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排序方式: 共有2298条查询结果,搜索用时 26 毫秒
991.
根据浅层地震和钻孔资科,将澳大利亚东南部研究地区高能波控陆架风暴沉积分为直立风暴层、叠瓦状风暴层、无序风暴层、水平风暴层和纹层状风暴层等五类。各类风暴层及风暴层与非风暴层组合而成悬移风暴层序、悬移-推移混合风暴层序和推移风暴层序三大类。中陆架风暴沉积与现今近岸和水下岸坡相似,岩性、岩相和古生物属海岸带,风暴沉积厚,底板埋深大,组成物质粗。推断中陆架风暴沉积当形成于冰后期海侵、该地带处在近岸带和水下岸坡环境时,此时海面上升速度可能减缓,或趋近于零,甚至可能有短时间的下降。 相似文献
992.
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
993.
Larkin P Folmar LC Hemmer MJ Poston AJ Lee HS Denslow ND 《Marine environmental research》2002,54(3-5):395-399
A variety of anthropogenic chemicals are capable of binding to the estrogen receptor of vertebrate species. Binding of these compounds can interfere with homeostasis by disrupting normal gene expression patterns. The purpose of this study was to investigate the feasibility of applying array technology as a monitoring tool for detecting the presence and distribution of estrogenic compounds in coastal habitats using sheepshead minnows as our model. cDNA clones that were isolated from differential display, including vitellogenin alpha and beta, vitelline envelope protein (ZP2), and transferrin, among others, were spotted on the macroarray. The results of these experiments demonstrate a characteristic expression pattern of estrogen responsive genes in sheepshead minnows exposed to 17 beta-estradiol (E2). 相似文献
994.
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
995.
Effects of dietary exposure to the pyrethroid pesticide esfenvalerate on medaka (Oryzias latipes) 总被引:3,自引:0,他引:3
Werner I Geist J Okihiro M Rosenkranz P Hinton DE 《Marine environmental research》2002,54(3-5):609-614
The pyrethroid insecticide esfenvalerate is widely used on orchard crops throughout California. In the aquatic environment, this compound is likely to accumulate in sediments, food particles and benthic organisms due to its lipophilicity and environmental persistence. This pilot project tested the hypothesis that esfenvalerate is toxic to medaka (Oryzias latipes) when taken up with the diet. For 7 days fish were fed diets, which contained esfenvalerate in three different concentrations (4, 21, 148 mg/kg, measured). Endpoints measured were mortality, fecundity, fertilization and hatching success of embryos, viability of larvae and cellular stress protein (hsp60, hsp70, hsp90) levels. The toxicity of aqueous exposure of medaka to esfenvalerate was also determined. Whereas the 96-h LC50 in the aqueous exposure was <9.4 microg/l, the dietary exposure did not cause mortality. Possible effects of dietary esfenvalerate were seen on fertilization and hatching success and the number of non-viable larvae. Expression of hsp60 and hsp90 showed a dose-dependent response pattern. 相似文献
996.
997.
从分离测定海水样品中稀土元素的经典工作开始,确定海水中稀土元素分布图便成为一个实际难题.由于稀土元素的浓度在pmolkg^-1范围,需要预富集或采用先进的分析仪器.作为预富集技术曾成功地运用过Fe(OH)3共沉淀法,离子交换色谱和溶剂萃取等方法.对稀土元素的测定, 相似文献
998.
一、序言ENSO现象对全球大气环流及其伴随天气的影响,一直是近年来海气相互作用研究的焦点之一,一些有趣的研究表明,ENSO现象对中纬度气候有显著的影响.本文统计了1899-1962年每年发生在20°-40°N,120°-150°E区域(图1)以及主要气旋活动中心(图1阴影 相似文献
999.
During the summer of 1930 we had. thanks to the Central Asiatic Expedition led by Dr. R.C. Andrews, a splendid opportunity for studying the geological formations of SE. Gobi, along the Kalgan-Urga trail, South and 相似文献
1000.