全文获取类型
收费全文 | 61篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
林业 | 10篇 |
农学 | 1篇 |
11篇 | |
综合类 | 8篇 |
水产渔业 | 13篇 |
畜牧兽医 | 25篇 |
园艺 | 1篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2016年 | 1篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 8篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1992年 | 1篇 |
排序方式: 共有69条查询结果,搜索用时 0 毫秒
41.
Ana Norman‐Lόpez Melony J Sellars Sean Pascoe Greg J Coman Brian Murphy Nick Moore Nigel Preston 《Aquaculture Research》2016,47(10):3287-3296
Advances in the domestication and selective breeding of Australian Black Tiger shrimp, Penaeus monodon, opens the opportunity for world producers to reconsider the benefits of farming this species. Just over a decade ago this species was the world's most farmed shrimp species, however, difficulty in its domestication, in part, led to the widespread establishment of Penaeus vannamei (Pacific White shrimp) as the most farmed shrimp species in the world. This study empirically evaluates the productivity benefits of commercially domesticating P. monodon against production from wild broodstock of the same species. The evaluation compared the relative production from commercial ponds stocked with the progeny of wild P. monodon broodstock and ponds stocked with the progeny of domesticated stocks. The production data were from 164 ponds of domesticated stocks and 30 ponds of wild stocks, collected over 4 years (2009–2013) from two separate farm sites of the same Australian shrimp farming company. The wild stocks were sourced from the east coast of Australia. The results suggested that the productivity of the selectively bred stocks was 39% greater compared with production from wild stocks given equivalent amounts of feed and other inputs. Furthermore, productivity was additionally enhanced depending on the choice of feeds and whether stocking took place in September rather than later in the year (i.e. in early spring rather than late spring/early summer in the Southern hemisphere). This suggests that there is significant potential to further enhance the productivity of P. monodon farms via integrating advances in domestication, feeds and management practices. 相似文献
42.
Tiger puffer, Takifugu rubripes, juveniles were fed with four semi-purified experimental diets containing 0.2% Ca from Ca-lactate (diet 1), no supplemental Ca (diet 2) and 0.2% and 2.5% Ca from tricalcium phosphate, TCP (diets 3 and 4), respectively. After a 10 week rearing period, growth and feed utilization were significantly lower in the fish group fed on diet 2 than in the fish group fed on diet 1. Fish groups fed on diets 3 and 4 also showed poor growth performances compared with group 1. It appears that Ca intake from seawater is not sufficient for the normal growth of tiger puffer. Furthermore, Ca in dietary TCP appeared to be unavailable to this species. Dietary TCP strongly inhibited the bone mineralization of Zn and Mn. The findings indicate that easily digestible Ca supplementation is indispensable in a diet of tiger puffer for normal growth, feed utilization and bone mineralization. © Rapid Science Ltd. 1998 相似文献
43.
44.
针对人兽冲突现状、补偿情况、野生动物保护态度等问题,通过入户访谈、调查问卷的方式对东北虎豹国家公园东宁片区两个乡镇5个村屯的居民进行了调查。结果显示,发生冲突率47.28%,人兽冲突形式有粮食减产、捕食家畜和人身伤害,造成损害的野生动物物种主要包括野猪、黑熊、东北虎、东北豹、马鹿和狍。造成的平均经济损失为8796.9元/年,其中农牧业损失最大,为10373.3元/年。但大部分野生动物损害未能得到补偿,仅1户得到了1000元的补偿款。人兽冲突的预防和缓解措施包括:规范当地居民的生产生活行为,禁止非法狩猎、在禁牧区放牧等活动;对东北虎及其他重点保护野生动物造成的损害采取经济补偿办法,建立东北虎损害保险制度;加强宣传,提高居民对东北虎等野生动物的保护意愿。 相似文献
45.
46.
历史时期,江西地区是华南虎的主要栖息地之一。然而,随着人类活动的加强和自然环境的变迁,人虎关系在明清时期表现得异常紧张,“虎患”问题成为地方政府头疼的灾害之一。以往学者在研究江西虎惠时,只是单方面强调人类无休止的开发活动压迫了虎的生存空间,最终导致虎患的发生。事实上,一些经济、文化水平较高的地区也是虎患高发地。究其原因,乃为战乱、灾荒导致人口锐减、社会残破和田地荒芜,次生林在战乱、灾荒之后得到恢复并成为战后较长一段时间内的主要植被,为虎提供了广阔的栖身之所,从而诱发了群虎入城袭击人类的事件发生。 相似文献
47.
Rajeev Pillay A.J.T. Johnsingh R. Raghunath M.D. Madhusudan 《Biological conservation》2011,(5):1567-1576
Large mammals face high risks of anthropogenic extinction owing to their larger body mass and associated life history traits. Recent worldwide mammal declines have highlighted the conservation importance of effective assessments of trends in distribution and abundance of species. Yet reliable data depicting the nature and extent of changes in population parameters is sparse, primarily due to logistical problems in covering large areas and difficulties in obtaining reliable information at large spatial scales, particularly over time. We used key informant surveys to generate detection histories for 18 species of large mammals (body mass > 2 kg) at two points in time (present and 30 years ago) in the Southern subregion of the Western Ghats global biodiversity hotspot. Multiple-season occupancy models were used to assess temporal trends in occupancy, detectability and vital rates of extinction and colonization for each species. Our results show significant declines in distribution for large carnivores, the Asian elephant and endemic ungulates and primates. There is a significant decline in detectability for 16 species, which suggests a decline in their abundance. These patterns of change in distribution and abundance repeat in our assessments of spatial variation in occupancy dynamics between the three contiguous forest complexes and two human-dominated landscapes into which the southern Western Ghats has been fragmented. Extinction rates are highest in the human-dominated landscapes. Declines in abundance for several species suggest the presence of extinction debts, which may soon be repaid with imminent range contractions and subsequent species extinctions unless immediate remedial conservation measures are taken. Detection/non-detection surveys of key informants used in an occupancy modeling framework provide potential for rapid conservation status assessments of multiple species across large spatial scales over time. 相似文献
48.
虎的血液生理生化指标可以反映虎健康状况。处于不同生长发育时期和不同状态的老虎在血液生理及生化指标值上差异较大,部分指标值具有统计学意义,可以作为不同亚种虎以及虎是否健康的判断参考指标。 相似文献
49.
Effects of dietary mannan oligosaccharide on growth, body composition and hepatopancreas histology of Penaeus semisulcatus (de Haan 1844) 总被引:1,自引:0,他引:1
The effects of dietary mannan oligosaccharides (MOS) on growth, body composition and hepatopancreas histology of Penaeus semisulcatus (postlarvae stage 20) were investigated for 48 days. Different dosages of MOS (0, 1.5, 3.0 and 4.5 g MOS kg−1) were tested in triplicate groups. Shrimp postlarvae averaging 0.34 ± 0.01 g attained 1.52 ± 0.31, 1.51 ± 0.15, 2.18 ± 0.13, 1.57 ± 0.13-g final weight and 42.7 ± 2.7, 37.3 ± 1.3, 64.0 ± 6.9, 50.7 ± 4.8% survival, respectively. At the end of the study, generally enhanced growth performance and feed conversion ratio were observed in shrimp fed on diet containing 3.0 g kg−1 MOS with the highest final live weight (2.18 ± 0.13 g) and survival rate (64.0 ± 6.9%) after 48 days of feeding. The protein contents in the whole body decreased with increasing rates of dietary MOS (P < 0.05). Different levels of dietary MOS used in this study showed no detrimental effects on hepatopancreas tissue judged by histological screening. In conclusion, 3.0 g kg−1 MOS could be used as a healthy growth promoter in shrimp diets. 相似文献
50.
[目的]研究东北虎在非繁殖期和发情交配期活动节律的差异,以及其活动节律之间是否存在性别差异。[方法]采用行为取样法对7只(3雌4雄)东北虎的发情交配期和非繁殖期进行了观察。[结果]东北虎发情交配期的主要行为包括休息、运动和发情交配,其中雌虎在发情交配期和非繁殖期休息和运动时间差别不大,而雄虎发情交配期的休息时间较非繁殖期明显下降,运动差异不明显;雌雄虎在非繁殖期和发情交配期的休息、运动和发情交配时间没有明显的性别差异。[结论]结果为优化东北虎的管理及提高其繁殖成功率提供了参考。 相似文献