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河湖水系保持连通是流域内河流与湖泊、河道与河漫滩之间物质流、能量流、信息流和物种流保持畅通的基本条件,也是优化水资源配置战略格局、提高水利保障能力、促进水生态文明建设的有效举措。利用GIS平台和图论理论,研究河湖水系的系统性连通程度定量评价技术,以胶东地区为例,分析了胶东调水东线工程和引黄济青工程实施后山东半岛东部地区水网连通情况。结果表明,胶东调水东线工程实施后连通度可提高50%。此方法可为平原水网区水生态保护与修复、河湖水系连通规划及闸坝调度方案优化等提供技术支持。  相似文献
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河蚌结缔组织细胞发生及发育观察   总被引:3,自引:3,他引:10  
刘小明 《水产学报》1991,15(2):124-129
对河蚌外套膜组织学观察发现,外套膜结缔组织发源于细胞聚合体。聚合体细胞发育形成结缔组织细胞及组织构造。外套膜边缘“类聚合体”细胞增殖和发育形成边缘结缔组织。聚合体细胞发育形成不同形状细胞(成纤维细胞和颗粒细胞)。两者不断变化:成纤维细胞积累颗粒最终发育成球状颗粒细胞。球状细胞解体释放颗粒后恢复分泌纤维质状态。纤维物质重新组合排列构成贝体组织骨架,颗粒物质参与贝壳形成。  相似文献
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Abstract –  Movements of fish, in particular roach Rutilus rutilus , perch Perca fluviatilis, rudd Scardinius erythrophthalmus, bleak Alburnus alburnus and chub Leuciscus cephalus (age ≥ 1+) in relation to environmental variables were examined between the River Morava, Czech Republic, and a rehabilitated former meander. Data were taken over seven 24-h periods in April–June 1997 using two back-to-back traps. Of 170 fish captured, 70% moved from the backwater to the river. Diel activity differed between sampling dates, but overall bleak, roach and chub moved mainly between dusk and dawn, whereas perch moved throughout most of the day. Rudd showed bi-modal (mid-day, midnight) activity. However, avoidance behaviour could have biased results for species known to be wary of traps. Water level changes, temperature and illumination were among the main environmental factors influencing fish movement, along with spawning migrations relevant for most species. In all specimens, over 65% individuals captured were ready to spawn. Most of them, except for perch, were moving out of the backwater towards the river.  相似文献
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Sex change and the genetic structure of marine fish populations   总被引:1,自引:0,他引:1  
The interaction between environmental forces and dispersal characteristics is largely responsible for the patterns of population structure in marine fish. Yet, crucial gaps in knowledge on life-histories and the relative contributions of numerous environmental factors still hinder a thorough understanding of marine population connectivity. One life-history trait so far overlooked by most fish population geneticists is sequential hermaphroditism, whereby individuals first mature as one sex and later in life reverse into the other sex. Population genetic theory predicts that sex-changing fish will present a higher potential for more spatially structured populations than gonochoristic species, as a result of their naturally skewed sex ratio, which is expected to reduce effective population size and hence increase genetic drift. We gathered published data on genetic population structure in marine fish, as summarized by the popular F ST index, and – after controlling for several potentially confounding factors – we tested the hypothesis that sex-changing species are more genetically structured than gonochoristic ones. Although we found no evidence to support the theoretical expectations, our results suggest new working hypotheses that can stimulate new research avenues at the intersection between physiology, genetics and fisheries science.  相似文献
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Storage of lipids in the myosepta of Atlantic salmon (Salmo salar) was determined by dissection of myosepta from both white and dark muscle, by analyzing lipid classes of myosepta, and by analysis of muscle tissues with and without myosepta. By using Iatroscan-TLC/FID it was found that triglyceride was the only major lipid class present in the myosepta. In a sample pooled from three fish, 39.1% of white muscle lipids were found to be stored in the associated myosepta. In the dark muscle up to 62.4% of the total lipids were located in the associated myosepta.After removal of the myosepta, the ratio of the total lipid content of dark muscle to white muscle decreased from 5.25 to 3.66. The proportion of polar lipids increased in both white muscle and dark muscle after removal of the myosepta; however the ratio of phosphatidyl choline (PC) to phosphatidyl ethanolamine (PE) in both muscle types remained constant. This suggests that neutral lipids accounted for most of the lipids in the myosepta. It is concluded that this type of connective tissue, not the actual muscle fibres, stores most of the muscle lipids in Atlantic salmon.  相似文献
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