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101.
102.
Yusuke Tahara Robert V. Wilson Pablo M. Carrica Frederick Stern 《Journal of Marine Science and Technology》2006,11(4):209-228
Steady flow simulations for the Korean Research Institute for Ships and Ocean Engineering (KRISO) container ship (KCS) were
performed for towing and self-propulsion. The main focus in the present article is on the evaluation of computational fluid
dynamics (CFD) as a tool for hull form design along with application of state-of-the-art technology in the flow simulations.
Two Reynolds-averaged Navier-Stokes (RANS) equation solvers were employed, namely CFDShip-Iowa version 4 and Flowpack version
2004e, for the towing and self-propulsion cases, respectively. The new features of CFDShip-Iowa version 4 include a single-phase
level-set method to model the free surface and an overset gridding capability to increase resolution in the flow and wave
fields. The new features of Flowpack version 2004e are related to a self-propulsion scheme in which the RANS solver is coupled
with a propeller performance program based on the infinitely bladed propeller theory. The present work is based on a close
interaction between IIHR-Hydroscience and Engineering of the University of Iowa and Osaka Prefecture University. In the following
article, overviews are given of the present numerical methods and results are presented and discussed for the KCS in towing
and self-propulsion modes, including comparison with available experimental fluid dynamics (EFD) data. Additional evaluation
is provided through discussion of the recent CFD Workshop Tokyo 2005, where both methods appeared to yield very promising
results. 相似文献
103.
An efficient algorithm for building min-path trees for all origins in a multi-class network 总被引:1,自引:0,他引:1
Urban transportation planning models consume untold hours of computer time building zillions of min-path trees. Their networks have tens of thousands of arcs, accommodate several trip classes, and solve the traffic equilibrium problem via many, many iterations of min-path calculations for thousands of origins and destinations. This paper presents a simple algorithm that couples restricted reduced-cost analysis with label-correcting, which can reduce this min-path tree building time substantially. For a given origin, the algorithm rapidly transforms a tree for one class to that for next class. Test results using synthetic data suggest that its application to real networks should experience speedups of at least a factor of 2.0 and perhaps beyond 5.0. 相似文献
104.
J. Lucas M. A. Houghton I. G. Masheter 《International Journal of Automotive Technology》2012,13(6):853-860
A system has been researched over the past 3 years for reducing the exhaust pollutants from diesel engines for light commercial vehicles. The system researched achieves Euro 6 standards for reduction of polluting gases (CO, HC, PM, NO). It consists of 4 main sections: 1. A heater and heat exchanger (HE); 2. A CO/HC oxidising catalyst (D°C); 3. Pt catalyst on a diesel particulate filter (DPF); 4. A NO reducing reaction (SCR) within the DPF. The system operates as follows. The exhaust gas contains oxidising gases, namely both O2 and NO2. The levels of CO and HC are oxidised by O2 to CO2 for temperatures above 200°C. Carbon (PM) is oxidised to CO2 by NO2 but requires a temperature above 250°C. The operating exhaust temperature of 300°C is ideal for the removal of NO by using the Pt catalyst and the CO generated within the DPF. The heater is required to be able to raise the exhaust temperature at any time to 300°C in order to optimise the performance of the system, since diesel engine exhaust temperatures vary between 160°C (slow speeds) to 350°C (high speeds). Considerable heat is required (??3 kW) to maintain the exhaust gas for a 2l engine at 300°C for engine idle conditions. Therefore a heat exchanger is required to re-circulate the input heat and thereby reduce the maximum power consumption to a maximum of 500W over the engine full operating test cycle. This energy is supplied by the engine battery and alternator. Experimental results have been obtained for the exhaust from a Kubota diesel engine and the reductions in exhaust emissions of 83% (CO/ HC), 58% (NOx) and 99% (PM) were obtained. The PM was continuously cleaned so that there was no build up of back pressure. 相似文献
105.
Robert Pomeroy John Parks Kathleen Reaugh-Flower Mar Guidote Hugh Govan Scott Atkinson 《Coastal management》2015,43(3):301-328
Combating illegal and destructive resource exploitation in the Coral Triangle is central to ensuring the long-term effective management of fisheries, marine protected areas, and climate change adaptation efforts. This article presents results of an investigation of the perceived level of local compliance and enforcement with marine resource rules and regulations and evaluates the effectiveness or potential for community-supported enforcement efforts in the Coral Triangle region. The findings are consistent with those of the literature on compliance and enforcement that any compliance and enforcement system must not only use deterrence, but also be perceived by fishers as being legitimate, fair, accountable and equitable and the need for developing a personal morality and a social environment that supports compliance. There is an opportunity to strategically build on shared value and cultural norms that can promote collaborative fisheries management as a mechanism to increase compliance through non-coercive efforts. Strengthening the long-term capacity for consistent delivery of local support to marine management and enforcement will increase local compliance rates through time. 相似文献
106.
加拿大幅员辽阔,但人口稀少(大约3000万人).由于气候地理的原因,90%的加拿大人居住在与美国邻界322 km宽的窄带内.另外,加拿大的大多数人,确切地说是76.6%,居住在城市和城镇,只有23.4%的人居住在乡村.因此,加拿大的城市发展问题十分重要.多伦多、蒙特利尔、卡尔加里、温哥华等城市已发展成为国际大都市,多种经济形式并存,服务业十分发达,还有银行、工程、医药和科学研究等. 相似文献
107.
Robert G.V. Baker 《Transportation Research Part B: Methodological》1981,15(5):319-327
The study of traffic flow dynamics is developed by defining and clarifying traffic divergence, continuity, congestion and dispersion. Velocity potential is introduced as a gravity function generated by the interaction of two or more motorists occupying neighbouring points in space and describes interference to continuous traffic flow. The relationship between the potential function and carrying capacity is developed and dispersion, when considered as a random walk, satisfies a diffusion equation. A model of traffic dispersion along a maximum congested road in space and time is presented as eigenfunctions of the velocity potential. This suggests that traffic can be dispersed by a series of quantum steps. A probability density function is introduced to define the probability of locating a motorist in a congestion zone. 相似文献
108.
This paper examines developments in container shipping in light of the formation of strategic alliances by many of the leading companies. It focuses on three features: the transformation of services, the evolution of the fleet, and the adjustments made to the ports of call. These elements are analysed on a global basis for 3 years: 1989, 1994 and 1999. Some of the changes wrought by the alliances are identified, including the spread and intensification of services, and the deployment of the largest vessels on alliance routes. While the individual companies that have come together in alliances are serving many more ports than before, it is also demonstrated that the total number of ports served by the industry has remained constant. The results are interpreted in the context of globalization that is tending to impose greater standardization on the container shipping industry. 相似文献
109.
The Cocos (Keeling) Islands are located on an isolated atoll in the Indian Ocean and have a strong Malay culture owing to the translocation of a substantial plantation workforce in the early 19th century. The atoll became one of Australia's External Territories in 1955. Meeting the marine resource needs of the atoll residents within an Australian legislative system by formulating an integrated marine management plan presented several challenges. Key factors in drafting a culturally meaningful plan were a commitment to understanding and accommodating the cultural and subsistence needs of the community, innovative communication strategies, and a simple approach to management. Development of the plan highlighted the limitations of current Australian marine planning legislation in cross-cultural settings and for sustainable development. 相似文献
110.
Robert J. Johnston Thomas A. Grigalunas James J. Opaluch Marisa Mazzotta Jerry Diamantedes 《Coastal management》2013,41(1):47-65
This article summarizes four integrated economic studies undertaken to contribute to resource preservation and restoration decisions for the Peconic Estuary System of Suffolk County, NY. Completed as part of the National Estuary Program, the studies apply distinct resource valuation methods to a wide range of resource issues. The principal goals of this article are to highlight different methodologies that may be used to assess nonmarket economic values in a coastal management context, and characterize differences in the results that one may expect from each approach. We also emphasize potential relationships among values estimated by different nonmarket methodologies, and comment on the implications of these relationships for the interpretation and use of economic value estimates. 相似文献