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21.
农民专业合作组织在实践中已经成为我国农村经济发展的合理选择,但在其创建过程中还受到多种因素的制约,运用新制度经济学有关制度变迁与创新理论,从合作组织发起人与社员的制度博弈均衡的角度阐发了合作组织创建的内在机制。  相似文献   
22.
According to the dictionary, a system is something like “a group or combination of interrelated, interdependent, or interacting elements forming a collective entity”. In postharvest, fresh harvested food crops can be considered isolated small scale systems. Postharvest research aims to understand the quality of these ‘systems’ as influenced by postharvest conditions. The phenotypic quality of horticultural produce is based on genetic traits that are expressed through a cascade of reactions subject to complex regulatory mechanisms and diverse environmental conditions. Ultimately, to fully understand postharvest phenomena, a systemic approach that links genetic and environmental responses and identifies the underlying biological networks is required. Thanks to the development of high throughput omics techniques such system-wide approaches have become a viable option to support traditional postharvest research. This review provides an overview of systems biology and how it can lead postharvest research into a new era.  相似文献   
23.
Developing the rural agricultural input markets in sub-Saharan Africa can improve the current low productivity of smallholder farmers. Malawi has seen significant efforts in addressing the availability of agricultural inputs at village level in the last few years; for example, the improvement of rural agro-dealer networks. Nevertheless inputs are still difficult to obtain for many remote smallholder farmers. Spatial analysis can help in the expansion of input stockists, especially agro-dealer networks, by assessing the coverage of existing input outlets and deriving optimum locations for village-level input stockists.We address three research questions. First, what is the locational efficiency of the current village-level stockists of inputs (Citizens Network for Foreign Affairs – Rural Agricultural Market Development Trust trained network of agro dealers and public sector)? Secondly, how many village-level stockists of markets are needed to reach 60% of the population in the central region of Malawi within one hour? Finally we address the potential spatial components of the sustainability of input stockists relating to the potential demand from smallholder farmers and the access to bulk supplies. The problem of finding the optimum location for village-level stockists of markets is addressed in two stages, using spatial analysis in conjunction with location–allocation models. First, the locational efficiency of the existing network of stockists of inputs is determined, followed by the establishment of a set of optimal sites for village-level stockists of inputs. A final step explores the viability of stockists and calculates the population surrounding the stockists taking into account competition from other sources of inputs and the accessibility of the selected stockists to potential wholesalers who are bulk distributors of farm inputs.Our results show that locational efficiency can be assessed in terms of the differential access of households to resources and transport. Often, these differences are not considered in covering problems and can have a large effect on the physical access to inputs. The results can be used to define which areas are inherently difficult to serve with agricultural inputs and could inform efforts to provide incentives to remote areas. Further implications for input policies in Malawi are that improvements in road infrastructure might not directly benefit the poorest farmers (if they are walking) but could serve to reduce the wholesale prices and therefore the retail price. In addition, the improvement in roads might increase the number of potential customers of any particular stockist, with economies of scale allowing the reduction of prices while ensuring a satisfactory profit margin for the stockist. The results of our models imply that Citizens Network for Foreign Affairs may need to train stockists over a wider area to increase the access to inputs of those smallholder farmers with least resources.  相似文献   
24.
自2002年,联合国粮农组织(FAO)发布了“全球重要农业文化遗产”(GIAHS)项目,中国学者们一直在探索适合中国农业文化遗产的保护与发展之路。回顾中国知网全文数据库上2006—2019年学者们发表的学术论文,对具有代表性的刊物上发表的相关文献进行整理归纳,结合部分实地考察的案例,阐述了中国重要农业文化遗产可持续发展的经济价值、生态价值和社会价值,分析了可持续发展过程中面临的传统生产模式退变、生态系统退化、文化传承意识薄弱、申报资料欠妥等问题,最后提出了可持续发展的策略,包括创新生产模式、激发文化创意内涵、完善相关文件等。中国重要农业文化遗产的保护固然重要,但探索其可持续发展之路,才是让其一直生存下去的根本,而这条道路不仅需要各位学者的学术研究,更需要政府和实践家的资金、时间和实践的投入,需要各行各业的共同努力。  相似文献   
25.
客观评价图书馆采编业务外包工作中代理机构的优势,及高校图书馆采编业务外包操作过程中遇到的实际问题,分析了高校图书馆现阶段采编业务外包的利弊及解决的方法。  相似文献   
26.
浙江庆元香菇文化系统景观特征及演变   总被引:1,自引:0,他引:1  
浙江省庆元县是世界人工栽培香菇的发源地, 2014年庆元香菇文化系统入选中国重要农业文化遗产。农业遗产景观是农业文化遗产在现代生活中最直观的表现,研究遗产地的景观特征和演变状况,有助于深入理解区域景观的状况及影响因素,实现遗产的有效保护和发展。本文运用Landsat 1991年、2001年、2010年和2018年的卫星影像结合实地调研,研究庆元香菇文化系统遗产地的景观现状、特征及结构,分析1991—2018年各景观类型演变规律及可能驱动要素。结果表明:1)遗产地景观类型主要包括森林、耕地、居民地和水体4类,其中森林面积达到1 643.23km~2(86.61%),是优势景观类型。2)区内山高、林密、溪流和菌菇资源丰富,形成了"河流-村落-梯田-森林"的垂直景观结构,并拥有西洋殿、菇寮等独特的香菇文化景观,人类与自然环境和谐共生。3)1991—2018年,遗产地森林面积增加139.28km~2(7.34%),耕地面积减少154.53km~2(8.15%),居民地面积增加11.86km~2(0.63%),水体面积增加3.48km~2(0.18%)。4)景观变化与相关政策密切相关, 20世纪后半期,遗产地森林砍伐严重,森林覆盖率由79.27%降低到77.97%; 21世纪以来,封山育林和生态林业建设使森林覆盖率从77.97%上升至86.61%,退耕还林和城镇化政策则分别促使了耕地面积减少和居民地面积的微弱扩张。总之,浙江庆元香菇文化系统遗产地景观结构独特,得益于当地居民林-菇共育的传统理念、香菇栽培技术的进步和当地森林保护等政策的施行,遗产地森林面积经历轻微的下降后又迅速增加,为遗产保护和传承提供了保障。  相似文献   
27.
Abstract

Deforestation is a complex and a dynamic process. Conventionally, deforestation has been analyzed on a factor by factor level, using linear and static approaches that ignored the feedback mechanisms. This paper investigated the problem of deforestation at a systems level and analyzed the process through a systems dynamic language to overcome these limitations. A case study of deforestation in India is discussed to illustrate the use of a simple systems dynamic model. The model highlights the fact that current policies have narrowly focused on the legally mapped area of forest land while overlooking the rapid erosion of biomass from these same forest lands. The model forecasts the scenario for India under optimistic assumptions where population, the fraction of forest encroached, the forest productivity, and the total forest biomass removal all remain at current levels. Despite these optimistic assumptions, the model forecasts that over the next ten to fifteen years both the total forest area and the forest biomass in India will rapidly decline.  相似文献   
28.
SUMMARY

Cropping systems in the Midwest USA are evolving as farmers seek labor-efficient designs to capture and use available light and precipitation. Heavy reliance on fossil fuels and other energy-intensive production inputs coupled with uncertain markets for commodities have encouraged the search for greater energy efficiency as well as alternative crops, markets, and production systems. Agroecology has emerged as an innovative and integrative approach to evaluating systems more suited to the often harsh and unpredictable environment, using native prairie structure and function as one guide to design of future systems. A more specific approach, Natural Systems Agriculture, is being explored as a new paradigm to saving soil while producing the crop and animal output needed for a growing global population. Whole-farm and landscape-level design and planning will become more important as society recognizes and values multifunctional rural landscapes.  相似文献   
29.
Reserves are often designed to protect rare habitats, or “typical” exemplars of ecoregions and geomorphic provinces. This approach focuses on current patterns of organismal and ecosystem-level biodiversity, but typically ignores the evolutionary processes that control the gain and loss of biodiversity at these and other levels (e.g., genetic, ecological). In order to include evolutionary processes in conservation planning efforts, their spatial components must first be identified and mapped. We describe a GIS-based approach for explicitly mapping patterns of genetic divergence and diversity for multiple species (a “multi-species genetic landscape”). Using this approach, we analyzed mitochondrial DNA datasets from 21 vertebrate and invertebrate species in southern California to identify areas with common phylogeographic breaks and high intrapopulation diversity. The result is an evolutionary framework for southern California within which patterns of genetic diversity can be analyzed in the context of historical processes, future evolutionary potential and current reserve design. Our multi-species genetic landscapes pinpoint six hotspots where interpopulation genetic divergence is consistently high, five evolutionary hotspots within which genetic connectivity is high, and three hotspots where intrapopulation genetic diversity is high. These 14 hotspots can be grouped into eight geographic areas, of which five largely are unprotected at this time. The multi-species genetic landscape approach may provide an avenue to readily incorporate measures of evolutionary process into GIS-based systematic conservation assessment and land-use planning.  相似文献   
30.
This paper examines the effects of a single surface application of biosolids (at 20 dry Mg ha? 1) on plant species composition, forage quality and quantity, and C stocks after 14 yr of rest in rangelands of the Central Interior of British Columbia. More than two times the aboveground biomass of grasses and the percent cover of plant litter were found in the biosolids treatment relative to the control, along with reductions in bare soil and microbiotic crust cover. Significantly greater plant uptake of all macronutrients (C, N, P, K, S, Ca, and Mg); most micronutrients (B, Cu, Mn, Mo, and Zn); and Al occurred in the biosolids treatment. P and Cu were the only two nutrients to be more concentrated in the biosolids-treated forage relative to the control forage, while N, Mg, and protein were more concentrated in the control forage. No significant difference in forage digestibility was found between biosolids and control treatments. Bluebunch wheatgrass, the late-seral native grass species, had significantly increased cover and aboveground biomass in the biosolids treatment relative to the control; however, between 2006 and 2016, non-native Kentucky bluegrass had reached > 25% cover in the biosolids plots, perhaps restricting the full recovery of bluebunch wheatgrass. Our findings indicate that biosolids application to ungrazed rangeland can increase long-term forage production and reduce bare soil. However, at our study site biosolids application also led to a long-term shift in the plant community composition away from the late-seral (i.e., bluebunch wheatgrass) trajectory, and the effects of this shift on rangeland health and productivity require further investigation.  相似文献   
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