老)、晚古新世-早始新世、中-晚始新世、中-晚中新世、上新世-更新世等5个阶段;后者为晚古新世-早始新世、中-晚始新世、中中新世、上新世-更新世等4个阶段.两座海山结壳层内部超微化石组合具有极强的区域性特征,反映了大洋环境对生物的影响以及生物对环境的适应.结壳层间的不整合和结构构造的变化指示在渐新世其生长存在间断期,与成矿作用的间断有关.   相似文献   

Stellar Population Analysis of Galaxies based on Genetic Algorithms     

Abdel-Fattah Attia  H. A. Ismail  I. M. Selim  A. M. Osman  I. A. Isaa  M. A. Marie  A. A. Shaker 《中国天文和天体物理学报》2005,5(4):347-355

We present a new method for determining the age and relative contribution of different stellar populations in galaxies based on the genetic algorithm. We apply this method to the barred spiral galaxy NGC 3384, using CCD images in U, B, V, R and I bands. This analysis indicates that the galaxy NGC 3384 is mainly inhabited by old stellar population (age >109yr). Some problems were encountered when numerical simulations are used for determining the contribution of different stellar populations in the integrated color of a galaxy. The results show that the proposed genetic algorithm can search efficiently through the very large space of the possible ages.  相似文献   

Nucleic acid     

Fig.　Agarose gel electrophoresis of WSSV nucleic acid. Line . λHind III DNA marker  Line . WSSV nucleic aciddigested with EcoR I  Line . Undigested WSSV nucleic acid 《中国海洋湖沼学报》2000,18(1):241-246