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151.
驼峰堰临界淹没度(hs/H0)cr计算探讨 总被引:1,自引:0,他引:1
禹华谦 《西南交通大学学报》1996,31(1):105-108
本文从数学力学原理出发,对驼峰堰淹没流太判别进行探讨,得到了驼峰堰临界淹没度(hs/H0)cr的理论计算式,可供实际工程参用。 相似文献
152.
胡必锦 《重庆交通学院学报》2006,25(6):162-164
Markov模型在标准文本和手写文字的自动识别领域中有特别重要的应用.在讨论如何由观测数据来估计模型参数的问题中,代替Baum辅助函数采用模型的熵特性引入判断函数,并利用此判断函数获得模型参数的重估算法. 相似文献
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155.
运用随机平均法对轮对系统的随机分叉行为进行研究,对比亚临界和超临界分叉2种典型轮对系统随机动态分叉的差异,分析动态分叉与Hopf分叉的区别,定义全局随机临界速度,提出新的失稳判定方法。结果表明,随机激扰对轮对系统的稳定性影响很大,在随机激扰的作用下,轮对系统的临界速度会随着随机激扰的强度增大而显著降低,当轮对仅受轨道随机激励时随机激扰对稳定性的影响不大,但遇到大风等强激扰环境时,随机激扰的影响将不可忽视。随机动态分叉点对应的速度可作为全局随机临界速度,且最大Lyapunov指数法可作为新的失稳判定方法。 相似文献
156.
基于采用MHB对旧水泥混凝土路面实施碎石化破碎工艺在决策、设计、施工与质量控制等环节不够全面、深入,结合多个工程实践,提出了碎石化工艺应用决策标准,研究成果可为旧水泥路碎石化改造提供指导. 相似文献
157.
158.
Kho Shahriar Iqbal Gabriele Bulian Kazuhiko Hasegawa Md. Mashud Karim Zobair Ibn Awal 《Journal of Marine Science and Technology》2008,13(3):282-290
On the basis of previous studies, a series of hazards involving the typical small inland passenger ferries operating in inland
Bangladeshi waters have been identified. In particular, stormy weather conditions, overloading, and the risk of crowding to
one side have been determined as the typical events that are likely to lead to capsizing in the intact condition. In this
article, possible hazard mitigation measures are discussed, both from the regulatory and from the design point of view, for
a small inland ferry that is very similar to one that actually capsized in the past. The addressed design options involve
ballasting and hull modification by means of additional buoyancy above the waterline. From a regulatory point of view, it
is proposed that the present weather criterion in force in Bangladesh be modified by increasing the wind speed to be accounted
for and by considering the concurrent effects of wind, rolling, and the crowding of people to one side. 相似文献
159.
In support of the development of improved fillet weld sizing criteria for lightweight shipboard structures, a comprehensive static strength test program using longitudinal and transverse shear specimens according to AWS B4.0 Standards has been conducted. This test program covers base material with strength ranging from 71 ksi (490 MPa) to 96 ksi (660 MPa) and weld size ranging from 1/8″ (3 mm) to 3/8″ (10 mm). This paper focuses on a traction stress based analysis of the test data as an effort to establish a unified shear strength definition for load-carrying fillet weld specimens regardless of shear loading conditions. The proposed shear strength definition proves to be effective in correlating the fillet weld strength test data of the longitudinal and transverse shear specimens. The results of this investigation demonstrate that existing shear strength definitions used by various weld sizing criteria such as those given by Class Societies have two major limitations: (1) it cannot be related to a critical stress state on experimentally observed failure plane in transverse shear specimens; (2) it underestimates shear stress at failure due to severe stress concentration at weld end in typical longitudinal shear specimens. These two limitations have been shown to be the major cause for having two significantly different shear strength values: one is transverse shear strength obtained from transverse shear specimens and the other is longitudinal shear strength obtained from longitudinal shear specimens. 相似文献
160.
Alfonso M. Panunzio Guillaume Puel Régis Cottereau Samuel Simon Xavier Quost 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2018,56(11):1768-1795
This paper investigates the effects of the track geometry irregularities on the wheel–rail dynamic interactions and the rail fatigue initiation through the application of the Dang Van criterion, that supposes an elastic shakedown of the structure. The irregularities are modelled, using experimental data, as a stochastic field which is representative of the considered railway network. The tracks thus generated are introduced as the input of a railway dynamics software to characterise the stochastic contact patch and the parameters on which it depends: contact forces and wheelset–rail relative position. A variance-based global sensitivity analysis is performed on quantities of interest representative of the dynamic behaviour of the system, with respect to the stochastic geometry irregularities and for different curve radius classes and operating conditions. The estimation of the internal stresses and the fatigue index being more time-consuming than the dynamical simulations, the sensitivity analysis is performed through a metamodel, whose input parameters are the wheel–rail relative position and velocity. The coefficient of variation of the number of fatigue cycles, when the simulations are performed with random geometry irregularities, varies between 0.13 and 0.28. In a large radius curve, the most influent irregularity is the horizontal curvature, while, in a tight curve, the gauge becomes more important. 相似文献