全文获取类型
| 收费全文 | 1147篇 |
| 免费 | 5篇 |
专业分类
| 公路运输 | 507篇 |
| 综合类 | 41篇 |
| 水路运输 | 265篇 |
| 铁路运输 | 42篇 |
| 综合运输 | 297篇 |
出版年
| 2023年 | 14篇 |
| 2022年 | 37篇 |
| 2021年 | 13篇 |
| 2020年 | 7篇 |
| 2019年 | 9篇 |
| 2018年 | 26篇 |
| 2017年 | 26篇 |
| 2016年 | 57篇 |
| 2015年 | 15篇 |
| 2014年 | 69篇 |
| 2013年 | 138篇 |
| 2012年 | 74篇 |
| 2011年 | 69篇 |
| 2010年 | 62篇 |
| 2009年 | 77篇 |
| 2008年 | 50篇 |
| 2007年 | 18篇 |
| 2006年 | 20篇 |
| 2005年 | 28篇 |
| 2004年 | 18篇 |
| 2003年 | 19篇 |
| 2002年 | 21篇 |
| 2001年 | 18篇 |
| 2000年 | 17篇 |
| 1999年 | 17篇 |
| 1998年 | 11篇 |
| 1997年 | 14篇 |
| 1996年 | 13篇 |
| 1995年 | 20篇 |
| 1994年 | 11篇 |
| 1993年 | 13篇 |
| 1992年 | 6篇 |
| 1991年 | 7篇 |
| 1989年 | 4篇 |
| 1988年 | 4篇 |
| 1987年 | 7篇 |
| 1986年 | 8篇 |
| 1985年 | 8篇 |
| 1984年 | 9篇 |
| 1983年 | 12篇 |
| 1982年 | 6篇 |
| 1981年 | 11篇 |
| 1980年 | 9篇 |
| 1979年 | 9篇 |
| 1977年 | 10篇 |
| 1976年 | 10篇 |
| 1975年 | 15篇 |
| 1974年 | 5篇 |
| 1973年 | 3篇 |
| 1972年 | 3篇 |
排序方式： 共有1152条查询结果，搜索用时 15 毫秒
881.
H. Imine Y. Delanne N. K. M'Sirdi 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(4):285-303
Vehicle motion simulation accuracy, such as in accident reconstruction or vehicle controllability analysis on real roads, can be obtained only if valid road profile and tire-road friction models are available. Regarding road profiles, a new method based on sliding mode observers has been developed and is compared with two inertial methods. Experimental results are shown and discussed to evaluate the robustness of our approach. 相似文献
882.
Y. S. Pyoun H. T. Kim Y. C. Lee A. Gafurov H. Kim D. H. Jung 《International Journal of Automotive Technology》2008,9(1):61-70
Surface topology, cone angle and the forces acting on the cone of the clutch type limited slip differential (LSD) are major design parameters for the bias ratio and the noise condition. Therefore much research has been dedicated to these developments but the results have been used to submit patents. A new cone type limited slip differential for sport utility vehicles and recreational vehicles, which has a very simple structure and easy compliance with the vehicle performance, has been developed by the axiomatic approach and the ultrasonic nano crystal surface modification (UNSM) technology. The design criteria and optimal value of the design parameters are determined by the axiomatic approach utilizing CAE tools. Test methodologies in a test rig and in a vehicle were also developed. Test results showed good performance of bias ratio and noise level but durability is still under testing. This study is an extension of F2006P266, FISITA 2006. 相似文献
883.
T. H. Hwang K. Park S. -J. Heo S. H. Lee J. C. Lee 《International Journal of Automotive Technology》2008,9(1):17-27
The performance of most electronic chassis control systems in the past has been optimized individually. Recently, a great research effort has been dedicated to the integration of chassis control systems in an effort to improve the vehicle performance. This involves orchestration of individual control modules so that they can jointly contribute to the enhancement of their control effect. In this research, two integrated control logics for AFS (Active Front Steering) and ESP (Electronic Stability Program) have been developed. Of the two logics, one uses a supervisor that rules over the individual modules. The other logic uses a CL (Characteristic Locus) method, which is a frequency-domain multivariable control technique. The two logics have been tested under various driving conditions to investigate their control effects. The results indicate that the proposed integrated control logics can yield vehicle performance that is superior to that of the individual control modules without any integration scheme. 相似文献
884.
Mark E. Baird Patrick G. Timko Iain M. Suthers Jason H. Middleton 《Journal of Marine Systems》2006,59(3-4):249-270
885.
Y. Tsutsumi A. Iijima K. Yoshida H. Shoji J. T. Lee 《International Journal of Automotive Technology》2009,10(6):645-652
The Homogeneous Charge Compression Ignition (HCCI) engine has attracted much interest because it can simultaneously achieve high efficiency and low emissions. However, the ignition timing is difficult to control because this engine has no physical ignition mechanism. In addition, combustion proceeds very rapidly because the premixed mixture ignites simultaneously at multiple locations in the cylinder, making it difficult to increase the operating load. In this study, an HCCI engine was operated using blended test fuels comprised of dimethyl ether (DME) and methane, each of which have different ignition characteristics. The effects of mixing ratios and absolute quantities of the two types of fuel on the ignition timing and rapidity of combustion were investigated. Cool flame reaction behavior, which significantly influences the ignition, was also analyzed in detail on the basis of in-cylinder spectroscopic measurements. The experimental results revealed that within the range of the experimental conditions used in this study, the quantity of DME supplied substantially influenced the ignition timing, whereas there was little observed effect from the quantity of methane supplied. Spectroscopic measurements of the behavior of a substance corresponding to HCHO also indicated that the quantity of DME supplied significantly influenced the cool flame behavior. However, the rapidity of combustion could not be controlled even by varying the mixing ratios of DME and methane. It was made clear that changes in the ignition timing substantially influence the rapidity of combustion. 相似文献
886.
J. Kim N. Kim S. Hwang Y. Hori H. Kim 《International Journal of Automotive Technology》2009,10(6):733-742
A motor control strategy for an input-split hybrid electric vehicle (HEV) is proposed. From a power characteristic analysis, it is found that the powertrain efficiency decreases for speed ratios at which power circulation occurs. Using dynamic models of an input-split HEV powertrain, a motor-generator control algorithm for obtaining high system efficiency is designed by inversion-based control. The performance of the control algorithm is evaluated by the simulator which is developed based on PSAT, and simulation results are compared with the test results. It is found that, even if the engine thermal efficiency is sacrificed by moving the engine operation point from the OOL for the control strategy, improved overall powertrain system efficiency can be achieved by the engine operation that gives a relatively high efficiency from the viewpoint of the overall powertrain efficiency. The control algorithm developed can be used in design of future electric vehicles. 相似文献
887.
大众汽车公司的机械式G型增压器 总被引：1，自引：0，他引：1
本文介绍了德国大众汽车公司设计、生产的采用螺旋推进压气原理的工作的Ｇ型增压器,对其原理、结果及应用作了详细的分析说明。 相似文献
888.
H. Yamaguchi S.-I. Doi N. Iwama Y. Hayashi 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1993,22(5):299-308
The improvements of ride comfort and vehicle maneuverability in the vehicle design can be achieved by using an active suspension. However, the problems in such a control are the complex control logic because of the control laws incompatible with the improvements of ride comfort and maneuverability, and the cost increase because of various sensors to be attached. Therefore, we examined the control abilities of ride comfort and maneuverability on a unique control law using frequency shaped LQ, and controlled the characteristic of the contact between tire and road without a road displacement sensor 相似文献
889.
The demand for inland freight transport in Europe is mainly met by road transport, leading to unsustainable impacts such as air pollution, greenhouse gas emissions and congestion. Since rail transport has lower externalities than road transport, a modal shift from road to rail is an accepted policy goal for achieving a more sustainable and competitive transport system. However, intermodal road–rail transport is mainly competitive for long-distance transport, and as a consequence, the potential for modal shift is limited. The cost efficiency of road–rail intermodal transport is particularly sensitive to pre- and post-haulage (PPH) costs, since this activity typically has a larger cost compared with its share of the total distance in the transport chain. For intermodal transportation over shorter distances, for example, below 300 km and where there are substantial PPH activities at both ends of the chain, the competitiveness of the intermodal transport system compared with that of direct road is low. Improving the efficiency of PPH activities is, therefore, of utmost importance for the competitiveness of the intermodal transport system. This paper looks into the issue of improving the cost efficiency of an intermodal transport chain by implementing an innovative and flexible legal framework regarding the PPH activities in the chain. By extending the legal framework with exemptions for longer vehicles in PPH, the cost efficiency could be greatly improved. The purpose of such a framework is to allow and enable, for PPH exclusively, the use of 2?×?40 foot or even two semi-trailers using only one vehicle in the context of the Swedish regulatory framework. This paper develops a strategic calculation model for assessing and investigating the consequences of such a framework and investigates the framework's potential in terms of cost efficiency. The model in combination with a sensitivity analysis of input variables gives a comprehensive understanding of the effects of PPH under different circumstances. From the results, it is evident that there are substantial positive effects associated with a PPH framework of longer vehicles. Results indicate that a typical shipper may experience cost reductions of about 5–10% of the total costs of the intermodal transport chain. In summary, a more innovative and flexible legal framework regarding vehicle length in the PPH links can contribute to a greater modal shift, improved cost efficiency and more environmentally friendly transportation systems. 相似文献
890.
Interest in alternative behavioural paradigms to random utility maximization (RUM) has existed ever since the dominance of the RUM formulation. One alternative is known as random regret minimization (RRM), which suggests that when choosing between alternatives, decision makers aim to minimize anticipated regret. Although the idea of regret is not new, its incorporation into the same discrete choice framework of RUM is very recent. This paper is the first to apply the RRM‐model framework to model choice amongst durable goods. Specifically, we estimate and compare the RRM and RUM models in a stated choice context of choosing amongst vehicles fuelled with petrol, diesel and hybrid (associated with specific levels of fuel efficiency and engine capacity). The RRM model is found to achieve a marginally better fit (using a non‐nested test of differences) than its equally parsimonious RUM counterpart. As a second contribution, we derive a formulation for regret‐based elasticities and compare utility‐based and regret‐based elasticities in the context of stated vehicle type choices. We find that in the context of our choice data, mean estimates of elasticities are different for many of the attributes and alternatives. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献