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   27405篇
  免费   1188篇
  国内免费   673篇
财政金融   2109篇
工业经济   1323篇
计划管理   4084篇
经济学   6802篇
综合类   4735篇
运输经济   188篇
旅游经济   340篇
贸易经济   3198篇
农业经济   2291篇
经济概况   4195篇
信息产业经济   1篇
  2024年   89篇
  2023年   384篇
  2022年   454篇
  2021年   621篇
  2020年   782篇
  2019年   589篇
  2018年   529篇
  2017年   679篇
  2016年   726篇
  2015年   917篇
  2014年   1566篇
  2013年   2128篇
  2012年   2419篇
  2011年   2756篇
  2010年   2153篇
  2009年   1875篇
  2008年   2073篇
  2007年   1884篇
  2006年   1732篇
  2005年   1361篇
  2004年   943篇
  2003年   727篇
  2002年   528篇
  2001年   417篇
  2000年   261篇
  1999年   176篇
  1998年   108篇
  1997年   102篇
  1996年   65篇
  1995年   53篇
  1994年   31篇
  1993年   27篇
  1992年   18篇
  1991年   10篇
  1990年   3篇
  1989年   6篇
  1988年   3篇
  1987年   6篇
  1986年   2篇
  1985年   13篇
  1984年   15篇
  1983年   11篇
  1982年   9篇
  1981年   8篇
  1980年   3篇
  1979年   3篇
  1978年   1篇
排序方式: 共有10000条查询结果,搜索用时 937 毫秒
1.
[目的]粮食安全的根本是在耕地,关键在于耕地质量。目前新增耕地主要源于土地开发项目、城乡建设用地增减挂钩土地复垦项目等,这些新增耕地需要对其开展耕地质量等别评定工作,了解新增耕地的质量状况,分析其空间特征,这对落实国家耕地保护制度、开展农村土地整治工作等具有重要作用。[方法]文章以南方典型丘陵区域——江西省宜春市作为研究区域,在新增耕地质量评价的基础上,运用地统计学、景观生态学、Arcgis空间分析技术和典型相关分析方法,研究宜春市新增耕地质量的空间特征,掌握耕地质量等别的分布规律,了解耕地质量的影响因素,为制定合理的耕地资源利用与保护政策提供依据。[结果](1)Moran′s I值结果表明宜春市2014年新增耕地利用质量在空间分布上的空间自相关性最强,而耕地自然质量空间自相关性最弱。(2)景观破碎度指数结果表明优、高等别的新增耕地质量破碎度大于中、低等别的; 多样性指数结果表明新增耕地质量多样性指数比较大; 优势度指数结果表明新增耕地质量等别优势度指数比较小,与多样性指数结果相呼应; 均匀度指数结果表明,新增耕地质量等别均匀度指数相差不大,新增耕地质量等别比较均匀。(3)质心结果表明2013—2014年间宜春市新增耕地质量的格局整体上是向西南方向变化。[结论]宜春市新增耕地质量不高; 新增耕地的利用水平差异性较小,自然本底状况差异较大; 新增耕地质量等别类型多,各质量等别类型耕地均有增加,耕地质量参差不齐,较高等地的新增耕地相对低等地而言更破碎化; 新增耕地的开发格局向着西南方向移动; 该研究为南方丘陵区的新增耕地保护提供了一定的参考依据。  相似文献   
2.
Haze pollution has become a new threat to China's sustainable development, but it may be that local government behaviour can play an important role in the prevention and control of pollutants. A dynamic spatial autoregressive (SAR) model is used to study the relationship between local government competition and haze pollution. To further explore the indirect impact of factor market distortion on haze pollution and control potential endogeneity problems, a newly developed intermediary effect model that incorporates the characteristics of the generalized method of moments (GMM) is utilized to explore how factor market distortion indirectly affects haze pollution. The research results show that regional haze pollution in China is characterized by significant spatial correlation, and local government competition has a positive impact on haze pollution; that is, local government competition exacerbates haze pollution. In general, local government competition not only directly leads to an increase in haze pollution but also further intensifies it by distorting the local factor market, and the intermediary role of factor market distortion is approximately 7.04%. The results of the regional inspection found that competition among local governments in the eastern region did not lead to haze pollution, and distortion of the factor market did not exist as an intermediary effect. However, both direct and intermediary effects are significant in the central and western regions. Therefore, an official performance appraisal system that includes ecological constraints should be established to guide the benign transformation of local government competition, and an environmental management mechanism must be developed for joint prevention and control to reduce haze pollution. In addition, the free flow of factors and marketization are equally important.  相似文献   
3.
We use several U.S. and euro‐area surveys of professional forecasters to estimate a dynamic factor model of inflation featuring time‐varying uncertainty. We obtain survey‐consistent distributions of future inflation at any horizon, both in the U.S. and the euro area. Equipped with this model, we propose a novel measure of the anchoring of inflation expectations that accounts for inflation uncertainty. Our results suggest that following the Great Recession, inflation anchoring improved in the United States, while mild de‐anchoring occurred in the euro area. As of our sample end, both areas appear to be almost equally anchored.  相似文献   
4.
资本外逃是一个复杂的经济问题,是由多种原因造成的,并会给一国经济发展带来不可估量的风险和损失。基于此,论文梳理了资本外逃的研究现状,提出了资本外逃所产生的经济效应,在此基础上,提出了资本外逃的政策选择,为一国在治理资本外逃时提供了政策选择和借鉴。  相似文献   
5.
ABSTRACT

The paper presents a new combined annual cost of living and consumer price index for Norway covering 1492–2018, indicating that Norwegian price history has to be revised. The new historical price index is constructed on a significantly richer data material, which also makes it cover a longer period of price history than the existing one. This is made possible by the compilation of quantitative data from numerous sources, mostly originating from the eighteenth, nineteenth and early twentieth centuries, with grain prices stretching back to 1492. The new combined cost of living and consumer price index is constructed by a Laspeyres approach with shifting baskets for commodities and expenditure groups.

The index makes it possible to follow annual inflation and deflation in Norway for a period of 526 years. When comparing to existing indices, the new series reveals that revisions are needed in Norwegian price history. These make the historical price development more in line with those of the neighbouring countries and more in line with the pattern of wholesale prices.  相似文献   
6.
产业集聚和市场集中是影响区域创新能力的重要因素。本文考察了京津冀、长三角两大经济圈制造业产业集聚与市场集中对区域技术创新能力的作用。实证分析结果表明:两大经济圈制造业集聚与市场集中均在一定程度上促进了区域创新能力的提升,但由于两大区域体制机制条件、创新环境、产业组织形态等不同,制造业产业集聚影响区域技术创新的程度、特征与路径也存在一定差别。两大经济圈应采取差异化集群发展方式,加快推进制造业集群升级,特别是应抢抓第四次工业革命发展机遇,提升制造业智能化水平,提升区域创新能力水平。  相似文献   
7.
The panel data analysis points to economic and social factors contributing to NOx, PM2.5, PM10, SO2, and VOCs in China’s 31 provinces. The spatial correlation analysis using Global and Local Moran’s I values indicates the existence of a significant and positive spatial autocorrelation with respect to environment, economy and energy, and the high spatial correlation is evident in the eastern region, covering the northern part of Yangtze River Delta, Huaihai Economic Zone, and the lower reaches of the Yellow River Economic Belt. The empirical estimation is performed through spatial lag and spatial Durbin models. All emitted air pollutants in 31 provinces have significant spatial dependence and strong spillover effects. There is an inverted U-shaped relationship between emitted air pollutants (NOx, PM10, VOCs, and PM2.5) and per capita GDP, which follows the EKC hypothesis. The relationship between SO2 and per capita GDP does not follow the EKC hypothesis. There is a positive relationship between pollutant emissions and coal consumption, which is consistent with current studies for various countries like Canada, Denmark, UK and US and regions like New York State. However, the effects of science and technology investment on air pollutants are mostly positive, which is not as policy expected.  相似文献   
8.
依据城镇化发展过程中要素空间集聚理论,展开区域经济发展的空间经济结构研究。通过城市引力、克鲁格曼指数计算,比较分析城镇群内部城市吸引力和城市产业分布的差异性,通过人口与生产空间分布集中度指标和不一致系数的测算,分析了山西省城镇群空间要素集聚效应。研究表明,山西省的城镇群规划与要素空间集聚趋势整体一致,城市间产业分工体系基本形成,城镇群的要素集聚效应明显,但人口与生产分布仍存在不一致性。研究认为,山西省城镇群发展应该继续明确各城市的产业分工和特色,引导劳动力和资本要素的合理流动,实现人口与生产空间分布的一致。  相似文献   
9.
10.
In recent decades, agricultural production in the U.S. has continued to shift to large-scale operations, raising concerns about the economic viability of small and midsized farms. To understand whether economies of size provided an incentive for the consolidation of production, the study estimates the total factor productivity (TFP) of five size classes of grain-producing farms in the U.S. Heartland (Corn Belt) region. Using quinquennial Agricultural Census data from 1982 to 2012 the study also compares TFP growth rates across farm sizes to gain insight into whether observed productivity differences are likely to persist. The finding of a strong positive relationship between farm size and TFP suggests that consolidation of production has contributed to recent aggregate productivity growth in the crop sector. The study estimates the extent to which sectoral productivity growth can be attributed to structural change versus other factors including technological change. The study also explores some tradeoffs associated with policies that raise the productivity of small versus large farms.  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