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981.
982.
Two new constructions of chosen-ciphertext secure fuzzy identity-based encryption(fuzzy-IBE) schemes without random oracle are proposed.The first scheme combines the modification of chosen-plaintext secure Sahai and Waters'"large universe"construction and authenticated symmetric encryption, and uses consistency checking to handle with ill-formed ciphertexts to achieve chosen-ciphertext security in the selective ID model.The second scheme improves the effciency of first scheme by eliminating consistency checking.This improved scheme is more effcient than existing chosen-ciphertext secure fuzzy-IBE scheme in the standard model. 相似文献
983.
Reflections on energy issues in China 总被引:2,自引:0,他引:2
江泽民 《上海交通大学学报(英文版)》2008,13(3):257-274
Energy, which has a bearing on both economic and national security, is of importance and a major constraining factor to the economic and social development of China. The article analyses the current worldenergy status and development trend from the perspectives of resources, production and consumption and in thecontext of its implications on the environment and economic and social development, and explores opportunitiesand challenges for China's energy development. With a focus on the strategy of energy development in China,the author proposes a new energy development approach with Chinese characteristics whose main elementsare: energy-saving, high-efficiency, diversified development, environment protection, technology guidance andinternational cooperation. In other words, China is striving to build a reliable energy production, circulationand consumption system that is efficient, technologically advanced, low polluting and ecologically friendly. Along-term development strategy with priority on energy conservation, efficient utilization of primary energyand advanced electricity system is expounded in the paper. The author also describes the prospect of energytechnology development and stresses the implementation of energy strategy by further improving energy policyand related mechanisms, strengthening macro-management and the essential role of the market in resourceallocation so as to ensure the economic and social development of China through reliable energy supply. 相似文献
984.
ABSTRACTBased on the increasing demands of transportation development, the concept of an Intelligent Transportation System (ITS) has received increasing attention in both academic and industry arenas. It integrates information, communications, computers and other technologies, and applies them in the field of transportation to build an integrated system of people, roads and vehicles by utilizing advanced data communication technologies. It can establish a large, fully functioning, real-time, accurate and efficient transportation management system. Intelligent transportation systems shift the focus from road managers to road users. In order to achieve this purpose, intelligent transportation systems use advanced technology to provide drivers with convenient information to help reduce traffic congestion and to increase available road capacity. This special issue is dedicated to exploring the most recent advances in intelligent transportation systems and big data based on intelligent technology. 相似文献
985.
Research on using high-resolution event-based data for traffic modeling and control is still at early stage. In this paper, we provide a comprehensive overview on what has been achieved and also think ahead on what can be achieved in the future. It is our opinion that using high-resolution event data, instead of conventional aggregate data, could bring significant improvements to current research and practices in traffic engineering. Event data records the times when a vehicle arrives at and departs from a vehicle detector. From that, individual vehicle’s on-detector-time and time gap between two consecutive vehicles can be derived. Such detailed information is of great importance for traffic modeling and control. As reviewed in this paper, current research has demonstrated that event data are extremely helpful in the fields of detector error diagnosis, vehicle classification, freeway travel time estimation, arterial performance measure, signal control optimization, traffic safety, traffic flow theory, and environmental studies. In addition, the cost of event data collection is low compared to other data collection techniques since event data can be directly collected from existing controller cabinet without any changes on the infrastructure, and can be continuously collected in 24/7 mode. This brings many research opportunities as suggested in the paper. 相似文献
986.
Rail network velocity is defined as system-wide average speed of line-haul movement between terminals. To accommodate increased service demand and load on rail networks, increase in network velocity, without compromising safety, is required. Among many determinants of overall network velocity, a key driver is service interruption, including lowered operating speed due to track/train condition and delays caused by derailments. Railroads have put significant infrastructure and inspection programs in place to avoid service interruptions. One of the key measures is an extensive network of wayside mechanical condition detectors (temperature, strain, vision, infrared, weight, impact, etc.) that monitor the rolling-stock as it passes by. The detectors are designed to alert for conditions that either violate regulations set by governmental rail safety agencies or deteriorating rolling-stock conditions as determined by the railroad.Using huge volumes of historical detector data, in combination with failure data, maintenance action data, inspection schedule data, train type data and weather data, we are exploring several analytical approaches including, correlation analysis, causal analysis, time series analysis and machine learning techniques to automatically learn rules and build failure prediction models. These models will be applied against both historical and real-time data to predict conditions leading to failure in the future, thus avoiding service interruptions and increasing network velocity. Additionally, the analytics and models can also be used for detecting root cause of several failure modes and wear rate of components, which, while do not directly address network velocity, can be proactively used by maintenance organizations to optimize trade-offs related to maintenance schedule, costs and shop capacity. As part of our effort, we explore several avenues to machine learning techniques including distributed learning and hierarchical analytical approaches. 相似文献
987.
对深水碎石整平系统进行介绍,分析了整平系统的核心装备——抛石整平头的各项性能,并给出了对应的定性与定量的分析。介绍了整平系统位于半潜驳上的刮平试验情况,对试验数据进行了分析。此试验采用西门子PLC,集合以太网通讯技术,采集GPS高程参数,采用位置算法,集成了防超差功能,对抛石头油缸进行了自动同步精度控制。试验结果表明抛石系统满足设计要求,该系统的分析可为此类工程系统的设计与制作提供参考。 相似文献
988.
This paper proposes a new spatial multivariate count model to jointly analyze the traffic crash-related counts of pedestrians and bicyclists by injury severity. The modeling framework is applied to predict injury counts at a Census tract level, based on crash data from Manhattan, New York. The results highlight the need to use a multivariate modeling system for the analysis of injury counts by road-user type and injury severity level, while also accommodating spatial dependence effects in injury counts. 相似文献
989.
基于公交客运走廊划分的交通小区,可为走廊公交线网优化提供更为符合公交乘客出行特征的需求分析和预测基础.本研究针对公交客运走廊特点,将走廊划分为直接影响区和间接影响区,提出分层次的交通小区划分理论.针对走廊不同影响区在需求预测和分析中对结果精度要求的不同,基于大数据选取更加适合公交走廊交通小区划分的聚类指标,提出直接影响区细分和间接影响区合并的划分方法,并通过引入聚类因子初步确定聚类数目和交通小区中心对传统聚类方法进行改进,克服了传统聚类方法随机选取聚类数目和中心而影响聚类精度的不足.最后,基于多源异构大数据对广渠路走廊进行实例验证,结果表明,本研究提出的分层次小区划分方法较传统方法在适用于公交客运走廊需求分析和预测划分精度方面更优. 相似文献
990.
针对无接触网有轨电车设计了一套基于大数据分析技术及物联网技术的车地无线传输系统。介绍了该系统的系统架构、系统功能及设计要点。该系统能够显著提升列车车地数据传输的安全性、高效性及便捷性,提高了无接触网有轨电车车地传输技术和智能化应用水平。同时,该系统具有良好的可扩展性,可满足各类城市轨道交通车辆车载设备调试、维护以及数据传输的应用需求。 相似文献