全文获取类型
收费全文 | 849篇 |
免费 | 5篇 |
专业分类
公路运输 | 240篇 |
综合类 | 20篇 |
水路运输 | 279篇 |
铁路运输 | 21篇 |
综合运输 | 294篇 |
出版年
2022年 | 16篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 22篇 |
2017年 | 23篇 |
2016年 | 27篇 |
2015年 | 11篇 |
2014年 | 30篇 |
2013年 | 120篇 |
2012年 | 30篇 |
2011年 | 35篇 |
2010年 | 42篇 |
2009年 | 34篇 |
2008年 | 40篇 |
2007年 | 15篇 |
2006年 | 22篇 |
2005年 | 23篇 |
2004年 | 12篇 |
2003年 | 24篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 18篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 17篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 10篇 |
1972年 | 5篇 |
排序方式: 共有854条查询结果,搜索用时 218 毫秒
791.
Partial range scaling method based washout algorithm for a vehicle driving simulator and its evaluation 总被引:2,自引:0,他引:2
M. S. Kim Y. G. Moon G. D. Kim M. C. Lee 《International Journal of Automotive Technology》2010,11(2):269-275
Unlike an actual vehicle, a vehicle driving simulator (VDS) has limited kinematics, workspace, and bounded dynamic characteristics
making it very difficult to simulate dynamic motions of an actual vehicle. To solve these problems, a washout algorithm was
developed. The developed algorithm restricts the workspace of the VDS to within the kinematic limit and makes the person driving
the VDS perceive movement of an actual vehicle. However, the classic washout algorithm contains several problems, such as
time delay and the generation of a wrong motion signal caused by characteristics of the filters. So the driver feels “simulator
sickness,” such as fatigue, nausea, headache and so on because of differences between the sense of movement of the VDS and
that of a real vehicle. In this paper, a partial range scaling method based washout algorithm, including a tilt coordination
system, is developed to enhance the perception of motion and reduce simulator sickness. It is verified by a simulation, a
survey, and a bio signal analysis using an electrocardiogram (ECG). 相似文献
792.
Parametric optimization is an important step for any mechanical system design, including the development and design of a hybrid
electric bus. To obtain an optimized parameter grouping of the EQ6110HEV hybrid electric bus for best fuel economy, an orthogonal
experiment design method is applied to the parameter optimization process of the EQ6110HEV hybrid prolusion system. This paper
proposes two orthogonal experiment methods; the basically orthogonal experiment method and the synthetically orthogonal experiment
method. By this means, the development time and the testing costs are reduced, and the impact of factors and their optimal
levels are obtained by a range analysis of the experiment results. The results show that the fuel economy of the optimized
parameter grouping is improved by 4.1 percent for the four-stage urban driving cycle in China and by 8.7 percent for the Wuhan
urban driving cycle of public buses in China, in comparison with that of the parameter grouping of the current configuration. 相似文献
793.
S. I. Kim G. H. Lee J. J. Lee J. P. Hong 《International Journal of Automotive Technology》2010,11(2):277-282
In this paper, a simple design method for improving the performance of an interior permanent magnet synchronous motor (IPMSM),
for driving the air-conditioning compressor used in hybrid electric vehicles, is presented. There are many design methods
that optimize the IPMSM. Each method deals with a variety of design factors, such as slot opening, pole arc, and rotor shape.
However, as the number of design variables increases, a lot of modeling and analysis time is needed in order to improve the
characteristics of an IPMSM. This paper demonstrates that the optimization of a double-layer IPMSM, satisfying the given design
conditions, is possible with only a flux barrier shape design. Then, response surface methodology is applied as the optimization
method, and the validity of the design approach is verified by comparison with test results. 相似文献
794.
795.
A.G. Thompson B.R. Davis 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1990,19(3):131-149
In pantographs used for current collection on high speed electric trains it is desirable to minimise the fluctuations in the contact force between the collector head and the catenary. A simple two-mass linear model is employed for the pantograph and the design of the proposed control system is based on the input admittance at low frequencies. Frequency shaping is incorporated in the performance index, and a simple dynamic controller is employed to achieve optimality in an equivalent transformed system, while minimising the number of feedback quantities to be measured. A significant reduction in the average contact force appears possible. 相似文献
796.
A combined observational-modeling study was conducted to investigate turbulence mixing, and the relation to surface forcing, in the surface boundary layer (SBL) of a tropical, high-altitude, freshwater reservoir. A suite of vertical profiles of temperature microstructure, collected at three different stations of one-day duration each, provided estimates of dissipation rates of turbulence kinetic energy, , and temperature variance, χ. Numerical simulations of and χ, using state-of-the-art, public domain, two-equation turbulence closure models, compared favorably with the observations and reproduced the dynamics of daytime wind mixing as well as the vertical and temporal turbulence structure during nighttime convective conditions.Two independent estimates of vertical eddy diffusivities in the stably stratified (daytime) SBL, computed from the microstructure measurements, agreed closely, and the near surface heat and buoyancy fluxes, computed from the diffusivities, were similar to those computed independently from surface meteorology. Model generated eddy diffusivities agreed closely with the observed values, except those generated by K profile parameterization (KPP) model simulations. The good agreement provides confidence that nutrient fluxes in the SBL may be accurately computed from the models when forced with regularly measured surface meteorological parameters. The consequences are important for estimation of daily primary productivity rates in the euphotic zone and the ability to predict algal blooms such as those observed in the present reservoir. 相似文献
797.
P. Bolzern F. Cheli G. Falciola F. Resta 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1999,31(1):23-34
The paper discusses the application to real data of an identification procedure based on an Extended Kalman Filter, for estimating the equivalent non-linear suspension tyre cornering forces of a road vehicle from a single standard manoeuvre. In particular, both the steady-state and the dynamic handling characteristics can be evaluated. 相似文献
798.
Realistic predictions of the likely safety performance of advanced transport systems will need to draw on the knowledge accumulated from a large number of safety evaluations which have already been undertaken for existing transport systems. In particular, safety evaluations of future technologies must avoid the methodological pitfalls experienced in extensively researched areas, such as road safety, if such evaluations are to be meaningful. This paper reviews the use of exposure for a broad range of road safety studies, and concludes that unsatisfactory treatment of exposure is a common failing in past evaluations of the effectiveness of road accident countermeasures. Whilst a broad range of safety analyses is discussed, the use of exposure in site safety studies is emphasized. A follow-up paper will extend the discussion to other aspects of accident exposure including exposure measures for large groups of transport system users. 相似文献
799.
800.
G. Levikov 《Maritime Policy and Management》1988,15(3):247-254
In light of the Reveiw Conference on the UN Code of Conduct for Liner Conferences to be in November 1988, this paper highlights some of the Major problems impinging upon the universal acceptability of the Code. These include the reservation (known as the Brussels Package) by EC and certain other OECD countries that discriminates aganist developing and Socialist countries; reservations of a controversial nature with regard to the establishment of joint shipping lines established on the basis of intergovernmental bilateral agreement; and the question of compctition by non-conference lines that diminishes the share of cargo available to National Lines by virtue of the Code. 相似文献