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1.
Motivated by the European sovereign debt crisis, we propose a hybrid sovereign default model that combines an accessible part taking into account the evolution of the sovereign solvency and the impact of critical political events, and a totally inaccessible part for the idiosyncratic credit risk. We obtain closed‐form formulas for the probability that the default occurs at critical political dates in a Markovian setting. Moreover, we introduce a generalized density framework for the hybrid default time and deduce the compensator process of default. Finally, we apply the hybrid model and the generalized density to the valuation of sovereign bonds and explain the significant jumps in long‐term government bond yields during the sovereign crisis.  相似文献   
2.
Advertising situated in environments where people congregate or pass through on their way to somewhere else benefit from being placed in such high traffic areas. However, these strategically placed ads also suffer from conditions of human crowding that prevents them from being noticed and processed. We undertake a study of place-based advertising in a shopping mall using facial recognition software to determine the effect of human density on the attention directed to advertising. We find that as human density increases, attention to advertising decreases, but only to a point where it begins to increase again. Our research also finds that human density plays a moderating role on the motivation to process advertising.  相似文献   
3.
为了研究网架结构的损伤检测方法,根据应变能密度理论,提出采用单元模态应变能密度差值作为网架结构损伤识别指标的方法,以损伤单元模态应变能密度差值的大小初步确定单元的损伤程度。分析了5种具有代表性的损伤工况,并在数值计算结果中引入了白噪声。结果显示,在一阶模态下,针对单损伤、多损伤和轻微损伤、严重损伤等不同损伤工况,损伤杆件的模态应变能密度差值均为高值。因此,该方法可以有效识别出网架结构的损伤位置,根据损伤单元的模态应变能密度差值大小初步确定单元的损伤程度,且在一定的噪声水平下具有较强的鲁棒性,对网架结构损伤识别具有参考价值。  相似文献   
4.
在二进制输入加性高斯白噪声信道下,研究了基于多边缘型低密度奇偶校验码(Multi-edge Low Density Parity Check,MET-LDPC)的密度进化算法。针对高斯近似算法在前期迭代中的不准确问题,提出了一种改进算法。在分析MET-LDPC码的密度进化的基础上,将全密度进化与高斯近似算法结合,通过设置切换限制条件,弥补早期迭代的不准确,提高编码阈值估计的准确性。仿真结果表明,与MET-LDPC全密度进化算法相比,所提算法可以有效提高编码阈值估计的准确性,对LDPC编码的设计有一定的参考价值。  相似文献   
5.
选取2005-2016年285个地级及以上城市数据,利用静态和动态短面板模型分析经济密度和人口规模对环境污染的影响,分析表明:经济密度与环境污染之间存在“倒U型”关系,人口规模扩大会抑制污染物排放;不同等级城市经济密度、不同规模城市人口对环境污染的影响方向一致,但影响程度有所差异;前期污染排放对当期具有正向影响,环境污染物排放存在路径依赖;经济发展水平、工业产值占比和对外开放也是影响污染物排放的重要因素,但各指标对三类污染物排放的影响方向和影响程度存在差异。据此认为,在综合考虑城市具体空间区位条件下,人口适度集聚,提高城市经济密度,优化产业结构以及加强环境监管是环境治理的重要方向。  相似文献   
6.
[目的]研究2006—2016年京津冀城市群土地经济密度的时空格局演变特征及其驱动机制。[方法]以京津冀城市群153个县区为例,运用空间自相关分析、热点分析、地理探测器等研究方法,对土地经济密度的时空演变规律及其驱动因素进行探讨。[结果](1)2006—2016年京津冀城市群县区和地市的土地经济密度及其发展速度在空间上均呈"东高西低,南高北低"格局,但随时间变化区域差异逐渐缩小;(2)Moran′s I指数由0.013 9上升至0.065 3,表明在空间上存在空间集聚状态,且随时间不断优化,区域一体化趋势逐渐增强;(3)空间集聚特征明显,热点显著区集中于北京、天津等经济优势区,并向四周梯度扩散;(4)人均GDP、当年实际使用外资额、固定资产投资额等经济类因子对土地经济密度的解释力较大,且任意两因子交互后作用力优于单项因子作用力。[结论]可为京津冀城市群土地资源的合理利用和差别化调控提供参考。  相似文献   
7.
基于投入产出模型和社会网络分析,利用世界投入产出表相关数据,对2000—2014年中国的增加值贸易进行核算,并分析全球增加值贸易的网络特征。研究结果显示:(1)从出口目的地来看,中国向美国、日本、德国等国家的增加值出口较大;(2)从行业来看,中国的纺织业、除汽车和摩托车之外的其他产品批发业、采矿业等行业的增加值出口较大;(3)根据网络密度的计算结果,世界范围的各国(地区)贸易联系程度在增强;(4)中国的相对点度数和点强度有上升的趋势,而日本和美国有下降的趋势,说明中国在世界增加值贸易格局中的地位在提升,不过美国仍在世界增加值贸易格局中占据主导地位;(5)核心边缘分析结果表明核心国家(地区)的数目经历了先增加后减少的过程,边缘国家(地区)数目则先减少后增加。其中,中国的核心度一直在增加,日本和美国的核心度呈现下降的趋势。因此,为了扩大增加值贸易,增强国际贸易的话语权,中国政府有必要采取调整进出口税率等政策,并重视与美国等国家的双边贸易合作,以实现双赢的结果。  相似文献   
8.
A Cournot collaboration game is complemented with the hypothesis that the cost of R&D collaboration depends on firm’s directed knowledge distance with respect to potential R&D partners. The further hypothesis that directed distance may be non‐uniform and pair‐wise asymmetric reconciles theoretical predictions with qualitative evidence about concentration and multiplicity of components in industrial R&D networks. The welfare properties of sparse stable networks are also affected.  相似文献   
9.
The issue of what to promote in total factor productivity (TFP) in urban areas has been widely discussed in academia and housing prices and population density are confirmed to be two of the most essential driving factors. However, research into the interaction of housing prices and population density with TFP has been neglected, with no previous studies taking spatial factors into consideration, which may bias the results. From this perspective, using spatial panel data models and employing instrumental variables to solve the endogenous problem, this study examines the impact of housing prices on TFP through the mediating effect of population density for 283 Chinese cities during the period 2000–2013, and confirms that the mediating effect accounts for 18.70 % of the total effect. The results show the positive and significant association of housing prices with TFP and the inverted U-shape of population density. The underlying logic is that housing prices change population density by attracting people with high purchasing power and discouraging those unable to afford housing, whereas increased density helps to promote productivity since the settled inhabitants always have highly developed work skills and are well educated. The influencing mechanism of housing prices on TFP through population density is analyzed, namely the spillover effect. We find that the spillover effect exists in the eastern and central regions, as well as first, second, and third tier cities, while for western regions and fifth tier cities, population mobility and increased in housing prices slows their economic development. There is no evidence of any spillover effect in fourth tier cities. A discussion and suggested policy implications are also provided.  相似文献   
10.
This article uses nationally representative household-level panel data from Malawi to estimate how rural population density impacts agricultural intensification and household well-being. We find that areas of higher population density are associated with smaller farm sizes, lower real agricultural wage rates, and higher real maize prices. Any input intensification that occurs seems to be going to increasing maize yields, as we find no evidence that increases in population density enable farmers to increase gross value of crop output per hectare. We also find evidence that households in more densely populated areas increasingly rely on off-farm income to earn a living, but there appears to be a rural population density threshold beyond which households can no longer increase off-farm income per capita.  相似文献   
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