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   1504篇
  免费   103篇
  国内免费   6篇
财政金融   53篇
工业经济   148篇
计划管理   729篇
经济学   94篇
综合类   153篇
运输经济   61篇
旅游经济   21篇
贸易经济   204篇
农业经济   39篇
经济概况   111篇
  2024年   2篇
  2023年   14篇
  2022年   25篇
  2021年   35篇
  2020年   34篇
  2019年   25篇
  2018年   36篇
  2017年   28篇
  2016年   34篇
  2015年   69篇
  2014年   172篇
  2013年   130篇
  2012年   174篇
  2011年   208篇
  2010年   151篇
  2009年   70篇
  2008年   94篇
  2007年   57篇
  2006年   56篇
  2005年   48篇
  2004年   40篇
  2003年   28篇
  2002年   20篇
  2001年   16篇
  2000年   12篇
  1999年   9篇
  1998年   3篇
  1997年   1篇
  1996年   5篇
  1995年   5篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   3篇
  1990年   3篇
  1989年   1篇
  1982年   1篇
排序方式: 共有1613条查询结果,搜索用时 31 毫秒
91.
The assessment of methodologies to prioritise the construction of new high-speed rail (HSR) corridors has recently become a key issue for transport planners in countries like the U.S., where HSR does not exist. In a climate of financial instability since the onset of the global crisis of 2007–2008, support for new projects is being eroded by serious concerns over the extremely steep costs of high-speed rail, and there is a need for the scientific clarification of the procedure for prioritizing construction.In 2009 a new ranking methodology was developed and applied to 30,000 city pairs in the U.S. to determine their suitability for high-speed rail investment. The existing literature on ranking tools for prioritising HSR corridors is practically non-existent, and, as none of these U.S. lines has been built or put into in operation, this methodology has not been validated. The main aim of this paper is to contribute to these ranking models and highlight their importance in the HSR planning process. The preliminary ranking tool described in this work has been validated using data from the current HSR Spanish network. The results confirm the consistency of the model as a first approach to ranking pairs, mainly for the top O–D relations; however the model has some drawbacks chiefly due to the type of variables used, and their assigned weightings. Finally, some specific improvements are proposed for this ranking approach in order to provide policymakers with a useful tool when planning the construction of new HSR networks.  相似文献   
92.
Zika virus is a mosquito-borne disease that spreads very quickly in different parts of the world. In this article, we proposed a system to prevent and control the spread of Zika virus disease using integration of Fog computing, cloud computing, mobile phones and the Internet of things (IoT)-based sensor devices. Fog computing is used as an intermediary layer between the cloud and end users to reduce the latency time and extra communication cost that is usually found high in cloud-based systems. A fuzzy k-nearest neighbour is used to diagnose the possibly infected users, and Google map web service is used to provide the geographic positioning system (GPS)-based risk assessment to prevent the outbreak. It is used to represent each Zika virus (ZikaV)-infected user, mosquito-dense sites and breeding sites on the Google map that help the government healthcare authorities to control such risk-prone areas effectively and efficiently. The proposed system is deployed on Amazon EC2 cloud to evaluate its performance and accuracy using data set for 2 million users. Our system provides high accuracy of 94.5% for initial diagnosis of different users according to their symptoms and appropriate GPS-based risk assessment.  相似文献   
93.
This paper proposes a monitoring framework to be used during the planning stage for a sports mega-event. The research identifies a lack of monitoring and evaluation studies during the development stage for sports mega-events. Importantly, it notes the absence of research which evaluates an event systematically from the outset of the process and from the perspectives of host residents and event planners. The framework was developed on the basis of the philosophical approach of pragmatism; it focused on a sustainable development perspective, and it was applied to a case study of the Kaohsiung 2009 World Games. A survey of the views of 606 host residents about the potential impacts of the event revealed that the respondents tended to show higher levels of agreement on the host benefits. The results of 38 interviews with various stakeholders indicated big gaps in both the city's long-term development aspirations and the Games themselves and also in the event strategies adopted. Using this information, key sustainability issues can be identified and monitored during the event planning stage so that the desirable outcomes of events can be enhanced and then sustained in the longer term.  相似文献   
94.
根据编码模式生成机理的不同,对单帧编码结构先进行了新分类,分析了技术特点及发展趋势.M阵列编码是一种典型的单帧模式,设计了一种基于M阵列的单帧符号编码结构光模式.重建目标实验表明,可以获得物体较为光滑、完整的三维形廓,丰富、拓展了单帧结构光技术.  相似文献   
95.
张晓雅 《价值工程》2012,31(13):76-78
轨道精调是无砟轨道施工中最关键的一道工序,它对轨道的线型最终位置能否达到设计及验标的要求起着决定性的作用。本文根据广珠城际客运专线无缝线路轨道静态调整施工作业,对采用轨检小车进行轨道静态精调作业的施工组织、设备配置运用和技术方案进行了总结和归纳,形成了CPIII的复测与平差、施工人员系统培训、精调作业、复测与二次精调的基本作业流程。  相似文献   
96.
This paper has been written in response to the Viewpoint contribution by the author Button (2012) entitled: “Is there any economic justification for high-speed railways in the United States?”. In this article, the Spanish HSR high-speed rail network is used as an argument against certain HSR investments. Several of the data presented by the author are misleading and some of the information given in connection with Spain is incomplete. As the Journal of Transport Geography is widely read by policymakers and the scientific community, Button’s misrepresentation could cause serious damage. We therefore set out to clarify the data used by Kenneth Button and to explore some points in greater detail, although in no case eschewing criticism of Spain. Although excessive Spanish investment in public infrastructure over the last twenty years has probably had a negative impact on the real estate bubble, investments in HSR infrastructure in Spain have specifically been accompanied by two particular facts that need to be distinguished from other countries’ experience. These facts cannot be overlooked and will be discussed in this paper. They relate firstly to the total amount of European funds used in HSR construction and secondly to the technological and scientific innovations developed in Spain linked to the HSR market.  相似文献   
97.
师秀凤 《价值工程》2011,30(16):32-33
文章介绍了如何运用步进顺控指令和状态编程法来实现天塔之光控制系统的程序设计,最后设计的程序用状态转移图来表示。  相似文献   
98.
董刚 《价值工程》2010,29(7):251-252
通过对秦皇岛经济发展现状的深刻分析提出其发展中存在基础设施不完善、企业规模较小、海洋经济发展缓慢的问题,针对这些存在的问题和秦皇岛目前发展的实际情况提出打造以轻工业为产业支柱,以港口建设和开发旅游资源为发展两翼的经济战略模式。  相似文献   
99.
光线是电视艺术的基础,没有了光线也就没有了电视艺术。在电视艺术创作中只有充分认识光线的性质,了解直射光、散射光、顺光、侧光和逆光带来的不同视觉效果,才能充分发挥光线在表现时空、刻画人物、强化环境气氛中的造型作用,为电视艺术创作服务。  相似文献   
100.
This paper uses cluster analysis, a form of a posteriori market segmentation, to understand the attitudes of tourists and the local community towards using the Looe Valley Branch Railway Line. The research revealed five segments of users distinguished by their attitudes towards using the train. Following this, the paper discusses the implications of the survey findings for attracting more people to use the Looe Valley Line. It sets its findings in the context of the sustainable tourism aims of reducing transport congestion and emissions, as well as recent work on assessing the scope for sustainable transport development in the leisure and tourism markets.  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