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751.
According to the Belgrade Master Plan for 2021, the public transportation system for the city and its region will include three rail modes: a modernized existing tramway, regional rail, and a new light rail transit (LRT) mode. In the coming years all three rail modes should be developed simultaneously and in a coordinated manner. The introduction of LRT is to be realized in several phases, and its first line will partially follow the alignment of an existing tramway line. As the present tramway vehicles are obsolete, new rolling stock must be designed and purchased to be compatible with many of the elements of the LRT. Ways to adjust the new tramways to the LRT rolling stock represent the central topic of this paper. The basic technical and operating characteristics of the new tramway are defined with respect to their required compatibility with the LRT stock and infrastructure. 相似文献
752.
This paper considers the problem of freeway incident detection within the general framework of computer‐based freeway surveillance and control. A new approach to the detection of freeway traffic incidents is presented based on a discrete‐time stochastic model of the form ARIMA (0, 1, 3) that describes the dynamics of traffic occupancy observations. This approach utilizes real‐time estimates of the variability in traffic occupancies as detection thresholds, thus eliminating the need for threshold calibration and lessening the problem of false‐alarms. Because the moving average parameters of the ARIMA (0, 1, 3) model change over time, these parameters can be updated occasionally. The performance of the developed detection algorithm has been evaluated in terms of detection rate, false‐alarm rate, and average time‐lag to detection, using a total of 1692 minutes of occupancy observations recorded during 50 representative traffic incidents. 相似文献
753.
搅拌工具轴肩和搅拌头轮廓对铝合金搅拌摩擦焊的影响一对比研究(英文) 总被引:1,自引:0,他引:1
In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to steel.In this paper a study on friction stir welding of aluminum alloys was presented.The present investigation deals with the effects of different friction stir welding tool geometries on mechanical strength and the microstructure properties of aluminum alloy welds.Three distinct tool geometries with different types of shoulder and tool probe profiles were used in the investigation according to the design matrix.The effects of each tool shoulder and probe geometry on the weld was evaluated.It was also observed that the friction stir weld tool geometry has a significant effect on the weldment reinforcement,microhardness,and weld strength. 相似文献
754.
Comment by John R. Clark Comment by Kem Lowry Comment by Stephen B. Olsen Response by Jens Sorensen 相似文献
755.
Robert R. Kifer 《Coastal management》2013,41(2):177-188
Abstract Authority to designate marine sanctuaries was established by Title III of the Marine Protection, Research, and Sanctuaries Act of 1972. One may view this authority as the ocean water counterpart to our National Parks and Seashores. Contained herein is a discussion of the components of the Title and how the National Oceanic and Atmospheric Administration (NOAA) plans to carry out the program. Nominations received to date are briefly discussed. 相似文献
756.
K. S. Tan S. V. Wong R. S. Radin Umar A. M. S. Hamouda N. K. Gupta 《International Journal of Automotive Technology》2009,10(3):329-339
Experiments were conducted to investigate the influence of certain parameters that affect the impact response of the motorcycle
front wheel-tire assembly under various impact conditions. Impact tests were conducted according to 2
ν
5 − 1 fractional factorial design using a pendulum impact test apparatus with impact speed, impact mass, tire inflation pressure
level, striker geometry, and impact location as design factors. Significant factors influencing the response of the wheel-tire
assembly were identified. Coefficients for each factor were also determined, and empirical models were then developed for
each response. An analysis indicates that the developed models fit well within the experimental ranges of the respective factors.
However, for several interaction effects, the models become unrealistic, whereby they give certain deformation values when
approaching zero impact mass and/or zero impact velocity. This is not consistent with the mechanics of the physical world,
as there should not be any significant deformation when delivered impact energy is small enough. Efforts have been made in
developing better models to resolve the inconsistency and to include a wider range, especially considering the case of the
lower limit of experimental factors, which are an impact mass of 51.18 kg and/or an impact velocity of 3 m s−1 (10.8 km/h) down to zero. The minimum amount of impact energy required to produce the onset of observable deformation on
the wheel was incorporated in the development of new models. Finally, the present models have been developed not only to cover
the lower regions but also to range up to the upper limits of the factors, which are an impact mass of 101.33 kg and an impact
velocity of 6 m s−1 (21.6 km/h). 相似文献
757.
758.
759.
Increase in particle number emissions from motor vehicles due to interruption of steady traffic flow
E.R. Jayaratne L. Wang D. Heuff L. Morawska L. Ferreira 《Transportation Research Part D: Transport and Environment》2009,14(7):521-526
We assess the increase in particle number emissions from motor vehicles driving at steady speed when forced to stop and accelerate from rest. Considering the example of a signalized pedestrian crossing on a two-way single-lane urban road, we use a complex line source method to calculate the total emissions produced by a specific number and mix of light petrol cars and diesel passenger buses and show that the total emissions during a red light is significantly higher than during the time when the light remains green. Replacing two cars with one bus increased the emissions by over an order of magnitude. 相似文献
760.
W. Perret R. Thater U. Alber C. Schwenk M. Rethmeier 《International Journal of Automotive Technology》2011,12(6):895-901
Fusion welding processes are widely used for joining metal structures, such as pipes, ships, and cars. In general, these joining
processes offer a very good compromise between reliability, safety, cost and maintenance which are important issues in the
current economical context. The negative heat effects of welding, i.e. distortions and residual stresses of the welded parts,
are well known and many researches in this field have already been done in the last decades in order to minimize them. On
the experimental side, many sophisticated procedures have become state of the art to deal with this problem. On the computational
side, the improvement of the simulation algorithms and the computing power enables the simulations of many physical phenomena
occurring during the welding process. The implementation of welding simulation techniques is nevertheless not an easy task
and often associated with expert knowledge which hinders their global application in an industrial environment. This paper
is focused on the industrial requirements of a welding simulation software with special respect to the needs of the automotive
industry. The necessary information to run a welding simulation and the expectations of a weld specialist without deep knowledge
in numerical methods are investigated. These expectations are tested on an automotive welded assembly with a commercially
available welding simulation software designed especially for the needs of the automotive industry. A welding experiment is
done and the measured temperature distributions and distortions serve as reference to validate the simulation results. The
result quality of the simulations of temperature fields and distortions is in best agreement with experimental data. The workflow
is well adapted for the considered industrial requirements and the time-tosolution as well as the computational costs are
acceptable, whereas the efficient calibration of the heat input model is still a point which will be further investigated
in current and future research works. 相似文献