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Despite the pivotal importance of link performance functions to models of transport systems, relatively little work has been done on practical aspects of estimating these functions from observed data. Furthermore it is difficult to find any examples in the literature of estimated urban link performance functions faithfully reproducing theoretical travel time-flow relationships. One reason for the paucity of research in this area is the difficulty and expense of obtaining the requisite data. The increase in automatic collection of traffic flow data goes part way to resolving this problem, but matching such flows to manually recorded travel times can present considerable statistical difficulties in the estimation procedure. This paper considers the estimation of link performance functions from a combination of automatically recorded traffic counts and travel collected by hand, using a non-standard statistical methodology. The study is motivated by a set of data of precisely this type, from the UK city of Leicester. 相似文献
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A new transportation system is described. CyberTran is a steel wheel on rail system designed to travel on elevated guideways, utilizing large numbers of 6 to 20 passenger automated vehicles weighing less than 10,000 pounds. The benefits from these light weight vehicles include dramatically reduced system cost and increased passenger appeal. The system described has been prototyped and tested at the Idaho National Engineering and Environmental Laboratory, a U. S. Department of Energy Research and Development Laboratory. 相似文献
146.
The present paper presents the necessary crack growth statistics and suggests stochastic models for a reliability analysis of the fatigue fracture of welded steel plate joints. The reliability levels are derived from extensive testing with fillet-welded joints for which the entire crack growth history has been measured, not only the final fatigue life. The statistics for the time to reach given crack depths are determined. Fracture-mechanics-derived crack growth curves are fitted to the measured experimental curves and the best fit defines the growth parameters involved for each test specimen. The derived statistics and distribution function for these parameters are used as variables in a Monte Carlo simulation (MCS). In addition a Markov model is developed as an alternative stochastic model. It is a Markov chain for which the discrete damage states are related to chosen crack depths in the material. This model works directly with the experimental time statistics. It is a “stochastic bulk approach” not involving any random variables or fracture mechanics modeling. Both models are fitted to the data base and scaled to in-service conditions. Both methods are compared and discussed. The aim is to provide data for the variables used in a MCS and to develop a Markov chain for fast reliability calculation, especially when predicting the most likely influence of numerous future inspections. 相似文献
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This paper evaluates the development of prospects for cruising in Europe. It examines this within the broad framework of economic theory and maritime economics. Initially, the market structures and relationships applicable to cruising are considered with particular attention being paid to the linkages between the shipping markets and tourism and leisure. This conceptual analysis suggests that whilst cruising has a strong shipping element it does not fall exclusively within the classic framework of maritime economics but draws from both shipping and tourism and leisure. For reasons of clarity, a number of definitions are also provided covering maritime tourism and leisure, cruising, and supply and demand, as it relates to cruising. Following this, an overview of the cruise industry is included. This focuses primarily on the growth in the demand both world wide and at regional level. In particular, the analysis places the development of cruising in Europe in market perspective. Subsequently, the development of cruising in the UK is examined as a case study. Initially, UK market growth is analysed and it can be seen that the UK is now the second largest cruise market in the world after North America. Projections of the growth in UK demand to 2003 are also provided. The growth in supply is also studied and the UK targeted fleet is identified. In addition, the question of ownership is addressed. The prospects of employment for UK seafarers within the cruise industry are also considered and results obtained from the analysis suggest that it should be possible to increase the participation of UK and other European seafarers within the cruise industry at all levels and in all departments. In the final section of the paper, the position of UK ports as terminals and destinations is evaluated. It is concluded that the fundamentals of the cruise business remain strong, and continued growth by the industry should be possible for the foreseeable future. 相似文献
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With the rapid growth of seaborne commodity trades, port development and management has become a challenging issue to the government, enterprise and academia. To alleviate pressures on spatial demand and the environment, sustainable development and scientific management of a port is of crucial importance for its investment, construction and operation. In this article, a research path based on throughput estimation is proposed. The container port of Tianjin could expect to face immense, increasing pressure in the future several years. To meet future increasing capacity requirement, constructing new waterway and berths in a bigger contiguous area or new locations becomes a crucial strategy. Moreover, the strategy of accommodating peak seasonal traffic means existing container terminals have to attain higher output by redesigning their high-precision schedule, reconfiguring terminal topology, improving worker efficiency and employing more modern container-handling facilities. 相似文献
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Robert Pomeroy John Parks Kathleen Reaugh-Flower Mar Guidote Hugh Govan Scott Atkinson 《Coastal management》2015,43(3):301-328
Combating illegal and destructive resource exploitation in the Coral Triangle is central to ensuring the long-term effective management of fisheries, marine protected areas, and climate change adaptation efforts. This article presents results of an investigation of the perceived level of local compliance and enforcement with marine resource rules and regulations and evaluates the effectiveness or potential for community-supported enforcement efforts in the Coral Triangle region. The findings are consistent with those of the literature on compliance and enforcement that any compliance and enforcement system must not only use deterrence, but also be perceived by fishers as being legitimate, fair, accountable and equitable and the need for developing a personal morality and a social environment that supports compliance. There is an opportunity to strategically build on shared value and cultural norms that can promote collaborative fisheries management as a mechanism to increase compliance through non-coercive efforts. Strengthening the long-term capacity for consistent delivery of local support to marine management and enforcement will increase local compliance rates through time. 相似文献