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   163718篇
  免费   4857篇
  国内免费   210篇
财政金融   26871篇
工业经济   12135篇
计划管理   23723篇
经济学   31427篇
综合类   2490篇
运输经济   1057篇
旅游经济   2564篇
贸易经济   24828篇
农业经济   6647篇
经济概况   18660篇
水利工程   18110篇
信息产业经济   11篇
邮电经济   262篇
  2021年   1475篇
  2020年   2151篇
  2019年   2855篇
  2018年   2977篇
  2017年   3154篇
  2016年   3373篇
  2015年   2767篇
  2014年   4243篇
  2013年   17024篇
  2012年   5714篇
  2011年   5856篇
  2010年   5088篇
  2009年   5475篇
  2008年   5239篇
  2007年   4655篇
  2006年   4940篇
  2005年   4723篇
  2004年   3838篇
  2003年   3329篇
  2002年   3297篇
  2001年   3175篇
  2000年   2923篇
  1999年   2830篇
  1998年   2617篇
  1997年   2693篇
  1996年   2546篇
  1995年   2324篇
  1994年   2299篇
  1993年   2260篇
  1992年   2339篇
  1991年   2221篇
  1990年   2073篇
  1989年   1922篇
  1988年   1821篇
  1987年   1842篇
  1986年   1848篇
  1985年   2644篇
  1984年   2549篇
  1983年   2339篇
  1982年   2209篇
  1981年   2144篇
  1980年   2159篇
  1979年   2076篇
  1978年   1882篇
  1977年   1823篇
  1976年   1644篇
  1975年   1483篇
  1974年   1399篇
  1973年   1403篇
  1972年   1102篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
燕麦为西藏自治区典型牧草之一,由于种植区地域辽阔,灌溉试验结果受限,西藏燕麦主要种植区的灌溉定额尚不明确。本文在西藏燕麦主要种植区内选取28个典型站点进行资料收集,遵循农业气候相似原则进行区域划分,基于水量平衡法揭示了西藏燕麦主要种植区灌溉定额的空间分布特征,并根据统计学原理分析了其影响因素。研究表明:燕麦主要种植区的灌溉定额呈由西藏中部至东部呈现先递增后递减的趋势,50%水文年下的燕麦灌溉定额在56~265 mm之间变化。降雨量是影响研究区内燕麦灌溉定额的主要因素(R2为0.515),ET0次之(R2为0.152);其它气象因素中,日照时数对研究区燕麦灌溉定额影响较大(R2为0.462),且呈正相关关系;相对湿度对燕麦灌溉定额影响较小。西藏燕麦主要种植区的灌溉定额及其空间分布可为西藏自治区灌溉用水管理提供支撑。  相似文献   
2.
We collected 469 frontal face images of Ukrainian cabinet ministers who were in office in 2000–2020. For each image, the minister's body mass index was estimated using a computer vision algorithm. The time series of median estimated body mass index of cabinet ministers co-moves over time with two existing measures of corruption – World Bank worldwide governance indicator Control of Corruption, and the discrepancy between the quantity of luxury wristwatches exported from Switzerland to Ukraine (reported by Swiss statistics) and the corresponding quantity imported by Ukraine from Switzerland (reported by Ukrainian statistics).  相似文献   
3.
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   
4.
Family firms bear two types of agency costs, including type I and type II agency problems, in corporate environmental practices: (1) Outside executives at family firms hesitate to engage in environmental strategies, which can lead to drops in profits; (2) Controlling families employ opportunistically environmental management to achieve their interests. We argue that a primary cause for the agency problems lies on ineffective internal corporate governance at family firms, which can cause loss of managerial (or power) balance between outside executives and family executives. Our findings show that family firms with ownership and strategic control (FSC), which family executives and outside executives monitor and constrain each other, can achieve the highest environmental performance. Moreover, external controls, including product market competition and provincial environmental regulations, substitute effective internal control of FSC. The environmental performance premium of FSC is more prevalent when the production market competition is lower. Family firms with ownership, operational, and strategic control (FOSC) can achieve higher environmental performance within a province with more stringent environmental regulations.  相似文献   
5.
6.
基于动态能力理论和权变理论,以IT-业务融合、双元环境为调节变量,探究大数据能力与企业创新绩效间的作用关系,结果发现:大数据能力对创新绩效具有正向促进作用;IT-业务融合调节大数据能力与创新绩效的关系,IT-业务融合水平越高,大数据能力对创新绩效的正向影响就越显著;双元环境能够调节大数据能力与创新绩效间关系。其中,环境动态性在大数据能力与创新绩效关系间起正U型调节作用,而环境竞争性在大数据能力与创新绩效关系间起倒U型调节作用。从内外部情境视角解释大数据能力的创新转化,对中国企业大数据应用具有指导意义。  相似文献   
7.
Prior research has shown that the well-being of employees engaged in intensive work can vary with the discretion their jobs afford regarding how and when to carry out the work. This article explores a different avenue. It argues that well-being also varies with employees’ individual motives for working intensively. The article introduces self-determination theory to the domain of work intensity and focuses on two hypotheses. The first is whether intensive work driven by explicit or implicit incentives is more positively associated with an employee's job satisfaction than intensive work driven by job demands. The second is whether intensive work driven by intrinsic motives is more positively associated with job satisfaction than that driven by explicit or implicit incentives. In both these cases, the article also examines whether equivalent effects exist on (reduced) quit intentions. Original data from a major Greek grocery chain provide corroborative evidence that is robust to a rich set of covariates, including increasingly demanding adjustments for job discretion. The findings contribute to a more complete understanding of why differences in well-being exist among employees performing intensive work, with implications for workers and employers.  相似文献   
8.
Peng  Jing  Yu  Lei  Zhong  Xiang  Dong  Tiansong 《Water Resources Management》2022,36(3):1043-1055
Water Resources Management - The low impact development (LID) concept aims to control storm runoff and pollution through decentralized, small-scale source control to bring the development area as...  相似文献   
9.
We investigate the impact of housing wealth, credit availability and financial distress on college enrolment decisions. We find that housing wealth is negatively related to enrolment in public schools and positively related to enrolment in private schools. This evidence suggests that, on average, students substituted away from private schools towards public institutions during the recent financial crisis.  相似文献   
10.
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