全文获取类型
收费全文 | 6903篇 |
免费 | 104篇 |
专业分类
公路运输 | 1838篇 |
综合类 | 1354篇 |
水路运输 | 2053篇 |
铁路运输 | 577篇 |
综合运输 | 1185篇 |
出版年
2023年 | 33篇 |
2022年 | 102篇 |
2021年 | 95篇 |
2020年 | 66篇 |
2019年 | 51篇 |
2018年 | 429篇 |
2017年 | 369篇 |
2016年 | 384篇 |
2015年 | 103篇 |
2014年 | 209篇 |
2013年 | 550篇 |
2012年 | 350篇 |
2011年 | 533篇 |
2010年 | 537篇 |
2009年 | 371篇 |
2008年 | 481篇 |
2007年 | 410篇 |
2006年 | 271篇 |
2005年 | 264篇 |
2004年 | 140篇 |
2003年 | 154篇 |
2002年 | 86篇 |
2001年 | 92篇 |
2000年 | 93篇 |
1999年 | 51篇 |
1998年 | 51篇 |
1997年 | 65篇 |
1996年 | 56篇 |
1995年 | 61篇 |
1994年 | 35篇 |
1993年 | 37篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 29篇 |
1989年 | 19篇 |
1988年 | 21篇 |
1987年 | 20篇 |
1986年 | 20篇 |
1985年 | 27篇 |
1984年 | 27篇 |
1983年 | 25篇 |
1982年 | 26篇 |
1981年 | 37篇 |
1980年 | 25篇 |
1979年 | 39篇 |
1978年 | 14篇 |
1977年 | 27篇 |
1976年 | 18篇 |
1975年 | 23篇 |
1974年 | 13篇 |
排序方式: 共有7007条查询结果,搜索用时 15 毫秒
11.
A paper was published in the immediately previous issue of this journal describing a stated preference experiment examining how people are influenced in the selection of a departure time for a hypothetical trip to see a movie. The title was ‘A stated preference examination of time of travel choice for a recreational trip’, Volume 30(3):17–44. Numbers were used to indicate references in the text of the paper and in Table 1 accompanying the text, but these numbers were omitted from the list of references at the end of the paper - making it very difficult to identify specific citations. The list of references from the paper is reprinted below with the reference numbers included. This provides a listing that can be used in conjunction with the text of the paper and Table 1 as published to identify specific citations as intended. 相似文献
12.
13.
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
14.
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
15.
宋庚水 《筑路机械与施工机械化》1997,14(1):39-41
从公路发展对养护工作的要求出发,对目前以小四轮牵引车为主要机型的养护机具进行了分析,探讨了开发新型道路养护车的必要性和开发原则,并对其可靠性进行了经济评价。 相似文献
16.
Benthic community patterns reflect water column processes in the Northeast Water polynya (Greenland)
Dieter Piepenburg William G. Ambrose Jr. Angelika Brandt Paul E. Renaud Michael J. Ahrens Preben Jensen 《Journal of Marine Systems》1997,10(1-4)
Benthic community patterns were investigated in the Northeast Water polynya (Greenland) during the summers of 1992 and 1993 to elucidate to what extent the bottom fauna is influenced by the dynamics of the overlying water. Five different fractions of the benthos (foraminiferans, nematodes, polychaetes, peracarid crustaceans, and epibenthic megafauna), ranging in average adult body size over 6 orders of magnitude (from about 100 μm to about 10 cm), were sampled quantitatively at 69 stations in water depths from 40 to 515 m. Total abundances of nematodes, polychaetes and peracarid crustaceans were found to be primarily correlated with parameters characterizing the potential benthic food supply (water column pigment and nitrate concentrations, sediment bound pigments and sediment biological activity), whereas abundances of foraminiferans and megabenthos were largely associated with seabed properties. Four benthic zones were distinguished by separately analyzing the faunistic composition and distribution of the five community fractions for Ob Bank, Western Westwind Trough, Eastern Westwind Trough, and Belgica Trough. This pattern was shown principally to reflect pelagic regimes differing in surface water hydrography, ice cover and euphotic productivity. This is the first time that a synoptic study of several benthic community portions spanning such a range in sizes and life styles has been performed in a polar shelf ecosystem. Our results indicate that abundances as well as composition of Arctic benthos are largely influenced by mesoscale pelagic processes, and thus provide further evidence for the importance of the benthic-pelagic coupling in high latitude seas. 相似文献
17.
本文根据21世纪初世界军事格局的变化特点,分析了美,俄海军装备发展趋势,并从六个引入关注的方面,论述了高新技术对军事装备发展的推动力。 相似文献
18.
对在大秦线路上运用C80车辆出现的踏面非正常磨耗情况进行调查、统计和分析,指出车轮材质耐磨性较差、结构设计不合理是其主要原因,有针对性地提出了改进建议。 相似文献
19.
Andrew J. Pick David J. Cole 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(9):781-805
The article reports an experimental study of driver steering control behaviour in a lane-change manoeuvre. Eight test subjects were instrumented with electromyography to measure muscle activation and co-contraction. Each subject completed 30 lane-change manoeuvres with one vehicle on a fixed-base driving simulator. For each driver, the steering torque feedback characteristic was changed after every ten manoeuvres; the response of the vehicle to steering angle inputs was not changed. Drivers' control strategies were found to be robust to changes in steering torque feedback. Path-following errors, muscle activity and muscle co-contraction all reduce with the number of lane-changes performed by the driver, suggesting the existence of a learning process. Comparing the test subjects, there was some evidence that high levels of co-contraction were used to allow high-frequency steering inputs to be generated. The results contribute to the understanding of vehicle-driver (and more generally, human-machine) dynamic interaction. 相似文献
20.
用未确知数学方法确定地基极限承载力 总被引:1,自引:0,他引:1
在介绍未确知信息理论的概念及其应用领域的基础上,对未确知信息数学处理方法和过程进行了简要说明。运用这一处理方法对西安某场地地基土的极限承载力取值进行了计算分析,结果表明这一方法在不确定性信息处理中比传统方法具有更多的优点,能够给出不同保证率下地基极限承载力,表明其处理数据更精细、更科学,值得在地质工程相关数据处理中进一步探讨和应用。 相似文献