Underwater Acoustic Communication Based on Pattern Time Delay Shift Coding Scheme   总被引：1，自引：0，他引：1  

殷敬伟  惠俊英惠娟姚直象  王逸林 《中国海洋工程》2006,20(3):499-508

1 .Introduction Underwater acoustic (UWA) communicationis a fast developingfield,and its applicationis notlimitedto military affairs ,but is also extendinginto commercial fields .Catipovic (1990) ,Stojanovic(1996) and Kilfoyle and Baggeroer (2000) pointed…  相似文献   

潮坪层序的粒度特征与沉积相划分--以杭州湾庵东浅滩为例   总被引：1，自引：0，他引：1  

郭艳霞  范代读  赵娟 《海洋地质前沿》2004,20(5):9-14

现代潮滩依据多年平均潮位线划分高、中、低潮滩，这对于古代潮坪沉积相研究无实际意义。本文尝试用潮坪层序粒度参数剖面来划分沉积相。潮坪沉积物以粉砂为主，但敏感地反映沉积动力变化的却是粗、细尾部分。因此，在沉积相划分时主要依据粘土、砂含量及平均粒径的变化特征。分选系数是一重要依据，但要考虑絮凝沉积的影响。偏态和峰态变幅小、较复杂，在相划分中只具参考价值。利用粒度参数剖面进行潮坪沉积相划分可广泛应用于古代潮坪层序研究，而且根据中潮坪沉积厚度(x)与平均潮差(y)存在的显著性相关关系：y=1．8314x 157．31(单位cm)，推算古潮差。  相似文献   

Effectiveness of the structural fisheries policy in the European Union     

Juan C. Surís-Regueiro  Manuel M. Varela-Lafuente  Carlos Iglesias-Malvido 《Marine Policy》2003,27(6):535-544

This paper presents an analysis of the effectiveness of the community structural policy in the fisheries sector by comparing the relative level of compliance with objectives (reduction of fleets and economic viability) with the mechanisms that have been implemented (structural funds and allocation of quotas). On the one hand, this analysis shows that there is a positive correlation between the level of structural funds and the attainment of goals. On the other hand, it was found that the greater the relative availability of quotas, the poorer the countries performed in complying with the objective of reducing the fishing capacity, and the higher the expectations of achieving acceptable yields. These correlations, however, were not very strong.  相似文献   

Diel variation in the vertical distribution and schooling behaviour of sardine (Sardina pilchardus) off Portugal     

Zwolinski  Juan; Morais  Alexandre; Marques  Vitor; Stratoudakis  Yorgos; Fernandes  Paul G. 《ICES Journal of Marine Science》2007,64(5):963-972

  相似文献   

Morphometric and gonad maturity in the spider crab Maja brachydactyla: a comparison of methods for estimating size at maturity in species with determinate growth     

Corgos  Antonio; Freire  Juan 《ICES Journal of Marine Science》2006,63(5):851-859

  相似文献   

Protected areas and coastal and ocean management in México     

Juan E. Bezaury-Creel   《Ocean & Coastal Management》2005,48(11-12):1016

No explicit “integrated coastal and ocean management” policy or program has been formally instituted to manage coastal and marine issues in México. Nevertheless two existing environmental policy tools: ecological zoning programs and coastal and marine protected areas, which have incorporated interagency and multi-stakeholder participation within their design, are currently being used in lieu of such strategy. Coastal and marine protected areas in México are the result of independent initiatives taken over the last 75 years and as a group cannot be characterized as the result of a systematic approach. Nevertheless México's 55 coastal and marine protected areas currently with a valid legal decree, occupy 11,791,824 ha which represents 69% of Mexico's total protected area surface. Only 46% of these include marine ecosystems with a total of 3,577,527 ha with the remaining 8,216,194 ha consisting of coastal ecosystems. (See In press update.)  相似文献   

地衣芽孢杆菌胞外产物消化活性的研究   总被引：12，自引：0，他引：12  

曹煜成  李卓佳  冯娟  陈永青  吴灶和 《热带海洋学报》2005,24(6):6-12

将地衣芽孢杆菌Bacillus licheniformis的胞外产物置于不同的pH、温度和金属离子条件下,分别测定其蛋白酶、淀粉酶、脂肪酶活性的变化。结果表明,当pH为7.5—8.5时胞外产物表现出较高的蛋白酶和淀粉酶活性,胞外产物消化脂肪的最适pH为9.0—10.0。胞外产物水解淀粉、脂肪和蛋白质最适温度分别为60—80、40—60和50—70℃,60℃时蛋白酶活力最大。试验测定了8种金属离子对胞外产物活性的影响,发现Mg2+、Zn2+Cu2+可抑制其水解蛋白质,而Ca2+、Fe3+、Mn2+和Ba2+却无此影响;在胞外产物消化脂肪底物时Co2+、Fe3+、Mn2+和Ba2+均能抑制其活力,而Mg2+、Zn2+能使其消化活力升高,与前者相比,金属离子对淀粉水解的影响相对较小,仅Cu2+有一定的抑制作用,其它离子对其均无明显的影响。还研究了不同胞外产物浓度与生物学活性的相关性,发现当反应体系中胞外产物浓度升高时水解蛋白质的活力会相应降低,但对脂肪的消化活力则与胞外产物的浓度呈正相关。反应体系中胞外产物的浓度在0—132.4μg.ml-1时其水解淀粉的活力随浓度的升高而升高,浓度为191.0μg.ml-1时活力最大,浓度大于191.0μg.ml-1时活力不再变化,稳定在一个较高的水平。  相似文献   

锌离子(Zn2+)对坛紫菜叶状体光合色素含量的影响     

郭新梅  戴继勋  王娟  徐矫健 《中国海洋大学学报(自然科学版)》2007,37(1):107-110

采用不同浓度Zn2 处理坛紫菜叶状体,用紫外分光光度法,测定了光合色素的含量。研究了金属Zn2 对坛紫菜叶状体中光合色素:叶绿素a、藻红蛋白、藻蓝蛋白和别藻蓝蛋白的影响。结果表明:Zn2 在0.5~5.0μmol/L时,有利于光合色素的合成;但在5μmol/L时,叶绿素a含量开始下降,在Zn2 浓度>10μmol/L时各光合色素含量也随浓度的升高而下降,对光合色素产生毒害作用。除去Zn2 后,都表现出向对照组恢复靠近的趋势,但别藻蓝蛋白的恢复较慢。  相似文献   

Cenozoic tectonics on the Galicia margin,northwest Spain     

Araceli?Mu?ozEmail author  Juan?Acosta  Elazar?Uchupi 《Geo-Marine Letters》2003,23(1):72-80

Neogene tectonic activity (Betic Orogeny) along the southern plate boundary of Iberia, as it converged with Africa and the Alboran Plate was inserted between them, propagated along Iberia's west side as far north as Galicia, northwest Spain. As the activity propagated northward, it reactivated structures formed during the Paleozoic (Hercynian), the Early Cretaceous opening of the northern North Atlantic and the Bay of Biscay, and the Paleogene Pyrenean Orogeny when Iberia collided with Eurasia. Recent earthquakes indicate that this tectonism is still active today as far north as northwest Spain.  相似文献   

鲍类微生物性疾病研究进展   总被引：4，自引：0，他引：4  

王瑞旋  徐力文  冯娟  王江勇 《海洋湖沼通报》2006,90(2):117-124

鲍类微生物性病害包括病毒性疾病、原核生物样疾病、细菌性疾病及真菌性疾病。本文就鲍类微生物病害的病原学、致病机制、组织病理学和流行病学等方面的进展,以及相关的诊断防治研究情况进行概述,以期为今后鲍类的病害防治研究提供依据。  相似文献