首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   235篇
  免费   83篇
  国内免费   9篇
  327篇
  2023年   2篇
  2022年   5篇
  2021年   11篇
  2020年   12篇
  2019年   6篇
  2018年   8篇
  2017年   9篇
  2016年   5篇
  2015年   16篇
  2014年   10篇
  2013年   19篇
  2012年   27篇
  2011年   12篇
  2010年   19篇
  2009年   13篇
  2008年   7篇
  2007年   11篇
  2006年   7篇
  2005年   9篇
  2004年   19篇
  2003年   9篇
  2002年   20篇
  2001年   17篇
  2000年   6篇
  1999年   8篇
  1998年   4篇
  1997年   9篇
  1996年   7篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1990年   7篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1983年   2篇
  1982年   2篇
排序方式: 共有327条查询结果,搜索用时 15 毫秒
291.
为了研究残余电压对连发型脉冲功率电源的影响,分析了混合储能型脉冲功率电源的充放电过程及残余电压的来源及其对连续充放电过程的影响,并进行了仿真。仿真结果表明:混合储能型脉冲功率电源可以合理利用残余电压,从而缩短脉冲功率电源的充放电时间,有利于提高电磁发射装置的连发频率,通过能量回收还有利于提高发射效率。  相似文献   
292.
研究了在雷达存在系统误差情况下的航迹关联问题,分析了时变系统误差对航迹形成的影响,将系统时变误差的影响用灰区域来描述。提出了一种基于区域覆盖度的航迹关联算法,研究了算法在不同条件下的适用性,并将该算法拓展应用到异步等速率情况下,带有时间误差和系统误差直接进行关联,仿真结果显示关联正确率较高。  相似文献   
293.
294.
Trade-in programs have been widely adopted to enhance repeat purchase from replacement customers. Considering that a market consists of replacement and new segments, we study the joint and dynamic decisions on the selling price of new product (hereafter, “selling price”) and the trade-in price involved in the program. By adopting a vertical product differentiation choice model, we investigate two scenarios in this paper. In the base model, the manufacturer has sufficiently large production capacity to fulfill the customer demand. We characterize the structural properties of the joint pricing decisions and compare them with the optimal pricing policy under regular selling. We further propose a semi-dynamic trade-in program, under which the new product is sold at a fixed price and the trade-in price can be adjusted dynamically. Numerical experiments are conducted to evaluate the performance of the dynamic and semi-dynamic trade-in programs. In an extended model, we consider the scenario in which the manufacturer stocks a batch of new products in the beginning of the selling horizon and the inventory cannot be replenished. Following a revenue management framework, we characterize the structural properties with respect to time period and inventory level of new products.  相似文献   
295.
We consider a design problem for wastewater treatment systems that considers uncertainty in pollutant concentration levels at water sources. The goal is to optimize the selection of treatment technologies and pipeline connections, so that treated wastewater can achieve specified effluents discharge limits as well as possible. We propose a new two-stage model to optimize a set of guarantee levels, that is, the maximum concentration level of source pollutants for which treated wastewater can be compliant with discharge limits. In the first stage, treatment technologies and pipeline connections are selected. In the second stage, when pollutant concentration levels are revealed, wastewater distribution and mixing are determined. A key attractiveness of the proposed guarantee rate optimization model is that it can be simplified into a single-stage mixed-integer linear program. In our numerical experiments based on real-world pollutants data, the guarantee rate model demonstrates its advantages in terms of computational efficiency, scalability and solution quality, compared with the standard probability maximization model. Finally, the methodology proposed in this paper can also be applied to other two-stage problems under uncertainty with similar uncertainty characteristics.  相似文献   
296.
In many applications, managers face the problem of replenishing and selling products during a finite time horizon. We investigate the problem of making dynamic and joint decisions on product replenishment and selling in order to improve profit. We consider a backlog scenario in which penalty cost (resulting from fulfillment delay) and accommodation cost (resulting from shortage at the end of the selling horizon) are incurred. Based on continuous‐time and discrete‐state dynamic programming, we study the optimal joint decisions and characterize their structural properties. We establish an upper bound for the optimal expected profit and develop a fluid policy by resorting to the deterministic version of the problem (ie, the fluid problem). The fluid policy is shown to be asymptotically optimal for the original stochastic problem when the problem size is sufficiently large. The static nature of the fluid policy and its lack of flexibility in matching supply with demand motivate us to develop a “target‐inventory” heuristic, which is shown, numerically, to be a significant improvement over the fluid policy. Scenarios with discrete feasible sets and lost‐sales are also discussed in this article.  相似文献   
297.
自行高炮数字随动系统原理及检测仪设计思想   总被引:1,自引:0,他引:1  
某型自行高炮数字式随动系统结构复杂,包括数字控制器、模拟控制电路、电机及控制装置等.对某型自行高炮的数字式随动系统原理和结构进行了分析,从故障定位最小可更换单元、在线检测等角度入手,提出了该型随动系统检测仪的基本设计思想.  相似文献   
298.
消费者对居住环境除了继续要求不断扩大“生活空间”外,更要求高品位的文化环境。提高居住环境的质量、营造自然和人文和谐的生态文化、提升居住文化环境的质量和品位,使人居活动与社会活动、文化活动、生态活动完美地结合在一起,无疑将成为现代居住环境建设的一大亮点。  相似文献   
299.
为了研究反辐射导弹(ARM)对雷达阵地连续攻击时的作战效能,提出采用马尔可夫链进行分析.该方法是在单发反辐射导弹对雷达的毁伤概率基础上,依据ARM连续攻击时阵地中雷达工作状态的变化,得到了ARM对雷达阵地的毁伤概率数学模型.同时,运用马尔可夫链的性质对所建立的模型进行了深入分析,并通过实例检验了该模型的有效性.  相似文献   
300.
按照装备保障建设的客观要求,从加强企业引导、军地信息融合、推行合同保障、实现技术融合等方面对军民一体化装备保障体系的构建进行了探讨,对整合和利用军地装备保障资源,加强军民一体化装备保障建设具有重要的现实意义。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号