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221.
建立非线性等式和不等式约束规划问题的一个序列二次规划(SQP)型算法.算法的每次迭代只需解一个确实可解的二次规划,然后对其解进行简单的显式校正,便可产生关于罚函数是下降的搜索方向,克服Maratos效应.在适当的假设条件下,还论证了算法的全局收敛性和超线性收敛性. 相似文献
222.
翁競 《湖北汽车工业学院学报》2008,22(3):49-51
罚函数方法是数学规划中一种常见且有效的求解方法。用罚函数原理,把二层线性规划(BLP)下层问题的对偶间隙作为惩罚项,将BLP转化为带罚函数子项的有限个线性规划问题。由于BLP的全局最优解可在约束域S的极点上找到,利用线性规划对偶理论,给出了一种求解该二层线性规划的罚函数算法。 相似文献
223.
基于"基础设施即服务"的理念研究区域城际铁路规划问题,精准考虑带时间窗的个体出行特征和运输服务供给,构建时空网络联系基础设施、服务供给和出行需求3个维度.在所有路段存在的前提下,考虑城际铁路、城市轨道交通和城市道路等基础设施及其运输服务供给,为每类出行者生成满足其出行时间窗的备选出行链集合,以所有出行者广义费用和总投资... 相似文献
224.
We propose the problem of profit-based container assignment (P-CA), in which the container shipment demand is dependent on the freight rate, similar to the “elastic demand” in the literature on urban transportation networks. The problem involves determining the optimal freight rates, the number of containers to transport and how to transport the containers in a liner shipping network to maximize the total profit. We first consider a tactical-level P-CA with known demand functions that are estimated based on historical data and formulate it as a nonlinear optimization model. The tactical-level P-CA can be used for evaluating and improving the container liner shipping network. We then address the operational-level P-CA with unknown demand functions, which aims to design a mechanism that adjusts the freight rates to maximize the profit. A theoretically convergent trial-and-error approach, and a practical trial-and-error approach, are developed. A numerical example is reported to illustrate the application of the models and approaches. 相似文献
225.
Once limited to the military domain, unmanned aerial vehicles are now poised to gain widespread adoption in the commercial sector. One such application is to deploy these aircraft, also known as drones, for last-mile delivery in logistics operations. While significant research efforts are underway to improve the technology required to enable delivery by drone, less attention has been focused on the operational challenges associated with leveraging this technology. This paper provides two mathematical programming models aimed at optimal routing and scheduling of unmanned aircraft, and delivery trucks, in this new paradigm of parcel delivery. In particular, a unique variant of the classical vehicle routing problem is introduced, motivated by a scenario in which an unmanned aerial vehicle works in collaboration with a traditional delivery truck to distribute parcels. We present mixed integer linear programming formulations for two delivery-by-drone problems, along with two simple, yet effective, heuristic solution approaches to solve problems of practical size. Solutions to these problems will facilitate the adoption of unmanned aircraft for last-mile delivery. Such a delivery system is expected to provide faster receipt of customer orders at less cost to the distributor and with reduced environmental impacts. A numerical analysis demonstrates the effectiveness of the heuristics and investigates the tradeoffs between using drones with faster flight speeds versus longer endurance. 相似文献
226.
本文通过线性规划模型以及运用手工计算两种定量方法,给出了在货源、货类较多的情况下,对运输工具进行配载,以求得在充分利用运输工具的额定载重量和限定容积的情况下,同时获得最大的运费收入,从而提高运输企业的效率和效益。 相似文献
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228.
Siu Kei Hwe Raymond K. Cheung Yat-wah Wan 《Transportation Research Part A: Policy and Practice》2006,40(10):918-935
A significant portion of the 200,000 people working in Hong Kong’s central business district (CBD) relies on buses as their primary means of transport. During peak hours, nearly a thousand double-decker buses pour into a tiny area of 150 ha. This causes traffic congestion and air pollution. Moreover, given that the flow is uni-directional (into the CBD in the morning and out of the CBD in the afternoon), the occupancy of buses in the CBD is actually low.In this paper, we propose to reduce traffic congestion and to increase bus occupancy by merging bus routes. We describe the peculiar situation of the CBD in Hong Kong and explain the necessary conditions for the possible success of merging routes. Our analysis shows that merging will lead to an overall benefit for all parties, including government, bus operators, and passengers. The actual merging decisions, which routes to merge and at what frequencies buses should run, are determined by a mathematical model. The model also shows quantitatively the benefits of merging routes and the impacts of other factors. The procedure that we follow and the model that we adopt can be applied to other CBD. 相似文献
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