首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   662篇
  免费   12篇
财政金融   64篇
工业经济   50篇
计划管理   29篇
经济学   143篇
综合类   52篇
旅游经济   4篇
贸易经济   41篇
农业经济   182篇
经济概况   109篇
  2024年   2篇
  2023年   5篇
  2022年   4篇
  2021年   8篇
  2020年   37篇
  2019年   24篇
  2018年   12篇
  2017年   41篇
  2016年   25篇
  2015年   12篇
  2014年   29篇
  2013年   32篇
  2012年   43篇
  2011年   57篇
  2010年   31篇
  2009年   50篇
  2008年   40篇
  2007年   62篇
  2006年   45篇
  2005年   16篇
  2004年   10篇
  2003年   8篇
  2002年   14篇
  2001年   31篇
  2000年   5篇
  1999年   9篇
  1998年   3篇
  1997年   2篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1985年   3篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1973年   1篇
排序方式: 共有674条查询结果,搜索用时 15 毫秒
211.
  总被引:9,自引:0,他引:9  
The continuing process of global integration bears implications for farmers and related supplying and processing industries in all parts of the world, but also for the rest of the world economy. An assessment of agricultural and trade policy impacts is bound to be complex and is often supported by quantitative modeling analysis. This article provides an assessment of the present state of applied modelling in the area of trade and agricultural policies. We provide in this paper a comparative assessment of alternative modelling approaches, considering a total of 16 partial equilibrium and general equilibrium models. The assessment includes theoretical modelling foundations, datasets employed and institutional aspects, such as model maintenance and dissemination of results. A typology of models is provided by structuring the assessment along a clear set of evaluation criteria.  相似文献   
212.
Soybean production is one of the main economic forces driving the expansion of the agricultural frontier in the Brazilian Amazon. To assess the potential for expansion we estimate a model of soybean yield that integrates the major climatic, edaphic, and economic determinants in the Amazon Basin. Yield is modeled as a function of yield as simulated by a crop physiology model that captures the effects of climate and physical attributes on the development of soybean plant; fertilizer applications; and economic/spatial parameters such as credit, transports costs and latitude. Current values of these determinants indicate that roughly 20% of Amazon Region or ∼ 1,000,000 km2 (excluding protected areas) can generate yields greater than 2000 kg/ha. Soybean production may be possible over a wider area of Amazon, but realizing this potential requires improvements in economic determinants such as the transportation infrastructure.  相似文献   
213.
The Australian agricultural sector provides food security for the nation and affects the livelihood of farmers and the development of rural communities. This sector has been uneasy about the Australian carbon tax scheme introduced in July 2012 although the government has exempted the agricultural sector from the scheme. By employing a computable general equilibrium model and an environmentally extended Social Accounting Matrix, this article simulates the effects of different carbon tax policy scenarios. The modeling results show that all agricultural sectors will be affected negatively but to differing degrees. The household compensation policy will improve the performance of the poultry and fishing sectors, while having opposite effects in the other agricultural sectors. The inclusion of the agricultural industry into the carbon tax scheme will lead to a considerable further decrease in output, employment and profitability in the agricultural sector, and a significant further reduction in real GDP, but a much larger emission reduction.  相似文献   
214.
215.
    
Precision agricultural technologies (PATs) allow more detailed management of in-field variability. Policy and advisory communities have championed PATs as a route to preserving natural capital whilst increasing productivity from agricultural land. A range of PATs are currently available for the agricultural producer but uptake varies by the type of technology and region. Whereas most studies on uptake have focused on US or Australia we empirically examine uptake of machine guidance (MG) and variable rate nitrogen technologies (VRNT) within European farming systems. Using primary information from 971 arable crop growers across five countries: Belgium, Germany, Greece, the Netherlands and the UK, a multilevel random intercept regression estimated a) the differences between adoption and non-adoption and b) the differences between VRNT and MG adoption. We find, aside from size and income differences, which reflect the economic cost barrier to adoption, an attitudinal difference, in terms of optimism towards the technology’s economic return leading to more probability of uptake. Moreover innovative and information seeking behaviour also proved significant when upgrading from machine guidance to variable rate technologies. Subsidy and taxation were considered positive drivers of uptake within the community. However, results suggest that more indirect interventions, such as informational support to counteract industry bias, and demonstration to prove the viability of economic return may be effective at meeting land manager and policy expectations towards PATs.  相似文献   
216.
    
Agriculture sector of Pakistan has traditionally followed an unsustainable path due to degradation of agricultural resources. Therefore, this study was carried out to find environmental, economic and social sustainability of agriculture in Punjab, Sindh, KPK and Balochistan provinces of Pakistan. Based mainly on secondary data, covering the period of 2005/06–2012/13, each dimension of sustainability was analyzed using selected indicators. Crop diversification, soil salinity, and the use of organic and inorganic fertilizers and pesticides were the indicators considered for environmental sustainability analysis. For economic sustainability analysis, change in overall crop production and stability of crop production were the indicators used. Employment of rural labor force and food security were indicators used for social sustainability analysis. The findings from the analyses revealed a tendency towards unsustainable agricultural production in all provinces. This was caused by overuse of inorganic fertilizer, pesticides and groundwater for irrigation in Sindh and Punjab. The lack of sustainable agricultural production in KPK and Balochistan was due to limited use of fertilizer and pesticides in some areas and altogether no use in other areas. Use of groundwater for irrigation in the coastal areas of Balochistan further reinforced agricultural unsustainability. Thus, it was deduced from the findings of this research that there are regional differences in agricultural sustainability in Pakistan. Therefore, it is recommended to formulate effective regional agricultural policies based on local level research and revise agricultural extension structure in order to incorporate need-based services with better dissemination of information and farm level trainings. In addition, broad policy recommendations are made for sustainable agricultural development in each province under the scope of the study.  相似文献   
217.
论矿物元素是地质与农业结合的切入点   总被引:9,自引:0,他引:9  
应用农业地质对比种植的基本方法,对贵州的优质大米、烤烟和茶叶种植与地质环境关系进行研究,总结出优质农产品产量和品质与矿物元素在农产品中的含量成正比,证明矿物营养元素与产品质量有密切关系。而矿物元素来自地质体,本文以矿物元素为纽带,把岩石-土壤-农作物-农产品结合成一个整体,论述矿物元素是地质与农业结合的切入点。  相似文献   
218.
China's macro economy has remained in a good and stable condition overall,experiencing an annual GDP growth of over 10% for several consecutive years.Under this basic condition, the main focus of the Outlook was China's current grain and oil supply,and the demand market with its probable future prices.  相似文献   
219.
    
There is a lack of evidence for impact at scale of vegetable research and development, although the importance of vegetables for human nutrition and smallholder incomes is generally understood. We therefore study adoption and impact of improved tomato and African eggplant varieties developed through international agricultural research, released by national agricultural research and extension systems, and supplied to farmers by private seed companies in East and Southern Africa from 1990 to 2014. The study finds that in 2014, varieties developed by the World Vegetable Center accounted for 50% of tomato and 98% of African eggplant commercial seed production in East and Southern Africa. For Tanzania alone, investment in crop improvement generated economic gains of US$ 255 million for tomato and US$ 5 million for African eggplant up to 2014. The internal rate of return is 26% for tomato and 12% for African eggplant, though we project the latter to increase to 26% by 2024 as the variety was released only in 2007. These findings support the view that agricultural policy and investment reoriented towards contemporary nutritional challenges will give high returns to investment.  相似文献   
220.
    
Standards for carbon accounting are a core element of environmental governance. We study the production of standards as situated and practical action, which is shaped by opportunities, resource constraints, and existing infrastructure. Careful observations of this work reveals what people do and how they organize their actions relevant to the particular questions, conventions, and resources at hand. We apply this practice-centered, ethnomethodological approach to study the creation of an accounting protocol for nitrous oxide emissions from corn production, an effort within the broader project of enlisting agriculture in carbon markets. We find that efforts to create a far-reaching, rigorous, and efficient standard were frustrated by lack of data, contestation of knowledge claims, and the challenges of collapsing real-world heterogeneity into a model and a set of tidy decision rules. In this sense, carbon accounting standards should be understood as provisional, and potentially unstable, compromises.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号