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921.
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This study compares the evolution of container port systems in China and the USA in terms of port throughput, number of container ports and the concentration level in the container port system, based on the time-series data on these three features over the period 1979–2009 for China and 1970–2009 for the USA. The results show that the densities of container ports in the two countries are similar, and their evolutionary processes are alike, which has led to a comparable market structure in the port industries of the two countries. In addition, the disparities between container ports closely represent the unevenness in the regional economic development. We further compare the port management regimes of the two countries in terms of the administrative processes for port development and expansion, the ownership structure and the providers of port functions, which offer some explanation on the dynamics of port evolution in the two countries. In conclusion, it can be seen that the evolution of the container port system and the management regime in the USA can be a de facto reference for the future development of the Chinese container port system. 相似文献
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925.
This study employs back-propagation neural networks (BPN) to improve the forecasting accuracy of air passenger and air cargo demand from Japan to Taiwan. The factors which influence air passenger and air cargo demand are identified, evaluated and analysed in detail. The results reveal that some factors influence both passenger and cargo demand, and the others only one of them. The forecasting accuracy of air passenger and air cargo demand has been improved efficiently by the proposed procedure to evaluate input variables. The established model improves dramatically the forecasting accuracy of air passenger demand with an extremely low mean absolute percentage error (MAPE) of 0.34% and 7.74% for air cargo demand. 相似文献
926.
Several route choice models are reviewed in the context of the stochastic user equilibrium problem. The traffic assignment problem has been extensively studied in the literature. Several models were developed focusing mainly on the solution of the link flow pattern for congested urban areas. The behavioural assumption governing route choice, which is the essential part of any traffic assignment model, received relatively much less attention. The core of any traffic assignment method is the route choice model. In the wellknown deterministic case, a simple choice model is assumed in which drivers choose their best route. The assumption of perfect knowledge of travel costs has been long considered inadequate to explain travel behaviour. Consequently, probabilistic route choice models were developed in which drivers were assumed to minimize their perceived costs given a set of routes. The objective of the paper is to review the different route choice models used to solve the traffic assignment problem. Focus is on the different model structures. The paper connects some of the route choice models proposed long ago, such as the logit and probit models, with recently developed models. It discusses several extensions to the simple logit model, as well as the choice set generation problem and the incorporation of the models in the assignment problem. 相似文献
927.
V. N. Ivanov 《运输评论》2013,33(4):353-368
Abstract Solution of current and future transportation problems requires a more consistent and complete realization of the principles of socioeconomic motivation in research and practical work. With this aim it is suggested that a transport‐communication model (TCM) of society should be constructed as a projection of all the social processes into the space of artificial flows of matter, energy and information. A simplified example of a transport‐communication systems model in terms of mathematical systems theory is reviewed, demonstrating the constructs of such an approach, and a critical analysis is made of scientific paradigms, used in the transportation theory. The author suggests an iterative procedure for the formation of a hierarchic theory of transportation systems based on simulation concepts and experiments, and formulates a hypothesis of its feasibility in the construction of present‐day transportation theory as a realistic basis for solving transportation problems. 相似文献
928.
Jos N. van Ommeren Derk WentinkPiet Rietveld 《Transportation Research Part A: Policy and Practice》2012,46(1):123-130
The literature on car cruising is dominated by theory. We examine cruising for parking using a nation-wide random sample of car trips. We exclude employer-provided and residential parking. We focus on the Netherlands, where levels of on-street and off-street parking prices are locally the same. We demonstrate then that due to this price setting the average cruising time in the Netherlands is only 36 s per car trip. Furthermore, we show that cruising is not random. It is more common in (large) cities that receive more car trips, particularly for shopping and leisure activities. Cruising time increases with travel duration as well as with parking duration. Cruising has a distinctive pattern over the day with a peak in the morning, so the order of arrival is essential to parking. Because cruising has a spatial and time component, policies may be considered that reduce cruising time through flexible pricing of parking or improved information about vacant parking spaces. 相似文献
929.
响应面法模拟轴肩和搅拌针形状对铝合金搅拌摩擦的影响(英文) 总被引:1,自引:0,他引:1
The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics. 相似文献
930.
重点介绍与某港区燃料油码头输油管线相配套的集肤效应电伴热系统的工作原理.实践证明,集肤效应电伴热系统可替代现有的蒸汽伴热系统,且具有运营成本低、运行安全、维护方便、节能效果显著等优势.集肤效应电伴热技术代表着今后的技术发展方向. 相似文献