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   1822篇
  免费   139篇
  国内免费   24篇
财政金融   201篇
工业经济   116篇
计划管理   501篇
经济学   333篇
综合类   194篇
运输经济   14篇
旅游经济   15篇
贸易经济   327篇
农业经济   106篇
经济概况   178篇
  2024年   5篇
  2023年   30篇
  2022年   26篇
  2021年   34篇
  2020年   40篇
  2019年   47篇
  2018年   47篇
  2017年   49篇
  2016年   49篇
  2015年   78篇
  2014年   165篇
  2013年   160篇
  2012年   167篇
  2011年   157篇
  2010年   151篇
  2009年   113篇
  2008年   112篇
  2007年   108篇
  2006年   88篇
  2005年   66篇
  2004年   51篇
  2003年   41篇
  2002年   39篇
  2001年   27篇
  2000年   26篇
  1999年   22篇
  1998年   22篇
  1997年   15篇
  1996年   11篇
  1995年   4篇
  1994年   3篇
  1993年   6篇
  1992年   6篇
  1991年   9篇
  1990年   5篇
  1989年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
排序方式: 共有1985条查询结果,搜索用时 218 毫秒
41.
This paper begins by presenting a simple model of the way in which experts estimate probabilities. The model is then used to construct a likelihood-based aggregation formula for combining multiple probability forecasts. The resulting aggregator has a simple analytical form that depends on a single, easily-interpretable parameter. This makes it computationally simple, attractive for further development, and robust against overfitting. Based on a large-scale dataset in which over 1300 experts tried to predict 69 geopolitical events, our aggregator is found to be superior to several widely-used aggregation algorithms.  相似文献   
42.
水利工程是国民经济建设过程中非常重要的建设内容,能够为人们的生产生活提供极大的便利,这就需要保证水利工程测量工作的准确性。在水利工程测量过程中,常用的测量工具就是全站仪,做好其误差分析与精度控制工作是非常必要的,本文就主要针对此予以简单分析。  相似文献   
43.
In this study we present a simple mechanism in a many-to-one matching market where multiple costless applications are allowed. The mechanism is based on the principles of eligibility and priority and it implements the set of stable matchings in Subgame Perfect Nash Equilibrium. We extend the analysis to a symmetric mechanism where colleges and students interchange their roles. This mechanism also implements the set of stable matchings.  相似文献   
44.
Beginning in the early 1990’s, grazing lands once held in common were contracted to individual households in the rangeland regions of China. The resulting fragmentation of rangelands has led to ecological and social problems. As China seeks to address intractable poverty and rangeland degradation, attention has turned to rental, or transfer, of contracted grazing land as a market-based approach to re-aggregating grazing land into larger units that support economies of scale. However, given that many pastoral regions still maintain community customary institutions, what the relationship between market mechanisms and local customary institutions should be in rangeland management needs further analysis. This paper applies comparative case studies of two types of relationships between market mechanisms and customary institutions: (1) market mechanisms that replace customary institutions in the case of Axi village, and (2) market mechanisms that are embedded within customary institutions in Xiareer village. This allows contrast of the impacts of differing approaches on livelihoods, livestock production, and wealth differentiation among pastoral households. We found that there is a higher level of livestock mortality, lower livestock productivity, and higher livestock production cost in Axi Village compared to Xiareer Village. In addition, household asset levels are higher and there is less income differentiation in Xiareer Village. It is concluded that embedding market mechanisms within customary institutions has had notable benefits for the herders of Xiareer Village, because it is a better fit to the coupled pastoral social-ecological system. Based on these findings, we argue that in pastoral communities where the rangeland transfer system for contracted grazing land has not yet been implemented, it is critical to reconsider China’s current policy approach to pay greater attention to the innovative management systems being developed in local regions. Instead of considering market-based approaches as oppositional to traditional institutions, options that derive from the interaction of market-based and customary institutions should be considered.  相似文献   
45.
Many developing countries face a major challenge today: how to safeguard the biodiversity maintained in the fields of the rural poor - which constitute a national and global public good - whilst meeting those same people's development needs and rights? A solution to this dilemma has thus been sought in adapting the design and implementation of Payments for Ecosystem Services (PES) concepts to the conservation of agrobiodiversity.Here we review the application of nine such Payments for Agrobiodiversity Conservation (PACS) schemes that have been applied to date in four Latin American countries over the period 2010–2018. These covered 130 threatened varieties across a number of major food crops, and involved over 100 farming communities and 1,100 farmers (45 % of which were women). Conservation service offers were received through a competitive tender mechanism. Average bid offers revealed high heterogeneity, varying between US$675/ha. to ten times as much.In relation to issues identified as key to PES, such as spatial targeting, differentiated payments and conditionality, the underlying design of the PACS schemes may be considered solid. PACS-related prioritisation processes allow for the a priori identification of sites with high ecosystem service densities and high threat levels. The use of competitive tenders permits accounting for cost heterogeneity in the provision of conservation services and for payments to be differentiated. Conditionality is strong.In terms of implementation, a “back of the envelope” calculation based on the results of the competitive tenders suggests that conservation costs are modest. For a priority conservation portfolio of 100 varieties (which may be from different crops) each with a target area of five hectares, costs would amount to just under US$860,000 over twenty years or US$70,000 p.a. at a 5 % discount rate. The small-scale and one-off nature of the interventions realised to date, along with threatened crop variety seed availability constraints, have however meant that environmental effectiveness has been incomplete in the short-term (area cultivated with specific threatened varieties increased, but still below the “not at risk” threshold). The establishment of systematic monitoring systems is required to determine longer-term impacts and inform more regular PACS interventions within a dynamically evolving systems context.  相似文献   
46.
This paper studies the transmission of bank capital shocks to loan supply in Indonesia. Using bank data for the period 2001:Q1 to 2018:Q4, we estimate dynamic panel data models of bank lending. We find nonlinear effects of capital on loan growth. Specifically, the response of weakly capitalized banks to changes in their capital positions is larger than that of strongly capitalized banks. This non-linearity implies that not only the level of capital but also its distribution across banks in the system affects the transmission of shocks to aggregate lending. Likewise, the effects of bank recapitalization on loan growth depend on banks’ starting capital positions and the size and distribution of capital injections.  相似文献   
47.
This paper contributes to the IB literature by investigating MNEs’ risk mitigation strategies in emerging markets. Drawing on institutional perspectives and March’s theoretical concept of forming a ‘political coalition’, we propose that risk mitigation cannot be limited to passive compliance and/or demonstrating good corporate behavior, but should extend to collective efforts by building a political coalition and working with key stakeholders to manage potential risk and obtain favorable outcomes in complex institutional environments. In considering MNEs in contemporary China and India, we offer different types of risk mitigation strategies under various institutional contexts and a framework for future research.  相似文献   
48.
In this study, we employ a multivariate panel error correction model (PVECM) to investigate asymmetric price transmission among the farm, processor, and retail segments of the European food supply chain for the 2005–2016 period. The results indicate that, in both the long- and short-run, retail prices respond more strongly to processor price increases than decreases and the same occurs for processor prices due to farm price changes. Thus, the findings demonstrate the presence of positive asymmetric price transmission in the European food supply chain. Finally, the results of the present study indicate that the food price pass-through varies greatly across product category and across countries, and that the pass-through to producer prices is greater than that to consumer prices.  相似文献   
49.
高速移动环境下,无线信道具有时频双选性衰落的特性,使得滤波器组多载波(Filter Bank Multi-carrier,FBMC)系统产生长突发差错。将一种基于Baker映射的混沌交织算法应用在滤波器组多载波系统中,根据混沌密钥对发送数据进行分块和重新排列,按照Baker映射规则完成数据交织。此方法可以将长突发差错变为单突发差错,结合卷积编码能有效地纠正双选信道产生的长突发差错。仿真结果表明,在双选择信道中,基于混沌交织的滤波器组多载波系统误比特率性能优于传统基于块交织的滤波器组多载波系统。  相似文献   
50.
贾圆 《价值工程》2014,(24):21-22
通过对带式输送机安装中心轴线标定方法进行理论分析,推导出边长和角度实测的精度相关公式,同时输送机的施工安装工艺对测量标定中心轴线提出了较高的要求,为我们提出了在实际工作中的具体做法和应注意的几个问题。  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