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451.
文章介绍了HXD1B型机车供风及制动系统主要技术部件及其特点参数、主要功能,详细阐述了空电联合制动的模式. 相似文献
452.
航空货物运量分形预测及R/S分析 总被引:1,自引:0,他引:1
航空货运量预测是航空公司运力安排的重要参考。本文根据分形拼贴定理,由分形插值方法求取一个吸引子与航空货运量历史数据相近的迭代函数系统,建立分形预测模型,对航空货运量进行预测。预测结果表明,该方法不存在收敛性问题,数据收集简单,具有较好的实用性。货运量时间序列R/S分析进一步表明了预测值的合理性。 相似文献
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This paper deals with developing a methodology for estimating the resilience, friability, and costs of an air transport network affected by a large-scale disruptive event. The network consists of airports and airspace/air routes between them where airlines operate their flights. Resilience is considered as the ability of the network to neutralize the impacts of disruptive event(s). Friability implies reducing the network’s existing resilience due to removing particular nodes/airports and/or links/air routes, and consequently cancelling the affected airline flights. The costs imply additional expenses imposed on airports, airlines, and air passengers as the potentially most affected actors/stakeholders due to mitigating actions such as delaying, cancelling and rerouting particular affected flights. These actions aim at maintaining both the network’s resilience and safety at the acceptable level under given conditions.Large scale disruptive events, which can compromise the resilience and friability of a given air transport network, include bad weather, failures of particular (crucial) network components, the industrial actions of the air transport staff, natural disasters, terrorist threats/attacks and traffic incidents/accidents.The methodology is applied to the selected real-life case under given conditions. In addition, this methodology could be used for pre-selecting the location of airline hub airport(s), assessing the resilience of planned airline schedules and the prospective consequences, and designing mitigating measures before, during, and in the aftermath of a disruptive event. As such, it could, with slight modifications, be applied to transport networks operated by other transport modes. 相似文献
456.
船舶舱室空气污染物是影响舱室舒适性的重要因素。以极地邮轮舱室空气污染物为研究对象,在分析其来源及相互影响因素的基础上,提出了采用因子分子法对舱室污染物进行降维的处理方法。进一步,基于相关样本数据的基础上,分别利用SPSS软件和MATLAB编程进行了污染物的因子分析。目前已有的样本数据显示公因子为两个:第一公因子在CO、细菌总数、可吸入颗粒物、甲醛和SO2上有较大的载荷;第二个公因子在甲醛、NO2和SO2上有较大的载荷。研究结果表明:SPSS软件和MATLAB在降维分析中研究结论一致。该研究结果可为对环境舒适度要求较高的船舶舱室空气污染物主动控制提供较好的理论依据和参考。 相似文献
457.
Determinants of the willingness-to-pay for reducing the environmental impacts of road transportation
Fernando Lera-López Javier FaulinMercedes Sánchez 《Transportation Research Part D: Transport and Environment》2012,17(3):215-220
This paper examines the willingness-to-pay of people living in a number of villages in Navarre, in the Spanish Pyrenees to reduce noise and air pollution. Several models are used for estimation based on contingent valuation, noting that those living near roads are willing to pay more to reduce air and noise pollution. In addition, younger people, the better educated, and the more environmentally aware individuals are also willing to pay more to reduce those externalities. 相似文献
458.
Hanif D. Sherali Justin M. Hill 《Transportation Research Part C: Emerging Technologies》2009,17(6):631-641
In this paper, we consider a particular class of network flow problems that seeks a shortest path, if it exists, between a source node s and a destination node d in a connected digraph, such that we arrive at node d at a specified time τ while leaving node s no earlier than a lower-bounding time LB, and where the availability of each network link is time-dependent in the sense that it can be traversed only during specified intervals of time. We refer to this problem as the reverse time-restricted shortest path problem (RTSP), and it arises, for example, in the context of generating flight plans within air traffic management approaches under severe convective weather conditions. We show that this problem is NP-hard in general, but is polynomially solvable under a special regularity condition. A pseudo-polynomial time dynamic programming algorithm is developed to solve Problem RTSP, along with an effective heap implementation strategy. Computational results using real flight generation test cases as well as random simulated problems are presented. 相似文献
459.
A. McNabola B.M. Broderick L.W. Gill 《Transportation Research Part D: Transport and Environment》2009,14(8):567-575
The influence of inter-vehicle spacing on the in-vehicle air pollution exposure of car commuters in heavy traffic conditions was investigated, both experimentally and numerically. An experimental investigation was carried out into the effect, on in-vehicle air pollution exposure, of maintaining a distance of approximately 2 m to the preceding vehicle in congested idling traffic conditions compared to that of an identical vehicle maintaining a distance of approximately 1 m. In-vehicle VOC and PM2.5 concentrations revealed that a 19–31% reduction in exposure at the larger inter-vehicle spacing. A computational fluid dynamics model was calibrated using the experimental data and used to prediction car exposure under different conditions by varying certain key parameters. Agreement between the experimental and predicted data of 82% was achieved. The results show a significant drop in pollutant concentrations occurred within the first 2 m of their emission from the preceding vehicles exhaust. 相似文献
460.