全文获取类型
收费全文 | 109篇 |
免费 | 4篇 |
专业分类
林业 | 54篇 |
农学 | 2篇 |
基础科学 | 1篇 |
6篇 | |
综合类 | 11篇 |
水产渔业 | 3篇 |
畜牧兽医 | 32篇 |
植物保护 | 4篇 |
出版年
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2014年 | 3篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2000年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1957年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有113条查询结果,搜索用时 203 毫秒
81.
82.
83.
84.
ABSTRACT: Over recent years the growth in aquaculture, accompanied by the emergence of new and transboundary diseases, has stimulated epidemiological studies of aquatic animal diseases. Great potential exists for both observational and theoretical approaches to investigate the processes driving emergence but, to date, compared to terrestrial systems, relatively few studies exist in aquatic animals. Research using risk methods has assessed routes of introduction of aquatic animal pathogens to facilitate safe trade (e.g. import risk analyses) and support biosecurity. Epidemiological studies of risk factors for disease in aquaculture (most notably Atlantic salmon farming) have effectively supported control measures. Methods developed for terrestrial livestock diseases (e.g. risk-based surveillance) could improve the capacity of aquatic animal surveillance systems to detect disease incursions and emergence. The study of disease in wild populations presents many challenges and the judicious use of theoretical models offers some solutions. Models, parameterised from observational studies of host pathogen interactions, have been used to extrapolate estimates of impacts on the individual to the population level. These have proved effective in estimating the likely impact of parasite infections on wild salmonid populations in Switzerland and Canada (where the importance of farmed salmon as a reservoir of infection was investigated). A lack of data is often the key constraint in the application of new approaches to surveillance and modelling. The need for epidemiological approaches to protect aquatic animal health will inevitably increase in the face of the combined challenges of climate change, increasing anthropogenic pressures, limited water sources and the growth in aquaculture. TABLE OF CONTENTS: 1 Introduction 42 The development of aquatic epidemiology 73 Transboundary and emerging diseases 93.1 Import risk analysis (IRA) 103.2 Aquaculture and disease emergence 113.3 Climate change and disease emergence 133.4 Outbreak investigations 134 Surveillance and surveys 154.1 Investigation of disease prevalence 154.2 Developments in surveillance methodology 164.2.1 Risk-based surveillance and scenario tree modelling 164.2.2 Spatial and temporal analysis 164.3 Test validation 175 Spread, establishment and impact of pathogens 185.1 Identifying routes of spread 185.1.1 Ex-ante studies of disease spread 195.1.2 Ex-post observational studies 215.2 Identifying risk factors for disease establishment 235.3 Assessing impact at the population level 245.3.1 Recording mortality 245.3.2 Farm health and production records 265.3.3 Assessing the impact of disease in wild populations 276 Conclusions 317 Competing interests 328 Authors' contributions 329 Acknowledgements 3310 References 33. 相似文献
85.
YANG Xiu-shi ;WANG Li-jun ;DONG Chuan ;Edmund Man King Lui ;REN Gui-xing 《中国农业科学(英文版)》2014,(12):2807-2815
Ultrasonic-assisted extraction (UAE) of American ginseng polysaccharides (AGP) was investigated using response surface methodology. Three-factor-three-level Box-Behnken design was employed to optimize the ultrasonic power, extraction time and ratio of water to raw material to obtain a high AGP yield. The analysis of variance and response surface plots indicated that ultrasonic power was the most important factor affecting the extraction yield. The optimal conditions were ultrasonic power 400 W, extraction time 71 min, and ratio of water to raw material 33 mL g-1. Under these conditions, the yield of AGP was 8.09%, which was agreed closely to the predicted value. Gas chromatography (GC) analysis showed that AGP was composed of arabinose, rhamnose, galactose, glucose, and galacturonic acid. Fourier transform infrared spectra revealed the general characteristic absorption peaks of AGP. In addition, AGP exhibited good immunostimulating activities by up-regulating the production of nitric oxide and cytokines. Compared with hot water extraction, UAE required shorter extraction time and gave a higher extraction yield, without changing the structure and immunostimulating activity of AGP. The results indicated that UAE could be an effective and advisable technique for the large scale production of plant polysaccharides. 相似文献
86.
Edmund Leib 《Journal of pest science》1973,46(5):74-75
Summary
The new decree for protection of bees
The new decree is represented as an example for a measure directed to the protection of the world ariund us. Prohibitions, orders and obligations in connection with the protection of bees on occasion of chemical control of pests are described.
7737 Bad Dürrheim, Königsberger Straße 35. 相似文献
7737 Bad Dürrheim, Königsberger Straße 35. 相似文献
87.
88.
Edmund J Leigh Edward Mackillop Ian D Robertson Lola C Hudson 《Veterinary radiology & ultrasound》2008,49(2):113-121
The purpose of this study was to produce an magnetic resonsnce (MR) image atlas of clinically relevant brain anatomy and to relate this neuroanatomy to clinical signs. The brain of a large mixed breed dog was imaged in transverse, sagittal, and dorsal planes using a 1.5 T MR unit and the following pulse sequences: Turbo (fast) spin echo (TSE) T2, T1, and T2- weighted spatial and chemical shift-encoded excitation sequence. Relevant neuroanatomic structures were identified using anatomic texts, sectioned cadaver heads, and previously published atlases. Major subdivisions of the brain were mapped and the neurologic signs of lesions in these divisions were described. TSE T2-weighted images were found to be the most useful for identifying clinically relevant neuroanatomy. Relating clinical signs to morphology as seen on MR will assist veterinarians to better understand clinically relevant neuroanatomy in MR images. 相似文献
89.
Machine-to-machine communication for agricultural systems: An XML-based auxiliary language to enhance semantic interoperability 总被引:3,自引:0,他引:3
This paper puts forth an Internet-based architecture for machine-to-machine communication and computation that enhances bio-productivity in agriculture. The approach utilizes an auxiliary language to enable data interoperability in a synthetic computing environment and to make connections between data and mathematical models. The approach also includes some aspects of cloud and context aware computing. At the prototype level, a practical application from the Florida citrus industry demonstrates the concept. In general, future agricultural systems will be Internet-based thus reducing cost and increasing capability. Standards organizations are certain to play an important role in this development, which might continue for the next decade or longer. 相似文献
90.