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451.
Multi-echelon distribution strategy is primarily to alleviate the environmental (e.g., energy consumption and emissions) consequence of logistics operations. Differing from the long-term strategic problems (e.g., the two-echelon vehicle routing problem (2E-VRP), the two-echelon location routing problem (2E-LRP) and the truck and trailer routing problem (TTRP)) that make location decisions in depots or satellites, the paper introduces a short-term tactical problem named the two-echelon time-constrained vehicle routing problem in linehaul-delivery systems (2E-TVRP) considering carbon dioxide (CO2) emissions. The linehaul level and the delivery level are linked through city distribution centers (CDCs). The 2E-TVRP, which takes CO2 emissions per ton-kilometer as the objective, has inter-CDC linehaul on the 1st level and delivery from CDCs to satellites on the 2nd level. The Clarke and Wright savings heuristic algorithm (CW) improved by a local search phase is put forward. The case study shows the applicability of the model to real-life problems. The results suggest that the vehicle scheduling provided by the 2E-TVRP is promising to reduce the CO2 emissions per ton-kilometer of the linehaul-delivery system. Adjusting the central depot location or developing the loaded-semitrailer demand among O-D pairs to eliminate empty-running of tractors will contribute to reduce the CO2 emission factor. 相似文献
452.
Arctic sea routes have for long attracted interest from observers and shipping companies because of their shorter distances between the Atlantic and the Pacific. The prevalence of sea ice prevented the real development of a significant traffic, but did not prevent research from trying to assess the economic viability of these routes. With the actual present melting of sea ice in the Arctic, this effort at modeling the profitability of Arctic shipping routes received a new impetus. However, the conclusions of these studies vary widely, depending on the chosen parameters and their value. What can be said of these models, from 1991 until 2013, and to what extent can a model be drawn, capitalizing on twenty years of simulations? 相似文献
453.
水下无人搜探系统装备使用模式分析 总被引:1,自引:1,他引:0
本文从搭载平台、使用水下无人航行器数量、水下无人航行器与母船相对距离、水下无人航行器搜索和探测目标的行动方式、使用人员对水下无人航行器干预程度等几个方面,并结合任务类型和性质,分析提出水下无人搜探系统装备使用模式。 相似文献
454.
U. Hjorth 《Transportation Research Part B: Methodological》1999,33(8):345
From basic assumptions about independent and consistent driver behaviour, and with data from traffic counts, we derive statistical properties of regression or correlation estimates of route selection probabilities, turning probabilities and travelling times. Our modelling is conditional in a way that avoids most traffic generation problems and permits an asymptotic analysis of the precision under mild assumptions allowing non-stationarity. This allows us to put together non-stationary data from the corresponding time intervals during several days when we aim at high precision estimates. 相似文献
455.
Introduction Vehicle routing problem (VRP) with differentfleets is an important investment decision in reality. Itconsists of two decision-making processes: selectingvehicles of available types and routing the selectedfleet. A desirable fleet has more than one type of ve-hicles. Typically, the fixed cost of vehicles accountsfor approximately 80% of the total cost associatedwith vehicles[1]. The fixed cost is a major factor todetermine vehicle combination in a fleet.A few models were develope… 相似文献
456.
Introduction Airspace management authority usually partitionsan airspace into several sectors, in each of which acontroller s position is set for the sake of air trafficmanagement and coordination. As air traffic flowrises, the number of aircrafts in each… 相似文献
457.
458.
李兴 《大连铁道学院学报》2006,27(2):46-50
对多机并行模糊调度问题以及禁忌搜索算法的邻域、禁忌表和搜索策略进行研究,提出一种求解该问题的带回溯追踪结构的禁忌搜索算法,该算法带有回访跟踪功能,对未访问的历史解的邻域继续搜索.仿真结果证明了算法的有效、可行. 相似文献
459.
基于下降搜索的量子进化算法 总被引:2,自引:0,他引:2
马淑霞 《西南交通大学学报》2004,39(3):390-393
为了提高全局寻优能力和收敛速度,基于量子进化算法和混合遗传算法,提出了一种新的进化算法.该算法将下降搜索理论应用到量子进化算法中,改进了量子进化算法仅靠量子门进行迭代的作用,从而加快了收敛速度,并降低了个体在进化时产生退化的可能性.典型函数的仿真实验结果表明,该算法具有好的全局性和收敛性. 相似文献
460.
ZENG Qing-cheng YANG Zhong-zhen 《船舶与海洋工程学报》2007,6(2):44-50
An optimization model for scheduling of quay cranes (QCs) and yard trailers was proposed to improve the overall efficiency of container terminals. To implement this model, a two-phase tabu search algorithm was designed. In the QCs scheduling phase of the algorithm, a search was performed to determine a good QC unloading operation order. For each QC unloading operation order generated during the QC's scheduling phase, another search was run to obtain a good yard trailer routing for the given QC's unloading order. Using this information, the time required for the operation was estimated, then the time of return to availability of the units was fed back to the QC scheduler. Numerical tests show that the two-phase Tabu Search algorithm searches the solution space efficiently, decreases the empty distance yard trailers must travel, decreases the number of trailers needed, and thereby reduces time and costs and improves the integration and reliability of container terminal operation systems. 相似文献