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391.
Marijonas Bogdevicius Gintautas Bureika Stasys Dailydka 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(5):689-705
The simplified method to determine a vertical impact force of wheel with flat and rail interaction is presented in this article. The presented simplified method can be used to identify maximum contact force and its distribution in the contact length between the damaged wheel and the rail. The vertical impact force depends on geometrical parameters of the rail and wheel with flat, speed of vehicle and the angle of deviation of rail. This article demonstrates the influence of wheel with flat geometrical parameters, speed of vehicle to maximum contact force and its distribution in the contact zone. The obtained values of the simplified method for determination of a vertical contact force are compared with the results obtained from field measurements. 相似文献
392.
Ken Takagi 《Journal of Marine Science and Technology》2006,11(2):100-110
The diffraction and radiation problems of a two dimensional multihull structure were investigated by application of the scattering
matrix theory. The scattering matrix theory is widely used to analyze wave interaction problems in various scientific fields.
The research is focused on the zeros of the wave exciting force near resonance, which occurs both in the diffraction problem
and the radiation problem. At the zeros of the wave exciting force, the wave exciting force for the overall structure is zero,
but each demihull undergoes wave excitation. At near-resonant frequencies, the amplitude of the traveling wave between adjacent
demihulls becomes very large and the demihulls experience very large wave forces. A number of simple equations for representing
the hydrodynamic properties of the multihull structure at the zeros and near-resonant frequencies are obtained. Numerical
examples show that these simple equations well explain the hydrodynamic forces and the wave system in the spaces between the
demihulls. 相似文献
393.
高桩码头-岸坡相互作用有限元数值模拟 总被引:2,自引:0,他引:2
高桩码头-岸坡体系的相互作用机理一直是困扰工程界的难题。基于某突堤的现场勘察资料和土体参数,建立了高桩码头与岸坡相互作用的二维平面应变问题和三维空间问题的弹塑性有限元模型,采用与M ohr-Co lum n准则匹配的D rucker-P rager准则作为土的屈服准则,分析了桩基-岸坡体系的变形机理,同时,针对二维和三维情况各种工况组合进行了对比分析,并结合土体参数和现场测斜资料,分析了高桩码头-岸坡体系的变形规律,并指出了影响桩、梁和岸坡体系变形的主要因素,并建议了合理的治理方案。 相似文献
394.
舰载无人机战术控制系统研究 总被引:4,自引:4,他引:0
无人机以其特点已在战场中扮演着举足轻重的角色,随着无人机技术的飞速发展,必须研制通用的无人机战术控制系统(TCS),实现对各类无人机的操控,并将无人机系统与舰艇C^4I系统有效集成。对美军无人机战术控制系统发展情况进行了简要描述,系统地分析了舰载见人机战术控制系统的功能、交互等级和系统组成,并阐述了系统运行方式: 相似文献
395.
396.
397.
In this paper, a 3D time domain technique is adopted to calculate the coupled hydrodynamic interaction between two bodies without flare in waves. For verifying the code, two same cylinders are selected to calculate coupled hydrodynamic effects by comparison with the results obtained by 3D frequency method which has been proved to be efficient for solving such problems. In order to improve efficiency of calculation, the effect of history time has been discussed, and an improved method is presented. Moreover, the effect of lateral separation distance is also discussed in detail. The technique developed here may serve as a more rigorous tool to analyze the related transient problems of two ships doing underway replenishment in waves. 相似文献
398.
介绍了一种山区道路拓宽技术——整体式悬挑结构,运用有限元软件数值模拟了岩土对荷载的响应,提出了其简化计算方法;用visual c++编写了一种适用于该结构的计算程序,对该结构与岩土的共同作用进行了研究;得出了不同土体对结构受力的影响,实际工程选用老填土和碎石土是经济的. 相似文献
399.
目前膨胀土中桩基设计仍基于非膨胀土力学的设计原则。基于FLAC3D采用热-力耦合方法实现吸热膨胀来模拟膨胀土的吸湿膨胀,并重点阐述温度场模拟湿度场的关键参数取值方法。建立膨胀土中单桩三维实体模型,得出渗水作用下膨胀土中单桩的荷载变形特性、桩侧摩阻发挥特征,并分析了桩长、桩径、膨胀系数等对单桩承载特性的影响规律。研究结论:非扩底桩最小桩长宜大于2倍膨胀影响深度;细长桩比短粗桩更能有效降低膨胀土中桩顶的位移。该方法可获得渗水作用下任一时刻的桩身受力变形特性,为研究膨胀土中桩基受荷性能提供一种可行的变通手段。 相似文献
400.
Description of a flexible and extendable physical–biogeochemical model system for the water column 总被引:1,自引:0,他引:1
Hans Burchard Karsten Bolding Wilfried Kühn Andreas Meister Thomas Neumann Lars Umlauf 《Journal of Marine Systems》2006,61(3-4):180
A modelling system for coupled physical–biogeochemical simulations in the water column is presented here. The physical model component allows for a number of different statistical turbulence closure schemes, ranging from simple algebraic closures to two-equation turbulence models with algebraic second-moment closures. The biogeochemical module consists of models which are based on a number of state variables represented by their ensemble averaged concentrations. Specific biogeochemical models may range from simple NPZ (nutrient–phytoplankton–zooplankton) to complex ecosystem models. Recently developed modified Patankar solvers for ordinary differential equations allow for stable discretisations of the production and destruction terms guaranteeing conservative and non-negative solutions. The increased stability of these new solvers over explicit solvers is demonstrated for a plankton spring bloom simulation. The model system is applied to marine ecosystem dynamics the Northern North Sea and the Central Gotland Sea. Two different biogeochemical models are applied, a conservative nitrogen-based model to the North Sea, and a more complex model including an oxygen equation to the Baltic Sea, allowing for the reproduction of chemical processes under anoxic conditions. For both applications, earlier model results obtained with slightly different model setups could be basically reproduced. It became however clear that the choice for ecosystem model parameters such as maximum phytoplankton growth rates does strongly depend on the physical model parameters (such as turbulence closure models or external forcing). 相似文献