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71.
IlitroductlonNormallytemperaturemeasurementsareusedinaninverseheatconductionanalysis.lnarecelltinverseheatconductioninvestigation[ll,twodatatypes(temperatureandheating/coolingrate)weecomparedforthepurposeofinvestigatingtheireffectonpredictingthesurfaceheatfltixattheprojectedsurface.Itwasillustrated,vianumericalexample,thatthechoiceofinputdatainnuencesbOththeaccurasyandstabilityattheprojectedsurface.Thatis,thepredictionnotonlydePendsonthetemperaturedatabutimplicitlyitsillterpretedheating/cooli…  相似文献   
72.
In this paper a method of analysis of vehicle head-on collision, based on the concept of dispersion of stress waves in rods upon axial impact has been presented. The mathematical model of collision studied here described the vehicle behaviour in collision in terms of a one-dimensional, nonhomo-geneous, nonlinear partial differential equation. A procedure of model identification and some remarks concerning experimental data have been discussed. Results of computer simulation of a tested vehicle have been given.  相似文献   
73.
Network effects of intelligent speed adaptation systems   总被引:2,自引:0,他引:2  
Liu  Ronghui  Tate  James 《Transportation》2004,31(3):297-325
Intelligent Speed Adaptation (ISA) systems use in-vehicle electronic devices to enable the speed of vehicles to be regulated automatically. They are increasingly appreciated as a flexible method for speed management and control particularly in urban areas. On-road trials using a small numbers of ISA equipped vehicles have been carried out in Sweden, the Netherlands, Spain and the UK. This paper describes the developments made to enhance a traffic microsimulation model in order to represent ISA implemented across a network and the impact of this on the networks. The simulation modelling of the control system is carried out on a real-world urban network, and the impacts on traffic congestion, speed distribution and the environment assessed. The results show that ISA systems are more effective in less congested traffic conditions. Momentary high speeds in traffic are effectively suppressed, resulting in a reduction in speed variation which is likely to have a beneficial impact on safety. Whilst ISA reduces excessive traffic speeds in the network, it does not affect average journey times. In particular, the total vehicle-hours travelling at speeds below 10 km/hr have not changed, indicating that the speed control had not induced more slow-moving queues to the network. A statistically significant, eight percent, reduction in fuel consumption was found with full ISA penetration. These results are in accordance with those from field trials and they provide the basis for cost-benefit analyses on introducing ISA into the vehicle fleet. However, contrary to earlier findings from the Swedish ISA road trials, this study suggested that ISA is likely to have no significant effect on emission of gaseous pollutants CO, NOx and HC.  相似文献   
74.
Short-line railroad managers discuss their industry   总被引:1,自引:0,他引:1  
In the United States, the 1980 Staggers Rail Act created a positive regulatory environment for the creation of new short-line railroads. At present there are about 450 of these railroads that have less than 250 miles of trackage. This study asked managers/owners of these railroads two basic questions. First, what do you believe is the single most important trend that is currently taking place in your industry. The most frequently noted trend was the frustration of working with the larger Class 1 railroads. Five additional trends were also identified by the respondents. The second question asked the respondents if they thought the short-line sector of the rail industry will become more or less important in the next ten years and why. About 70% of the owner/managers believed their industry would become more important in the next decade. The most commonly expressed reason for this position is that the Class 1 railroads will increasingly specialize in mainline service only. Three other rationales were also enumerated. For the managers that thought their industry would become less important, the most noted reason was their trackage would not safely transport the newer very heavy bulk commodity freight cars.  相似文献   
75.
旅游客车制造业是一个既专业又特殊的行业。乍一看,它理应归属于汽车制造业;但从产品的实际情形以及相对较小的年产量来看,它又应归属于手工艺品行业;在这里可以看到,机械制造结合了手工艺,汽车造型融入了建筑艺术。这篇文章概述了伊利萨尔旅游客车的设计过程:从与客户的第一次  相似文献   
76.
The shelf-slope front (SSF) is a continuous shelf-break front running from the Tail of the Grand Banks to Cape Hatteras, North Carolina, separating colder and less-saline continental shelf waters from warmer and more saline slope waters. Time series containing mean monthly SSF positions were produced along each of 26 longitude lines between 75° and 50°W by workers located at Bedford Institute of Oceanography by digitizing individual frontal charts and computing mean monthly latitudinal positions over a 29-year (1973–2001) period. After removing seasonal variability at each longitude, interannual variability (IAV) of the SSF position at each longitude was computed as the annual mean of all monthly SSF position anomalies for each year over the 29-year period. Despite some missing data, a longitude-time plot reveals alternating bands of offshore (late-1970s, late-1980s, late-1990s) and onshore (early-1980s, early-1990s, early-2000s) annual mean SSF anomaly values, exhibiting a period of approximately 10 years. Annual mean SSF anomaly amplitudes are largest in the east, with maxima of O (± 100 km) located east of 60° W for years when data are available. Empirical orthogonal function (EOF) modes 1–4 (accounting for > 90% of the variance) form a set of basis functions that describe the SSF anomaly data and allow reconstruction of the entire data set since missing data are relatively few (14%). A complex empirical orthogonal function (CEOF) analysis using the “reconstructed” data reveals a wavelength scale of approximately 20° of longitude, a distance nearly equal to the entire study domain, along with steady, westward phase propagation of SSF anomalies over approximately the same distance. Speed calculations for the westward-propagating features yield a value of approximately 1.2 to 2.4 cm s− 1 (1 to 2 km d− 1), with annual mean SSF anomalies thus requiring about 4 years to propagate from the Tail of the Grand Banks in the east to Cape Hatteras, North Carolina, in the west. This propagation speed and the timing of the SSF positional anomalies at the Tail of the Grand Banks for the 29-year study period are in agreement with speeds computed for the propagation of quasi-decadal salinity anomalies through the Labrador Sea and the time of their arrival at the Tail of the Grand Banks. The small westward SSF anomaly propagation speed is an order of magnitude smaller than the associated currents, in agreement with a highly damped flow-through system originating from both Davis Strait and the West Greenland Current as discussed by other workers. Observations from both southern and northern portions of the study domain, within both continental shelf and slope waters, show that interannual changes in the volume of shelf water along with shelf water bulk properties exhibit a strong relationship with IAV of the SSF position over long time periods.  相似文献   
77.
Data from five separate field experiments during 2000–2006 were used to study the internal tidal flow patterns in the Gaoping (formerly spelled Kaoping) Submarine Canyon. The internal tides are large with maximum interface displacements of about 200 m and maximum velocities of over 100cm/s. They are characterized by a first-mode velocity and density structure with zero crossing at about 100 m depth. In the lower layer, the currents increase with increasing depth. The density interface and the along-channel velocity are approximately 90° out-of-phase, suggesting a predominant standing wave pattern. However, partial reflection is indicated as there is a consistent phase advance between sea level and density interface along the canyon axis.  相似文献   
78.
In this paper, we represent a systematic review of stated preference studies examining the extent to which cycle infrastructure preferences vary by gender and by age. A search of online, English-language academic and policy literature was followed by a three-stage screening process to identify relevant studies. We found 54 studies that investigated whether preferences for cycle infrastructure varied by gender and/or by age. Forty-four of these studies considered the extent of separation from motor traffic. The remainder of the studies covered diverse topics, including preferred winter maintenance methods and attitudes to cycle track lighting. We found that women reported stronger preferences than men for greater separation from motor traffic. There was weaker evidence of stronger preferences among older people. Differences in preferences were quantitative rather than qualitative; that is, preferences for separated infrastructure were stronger in some groups than in others, but no group preferred integration with motor traffic. Thus, in low-cycling countries seeking to increase cycling, this evidence suggests focusing on the stronger preferences of under-represented groups as a necessary element of universal design for cycling.  相似文献   
79.
80.
捷运潜盾隧道皆位于人口密集之都会区,潜盾机的发进与到达常为潜盾隧道挖掘过程中风险较大的时间点,本研究拟以潜盾机到达弃壳作业为例,探讨其面临之风险,包括点井降水造成地盘地下水位变化和邻近台电345 kV高压电塔不均匀沉陷,以及站体连续壁因开挖所引致侧向变位使JSG地盘改良区产生缝隙水路,造成潜盾机开舱前渗水的风险.再者,依据工址抽降水期间竖管式水压计、水位观测井和地表、建物沉陷点监测数据分析抽降水引致地表沉陷影响范围,用以回馈将来遭遇类似工况的设计参考依据.潜盾机到达之安全弃壳作业包括以超级点井(SWP)工法尝试降低地下水位,并于松三层(EL.92.42m)和松五层(EL.72.42m)埋设竖管式水压计了解降水期间地下水位变化,同时监测邻近建物如台电高压电塔的倾斜及沉陷;其次,在潜盾机到达处先行进行JSG地盘改良,再以试水试验检核地盘止水性,潜盾机到达后即进行机壳背填灌浆、土压舱分阶排土及漏水确认.然后,潜盾机历经二次拆解,完成到达弃壳作业,最后进行镜面破除及隧道贯通.  相似文献   
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