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   367883篇
  免费   15065篇
  国内免费   2028篇
财政金融   53384篇
工业经济   23127篇
计划管理   72553篇
经济学   81250篇
综合类   30034篇
运输经济   4584篇
旅游经济   5847篇
贸易经济   57525篇
农业经济   22597篇
经济概况   33572篇
信息产业经济   72篇
邮电经济   431篇
  2023年   3290篇
  2022年   6341篇
  2021年   10689篇
  2020年   9456篇
  2019年   8664篇
  2018年   8649篇
  2017年   11067篇
  2016年   9354篇
  2015年   9813篇
  2014年   14745篇
  2013年   31877篇
  2012年   26119篇
  2011年   27735篇
  2010年   25982篇
  2009年   24243篇
  2008年   23088篇
  2007年   21800篇
  2006年   20217篇
  2005年   16650篇
  2004年   8973篇
  2003年   7524篇
  2002年   6249篇
  2001年   5667篇
  2000年   4434篇
  1999年   3600篇
  1998年   2993篇
  1997年   2645篇
  1996年   2421篇
  1995年   2108篇
  1994年   1984篇
  1993年   1962篇
  1992年   1827篇
  1991年   1647篇
  1990年   1474篇
  1989年   1265篇
  1988年   1172篇
  1987年   1166篇
  1986年   1150篇
  1985年   1497篇
  1984年   1474篇
  1983年   1299篇
  1982年   1123篇
  1981年   1147篇
  1980年   1022篇
  1979年   973篇
  1978年   816篇
  1977年   759篇
  1976年   584篇
  1975年   556篇
  1974年   506篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
Improving access is a priority in the offshore wind sector, driven by the opportunity to increase revenues, reduce costs, and improve safety at operational wind farms. This paper describes a novel method for producing probabilistic forecasts of safety-critical access conditions during crew transfers. Methods of generating density forecasts of significant wave height and peak wave period are developed and evaluated. It is found that boosted semi-parametric models outperform those estimated via maximum likelihood, as well as a non-parametric approach. Scenario forecasts of sea-state variables are generated and used as inputs to a data-driven vessel motion model, based on telemetry recorded during 700 crew transfers. This enables the production of probabilistic access forecasts of vessel motion during crew transfer up to 5 days ahead. The above methodology is implemented on a case study at a wind farm off the east coast of the UK.  相似文献   
992.
Due to the serious increase of environmental pollution in China, environmental regulations have become significantly stringent. Such regulations are playing an increasingly important role in the development of small enterprises (SEs) in China, especially in SEs' market entry. However, existing studies pay little attention to this issue. This paper investigates for the first time the effect of environmental regulations on SEs' market entry and the mechanism of environmental regulation effects in China. We consider two sets of panel data for the periods 2003–2010 and 2012–2015 in China. We also use the fixed effect model and the instrumental variable method to explore the role of environmental regulations in SEs' market entry. The results show that, overall, environmental regulations play a significantly positive and robust role in SEs' market entry. However, the mechanisms associated with the effect of environmental regulations on different innovative types of SEs differ. Environmental regulations promote the market entry of SEs with product innovation, but this impact is not significant for SEs with research and development (R&D) activities and R&D institutions. Our findings indicate that China's SEs prefer product innovation, which is a lower level innovative type, over R&D innovation, as a means to avoid the negative impact of stringent environmental regulations.  相似文献   
993.
Recently, human activities are more and more invasive with respect to biodiversity. Several studies highlighted the key role played by accountants in contributing to the development of tools able to support company in assessing, reporting, and disseminating, as well as accomplishing, the preservation of natural species and ecosystems (King and Atkins, 2016). Corporate reporting of environmental information might increase the credibility of forest certifications, given that some scholars argued that certified forests are not often run, in a sustainable way. Moreover, certifications sometimes cover harmful forest practices (Elad, 2014) and do not ensure a good quality of environmental reporting and performance. The research question therefore intends to explore how extinction accounting and accountability (EAA) is able to reflect ex post the company's business strategy and, at the same time, influence ex ante its formulation by easing the prevention of deforestation risk and addressing the issue of credibility through specific actions. In more detail, the “Emancipatory Framework for Extinction Accounting and Accountability” (EFEAA) (Atkins and Maroun, 2018) was tested using content and interpretative analyses based on the reports inherent to top four companies working in West Europe in the tissue industry, where the preservation of forest heritage is a “compulsory route” for assuring the business sustainability, in terms of both raw material renewal and brand reputation. The findings highlighted the first attempt to carry out a qualitative research over the management of forest issues. In our study, companies tend to report advantages arising from the use of forest, but this kind of disclosure is too generic without providing evidence over the ecosystem services forests produce. Moreover, firm size affects the quantity and the quality of disclosure. At last, managerial implications and future research avenues are outlined and discussed.  相似文献   
994.
A new class of forecasting models is proposed that extends the realized GARCH class of models through the inclusion of option prices to forecast the variance of asset returns. The VIX is used to approximate option prices, resulting in a set of cross-equation restrictions on the model’s parameters. The full model is characterized by a nonlinear system of three equations containing asset returns, the realized variance, and the VIX, with estimation of the parameters based on maximum likelihood methods. The forecasting properties of the new class of forecasting models, as well as a number of special cases, are investigated and applied to forecasting the daily S&P500 index realized variance using intra-day and daily data from September 2001 to November 2017. The forecasting results provide strong support for including the realized variance and the VIX to improve variance forecasts, with linear conditional variance models performing well for short-term one-day-ahead forecasts, whereas log-linear conditional variance models tend to perform better for intermediate five-day-ahead forecasts.  相似文献   
995.
This paper takes the locally collected price quotes used to construct the CPI index in the UK for the period 1996–2013 and explores the impact of the Great Recession (2008‐9) on the pricing behaviour of firms. We develop a time series framework which captures the link between macroeconomic variables and the behaviour of prices in terms of the frequency of price change, the dispersion of price levels and the size, dispersion and kurtosis of price‐growth. We find strong evidence for inflation having an effect, but not output. The change in the behaviour of prices during the Great Recession is largely explained by the changes in inflation and VAT. Nevertheless, the magnitude of the inflation effect is sufficiently small that it need not influence monetary policy.  相似文献   
996.
In this article, we compare two kinds of environmental regulations—emissions taxes and green R&D subsidies—in private and mixed-duopoly markets in the presence of R&D spillovers. We show that a green R&D subsidy is better (worse) than an emissions tax when the green R&D is efficient (inefficient), irrespective of R&D spillovers, whereas the existence of a publicly owned firm encourages the government to adopt a subsidy policy. We also show that the optimal policy choice depends on R&D efficiency and spillovers. In particular, when green R&D is inefficient and the spillover rate is low (high), the government should choose an emissions tax and (not) privatize the state-owned firm. When green R&D is efficient, however, an R&D subsidy is better, but a privatization policy is not desirable for society, irrespective of spillovers.  相似文献   
997.
In this study we examine how the regulation of director attendance disciplines directors’ behavior, and consider the governance effect of such regulations. This examination exploits the differences between the requirements for director attendance at board meetings enacted by the Shanghai Stock Exchange (SHSE) and by the Shenzhen Stock Exchange (SZSE). Using a difference-in-differences model with a sample of A-share listed firms from 2006 to 2017, we document that the rate of meeting attendance by independent directors who serve with firms listed on the SHSE (SHIDs) has increased significantly since the exchange’s enforcement of the regulation on attendance. This positive effect has been more pronounced for independent directors with legal backgrounds. Further investigations find that the regulation of attendance plays a corporate governance role through the mechanism of enhanced monitoring. The attendance regulation increases the SHIDs likelihood of casting dissenting votes, and it leads to both better accounting performance and higher firm value. In addition, SHIDs are more likely to depart from firms listed on the SHSE, and to transfer their directorships to firms listed on the SZSE, which has a less constraining attendance requirement. Our findings provide evidence of how external regulation shapes director attendance and voting behavior in emerging markets.  相似文献   
998.
Dark pools are financial trading venues where orders are entered and matched in secret so that no order information is leaked. By preventing information leakage, dark pools offer the opportunity for large volume block traders to avoid the costly effects of market impact. However, dark pool operators have been known to abuse their privileged access to order information. To address this issue, we introduce a provably secure multi-party computation mechanism that prevents an operator from accessing and misusing order information. Specifically, we implement a secure emulation of Turquoise Plato Uncross, Europe's largest dark pool trading mechanism, and demonstrate that it can handle real world trading throughput, with guaranteed information integrity.  相似文献   
999.
ABSTRACT

This paper examines how credit default swaps (CDS) affect the corporate investment of the referenced entities. We document a significant reduction in corporate investment after CDS trading, a result that is robust to alternative model specifications and a set of endogeneity tests. Our findings of the increased firm risk and cost of capital support the costly external capital channel. The cross-sectional variations in CDS effects demonstrate that both reduced monitoring and the empty creditor problem might be the underlying forces driving the costly external capital channel. Our additional analysis implies that CDS trading is associated with an enhancement in investment efficiency for firms that are prone to overinvestment.  相似文献   
1000.
针对造价人才的执业环境的改变,分析行业在新形势下对咨询业务的新需求,并根据业务实践总结出BIM、PPP、全过程工程咨询等技术和管理模式的出现对造价人才的需求,在此基础上构建新形势下工程造价人才的能力指标体系,并提出了与能力标准体系呼应的核心课程体系设置思路。  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