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   263篇
  免费   36篇
财政金融   24篇
工业经济   34篇
计划管理   82篇
经济学   22篇
综合类   17篇
运输经济   3篇
旅游经济   4篇
贸易经济   78篇
农业经济   13篇
经济概况   22篇
  2024年   1篇
  2023年   6篇
  2022年   4篇
  2021年   12篇
  2020年   18篇
  2019年   14篇
  2018年   8篇
  2017年   7篇
  2016年   11篇
  2015年   12篇
  2014年   12篇
  2013年   35篇
  2012年   29篇
  2011年   21篇
  2010年   15篇
  2009年   9篇
  2008年   12篇
  2007年   18篇
  2006年   11篇
  2005年   12篇
  2004年   4篇
  2003年   6篇
  2002年   4篇
  2001年   1篇
  2000年   4篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1993年   3篇
  1992年   1篇
  1988年   1篇
  1983年   1篇
排序方式: 共有299条查询结果,搜索用时 15 毫秒
1.
This paper reviews some recent blockchain‐based applications for information capture, distribution and preservation. As part of that review, this paper examines two key concerns with current blockchain designs for accounting and supply chain transactions: data independence and multiple semantic models for the same information distribution problem. Blockchain applications typically integrate database, application and presentation tiers all in the same ledger. This results in a general inability to query information in the ledger and other concerns. Further, since most applications appear to be private blockchain applications, there is a concern of agents needing to accommodate multiple blockchains depending on who their trading partners are and what they request. Finally, this paper uses a distributed database to design a ‘blockchain‐like’ system for virtual organizations.  相似文献   
2.
In this paper characterizations of negative multinomial distributions based on conditional distributions have been studied.  相似文献   
3.
基于网格计算技术提出了一种分布式的有限元并行计算网格系统的原型DPFEM的构建方法.探讨了DPFEM的系统设计目标,系统平台,软件配置以及系统运作机制.  相似文献   
4.
物流信息系统对物流现代化影响的探讨   总被引:3,自引:0,他引:3  
阐述了现代物流与传统物流的区别,分析服务和信息技术对现代物流的作用,研究提高物流信息系统性能的途径,提出了物流技术新概念。  相似文献   
5.
Calculating the probability of the corresponding significance point is important for finite sample sizes. However, it is difficult to evaluate this probability when the sample sizes are moderate to large. Under these circumstances, consideration of a more accurate approximation for the distribution function is extremely important. Herein, we performed a saddlepoint approximation in the upper tails for the distribution of the sum of independent non‐identically uniform random variables under finite sample sizes. Saddlepoint approximation results were compared with those for a normal approximation. Additionally, the order of errors of the saddlepoint approximation was derived. © 2014 The Authors. Statistica Neerlandica © 2014 VVS.  相似文献   
6.
In this study, the association between information and communication technology (ICT) intensity in firms and labour productivity is explored across 14 European countries for the years 2001–2010. ICT intensity is approximated by the proportion of broadband internet-enabled employees, a novel indicator measuring not only adoption but also diffusion within and among firms. Data have been retrieved by means of the distributed microdata approach (DMD) from registers on business, trade and education as well as from surveys on production, ICT usage and innovation activities in firms held at the national statistical offices. This pioneering approach allows access to otherwise confidential linked firm-level information in dimensions not earlier available. Pooled OLS estimations based on approximately 400,000 observations in harmonised and representative datasets show that in a majority of countries there is a significant and positive relationship between the proportion of broadband internet-enabled employees and labour productivity in firms. However, the strength of the relationship varies across countries and industries. Manufacturing firms receive 50% larger estimates than the services firms, while the latter instead experience the positive association more frequently.  相似文献   
7.
Knoblock and Korf have determined that abstraction can reduce search at a single agent from exponential to linear complexity (Knoblock 1991; Korf 1987). We extend their results by showing how concurrent problem solving among multiple agents using abstraction can further reduce search to logarithmic complexity. We empirically validate our formal analysis by showing that it correctly predicts performance for the Towers of Hanoi problem (which meets all of the assumptions of the analysis). Furthermore, a powerful form of abstraction for large multiagent systems is to group agents into teams, and teams of agents into larger teams, to form an organizational pyramid. We apply our analysis to such an organization of agents and demonstrate the results in a delivery task domain. Our predictions about abstraction's benefits can also be met in this more realistic domain, even though assumptions made in our analysis are violated. Our analytical results thus hold the promise for explaining in general terms many experimental observations made in specific distributed AI systems, and we demonstrate this ability with examples from prior research.This research has been sponsored, in part, by the National Science Foundation under grants IRI-9015423 and IRI-9010645, by the University of Michigan Rackham Graduate School, and by a Bell Northern Research Postgraduate Award.  相似文献   
8.
[目的]为了系统地分析遥感技术在农业资源台账建设中的应用潜力。[方法]文章通过文献研究,阐述了农业资源台账的研究现状,分析了农业资源遥感监测数据源与监测技术的发展趋势,研判了当前遥感技术在农业资源台账建设中的应用潜力。[结果](1)农业资源台账的建设内容主要包括农业资源清单、农业资源评价两个方面,具有空间与时间两种属性。(2)农业遥感数据源向着高空间分辨率、高时间分辨率、高光谱分辨率的方向发展,其监测技术向着多源遥感数据融合应用、智能分类、多维海量数据高效计算的方向发展。(3)遥感技术可对农业资源清单中的主要农业自然资源和社会经济资源的信息进行获取,对农业资源组分评价与农业生态系统整体评价也有很大潜力。[结论]总的来看,农业资源台账建设内容不断丰富,遥感技术在农业资源台账建设中的应用能力显著提升,其应用潜力仍有很大的上升空间,对高效开展农业资源台账建设具有积极作用。  相似文献   
9.
语音指导查询与数据自动传输方法   总被引:1,自引:0,他引:1  
我国电子商务刚刚起步,应根据我国电子商务发展的现状,结合发达国家的先进经验,对相应的网上交易涉税问题尽早给予解决。电子商务的商品交易方式、支付方式等都与传统的方式有着很大的不同,这就给税收制度带来了挑战。本文将对电子商务所涉及的税收问题作一论述。  相似文献   
10.
针对非正交两跳多中继协作通信系统中的分布式中继选择问题,提出了一种基于非正 交信道的中继选择准则,简化了系统的设计。分析了其误码率性能,给出了其解析表达式 和以总功率为约束条件下的最优功率分配方案。仿真结果表明,最佳中继选择准则明显优于 传统的中继选择准则,且在最优功率分配方案下,可以获得明显的分集增益,系统的误码率 显著下降。  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