全文获取类型
收费全文 | 712篇 |
免费 | 5篇 |
专业分类
公路运输 | 166篇 |
综合类 | 61篇 |
水路运输 | 255篇 |
铁路运输 | 38篇 |
综合运输 | 197篇 |
出版年
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 12篇 |
2016年 | 22篇 |
2015年 | 11篇 |
2014年 | 19篇 |
2013年 | 108篇 |
2012年 | 27篇 |
2011年 | 31篇 |
2010年 | 31篇 |
2009年 | 39篇 |
2008年 | 38篇 |
2007年 | 25篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 15篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 19篇 |
1997年 | 18篇 |
1996年 | 13篇 |
1995年 | 21篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有717条查询结果,搜索用时 15 毫秒
281.
The newly-built tunnel passing closely under the existing station will inevitably lead to settlement of the existing station, and especially deformation joints are prone to differential settlement. Based on the Suzhoujie Station of Beijing Subway Line 16 passing closely under the existing Line 10, this paper analyzes the overall settlement of the existing station and the differential settlement at deformation joints through a combination of field measurement and numerical simulation. The study results show that installing jacks significantly prevents the settlement of the existing station, after installation of jacks the settlement of the existing station is reduced by about 58%, and the jacking force of the jack shall be controlled between 180-450 t; the impact of construction on the single-deck station structure side at deformation joints is greater than that on the double-deck station structure side, the stress on the socket is gradually increased with the excavation of the lower tunnel, and reduced after installation of jacks, indicating that the jack can effectively reduce the tensile stress of the existing station and maintain the safety of the existing station; with the action of the jacking force of jacks, the settlement curve of the existing station presents a stepwise change at the jack installation points, while the upper ground surface settlement is relatively uniform. © 2022, Editorial Office of Modern Tunnelling Technology. All right reserved. 相似文献
282.
Transportation - Weather events often force motorists to drive in unsafe conditions or alter travel plans. Both decisions are imbued with costs that drivers may minimize by developing adaptation... 相似文献
283.
Patel Hersila H. Messiah Sarah E. Hansen Eric D’Agostino Emily M. 《Transportation》2021,48(5):2315-2333
Transportation - Transportation vulnerability, defined as lack of access to transportation resulting in financial, social, or health consequences, reduces quality of life. While research has... 相似文献
284.
K. B. Artana T. Pitana D. P. Dinariyana M. Ariana D. Kristianto E. Pratiwi 《船舶与海洋工程学报》2018,17(1):101-111
The aim of this research is to develop an algorithm and application that can perform real-time monitoring of the safety operation of offshore platforms and subsea gas pipelines as well as determine the need for ship inspection using data obtained from automatic identification system (AIS). The research also focuses on the integration of shipping database, AIS data, and others to develop a prototype for designing a real-time monitoring system of offshore platforms and pipelines. A simple concept is used in the development of this prototype, which is achieved by using an overlaying map that outlines the coordinates of the offshore platform and subsea gas pipeline with the ship’s coordinates (longitude/latitude) as detected by AIS. Using such information, we can then build an early warning system (EWS) relayed through short message service (SMS), email, or other means when the ship enters the restricted and exclusion zone of platforms and pipelines. The ship inspection system is developed by combining several attributes. Then, decision analysis software is employed to prioritize the vessel’s four attributes, including ship age, ship type, classification, and flag state. Results show that the EWS can increase the safety level of offshore platforms and pipelines, as well as the efficient use of patrol boats in monitoring the safety of the facilities. Meanwhile, ship inspection enables the port to prioritize the ship to be inspected in accordance with the priority ranking inspection score. 相似文献
285.
Vertical flux of particulate material was recorded with moored sediment traps during 1988/1989 in the Greenland Sea at 72°N, 10°W. This region exhibits pronounced seasonal variability in ice cover. Annual fluxes at 500 m water depth were 22. 79, 8.55, 2.39, 3.81 and 0.51 g m−2 for total flux (dry weight), carbonate particulate biogenic silicate, particulate organic carbon and nitrogen, respectively. Fluxes increased in April, maximum rates of all compounds occurred in May–June, and consistently high total flux rates of around 100 mg m−2d−1 prevailed the summer. The increasing flux of biogenic particles measured in April is indicative of an early onset of algal growth in spring. Small pennate diatoms dominated in the trap collections during April, and were still numerous during the high flux period when Thalassiosira species were the most abundant diatoms. During May–June, up to 22% of the Thalassiosira cells collected were viable-looking cells. The faecal pellet flux increased after the May–June event. Therefore we conclude that the diatoms settled as phytodetritus, most likely in rapidly sinking aggregates. From seasonal nutrient profiles it is concluded that diatoms contribute 25% to new production during spring and 50% on an annual basis. More than 50% of newly produced silicate particles are dissolved above the 500 m horizon. High new production during spring does not lead to a pronounced sedimentation pulse of organic matter during spring but elevated vertical export is observed during the entire growth period. 相似文献
286.
铸造高冲击强度的球铁时,获得持续稳定的结果是非常重要的,尤其是考虑到确保零件在使用末期的使用性能时.例如:在汽车业,必须保证所提供的铸造零件能经得起实际工况,例如寒冷的天气下在坑洼地带其连续冲击的性能.铸造厂最根本的问题是辨别哪里可能存在潜在的断裂源并在铸件"上路"前消除它们. 相似文献
287.
石冰 《西安交通大学学报(英文版)》1995,(2)
DYNAMICCHANGESINGiα2LEVELSINTHERATHEARTASSOCIATEDWITHIMPAIREDCARDIACFUNCTIONFOLLOWINGACUTEMYOCARDIALINFARCTIONSkiBing;J.E.Hea... 相似文献
288.
戴雅康 《大连铁道学院学报》1989,10(3):61-68
本文通过对用铌磷半钢配制的中磷闸瓦的金相组织、力学性能、物理性能和摩擦-磨损特性的研究及其实际运行,证明:其质量指标和使用性能完全满足 TB1159-76标准,并超过普通中磷闸瓦的技术水平;可使中磷铸铁闸瓦的原材料成本降低10%左右. 相似文献
289.
290.
Comparison of All-Wheel Steerings in the System Driver-Vehicle 总被引:1,自引:0,他引:1
E. Ahring M. Mitschke 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1995,24(4):283-298
Different load or tires and a drive on an ice-coated road can overcharge a driver to such an extend, that the result may be an accident. Therefore the aim of development is a self-acting compensation of the vehicle to different vehicle transfer behaviour (invariant vehicle behaviour).
The calculation of so called optimal characteristics shows, that only rear-wheel steering cannot realize this aim of development. Therefore an additional front-wheel angle, which is not influenced by the driver, is necessary. A transfer function can be calculated in order to get controlled steering of the rear wheels without the influence of load.
It is not possible to realize optimal characteristics, because the parameters of the vehicle are difficult to measure. Only an optimal diagnosis and control of driving condition realize a relief for the driver in every driving situation in order to avoid most of the accidents.
The often demanded sideslip angle compensation only worsens driving conditions on ice-coated roads. Therefore systems which identify the driving condition themselves have to be favoured in any case. 相似文献
The calculation of so called optimal characteristics shows, that only rear-wheel steering cannot realize this aim of development. Therefore an additional front-wheel angle, which is not influenced by the driver, is necessary. A transfer function can be calculated in order to get controlled steering of the rear wheels without the influence of load.
It is not possible to realize optimal characteristics, because the parameters of the vehicle are difficult to measure. Only an optimal diagnosis and control of driving condition realize a relief for the driver in every driving situation in order to avoid most of the accidents.
The often demanded sideslip angle compensation only worsens driving conditions on ice-coated roads. Therefore systems which identify the driving condition themselves have to be favoured in any case. 相似文献