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81.
用FRP加固混凝土桥梁的方法已很普及,但它会导致结构延性下降,即超脆性破坏,分析和试验证明,将全长粘贴FRP改为只粘贴两端而中部不粘贴的部分区段粘贴法,可以改善被加固结构的延性。 相似文献
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对重庆地区公路沥青路面使用性能进行调研检测,利用现有的评价指标对调查路段的路面破损状况和路面行驶质量进行了评价.在此基础上,结合该地区高温多雨的气候特征和路面使用坏境,对路面使用性能评价指标中的路面状况指数PCI和路面结构承载力指数PSSI进行完善和修订,以便因地制宜对西南山区公路沥青路面使用性能进行科学评价. 相似文献
84.
带扰动观测器的船舶轨迹跟踪自适应动态面滑模控制 总被引:1,自引:1,他引:0
针对遭受未知外部环境扰动的三自由度全驱动船舶轨迹跟踪控制问题,设计一种带扰动观测器的自适应动态面滑模控制方法。该方法构造扰动观测器估计未知扰动,并对控制量进行前馈补偿,采用σ修正泄漏项的自适应律估计扰动观测误差的界以提高控制精度,结合动态面技术解决传统反演法的微分爆炸问题,并选取李雅普诺夫函数证明该控制器可保证闭环系统内所有信号的一致最终有界性。基于一艘供给船舶进行仿真试验,结果表明,所设计的控制器输出合理有效且跟踪精度高,在工程实际中具有一定的参考价值。 相似文献
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In 2013, the concept of the ‘Silk Road Economic Belt and the 21st-Century Maritime Silk Road (Belt and Road)’ was initiated by the Chinese government, which involves Asian, European and African continents and their adjacent seas. Logistics plays a core role in such a large framework of economy and trade. In recent years, China, European Union, and Southeast Asia pay much attention to the design and development of the intermodal transportation network towards both economic and environmental efficiency. In this paper, we propose an empty container repositioning model in the intermodal transportation network of Belt and Road (B&R) Initiative by considering both standard and foldable containers. In this model, empty containers are repositioned from the inland of the original area, such as China, to other areas of B&R Initiative related countries and regions, such as European Union and Southeast Asia. We develop a mixed integer linear programming model to determine the optimal repositioning of empty containers via the intermodal transportation network. An Artificial Bee Colony algorithm is developed to solve large size problems in practice and numerical experiments are conducted to show the efficiency of our proposed algorithm. We provide managerial insights regarding the impact on the network performance of foldable containers transportation. 相似文献
87.
Yui-yip Lau Ka-chai Tam Adolf K. Y. Ng Zhang Jing Jiejian Feng 《Maritime Policy and Management》2018,45(3):403-417
China’s Belt and Road (BR) initiative is expected to facilitate international trade between the countries involved. In this study, we review the special requirements of wine logistics and the market growth potential of wine consumption in China. A model minimizing generalized logistical costs is developed and applied to wine imports in China, so that the best candidate cities in which to locate transport gateways and distribution centers can be identified. Our analysis suggests that the most preferred gateways are Shanghai, Tianjin, Guangzhou, and Hong Kong, which all have similar delivery costs. In comparison, Beijing and Chongqing have much higher delivery costs, mainly because they do not have good access to marine transport and/or efficient domestic distribution networks. For long-distance intercontinental transport of large volumes of wine, marine shipping remains the only viable delivery mode. However, wine distribution within China extensively uses air, road, and water transport. Therefore, cities with excellent multi-modal transport services are better positioned to become wine logistics gateways. Our study also highlights the importance of value-added services and good government support, which are important factors that influence distribution costs and quality. 相似文献
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Sofia Grahn-Voorneveld 《Transportation Research Part A: Policy and Practice》2012,46(4):645-651
Usually transport systems, and roads in particular, are viewed as public goods. However, this is not always the case. In Sweden a large part of the road system is privately owned. Most of these privately owned roads are rural roads used by farmers and summer cottage owners, or used for forest transport. These roads are mainly provided by ownership associations.An important difference between public roads and these privately owned roads is that all investments- and maintenance decisions are made by the users themselves, who also have to pay the costs, whereas the usual case is that the owners/providers of a road-system are different agents than the users. Here the question is not how to charge the roads but how to split the costs of the roads among the users in an efficient and “fair” way.The motivation of this paper is the practical problem of how such an ownership association can divide the costs for the road network among the members in an efficient and “fair” way. The problem is treated from a game theoretical point of view, making use of the Shapley value. This means that the problem is associated with a game - a mathematical representation of the conflict situation. The Shapley value is a very important solution concept for cooperative games, like the game in this case. For games corresponding to this specific type of problems, it is shown that the Shapley value has excellent properties, such as beeing an element of the core, and beeing very easy to compute. 相似文献
90.
James E. Larsen 《Transportation Research Part D: Transport and Environment》2012,17(4):317-320
This study investigates the relationship between surface street traffic volume and single-family house prices in a relatively small city in the US. Hedonic price models are estimated using data from 9670 transactions that occurred between January 1998 and March 2011. It is discovered that parcels fronting or adjacent to a high-traffic street sell, on average, at an 8.1% discount compared to similar parcels that are not so situated. Restricting the analysis to parcels on or adjacent to a high-traffic street, house price and traffic volume are found to be negatively related; a doubling of volume from any particular traffic count, ceteris paribus, reduces selling price by an average of 2.1%. 相似文献