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211.
212.
The ESC system, since its introduction in the mid 90s, has greatly contributed to prevention of vehicle accidents with its capability of maintaining vehicle stability in severe driving conditions. Due to its significant advantages, many nations are now adopting regulations that mandate installation of the ESC system in all classes of passenger vehicles — from mini to luxury. Accordingly it became important to know whether an ESC ECU can yield good performance on a wide range of vehicle parameter changes. In this paper, robustness analysis was conducted to study how characteristic variation of the main chassis components affect the performance of the ESC ECU. This analysis was carried out using a HILS system built on an actual ESC ECU. The variation range of each chassis component was carefully selected considering the component’s design criteria adopted in automotive industries. Based upon the robustness analysis results, the allowable variation ranges of the chassis components for ensuring sound performance of an ESC ECU were proposed.  相似文献   
213.
The particle size distribution and particle number (PN) concentration emitted by internal combustion engine are a subject of significant environmental concern because of their adverse health effects and environmental impact. This subject has recently attracted the attention of the Particle Measurement Programme (PMP). In 2007, the UN-ECE GRPE PMP proposed a new method to measure particle emissions in the diluted exhaust of automotive engines and a regulation limit (<6.0×1011 #/km, number of particles). The specific PN regulation of spark-ignited combustion engine will be regulated starting on September 1, 2014 (EURO 6). In this study, three types of LPG supply systems (a mixer system and a multi-point injection system with gas-phase or liquid-phase LPG fuel) were used for a comparison of the particulate emission characteristics, including the nano-sized particle number density. Each of the three LPG vehicles with various LPG injection systems contained a multi-cylinder engine with same displacement volumes of 2,000 cm3 and a three-way catalytic converter. The test fuel that was used in this study for the spark-ignited combustion engine was n-butane basis LPG fuel, which is primarily used for taxi vehicles in Korea. The characteristics of nano-particle size distribution and number concentration of particle sizes ranging from 20 to 1,000 nm (aerodynamic diameter) that were emitted from the three LPG vehicles with various LPG supply systems were investigated by using a condensation particle counter (CPC), which is recommended by the PMP under both the NEDC and FTP-75 test modes on a chassis dynamometer. The experimental results indicate that the PN emission characteristics that were obtained by the CPC system using the PMP procedure are sufficiently reliable compared to other regulated emissions. Additionally, the sources of PN emissions in ascending order of magnitude are as follows: mixer type, gas-phase LPG injection (LPGi) and liquid-phase LPG injection (LPLi) passenger vehicles. The liquid-phase LPG injection system produced relatively large particle sizes and number concentrations compared to the gaseous system, regardless of the vehicle driving cycle. This phenomenon can be explained by unburned micro-fuel droplets that were generated due to a relatively short homogeneous fuel-air mixture duration in the engine intake manifold. Also the particle number emissions from the LPG vehicle were influenced by the vehicle driving cycle.  相似文献   
214.
In order to develop a fatigue design method for actual railroad car and commercial vehicle body structures using the fatigue data of simulated single spot-welded lap joints, we first analyzed the stress distribution and evaluated fatigue strength of spot-welded T-type members that are the components of actual railroad car and commercial vehicle body structures. Next, fatigue design approach of these members using the fatigue data of single spot-welded lap joints was investigated. From our results, we found that, even though there was a quantitative difference of fatigue strength between the single spot-welded joint and the actual members over the same number of fatigue cycles, through the use of appropriate correction, the fatigue design criterion of actual spot-welded members, such as those used in railroad car and commercial vehicle body, can be predicted using the fatigue strength of single spot-welded joint.  相似文献   
215.
Increasing fuel economy has been a central issue in the development of new cars, and one of the important strategies to improve fuel economy is to decrease vehicle weight. In order to obtain this goal, researchers have sought to make bumpers lighter without sacrificing strength, ability to absorb impact, or passenger safety. In this study, the effects of structural variables on the torsional stiffness of a body bumper impact beam were analyzed for possible weight reduction. To this end, the effects of variation of section height, increase of impact beam thickness and the addition of stays in a bumper impact beam were carefully investigated and compared. Among these, the most effective way to increase the torsional stiffness of the bumper impact beam was found to be increasing the section height. In addition, the potential for overall weight reduction of the impact beam was examined by comparing the crash capability of a bumper using conventional steels with that of high-strength steel (boron steel) with a tensile strength of 1.5 GPa. This analysis could serve as a guide to design for optimal bumper impact beam development.  相似文献   
216.
In this paper, a novel spacing control law is developed for vehicles with adaptive cruise control (ACC) systems to perform spacing control mode. Rather than establishing a steady-state following distance behind a newly encountered vehicle to avoid collision, the proposed spacing control law based on model predictive control (MPC) further considers fuel economy and ride comfort. Firstly, a hierarchical control architecture is utilized in which a lower controller compensates for nonlinear longitudinal vehicle dynamics and enables to track the desired acceleration. The upper controller based on the proposed spacing control law is designed to compute the desired acceleration to maintain the control objectives. Moreover, the control objectives are then formulated into the model predictive control problem using acceleration and jerk limits as constrains. Furthermore, due to the complex driving conditions during in the transitional state, the traditional model predictive control algorithm with constant weight matrix cannot meet the requirement of improvement in the fuel economy and ride comfort. Therefore, a real-time weight tuning strategy is proposed to solve time-varying multi-objective control problems, where the weight of each objective can be adjusted with respect to different operating conditions. In addition, simulation results demonstrate that the ACC system with the proposed real-time weighted MPC (RW-MPC) can provide better performance than that using constant weight MPC (CW-MPC) in terms of fuel economy and ride comfort.  相似文献   
217.
在泉州城周围的一些村子里,生活着由波斯人和阿拉伯人后裔组成的群体,他们相对集中在那里的13个村庄里,最著名的有晋江陈埭和惠安百奇.其中,丁、郭、二姓是他们中最为重要的宗族.  相似文献   
218.
This research aims to develop an actively translating rear diffuser device to reduce the aerodynamic drag experienced by passenger cars. One of the features of the device is that it is ordinarily hidden under the rear bumper but slips out backward only under high-speed driving conditions. In this study, a movable arc-shaped semi-diffuser device, round in form, is designed to maintain the streamlined automobile??s rear underbody configuration. The device is installed in the rear bumper section of a passenger car. Seven types of rear diffuser devices whose positions and protrusive lengths and widths are different (with the basic shape being identical) were installed, and Computational Fluid Dynamics (CFD) analyses were performed under moving ground and rotating wheel conditions. The main purpose of this study is to explain the aerodynamic drag reduction mechanism of a passenger car cruising at high speed via an actively translating rear diffuser device. The base pressure of the passenger car is increased by deploying the rear diffuser device, which then prevents the low-pressure air coming through the underbody from directly soaring up to the rear surface of the trunk. At the same time, the device generates a diffusing process that lowers the velocity but raises the pressure of the underbody flow, bringing about aerodynamic drag reduction. Finally, the automobile??s aerodynamic drag is reduced by an average of more than 4%, which helps to improve the constant speed fuel efficiency by approximately 2% at a range of driving speeds exceeding 70 km/h.  相似文献   
219.
A pseudo-two-dimensional numerical model of estuarine phytoplankton growth and consumption, vertical turbulent mixing, and idealized cross-estuary transport was developed and applied to South San Francisco Bay. This estuary has two bathymetrically distinct habitat types (deep channel, shallow shoal) and associated differences in local net rates of phytoplankton growth and consumption, as well as differences in the water column's tendency to stratify. Because many physical and biological time scales relevant to algal population dynamics decrease with decreasing depth, process rates can be especially fast in the shallow water. We used the model to explore the potential significance of hydrodynamic connectivity between a channel and shoal and whether lateral transport can allow physical or biological processes (e.g. stratification, benthic grazing, light attenuation) in one sub-region to control phytoplankton biomass and bloom development in the adjacent sub-region. Model results for South San Francisco Bay suggest that lateral transport from a productive shoal can result in phytoplankton biomass accumulation in an adjacent deep, unproductive channel. The model further suggests that turbidity and benthic grazing in the shoal can control the occurrence of a bloom system-wide; whereas, turbidity, benthic grazing, and vertical density stratification in the channel are likely to only control local bloom occurrence or modify system-wide bloom magnitude. Measurements from a related field program are generally consistent with model-derived conclusions.  相似文献   
220.
HE15 is a heat treatable high strength alloy with excellent machinability find wide applications in aerospace and defence industries. In view of their excellent mechanical properties, workability, machinability, heat treatment characteristics and good resistance to general and stress corrosion cracking, MDN138 & MDN250 have been widely used in petrochemical, nuclear and aerospace industries. The galvanic corrosion behaviour of the metal combinations HE15 /MDN138 and HE15 /MDN250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI’s Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN138, MDN250 and HE15 of the individual metal, the galvanic potential and galvanic current of the couples HE15 /MDN138 and HE15 /MDN250 were periodically monitored throughout the study period. The calcareous deposits on MDN138 and MDN250 in galvanic contact with HE15 were analyzed using XRD. The electrochemical behaviors of MDN138, MDN250 and HE15 in seawater have been studied using an electrochemical work station. The surface characteristics of MDN138 and MDN250 in galvanic contact with HE15 have been examined with scanning electron microscope. The results of the study reveal that HE15 offered required amount of protection to MDN138 & MDN250.  相似文献   
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