全文获取类型
收费全文 | 24181篇 |
免费 | 331篇 |
专业分类
公路运输 | 6160篇 |
综合类 | 4904篇 |
水路运输 | 6523篇 |
铁路运输 | 4079篇 |
综合运输 | 2846篇 |
出版年
2023年 | 56篇 |
2022年 | 334篇 |
2021年 | 475篇 |
2020年 | 387篇 |
2019年 | 171篇 |
2018年 | 320篇 |
2017年 | 229篇 |
2016年 | 320篇 |
2015年 | 496篇 |
2014年 | 862篇 |
2013年 | 2007篇 |
2012年 | 1284篇 |
2011年 | 1579篇 |
2010年 | 1509篇 |
2009年 | 1797篇 |
2008年 | 1698篇 |
2007年 | 2022篇 |
2006年 | 1923篇 |
2005年 | 1357篇 |
2004年 | 620篇 |
2003年 | 462篇 |
2002年 | 367篇 |
2001年 | 449篇 |
2000年 | 461篇 |
1999年 | 292篇 |
1998年 | 268篇 |
1997年 | 212篇 |
1996年 | 274篇 |
1995年 | 216篇 |
1994年 | 157篇 |
1993年 | 242篇 |
1992年 | 192篇 |
1991年 | 118篇 |
1990年 | 113篇 |
1989年 | 81篇 |
1988年 | 93篇 |
1987年 | 71篇 |
1986年 | 71篇 |
1985年 | 81篇 |
1984年 | 81篇 |
1983年 | 73篇 |
1982年 | 73篇 |
1981年 | 95篇 |
1980年 | 68篇 |
1979年 | 91篇 |
1978年 | 56篇 |
1977年 | 69篇 |
1976年 | 53篇 |
1975年 | 65篇 |
1974年 | 50篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
作者介绍了乘务员公寓管理软件设计中用链表组成的的数据结构,用C/C 语言组成动态存储链表的程序设计方法,并结合乘务员公寓管理软件设计,阐述了链表的定义、存储结构及相应的各种操作。 相似文献
53.
David A. Hensher 《Transportation Research Part A: Policy and Practice》1997,31(6):431-446
This paper presents the methodology and selective empirical results from a study of the demand for a high speed rail system serving the Sydney-Canberra corridor currently dominated by air travel for business trips and car travel for non-business trips. We outline the steps involved in the study from problem specification, data needs, development of base year trip tables, model specification and estimation to establish switching behaviour in the presence of a new mode and calculation of induced demand for current travellers. A stated choice heteroskedastic extreme value switching model is used to evaluate the choice of fare type for business and non-business travel given the current mode used in the corridor for each sampled traveller conventional train, charter coach, scheduled coach, plane or car. Starting with the current travel profile, patronage can be predicted under alternative fare regimes, taking into account diverted traffic, induced traffic and growth. Treating fare class as endogenous enhances the real choice context facing potential patrons. 相似文献
54.
Despite improvements in road safety over the past several decades, accident rates remain high for young drivers. One accident countermeasure that is expected to improve the safety record of this group is graduated licensing. The philosophy behind this licensing system is that novice drivers, of whom the majority are young, should be restricted to relatively safe driving environments during the initial learning period. Graduated licensing was implemented in the Province of Ontario, Canada in 1994. The objective of this study is to estimate the potential benefits and costs for young drivers associated with two components of the Ontario graduated licensing package: the late-night driving curfew and the high-speed roadway restrictions. Based on accident and travel data for the year 1988, accident-involvement rates per kilometre driven were calculated for different driver groups for various combinations of time of day and roadway speed limit. These rates were then applied to the expected mobility profiles of young drivers affected by graduated licensing. The results of the study support the late-night curfew and suggest that this component of the licensing package should reduce total accident involvements for the affected group by up to 10 percent and fatal accident involvements by up to 24 percent, while reducing their total driving by only four percent. By contrast, the empirical evidence suggest that the high-speed roadway restrictions are likely to increase accident involvements, and thus it is strongly recommended that this component of Ontario's graduated licensing package be changed. 相似文献
55.
This paper presents a transit assignment algorithm for crowded networks. Both congestion in vehicles and queuing at stations are explicitly taken into account in predicting passenger flows for a fixed pattern of origin-destination trip demands. The overflow effects due to insufficient capacity of transit lines are considered to be concentrated at transit stations, while the in-vehicle congestion effects (or discomforts) are considered to be dependent on in-vehicle passenger volume. Overflow delay at a transit station is dependent on the number of excess passengers required to wait for the next transit car. We use a logit model to determine the split between passengers that chose to wait for the next transit car and passengers that chose to board on the alternative transit lines. The proposed algorithm predicts how passenger will choose their optimal routes under both queuing and crowded conditions. 相似文献
56.
介绍了SS7c型客运电力机车的主要设计思路、特性、技术参数等,对其牵引客运列车的性能进行了简要的分析。 相似文献
57.
舰船模块化设计中信息集成化的数据信息模型研究 总被引:2,自引:0,他引:2
介绍了产品集成信息模型的基本框架和用STEP标准建立构件模型和装配模型的方法,并以球面隔壁为对象给出构件模型和装配模型的实例。 相似文献
58.
Theo E. Notteboom 《Maritime Policy and Management》2002,29(3):257-269
The first part of this paper brings into discussion some recent changes in the dynamics of the European container handling business, in particular as a result of vertical and horizontal integration strategies of container terminal operators. The industry structure has become sufficiently consolidated to raise a fundamental question about whether market forces are sufficient to prevent the abuse of market power. In this context, reference is made to the theory of contestable markets. The second part of the paper looks more closely to the issue of contestability by means of an exploratory and qualitative study of elements that could prevent other players entering or exiting the European container handling market. As such, a first indication is given of the degree of contestability in the container handling industry. 相似文献
59.
Dynamics of Tracked Vehicles 总被引:2,自引:0,他引:2
J.Y. Wong Professor 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1997,28(2):197-219
This paper provides a brief review of the state-of-the-art of tracked vehicle dynamics, including mobility over soft terrain, ride dynamics over rough surfaces and manoeuvrability. It is found that considerable progress has been made in the development of analytical frameworks for evaluating and predicting tracked vehicle mobility over soft terrain, taking into account the characteristics of terrain response to normal and shear loading. Certain computer simulation models for tracked vehicle mobility have been gaining increasingly wide acceptance by industry and governmental agencies in product development and in procurement. It is also found that most of the research on tracked vehicle ride dynamics and manoeuvrability is confined to operations on rigid surfaces. To achieve a realistic evaluation and prediction of the dynamic behaviour of tracked vehicles in the field, the key is to have a better understanding of terrain response to dynamic vehicular loading, including its dynamic stiffness and damping. Challenges that face vehicle dynamicists in this emerging field are identified. 相似文献
60.
D. W. Shuttlewood D. A. Crolla R. S. Sharp I. L. Crawford 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1993,22(5):383-396
The development of a mathematical model of a limited bandwidth hydro-pneumatic suspension that is incorporated into a vehicle handling model is described. The combined model is used to evaluate a suitable control strategy for eliminating body roll during a cornering manoeuvre. The philosophy behind the roll control strategy has been to use feedback measurements of the body motions which do not compromise the ride control. A study of the influence of the position of the body motion feedback transducer on the effectiveness of the system to reduce the body roll is presented. Non-linear modelling of the suspension components for a 0.8g cornering manoeuvre has revealed performance limitations. Conclusions are drawn as to the effectiveness of the control scheme. 相似文献