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981.
We report here on how we adapted Interactive Stated Response Methods to use in a self-completion survey of 454 California households to measure the market for electric vehicles in California. Electric vehicles are a novel product and have many features unfamiliar to consumers, in particular their home recharging capability and limited range. Reflexive techniques were designed to draw households into a deeper exploration of the lifestyle implications of electric vehicles than can be done in more typical self-completion surveys, and to stimulate key decision processes previously observed in detailed gaming interviews with 51 households. Reflexive self-completion techniques provide a middle course between typical large sample quantitative surveys and small sample, detailed gaming interviews. One of the benefits of the more intensive techniques was that participants reported finding the surveys interesting and return rates were high for a self-completion approach – over sixty percent. We review previous transportation and sociological methods which inspired our design, describe the design goals and features of our research, and summarize research results pertinent to testing the validity of our approach. 相似文献
982.
Alan G. Jamieson 《Maritime Policy and Management》1998,25(4):305-312
In the mid 1960s the world OSV industry was dominated by American operators, but with the rise of the North Sea offshore industry, British entrepreneurs were given the chance to contest American dominance. By the mid 1970s British OSV companies had made great progress and, at least in the North Sea context, their principal rivals were now the Norwegians rather than the Americans. British OSV companies continued to prosper until the world oil price collapse of 1986. This blow led to a restructuring of the British OSV industry, which led, by the mid-1990s, to Stirling Shipping being the principal British OSV firm in the North Sea and OIL being the largest non-American OSV company in the world. The 1997 sale of OIL to the Americans was a blow to the British OSV sector, but British enterprise in this field still continues in the North Sea. 相似文献
983.
A probabilistic particle tracking model is used to simulate the oil dispersion after the Prestige wreckage. This oil spill constitutes a suitable benchmark to analyze the capabilities of a probabilistic model, since the time elapsed from wreckage to oil landing (12 days) is much longer than the reliability time associated with forecast winds, usually on the order of 3–4 days. The particle model can be run in two different modes: real time mode (when existing reliable wind fields for the event under scope) and in probabilistic mode (in absence of reliable wind fields but with historical fields corresponding to a similar period). The validity of the particle model is first evaluated in a hindcast way, running the Prestige case with the wind fields corresponding to the period November 19 to November 30, 2002, which were not available at the moment of the wreckage. Calculations show the accuracy of the model to provide the right impact point and timing. The probabilistic model is then used to simulate the same event by means of historical data. The region where the oil landed is shown to be the area with the highest probability to be impacted. 相似文献
984.
高速铁路先简支后连续模型箱梁内模制造及施工工艺探讨 总被引:1,自引:1,他引:0
曹凤洁 《铁道标准设计通讯》2005,(2):39-40
针对高速铁路先简支后连续梁的内模设计、制造及先简支后连续法梁体混凝土灌筑、施工工艺进行探讨。 相似文献
985.
Using the revenues from congestion pricing 总被引:6,自引:0,他引:6
Kenneth A. Small 《Transportation》1992,19(4):359-381
The economic theory behind congestion pricing relies on using the revenues to help compensate highway users. But can practical methods of using revenues come close to achieving this compensation, and still have salient appeal to important political groups? This paper investigates the possibilities for designing a package of revenue uses that can achieve these twin goals. The suggested approach returns two-thirds of the revenues to travelers through travel allowances and tax reductions, and uses the rest to improve transportation throughout the area, including affected business centers. By replacing regressive sales and fuel taxes, this approach offsets the tendency of the prices alone to have a regressive distributional impact. By lowering taxes, funding new highways, improving transit, and upgrading business centers, the package provides inducements for support from several key interest groups. The potential amounts of money involved are discussed using nationwide data, and in more detail using a case study of ubiquitous facility pricing throughout the Los Angeles region. Illustrative calculations of the effects on various individuals confirm that such a package can create net benefits for a wide spectrum of people and interest groups. 相似文献
986.
987.
内破裂的数值模拟与分析 总被引:1,自引:0,他引:1
应用气—波两相流理论,引入计算流体动力学方法中的SIMPLE(Semi—ImplictMethodforPressure-LinkedEquations)方程,并在此基础上进行改进,对压力筒内的内破裂现象进行了系统的研究。本文发展了一套不依赖于试验结果的预报方法,较之以前的理论研究结果有了长足的进展,所采用的模型与假设能用于多种内破裂状况的模拟与预报。本文对一典型的内破状态进行了数值模拟,结合物理现象对模拟结果进行了分析,并与试验作比较。分析结果以一组计算机所绘图形表示,输出结果可作为压力筒结构动力分析的基础,所研制的程序也可作为内破裂问题流—固耦合研究的一大模块。 相似文献
988.
The present procedures for processing arriving passengers at the Colombo International Airport cause inordinte waiting times. An alternate plan, which is based on state of the art customs procedures, and which can reduce waiting times significantly while maintaining a high level of enforcement, is proposed. The present and proposed procedures are analyzed and compared with respect to passenger waiting times, using deterministic queueing theory. An optimal inspection rate of passengers by the customs service is proposed taking into account the fraction of inspected passengers, the waiting time of passengers and the cost of customs processing. 相似文献
989.
介绍了一个运用于摆式车辆的动力学性能仿真的数值计算模型,特别考虑了曲线通过工况。在此模型中,把实车上使用的控制软件和车辆数值计算机械结构模型结合起来,再现了倾摆主动控制装置的动力学。为了验证数值计算仿真模型,把数值计算结果与试验台试验及室外线路试验结果进行了比较。 相似文献
990.
曾克和 《西南交通大学学报》1992,(3):60-66
本文定义了在多项式时间界下不确定图灵纯正多项式归约(记为≤_T~(n p h))的概念,讨论了≤_T~(n p h)极小集的性质、≤_T~(n p h)极小集与≤_T~(p h)极小集的关系。据此,对Homer-Spies猜测提供了一个解答:P=NP当且仅当存在一个集合A,既是≤_T~(p h)极小集,又是≤_T~(n p h)极小集,且deg_T~(p h)(A)=deg_T~(n p h)(A)。 相似文献