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671.
轨枕空吊对轨枕动态性能的影响 总被引:2,自引:0,他引:2
为研究轨枕空吊对轨枕动态响应的影响,建立了车辆-轨道垂向耦合动力学模型.假设车辆模型为多刚体系统,用Euler梁模拟离散支撑的钢轨,轨枕视为弹性地基上的Euler梁,利用显式积分法求解车辆-轨道非线性动力学方程.结果表明:当轨枕部分悬空或完全悬空时,影响轨枕最大弯矩的位置;轨枕空吊数目越多,轨枕的弯矩越大;轨枕底座的完全悬空对邻近空吊区的轨枕动态行为影响较大. 相似文献
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为了解决谐振耦合拓扑结构不同的非接触电能传输(CPT)系统效率计算方法不统一的问题,通过对4种基本谐振耦合拓扑结构的CPT系统的分析,给出了CPT系统效率计算的一般方法.在此基础上,为提高CPT系统的效率,通过对一种电流型CPT系统的建模,对系统谐振耦合拓扑结构的参数进行了优化设计,实现了该CPT系统高效率的能量输出.最后,以该电流型CPT系统为试验模型,对提出的效率计算方法和优化设计进行了试验验证.结果表明:该电流型CPT系统谐振耦合拓扑结构最大效率的试验结果为92%,而其优化理论值为93%. 相似文献
673.
制动鼓的热-结构耦合分析 总被引:7,自引:2,他引:5
利用大型通用有限元分析软件ANSYS6.1研究了某中型车前轮制动鼓在机械载荷与温度载荷作用下的热-结构耦合问题。通过对制动鼓不同模型的热分析、结构分析和热应力耦合分析说明不同模型和不同载荷对制动鼓的温度分布、变形及热应力的影响。 相似文献
674.
Integration of signal timing estimation model and dynamic traffic assignment in feedback loops: system design and case study 下载免费PDF全文
This paper presents an integrated framework for effective coupling of a signal timing estimation model and dynamic traffic assignment (DTA) in feedback loops. There are many challenges in effectively integrating signal timing tools with DTA software systems, such as data availability, exchange format, and system coupling. In this research, a tight coupling between a DTA model with various queue‐based simulation models and a quick estimation method Excel‐based signal control tool is achieved and tested. The presented framework design offers an automated solution for providing realistic signal timing parameters and intersection movement capacity allocation, especially for future year scenarios. The framework was used to design an open‐source data hub for multi‐resolution modeling in analysis, modeling and simulation applications, in which a typical regional planning model can be quickly converted to microscopic traffic simulation and signal optimization models. The coupling design and feedback loops are first demonstrated on a simple network, and we examine the theoretically important questions on the number of iterations required for reaching stable solutions in feedback loops. As shown in our experiment, the current coupled application becomes stable after about 30 iterations, when the capacity and signal timing parameters can quickly converge, while DTA's route switching model predominately determines and typically requires more iterations to reach a stable condition. A real‐world work zone case study illustrates how this application can be used to assess impacts of road construction or traffic incident events that disrupt normal traffic operations and cause route switching on multiple analysis levels. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
675.
Huang Z.Wu J.Zhang Y.Liu S. 《现代隧道技术》2018,(5):61-71
In order to study the impacts of the transient seepage on the stability of tunnel excavation face during the installation of lining segments, the fluid-solid coupling effect based numerical model of the tunnel excavation face was developed by the finite element software PLAXIS. With adoption of the variablecontrolling approach, the influences of the depth/diameter ratio (the ratio of the buried depth to diameter of the tunnel) and the support pressure ratio (the ratio of the face support pressure to water and soil pressures ahead of the excavation face) on the face stability and ground settlement were investigated, respectively. At same time, the failure modes of the excavation face under the fluid-solid coupling analysis were also discussed. The results show that:1) the transient seepage leads to the development of the soil arching at the front of the excavation face, in which the smaller deformation at the excavation face is achieved, and so less support pressure for the face stability is allowed. While for the plastic analysis without taking into account the effect of transient seepage, a higher support pressure is required to maintain the stability of the excavation face; 2) in the fluid-solid coupling analysis, the depth/diameter ratio has less impacts on the stability of the excavation surface, but has larger impacts on the ground settlement. The larger the depth/diameter ratio, the larger the ground surface settlement and the settlement profile; 3) however, with the combination of the decrease of the support pressure and the impact of transient seepage on the settlement of ground surface, the soil arching effect in front of the excavation face is gradually reduced. The deformation zone at the ground surface is then connected with the deformed part ahead of the tunnel face to form a wedge-shaped soil sliding zone. It is also observed that the wedge-shaped body tends to have a larger funnel-shaped failure mode than that in the plastic analysis without considering the transient seepage. The results show that the transient seepage has a great impact on the stability of tunnel excavation face in the soil condition with high permeability ratio. The fluid-solid coupling analysis should be adopted to evaluate the deformation of excavation face and ground settlement. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
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山区峡谷地区由于受特殊地形地貌条件影响使得其风场十分复杂,这些地区建立的大跨度桥梁面临着更为突出的风致振动问题,而当前规范对峡谷桥梁的抗风设计还没有明确规定。为更加深入认识峡谷风场的分布特性,基于WRF与CFD耦合模式对峡谷桥址风场进行精细化分析,在中尺度气象模式基础上结合多项式插值方法获取入口边界的平均风速,同时对峡谷桥址上游风速进行实时监测,利用实测站脉动特性互等的原则获取数值模拟入口位置的脉动特性。将平均风速和脉动风速综合考虑后利用UDF程序赋给大涡模拟的入口边界并对峡谷桥址位置风场进行详细分析,最后将模拟结果与实测结果的湍流特性进行对比。研究结果表明:考虑脉动风速后的入口边界条件相比于无脉动入口风速其湍流特性与实测值吻合更好;中国现有规范中的标准谱不适用于复杂峡谷桥址地区,如用现有规范设计山区峡谷桥梁,其结果偏不安全;来流风向与峡谷走向是引起加速效应的主要原因,峡谷上游的复杂局部地形是引起峡谷桥址风场多样性的根本原因。研究成果可供山区峡谷大跨度桥梁抗风设计提供参考。 相似文献
679.
将膜盘联轴器简化为多杆模型,基于动态响应特性进行参数等效,建立并求解模型的波动方程。从支反力做功的角度分析膜盘联轴器的减振机理。利用有限元软件进行数值计算,验证数值仿真结果与理论解的一致性。 相似文献
680.