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171.
D. H. Koo J. C. Kim W. H. Yoo T. W. Park 《Transportation Research Part D: Transport and Environment》2002,7(6)
Wheel/rail interaction is a major source of railway noise. A low-noise wheel structure is developed and its effect on noise reduction is investigated. This low-noise wheel employs a rubber material inserted into the steel rim or mounted on the wheel surface. The low-noise wheel has low stiffness and a high-damping ratio compared to a solid wheel. Measurement shows that it reduces rolling and squealing. It turns out that a subway line with the proposed wheel could reduce its interior noise level by 4–5 dB(A) and vehicle vibration level by 7–8 dB. While the proposed structure seems promising in noise reduction for railway vehicles, the endurance and cost effectiveness of the low-noise wheel are yet to be verified. 相似文献
172.
173.
Analysis of a regenerative braking system for Hybrid Electric Vehicles using an Electro-Mechanical Brake 总被引:3,自引:0,他引:3
J. K. Ahn K. H. Jung D. H. Kim H. B. Jin H. S. Kim S. H. Hwang 《International Journal of Automotive Technology》2009,10(2):229-234
The regenerative braking system of the Hybrid Electric Vehicle (HEV) is a key technology that can improve fuel efficiency
by 20∼50%, depending on motor size. In the regenerative braking system, the electronically controlled brake subsystem that
directs the braking forces into four wheels independently is indispensable. This technology is currently found in the Electronic
Stability Program (ESP) and in Vehicle Dynamic Control (VDC). As braking technologies progress toward brake-by-wire systems,
the development of Electro-Mechanical Brake (EMB) systems will be very important in the improvement of both fuel consumption
and vehicle safety. This paper investigates the modeling and simulation of EMB systems for HEVs. The HEV powertrain was modeled
to include the internal combustion engine, electric motor, battery and transmission. The performance simulation for the regenerative
braking system of the HEV was performed using MATLAB/Simulink. The control performance of the EMB system was evaluated via
the simulation of the regenerative braking of the HEV during various driving conditions. 相似文献
174.
H. -D. Kang D. -H. Kim S. -W. Chae J. -N. Han D. -S. Kim 《International Journal of Automotive Technology》2009,10(5):583-587
Most of the research on safety belt systems has involved crash simulation that only considered a dynamic human model. However,
belt routing analysis, usually known as comfort level estimation, is also an important factor in safety belt design, considering
that serious injuries of the abdominal region result from the infiltration of a belt into the neck or the chest. Thus, safety
belt evaluations using kinematic human models are also needed. In this paper, a belt fit simulation method is suggested. Using
the proposed process, both comfort and safety analyses can be performed under the same conditions continuously, and thus the
safety belt design parameters, such as the location of anchor points, dummy posture and etc., can be evaluated. In conclusion,
this computer process enables a belt system design to reduce injuries. 相似文献
175.
In this study, a parallel flow condenser and laminated evaporator for an automotive air-conditioning system were modified
to improve performance. Gas-liquid separation type condensers, in which the condenser and receiver drier are integrated, and
one-tank laminated type evaporators were developed, and their performances were investigated experimentally using HFC-134a.
Heat transfer characteristics in the condenser are examined by means of air temperature, air velocity entering the condenser
and inlet pressure of the refrigerant; heat transfer characteristics in the evaporator are examined by means of air temperature,
relative humidity, flow rate of air, outlet pressure of refrigerant and superheat. Pressure drops for both evaporator and
condenser are also measured, and correlations for pressure drop are derived for the condenser and evaporator, respectively.
Air velocity and mass flow rate of the refrigerant have a significant effect on the overall heat transfer coefficient, and
flow pass is not significantly influenced by the cooling capacity of the condenser. The overall heat transfer coefficient
of the evaporator increases as air flow rate, air temperature and relative humidity increases. 相似文献
176.
Jennifer D. Ruiz-Ramírez Jorge I. Euán-Ávila Víctor H. Rivera-Monroy 《Coastal management》2019,47(1):23-43
We evaluated the potential economic impacts of increasing sea level rise (SLR) along the Mexican Caribbean where there are major gaps in our understanding of the mechanisms controlling flooding duration and frequency associated to future ecological and economic impacts. We determined the negative economic impact of SLR on infrastructure in the largest urban centers (Cancun, Isla Mujeres, Playa del Carmen, Puerto Morelos and Cozumel) in the state of Quintana Roo (Mexico) that are considered the largest tourism “hot spots” (resort cities) in the country. The tourism industry in this coastal area injects >8 billion dollars year?1 to the Mexican economy. Our conservative economic assessment regarding the impact of SLR, under a 1?m scenario for all coastal cities is $330 million USD. Further projections for worst scenarios (SLR >2 m) show a non-linear trend where the cost of inaction can reach up to $1.4 billion USD (2?m SLR scenario) and $2.3 billion USD (3?m SLR scenario). This potential loss of infrastructure, as construction cost, is staggering and represents a robust baseline to start evaluating with more detail future impacts of climate variability and change on the Mexican Caribbean coastline. 相似文献
177.
178.
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
179.
180.
Recent interpretations of carbon flux data and deep-sea processes have led to a reconsideration of the role of dissolved organic carbon (DOC) in supporting water column remineralization and other mid-water biogeochemical transformations (Suzuki et al., 1985; Cho and Azam, 1988; Karl et al., 1988; Christensen et al., 1989; Naqvi and Shailaja, 1993). To date, there have been no direct comparisons of particulate carbon flux data with water column metabolic rates. Here, for the first time, particulate carbon flux and respiratory electron transport activity (from which metabolic CO2 production is derived), have been monitored simultaneously for one year in the same area of the northwestern Mediterranean Sea. In the aphotic layer (200–1000 m), particulate organic carbon (POC) can support only 20% of the overall organic matter remineralization. Remineralization rates are consistent with recent calculations of DOC exported from the euphotic layer in this area, confirming the vital importance of DOC in maintaining deep-water metabolism. This finding would apply to other regions of mesotrophic and oligotrophic production and thus affect our understanding of carbon recycling in the water column, new production and O2 utilization. 相似文献