全文获取类型
收费全文 | 561篇 |
免费 | 23篇 |
专业分类
公路运输 | 149篇 |
综合类 | 293篇 |
水路运输 | 59篇 |
铁路运输 | 47篇 |
综合运输 | 36篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 21篇 |
2020年 | 16篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 42篇 |
2013年 | 30篇 |
2012年 | 36篇 |
2011年 | 64篇 |
2010年 | 50篇 |
2009年 | 50篇 |
2008年 | 43篇 |
2007年 | 50篇 |
2006年 | 43篇 |
2005年 | 19篇 |
2004年 | 8篇 |
2003年 | 11篇 |
2002年 | 3篇 |
2001年 | 11篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 5篇 |
1989年 | 1篇 |
排序方式: 共有584条查询结果,搜索用时 62 毫秒
471.
472.
复杂系统的可靠性数据分散、混杂,传统方法难以得出有效的分析结论。贝叶斯网络模型能够描述部件间相互关系与系统影响程度的变化趋势,较适于建立可靠性分析模型。为此,以某型导弹末制导雷达为实例,通过不同条件下两种贝叶斯网络模型(静态与动态)的比较分析,较为详细地给出故障诊断与致因影响等结论,并验证了模型的有效性。 相似文献
473.
474.
475.
476.
为了提高交通信息定价精度,在假定出行者权衡出行时间和出行费用双目标路径诱导的基础上,建立混合均衡定价模型,通过实例对模型进行了标定和验证,对比评价了单目标和双目标路径诱导下的交通信息定价策略,并给出双目标路径诱导下的交通信息定价结果。研究结果表明,与双目标路径诱导相比,单目标路径诱导改变了交通信息定价的可行区域,当具有信息的出行者、交通信息提供者、交通管理者三方各自的利益为决策主体时,交通信息的最终价格分别为1.3、2.6和1.8元,说明了混合均衡定价模型是有效的。 相似文献
477.
交通拥挤漂移的形成机理与预防技术 总被引:1,自引:0,他引:1
为了研究交通诱导信息对驾驶员驾驶行为的影响,从诱导比例、替代路径数量、替代路径合理性和路网交通负荷分布的角度,分析了在动态交通诱导条件下拥挤漂移现象的产生机理,提出了逐步增加诱导比例,在路阻数据中加入干扰因子与K最短路方法等3种预防交通拥挤漂移的技术,并采用Vissim交通仿真软件对其进行了模拟评价。模拟结果表明:在局部拥挤的道路网络中,所提出的3种方法都能够减轻或消除拥挤漂移现象,其中K最短路方法的效果最好,其次是逐步诱导方法,尽管在路阻数据中加入干扰因子的方法效果最不理想,但仍优于对车辆进行100%诱导和不采取任何诱导措施的情况。 相似文献
478.
A methodology for optimizing variable pedestrian evacuation guidance in buildings with convex polygonal interior spaces is proposed. The optimization of variable guidance is a bi-level problem. The calculation of variable guidance based on the prediction of congestion and hazards is the upper-level problem. The prediction of congestion provided the variable guidance is the lower-level problem. A local search procedure is developed to solve the problem. The proposed methodology has three major contributions. First, a logistic regression model for guidance compliance behavior is calibrated using a virtual reality experiment and the critical factors for the behavior are identified. Second, the guidance compliance and following behaviors are considered in the lower-level problem. Third, benchmarks are calculated to evaluate the performance of optimized variable guidance, including the lower bound of the maximum evacuation time and the maximum evacuation time under a fixed guidance. Finally, the proposed methodology is validated with numerical examples. Results show that the method has the potential to reduce evacuation time in emergencies. 相似文献
479.
480.
Electric vehicles (EVs) have been regarded as effective options for solving the environmental and energy problems in the field of transportation. However, given the limited driving range and insufficient charging stations, searching and selecting charging stations is an important issue for EV drivers during trips. A smart charging service should be developed to help address the charging issue of EV drivers, and a practical algorithm for charging guidance is required to realise it. This study aims to design a geometry-based algorithm for charging guidance that can be effectively applied in the smart charging service. Geographic research findings and geometric approaches are applied to design the algorithm. The algorithm is practical because it is based on the information from drivers’ charging requests, and its total number of calculations is significantly less than that of the conventional shortest-first algorithm. The algorithm is effective because it considers the consistency of direction trend between the charging route and the destination in addition to the travel distance, which conforms to the travel demands of EV drivers. Moreover, simulation examples are presented to demonstrate the proposed algorithm. Results of the proposed algorithm are compared with those of the other two algorithms, which show that the proposed algorithm can obtain a better selection of charging stations for EV drivers from the perspective of entire travel chains and take a shorter computational time. 相似文献