首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   22篇
  免费   1篇
  国内免费   2篇
丛书文集   1篇
教育与普及   1篇
综合类   18篇
自然研究   5篇
  2018年   2篇
  2017年   1篇
  2013年   1篇
  2012年   5篇
  2011年   1篇
  2009年   2篇
  2003年   2篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1992年   1篇
  1989年   1篇
排序方式: 共有25条查询结果,搜索用时 31 毫秒
1.
A total of 3109 crustaceans belonging to 50 taxa distributed in 42 families were found in 117 analysed stomachs of flying gurnard (Dactylopterus volitans). Samples were obtained in April 2008 by the R/V Gyre using a bottom trawl towed in 12 stations at 14–100 m depth on the continental shelf of the Campos Basin, Brazil. The carcinofauna was analysed and the order Calanoida (Copepoda) found to be the most important item in terms of relative abundance and frequency of occurrence, followed by the order Amphipoda (Peracarida), the infraorder Brachyura (Decapoda), the order Stomatopoda and the subclass Myodocopa (Ostracoda). In the order Calanoida, the species Pontellopsis cf. villosa (Pontellidae) represented 98.04% of total crustacean abundance. The diet of Dactylopterus volitans varied according to fish size, with higher diversity of Crustacea at smaller size classes, decreasing in larger fishes. A similar pattern regarding depth was obtained, with greater diversity of taxa in gurnard stomachs caught at shallower depths. Flying gurnard is considered a generalized carnivore of invertebrates, eating mobile macrobenthic organisms, such as crustaceans, and its diet varies with its life stage, without any specific group as its main food source.  相似文献   
2.
家蝇幼虫对糖化饲料转化利用的研究   总被引:1,自引:0,他引:1  
测定了家蝇幼虫对糖化饲料的转化利用情况。通过对幼虫生物量的比较,筛选出了糖化处理饲料的优化方案为:加入糖化酶糖化,用量为0.125g/50g麦麸,糖化时间为零,饲料中加入糖化酶可提高幼虫生物量、饲料效率、饲料效率、粗蛋白及粗脂肪的转化率。初步估算了用糖化酶糖化处理饲料的经济效益。  相似文献   
3.
用在3个(28%,32%,36%)蛋白质水平上分别添加了10-4纯肉毒碱的饲料喂养相同的鲤鱼春片鱼种,分别以空白为对照组,比较添加肉毒碱对饲料的脂肪消化率的影响.结果表明,肉毒碱具有明显的促进鲤鱼饲料脂肪消化的作用,同时蛋白质含量越低的饲料,其添加的效果越好.当添加量为10-4时,饲料脂肪的消化率由大到小的顺序为蛋白质量分数分别为28%,32%,36%.  相似文献   
4.
用分别添加了质量分数为0,5×10-5,10-4,1.5×10-4,2×10-4,2.5×10-4纯肉毒碱的饲料饲养相同的鲤鱼春片鱼种,比较这些鱼对每种饲料的总(表观)消化率.结果表明,肉毒碱具有明显的促进鲤鱼饲料消化的作用,并且添加量质量分数为10-4时促消化作用最好.  相似文献   
5.
微量元素锌缺乏大鼠实验动物模型的建立和研究   总被引:5,自引:0,他引:5  
锌是人体必需的微量元素,微量元素锌缺乏是严重影响我国儿童正常发育的原因之一,有关锌对生长、生育过程营养生理作用的深入研究,已经引起了医学界的广泛关注,本项研究用自行制备的不同含锌量的人工半合成饲料,建立了生长大鼠的缺锌模型,对其生长,发育过程进行了详细的观察,结合多项血液学及生化参数的分析测试结果,对微量元素锌缺乏大鼠实验动物模型进行了讨论。  相似文献   
6.
探讨营养支持疗法对慢性呼吸衰竭并营养不良病人体液免疫功能的影响,结果表明,PN组的营养状况及体液免疫功能均明显上升(P<0.05),而对照级无显著化(P>0.05),免疫功能的上升有利于对呼衰的纠正。  相似文献   
7.
《Journal of Natural History》2012,46(13):1621-1632
The diets of all South-East Asian water snakes of the subfamily Homalopsinae are reviewed. New diet observations for 10 species of homalopsine snakes are presented. The data on four of these, Cantoria violacea, Enhydris doriea, E. longicauda and Gerarda prevostina represent the first published diet records for these species. The observations for Fordonia leucobalia, Myron richardsonii andEnhydris enhydris represent the first taxonomically detailed diet records for these three species. The records provided for Cerberus rynchops, Enhydris plumbea and Homalopsis buccata add new taxonomic categories to previous records. The records provided for Cerberus rynchops, E. plumbea and Homalopsis buccata add new taxonomic categories to previous records. Four generalities emerge from our findings: (1) freshwater homalopsines feed primarily on fish and the adults and larvae of amphibians; (2) at least four of the eight estuarial species specialize on crustaceans while two primarily prey on fish; (3) feeding on crustaceans appears to have evolved independently at least twice; (4) prey are usually less than 10% of the predator's mass. The known predators of homalopsines are summarized and include both invertebrates and vertebrates. The microhabitats of the estuarial species are discussed and related to prey and habitat preferences.  相似文献   
8.
《Journal of Natural History》2012,46(16):2005-2012
Several causes have been considered to explain the specialized ant-feeder habits of the bufonids. We analysed the diet and availability of prey items for sympatric Bufo arenarum, Bufo dorbignyi and Odontophrynus americanus living in a grassland of the flooding pampa, Argentina. Frogs and insects were captured once a month with pitfall traps during the 2-year sampling. The frogs were measured and the stomach content was analysed. Odontophrynus americanus ingests Lepidoptera larvae, Coleoptera, Diptera and Homoptera; while both Bufo species not only feed on ants, but also prefer them. Whereas the two Bufo species show high niche overlap, the niche overlapping between both Bufo and Odontophrynus americanus was low. There are significant differences among body size of both Odontophrynus americanus and Bufo arenarum when compared with B. dorbignyi ; while there are no differences in body size of O. americanus and B. arenarum. Gape is larger in Odontophrynus americanus than in Bufo dorbignyi and B. arenarum, but it is similar in the two Bufo species. The mean prey size is larger for Odontophrynus americanus, followed by Bufo arenarum and B. dorbignyi. These results would confirm that the bufonids have ant-feeder habits, perhaps due to their small edentate gape that would constitute a morphological constraint that could explain their mirmecophagic habits.  相似文献   
9.
不同蛋种鸡饲料对SPF鸡群产蛋性能的影响   总被引:2,自引:0,他引:2  
为了提高SPF鸡的生产能力和质量 ,在相同的SPF鸡饲养条件下 ,选择分别来源于北京正大和北京科澳协力生产的全价营养蛋种鸡饲料 ,经高压消毒后 ,饲喂品种相同的SPF种鸡 ,结果显示两个鸡群在生产性能方面存在明显差异 (p <0 0 1)。其中饲喂北京科澳协力饲料的SPF鸡群的产蛋率和利用率都明显高于另一个鸡群 ,主要表现在SPF鸡群开产早期的蛋重上和产蛋高峰期后产蛋率的维持上。  相似文献   
10.
《Journal of Natural History》2012,46(29-30):1767-1785
ABSTRACT

In the present study we investigated the diet of Eleonora’s falcons in Greece and assessed the regional dietary pattern of 16 breeding colonies of the Aegean. Overall 224 nests were visited and a total of 8067 prey items were collected which contained two mollusca classes, seven insect orders, one reptile family, two mammalian taxa and at least 54 avian species. Cicadas were the most common insects found in pellets (45.1%) followed by flying ants (34.8%) and beetles (15.8%) while just 20 species (33.3%) accounted for over 90% of the avian prey items identified in bird remains dominated (>50%) by the Willow Warbler (Phylloscopus trochilus), the Red-backed Shrike (Lanius collurio) and the Whitethroat (Sylvia communis). Insect feeding peaked in late August (39.8%) and late September (20.8%), whereas bird remains built up in falcon nests from mid-August onwards, culminating in late September (57.2%) and declined abruptly afterwards. Overall the falcons’ diet diversity increased as the breeding season progressed and from the north towards the south Aegean. The avian prey species richness was negatively influenced by the distance of the colonies from the mainland and the weather conditions during September which coincides with the fledgling period of the young and the autumn peak of passerine migration.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号