冲绳海槽晚更新世以来古海洋学的研究   总被引：8，自引：1，他引：8  

阎军  P.R.Thompson 《海洋与湖沼》1991,22(3):264-271

冲绳海槽Z_(14-6)孔柱状样于1981年取得,该孔浮游有孔虫系统鉴定、统计及转换函数分析表明,该区12万年来曾存在三个温暖时期,末次间冰期存在两次寒冷波动。氧同位素5e亚期为最温暖时期,海水冬季表层水温高出现代1.9℃;氧同位素第2期为本区晚更新世以来最寒冷时期,冬季海水表层水温降至12.4℃,比现今低6.8℃。海水冬、夏表层水温差异与气候的寒冷程度有关,气候越寒冷,温差越大。此外,本文还就黑潮的某些古海洋学特性进行了初步探讨。  相似文献   

Expression and activity of a multixenobiotic resistance system in the Pacific oyster Crassostrea gigas     

Minier C  Lelong C  Djemel N  Rodet F  Tutundjian R  Favrel P  Mathieu M  Leboulenger F 《Marine environmental research》2002,54(3-5):455-459

The multidrug resistance (MDR) mechanism corresponds to a defence system relying on the expression of high molecular membrane proteins that can actively lower the intracellular concentration of a wide variety of toxins, thus maintaining them below their toxic level. Using RT-PCR, expression levels of a gene belonging to the class I of mammalian mdr genes, has been assessed in different developmental stages of the oyster Crassostrea gigas. While no expression was found in the oocyte or the trocophore stage, a rise of mRNA content was observed from the veliger stage to the juvenile stage, thus indicating the induction of the system as the animal is developing in the environment. The incubation of gill fragments in the dye rhodamine B and subsequent measurements of intracellular fluorescence using a microplate reader indicates that the system can effectively decrease the accumulation of the test compound in a competitive manner with known inhibitors or environmental contaminants as observed in vertebrate cells. The oyster MXR system is thus becoming active in adult oyster and could be of importance in environmentally contaminated areas.  相似文献   

The role of biological research in supporting policy needs     

Leonard P 《Marine environmental research》2002,54(3-5):209-213

Within the UK, the Department for Environment, Food and Rural Affairs (DEFRA) is one of several government departments which undertakes research in support of its policy aims. For example, DEFRA has responsibility for licensing the deposit of materials in the sea in order to protect the environment, public health and prevent interference with other uses of the sea. This includes assessment of pollutant responses in marine organisms. The objectives include assessment of the sub-lethal effect that pollutants have at the cellular, organ and individual level, for example in normal genetic, behavioural and reproductive activity and extrapolation of the potential impact of pollutants to populations. This work helps DEFRA to establish whether individually or in combination, pollutants have an adverse effect on the environment. This paper gives some examples of the research undertaken and demonstrates how biological research can provide cost effective solutions to analytical problems and an opportunity to predict the way in which proposed disposal operations may have an impact on the marine environment. The way such research may influence policy is also discussed.  相似文献   

用TRXRF分析法测试马来西亚微咸水中双壳类软体动物Geloina ceylonica(Lamarck)中的重金属     

P.M.Sivalingam 《海洋科学》1984,8(2):37-40

马来西亚有近2.4%的陆地面积(相当于650,000公顷)是红树林沼泽区。其中,110,000公顷在马来西亚半岛,174,000公顷在沙捞越,366,000公顷在马来西亚的沙巴。当前对于马来西亚红树林沼泽区的生态研究还寥寥无几(Sase Kumar,1970;Ong等人,1979)。对植物区系和动物区系的研究显然也是如此(Berry,1968,1972和1974;Lim,  相似文献   

A line survey of Orion KL from 325 to 360 GHz     

Schilke P  Groesbeck TD  Blake GA  Phillips TG 《The Astrophysical journal. Supplement series》1997,108(1):301-337

We present a high-sensitivity spectral line survey of the high-mass star-forming region Orion KL in the 325-360 GHz frequency band. The survey was conducted at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii. The sensitivity achieved is typically 0.1-0.5 K and is limited mostly by the sideband separation method utilized. We find 717 resolvable features consisting of 1004 lines, among which 60 are unidentified. The identified lines are due to 34 species and various isotopomers. Most of the unidentified lines are weak, and many of them most likely due to isotopomers or vibrationally or torsionally excited states of known species with unknown line frequencies, but a few reach the 2-5 K level. No new species have been identified, but we were able to strengthen evidence for the identification of ethanol in Orion and found the first nitrogen sulfide line in this source. The molecule dominating the integrated line emission is S02, which emits twice the intensity of CO, followed by SO, which is only slightly stronger than CO. In contrast, the largest number of lines is emitted from heavy organic rotors like HCOOCH3, CH3CH2CN, and CH3OCH3, but their contribution to the total flux is unimportant. CH3OH is also very prominent, both in the number of lines and in integrated flux. An interesting detail of this survey is the first detection of vibrationally excited HCN in the v2 = 2 state, 2000 K above ground. Clearly this is a glimpse into the very inner part of the Orion hot core.  相似文献   

A multi-level perspective on small-area health and mortality: a case study of England and Wales     

Congdon P  Shouls S  Curtis S 《International journal of population geography : IJPG》1997,3(3):243-263

"This paper considers morbidity and mortality variations at the small-area level in England and Wales and their relation to socio-economic factors. Separate affluence and deprivation effects on illness and mortality are identified from a single-level analysis, both exceeding the influence of social class, urbanity or ethnicity. A multi-level perspective is then adopted to explore ecological associations operating both at micro-area and higher level spatial scales. Contextual effects (higher level variability in the impacts of ward level variables) are identified in the effects of small area deprivation on mortality and illness, as well as cross-level interactions; thus the impact of small area social structure on health is partly defined by the wider regional and district setting."  相似文献   

The selection of internal migration models for European regions     

Van Imhoff E  Van Der Gaag N  Van Wissen L  Rees P 《International journal of population geography : IJPG》1997,3(2):137-159

"A full multiregional projection model requires migration data that are simultaneously classified by age and gender and region of origin and region of destination. Except for a very small number of regions, these data requirements are so high that aggregation of the data (which is equivalent to simplification of the model) is called for. This paper investigates the extent to which the full internal migration matrix can be simplified without seriously affecting the performance of the resulting multiregional model. Using IPF (iterative proportional fitting) methods, a log-linear analysis of alternative model specifications is made, using data for Italy, the Netherlands and the UK....A reasonable balance between goodness-of-fit and parsimony is found for the model in which time interacts with the main effects only (i.e. with age/sex, with origin and with destination)."  相似文献   

Geology Along the Line from Yecheng to Shiquanhe and Tectonic Evolution of the Region Involved   总被引：4，自引：0，他引：4  

Ph.Matte  P.Tapponnier 《《地质学报》英文版》1995,69(2)

The geotraverse from Yecheng to Shiquanhe, on the western Qinghai-Tibet Plateau, totalling 1056 km in length, passes the western Kunlun Mountains and the eastern end of the Karakorum Mountains. The Chinese and French scientists made a joint investigation along the line from July to August, 1989. Based on the outcropped ophiolites, palaeontology, sedimentary facies, magmatism, tectonic deformation and metamorphism, the region involved may be divided from north to south into five terranes and four ophiolitic suture zones. The ages of these terranes have a tendency to become increasingly younger from north to south.  相似文献   

Immigration--mismatches in labour,housing and space: the effects of immigration of several nationalities with regard to the Netherlands     

Musterd S  Muus P 《Applied geography (Sevenoaks, England)》1995,15(3):279-296

"In the Netherlands, the sharp recent increase of the number of refugee immigrants (asylum seekers) runs parallel to increased numbers of immigrants of other types. Therefore, at least five types of immigrants should still be distinguished (labour migrants, migrants from former colonies, from EU countries, from other rich countries, and asylum seekers). Their spatial orientation in the Netherlands (urban, suburban, rural), by choice or by constraint, is the main focus of this study. The outcomes of the immigration processes have been confronted with general and spatial characteristics of the labour market and housing market. Matches and mismatches are discussed."  相似文献   

Public housing as a barrier to long-distance migration     

Boyle P 《International journal of population geography : IJPG》1995,1(2):147-164

The relationship between migration and housing tenure in Britain is explored, with particular reference to those living in subsidized housing provided by local councils. "In this study, data have been extracted from the 1991 Sample of Anonymised Records to assess the impacts of tenure on long-distance migration compared with short-distance migration. Logit models are used to control for the effects of a wide range of socio-economic variables, allowing the independent impact of tenure to be identified. It is shown that long-distance migrants are less likely to move into council housing than other tenures, but it is argued that this does not support the assumption that the sale of council housing will necessarily increase labour mobility."  相似文献