全文获取类型
收费全文 | 285篇 |
免费 | 3篇 |
专业分类
公路运输 | 105篇 |
综合类 | 11篇 |
水路运输 | 91篇 |
铁路运输 | 13篇 |
综合运输 | 68篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 17篇 |
2013年 | 44篇 |
2012年 | 15篇 |
2011年 | 16篇 |
2010年 | 9篇 |
2009年 | 13篇 |
2008年 | 18篇 |
2007年 | 14篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有288条查询结果,搜索用时 328 毫秒
21.
J. H. Yoon B. J. Choi I. H. Yang J. E. Oh 《International Journal of Automotive Technology》2011,12(1):59-66
T-Hypoid gears are commonly used in rear-drive and 4WD (4 Wheel Drive) vehicle axles. Investigating their sensitivity to deflections
is one of the most important aspects of their design and optimization procedures. Therefore, a deflection test was performed
in this study in the actual gear mounting using completely processed gear. This test covered the full operating range of gear
loads from “no load” to “peak load”. Under peak load, the contact pattern extended to the tooth boundaries without showing
a concentration of the contact pattern at any point on the tooth surface. The transmission error was tested under an axle
assembly triaxial-real-car-load condition. 相似文献
22.
License plate extraction method for identification of vehicle violations at a railway level crossing
B. K. Cho S. H. Ryu D. R. Shin J. I. Jung 《International Journal of Automotive Technology》2011,12(2):281-289
The primary cause of most railroad accidents is vehicle entry into railway level crossings despite warning messages. To identify
drivers who violate railway level crossing regulations, vehicle license plate recognition can be applied at railway level
crossings. The purpose of this paper is to present an effective method for extracting the license plate region from vehicle
images taken at railway level crossings. The method proposed in this paper uses the variation in the gray-level values across
the image of a license plate. For license plate region extraction, the character region is first recognized by identifying
the character width and the difference between the background region and the character region. The license plate region is
then extracted by finding the inter-character distance in the plate region. In addition, the license plate type is identified
by the difference in the gray-level value between the background region and the character region. The proposed method is effective
in solving the current challenges in extracting the license plate region from the damaged frames of license plates issued
for domestic use, including new types of license plates. According to the experimental results, the proposed method yields
a high extraction rate of 99.5% for vehicle license plates. 相似文献
23.
K. Jang I. Park J. Han K. Lee M. Sunwoo 《International Journal of Automotive Technology》2011,12(4):589-597
Because the FlexRay protocol has more than 70 configuration parameters and these parameters correlate with each other, designing
a FlexRay network is a complex and difficult task. In this study, we propose a design framework that optimizes the two main
FlexRay network parameters that are highly relevant to the application algorithm. The design process is composed of two steps
for optimizing parameters. In the first step, the static slot length is optimized using a frame-packing algorithm. This algorithm
binds network signals into static frames based on their periods and signal groups. In the second step, the communication cycle
length is optimally designed with frame-scheduling algorithm and worst-case reponse time analysis. Based on the frame-scheduling
algorithm, the response times are analyzed. The proposed design framework was applied to a unified chassis control system
as a case study, and the analytical results were verified. 相似文献
24.
H. H. Lee H. W. Bang S. K. Kauh S. I. Kim 《International Journal of Automotive Technology》2011,12(3):351-358
The development of an inner-piston-chamber temperature measurement system is a necessary step in engine development or when
solving other fundamental problems related to automotive engines. There are various pre-existing measurement methods available,
e.g., the linkage method, piston telemetry, templog, and the electromagnetic induction method. In this study, we first redesigned
the coil sensor used in the electromagnetic induction method using PEEK and then used Taguchi methods to reduce the number
of experiments in the development process and finally utilized piston telemetry via Bluetooth to verify the precision and
accuracy of the redesigned PEEK coil sensor and electromagnetic induction method. The results displayed a reproducibility
within 0.5 degrees and an accuracy within 2 degrees Celsius. 相似文献
25.
D. H. Kim J. M. Lee E. H. Park J. H. Song S. I. Park 《International Journal of Automotive Technology》2011,12(3):409-416
A comprehensive study evaluating the performance of biobutanol-blended gasoline in passenger cars was conducted because biobutanol
is considered a better biofuel than bioethanol as it has no water solubility and it has a higher caloric value, giving it
a higher energy value. Several kinds of samples—suboctane gasoline, 8 volume percentage and 16 volume percentage biobutanol—blended
gasoline, and a 10 volume percentage MTBE-blended market sample (as the oxygencontaining gasoline)-were tested to evaluate
the engine performance in terms of the detergency of the intake valves and combustion chambers, power, emissions, and fuel
efficiency. Additionally, the toxicity of the emissions from these biobutanolblended samples was tested in order to assess
the viability of biobutanol as one of the competitive potential substitutes for MTBE as an oxygenator in the near future.
The results show that biobutanol-blended gasoline samples had relatively better detergency, relatively higher power, and similar
levels of emissions compared with those of MTBE-blended gasoline. Formaldehyde was emitted from all of the samples at almost
the same levels and within the error range, whereas biobutanolblended gasoline samples emitted approximately three times the
amount of acetaldehyde than did the suboctane gasoline. This study shows that biobutanol is one of the best alternative bioalcohol
fuels for use in the near future. 相似文献
26.
This paper discusses the final investigation into the effect of fuel stratification on flame propagation. In previous works,
the characteristics under the no port-generated swirl condition and the low-swirl condition were considered. For this purpose,
the initial flame development and propagation were visualized under different axially stratified states in a modified optical
single-cylinder SI engine. The images were captured by an intensified CCD camera through the quartz window mounted in the
piston. Stratification was controlled by the combination of the port swirl ratio and injection timing. These were averaged
and processed to characterize the flame propagation. The flame stability was estimated by the weighted average of flame area
and luminosity. The stability was also evaluated through the standard deviation of flame area and propagation distance and
through the mean absolute deviation of the propagation direction. The results show that the LML is expanded remarkably under
the high-swirl cases up to the highest relative AFRs of 1.71 and 1.75 between 140 and 160CA. In addition, similar to the low-swirl
condition, the flame-flow interaction determines the direction of flame propagation, and the governing roles of the two factors
vary according to the swirl level; the flow is more important at the higher swirl conditions, and the flame is more important
at the lower swirl condition. Finally, fast and stable flame propagation can be achieved under the preferably stratified condition,
which is induced by the suitable combination of the high swirl and injection timing. 相似文献
27.
28.
29.
Primary production events in both the Arctic and the Antarctic are highly localized. Carbon-14 incubations that did not account for this caused antarctic primary production estimates to be revised too far downwards from the historic view of high productivity. The primary production regime in the Arctic is even more heterogeneous than in the Antarctic. Arctic primary production rates are in the process of being revised upwards because of a better spatial and temporal distribution of incubation experiments and a re-awakening of interest in estimating new production from the distribution of chemical variables. Similarly, recent examination of temporal changes in nitrate concentrations and recognition of the importance of ice-edge blooms has caused antarctic primary productivity to be revised upwards. In both the Arctic and the Antarctic, the ratio of “new” to total primary production is high, and neglect of this fact can lead to an underestimation of the potential that these regions have for influencing global cycles of bioactive chemicals. Some recent data on temporal changes in nitrate from Fram Strait emphasize the poor state of our knowledge by suggesting an unexpectedly high “new” production rate of 1 g C m−2 d−1 for a 35 day experiment that encountered an early Phaeocystis bloom. Chemical distributions suggest that new production over the shelf seas that border the Polar Basin is about 50 g Cm−2 yr−1.The shelves in the Arctic Ocean's marginal and adjacent seas comprise 25% of the total global continental shelf. These extensive shallow regions have much higher rates of primary production than the Polar Basin and may be globally significant sites of denitrification. Globally significant silica deposition could occur on these shelves or on the adjacent slopes.Because of the differences in geomorphology and stratification, global warming is likely to increase primary production in the Arctic and will probably decrease antarctic primary production.In addition to sharing high ratios of “new” to total primary production, high ammonium concentrations occur in the Arctic and Antarctic. It is possible that these accumulations arise from a strong repression of nitrification at low temperatures. 相似文献
30.
Marine ecosystem models are becoming increasingly complex and sophisticated, and are being used to estimate the effects of future changes in the earth system with a view to informing important policy decisions. Despite their potential importance, far too little attention has been, and is generally, paid to model errors and the extent to which model outputs actually relate to real-world processes. With the increasing complexity of the models themselves comes an increasing complexity among model results. If we are to develop useful modelling tools for the marine environment we need to be able to understand and quantify the uncertainties inherent in the simulations. Analysing errors within highly multivariate model outputs, and relating them to even more complex and multivariate observational data, are not trivial tasks. Here we describe the application of a series of techniques, including a 2-stage self-organising map (SOM), non-parametric multivariate analysis, and error statistics, to a complex spatio-temporal model run for the period 1988–1989 in the Southern North Sea, coinciding with the North Sea Project which collected a wealth of observational data. We use model output, large spatio-temporally resolved data sets and a combination of methodologies (SOM, MDS, uncertainty metrics) to simplify the problem and to provide tractable information on model performance. The use of a SOM as a clustering tool allows us to simplify the dimensions of the problem while the use of MDS on independent data grouped according to the SOM classification allows us to validate the SOM. The combination of classification and uncertainty metrics allows us to pinpoint the variables and associated processes which require attention in each region. We recommend the use of this combination of techniques for simplifying complex comparisons of model outputs with real data, and analysis of error distributions. 相似文献