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561.
The comprehensive analysis presented in this paper investigates the links and comparative assets between human factor and
other factors that are important determinants of maritime transport risk. In this outline, the identification of factors,
such as age and ship size, that can be statistically linked (i.e. statistical significance) to whether an accident in a passenger
vessel can be attributed to human factor or other causes is addressed accordingly. This way, the role of human factor in relation
to safety of Greek coastal shipping is revealed and the spotlight is able to focus on the various aspects and points that
manifest the importance of human element in the maritime industry. The risk assessment of the transportation with Greek passenger
ships is being used in order for the safety level of Greek coastal shipping to be adequately estimated. Moreover, the comparison
between the values of risk for accidents caused by human factor and those attributed to other causes is an established way
to bring to the fore the unbroken relationship between the human factor and marine accidents’ consequences. The paper is concluded
with interesting insights and comments drafted through the aforementioned tasks. 相似文献
562.
H. Thiel K.-O. Kirstein C. Luth U. Luth G. Luther L.-A. Meyer-Reil O. Pfannkuche M. Weydert 《Journal of Marine Systems》1994,4(6)
For over thirty years man has studied “outer space” and installed satellites which watch the surface of the Earth. The great depths of the world ocean are, however, practically unknown and there is an urgent need to put abyssal benthic laboratories into “inner space” in order to study basic phenomena of interest to marine science and climatology as well as man's impact on the oceans.In view of the numerous problems related to global change, as a first step emphasis should first be on the role of the oceans and their inherent processes, which are the focus of such international programmes as the World Ocean Circulation Experiment (WOCE) and the Joint Global Ocean Flux Study (JGOFS). Multi-disciplinary registration of key events at selected key sites investigating the variability in time and space are of the utmost importance. The same methods and techniques must be used for the study of human impacts on the deep oceans caused by mining of metalliferous resources and by waste disposal as well as in basic studies. However, the investigation of the inner space of our planet has certain requirements. As long-term and large-scale investigations become more and more important, development of automized systems, largely independent from research vessels will be required. This will demand high capacities of energy for all technical functions as well as high storage capacities for data and samples. As a consequence the needs for two different—although overlapping—functional approaches are defined for future deep-sea deployments.(A) A system for long-term registration of the natural variability and long-term monitoring of human impacts: (B) A system for short-term observations and short-time experimentations. This report summarizes their technological demands. The envisioned interdisciplinary technology should deliver information on physical, biological and geochemical processes and their variabilities in the deep oceans. The prospected systems need to have the ability for real time video observation, data transfer and experimental manipulation, as well as sensing and sampling facilities with large storage capacities for long-term deployments.Prospective costs of the described multipurpose abyssal benthic laboratory will presumably exceed the funds for deep-sea research of a single country. A joint European effort could solve this problem and help to manifest a leading role for European marine science in international deep-sea and global change research. 相似文献
563.
Currentmeter data taken in the Ibiza Channel show the almost permanent presence of near-inertial motions below the mixed layer. They correspond to downwards progressing waves with a vertical group velocity of some m/day. The presence of the Balearic Front sensibly affects the propagation of these inertial waves. Although situations exist in which the passage of atmospheric fronts along the Channel is clearly the generating force of these near-inertial motions we find others in which the energy density in mid-depths is higher than in any other depth. These last situations are closely related to the arrival to the Channel of some of the different water masses which flow around there. A clear correspondence between the presence of relatively strong inertial waves and a noticeable vertical shear of the subinertial flow, evidenced by an averaged Richardson number, is also observed. In some circumstances, the vertical shear of the whole flow (inertial plus subinertial) is higher than the stability limit, that is, Ri < 0.25, favoring the braking of the internal waves. This could be a plausible cause of their decay and a reason to explain why they do not penetrate further than certain depths. 相似文献
564.
A. Stensson C. Asplund L. Karlsson 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1994,23(1):85-106
Three nonlinear models of a MacPherson strut wheel suspension have been studied. The nonlinearities considered are due to the nonlinear geometrical effects in the mechanism, the amplitude limitation due to the bumpstop, the progressive stiffness of the bumpstop and the different damping coefficients for the shock absorber in bump and rebound. The models have been derived according to physical parameter values of. the MacPherson strut wheel suspension of the car SAAB 9.000. The most suitable model was further studied with special attention to nonlinear phenomena. For harmonic forcing the system had phenomena such as multiple solutions and subharmonics. For some parameter values the solution was very sensitive to changes in the integration tolerances in the numerical integration routine. No chaotic steady state solutions were found for the parameter values studied. 相似文献
565.
T. Ciobotaru D. Frunzeti L. Jäntschi 《International Journal of Automotive Technology》2010,11(2):167-172
This paper presents a method for analyzing epicyclic gearboxes by evaluating the speeds, torques and power of the external
elements in epicyclic gear mechanisms, as well as the total ratios of the gear box. The method is based on the equations that
describe each epicyclic gear mechanism and rules that assign appropriate codes to the external elements. The method emphasizes
how power flows are transmitted through the epicyclic gears, as well as power losses. Analysis of an epicyclic gear box is
performed to illustrate the proposed method. 相似文献
566.
R. S. Vieira L. C. Nicolazzi N. Roqueiro 《International Journal of Automotive Technology》2012,13(4):553-562
When considering vehicle safety, tires and all that they represent are a fundamental topic. Tire studies have received a considerable amount of attention from the research community because their improvement has a direct and strong impact on vehicle handling and braking. Within this eld of analysis lies an important behavioral feature: the tire slip angle, which is a consequence of lateral forces acting on the tire. This characteristic is predicted in some cases and evaluated experimentally in others. This paper addresses another way to assess the slip angle. We propose a mathematical model that describes a constraint linking the slip angle and steering angle that make a vehicle turn. We present a simplied kinematic model (based on the classic bicycle model) and a four-wheel model, which makes all of the angles involved compatible with each other. In our case, the match will be given by the determination of the turning radius. Two different scenarios, understeering and oversteering vehicles, were simulated, and the results and conclusions reached are presented herein. 相似文献
567.
Victor F. Ushkalov Michael M. Zhechev A. D. McKisic 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(1):61-76
Three-piece trucks have some drawbacks, particularly unstable operation of the friction wedge damping system. One of the principal features of systems of this kind is the possibility of jamming and wedging. This work is devoted to mathematical and numerical modeling of the plane motion of a freight car with allowance for the mobility of the wedges and then for the compliance of the contacting bodies and to the study of the conditions for the onset of jamming and wedging when the car is in motion. 相似文献
568.
Influences on bicycle use 总被引:2,自引:0,他引:2
A stated preference experiment was performed in Edmonton in Canada to both examine the nature of various influences on bicycle
use and obtain ratios among parameter values to be used in the development of a larger simulation of household travel behaviour.
A total of 1128 questionnaires were completed and returned by current cyclists. Each questionnaire presented a pair of possible
bicycle use alternatives and asked which was preferred for travel to a hypothetical all-day meeting or gathering (business
or social). Alternatives were described by specifying the amounts of time spent on three different types of cycling facility
and whether or not showers and/or secure bicycle parking were available at the destination. Indications of socio-economic
character and levels of experience and comfort regarding cycling were also collected. The observations thus obtained were
used to estimate the parameter values for a range of different utility functions in logit models representing this choice
behaviour. The results indicate, among other things, that time spent cycling in mixed traffic is more onerous than time spent
cycling on bike lanes or bike paths; that secure parking is more important than showers at the destination; and that cycling
times on roadways tend to become less onerous as level of experience increases. Some of these results are novel and others
are consistent with findings regarding bicycle use in work done by others, which is seen to add credence to this work. A review
of previous findings concerning influences on cycling behaviour is also included. 相似文献
569.
台湾唯一之海底隧道系采沉埋方式施工,该隧道不仅处于具高度盐份腐蚀之不利环境,且位于软弱地盘上.于营运二十余年后,轻微异状已有显现,如管段接头锈蚀、管体渗漏及管体裂损等异状.上述异状可能为接头构件变形、管体变位/变形及结构劣化等影响隧道安全之前兆,甚至降低其耐震能力;因该隧道肩负港区及区域经济发展之运输重任,如何藉由整体性体检进行安全评估及研订适当之维护补强对策,为计划执行重点;故本文将说明隧道接头、结构体等隧道重要构件之检测调查(如地球物理、钢筋腐蚀、裂缝深度、氯离子试验、防蚀电位、接头防水等项目)、数值分析及自动化监测(接缝计、单元沉陷仪、结构倾斜仪、电位计等)等综合评估结果及维护补强对策,以提供工程界日后参考. 相似文献
570.
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