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   937篇
  免费   279篇
  国内免费   23篇
  1239篇
  2022年   6篇
  2021年   48篇
  2020年   8篇
  2019年   5篇
  2018年   5篇
  2017年   10篇
  2016年   7篇
  2015年   29篇
  2014年   39篇
  2013年   32篇
  2012年   20篇
  2011年   16篇
  2010年   50篇
  2009年   70篇
  2008年   42篇
  2007年   66篇
  2006年   29篇
  2005年   35篇
  2004年   7篇
  2003年   2篇
  2002年   6篇
  2001年   10篇
  2000年   22篇
  1999年   125篇
  1998年   88篇
  1997年   74篇
  1996年   63篇
  1995年   51篇
  1994年   48篇
  1993年   39篇
  1992年   42篇
  1991年   38篇
  1990年   47篇
  1989年   10篇
  1988年   5篇
  1987年   13篇
  1986年   8篇
  1985年   9篇
  1983年   11篇
  1982年   3篇
  1978年   1篇
排序方式: 共有1239条查询结果,搜索用时 15 毫秒
821.
CALS工作与企业信息化紧密联系。本文分析了信息化相对落后企业的现状及原因,对企业如何开展CALS工作提出了具体做法,并就应重点处理的问题进行了阐述。  相似文献   
822.
临近空间飞行器应用前景及发展分析   总被引:5,自引:0,他引:5  
王艳奎 《国防科技》2009,30(2):20-24
文章以临近空间飞行器的应用前景及发展趋势为背景,综合近来国外的研究发展状况,介绍了临近空间飞行器的优势、军事应用,美国对临近空间飞行器的理解及发展目标和技术途径,并结合临近空间飞行器的发展趋势和我国的发展提出了建议。  相似文献   
823.
In this paper we study the scheduling problem that considers both production and job delivery at the same time with machine availability considerations. Only one vehicle is available to deliver jobs in a fixed transportation time to a distribution center. The vehicle can load at most K jobs as a delivery batch in one shipment due to the vehicle capacity constraint. The objective is to minimize the arrival time of the last delivery batch to the distribution center. Since machines may not always be available over the production period in real life due to preventive maintenance, we incorporate machine availability into the models. Three scenarios of the problem are studied. For the problem in which the jobs are processed on a single machine and the jobs interrupted by the unavailable machine interval are resumable, we provide a polynomial algorithm to solve the problem optimally. For the problem in which the jobs are processed on a single machine and the interrupted jobs are nonresumable, we first show that the problem is NP‐hard. We then propose a heuristic with a worst‐case error bound of 1/2 and show that the bound is tight. For the problem in which the jobs are processed on either one of two parallel machines, where only one machine has an unavailable interval and the interrupted jobs are resumable, we propose a heuristic with a worst‐case error bound of 2/3. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007  相似文献   
824.
本文针对我军现装备手榴弹存在的性能偏低、安全性不高等问题,分析了手榴弹的发展趋势和未来展望,提出了尽快研发具有碰炸/延时双作用全保险型多功能引信的手榴弹的建议。  相似文献   
825.
Plug‐in hybrid electric vehicles (PHEVs), upon market penetration, will create additional recharging loads to the electric power systems. This article considers different recharging scenarios and uses game theoretic models to study the potential impact of the recharging loads on locational marginal prices (wholesale electricity prices). Computational results from a Pennsylvania‐New Jersey‐Maryland Interconnection case study show that, under the existing recharging infrastructures, even a small magnitude of load increase caused by PHEV recharging could have a significant undesirable impact on locational marginal prices. The impact could be mitigated to a varying extent by the availability of possible future recharging infrastructures, including realtime pricing recharging meters, battery stations, or vehicle‐to‐grid technology.© 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010  相似文献   
826.
电磁兼容性设计是机动式指挥自动化系统的重要环节。电磁屏蔽、滤波、接地等技术是电磁兼容性设计的重要方法。电磁屏蔽是抑制辐射干扰的一种有效隔离方法。滤波是抑制传导干扰最直接、最有效的方法,对于瞬态脉冲干扰,最有效的办法是采用脉冲吸收技术。接地的综合考虑,对产品电磁兼容性有至关重要的意义。针对机动式指挥自动化系统的结构和组成特点,给出了一些具体的电磁干扰抑制设计,对满足实际的电磁兼容性方面作出了有意义的尝试。  相似文献   
827.
Supply chain members can gain substantial benefits by coordinating their activities. However, a remaining challenge is to create useful coordination mechanisms when channel members are independent. This paper develops a coordination strategy with which a supplier uses quantity discounts to entice independent buyers to comply with an integer‐ratio time coordination scheme. The problem is analyzed as a Stackelberg game in which the supplier acts as the leader by announcing its coordination policy in advance and buyers act as followers by deciding their ordering decisions with this information. The strategy is compared to a coordination mechanism with quantity discounts and power‐of‐two time coordination. While both strategies are able to produce substantial benefits over simple quantity discounts, integer‐ratio time coordination provides a better coordination mechanism for a decentralized supply chain. It is shown that power‐of‐two time coordination may not be able to provide a stable equilibrium coordination strategy when buyers act independently and opportunistically. Furthermore, if this is not the case, integer‐ratio time coordination is at least equally effective. Unlike a centralized solution, under which the improvement by integer‐ratio over power‐of‐two time coordination is limited to 2% of optimality, system cost reduction from a decentralized coordination strategy could be much more significant. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004.  相似文献   
828.
本文从中美经济政治关系的产生、发展及蜕变与两国军事关系的萌芽,美国门户开放政策的军事含义及其对中美军事关系的深远影响,日本在远东及太平洋的侵略扩张与中美军事战略关系正式形成等三个方面,对中美军事战略关系在特定阶段的表现形式及特点进行了分析探讨。  相似文献   
829.
隐身涂料的研究及发展现状   总被引:2,自引:0,他引:2  
综述了隐身涂料的分类、研究及发展现状,包括可见光隐身涂料,红外隐身涂料,激光隐身涂料、雷迭隐身涂料,声呐隐身涂料和多功能隐身涂料等。  相似文献   
830.
本文论述了利用计算机图形学的原理绘制平面连杆机构连杆曲线的技术及优越性,并给出绘制两自由度五杆机构连杆曲线的实例。按文中所述方法可类似地对其他多杆机构连杆曲线进行绘制。  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