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   1511篇
  免费   87篇
  国内免费   26篇
财政金融   147篇
工业经济   117篇
计划管理   320篇
经济学   437篇
综合类   63篇
运输经济   21篇
旅游经济   27篇
贸易经济   147篇
农业经济   183篇
经济概况   162篇
  2024年   7篇
  2023年   39篇
  2022年   51篇
  2021年   56篇
  2020年   88篇
  2019年   66篇
  2018年   51篇
  2017年   62篇
  2016年   57篇
  2015年   61篇
  2014年   104篇
  2013年   176篇
  2012年   93篇
  2011年   103篇
  2010年   66篇
  2009年   70篇
  2008年   84篇
  2007年   74篇
  2006年   70篇
  2005年   38篇
  2004年   29篇
  2003年   33篇
  2002年   28篇
  2001年   23篇
  2000年   16篇
  1999年   28篇
  1998年   12篇
  1997年   11篇
  1996年   5篇
  1995年   8篇
  1994年   7篇
  1993年   3篇
  1992年   2篇
  1988年   1篇
  1986年   2篇
排序方式: 共有1624条查询结果,搜索用时 197 毫秒
51.
土地是最基础与最重要的资源与资产,是国家经济政策拟定的依据,是实施规划纲要与落实方针政策的基础。土地是人类生存的基础,而且是不可再生的,只有加大土地管理的力度,高效合理地利用土地,才能实现我国可持续发展的目标。地籍管理是土地管理工作的重点领域,是土地产权得到保障的前提。目前的土地管理集中在对土地产权的管理,土地产权变化会涉及到地理实体时间、空间及属性的变化,时态GIS正好反映了此变化。目前时态GIS的研究集中在对时空数据模型的建构。时空数据模型决定了时态GIS系统的运行效率。无论是国内还是国外均对时空数据模型进行了研究,通过模型的构建的相应地提出了超过20种模型,而在实际的应用中,不同的模型有不同的特点。文章对典型的6种时空数据模型进行了分析,从模型的建模思路出发,分别探讨了模型的适合环境与优缺点,可以为人们在应用时空数据模型进行土地管理时提供帮助,有利于研究者对模型的进一步研究。  相似文献   
52.
[目的]恶劣的生态环境和有限的资源驱动着新疆特殊生态系统服务的形成,人类又通过对生态系统服务的消费来满足和提高自身福祉,需要研究其时空变化并辨识主要驱动因素,支持区域可持续发展。[方法]文章构建了融合不同土地利用类型生态系统服务的价值量排序及服务功能强度矩阵的生态系统服务评估体系,并耦合3种关键驱动因子以评估各个因子的驱动强度,实现对生态系统服务热点与冷点变化的驱动及迁移分析。[结果]2000—2010年全疆生态系统服务总体增加,这一时期生态系统服务的热点区大部分转变为2010—2015年的冷点区,且15年来生态系统服务总体呈现小幅下降趋势。3个时期北疆和南疆人为干扰强度均呈增加趋势,由其驱动的生态系统服务则相应减小;南疆地区植被覆盖范围极其有限,故对生态系统服务驱动强度低;降水在北疆和南疆都能够产生高生态系统服务,但降水量的不稳定性能够使生态系统服务产生较大波动。相比于南疆地区,北疆生态系统在外界干扰下能够体现出更强的抗性和整体性,从而实现相对高效的生态系统服务输出。[结论]对关键驱动因子作用下的生态系统服务进行时空变化分析,有助于理解当地生态系统产生变化的原因,从而为当地生态环境保护提供参考。  相似文献   
53.
Bogotá and the 17 neighboring municipalities make up one of the biggest metropolitan areas in Latin America. However, despite strong functional interactions within the area, there is no official government body at this level in charge of coordinating authorities and providing solutions to the wide variety of issues arising in the regional urban land system. Aiming at providing an insight on future land-use developments linked to new transport infrastructures and at offering a tool to support territorial decision-making, this paper presents a cellular automata-based (CA) model based in Metronamica® software, that allows testing different scenarios based on potential land-use policies, environmental suitability and transport alternatives.There has not been, so far, an urban planning tool that accounts for the complexities of this region. CA-based land-use simulations constitute a useful approach to understanding the impacts of urban planning policies and regulations. This tool can help to improve inter-territorial and inter-institutional coordination, which through planning and management policies seek a spatially integrated development, with a long-term perspective.The CA-based model proposed was calibrated to reproduce land-use changes between 2007 and 2016 using different methods and indicators. The model was used to simulate and analyze eight scenarios with different policy directions of transport infrastructure in the future of the region. The results of the simulations reflect the dynamics of territorial occupation. The calibration indices in the experiment indicate a high degree of suitability for the CA Bogotá model, proving its effectiveness and potential as a useful tool for decision-making. The results show that occupation scenarios with restricted developable zones within the city, tend to have the greater dispersion rate in the study area, compared to scenarios where land development plans are promoted in Bogotá, which representing a more compact development.  相似文献   
54.
This paper shows that oil shocks impact economic growth primarily through the conditional variance of growth. Our comparison of models focuses on density forecasts. Over a range of dynamic models, oil shock measures and data, we find a robust link between oil shocks and the volatility of economic growth. We then develop a new measure of oil shocks and show that it is superior to existing measures; it indicates that the conditional variance of growth increases in response to an indicator of the local maximum oil price exceedance. The empirical results uncover a large pronounced asymmetric response of the growth volatility to oil price changes. The uncertainty about future growth is considerably lower than with a benchmark AR(1) model when no oil shocks are present.  相似文献   
55.
We study the contribution of money to business‐cycle fluctuations in the United States, the United Kingdom, Japan, and the euro area using a small‐scale structural monetary business cycle model. Constrained likelihood‐based estimates of the parameters are provided and time instabilities analyzed. Real balances are statistically important for output and inflation fluctuations. Their contribution changes over time. Models giving money no role provide a distorted representation of the sources of cyclical fluctuations, of the transmission of shocks, and of the events of the last 40 years.  相似文献   
56.
This study reports the results of an experiment on directed networks with positive externalities induced by cost-sharing. Subjects participated in a network game in which they had to choose between private and public transportations. If a player chose public transportation, then she shared the travel cost equally with other players making the same choice, whereas if she chose private transportation, then her travel cost was fixed. Travel costs on the private route were manipulated across the two experimental conditions. In one condition, these costs were homogeneous among players; in the other condition, they were heterogeneous among players and only privately known. We found that half (none) of the player groups in the homogeneous (heterogeneous) condition converged toward the efficient equilibrium. Examination of the system dynamics shows that convergence toward efficiency was facilitated by: (1) the existence of an intermediate equilibrium choice; and (2) strategic teaching by which a farsighted player chooses strategies with poor short-term payoff in order to shift group decisions to the efficient equilibrium and thereby increase her own long-term benefit.  相似文献   
57.
We study the effect of tenure on earnings instability in Italy using the reforms of temporary employment contracts, which affected the average tenure of workers differentially across cohorts. We develop a model of earnings dynamics, and we exploit the variation of tenure and instability over time and across birth cohorts to estimate policy‐relevant parameters. Our results indicate that each year of tenure on the job reduces earnings instability by 11 percent; the drop is faster in the first three years of the match. Workers on a temporary contract have an earnings instability up to 100 percent higher than workers on a permanent contract.  相似文献   
58.
Based on the business environmental literature and system dynamics, this paper develops a simulation model for managing the business risks derived from climate change. In particular, the purpose of this paper is to transform the valuable findings from the literature regarding climate change and corporate implications into an effective business management model with a broad applicability, regardless of the size of the business or the sector in which it operates. A methodology consistent with the basic principles of the system dynamic modeling process is developed, and a case study is designed to determine the level of completeness of the simulation model and its ability to address different aspects of business performance. To do so, three different scenarios have been simulated to analyze the reactive, proactive and inactive stance of managers against climate change risks. Copyright © 2017 John Wiley & Sons, Ltd and ERP Environment  相似文献   
59.
研究目的:分析城市扩展中交通用地、商住用地和工业用地扩张的时序特征、空间关系以及扩张时点的影响因素。研究方法:农地—建设用地转换最优时机理论;加速失效模型。研究结果:(1)不同类型建设用地在扩张过程中具有相互关联的时序和空间特征;(2)静海区交通用地引导了其他建设用地扩张的方向,而不同级别交通用地由于对建设用地和农用地影响的差异,加快或延缓了建设用地扩张的时机;(3)商住和工业用地在200— 400 m 范围内相互集聚,且商住用地产生的集聚效应强于工业用地。研究结论:细化建设用地类型以分析城市扩张的特征和机制,有助于城市扩展区的布局优化和集约发展。  相似文献   
60.
Current trends in the development and innovation of information technologies and shorter life cycles of electronic products have resulted in the generation of large amounts of waste (e-waste) which can potentially cause environmental problems due to the toxicity of some of their components. The e-waste problematic has attracted the attention of governments, companies and consumers that look to identify strategies for the management and proper disposal of e-waste with the goal to protect the environment. This work uses the methodology of system dynamics to simulate how the rate of products returned by individuals and the amount of computers recovered in an open-loop reverse supply chain, varies under different scenarios. The simulated scenarios correspond to the possible combinations of five macro factors: rate of innovation and product life cycle, information available to consumers about e-waste recycling, legislation, e-waste programs structure along with diffusion and publicity efforts. The results of the simulation are relevant to identify over which factors it is convenient to intervene to increase the amount of recycled computers because this amount represents a reduction in the volume of e-waste and an enterprise opportunity to generate earnings from recycling computers.  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