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   3782篇
  免费   117篇
财政金融   671篇
工业经济   212篇
计划管理   612篇
经济学   813篇
综合类   43篇
运输经济   15篇
旅游经济   29篇
贸易经济   590篇
农业经济   181篇
经济概况   732篇
邮电经济   1篇
  2023年   21篇
  2021年   24篇
  2020年   46篇
  2019年   56篇
  2018年   132篇
  2017年   139篇
  2016年   117篇
  2015年   65篇
  2014年   114篇
  2013年   396篇
  2012年   138篇
  2011年   131篇
  2010年   141篇
  2009年   157篇
  2008年   137篇
  2007年   139篇
  2006年   113篇
  2005年   65篇
  2004年   89篇
  2003年   80篇
  2002年   68篇
  2001年   47篇
  2000年   68篇
  1999年   48篇
  1998年   65篇
  1997年   31篇
  1996年   59篇
  1995年   40篇
  1994年   50篇
  1993年   47篇
  1992年   54篇
  1991年   52篇
  1990年   57篇
  1989年   28篇
  1988年   31篇
  1987年   41篇
  1986年   39篇
  1985年   60篇
  1984年   56篇
  1983年   35篇
  1982年   43篇
  1981年   45篇
  1980年   41篇
  1979年   43篇
  1978年   48篇
  1977年   47篇
  1976年   42篇
  1975年   30篇
  1974年   22篇
  1969年   25篇
排序方式: 共有3899条查询结果,搜索用时 31 毫秒
151.
In this article, the potential impacts of Bt eggplant technology in Indian agriculture are analyzed. Several proprietary Bt hybrids are likely to be commercialized in the near future. Based on field trial data, it is shown that the technology can significantly reduce insecticide applications and increase effective yields. Comprehensive farm-survey data are used to project farm-level effects and future adoption rates. Simulations show that the aggregate economic surplus gains of Bt hybrids could be around US$108 million per year. Consumers will capture a large share of these gains, but farmers and the innovating company will benefit too. As the company has also shared its technology with the public sector, Bt open-pollinated varieties might become available with a certain time lag. This would make the technology more accessible, especially for resource-poor farmers, entailing further improvements in welfare and distribution effects. The wider implications of the private–public technology transfer are discussed. Furthermore, the potential benefits for farmers' health resulting from reduced insecticide applications are examined, using an econometric model and a cost-of-illness approach. These benefits are worth an additional $3–4 million per year, yet they constitute only a small fraction of the technology's environmental and health externalities. More research is needed for comprehensive impact analysis.  相似文献   
152.
Growth and liberalization of world trade have increased the risks of introduction of quarantine plant pests into importing countries. Import inspection of incoming commodities is a major tool for prevention of pest introductions related to world trade, but inspection capacities are limited. This article develops a theoretical and an empirical model for the optimal allocation of inspection effort for phytosanitary inspection of imported commodities when the inspecting agency has a limited capacity. It is shown that the optimal allocation of inspection effort equalizes marginal costs of pest introduction across risky commodity pathways. The numerical illustration finds the optimal allocation of inspection effort of chrysanthemum cuttings imported in the Netherlands. The numerical results suggest that ceteris paribus , greater inspection effort should be allocated to pathways whose inspection yields a greater reduction in the expected costs of pest introduction. The numerical results also suggest that import inspection has a high marginal benefit. In particular, we found that each additional euro of the inspection capacity decreases the expected costs of pest introduction from 18 to 49 euros, depending on the initial inspection capacity.  相似文献   
153.
Governments around the world are beginning to embrace a new form of environmental regulation – mandatory disclosure of information. While information disclosure programs appear to have an impact on subsequent firm behavior – often resulting in lower levels of pollution – little is known about the costs and benefits of these programs and whether or not they enhance social welfare. This paper presents a simple bargaining model where mandatory information disclosure is used to overcome a lack of information on the part of the public. We characterize the conditions under which information disclosure will lead to a reduction in emissions, and ultimately, the conditions under which it will enhance social welfare. Several extensions of the model are briefly explored, including the effect of two sources of pollution – only one of which is subject to information disclosure. This paper was prepared while V. Santhakumar was a Visiting Scholar at the Vanderbilt Center for Environmental Management Studies, Vanderbilt University.  相似文献   
154.
We examine the effect of ownership structure on firm performance, for firms listed on Vietnamese stock exchanges, using 2744 firm‐year observations over the period from 2007 to 2012. We find a non‐linear relationship between ownership structure and firm performance. State ownership has a convex relationship with firm performance. This paper finds that firm performance increases beyond 28.67 percent level of state ownership. Foreign ownership has a concave relationship with firm performance. We find that firm performance increases with an increase of foreign ownership up to a level of 43 percent and then decreases. Policy makers should encourage foreign ownership and widely dispersed state ownership in firms, which can help improve firm performance.  相似文献   
155.
This article defines the marketing concept in a traditional way, but extends its application to high-technology products. Dennis Cahill, Sharon Thach, and Robert Warshawsky present two case studies of high-technology products. Both products were ultimately market failures; however, the analysis presents one as a successful application of the marketing concept, contrasting sharply with the other.  相似文献   
156.
This article assembles the results of three multicountry surveys on variety performance and adoption patterns to measure the impacts of maize research in West and Central Africa from 1981 to 2005, and uses cost data since 1971 to compute social rates of return on public investments in maize research in the region. Adoption of modern varieties increased from less than 5% of the maize area in the 1970s to about 60% in 2005, yielding an aggregate rate of return on research and development (R&D) investment of 43%. The estimated number of people moved out of poverty through adoption of new maize varieties rose gradually in the 1980s to more than one million people per year since the mid 1990s. Over half of these impacts can be attributed to international maize research at IITA and CIMMYT. The article concludes with a discussion of strategic options to enhance the impacts of maize research in the region.  相似文献   
157.
158.
Abstract: Oversight agencies in the water sector emphasize performance monitoring based on outputs, such as customers served, volume delivered, and service quality. However, bureaucratic tendencies can curtail operational innovation and creativity. In situations where managers lack full operating knowledge and capacities, proactive and consultative monitoring and regulation can yield benefits. This study reviews the results of Uganda's National Water and Sewerage Corporation's (NWSC) approach to performance monitoring (and ‘self‐regulation’). The purpose of this study is to outline corrective actions undertaken by the NWSC Management and Staff to turn around performance, the sequencing of those steps, and the outcomes from this reform program. The NWSC focuses on promoting improvements in technical processes and input selection. Improvements in service quality and network expansion resulted from aligning performance improvement initiatives with the organization's financial performance and team development. The program's success required managing organizational rigidities and moving towards full cost‐recovery. In particular, organizational incentives and information flows encouraged managers to reduce rules and procedures that hindered strong performance. African proverbs are interspersed throughout the article to underscore key themes and lessons for those designing, implementing, and evaluating infrastructure sector reform initiatives.  相似文献   
159.
In Sub-Saharan Africa, fish ponds are often an integral part of farming systems but have suffered from a lack of viability and sustainability. The present study aims to understand the strategies used by fish farmers to overcome economic and environmental constraints. In 2008 and 2009, fish farmers were surveyed in Central and Western Cameroon, and the fish production systems were classified by cluster analysis. Four broad types were identified according to the complexity of household operations. The development of extensive systems (large-scale and low-input) in rural areas of central Cameroon is induced mainly by abundant available land. For semi-intensive systems in both regions (small-scale and high-input in the Western Region, large-scale and high-input in peri-urban areas of the Central Region), horizontal integration is not sufficient to make fish production profitable and sustainable. More intensive fish farms tend towards vertical integration, in which farmers establish close links with input suppliers. Main causes of low productivity of semi-intensive systems (1–2?t/ha/yr) are both lack of knowledge of fish farming principles by farmers and lack of technical improvement by extension agents and researchers which need to consider the local complexity of farming systems to develop and intensify fish production. The adaptation of development strategies to socio-economic and environmental contexts is a necessity to hope for an increase in fish pond aquaculture production in Africa.  相似文献   
160.
This article examines the ecosystem impacts of transgenic Bt cotton technology resulting from reduced chemical pesticide use. Employing unique panel data from smallholder farmers in India, negative environmental and health effects of pesticide use are quantified with the environmental impact quotient (EIQ), with and without Bt technology. An environmentally sensitive dynamic production function is estimated, treating the environmental risk of pesticide toxicity as an undesirable output in the production process. Negative externalities are significantly lower in Bt than in conventional cotton. The reduction in EIQ through Bt technology adoption has increased from 39 per cent during 2002–2004 to 68 per cent during 2006–2008. Bt adoption has also contributed to higher environmental efficiency. Environmental efficiency is influenced by the quality of Bt technology: high‐quality Bt seeds are associated with higher environmental efficiency than lower‐quality seeds.  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