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   23798篇
  免费   1033篇
  国内免费   350篇
财政金融   1941篇
工业经济   1351篇
计划管理   6867篇
经济学   3313篇
综合类   2209篇
运输经济   357篇
旅游经济   717篇
贸易经济   4994篇
农业经济   1286篇
经济概况   2146篇
  2024年   80篇
  2023年   405篇
  2022年   426篇
  2021年   635篇
  2020年   874篇
  2019年   720篇
  2018年   637篇
  2017年   784篇
  2016年   752篇
  2015年   765篇
  2014年   1380篇
  2013年   2126篇
  2012年   1771篇
  2011年   2116篇
  2010年   1461篇
  2009年   1287篇
  2008年   1982篇
  2007年   1727篇
  2006年   1481篇
  2005年   1165篇
  2004年   830篇
  2003年   550篇
  2002年   365篇
  2001年   232篇
  2000年   168篇
  1999年   123篇
  1998年   75篇
  1997年   66篇
  1996年   46篇
  1995年   26篇
  1994年   14篇
  1993年   15篇
  1992年   19篇
  1991年   8篇
  1990年   8篇
  1989年   6篇
  1988年   6篇
  1987年   1篇
  1986年   3篇
  1985年   7篇
  1984年   8篇
  1983年   9篇
  1982年   12篇
  1981年   7篇
  1980年   1篇
  1979年   1篇
  1973年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
介绍了未来高速移动通信新标准IEEE802.20的总体概况,具体分析了IEEE802.20的技术特性、系统参考结构以及系统的组成模型,并对IEEE802.20标准前景分析与展望进行了详细描述。  相似文献   
62.
Cost of equity estimates are compared for three pricing models: the traditional local CAPM, the single (market) factor global CAPM, and the two‐factor global CAPM, with both market and currency index factors. For 2989 US stocks, the average difference in the cost of equity estimates is about 48 basis points between the local CAPM and the single‐factor global CAPM, and is about 61 basis points between the two global models. For 70 developed‐market ADRs, the corresponding average differences are 76 and 47 basis points, respectively. For 48 emerging‐market ADRs, the corresponding average differences are 57 and 70 basis points.  相似文献   
63.
The principal aim of this paper is to evaluate the impact of the future European high-speed train network on accessibility, by reducing time distance between places and modifying their relative location. We compare the current situation with that foreseen for the year 2010, according to the Outline Plan of the European High-Speed Train Network, in order to analyse which areas will most benefit from construction and improvement of the infrastructure. It is hypothesized that the high-speed train will certainly bring the peripheral regions closer to the central ones, but will also increase imbalances between the main cities and their hinterlands. A weighted average distance indicator is applied for this purpose. This measure identifies the spatial distribution of accessibility in the area of study, emphasizing the infrastructure effects, and locates accessibility changes at the European level. A Geographic Information System (GIS) has been used to carry out this study.  相似文献   
64.
本文首先讲述了ITS中的2种通信技术——专用短程通信(DSRC)和蜂窝数字分组数据网(CDPD)的基本概念、工作原理及系统特点等,然后提出了一种基本这2种通信技术的先进公交系统,并对各个子系统的功能结构进行了描述。  相似文献   
65.
Lejeune  Miguel A. 《NETNOMICS》2002,4(2):145-162
Denial of Service (DoS) attacks consist of overwhelming a server, a network or a Web site in order to paralyze its normal activity. The additional parameter in Distributed Denial of Service (DdoS) attacks is the distributing strategy. It means that DDoS attacks do not come from a single computer but stem from all accessible channels and servers. Consequences are multiple, ranging from system errors, temporary inability to access the Web site for normal users to challenging the actual reliability of the Internet. Despite this, Internet users show carelessness. The explanation lies in the specificities of DDoS attacks. We explore possibilities to raise users' awareness about the actual amplitude of problems caused by DDoS attacks. We suggest a careful examination of Internet pricing mechanisms and switching from flat to usage-constraining pricing schemes.  相似文献   
66.
The selective principle of mutually exclusive project is the maximum of net present value, It is difficult to make decision when NPVA is equal to NPVLB. Some assistant analyses are put forward in "Enterprise Investment Decision Management". The scientific marginal analysis shows that the assistant analyses including the duration analysis are wrong. This problem can be solved by the classical marginal analysis.  相似文献   
67.
Based on the analysis of the need of a new coordinating mechanism in cyber-value chain, this paper puts forward a cyber-coordinating mechanism, which is a mechanism between market mechanism and firm hierarchical mechanism. It is the theoretical basic point for setting up the system of Strategic Management Accounting in cyber-value chain. This paper conducts the model of Strategic Management Accounting based on cyber-coordinating mechanism, and presents evidence from a case study that was conducted to understand the impact of disintegration on original suppliers and of reintegration on new suppliers in order to support our cyber-coordinating mechanism hypothesis and the application value of the new model of strategic management accounting in cyber-value chain.  相似文献   
68.
近几年的几场局部战争部分表明了现代军事航天系统的重要性。本文主要介绍了美国最重要的一个军事航天测控网--空军卫星控制网的情况,希望能对了解美国军事航天测控体制有所帮助。  相似文献   
69.
介绍价值网的概念及应用情况,探讨铁路多经物流企业构建及实施价值网经营模式的必要性和可行性,构建了铁路多经物流企业的价值网经营模式,为探索铁路多经物流企业的发展模式提供一种选择方式。  相似文献   
70.
本文系统地归纳了在科技文献中常见的涉及到倍数增减的结构及其表达方式  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