全文获取类型
收费全文 | 3183篇 |
免费 | 8篇 |
专业分类
公路运输 | 847篇 |
综合类 | 719篇 |
水路运输 | 953篇 |
铁路运输 | 36篇 |
综合运输 | 636篇 |
出版年
2023年 | 10篇 |
2022年 | 21篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 368篇 |
2017年 | 325篇 |
2016年 | 362篇 |
2015年 | 10篇 |
2014年 | 37篇 |
2013年 | 140篇 |
2012年 | 126篇 |
2011年 | 344篇 |
2010年 | 334篇 |
2009年 | 100篇 |
2008年 | 281篇 |
2007年 | 149篇 |
2006年 | 14篇 |
2005年 | 69篇 |
2004年 | 60篇 |
2003年 | 60篇 |
2002年 | 30篇 |
2001年 | 8篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 25篇 |
1997年 | 14篇 |
1996年 | 20篇 |
1995年 | 18篇 |
1994年 | 6篇 |
1993年 | 11篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1977年 | 16篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 10篇 |
1973年 | 5篇 |
排序方式: 共有3191条查询结果,搜索用时 46 毫秒
951.
This paper addresses the issue of using before and after surveys to evaluate behavioural changes in response to transport
policies and investments, a procedure that, we argue is done far too rarely in this profession. Further, it demonstrates very
clearly that, in almost all conceivable cases, there are considerable economies to be obtained by using a panel (again, under-utilised
in our profession) to undertake evaluation, rather than successive independent cross-sectional surveys. The paper also addresses
the critical issue of sample size requirements for measuring changes of a relatively small magnitude in travel behaviour;
i.e., to state, with 95% confidence, that if there is a ∂ percent change in behaviour for the sample, there is a ∂ percent ± e
percent change in the behaviour of the population, where e is the sampling error. In this paper, we present a method for calculating such sample size requirements from first principles
and demonstrate the applicability both hypothetically and then empirically using data from the Puget Sound Transportation
Panel. The formulation enables designers of before and after surveys to investigate the trade-offs between the statistical
accuracy of their predictions and the sample size requirements systematically, without the need to specify ∂ a priori. This
latter point is crucial, we argue, because we have limited information on ∂, yet, as we explain here, it drives the sample
size requirements using alternative, well-cited approaches for calculating sample sizes to assess behavioural change. The
results have important ramifications both for those implementing transport policies intended to produce behavioural change,
especially when a cost-benefit evaluation of the policy is desired, and for those interpreting the results reported in previous
studies. 相似文献
952.
Influences on bicycle use 总被引:2,自引:0,他引:2
A stated preference experiment was performed in Edmonton in Canada to both examine the nature of various influences on bicycle
use and obtain ratios among parameter values to be used in the development of a larger simulation of household travel behaviour.
A total of 1128 questionnaires were completed and returned by current cyclists. Each questionnaire presented a pair of possible
bicycle use alternatives and asked which was preferred for travel to a hypothetical all-day meeting or gathering (business
or social). Alternatives were described by specifying the amounts of time spent on three different types of cycling facility
and whether or not showers and/or secure bicycle parking were available at the destination. Indications of socio-economic
character and levels of experience and comfort regarding cycling were also collected. The observations thus obtained were
used to estimate the parameter values for a range of different utility functions in logit models representing this choice
behaviour. The results indicate, among other things, that time spent cycling in mixed traffic is more onerous than time spent
cycling on bike lanes or bike paths; that secure parking is more important than showers at the destination; and that cycling
times on roadways tend to become less onerous as level of experience increases. Some of these results are novel and others
are consistent with findings regarding bicycle use in work done by others, which is seen to add credence to this work. A review
of previous findings concerning influences on cycling behaviour is also included. 相似文献
953.
Martin F. Diez-Picazo 《WMU Journal of Maritime Affairs》2007,6(2):241-247
A cross-cutting Maritime Policy can ensure that climate change threats and challenges in regards to seas and oceans are dealt
with in a wide policy framework that takes into account the impacts that climate change may have on other sectors and vice
versa. 相似文献
954.
Genetic algorithms (GAs) can powerfully search for parameters in a large multidimensional design space. Thus, the principle
can be applied to preliminary series propeller design problems with multiple considerations. In the present study, B-series
propeller design was conducted using a GA for both hydrodynamic efficiency and vibration consideration. The objective function
was set by users who could freely weight the relative importance of efficiency and vibration. GAs were successfully shown
to be able to obtain an optimal set of parameters leading to efficient performance and low vibration. 相似文献
955.
956.
D. Swaroop Assistant Professor R. Huandra Graduate Student 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1998,30(5):319-344
This paper investigates the problem of designing Intelligent Cruise Control (ICC) algorithms for partially and fully automated highways. ICC algorithms must guarantee that density disturbances attenuate as they propagate upstream. Such a desirable property of traffic is dependent on the spacing policy employed by automated vehicles and on the availability of information required to synthesize a string stable control law consistent with the employed spacing policy. The first part of the paper is concerned with the design of the spacing policy and the latter part is concerned with synthesizing ICC algorithms. Various other issues relating to the design of ICC are also discussed. 相似文献
957.
958.
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
959.
D. A. Crolla 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1980,9(5):237-260
A six degree of freedom model of an agricultural tractor and trailer combination has been developed. Results from eigenvalue and frequency response calculations indicated that tractor operator vibration levels will be higher when operating with a trailer than for the tractor alone, due mainly to increased tractor pitch motion.
Although minor improvements could be made to present tractor and trailer combinations by moving the hitch forward of the tractor rear axle or providing some damping at a sprung hitch, the scope for a significant improvement in ride lies in changing the configuration. If higher speed specialised transport vehicles prove economical for agriculture, there are some advantages in ride vibration to be gained by changing the layout of the tractor and trailer combination to resemble an off-road version of a commercial articulated lorry. 相似文献
Although minor improvements could be made to present tractor and trailer combinations by moving the hitch forward of the tractor rear axle or providing some damping at a sprung hitch, the scope for a significant improvement in ride lies in changing the configuration. If higher speed specialised transport vehicles prove economical for agriculture, there are some advantages in ride vibration to be gained by changing the layout of the tractor and trailer combination to resemble an off-road version of a commercial articulated lorry. 相似文献
960.