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401.
In this paper the discrete and dynamic berth allocation problem is formulated as a multi-objective combinatorial optimization problem where vessel service is differentiated upon based on priority agreements. A genetic algorithms based heuristic is developed to solve the resulting problem. A number of numerical experiments showed that the heuristic performed well in solving large, real life instances. The heuristic provided a complete set of solutions that enable terminal operators to evaluate various berth scheduling policies and select the schedule that improves operations and customer satisfaction. The proposed algorithm outperformed a state of the art metaheuristic and provided improved results when compared to the weighted approach.  相似文献   
402.
张宇  朱方伟 《价值工程》2009,28(12):86-89
关键链项目管理方法是约束理论在项目管理中的应用。在对关键链项目管理方法的基本思想和理论基础分析介绍的基础上,针对如何利用关键链将项目计划与项目进度控制更好的结合进行了研究和评价;利用项目管理领域相关知识,补充了缓冲区管理的方法和实施步骤,并运用实例进行了求证。  相似文献   
403.
多工序订单生产排序问题,是一类典型的组合优化问题。采用混合蚁群算法,对一种多工序订单模型进行建模求解,并给出了详细的算法步骤。通过用不同数量的订单、工序组合的数据进行模拟计算与结果比较,证明了混合蚁群算法在求解此类的问题的有效性以及良好的鲁棒性。  相似文献   
404.
The M / G /∞ queue with Optimistic Concurrency Control (OCC) is a model for a special form of parallel transaction processing in a real-time database. Transactions arrive according to a Poisson process and require some generally distributed execution time. One of the differences with ordinary multi- and infinite-server queueing models is that under OCC the successful completion of one transaction may immediately cause the failure of one or more of the other transactions. This happens if the completing transaction has overwritten a data-item that is in use by another transaction in progress. As soon as this failure is detected the failed transaction is restarted. So the total service time of a transaction consists of its final successful run and the time spent on unsuccessful runs.
In this study we develop an approximation for the distribution of the total service time, and test the approximation against simulation. Although in practice the number of servers is never unlimited, this study provides valuable insight in the asymptotics with respect to the number of servers. The approximation clearly demonstrates the very limited performance gain from an increase of the number of servers.  相似文献   
405.
The purpose of this paper is to study and evaluate genetic algorithms and scheduling theory about the methods of controlling public electric transport. Scheduling theory can be defined as criteria of time constraints for target functions of the optimal electric transport control task and for electrical process diagnostics task. Mathematical models and procedures are developed for the control of electrical processes and the optimization of railway traffic control, using scheduling theory and multi-criteria of decision making. Functional dependencies between electrical processes and dynamics of electric transport flow states are investigated in the research. Genetic algorithms are investigated for getting dynamic multi-criteria optimization of processes in real time mode. Efficiency of proposed methods about procedures for optimal electric transport flow control is analyzed and. Safety is considered as an inherent component of the total transport system, which embraces infrastructures, goods and containers, transport users and operators, vehicles and vessels, measures at policy and legislative levels includes decision support and validation tools. Integrated safety and security systems for surface transport systems includes advanced modeling, simulation and engineering tools, aiming at the improvement of safety and security performance of transport systems. Development will include methodologies and designing environments for risk based design and approval, roll-over test development and pre-normative research towards regulations based on virtual testing methods as well as mechatronic systems for dynamic stability, reliable and effective braking systems for vehicles. The paper is based on authors' previous scientific work which researches the intelligent device systems and their applications in transport systems. Intelligent devices are controllers, which have interface to work in global network and wireless networks, and are programmed to use methods of the artificial intelligence. Intelligent devices have possibilities to negotiate with each other and to coordinate their work to get better decision. The results of experiments show the possibility of the developed systems to prevent accidents and to avoid different problems by intelligent diagnostic and coordination devices.  相似文献   
406.
针对LTE业务QoS特征多样化且应考虑业务付费等级的问题,提出了一种改进的比例公平 调度算法。新算法引入不同业务的各QoS指标、付费等级作为参数,并根据各业务的具体QoS 需求在各参数的不同加权配置下切换。仿真结果表明,新算法不但可以极大提高付费业务 的各项QoS指标,还能让所有业务的QoS指标达到既定需求,更好地适应了LTE网络规划的要 求。  相似文献   
407.
讨论了企业订货合同管理中面临的决策问题以及解决途径。应用机器工件调度理论求解包括提前和延期惩罚的合同排序问题,给出了启发式排序规则和求解搜索策略。采用了3种启发式方法:1)接排序规则排序;2)对初始排序施加成对交换技术改善;3)射束搜索技术。实验结果表明,第3种求解质量具有明显优势,能得到令人满意的结果。  相似文献   
408.
Decentralized negotiation: An approach to the distributed planning problem   总被引:3,自引:2,他引:1  
DENEGOT is a distributed planning framework that bases conflict resolution on decentralized peer negotiation. Negotiation is viewed as a distributed search through potential compromises. The framework assumes that a satisficing solution is acceptable (a reasonable assumption in many complex domains). To estimate the quality of potential solutions, the negotiation search space is structured into a lattice of sets of potential compromise solutions based on hard constraints. A solution in a higher set in the lattice, if it is achievable, will be preferable over a solution in a lower set. Agents first search under the hard constraint level representing the highest quality solution standard achievable in the current situation. By relaxing hard constraints, the set of compromises that qualify as a solution are enlarged. Agents search for a resolution under the relaxed hard constraint set when a solution cannot be found under the current set of constraints. The framework consists of three iterative problem-solving phases: coordinated search, negotiation state analysis, and constraint relaxation. The application of the DENEGOT framework to distributed planning problems in two domains is demonstrated.This work was partly supported by the Defense Advanced Research Projects Agency (DARPA), monitored by the Office of Naval Research under contract N00014-89-J-1877, by the Office of Naval Research under a University Research Initiative grant, number N00014-86-K-0764, and by the PRC Independent Research and Development project, number R00911. DPS.  相似文献   
409.
A goal program to select and schedule road projects can include policy considerations in addition to those covered by cost-benefit evaluation. Five economic benefits and twelve environmental, developmental and accessibility objectives constitute the goals in a rural application in Western Australia. A plan and construction schedule can be generated for any set of priorities, each satisfying the budget constraint. Government can choose from them to match current policy concerns and meet the needs of affected residents. The method is particularly valuable when there are linkages between projects.  相似文献   
410.
为满足飞行距离为10~100km、执行航拍和侦察等任务的无人机和地面站之间的数据通信需求,提出了一种低成本、高集成度、多功能及高可靠性的机载数据通信系统方案。设计了S频段收发链路(实现将飞机和各载荷的状态遥测参数下行到地面,并接收地面飞控数据,数据通信码速率达到150 kbit/s)和C频段链路(实现将机载光电吊舱获取的图像信息实时下行到地面接收站,码速率达到10 Mbit/s)。研制的机载数据通信系统质量小于2.0 kg,尺寸为160 mm×139 mm×77 mm;S、C频段下行射频功率均达到7 W时,整机功耗为57.6 W(24 V/2.4 A)。30 kg载重能力的旋翼无人机试飞结果表明,无人机飞行高度超过200 m、飞行距离不超过30 km时,机载数据通信系统完成了机地间可靠的数据通信和实时图像传输任务。  相似文献   
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