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   597篇
  免费   46篇
  国内免费   4篇
财政金融   12篇
工业经济   41篇
计划管理   348篇
经济学   30篇
综合类   53篇
运输经济   22篇
旅游经济   2篇
贸易经济   68篇
农业经济   10篇
经济概况   61篇
  2024年   5篇
  2023年   12篇
  2022年   16篇
  2021年   40篇
  2020年   43篇
  2019年   13篇
  2018年   11篇
  2017年   17篇
  2016年   9篇
  2015年   39篇
  2014年   68篇
  2013年   52篇
  2012年   74篇
  2011年   63篇
  2010年   47篇
  2009年   23篇
  2008年   10篇
  2007年   23篇
  2006年   25篇
  2005年   14篇
  2004年   10篇
  2003年   6篇
  2002年   9篇
  2001年   2篇
  2000年   5篇
  1999年   1篇
  1998年   6篇
  1997年   2篇
  1996年   2篇
排序方式: 共有647条查询结果,搜索用时 156 毫秒
1.
Replacing conventional vehicle taxis with electric vehicles would be an efficient measure to reduce greenhouse gas emissions. Due to the limited range and long charging times of current battery electric vehicles, it is of utmost importance to provide sufficient charging facilities. This article analyses the impact of the placement and charging power of charging stations on potential mileage and revenue of electric taxis on the example of Singapore. Therefore, we developed an agent-based electric taxi simulation model to investigate electric taxis’ driving profiles with respect to different vehicle types and charging infrastructure designs. This model is also capable of simulating conventional taxi driving profiles. The validation of these simulation results with real taxi data showed that the model is reproducing taxi driving profiles with high accuracy in great detail. We found out that electric taxis could reach the same mileage and revenue as conventional taxis if charging with a power of 160?kW is possible. Furthermore, we discovered that waiting times for available charging stations have a stronger effect on revenue than the length of detours to reach charging stations. Based on these findings, we concluded that it is more important to reduce waiting times by placing sufficient numbers of charging stations at each location before expanding the charging network by installing small numbers of charging stations at many locations.  相似文献   
2.
Electric vehicles (EV) use an eco-friendly technology that limits the greenhouse gas emissions of the transport sector, but the limited battery capacity and the density of the battery are the major barriers to the widespread adoption of EV. To mitigate this, a good method seems to be the innovative wireless charging technology called ‘On-Line EV (OLEV)’, which is a contactless electric power transfer technology. This EV technology has the potential to charge the vehicle’s battery dynamically while the vehicle is in motion. This system helps to reduce not only the size of the battery but also its cost, and it also contributes to extending the driving range before the EV has to stop. The high cost of this technology requires an optimal location of the infrastructure along the route. For this reason, the objective of this paper is to study the problem of the location of the wireless charging infrastructure in a transport network composed of multiple routes between the origin and the destination. To find a strategic solution to this problem, we first and foremost propose a nonlinear integer programming solution to reach a compromise between the cost of the battery, which is related to its capacity, and the cost of installing the power transmitters, while maintaining the quality of the vehicle’s routing. Second, we adapt the multi-objective particle swarm optimization (MPSO) approach to our problem, as the particles were robust in solving nonlinear optimization problems. Since we have a multi-objective problem with two binary variables, we combine the binary and discrete versions of the particle swarm optimization approach with the multi-objective one. The port of Le Havre is presented as a case study to illustrate the proposed methodology. The results are analyzed and discussed in order to point out the efficiency of our resolution method.  相似文献   
3.
研究目的:设计土地储备智能决策体系,将土地储备决策环节进行科学化、定量化和模型化,为政府合理开展土地储备提供决策依据。研究方法:遵循科学性、实用性、先进性、开放性原则,以数据为驱动,人工智能为核心,通过基于Hadoop/Spark的大数据处理技术、多源异构数据融合技术、智能决策模型集对多源时空大数据挖掘分析。研究结果:提出了土地储备智能决策体系,研究了一套面向土地储备的决策方法集,实现对现状条件的精准刻画,对土地储备规模、结构、时序等内容的科学决策;在此基础上,研发了智能决策支持平台,将数据资源共享、现状条件评估、智能决策专题等功能集成,构建土地储备智能决策"一张图",并实现平台的自我学习和更新。研究结论:应用于宁波市实例验证,该体系有效地促进了土地储备科学智慧决策,对优化土地资源配置具有参考意义。  相似文献   
4.
在交通场景中采用一些预警措施能够有效地减少交通事故发生。例如,对车辆轨迹进行跟踪并预测车辆的驾驶行为,就是一个常用的预警方法。在对车辆进行跟踪的过程中,数据关联是很重要的部分,它可以对车辆的观测点和轨迹进行关联,从而更新车辆的轨迹,完成跟踪过程。在此背景下,提出了一种新的数据关联算法,即k近邻联合概率数据关联算法(k Nearest Neighbor-Joint Probability Data Association,kNN-JPDA)。实验结果表明,该算法能够较好地解决在交通场景下车辆数据的数据关联问题,在精度以及运行效率方面都有所提高。  相似文献   
5.
车辆类型识别方法是智能交通系统的关键技术之一。利用深度学习的高维特征泛化学习能力,将改进的LeNet-5卷积神经网络用于基于交通微波雷达的大小车型分类识别。首先,以雷达触发前的N帧信号为基础,对雷达的回波信号进行分析并构建数据集;然后,分析LeNet-5卷积神经网络的特点;最后提出一种改进的LeNet-5卷积神经网络。实验结果表明,与传统的支持向量机方法相比,所提方法能够智能学习大小车的雷达时频信号特征,大小车型识别准确率达到97%以上,可为交通场景下的车型识别研究提供新的技术途径。  相似文献   
6.
作为物物相连的互联网,物联网通过信息传感设备,把互联网与任何物品相连接,为构建智能交通信号控制与采集的体系提供了可能。论文从基于物联网的智能交通系统整体框架入手,并着重分析其在交通控制和信号采集两个子系统中的运用,指出物联网技术将全面提升交通管理水平。  相似文献   
7.
采用开源免费的深度学习平台,利用python二次开发了“智铸”系统,包括“识铸”“听铸”“盯铸”三个模块,铸造企业员工可以用手机或电脑自主学习,提升员工从业能力。在设备旁安装“听铸”软硬件一体化设备,可以实现对连续运行设备的在线自动监听侦测。“盯铸”模块实现连续生产铸件的自动检测、铸造缺陷分析与重点安全区域的监控。  相似文献   
8.
随着社会大众对金融服务的要求不断增多,银行网点转型已经成为一个必然趋势。信息时代背景下,银行网点的转型大多向智能化的方向转变,而随着网点转型,其客户服务模式也在不断创新。论文以邮储银行大连分行为例,对银行网点智能化转型的影响进行了分析,探究了邮储银行大连分行网点智能化转型存在的问题,并且提出了相关的转型建议,最后对邮储银行大连分行智能化网点转型下客户服务模式的创新情况进行了研究,希望能够在银行网点智能化转型的背景下,促进其客户服务水平的不断提升。  相似文献   
9.
论文对分布式电动汽车充电桩信息安全防护技术进行研究,分析充电桩信息安全防护技术应用,注重提高防护技术应用可行性与安全性。对分布式电动汽车充电桩通行特点进行分析,探究信息安全防护方案。  相似文献   
10.
Intelligent sharing bicycle has been a new fashion in China and appeals to more and more tourists. To better understand the experience of tourists traveling on sharing bicycle, this study explored the influence of perceived benefit of sharing bicycle on different perceived experiences, including escape, entertainment, esthetic and educational experiences. The relationships between these experiences and perceived satisfaction were also tested. An effective questionnaire survey was conducted for 296 tourists in Chengdu, China. The results of the study show that perceived benefit significantly relates to all the four dimensions of experience. However, only entertainment and esthetic experience seem to affect tourist satisfaction in this context. The relationship among educational experience, escape experience and tourist satisfaction are insignificant. Theoretical and practical implications of the study results are discussed for further research.  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