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   30721篇
  免费   732篇
  国内免费   5篇
财政金融   4588篇
工业经济   1709篇
计划管理   3562篇
经济学   5292篇
综合类   380篇
运输经济   175篇
旅游经济   432篇
贸易经济   3646篇
农业经济   1253篇
经济概况   3429篇
水利工程   6935篇
信息产业经济   1篇
邮电经济   56篇
  2021年   235篇
  2020年   316篇
  2019年   482篇
  2018年   708篇
  2017年   682篇
  2016年   715篇
  2015年   404篇
  2014年   675篇
  2013年   2772篇
  2012年   1034篇
  2011年   1084篇
  2010年   791篇
  2009年   871篇
  2008年   937篇
  2007年   962篇
  2006年   851篇
  2005年   780篇
  2004年   790篇
  2003年   550篇
  2002年   602篇
  2001年   546篇
  2000年   532篇
  1999年   539篇
  1998年   474篇
  1997年   513篇
  1996年   497篇
  1995年   452篇
  1994年   448篇
  1993年   477篇
  1992年   489篇
  1991年   480篇
  1990年   416篇
  1989年   401篇
  1988年   385篇
  1987年   375篇
  1986年   367篇
  1985年   541篇
  1984年   507篇
  1983年   481篇
  1982年   440篇
  1981年   410篇
  1980年   475篇
  1979年   419篇
  1978年   350篇
  1977年   343篇
  1976年   316篇
  1975年   340篇
  1974年   281篇
  1973年   299篇
  1972年   212篇
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
101.
An issue in the pricing of contingent claims is whether to account for consumption risk. This is relevant for contingent claims on stock indices, such as the FTSE 100 share price index, as investor’s desire for smooth consumption is often used to explain risk premiums on stock market portfolios, but is not used to explain risk premiums on contingent claims themselves. This paper addresses this fundamental question by allowing for consumption in an economy to be correlated with returns. Daily data on the FTSE 100 share price index are used to compare three option pricing models: the Black–Scholes option pricing model, a GARCH (1, 1) model priced under a risk-neutral framework, and a GARCH (1, 1) model priced under systematic consumption risk. The findings are that accounting for systematic consumption risk only provides improved accuracy for in-the-money call options. When the correlation between consumption and returns increases, the model that accounts for consumption risk will produce lower call option prices than observed prices for in-the-money call options. These results combined imply that the potential consumption-related premium in the market for contingent claims is constant in the case of FTSE 100 index options.  相似文献   
102.
Guatavita Lake is a small, sheltered tropical high mountain lake located in the Colombian Andes, with a closed watershed and a maximum depth of 25 m. It is the freshwater source for human consumption in nearby small towns, as well as being a site of cultural value for the country, as it was a sacred place to indigenous peoples until about five centuries ago. As the structure and function of this aquatic ecosystem is poorly understood, this study provides initial knowledge on its phytoplankton biomass dynamics, which should be useful in designing efficient management plans with environmental baseline information for similar lakes elsewhere. Physical and chemical data, and photosynthetic pigment concentrations, were measured for the period November 1999–November 2000 at the central vertical axis of Guatavita Lake. The vertical profile of the chlorophyll‐a concentration was closely related to the dissolved inorganic nitrogen concentrations and the thermal stratification characteristics. The maximum chlorophyll‐a concentration in the metalimnion was recorded for the thermal stratification period (November 1999–June 2000). Deepening of the maximum chlorophyll‐a concentration began in February, continuing to June, when it reached its lowest value at the 15 m depth. The phytoplankton biomass values showed an increment within the entire water column at the beginning of the mixing period (July). The relation between the metalimnetic peak of chlorophyll‐a and the dissolved inorganic nitrogen concentration suggests the growth of the phytoplankton community is limited mainly by the availability of nitrogen.  相似文献   
103.
The purpose of this essay is to examine psychoanalytically Argyris and Schon's contributions to organization theory and intervention. The author focuses his attention on the problem of individual and organizational resistance to change in the light of Argyris and Schon's cognitive psychological assumptions about learning, reasoning, and effectiveness.  相似文献   
104.
105.
There is a growing interest in the possibilities offered by combinations of waste stabilisation ponds (WSP) and constructed wetlands (CW). The purpose of our study was to compare treatment performances and nutrient cycling in a surface-flow wetland (SFW) and in a WSP treating secondary effluent. In the period between 2000 and 2003, a pilot SFW and a pilot WSP were constructed at the outlet of the wastewater treatment plant and their performance monitored while both were active under the same conditions. The SFW was planted with Phragmites australis and Eichhornia crassipes, while in the WSP development of algae was spontaneous. Performance efficiency was monitored by means of evaluation of physical and chemical parameters in water, by measurement of plant productivity and by analysis of N and P contents in biomass. The SFW with macrophytes proved more efficient in decreasing the suspended solids (64.6%), settleable solids (91.8%), organic N (59.3%), total N (38%), COD (67.2%) and BOD5 (72.1%) than the WSP. The WSP with algae was more efficient in treatment of ammonia nitrogen (48.9%) and ortho-phosphate (43.9%). The results of this study provide data that are of help in optimising combinations of SFW and WSP.  相似文献   
106.
107.
108.
109.
110.
This paper explores the explanatory power of Jensen's free cash flow hypothesis in managers' choice of LIFO versus FIFO. The association between FCF, and choice of inventory methods is based on the assumption that there is a potential conflict of interest between managers and shareholders when LIFO is the tax minimization method and that non-value-maximizing managers of firms with the FCF problem have incentives to choose FIFO, an income increasing method, in order to increase their compensation. However, since debt can act as a monitoring device and mitigate the agency problems of FCF, managers of firms with high FCF and high debt are less likely to choose FIFO than managers of firms with high FCF and low debt. The evidence is consistent with this expectation.  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