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   1898篇
  免费   58篇
  国内免费   6篇
财政金融   286篇
工业经济   110篇
计划管理   303篇
经济学   321篇
综合类   98篇
运输经济   17篇
旅游经济   9篇
贸易经济   216篇
农业经济   88篇
经济概况   222篇
水利工程   291篇
邮电经济   1篇
  2024年   4篇
  2023年   16篇
  2022年   22篇
  2021年   47篇
  2020年   52篇
  2019年   46篇
  2018年   35篇
  2017年   61篇
  2016年   50篇
  2015年   45篇
  2014年   63篇
  2013年   127篇
  2012年   135篇
  2011年   226篇
  2010年   162篇
  2009年   137篇
  2008年   135篇
  2007年   107篇
  2006年   123篇
  2005年   116篇
  2004年   36篇
  2003年   28篇
  2002年   27篇
  2001年   27篇
  2000年   18篇
  1999年   32篇
  1998年   7篇
  1997年   14篇
  1996年   10篇
  1995年   7篇
  1994年   11篇
  1993年   6篇
  1992年   8篇
  1991年   3篇
  1990年   9篇
  1989年   2篇
  1987年   1篇
  1986年   1篇
  1983年   3篇
  1977年   1篇
  1975年   1篇
  1964年   1篇
排序方式: 共有1962条查询结果,搜索用时 15 毫秒
1.
Disclosure standards mandate the quantitative disclosure of hedging‐instrument‐related risks but not the disclosure of hedged‐item‐related risks. We examine how a match (mismatch) in formats, caused by making quantitative (qualitative) hedged item disclosures alongside quantitative hedging instrument disclosures, affects investors' integration of information from these two related disclosures. Our first experiment varies the hedged item disclosure format (quantitative or qualitative) and the portion of risk hedged (small or large). We find that when disclosure formats are mismatched, the less comparable nature of the two disclosures caused investors to neglect the offsetting relationship when assessing net risks. As a result, risk and investment judgments were influenced by the more prominent quantitative hedging instrument disclosures. Our second experiment finds that the use of a qualitative debiaser that clarifies the relationship between the two disclosures led to the integration of information and mitigated this effect.  相似文献   
2.
论述质检质机构必须进行计量认证的原因;阐明计量认证不仅是“金字塔牌”,而且认证的过程,同时是本单位昨技术更上一个台阶的过程。计量认证的前后,检测单位的面貌会不大一样。  相似文献   
3.
In this study, four similar bench-scale submerged Anoxic/Oxic Membrane Bioreactors (MBR) were used simultaneously to investigate the effects of solids retention time (SRT) on organic and nitrogen removal in MBR for treating domestic wastewater. COD removal efficiencies in all reactors were consistently above 94% under steady state conditions. Complete conversion of NH(4+)-N to NO(3-)-N was readily achieved over a feed NH(4+)-N concentration range of 30 to 50 mg/L. It was also observed that SRT did not significantly affect the nitrification in the MBR systems investigated. The average denitrification efficiencies for the 3, 5, 10 and 20 days SRT operations were 43.9, 32.6, 47.5 and 66.5%, respectively. In general, the average effluent nitrogen concentrations, which were mainly nitrate, were about 22.2, 27.6, 21.7 and 13.9 mg/L for the 3, 5, 10 and 20 days SRT systems, respectively. The rate of membrane fouling at 3 days SRT operation was more rapid than that observed at 5 days SRT. No fouling was noted in the 10 days and 20 days SRT systems during the entire period of study.  相似文献   
4.
Ultraviolet (UV) disinfection is becoming increasingly popular as an alternative disinfection technology to chlorination in recent years. In this study, we investigated the photoreactivation of Escherichia coli following medium-pressure (MP) UV disinfection of synthetic water by a bench-scale collimated beam apparatus. The UV doses ranged from 1.6 -19.7 mWs/cm2 and photoreactivation was investigated for 6 hours under fluorescent light. In addition, chloramination was applied after UV disinfection to investigate its ability to control photoreactivation. It was found that photoreactivation occurred for all UV doses tested and the increase in bacteria numbers ranged from 0.04 to 1.35 log10. However, the degree of photoreactivation decreased with increased UV doses. Chloramination experiments revealed that the addition of 0.5 mg/l of monochloramine resulted in suppression of photoreactivation for 1 hour only. An increased monochloramine dose of 1 mg/l was found to prevent photoreactivation for the entire duration of the experiment. The results of this study have shown that photoreactivation occurs even after MP UV disinfection, although it is of a lesser extent at higher UV doses. This study has also established that secondary chloramination can effectively suppress and eliminate photoreactivation with a chloramine dose of 1 mg/l.  相似文献   
5.
In this study I contend that the ownership type has a significant impact on the environment–strategy configurations amongst different firms in a transitional economy. The influence of ownership type on the environment–strategy configuration is tested, based on an analysis of surveys of 201 managers from four types of companies in China: state‐owned, collectively‐owned, privately‐owned, and foreign joint ventures. Results support the central notion that each ownership type exhibits a distinct environment–strategy configuration, which in turn has important performance implications for the firms.  相似文献   
6.
浅析石油化工项目产品市场分析   总被引:2,自引:0,他引:2  
市场分析是项目前期的重要工作之一,目前尚未赢得人们足够的重视。国外的投资咨询公司对石油化工项目的产品市场分析有其一套比较完整的操作程序和评估体系,以BOPP为案例介绍了市场分析的思路和方法,并且指出市场分析作为一种新的理念,必须进一步深化和细化,逐步加以完善。  相似文献   
7.
This study investigates the intervening effects of budgetary participation and job-relevant information on the relationship between budget emphasis and job satisfaction. It proposes that budgetary participation and job-relevant information are endogenous to budget emphasis. Using the path analytical technique and based on a sample of 152 senior managers, the study found that budget emphasis has an insignificant direct effect on job satisfaction, but a strong indirect effect through job-relevant information and budgetary participation. The results also indicate that job-relevant information has an intervening effect on the relationship between participation and job satisfaction.  相似文献   
8.
It is mentioned in this paper that the adjustment of flow structure occurs when themain-flow swings.The changes of turbulence structure and flow energy loss in the indoor rivermodel are measured.The experimental data are presented for the first time for the further studyof complicated river flow structure.  相似文献   
9.
This paper investigates how a development moratorium affects choices of development timing and land values in a framework where both the value of developed property evolves stochastically and the development costs are fully irreversible. We assume that a regulator initially announces that land is not allowed to be developed during a finite period of time in the future. A developer, thus, must decide whether to develop land before the timing ordinance is imposed, or after it expires. The development moratorium reduces the developer’s option value from waiting and, thus, accelerates development. We also use simulation analysis to demonstrate how the other factors that relate to the demand and supply conditions of the real estate market affect this accelerating effect.  相似文献   
10.
This article analyzes the impact and effectiveness of the Mexicanlabor retraining program for unemployed and displaced workers—Programade Becas de Capacitación para Trabajadores (PROBECAT).The strategy followed is to compare the post-training labormarket experiences of trainees with those of a comparison group—amatched sample of unemployed individuals who were eligible for,but did not participate in, PROBECAT. The results of this exercisesuggest that participation in PROBECAT reduced the mean durationof unemployment for both men and women trainees and increasedthe monthly earnings of men, but not of women. The results alsoindicate that the post-training earnings effect varied systematicallyby level of education attained, with the largest earnings increases(of about 28 to 37 percent) found for men with six to twelveyears of education.  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