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   860篇
  免费   12篇
财政金融   252篇
工业经济   48篇
计划管理   140篇
经济学   173篇
综合类   30篇
运输经济   8篇
旅游经济   9篇
贸易经济   83篇
农业经济   34篇
经济概况   95篇
  2023年   18篇
  2022年   17篇
  2021年   38篇
  2020年   48篇
  2019年   32篇
  2018年   19篇
  2017年   54篇
  2016年   39篇
  2015年   23篇
  2014年   45篇
  2013年   47篇
  2012年   56篇
  2011年   85篇
  2010年   48篇
  2009年   44篇
  2008年   62篇
  2007年   43篇
  2006年   35篇
  2005年   21篇
  2004年   12篇
  2003年   14篇
  2002年   20篇
  2001年   7篇
  2000年   9篇
  1999年   7篇
  1998年   9篇
  1997年   7篇
  1996年   2篇
  1994年   1篇
  1993年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1984年   3篇
  1983年   2篇
排序方式: 共有872条查询结果,搜索用时 250 毫秒
31.
32.
The role of futures contracts on spot prices has been one of the key focus areas of research since the recent surge in commodity prices and increase in the volatility of commodity returns. However, no consensus arises from this literature, and hence it is difficult to link the use of futures contracts in agricultural commodities by non-hedgers and the growing food insecurity within developing countries. The purpose of this paper is to highlight causal relationships from futures contracts to spot prices of underlying assets, namely agricultural commodities. As research that focus on exchange-traded funds do not provide any clear conclusions, we focus on the imbalance between short- and long-open positions, this imbalance being caused by the exchange traded funds’ participation in futures markets. In this paper, we estimate relationships between financial variables including indicators for speculation in futures markets and the returns of cocoa, corn, soybean, wheat, coffee, rice, and sugar on a weekly basis from 1998 to 2013. Significant results lead to Granger-causality tests that in turn validate the hypothesis of a positive impact of speculation in futures markets to returns on the underlying commodities.  相似文献   
33.
This paper investigates time–frequency co-movements between crude oil prices and interest rates. To test this relationship, the study applied a continuous wavelet and cross wavelet approaches to data from West Texas Intermediate (WTI) crude oil prices and interest rates in the United States (U.S.). Results from the sample period revealed significant relationships, in the intermediate term, between WTI crude oil prices and U.S. interest rates. Moreover, co-movements between oil price and interest rate variables were especially sensitive during abnormal political events and periods of financial ‘meltdown’. We further use Partial Wavelet Coherence (PWC) and Multiple Wavelet Coherence (MWC) methods to investigate the impacts of five major control variables namely GDP growth, unemployment, three-month Treasury bill, CPI index and industrial production index. The results show a powerful impact of control variables on oil-interest rates co-movements under different frequencies. Finally, we show evidence of co-integrating long run relationship between oil markets and control variables. These results have important implications for energy investors and policy makers.  相似文献   
34.
With rapid increases in global food demand and production, oil palm expansion constitutes a major emerging challenge for forest conservation in Amazonia and other tropical forest regions. This threat is evident in the Peruvian Amazon, where local and national incentives for oil palm cultivation along with growing large-scale investments translate into accelerated oil palm expansion. Environmental sustainability of oil palm cultivation in the Peruvian Amazon is contingent on policy incentives for expansion onto already-cleared lands instead of biodiverse, high carbon primary rainforests. Previous research indicates that while industrial plantations use less land area than local smallholders, companies have a higher tendency to expand into primary rainforests. However, the motivations behind these differing expansion scenarios remain unclear. In this study we combine data from optical and radar satellite sensors with training information, field discussions, and review of public documents to examine the policy incentives and spatial patterns associated with oil palm expansion by smallholders and industries in one of Peru’s most rapidly changing Amazonian landscapes: the Ucayali region of the city of Pucallpa. Based on our satellite-based land cover change analysis, we found that between 2010 and 2016, smallholders utilized 21,070 ha more land area for oil palm than industries but industrial expansion occurred predominantly in old growth forests (70%) in contrast to degraded lands for smallholders (56%). Our analysis of national policies related to oil palm expansion reveal policy loopholes associated with Peru’s “best land use” classification system that allow for standing forests to undergo large-scale agricultural development with little government oversight. We conclude that both sectors will need careful, real-time monitoring and government engagement to reduce old-growth forest loss and develop successful strategies for mitigating future environmental impacts of oil palm expansion.  相似文献   
35.
We propose a novel test to measure market efficiency while estimating the time-varying risk premiums of commodity futures, given that the prices are heteroscedastic. The risk premium is estimated using a state-space model with a Kalman filter modified for heteroscedasticity. Using 79 commodity futures traded on 16 exchanges during the period 2000–2014 and a Monte Carlo simulation, we demonstrate that the proposal produces robust results compared with conventional approaches. The global financial crisis has improved the efficiency and affected the trading volumes of commodity futures, but it has had no effect on the average or the volatility of risk premiums.  相似文献   
36.
Educational policy is implicitly futures oriented, yet in most instances fails to engage learners with explicit futures tools and concepts at a school level. Futures studies in education, or futures education has the potential to reposition learning as purposeful and mobilizes the lives of participants by connecting the curriculum of schools with the multifaceted futures of learners. This is a complex task within the tensions often existing between: the cultural role of a school, the expectations of a society, the expertise of teachers, and the increasingly diverse needs of learners (Bateman, 2012). It is between the tensions of these things that the ‘ethical’ issues of what is taught, or omitted as content in a classroom and the consequences of these choices are evident.This paper highlights ethical and moral dilemmas, as they were apparent in two futures education projects. In the first study, the teachers discuss the inherent limitations of offering a broader and more futures oriented curriculum. In the second study, teachers reflect upon their students’ anxiety with regards to futures images as they are interrogated within a curriculum study. Each of these studies highlights the ethical challenges that arise, when possible, preferable and probable futures are developed as part of learning in school settings, which are culturally and demographically diverse.Tirri and Husu (2002) highlight the ethical dilemmas, which emerge in classrooms around the world, based on conflicts in values and competing intentions between key stakeholders. In the studies which contribute to this discussion, there is evidence to suggest that futures thinking causes conflict within an individual's perception of how the world should be, or their worldview as a result of futures imagining which goes beyond what is taken for granted, or is an assumed future eventuality. In the same way, Carrington, Deppeler, and Moss (2010) argue that all curriculum choices about what is taught (or not taught) in a classroom reflect an ethical decision made by a teacher, with regards to what is foregrounded for learning and what is omitted.It is crucial to re-examine the role of a school in educating students for their futures, as opposed to educating students with an aim of furthering governmental agendas. More significantly, however, as this paper highlights, it is exploring the boundaries of what is acceptable or unacceptable, appropriate or inappropriate to teach in a classroom, given the changing diversities of schools and education systems throughout the world.  相似文献   
37.
This paper has two aims. We first examine the dynamic spillovers between Bitcoin and 12 developed equities, gold, and crude oil for different market conditions using a Bayesian Time-Varying Parameter Vector Autoregressive (TVP-VAR) model with daily spot prices. Our econometric approach enables us to capture the left and right tails as well as the shoulders of the return distribution corresponding to volatility spillovers under the bear, normal, and bull market states among these financial assets. We quantify and trace the dependence and directional predictability from Bitcoin to other assets using the sample cross-quantilogram. Our key findings offer convincing evidence of time variation in the level of volatility. Spillovers between Bitcoin and other financial assets intensify during extreme global market conditions. Secondly, results from the cross-quantilogram indicate strong dependence and positive directional predictability between Bitcoin and most equities and crude oil when market returns are bullish. However, during the bearish market period, there is negative dependence and predictability from Bitcoin to stocks in Finland, the Netherlands, the U.S.A, and the crude oil market only. This implies that Bitcoin can act as a hedge to stocks in Finland, the Netherlands, the U.S.A, and the crude oil market. However, insignificant dependence and directional predictability from Bitcoin to the remaining assets indicate that Bitcoin may act as a safe-haven to these assets during bearish markets. Our findings hold important implications for both international investors and portfolio managers who consider Bitcoin as part of their portfolio diversification and other investment strategies.  相似文献   
38.
This study examines the effect of oil price dynamics on quarterly earnings and their predictability with a sample of 30 airlines for 1994–2017. First, we document a significantly positive impact of demand-driven oil shocks on airline earnings, suggesting that the revenue effect from shifting air travel demands dominates the cost effect of aviation fuels. Regarding earnings predictability, we find evidence of deterioration in oil-volatile quarters as indicated by both the earnings variability based on common benchmarks and the quality of analyst forecasts issued early in the quarter. We further show that supply-driven oil shocks have a more detrimental impact on earning predictability than demand-driven oil shocks. Finally, we do not find supporting evidence for the possible moderating effect of hedging.  相似文献   
39.
Substantial decline in oil prices observed since the second half of 2014 has brought forward discussions on the impact of oil prices on the external balance. This decline is expected to shift real income from oil exporter countries to oil importer countries. In this context, we study the effect of change in oil prices on Turkey’s exports taking into account the fact that Turkey’s export to oil exporting countries has approximately one-third share in total exports, while export to oil importing countries has a share of two-thirds. At the first step, we analyse the effect of oil prices on economic growth of trade partners of Turkey, where countries are grouped according to their net oil export position. We find that the effect of oil prices on different country groups’ growth is asymmetric. In the second stage, for two groups of countries, we estimate growth-export elasticity through Turkey’s export demand function. Finally, we calculate the net effect of oil prices on exports considering different income effects caused by oil price change on each country groups. Results indicate that the net effect of oil prices on the exports is limited given the current export shares.  相似文献   
40.
Both scenario development and design practices incorporate elements of storytelling, but this use remains undertheorised. This paper will draw upon literary theory, film theory and science fiction criticism to develop an analytical model of narrative structure and rhetorics which speaks to the concerns of scenario developers and designers when engaged in shaping the final outputs or deliverables of a futures project.After highlighting the differing role of telos in art and futures and defining the metacategory of “narratives of futurity”, this paper then defines the terms “story”, “narrative”, “narrator” and “world” in the literary context. It then shows how those concepts map onto futures practice, before going into detail regarding the variety of narrative strategies available across a range of different forms and media, and the qualitative effects that they can reproduce in audiences. There follows the construction of a 2 × 2 matrix based on the critical concepts of narrative mode and narrative logic, within which narratives of futurity might be usefully catalogued and compared, and from which certain broad conclusions may be reached as regards the relation between choice of medium and rhetorical effect. The implications of this analysis are explored in detail.  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