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31.
Gas transfer velocities of CO2 and CH4 in a tropical reservoir and its river downstream 总被引:4,自引:0,他引:4
Frdric Gurin Gwenaël Abril Dominique Sera Claire Delon Sandrine Richard Robert Delmas Alain Tremblay Louis Varfalvy 《Journal of Marine Systems》2007,66(1-4):161
We have measured simultaneously the methane (CH4) and carbon dioxide (CO2) surface concentrations and water–air fluxes by floating chambers (FC) in the Petit-Saut Reservoir (French Guiana) and its tidal river (Sinnamary River) downstream of the dam, during the two field experiments in wet (May 2003) and dry season (December 2003). The eddy covariance (EC) technique was also used for CO2 fluxes on the lake. The comparison of fluxes obtained by FC and EC showed little discrepancies mainly due to differences in measurements durations which resulted in different average wind speeds. When comparing the gas transfer velocity (k600) for a given wind speed, both methods gave similar results. On the lake and excluding rainy events, we obtained an exponential relationship between k600 and U10, with a significant intercept at 1.7 cm h− 1, probably due to thermal effects. Gas transfer velocity was also positively related to rainfall rates reaching 26.5 cm h−1 for a rainfall rate of 36 mm h− 1. During a 24-h experiment in dry season, rainfall accounted for as much as 25% of the k600. In the river downstream of the dam, k600 values were 3 to 4 times higher than on the lake, and followed a linear relationship with U10. 相似文献
32.
This study summarizes engine speed and load effects on HC species emissions from premixed charge compression ignition (PCI)
and conventional diesel combustion, and it evaluates diesel oxidation catalyst (DOC) formulations on a gas flow reactor for
the purpose of diesel particulate filter regeneration or lean NOx trap desulfation. HC emissions are sampled simultaneously by a Tedlar bag for light HC species and by a Tenax TA™ adsorption
trap for semi-volatile HC species, and they are analyzed by gas chromatography with a flame ionization detector. The bulk
temperature and residence time during combustion are key parameters that are important for understanding the effects of speed
and load on engine-out HC emissions. The degree of post-flame oxidation is higher in PCI than in conventional combustion,
and it is increased for PCI with a higher speed and load, as indicated by a lower fuel alkanes/THC ratio, a higher alkenes/fuel
alkanes ratio, and a higher methane/THC ratio. Ethene and n-undecane are two representative HC species, and they are used
as a surrogate mixture in the gas flow reactor to simulate PCI and conventional combustion with in-cylinder post fuel injection.
Among the three DOC formulations tested, the catalyst with constituent precious metals of platinum and palladium (PtPd) showed
the best light-off performance, followed by PtPd with an addition of cerium dioxide (PtPd+CeO2), and platinum (Pt), regardless of exhaust compositions. Conventional combustion exhaust composition shows a lower light-off
temperature than that of PCI, regardless of catalyst formulation. 相似文献
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利用热经济学的研究方法对燃气热泵和其它几种常规空调方式的经济性进行了研究比较,并就能源价格变化对经济性的影响进行了研究,获得了适宜燃气热泵推广应用的能源价格范围。结果表明,燃气热泵的年度总成本最低,具有经济性优势。 相似文献
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李煜平 《城市轨道交通研究》2020,(3):179-182
为实现各种新型互联网支付在地铁的统一应用,分析了建立地铁互联网票务平台的必要性以及平台的总体架构、主要功能、部署方式等。方案表明,互联网票务平台的建设,可以实现地铁各种“互联网+”应用的统一管理,为各种新型互联网支付应用在地铁的快速发展打下坚实基础。 相似文献
38.
A potential solution to reduce greenhouse gas (GHG) emissions in the transport sector is the use of alternative fuel vehicles (AFV). As global GHG emission standards have been in place for passenger cars for several years, infrastructure modelling for new AFV is an established topic. However, as the regulatory focus shifts towards heavy-duty vehicles (HDV), the market diffusion of AFV-HDV will increase as will planning the relevant AFV infrastructure for HDV. Existing modelling approaches need to be adapted, because the energy demand per individual refill increases significantly for HDV and there are regulatory as well as technical limitations for alternative fuel station (AFS) capacities at the same time. While the current research takes capacity restrictions for single stations into account, capacity limits for locations (i.e. nodes) – the places where refuelling stations are built such as highway entries, exits or intersections – are not yet considered. We extend existing models in this respect and introduce an optimal development for AFS considering (station) location capacity restrictions. The proposed method is applied to a case study of a potential fuel cell heavy-duty vehicle AFS network. We find that the location capacity limit has a major impact on the number of stations required, station utilization and station portfolio variety. 相似文献
39.
代中军 《铁路工程造价管理》2014,(5):18-21
铁建设[2010]223号文发布的《铁路工程预算定额》的新版隧道工程定额,其子目的设置吸纳了先进的施工技术、施工组织模式及工艺工法,体现了进行“四化”施工的要求。那么设计单位的工程经济人员如何正确理解和使用新版隧道定额,尤其是遇到新版定额缺项时如何分析套用相近定额子目,此文结合客运专线某隧道工程,就如何计算开挖正洞隧道出砟和衬砌混凝土的运距、确定工程量、编制概算,进行分析与论述。并针对隧道工程概预算编制中辅助坑道开挖隧道出砟及衬砌混凝土存在的争议,提出见解。 相似文献
40.
周璐川 《城市轨道交通研究》2014,17(11)
由于客流调查的局限性、网络乘客出行行为的差异性等因素的影响,需要进一步研究清分模型及客流分布计算结果的准确性及模型中的相关参数.介绍了城市轨道交通现有客票收入清分模型.依托上海轨道交通AFC(自动售检票)系统提供的基础数据,对清分模型参数进行灵敏度分析,提出了提高现有清分准确度的方法和手段. 相似文献