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   1753篇
  免费   20篇
  国内免费   1篇
财政金融   317篇
工业经济   20篇
计划管理   563篇
经济学   293篇
综合类   4篇
运输经济   59篇
旅游经济   116篇
贸易经济   296篇
农业经济   42篇
经济概况   64篇
  2024年   8篇
  2023年   72篇
  2022年   25篇
  2021年   45篇
  2020年   102篇
  2019年   97篇
  2018年   157篇
  2017年   158篇
  2016年   179篇
  2015年   86篇
  2014年   148篇
  2013年   469篇
  2012年   41篇
  2011年   20篇
  2010年   19篇
  2009年   13篇
  2008年   12篇
  2007年   14篇
  2006年   13篇
  2005年   9篇
  2004年   7篇
  2003年   4篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1999年   8篇
  1998年   6篇
  1997年   9篇
  1996年   8篇
  1995年   17篇
  1994年   13篇
  1993年   1篇
  1988年   1篇
  1985年   4篇
  1984年   1篇
  1982年   2篇
  1980年   1篇
  1979年   1篇
排序方式: 共有1774条查询结果,搜索用时 15 毫秒
101.
Environmental multi-regional input–output (MRIO) models require large amounts of data that all have their specific uncertainties. This paper presents a sensitivity and uncertainty analysis in order to gain an understanding of the directions in which efforts should be made to reduce these uncertainties. The analyses were carried out for an MRIO model to calculate the Dutch carbon footprint. A sensitivity analysis of the technical coefficients showed that changes in the coefficients in the domestic blocks and in the Dutch import blocks had the largest effects on the calculated footprint. The uncertainty analysis consisting of a Monte Carlo simulation based on probability distributions around the model coefficients showed a relatively low degree of uncertainty in the total Dutch carbon footprint; uncertainties in the carbon emissions allocated to regions, sectors and products were larger. Both analyses showed that, in certain cases, it is justified to apply a partial MRIO analysis.  相似文献   
102.
Outsourcing and trade integration of advanced countries is debated with respect to employment effects, in particular for low educated workers – at least in relative terms. We study the employment effects – differentiated by educational attainment levels – of changes in the patterns of trade integration and outsourcing in the Austrian economy over the periods 1995–2000 and 2000–2005 using hierarchical decomposition analysis based on deflated input–output tables. Outsourcing is modeled as changes in the shares of domestically produced intermediates in total intermediates. A similar decomposition of the final demand vector allows us to draw conclusions on the overall employment effects of trade integration. The results suggest that the expected negative employment effects of outsourcing and rising import penetration have been overcompensated by increasing exports. Thus, the overall employment effects of Austrian trade integration have been positive for all educational attainment groups. However, whereas the total effects have been strongest for medium and high educated workers over the period 1995–2000, employment of low educated workers have been strongest and positively affected over the period 2000–2005. This pattern can be explained by a more sluggish export performance together with stronger negative effects of outsourcing and import penetration in medium and high-skill intensive products.  相似文献   
103.
104.
提出了一种基于迭代FFT算法的优化方法来实现平面稀疏阵列的峰值旁瓣电平优化 ,并给出了详细的优化步骤。在给定的旁瓣约束条件下,利用阵列因子与阵元激励之间存在 的傅里叶变换关系,对不同的初始随机阵元激励分别进行迭代循环,就可以降低稀疏阵列的 旁瓣电平。在迭代过程中,根据稀疏率将阵元激励按幅度大小置1置0来完成阵列稀疏。仿真 实验证明了该方法的高效性和稳健性。  相似文献   
105.
Abstract

Progressive changes in mean annual temperatures are arguably the strongest evidence of ongoing climate change. In destinations with a Mediterranean climate, in contrast to the colder months, during summer, rising air temperatures are believed to inhibit tourist movements and activities, and consequently affect tourists’ evaluation of and satisfaction with their experiences. To the best of our knowledge, no previous study has investigated the potential impact of climate change on tourists’ time–space activity using actual behavioural tracking-based information. Data collected via GPS technology and a post-visit survey of tourists (n = 404) visiting Lisbon during the summer were analysed via structural equation modelling (PLS-SEM). The results report empirical evidence of the present impact of (summer) weather on urban tourists’ time–space activity and on their intra-destination experience evaluation. Specifically, maximum air temperature is found to have a significant negative effect on overall satisfaction, while the meteorological conditions of the entire day reveal a significant impact on tourists’ activities and movements. The results are particularly useful for the sustainable adaptive management of urban attractions and destinations that are especially vulnerable to climate change, as well as in managing its adverse impact on tourists’ experiences.  相似文献   
106.
Health care public–private partnerships (PPPs), where clinical services as well as infrastructure are delivered by the private sector, are coming under the spotlight as governments seek to achieve value for money in health budgets. Existing examples have been widely reported as successful. However, this article urges caution as a closer look at the evidence shows that handing over control of service delivery to the private sector is difficult to monitor and evaluate, carries cost implications which remain largely unquantified and can create additional risk.  相似文献   
107.
In the marginal, upland regions of the Philippines, soil erosion and poverty are significant problems. The Landcare Programme has sought to address these twin problems. We assess the economic impacts of the Landcare Programme in the Province of Bohol. We first explore whether the adoption of Landcare practices, particularly those of contour farming and tree planting, in a highly degraded landscape has resulted in improved livelihood outcomes for upland farming families. Second, we analyse the potential for the piecemeal adoption of these measures to deliver tangible benefits at the watershed scale. Finally, using a benefit–cost approach, these outcomes are compared with the costs of research and extension projects that have helped achieve them. We conclude that the net economic impact of the Landcare Programme in Bohol is positive, with the primary beneficiaries being the individual households that adopt the Landcare practices. These benefits are largely generated by productive opportunities that arise once the hillsides have been stabilized. Although the downstream impacts of land-use changes associated with the Landcare Programme are positive, they are of marginal economic importance. Hence, the focus and primary justification of the Landcare Programme should be on improving the productivity and livelihoods of upland farming households.  相似文献   
108.
Recognizing the socio-economic and biophysical causes of land degradation at the national level is important for cause-targeted strategies when designing policies for combating land degradation. This study aims to identify the biophysical and socio-economic factors that significantly affect land degradation across Vietnam and to interpret the causalities underlying the effects. The dependent variables considered in the study are spatial, the extent and intensity of degradation in three land-use zones (agriculture, forest and severely degraded abandonment). The hypothesized explanatory variables are common economic and demographic drivers and bio-physical factors such as soil, terrain constraints, and neighborhood land-use structures that are often neglected in many large-scale land degradation assessments. Instead of using a single inferential statistic technique, we used multi-linear regression and binary logistic regression in a complementary manner to increase the detectability and credibility of the degradation cause analyses. The results showed agricultural production growth had strong and consistent effects on land degradation extent and intensity. Population growth, especially in rural areas, had a strong effect on the extent of overall land degradation. The importance of a neighboring forest was revealed for its ability to reduce land degradation intensity in abandoned, unproductive lands. The concrete faceting of the causal analysis for each land-use zone as social–ecological stratum allowed us to combine the defined social–ecological contexts, contemporary theories, and hypotheses in the field to clarify the causal factors of a complex phenomenon like land degradation. The study demonstrates these contemporary inferential statistics can be complementarily used to sufficiently detect and understand land degradation causes at the national level. The results suggest implications for national land management policy: internalizing land degradation costs in the farming system evaluation for payment for ecosystem services policy, restricting forest conversion, and improving extension services and education in agrarian communities.  相似文献   
109.
The rural–urban interface is the place of transition between that which we call “urban” and that which we call “rural.” The interface is situated between two places perceived to be different, but which are indelibly linked. Although the functional differences between “rural” and “urban” people (or those seen as “been-heres” versus “come-heres”) seem to be diminishing, differing perspectives and preferences persist along the rural–urban edge. Such differences influence the way that land users, decision makers, and the community manage the environment and react to landscape change. Using a comparative case study in Calaveras County, California, I examine the differences and similarities between “been-heres” and “come-heres” along several lines: basic demographic characteristics, political party affiliations and ideologies, and conceptions of private property rights, concluding that the dichotomy is false but instructive. The been-here/come-here divide, rather than being a definitive means for characterizing stakeholders or predicting their behavior or perspectives, serves as a heuristic for understanding the starting places of certain actors. Furthermore, this kind of analysis reveals not only where and how people and perspectives contrast but also the ways that they converge. Improving our understandings differing people and perspectives is especially important as decision-makers struggle to plan for and manage livable places and sustainable environments among groups with varying preferences which may sometimes conflict.  相似文献   
110.
磁共振成像技术已经成为现代临床医学影像检查的重要手段之一,而传统的成像手段的主要缺点是其成像速度太慢。文章主要阐述了半傅里叶成像、平行成像以及压缩传感成像的基本原理,从而展现MR快速成像技术巨大的应用价值和研究价值。  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