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1.
渤海主要生物种间关系及食物网的研究   总被引:24,自引:4,他引:20  
根据1992年-1993年渤海增殖生态基础调查大面定点底拖网试捕的渔获物,对渤海27种鱼类和10种虾蟹类的3801个胃含物样品进行了分析,并与10年前渤海鱼类的食性进行了比较。结果表明:蓝点马鲛、小黄鱼和白姑鱼等主要捕食鱼类胃含物中鱼的比例较10年前明显增加,鱼类的食性类型无明显变化。渤海低级肉食性鱼类的营养级由1982-1983年的平均2.4上升为2.5,中、高级肉食性鱼类的营养级分别由原来的平均3.2和3.8降为2.8和3.3。渤海主要鱼类之间饵料重叠系数大于0.6的占15%。鱼为渤海多数中、高级肉食性鱼类的主要摄食对象。  相似文献
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桑沟湾贝类筏式养殖与环境相互作用研究   总被引:10,自引:0,他引:10  
2003年6~10月和2004年3月利用YSI6600多参数水质监测仪和SD6000全自动海流计以及石膏块对桑沟湾扇贝筏式养殖区养殖设施内外、扇贝养殖笼内外部分环境参数(pH、DO、叶绿素a、海流)的动态变化进行了系统研究。实验结果表明:(1)扇贝筏式养殖区内外流速及叶绿素a浓度衰减显著:经过20排筏架(约105m)后,养殖区内的海水平均流速由区外的7·50±5·29降到5·28±3·23cm·s~(-1),降低了29·6%,区内外海流的主流向没有显著改变;进入养殖系统的叶绿素a浓度由2·48降低到了1·19μg·L~(-1),减少了52%;养殖区内的pH和溶解氧与区外相比变化不大;(2)扇贝养殖笼内外环境因子发生显著的变化:2003年7月1日养殖笼内外水交换率可达80·5%,1个月后下降到只有23·6%;2004年10月份养殖笼内叶绿素a浓度降低到仅有1·57μg·L~(-1),较之笼外的4·20μg·L~(-1)来说,减少了62·6%;养殖笼外pH基本保持在8·0左右,笼内的pH却一直趋于下降趋势,到9月份降到了最低值7·46;在附着生物附着盛期的8、9月份,笼内溶解氧最低值降低到了5·13mg·L~(-1),比起笼外的7·04mg·L~(-1)来说,减少了27·1%。  相似文献
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中国沿海两例食用织纹螺中毒事件中织纹螺体内毒素分析   总被引:9,自引:0,他引:9  
近年来,因食用织纹螺(Nassariusspp.)导致的中毒事件在中国沿海屡有发生。由于中毒患者的症状与麻痹性贝毒中毒症状相似,因此,许多中毒事件被归咎于麻痹性贝毒,认为织纹螺中的毒素与邻近海域的有毒赤潮有关,但也有研究发现螺体内存在河豚毒素。对此,本研究应用亲水性相互作用色谱柱建立了河豚毒素的液相色谱-质谱联用分析方法,对造成2002年和2003年两次中毒事件的织纹螺样品进行分析。结果表明,两批织纹螺样品中均含有高浓度的河豚毒素及其衍生物,包括三脱氧河豚毒素、脱水河豚毒素和单加氧河豚毒素等,而且两个织纹螺样品中的毒素组成非常相似。因此,导致这两起中毒事件的致毒因子是河豚毒素及其衍生物。江苏和福建两地织纹螺中毒素组成的相似性显示两地织纹螺可能具有相同或相近的毒素来源。  相似文献
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Abstract– A few native and exotic fish species are caught frequently in Andean lakes and reservoirs of northwestern Patagonia. Puyen ( Galaxias maculatus ) prey on zooplankton and benthos. Percichthys trucha has a wide range of prey, mainly benthos, while P. colhuapiensis become piscivorous when grown. Pejerrey ( Odonthestes hatcheri ) is omnivorous and large size individuals can be piscivorous. A siluroid, Diplomystes viedmensis , preys on benthos, insects, and fishes. Introduced salmonids are potential piscivorous. The puyen is the major prey category among fishes. Salmonids and perchichtids seem to partially overlap their diets but predation on Diplomystes appears to be restricted to salmonids. Present abundance of puyen, pejerrey and Percichthys spp. does not indicate a strong salmonid effect. However, the low abundance of D. viedmensis does. We studied present predation relationships among native and introduced fishes and postulated possible effects upon native fish fauna.  相似文献
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Abstract –  We studied the impact of two exotic salmonid species (brook trout, Salvelinus fontinalis and rainbow trout, Oncorhynchus mykiss ) on native brown trout ( Salmo trutta fario ) habitat, growth and survival. Habitat selection and vertical distribution between young-of-the-year of the three species were examined in a stream aquarium under different sympatric and allopatric combinations. In addition, similar species combinations were introduced in a Pyrenean mountain stream (southwest France) in order to extend laboratory results to growth and apparent survival. Both laboratory and field results indicated that rainbow trout significantly affected native brown trout habitat selection and apparent survival. On the contrary, brown trout habitat, growth and apparent survival were hardly affected by brook trout. These results support the idea that rainbow trout negatively influence native brown trout, and that competition could influence the outcome of fish biological invasions in freshwater ecosystems.  相似文献
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依据凡纳滨对虾多性状复合育种方案,模拟选择20个世代,预测和评估了目标性状(收获体质量(BW),存活率(SR)和饲料摄入量(FI))的遗传进展及经济效益。利用选择指数理论,估计目标性状的选择反应、遗传进展以及育种目标;并对影响利润(RP)和效益成本比率(BCR)的生物学参数(遗传力、育种目标是否包括FI),经济学参数(对虾价格、饲料价格、贴现率、初投资、年费用)和运行参数(首次回报年份、扩繁效率)进行了敏感性分析。结果表明,在基础参数值下,BW、SR和FI每个世代的选择反应分别为0.86g,4.70%和1.54g;育种方案执行20年产生的RP和BCR分别为862747.91万元和844.26;敏感性分析显示,在所有参数中,扩繁效率对RP和BCR的影响最大。基因型与环境互作的敏感性分析表明:重排效应(养殖环境对同一基因型个体在不同环境中育种值排序的影响)对RP和BCR的影响较大。规模效应(养殖环境对遗传方差的影响)对RP和BCR的影响不如重排效应明显。因此,从遗传学和经济学角度考虑,如果育种目标性状在不同的区域间存在较强的基因型与环境互作效应,应针对不同的环境设置多个独立的育种核心群体,以期获得更高的RP和BCR。  相似文献
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Interactions between bivalve shellfish farms and fishery resources   总被引:3,自引:0,他引:3  
Mark T. Gibbs   《Aquaculture》2004,240(1-4):267-296
The only possible way to increase seafood yields from many coastal and continental shelf regions of the world is through aquaculture. The most ecologically efficient forms of aquaculture are those operations culturing plants and lower trophic level animals, such as bivalve molluscs. It is therefore understandable why culturing of these organisms has steadily increased over at least the last two decades. However, the expansion of large-scale aquaculture has costs in terms of loss of water space that could be used for other activities, and carbon flows directed through the bivalves that could have been used to support other marine plants and animals (predation and production foregone). The dominant present users of many, if not most, coastal and continental shelf regions are commercial and, in some cases, recreational and indigenous customary fishers. Therefore, in many cases, it is these stakeholders who will stand to pay much of the direct costs of the expansion of aquaculture. Therefore, it is inevitable that in some cases, there will be conflict between these sectors as water space becomes more in demand and, hence, more valuable. Resource managers are therefore faced with making resource allocation decisions between alternate sectors, and these decisions should be based on robust knowledge of the costs and benefits of each alternative use. In the case of allocation decisions between bivalve aquaculture and wild stock fisheries, there is presently a paucity of knowledge surrounding the interactions between these two activities. The aim of the work presented here was to develop a framework for understanding these interactions and applying the framework in a case study in New Zealand.  相似文献
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