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   35802篇
  免费   732篇
  国内免费   5篇
财政金融   5134篇
工业经济   1971篇
计划管理   4197篇
经济学   6316篇
综合类   656篇
运输经济   177篇
旅游经济   432篇
贸易经济   4776篇
农业经济   1253篇
经济概况   3992篇
水利工程   7552篇
信息产业经济   3篇
邮电经济   80篇
  2021年   235篇
  2020年   313篇
  2019年   479篇
  2018年   1388篇
  2017年   1334篇
  2016年   1082篇
  2015年   411篇
  2014年   703篇
  2013年   2787篇
  2012年   1184篇
  2011年   1696篇
  2010年   1329篇
  2009年   1329篇
  2008年   1400篇
  2007年   1574篇
  2006年   856篇
  2005年   902篇
  2004年   927篇
  2003年   712篇
  2002年   657篇
  2001年   553篇
  2000年   542篇
  1999年   538篇
  1998年   475篇
  1997年   513篇
  1996年   503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   370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 62 毫秒
1.
Water Resources Management - The water evaluation and planning (WEAP) approach and the invasive weed optimization algorithm (IWOA) are herein employed to determine the optimal operating policies in...  相似文献   
2.
Portuguese Economic Journal - A set of RLS-type models with ARMA and ARFIMA dynamics is estimated and compared in a forecasting exercise with ARFIMA, GARCH and FIGARCH models. It is an extension of...  相似文献   
3.
This paper presents an approach to assessing the efficacy of public spending on research and development in state programs. At present, there is a need to develop a unified approach to the analysis and evaluation of the efficacy of such spending from the perspective of participants in state programs (federal executive bodies). The proposed approach does not allow evaluating the efficacy of public spending on the development of research areas assigned to the authors.  相似文献   
4.
5.
Growing urbanisation in South Africa is reflected in burgeoning Working class and informal township settlements on the fringes of its major towns and cities. Paired with this is an increasing reliance on cash as the primary means of economic transaction, which has in turn stimulated the growth of micro-enterprise business activities within the township context. This article discusses the findings of an eight-township small-area census which occurred between 2010 and 2013 in Cape Town, Johannesburg, Ekurhuleni and Durban townships representing 250 000 residents. The researchers were able to establish the scope and scale of informal food and drink retailing in these localities. Of the 10 049 micro-enterprises located in the study, some 3966 (or 39% of the total) trade in food. These include enterprises in primary production, fresh produce retailing, grocery retailing from house and spaza shops, and informal foodservice enterprises. Food is the basis for much township informal business and plays an important role in making food increasingly affordable and locally accessible, and in creating cash employment. The article builds on the knowledge base of the township informal economy role in bolstering food security needs for the marginalised.  相似文献   
6.
Without guaranteed compensation, granted by the German Renewable Energy Sources Act (Erneuerbare Energien Gesetz/EEG), biogas plants compete with all other plant types on the market for electrical energy. However, exchange-based electricity products do not currently permit an economically viable operation of biogas plants owing to their cost situation.  相似文献   
7.
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st  相似文献   
8.
9.
Power Technology and Engineering - The work done on the test site to ensure the operational safety of the powerhouse of the Zagorsk PSP-2 after its leveling is described. The controlled...  相似文献   
10.
During patent litigation, pay‐for‐delay (P4D) deals involve a payment from a patent holder of a branded drug to a generic drug manufacturer to delay entry and withdraw the patent challenge. In return for staying out of the market, the generic firm receives a payment, and/or an authorized licensed entry at a later date, but before the patent expiration. We examine why such deals are stable when there are multiple potential entrants. We combine the first‐mover advantage for the first generic with the ability of the branded manufacturer to launch an authorized generic (AG) to show when P4D deals are an equilibrium outcome. We further show that limiting a branded firm's ability to launch an AG before entry by a successful challenger will deter such deals. However, removing exclusivity period for the first generic challenger will not.  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