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   9738篇
  免费   229篇
财政金融   1847篇
工业经济   827篇
计划管理   1714篇
经济学   2153篇
综合类   119篇
运输经济   70篇
旅游经济   153篇
贸易经济   1506篇
农业经济   482篇
经济概况   1074篇
信息产业经济   1篇
邮电经济   21篇
  2023年   59篇
  2021年   73篇
  2020年   127篇
  2019年   193篇
  2018年   203篇
  2017年   226篇
  2016年   237篇
  2015年   138篇
  2014年   213篇
  2013年   964篇
  2012年   304篇
  2011年   341篇
  2010年   293篇
  2009年   329篇
  2008年   289篇
  2007年   260篇
  2006年   241篇
  2005年   201篇
  2004年   190篇
  2003年   191篇
  2002年   222篇
  2001年   197篇
  2000年   227篇
  1999年   197篇
  1998年   205篇
  1997年   193篇
  1996年   202篇
  1995年   159篇
  1994年   150篇
  1993年   169篇
  1992年   172篇
  1991年   173篇
  1990年   167篇
  1989年   121篇
  1988年   109篇
  1987年   113篇
  1986年   126篇
  1985年   184篇
  1984年   142篇
  1983年   131篇
  1982年   108篇
  1981年   131篇
  1980年   112篇
  1979年   118篇
  1978年   119篇
  1977年   67篇
  1976年   83篇
  1975年   65篇
  1973年   66篇
  1972年   58篇
排序方式: 共有9967条查询结果,搜索用时 18 毫秒
991.
In this paper, we develop modeling tools to forecast Value-at-Risk and volatility with investment horizons of less than one day. We quantify the market risk based on the study at a 30-min time horizon using modified GARCH models. The evaluation of intraday market risk can be useful to market participants (day traders and market makers) involved in frequent trading. As expected, the volatility features a significant intraday seasonality, which motivates us to include the intraday seasonal indexes in the GARCH models. We also incorporate realized variance (RV) and time-varying degrees of freedom in the GARCH models to capture more intraday information on the volatile market. The intrinsic tail risk index is introduced to assist with understanding the inherent risk level in each trading time interval. The proposed models are evaluated based on their forecasting performance of one-period-ahead volatility and Intraday Value-at-Risk (IVaR) with application to the 30 constituent stocks. We find that models with seasonal indexes generally outperform those without; RV can improve the out-of-sample forecasts of IVaR; student GARCH models with time-varying degrees of freedom perform best at 0.5 and 1 % IVaR, while normal GARCH models excel for 2.5 and 5 % IVaR. The results show that RV and seasonal indexes are useful to forecasting intraday volatility and Intraday VaR.  相似文献   
992.
The Mississippi Bubble, South Sea Bubble and the Dutch Windhandel of 1720 together represent the world's first global financial bubble. We hand-collect cross-sectional price data and investor account data from 1720 to test theories about market bubbles. Our tests suggest that innovation was a key driver of bubble expectations. We present evidence against the currently prevailing debt-for-equity conversion hypothesis and relate stock returns to innovations in Atlantic trade and insurance. We find evidence consistent with the innovation-driven bubble dynamics documented by Pastor and Veronesi (2009) for new economy stocks. Our evidence seems inconsistent with clientele-based theories that emphasize bubble-riding and short-sales restrictions.  相似文献   
993.
994.
In this paper we present a framework for analyzing changes in strategic performance. Traditional measures for comparing the strategic performance across firms or over time have been return on investment (ROI) and its component ratio, return on sales (ROS). We decompose the ROS ratio into four separate ratios that capture the impact of changes in a firm's productivity, price recovery, product mix and capacity utilization on its profitability. These ratios help to highlight the micro sources of strategic success or failure. They can be used to assess changes in the performance of a firm compared to itself over time, or to other firms in its industry group. This framework can also be used to evaluate changes in the dynamic performance of an industry as a whole. We illustrate the use of these ratios with a 4-year analysis of the performance of a large manufacturing company. We also demonstrate how the technique can be applied to an industry with an evaluation of the performance of U.S. telecommunications firms between 1975 and 1987, a period during which the industry experienced a progressive increase in competitive pressure.  相似文献   
995.
S. K. Bar-Lev  D. Plachky 《Metrika》1989,36(1):331-336
Summary Completeness of a family of probability distributions implies its bounded completeness but not conversely. An example of a family which is boundedly complete but not complete was presented by Lehmann and Scheffe [5]. This appears to be the only such example quoted in the statistical literature. The purpose of this note is to provide further examples of this type. It is shown that any given family of power series distributions can be used to construct a class containing infinitely many boundedly complete, but not complete, families. Furthermore, it is shown that the family of continuous distributions , is boundedly complete, but not complete, whereU denotes the uniform distribution on [a, b] and {P ϑ,ϑ ∈ IR}, is a translation family generated by a distributionP 0 with mean value zero, which is continuous with respect to the Lebesgue measure.  相似文献   
996.
In this paper we present a model which unifies several existing models with respect to two phases of the planning process of a Flexible Manufacturing System. These phases are the system setup phase and the scheduling phase and in literature they usually are considered separately. We give a mathematical formulation encompassing both phases. From this formulation several existing approaches can be deduced. We also describe some heuristic methods for our model and present the computational results.  相似文献   
997.
This article explores the historical background of affirmative action in the United States, and reviews haw federal support for it has changed since the Civil War. Several recent US Supreme Court cases deciding affirmative action issues are discussed, with speculation about the future of affirmative action in light of these decisions. The article also discusses the implications of these rulings for human resource practitioners.  相似文献   
998.
In this paper consistent and, in a well–defined sense, optimal moment–estimators of the regression coefficient in a simple regression model with errors in variables are derived. The asymptotic variance and other asymptotic properties of these estimators are given. As is known for a long time, serious estimation problems exist in this model. There are two ways out of this problem: using either additional assumptions or additional information in the data. A lot of attention has been paid to the use of additional assumptions. However, quite often this leads to rather unrealistic models. In this paper we use additional information in the data. That means here that, besides first and second order moments, third order moments are formulated as functions of the model parameters. Besides theoretical derivations a small study with generated data is discussed. This study shows that for samples larger than 50 the estimates we consider behave nicely.  相似文献   
999.
This paper investigates the residential development process using a dynamic model of an open city. The model is used to analyze how the density and timing of development at various sites respond to changes in exogenous trajectories and functions. In particular, the impact of income and equilibrium utility trajectory variations as well as transportation and construction cost changes are evaluated for the general model with no specific functional forms assumed. Sufficient conditions for predicted responses are derived and interpreted.  相似文献   
1000.
A. K. Gupta  C. F. Wong 《Metrika》1984,31(1):327-332
Summary In this paper a Morgenstern-type bivariate gamma distribution has been studied. Its moment generating function has been derived. The distribution of the product and quotient are derived in terms of the modified Bessel function. The results for the independent case follow as special cases. Further the regression function has been analysed, in terms of its deviation from linear regression function.This research was initiated while the first author was a U.N. Consultant under the Statistical Training Program for Africa, visiting the University of Ghana.  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