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   2285篇
  免费   239篇
  国内免费   23篇
财政金融   79篇
工业经济   209篇
计划管理   987篇
经济学   233篇
综合类   244篇
运输经济   13篇
旅游经济   12篇
贸易经济   339篇
农业经济   143篇
经济概况   288篇
  2024年   27篇
  2023年   52篇
  2022年   78篇
  2021年   94篇
  2020年   88篇
  2019年   45篇
  2018年   44篇
  2017年   45篇
  2016年   55篇
  2015年   130篇
  2014年   192篇
  2013年   211篇
  2012年   212篇
  2011年   280篇
  2010年   258篇
  2009年   113篇
  2008年   129篇
  2007年   98篇
  2006年   103篇
  2005年   76篇
  2004年   45篇
  2003年   36篇
  2002年   21篇
  2001年   37篇
  2000年   35篇
  1999年   12篇
  1998年   4篇
  1997年   10篇
  1996年   3篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
排序方式: 共有2547条查询结果,搜索用时 62 毫秒
51.
周义超 《价值工程》2015,34(9):207-208
本文结合某高速公路黄河特大桥X#墩的施工,介绍了液压爬模系统及爬模施工工艺在薄壁高墩建设中的应用,为今后高墩的施工积累经验。  相似文献   
52.
Recent research has emphasised that an increasing number of enterprises need computation environments for executing HPC (High Performance Computing) applications. Rather than paying the cost of ownership and possess physical, fixed capacity clusters, enterprises can reserve or rent resources for undertaking the required tasks. With the emergence of new computation paradigms such as cloud computing it has become possible to solve a wider range of problems due to their capability to handle and process massive amounts of data. On the other hand, given the pressing regulatory requirement to reduce the carbon footprint of our built environment, significant researching efforts have been recently directed towards simulation-based building energy optimisation with the overall objective of reducing energy consumption. Energy optimisation in buildings represents a class of problems that requires significant computation resources and generally is a time consuming process especially when undertaken with building simulation software, such as EnergyPlus. In this paper we present how a HPC based cloud model can be efficiently used for running and deploying EnergyPlus simulation-based optimisation in order to fulfil a number of objectives related to energy consumption. We describe and evaluate the establishment of such an application-based environment, and consider a cost perspective to determine the efficiency over several cases we explore. This study identifies the following contributions: (i) a comprehensive examination of issues relevant to the HPC community, including performance, cost, user perspectives and range of user activities, (ii) a comparison of two different execution environments such as HTCondor and CometCloud and determine their effectiveness in supporting simulation-based optimisation and (iii) a detailed performance analysis to locate the limiting factors of these execution environments.  相似文献   
53.
Abstract

This study aimed to investigate the role that a professionalized context plays in shaping employee reactions to talent management decisions. We examined the mediating role of felt obligation in the relationship between talent ratings and organizational citizenship behavior. Further, the study tested whether professional identification moderates the relationship between talent ratings and felt obligation towards the organization. Five hundred and ninety-eight teachers that had recently received ratings of their talent status responded to a survey questionnaire. Felt obligation mediated the relationship between talent ratings and organizational citizenship behavior. Furthermore, professional identification moderated the relationship between ratings of potential and felt obligation in such a way that the relationship was strongest for the teachers expressing the lowest professional identification. At high levels of professional identification, the relationship was not significant. These results indicate that conventional talent management might be less effective for increasing favorable attitudes and behaviors among employees in highly professionalized contexts, such as the education sector.  相似文献   
54.
Abstract:

In this paper, we provide a comparison of two models of temperature-based weather derivatives. The Alaton et al. model (2002) and the continuous-time autoregressive (CAR) model of Benth et al. (2007) are applied to temperature data from twelve cities in China. The objective is to determine which is the better model for temperature derivative modeling in Chinese cities. We found the CAR model to be more accurate in terms of normality of residuals and smaller relative errors. However, the shortcomings of both the Alaton et al. model and the CAR model are revealed in this study as well.  相似文献   
55.
以稻谷粤农丝苗为原材料,置于4种不同储藏模式下,具体如下:(1)15℃储藏240d。(2)30℃储藏240d。(3)以15℃为开端,与30℃交替储藏(60d交替1次)至240d。(4)以30℃为开端,与15℃交替储藏(60d交替1次)至240d。每隔60d检测1次,比较上述4种储藏模式下,稻米蒸煮品质和α-淀粉酶活力的变化趋势。研究结果表明:随着时间的延长和储藏温度的升高,稻米品质下降;在实验时间内,以低温为开端的变温模式的稻米品质要优于以高温为开端的变温模式,但差距逐渐减小。  相似文献   
56.
2018年以来中国经济平稳运行,物价水平稳定,就业形势整体向好,经济增长质量稳步提升。不过,当前中国经济仍然面临一定的下行压力,尤其需要警惕消费增速过快下滑、宏观税负进一步加重、民间投资复苏乏力、部分企业效益状况显著恶化、去杠杆过程中金融体系不稳定性加剧等主要风险点。此外,杠杆率高企是现阶段中国经济面临的突出问题,而且中国的杠杆率在不同部门之间以及各部门内部均体现出明显的结构性特点。为此,中央在2018年专门提出了“结构性去杠杆”的新思路。在“结构性去杠杆”稳步推进的大背景下,宏观政策既要积极应对经济下行压力,谨防去杠杆带来的经济增速超预期下滑风险,又要激发经济内生增长动力,促使经济实现长期可持续发展和“高质量发展”。  相似文献   
57.
本文研究了水轮发电机定子穿心螺杆由于自身的涡流损耗而造成的温升情况,并分析了3种穿心螺杆的绝缘结构,得出了最佳的绝缘结构方案。  相似文献   
58.
通过对全封闭单托辊输送机的创新的优化设计,使得此设备在原有的设计基础上,在清扫器、单托辊、靴型料斗、头部耐磨衬板和轴承测温系统等方面进行进一步优化,使之在使用方面更加可靠,维护保养更加方便,实现了该设备的使用性能的又一次飞跃。  相似文献   
59.
张朝  雷同飞 《价值工程》2015,34(9):49-51
本文主要研究了一种基于温差发电的混合动力自行车,并就其改装和发动机尾气余热利用的系统优化设计进行了集中分析,最终得出了相关结论。  相似文献   
60.
谢颖 《科技与企业》2014,(14):150-151
针对国内外电厂对缆式线型感温的设计要求,突出了线型感温探测的重要性。从光纤感温探测的原理开始,对整套系统进行了结构性研究。主要研究了系统结构、探测光缆、控制器等组件。结合拉曼散射原理,剖析温度变化引起探测光缆的吸收和反吸收效应;强调了光学感温探测系统的应用优势和安装条件等。最后结合实体项目,分析对比了传统感温电缆和光学感温探测系统在实际工程应用中的优缺点,并提出了优化方案,以提高火灾报警系统的工作效率。  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