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   19716篇
  免费   580篇
  国内免费   13篇
财政金融   3504篇
工业经济   1551篇
计划管理   3412篇
经济学   4281篇
综合类   342篇
运输经济   175篇
旅游经济   392篇
贸易经济   3535篇
农业经济   972篇
经济概况   2094篇
邮电经济   51篇
  2021年   125篇
  2020年   227篇
  2019年   321篇
  2018年   416篇
  2017年   460篇
  2016年   444篇
  2015年   311篇
  2014年   478篇
  2013年   1976篇
  2012年   589篇
  2011年   617篇
  2010年   597篇
  2009年   656篇
  2008年   656篇
  2007年   620篇
  2006年   538篇
  2005年   519篇
  2004年   468篇
  2003年   481篇
  2002年   430篇
  2001年   425篇
  2000年   419篇
  1999年   384篇
  1998年   380篇
  1997年   388篇
  1996年   387篇
  1995年   329篇
  1994年   332篇
  1993年   351篇
  1992年   325篇
  1991年   306篇
  1990年   284篇
  1989年   252篇
  1988年   210篇
  1987年   226篇
  1986年   237篇
  1985年   349篇
  1984年   361篇
  1983年   332篇
  1982年   302篇
  1981年   293篇
  1980年   271篇
  1979年   270篇
  1978年   198篇
  1977年   195篇
  1976年   173篇
  1975年   136篇
  1974年   126篇
  1973年   125篇
  1972年   88篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
11.
An axiomatic approach is applied to the problem of extracting a ranking of the alternatives from a pairwise comparison ratio matrix. The ordering induced by row geometric mean method is proved to be uniquely determined by three independent axioms, anonymity (independence of the labelling of alternatives), responsiveness (a kind of monotonicity property) and aggregation invariance, which requires the preservation of group consensus, that is, the pairwise ranking between two alternatives should remain unchanged if unanimous individual preferences are combined by geometric mean.  相似文献   
12.
The general consensus in the volatility forecasting literature is that high-frequency volatility models outperform low-frequency volatility models. However, such a conclusion is reached when low-frequency volatility models are estimated from daily returns. Instead, we study this question considering daily, low-frequency volatility estimators based on open, high, low, and close daily prices. Our data sample consists of 18 stock market indices. We find that high-frequency volatility models tend to outperform low-frequency volatility models only for short-term forecasts. As the forecast horizon increases (up to one month), the difference in forecast accuracy becomes statistically indistinguishable for most market indices. To evaluate the practical implications of our results, we study a simple asset allocation problem. The results reveal that asset allocation based on high-frequency volatility model forecasts does not outperform asset allocation based on low-frequency volatility model forecasts.  相似文献   
13.
Our purpose is to explore the concept of “sustainability” when understood from a performative perspective, i.e. as a concept that is filled with meaning across time. Drawing on a 10 year-long study of the digital footprint of Stockholm Royal Seaport, claimed to be northern Europe's largest sustainable urban development district, we show that “sustainability” emerged as the project became associated with particular places, projects, histories, and technologies. This means that “sustainability” was local in that it was situated in the particular spatial context of the project; temporal in that it was situated in a particular time; and political in that it expressed particular values and perspectives. The study contributes to explaining why “sustainability” remains—and always will remain—a contested concept, which is why sustainability transitions are complex. Consequently, we suggest that the transition towards sustainability always involves the transition of sustainability, something that needs to be acknowledged in order for a transition to actually become sustainable.  相似文献   
14.
Both soft, noncontractible, and hard, contractible, information are informative about managerial ability and future firm performance. If a manager's future compensation depends on expectations of ability or future performance, then the manager has implicit incentives to affect the information. We examine the real incentive effects of soft information in a dynamic agency with limited commitment. When long-term contracts are renegotiated, the rewards for future performance inherent in long-term contracts allow the principal partial control over the implicit incentives. This is because the soft information affects the basis for contract renegotiation. With short-term contracts, the principal has no control over the basis for contract negotiation, and thus long-term contracts generally dominate short-term contracts. With long-term contracts, the principal's control over implicit incentives is characterized in terms of effective contracting on an implicit aggregation of the soft information that arises from predicting (forming expectations of) future performance. We provide sufficient conditions for soft information to have no real incentive effects. In general, implicit incentives not controllable by the principal include fixed effects, such as career concerns driven by labor markets external to the agency. When controllable incentives span the fixed effects of career concerns, the latter have no real effects with regard to total managerial incentives—they would optimally be the same with or without career concerns. Our analysis suggests empirical tests for estimating career concerns that should explicitly incorporate noncontractible information.  相似文献   
15.
吕波  王辉  何悦  周仲鸿 《科技和产业》2021,21(10):252-259
探究黑龙江旅游网络关注度时空演变特征对黑龙江旅游业良性发展具有重要意义.利用百度指数获取2011—2018年全国和分地区黑龙江旅游网络关注度逐日搜索指数数据.从时间分布、空间分布、时空集聚3个方面研究其演变特征.研究表明:2011—2018年全国黑龙江旅游网络关注度年际变化总体呈现上升趋势,月际变化呈"W"形;2011—2018年31个省区市黑龙江旅游网络关注度空间差异较大、季节性影响显著;东部地区黑龙江旅游网络关注度偏高,西部地区黑龙江旅游网络关注度的季节差异最明显;东部地区内的黑龙江旅游网络关注度差异性最小,西部地区内差异性最大;黑龙江旅游网络关注度具有正空间自相关,部分东部、中部地区表现为高高集聚,多数西部地区表现为低低集聚.  相似文献   
16.
Motor carrier safety is an important concern of shippers, carriers, policy makers, consignees, insurance providers, and the motoring public. One aspect of carrier safety that has garnered substantial attention is whether carriers making greater use of owner–operators are more or less safe vis‐à‐vis carriers making greater use of employee drivers. Currently, conflicting theoretical predictions exist regarding the direction of this relationship. In this article, we offer a reconciliation of the alternative theoretical predictions by developing a coherent theory that merges sociological rational choice theory and theory regarding motor carrier safety. We subject our theory to empirical testing by fitting a series of seemingly unrelated regression models to a vector of safety measures tracked as part of the Federal Motor Carrier Safety Administration's Compliance, Safety, and Accountability program. Our results are consistent with our proposed theory of owner—operator safety and provide meaningful theoretical and managerial implications and directions for future research.  相似文献   
17.
We investigate whether firms restructure board composition to align with changes in their contracting environment. Board size and independence increase with firm complexity, consistent with theoretical predictions. However, the hypothesized negative relation between board independence and information costs is evident only for firms completing acquisitions. Furthermore, board independence increases to offset increases in CEO power in a sample of firms making acquisitions, but decreases when CEO power increases in a large cross‐section of firms. We conclude that after the Sarbanes–Oxley Act of 2002, firms face constraints adjusting to target board structure, but these constraints can be mitigated by a shock to the contracting environment via acquisition.  相似文献   
18.
Internally‐promoted CEOs should have a deep understanding of their firm's products, supply chain, operations, business climate, corporate culture, and how to navigate among employees to get the information they need. Thus, we argue that internally‐promoted CEOs are likely to produce higher quality disclosure than outsider CEOs. Using a sample of US firms from the S&P1500 index from 2001 to 2011, we hand‐collect whether a CEO is hired from inside the firm and, if so, the number of years they worked at the firm before becoming CEO. We then examine whether managers with more internal experience issue higher quality disclosures and offer three main findings. First, CEOs with more internal experience are more likely to issue voluntary earnings forecasts than those managers with less internal experience as well as those managers hired from outside the firm. Second, CEOs with more internal experience issue more accurate earnings forecasts than those managers with less internal experience as well as those managers hired from outside the firm. Finally, investors react more strongly to forecasts issued by insider CEOs than to those issued by outsider CEOs. In additional analysis, we find no evidence that these results extend to mandatory reporting quality (i.e., accruals quality, restatements, or internal control weaknesses), perhaps because mandatory disclosure is subjected to heavy oversight by the board of directors, auditors, and regulators. Overall, our findings suggest that when managers have work experience with the firm prior to becoming the CEO, the firm's voluntary disclosure is of higher quality.  相似文献   
19.
This paper uses a reduced‐form approach to derive a closed‐form pricing formula for defaultable bonds. The authors specify the default hazard rate as an affine function of multiple variables which follow the Lévy jump‐diffusion processes. Because such specification allows greater flexibility in the generation of a valid probability of default, their pricing model should be more accurate than the valuation models in traditional studies, which ignore the jump effects. This paper also proposes a new method for estimating the parameters in a Lévy Jump‐diffusion process. The real data from the Taiwanese bond market are used to illustrate how their model can be applied in practical situations. The authors compare the pricing results for the influential variables with no jump effects, with jump magnitudes following the normal distribution, and with jump magnitudes following the gamma distribution. The results reveal that the predictive ability is the best for the model with the jump components. The valuation model shown in this paper should help portfolio managers more accurately price defaultable bonds and more effectively hedge their portfolio holdings.  相似文献   
20.
Public pension burdens in most emerging Asian economies are still relatively small. However, there are a number of reasons to believe that they will increase markedly in the coming years. First, many Asian economies will face rapidly ageing populations, which will raise pension and other old‐age‐related spending dramatically. Second, as economies develop, political pressures to expand the coverage of public pensions and raise pension benefits will likely increase. The first objective of this paper is to identify the potential fiscal burden of public pensions in 23 emerging Asian economies, based on econometric models and forecasts of GDP and demographic trends. Using two different methodologies yields estimated increases in the average share of public pension expenditures in GDP of 1.0 percentage point and 3.6 percentage points by 2030 compared with current levels. We believe the latter estimate is more realistic. The second objective is to recommend policies to provide adequate funding for public pension needs, including enhancing the efficiency of social insurance programs, improving the balance of revenues and expenditures, implementing more explicit fiscal rules and frameworks, and establishing stronger fiscal surveillance at the national and regional levels.  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