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   29819篇
  免费   698篇
  国内免费   7篇
财政金融   4183篇
工业经济   1529篇
计划管理   3484篇
经济学   4862篇
综合类   474篇
运输经济   115篇
旅游经济   249篇
贸易经济   4030篇
农业经济   786篇
经济概况   2937篇
水利工程   7834篇
信息产业经济   4篇
邮电经济   37篇
  2021年   205篇
  2020年   293篇
  2019年   360篇
  2018年   1352篇
  2017年   1307篇
  2016年   995篇
  2015年   383篇
  2014年   594篇
  2013年   2231篇
  2012年   950篇
  2011年   1519篇
  2010年   1235篇
  2009年   1152篇
  2008年   1209篇
  2007年   1450篇
  2006年   774篇
  2005年   757篇
  2004年   815篇
  2003年   610篇
  2002年   498篇
  2001年   433篇
  2000年   448篇
  1999年   441篇
  1998年   451篇
  1997年   386篇
  1996年   374篇
  1995年   367篇
  1994年   369篇
  1993年   363篇
  1992年   414篇
  1991年   394篇
  1990年   347篇
  1989年   313篇
  1988年   291篇
  1987年   296篇
  1986年   293篇
  1985年   371篇
  1984年   378篇
  1983年   362篇
  1982年   338篇
  1981年   335篇
  1980年   310篇
  1979年   310篇
  1978年   315篇
  1977年   291篇
  1976年   288篇
  1975年   278篇
  1974年   239篇
  1973年   228篇
  1972年   191篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
1.
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   
2.
3.
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   
4.
5.
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   
6.
Review of Quantitative Finance and Accounting - We examine how changes in dividend policy in 2008 as the financial crisis was unfolding influenced firm risk-adjusted returns in the following years....  相似文献   
7.
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   
8.
Most development projects encounter a highly uncertain entitlement process that is largely uncontrollable by developers. In this study, entitlement is modeled as a separate stage within a compound real option, where developers begin with minimal control (maximum risk) and each successful stage increases control (decreases risk). We solve the model analytically, provide three‐dimensional numerical comparisons, and empirically test the model's predictions using hand collected rezoning petitions. Our main result refines the classic development option model: developers first invest early (secure entitlements) in order to obtain the option to subsequently delay investment (construct the optimal building at the optimal time).  相似文献   
9.
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   
10.
This study back-tests a marginal cost of production model proposed to value the digital currency Bitcoin. Results from both conventional regression and vector autoregression (VAR) models show that the marginal cost of production plays an important role in explaining Bitcoin prices, challenging recent allegations that Bitcoins are essentially worthless. Even with markets pricing Bitcoin in the thousands of dollars each, the valuation model seems robust. The data show that a price bubble that began in the Fall of 2017 resolved itself in early 2018, converging with the marginal cost model. This suggests that while bubbles may appear in the Bitcoin market, prices will tend to this bound and not collapse to zero.  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