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101.
102.
L. Xin V.L. Markine I.Y. Shevtsov 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(3):301-327
A three-dimensional (3-D) explicit dynamic finite element (FE) model is developed to simulate the impact of the wheel on the crossing nose. The model consists of a wheel set moving over the turnout crossing. Realistic wheel, wing rail and crossing geometries have been used in the model. Using this model the dynamic responses of the system such as the contact forces between the wheel and the crossing, crossing nose displacements and accelerations, stresses in rail material as well as in sleepers and ballast can be obtained. Detailed analysis of the wheel set and crossing interaction using the local contact stress state in the rail is possible as well, which provides a good basis for prediction of the long-term behaviour of the crossing (fatigue analysis). In order to tune and validate the FE model field measurements conducted on several turnouts in the railway network in the Netherlands are used here. The parametric study including variations of the crossing nose geometries performed here demonstrates the capabilities of the developed model. The results of the validation and parametric study are presented and discussed. 相似文献
103.
该文进行了一个三维有限元参数量化的粘弹性路面响应研究,由于不同的轮胎配置:双轮和宽基轮胎在3种温度(5、25和40℃)和两种速度(8、72 km/h);还有影响路面响应的3种因素:移动车轮荷载幅值(连续,梯形),层间界面条件(简单的摩擦和粘弹性模型)和横向力共同对路面响应的影响进行了研究.研究发现连续加载幅值,不但可以模拟路面对运动轮荷载的响应,并且是一种比目前使用的梯形荷载幅值更准确的研究模型.粘弹性模型极大地提高了双轮胎对预测路面的响应,而简单的摩擦模型更接近宽基轮胎的实地测量.侧向剪力是积极改善预测轮底的表面磨损和底部热拌沥青(沥青)基层的较小程度上的应变.研究表明:使用连续加载幅值和非均匀压力分布模拟移动轮,侧向剪切力和适当的界面摩擦可显著改善有限元模型对车辆加载路面响应的预测能力. 相似文献
104.
W. Z. Zhao Y. J. Li C. Y. Wang Z. Q. Zhang C. L. Xu 《International Journal of Automotive Technology》2013,14(6):913-919
The differential steering system (DSS) of electric wheel vehicle gets rid of the restrictions of traditional steering system completely. As an ideal steering technology, it not only realizes the perfect combination of the road feel and the steering portability, but also realizes the harmony and unification between the steering maneuverability and safety. The structure and basic theory of the DSS of electric wheel vehicle are discussed in this paper. Based on these, the dynamic model of the steering system is built. Considering of the uncertainties and disturbances existing in the model, the H∞ mixed sensitivity control theory is applied to achieve better tracking performance and road feel in the process of steering. Then, a H∞ mixed sensitivity controller is designed to restrain the effect of the road disturbance and model uncertainties. The simulation results indicate that the DSS with the designed controller can effectively restrain the effect of noises and disturbances caused by random motivation from road, torque sensor measurement and model parameter uncertainty, and enable the driver to obtain satisfactory road feel. 相似文献
105.
106.
为把好锚杆的锚固质量关,开发简便、准确的无损检测方法是当务之急。介绍锚杆质量的无损检测原理、检测方法、检测分析与判断以及工程应用实例。 相似文献
107.
随着交通运输事业的快速发展,过去修建的桥梁,承受着大量超载车辆和超大交通量的沉重负荷,出现了各种各样的病害.根据近年对公路桥梁的维修加固实践,总结了一些公路桥梁的病害及维修加固的方法. 相似文献
108.
F. Payri A. J. Torregrosa A. Broatch L. Monelletta 《International Journal of Automotive Technology》2009,10(6):761-769
Combustion noise in passenger cars powered with direct injection (DI) diesel engines is frequently the main reason why end-users
are reluctant to drive this type of vehicle. Thus, the great potential of diesel engines for environment preservation — due
to their lower CO2 emissions — could be missed. This situation worsens with the current design trends (engine downsizing) and the emerging new
diesel combustion concepts (Homogeneous Charge Compression Ignition-HCCI, Premixed Charge Compression Ignition-PCCI, etc.),
which are intrinsically noisy. This negative feature can be even more critical in transient operation due to the contribution
of the temporal changes of both source and transmission path on engine noise. Therefore, combustion noise must be considered
as an additional essential factor in engine development, together with performance, emissions and driveability. Thus, suitable
evaluation procedures that can be integrated into the global engine development process in a timely and cost-effective manner
are imperative. Regarding the evaluation procedures, most of the work available in the literature addressed combustion noise
at steady operation. To surpass this limitation, two possible approaches — adapted from the classical and multiple regression
methods — for the overall level assessment of combustion noise in transient conditions are evaluated in this paper. 相似文献
109.
针对铁路5T系统(红外线轴温探测系统、货车运行状态地面安全监测系统、货车滚动轴承早期故障轨边声学诊断系统、货车运行故障动态图像检测系统、客车运行安全监控系统)中的监测数据传输冲突和数据堵塞问题,以各种类型监测数据所反映出的安全程度为依据,建立5T系统信息模型,应用消息队列技术设计基于消息的动态优先队列传输流程,在量化优先因子影响因素的基础上建立基于数据类型、预警等级、车型和车速的数据传输优先模型,将对优先因子的求解转化为对部分权重信息下多目标决策模型的求解,建立单目标优化模型以求解优先模型中未确定的权重向量,根据求解得到的优先因子按照优先队列调整步骤进行传输队列调整.对据此开发的监测数据传输原型系统实验结果表明,所提出的技术方案可行且有效. 相似文献
110.
T.J. Andersen L.C. Lund-Hansen M. Pejrup K.T. Jensen K.N. Mouritsen 《Journal of Marine Systems》2005,55(3-4):123-138
This study was carried out to describe the difference in erodibility and aggregation in a tidal basin including both subtidal and intertidal study sites and to use these results to explain the shifting erosion/deposition cycles at the sites. Erosion thresholds, erosion rates and settling velocities of the eroded material were measured at a mudflat transect and at sediment cores taken from a nearby tidal channel during surveys made in May 2000 and March 2002. Surface samples were analysed for grain-size, chl. a content, faecal pellet content, dry bulk density and organic content. Additionally, surface samples were taken at eight occasions in the period January 2002 to May 2003 from shallow tidal channels in the area. These samples were analysed for mud content and showed that major shifts in sediment distribution occurred in the period. The erodibility of the mudflat was generally high due to pelletization by the mudsnail Hydrobia ulvae but close to the salt marsh much lower erodibility was found, probably due to stabilisation by microphytobenthos. In contrast, the erodibility of the channel bed seemed to be very little influenced by biological activity and the relatively low erodibility found here was caused by physical characteristics of the sediment. The sediment eroded from the mudflat was generally strongly pelletized and showed high settling velocities whereas less aggregation and lower settling velocities were found for the channel bed sediments. Temporal variations of the mudflat stability and hydrodynamics resulted in temporal variations of deposition and erosion and the changing stability at the mudflat is likely to be one of the main reasons for a general transport of fine-grained sediment from the mudflat to the channel in the cold seasons and vice versa during the rest of the year. 相似文献