全文获取类型
收费全文 | 772篇 |
免费 | 53篇 |
国内免费 | 1篇 |
专业分类
林业 | 32篇 |
农学 | 26篇 |
基础科学 | 8篇 |
96篇 | |
综合类 | 101篇 |
农作物 | 58篇 |
水产渔业 | 79篇 |
畜牧兽医 | 330篇 |
园艺 | 18篇 |
植物保护 | 78篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 10篇 |
2020年 | 7篇 |
2019年 | 24篇 |
2018年 | 17篇 |
2017年 | 19篇 |
2016年 | 27篇 |
2015年 | 18篇 |
2014年 | 11篇 |
2013年 | 37篇 |
2012年 | 55篇 |
2011年 | 63篇 |
2010年 | 31篇 |
2009年 | 38篇 |
2008年 | 54篇 |
2007年 | 51篇 |
2006年 | 50篇 |
2005年 | 40篇 |
2004年 | 39篇 |
2003年 | 30篇 |
2002年 | 26篇 |
2001年 | 12篇 |
2000年 | 29篇 |
1999年 | 9篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1938年 | 1篇 |
1930年 | 1篇 |
排序方式: 共有826条查询结果,搜索用时 15 毫秒
821.
The Journal of Biomedical Discovery and Collaboration was created to provide, for the first time, a unified forum to consider all factors that affect scientific practice and scientific discovery – with an emphasis on the changing face of contemporary biomedical science. In this endeavor we are bringing together three different groups of scholars: a) laboratory investigators, who make the discoveries that are the currency of the scientific enterprise; b) computer science and informatics investigators, who devise tools for data analysis, mining, visualization and integration; and c) social scientists, including sociologists, historians, and philosophers, who study scientific practice, collaboration, and information needs. We will publish original research articles, case studies, focus pieces, reviews, and software articles. All articles in the Journal of Biomedical Discovery and Collaboration will be peer reviewed, published immediately upon acceptance, freely available online via open access, and archived in PubMed Central and other international full-text repositories. 相似文献
822.
Pan X Kadla JF Ehara K Gilkes N Saddler JN 《Journal of agricultural and food chemistry》2006,54(16):5806-5813
Twenty-one organosolv ethanol lignin samples were prepared from hybrid poplar (Populus nigra xP. maximowiczii) under varied conditions with an experimental matrix designed using response surface methodology (RSM). The lignin preparations were evaluated as potential antioxidants. Results indicated that the lignins with more phenolic hydroxyl groups, less aliphatic hydroxyl groups, low molecular weight, and narrow polydispersity showed high antioxidant activity. Processing conditions affected the functional groups and molecular weight of the extracted organosolv ethanol lignins, and consequently influenced the antioxidant activity of the lignins. In general, the lignins prepared at elevated temperature, longer reaction time, increased catalyst, and diluted ethanol showed high antioxidant activity. Regression models were developed to enable the quantitative prediction of lignin characteristics and antioxidant activity based on the processing conditions. 相似文献
823.
The notion of dark networks has recently received attention in the literature on policy network analysis. Dark networks are defined as illegal and covert, in contrast to bright networks which are legal and overt. In this article, we suggest a third category – grey networks – which are characterised by their use of secrecy and concealment despite their ostensibly legal status. These networks are subject to contradictory imperatives. They employ methods that cannot be openly acknowledged within the larger legal and social framework in which they function. In this article, we illustrate this concept through an interview‐based study of Australia's immigration detention network. This network enacts a deterrence policy which has been widely condemned as breaching Australia's obligations under international law. At the same time, it is required to maintain a façade of lawfulness and respect for human rights. 相似文献
824.
Retrospective Evaluation of Whole Body Computed Tomography for Tumor Staging in Dogs with Primary Appendicular Osteosarcoma
下载免费PDF全文
![点击此处可从《Veterinary surgery : VS》网站下载免费的PDF全文](/ch/ext_images/free.gif)
825.
Aida Cuni-Sanchez Marion Pfeifer Rob Marchant Patrícia V. Pompeu Neil D. Burgess 《New Forests》2018,49(4):511-528
There has been an increasing interest in fodder trees and their potential to help the rural poor. However, few studies have addressed the ecological impacts of fodder tree harvesting. We investigated the species harvested and the techniques used, and the effects of fodder harvesting on (1) species’ populations and (2) forest carbon stocks in three montane forests in Kenya. Focus-group discussions were organized in 36 villages to determine which species were harvested and with which techniques. Field observations were made on vegetation plots: stem diameter, tree height, species and extent of harvest were recorded. Carbon stocks were calculated using an allometric equation with (1) observed height of harvested trees, and (2) potential height estimated with a power model, and results were compared. Eight tree species were commonly harvested for fodder using different techniques (some branches, main stem, most branches except stem apex). Fodder harvesting (together with other uses for some species) negatively affected one species populations (Olea europaea), it did not negatively affect four (Drypetes gerrardii, Gymnosporia heterophylla, Pavetta gardeniifolia, Xymalos monospora), and more information is needed for three species (Olea capensis, Prunus africana, Rinorea convallarioides). Fodder harvesting did not significantly reduce forest carbon stocks, suggesting that local communities could continue using these fodder trees if a carbon project is established. Among the fodder species studied, X. monospora could be used in reforestation programs, as it has multiple uses and can withstand severe pruning. Although our study is only a snapshot, it is a baseline which can be used to monitor changes in fodder harvesting and its impacts related to increasing droughts in northern Kenya and increasing human populations. 相似文献
826.
Ian P. Adams Adrian Fox Neil Boonham Sébastien Massart Kris De Jonghe 《European journal of plant pathology / European Foundation for Plant Pathology》2018,152(4):909-919
High throughput sequencing informed diagnostics is revolutionising plant pathology. The application of this technology is most advanced in plant virology, where it is already becoming a front-line diagnostic tool and it is envisaged that for other types of pathogen and pests this will be the case in the near future. However, there are implications to deploying this technology due to a number of technical and scientific challenges. Firstly, interpretation of data and the assessment of plant health risk against a limited baseline of existing knowledge of the presence of pathogens in a given geographic region. Secondly, evidence of causality and the separation of pathogenic from commensal organisms in the sequence data, thirdly, the tension between the generation of a rapid sequence result with the necessary but laborious epidemiological characterisation in support of plant health risk assessment. Finally, the validation and accreditation of methods based on this rapidly evolving technology. These in turn present challenges for plant health policy and regulation. This review discusses the development of this technology, its application in plant health diagnostics, and explores the implications of applying this technology in the plant health setting. 相似文献