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   1455篇
  免费   391篇
  国内免费   135篇
  1981篇
  2024年   10篇
  2023年   11篇
  2022年   17篇
  2021年   21篇
  2020年   23篇
  2019年   33篇
  2018年   27篇
  2017年   77篇
  2016年   94篇
  2015年   50篇
  2014年   105篇
  2013年   94篇
  2012年   129篇
  2011年   111篇
  2010年   77篇
  2009年   126篇
  2008年   95篇
  2007年   87篇
  2006年   83篇
  2005年   89篇
  2004年   87篇
  2003年   71篇
  2002年   64篇
  2001年   55篇
  2000年   50篇
  1999年   40篇
  1998年   36篇
  1997年   41篇
  1996年   31篇
  1995年   25篇
  1994年   31篇
  1993年   28篇
  1992年   21篇
  1991年   26篇
  1990年   7篇
  1989年   3篇
  1988年   4篇
  1987年   2篇
排序方式: 共有1981条查询结果,搜索用时 15 毫秒
891.
为了延长车载惯性平台的使用寿命并提高其稳定精度,在原有平台机械结构的基础上,提出采用光纤陀螺代替原有的挠性陀螺作为惯性平台的敏感元件,并重新建立了平台系统稳定回路的数学模型。仿真研究表明该数字稳定回路具有较好的动态和稳态性能,能够满足系统的设计要求。经实验验证,该光纤陀螺惯性平台系统已实现功能要求。  相似文献   
892.
893.
We consider an expansion planning problem for Waste‐to‐Energy (WtE) systems facing uncertainty in future waste supplies. The WtE expansion plans are regarded as strategic, long term decisions, while the waste distribution and treatment are medium to short term operational decisions which can adapt to the actual waste collected. We propose a prediction set uncertainty model which integrates a set of waste generation forecasts and is constructed based on user‐specified levels of forecasting errors. Next, we use the prediction sets for WtE expansion scenario analysis. More specifically, for a given WtE expansion plan, the guaranteed net present value (NPV) is evaluated by computing an extreme value forecast trajectory of future waste generation from the prediction set that minimizes the maximum NPV of the WtE project. This problem is essentially a multiple stage min‐max dynamic optimization problem. By exploiting the structure of the WtE problem, we show this is equivalent to a simpler min‐max optimization problem, which can be further transformed into a single mixed‐integer linear program. Furthermore, we extend the model to optimize the guaranteed NPV by searching over the set of all feasible expansion scenarios, and show that this can be solved by an exact cutting plane approach. We also propose a heuristic based on a constant proportion distribution rule for the WtE expansion optimization model, which reduces the problem into a moderate size mixed‐integer program. Finally, our computational studies demonstrate that our proposed expansion model solutions are very stable and competitive in performance compared to scenario tree approaches. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 47–70, 2016  相似文献   
894.
This viewpoint takes stock of the changes in the strategic nuclear landscape in recent decades and reflects on its consequences on the policy community. It finds that the number and scope of issues have expanded considerably; they have manifested themselves in many more regions of the world; and they have become deeply politicized and polarized. The consequences have been twofold: the nuclear policy field has seen the development of an increasingly diverse expert community composed of highly specialized functionalists and regionalists, and it has become ever more divided into two entirely separate ideological camps—one that believes in deterrence, the other in disarmament. The stove-piping of expertise and the widening gap between deterrence and disarmament ideologies are immensely problematic because, in different ways, they stand in the way of the emergence of a better and safer nuclear future. Looking ahead, it is critical to “bust the silos of expertise” and to build bridges between the deterrence and disarmament ideological camps. Only such a community-building effort will help solve today’s and tomorrow’s nuclear challenges.  相似文献   
895.
Military interest in incapacitating biochemical weapons has grown in recent years as advances in science and technology have appeared to offer the promise of new “non-lethal” weapons useful for a variety of politically and militarily challenging situations. There is, in fact, a long and unfulfilled history of attempts to develop such weapons. It is clear that advances are opening up a range of possibilities for future biological and chemical weapons more generally. The treaties prohibiting biological and chemical weapons make no distinction between lethal and “non-lethal” weapons—all are equally prohibited. Indeed, a sharp and technically meaningful distinction between lethal and “non-lethal” biological and chemical weapons is beyond the capability of science to make. Thus, interest in incapacitating biochemical weapons, and efforts on the part of various states to develop them, pose a significant challenge to the treaty regimes, to the norms against biological and chemical warfare that they embody, and, ultimately, to the essential protections that they provide. Preventing a new generation of biological and chemical weapons from emerging will take concerted efforts and action at the local, national, and international levels.  相似文献   
896.
文中主要对一体化联合作战中的精确控制内涵进行了阐述,然后分别从重要性和实现途径两个方面对作战时序的精确控制、作战空间的精确控制、作战目标的精确控制和作战信息环境的精确控制进行探讨。  相似文献   
897.
国内控制系统故障诊断技术的现状与展望   总被引:12,自引:0,他引:12  
介绍了国内控制系统故障诊断技术的发展情况,对其各种方法进行了详细的评述,给出其应用总结,最后对其发展进行了展望。  相似文献   
898.
防空导弹垂直发射转弯优化设计的新方法   总被引:3,自引:0,他引:3  
防空导弹采用垂直发射方式时 ,最重要的要求就是导弹发射后在最短的时间内以最小转弯半径完成程序转弯 ,所以是一个快速最优控制问题 ,文章对连续系统的最优控制进行离散化 ,从而应用遗传算法对防空导弹垂直发射转弯程序进行了优化设计  相似文献   
899.
论述了指挥与控制系统面向决策的重要性和必要性,并在工程实践的基础上,对指挥与控制系统的决策、决策过程与结构、系统设计与系统评估等方面的主要问题作了进一步阐述与探讨。  相似文献   
900.
对固定形式的变结构控制对应的趋近律进行了研究,分别推导出用全部状态构成的控制、用部分状态构成的控制以及形式为u=ueq+ud的控制所对应的趋近律.  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