全文获取类型
收费全文 | 399篇 |
免费 | 20篇 |
专业分类
林业 | 27篇 |
农学 | 11篇 |
96篇 | |
综合类 | 50篇 |
农作物 | 25篇 |
水产渔业 | 37篇 |
畜牧兽医 | 134篇 |
园艺 | 14篇 |
植物保护 | 25篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 18篇 |
2020年 | 21篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 11篇 |
2012年 | 35篇 |
2011年 | 42篇 |
2010年 | 16篇 |
2009年 | 22篇 |
2008年 | 19篇 |
2007年 | 25篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 23篇 |
2003年 | 11篇 |
2002年 | 17篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1998年 | 1篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
411.
Kåre Nolde Nielsen Michaela Maria Aschan Sveinn Agnarsson Marta Ballesteros Alan Baudron Maria de Fátima Borges Aida Campos Rosa Chapela Anna Kristín Daníelsdóttir Karim Erzini Ólavur Gregersen Petter Holm Alessandro Lucchetti Sveinn Margeirsson Hugo Vilela Mendes Petter Olsen Mafalda Rangel Antonello Sala José Luis Santiago Sigríður Sigurðardóttir Cristina Silva Daryl Sykes Jónas Rúnar Viðarsson Massimo Virgili Laura Wise Paul George Fernandes 《Fish and Fisheries》2018,19(2):363-376
We present a framework for results‐based management (RBM) of commercial fisheries. The core idea of RBM is to reduce micromanagement by delegating management responsibility to resource users. The RBM framework represents an industrial organization approach to co‐management and comprises three defining processes, conducted by three independent “agents”: (i) an “authority” defines specific and measurable and achievable objectives (outcome targets, OTs) for the utilization of fisheries resources, (ii) resource user organizations (termed “operators”) take responsibility for achieving these OTs and provide documentation that (iii) allows independent “auditors” to evaluate the achievement of OTs. Using incentive mechanisms, notably deregulation, RBM grants operators the flexibility to develop and implement innovative and cost‐effective ways to achieve OTs. The feasibility of implementing RBM in five European fisheries was investigated in cooperation with relevant stakeholders through artificial planning processes and computer simulations. The operators involved were enthusiastic, and new management plans were drafted based on the framework. These included socioeconomic OTs in addition to traditional stock objectives, encompassing an ecosystem approach. Several issues are in need of further research to consolidate the approach and prepare the ground for practical implementation, including: the specification of the legal and regulatory framework required to underpin RBM, details of transitional arrangements when shifting towards RBM (including cost‐sharing) and the development of necessary organizational capacity for operators. Initially, we therefore envisage the framework being applied to high‐value single‐species fisheries, with a limited number of participants, which are adequately represented by a competent organization. 相似文献
412.
413.
Kamila Câmara Correia João Victor Jansen de Queiroz Ricardo Brainer Martins Alessandro Nicoli Emerson Medeiros Del Ponte Sami Jorge Michereff 《European journal of plant pathology / European Foundation for Plant Pathology》2017,149(2):269-276
A standard area diagram set (SADs) with eight severity values ranging from 0.5 to 32% was evaluated as a tool to improve the accuracy of the estimates of Phomopsis leaf blight severity on eggplant by ten inexperienced raters. A first assessment in a 50-leaf dataset of digital images was performed unaided (UN, no SAD). Two further aided (A) assessments, conducted two (A1) and four weeks after the first (A2) unaided one were performed. The precision of the estimates, as indicated by the Pearson’s correlation coefficient (r), improved significantly when using the aid (A1: r = 0.96 and A2: r = 0.96) compared to unaided (UN: r = 0.79). However, the generalized bias (C b) was not significantly affected because the unaided estimates were already quite accurate (C b = 0.93). The overall concordance (ρ c) was significantly improved due to the large gains in precision when using the SADs. The raters’ estimates were more uniform (ρ c > 0.9) when using the aid, with progressive gains in the reliability of the estimates among them, indicated by the concordance correlation coefficient statistics. The SADs proposed in this study will be useful in severity estimation during field work involving multiple raters, especially as use of the SADs results in less variable estimates, improving accuracy and reliability among raters. 相似文献
414.
In future decades, initiatives on biomass-based energy development in Europe should reduce fossil fuel dependence and help to combat climate change as required by the conference of the parties 21. In this context, forest biomass can play a key role within the bioenergy sector due to its high growth potential. The use of forest biomass for energy has positive and negative effects on other ecosystem services, on stand characteristics, and on forest management practices. The aim of this study is to analyse the effects of forest bioenergy production on six ecosystem services (biodiversity, recreation, landscape aesthetics, carbon sequestration, soil erosion protection, water quality). These effects have been assessed by 80 experts in two countries (Italy and Turkey), considering two different forest management practices (clear-cutting of coppices and woody residue removal after felling in high forests). The results show that coppice clear-cutting has negative effects on almost all ecosystem services according to the experts’ opinions. The highest negative effects are on landscape aesthetics and soil protection. The effects of woody residue removal on biodiversity, carbon sequestration, soil erosion protection, and water quality are considered negative by the experts, while the effects on recreation activities and landscape aesthetics are considered positive. The highest negative effects of this forest management scenario are on soil protection and biodiversity. The experts’ opinions about the effects of forest management practices on ecosystem services can provide information to understand the environmental sustainability of bioenergy development in future years. 相似文献
415.
Functionalization of a nanostructured hydroxyapatite with Cu(II) compounds as a pesticide: in situ transmission electron microscopy and environmental scanning electron microscopy observations of treated Vitis vinifera L. leaves 下载免费PDF全文
416.
Alessandro Bonanno 《Agriculture and Human Values》1998,15(3):223-242
In liberal thought, democracy is guaranteed by the unity of community and government. The community of citizens elects its government according to political preferences. The government rules over the community with powers that are limited by unalienable human, civil, and political rights. These assumptions have characterized Classical Liberalism, Revisionist Liberalism, and contemporary Neo-Liberal theories. However, the assumed unity of community and government becomes problematic in Global Post-Fordism. Recent research on the globalization of the economy and society has underscored the increasing inability of nation-states to exercise power over their communities, which, in turn, limits the ability of communities to express their will at the nation-state level. The current phase of capitalism is characterized by socio-economic relations that transcend the jurisdictions of nation-states and local spaces. By introducing features characteristic of Classical Liberalism, Revisionist Liberalism and Neo-liberalism, and the contribution of the theory of Reflexive Modernization, which represents a novel attempt to rethink democracy within the liberal tradition, the issue of the fracture of the unity of community and government can be addressed. The inability of governments to control economic and non-economic environments creates a crisis of representation that implies serious limits to liberal democracy. This situation is particularly important for the agricultural and food sector since its development and programs for its democratization have been historically based on the intervention of agencies of and control by the nation-state. 相似文献
417.
418.
Paolo Guidetti Piero Addis Fabrizio Atzori Simona Bussotti Antonio Cal Alessandro Cau Jean‐Michel Culioli Giuseppe De Lucia Antonio Di Franco Manfredi Di Lorenzo Maria Cristina Follesa Vittorio Gazale Giorgio Massaro Francesco Mura Augusto Navone David Pala Pier Augusto Panzalis Antonio Pusceddu Alberto Ruiu Angelo Cau 《水产资源保护:海洋与淡水生态系统》2019,29(4):537-545
419.
Antonello Sala Joana dArc Prat Farran Josefina Antonijuan Alessandro Lucchetti 《Fisheries Research》2009,100(2):156-166
A new door has been designed to reduce hydrodynamic drag coefficient and increase spread of door commonly used in the Mediterranean commercial demersal trawl fisheries. Flume tank testing and engineering sea trials provide data which allow us to illustrate the performance and impact on the seabed of an existing door and a new door design. In the flume tank, each model was tested over a range of attack angles and for a limited range of otterboard heels. Curves of spreading-, drag- and down-force coefficients have been calculated. In the case of sea trials in order to extract the hydrodynamic coefficients an analysis has been applied and a mathematical model was used to calculate attack angle functions. From analysing the differences between engineering sea trials and flume tank tests we have deduced some conclusions about additional ground contact forces on sea trials that affect the performance of the doors. Moreover, a comparison between reaction forces of the flume tank and the estimation of reaction forces at sea has been given. Finally, this study allowed us to notice important differences between traditional and experimental otterboards. 相似文献