全文获取类型
收费全文 | 1322篇 |
免费 | 4篇 |
专业分类
公路运输 | 346篇 |
综合类 | 36篇 |
水路运输 | 457篇 |
铁路运输 | 39篇 |
综合运输 | 448篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 27篇 |
2017年 | 26篇 |
2016年 | 44篇 |
2015年 | 16篇 |
2014年 | 26篇 |
2013年 | 215篇 |
2012年 | 63篇 |
2011年 | 66篇 |
2010年 | 54篇 |
2009年 | 55篇 |
2008年 | 65篇 |
2007年 | 47篇 |
2006年 | 27篇 |
2005年 | 29篇 |
2004年 | 24篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 29篇 |
2000年 | 19篇 |
1999年 | 22篇 |
1998年 | 41篇 |
1997年 | 18篇 |
1996年 | 22篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 18篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1979年 | 16篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 17篇 |
1974年 | 10篇 |
1973年 | 9篇 |
排序方式: 共有1326条查询结果,搜索用时 359 毫秒
401.
Victor F. Ushkalov Michael M. Zhechev A. D. McKisic 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(1):61-76
Three-piece trucks have some drawbacks, particularly unstable operation of the friction wedge damping system. One of the principal features of systems of this kind is the possibility of jamming and wedging. This work is devoted to mathematical and numerical modeling of the plane motion of a freight car with allowance for the mobility of the wedges and then for the compliance of the contacting bodies and to the study of the conditions for the onset of jamming and wedging when the car is in motion. 相似文献
402.
Marshall Lindsey Joseph L. Schofer Pablo Durango-Cohen Kimberly A. Gray 《Transportation Research Part A: Policy and Practice》2010,44(9):697-709
The use of privately owned vehicles (POVs) contributes significantly to US energy consumption (EC) and greenhouse gas emissions (GHGe). Strategies for reducing POV use include shifting trips to other modes, particularly public transit. Choices to use transit are based on characteristics of travelers, their trips, and the quality of competing transportation services. Here we focus on the proximity of rail stations to trip origins/destinations as a factor affecting mode choice for work trips. Using household travel survey data from Chicago, we evaluate the profile of journey-to-work (JTW) trips, assessing mode share and potential for more travelers to use rail. For work trips having the origin/destination as close as 1 mile from rail transit stations, POVs were still the dominant travel mode, capturing as much as 61%, followed by rail use at 14%. This high degree of POV use coupled with the proportion of JTW trips within close proximity to rail stations indicated that at least some of these trips may be candidates for shifting from POV to rail. For example, shifting all work trips with both the origin/destination within 1 mile of commuter rail stations would potentially reduce the energy associated with all work-related POV driving trips by a maximum of 24%. Based on the analysis of trips having the origin and destination closest to train stations, a complete shift in mode from POV to train could exceed CO2 reduction goals targeted in the Chicago Climate Action Plan. This could occur with current settlement patterns and the use of existing infrastructure. However, changes in traveler behavior and possibly rail operation would be necessary, making policy to motivate this change essential. 相似文献
403.
Lorenzo Masiero David A. Hensher 《Transportation Research Part A: Policy and Practice》2010,44(5):349-358
Choice behaviour might be determined by asymmetric preferences whether the consumers are faced with gains or losses. This paper investigates loss aversion and diminishing sensitivity, and analyzes their implications on willingness to pay and willingness to accept measures in a reference pivoted choice experiment in a freight transport framework. The results suggest a significant model fit improvement when preferences are treated as asymmetric, proving both loss aversion and diminishing sensitivity. The implications on willingness to pay and willingness to accept indicators are particular relevant showing a remarkable difference between symmetric and asymmetric model specifications. Not accounting for loss aversion and diminishing sensitivity, when present, produces misleading results and might affect significantly the policy decisions. 相似文献
404.
ABSTRACTRidesourcing services such as Uber are nowadays a common feature within available transport options of many cities around the world (E.g. London & San Francisco). There has been much publicity about the potential impacts of ridesourcing services and how (or if) they should be managed or regulated without an objective understanding of who uses these services and why, as well as its current and future implications for public transport (PT).Ridesourcing is part of a broader tech-driven, mobile app-based sharing phenomenon – the ‘sharing economy’ – which has disrupted traditional market models and industries, for example, the transport industry, where new players such as Uber have emerged and have quickly become part of the urban transport landscape. Uber has been at the forefront in disrupting the transport sector since its first launch in 2010 (San Francisco, USA). Since its launch, Uber has generated extensive media coverage and debate among policymakers, transport planners and transport authorities on how these services are affecting traditional transport modes such as buses and taxis. However, without objective empirical data – in terms of impacts on trip making characteristics, PT ridership and congestion – policymakers and transport regulators are yet to fully understand the real impacts ridesourcing services are having on the transport network.This paper is part of broader research that aims to provide insights and empirical-based evidence on how Uber services are used (UberX and Uberpool) in London. A comprehensive survey was undertaken using a detailed questionnaire, issued to UberX and Uberpool users in London to gather detailed data on who uses the Uber services, why they use it and what are the trip purposes, in order to understand Uber user demographics and what effects (if any) Uber services are having on PT usage and trip making characteristics in London. The final findings provide important insights on Uber user demographics, trip purposes, types of trips replaced, impact on car ownership and why travellers use Uber services. 相似文献
405.
It is well known that the general circulation on the Catalan continental slope is dominated by a quasi-permanent southwestward geostrophic jet associated to the so-called Catalan front [Millot, C., 1987. Circulation in the western Mediterranean sea. Oceanol Acta 10, 143–149; Font, J., Salat, J., Tintoré, J., 1988. Permanent features of the circulation in the Catalan Sea. Oceanol. Acta 9, 51–57]. On the continental shelf, however, the flow is modified by the action of friction which enhances also other nonlinear interactions. Several authors have hypothesized that the shelf circulation is anticyclonic north of the Ebro delta [Salat, J., Manriquez, M., Cruzado, A., 1978. Hidrografia del golfo de Sant Jordi. Campaña Delta (Abril 1970). Investigación Pesquera 42 (2), 255–272; Ballester, A., Castellví, J., 1980. Estudio hidrográfico y biológico de las plataformas continentales españolas: I. Efecto de los efluentes de una planta de energía nuclear en el Golfo de San Jorge (Febrero 1975–Octubre 1976). Informes Técnicos del Instituto de Investigaciones Pesqueras 76, 70 pp.]. A quasi-3D finite element code based on the shallow-water equations has been used to explore the effect of several mechanisms which might be responsible for such a local circulation pattern, and in particular of wind. The obtained numerical results suggest that the basic anticyclonic structure of the mean flow is controlled by the bathymetry and that the clockwise-rotating mean flow pattern is not a permanent circulation feature. It is seen that the characteristic local wind stress fields—computed through interpolation of the records of a local network of meteo stations—may ‘enhance' or ‘delete' the anticyclonic gyre depending on the sign of their relative vorticity. According to the analysis of a 2-yr record of local wind data, the net contribution of wind events with a duration longer than 24 h is to reinforce the anticyclonic circulation (over 70% of these wind fields supply negative relative vorticity to the study area). 相似文献
406.
David A. Hensher 《Transportation Research Part B: Methodological》1985,19(4):303-313
Vehicle-use modelling at the household level has taken on new importance with the pressures on governments to encourage more efficient utilisation of increasingly scarce nonreplenishible liquid fuels. The fundamental energy equation recognizes two direct influences on consumption—the fuel efficiency of the vehicle and the amount of use. Until recently, the interrelationship between vehicle choice and vehicle utilisation at the household level was acknowledged but ignored. The availability of reliable vehicle-use data at the household level now enables a more serious effort at amending the imbalance of research effort where the reliance has been predominantly on vehicle choice modelling and gross (exogenous) assumptions on utilisation as a basis for predicting fuel consumption. This paper proposes an econometric method for identifying the influences on household vehicle use. It differs from previous empirical work in that vehicle kilometers, fuel cost per kilometer and vehicle fuel efficiency are endogenous, with utilisation of each vehicle endogeneously dependent on the utilisation of each and every household vehicle. The data are drawn from wave 1 of a four-wave panel of 1436 households in the Sydney metropolitan area. The empirical findings expose a set of influences on use hitherto not considered. The model specification provides an appropriate module for integration with household-based discrete choice models of vehicle choice. 相似文献
407.
408.
During a repeat grid survey and drogue study carried out in austral summer 1994/95, the abundance and feeding activity of salps were estimated in the Lazarev Sea region from net tows and in situ measurements of gut fluorescence. Throughout the survey area, Salpa thompsoni accounted for >95% of the total salp stock while Ihlea racovitzai was consistently represented in very low abundances. Maximum densities of S. thompsoni, with ≈4000 ind. 1000 m−3, were recorded in the Marginal Ice Zone (MIZ) in December when chlorophyll-a concentrations were well below 1 mg m−3. A dramatic decrease in salp stock was observed at the beginning of January, when S. thompsoni virtually disappeared from the most productive area of the MIZ where chlorophyll-a concentrations had by then reached bloom levels of 1.5–3 mg (Chl-a) m−3. In situ grazing measurements showed that throughout the cruise S. thompsoni exhibited the highest ingestion rates per individual of any of the most abundant components of the grazing pelagic community, with maxima of ≈160 μg (pigm) ind. −1 d−1. These feeding rates are 3 to 5 times higher than those previously obtained using in vitro incubations. The total daily consumption of the population of S. thompsoni varied from 0.3 to 108% of daily primary production. We suggest that competitive removal of food by S. thompsoni, rather than direct predation, is responsible for the low krill abundances generally associated with salp swarms. 相似文献
409.
A. D. May 《Transportation》1992,19(4):313-333
This paper reviews experience with road pricing in Europe and Asia. It considers the objectives of road pricing, and demonstrates that differences in objectives lead to differences in scheme design and performance. It reviews the criteria for design of road pricing systems, and the development of charging structures and technologies to meet those criteria. In particular it discusses the relative merits of pre-determined and congestion-dependent charging structures, and of off-vehicle and on-vehicle charging systems. It assesses the performance of road pricing systems to date, discusses objections to road pricing and demonstrates that the role of road pricing within a wider transport strategy and the use made of the revenue generated, will be important determinants of public acceptability. Finally it assesses the relative merits of alternative approaches to implementation and argues that these will need to pay as much regard to public acceptability as to technical performance. 相似文献
410.
Nils A. Bruzelius 《Transportation》1981,10(3):233-245
In a number of articles in this journal the use of generalised cost in travel demand analysis and transport planning has been subject to debate. However, some of the fundamental problems raised in these articles are left unanswered — e.g., the precise relationship between conventional microeconomic consumer demand theory and generalised cost, an issue with which this article is concerned. It is shown here that necessary and sufficient conditions for expressing travel demand in terms of generalised cost are that this cost, when measured in monetary units, is linear, and that the time variable is weighted by a constant marginal value of time. It is also shown that these conditions imply strong assumptions about the consumer's behaviour — e.g., that the willingness to pay to save time whilst travelling is not a function of real income. 相似文献