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   172篇
  免费   63篇
  国内免费   5篇
  2021年   10篇
  2020年   1篇
  2017年   2篇
  2015年   7篇
  2014年   4篇
  2013年   4篇
  2012年   1篇
  2011年   1篇
  2010年   12篇
  2009年   10篇
  2008年   8篇
  2007年   22篇
  2006年   3篇
  2005年   8篇
  2004年   2篇
  2003年   1篇
  2001年   2篇
  2000年   7篇
  1999年   19篇
  1998年   20篇
  1997年   18篇
  1996年   14篇
  1995年   9篇
  1994年   8篇
  1993年   12篇
  1992年   8篇
  1991年   5篇
  1990年   7篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1985年   3篇
  1983年   5篇
  1982年   1篇
排序方式: 共有240条查询结果,搜索用时 0 毫秒
131.
本文力图从能表征状态的热力学参数熵的变化中找到有关有限时间热力学新的分析方法,提出了工作参数选择的最小熵产生最大值原则。这个原则揭示了有限时间热力学以时间为基础的“率”与非平衡热力学熵产生间的内在联系。据此,我们便可得到正、反向内可逆卡诺循环的最佳工作参数。为有限时间热力学的普遍应用研究提供了一新的线索。  相似文献   
132.
本文介绍了双基地系统收站自主的定位原理及跟踪算法WMEKF (WeightedModified Extended Kalman Filter),提出了一种对机动目标的自适应跟踪算法AWMEKF(Adaptive WMEKF),并对典型的机动目标航迹进行了计算机仿真。  相似文献   
133.
In this study, the anti-penetration performance of polyurea/ASTM1405-steel composite plate subjected to high velocity projectile was analyzed. Two kinds of modified polyurea material (AMMT-053 and AMMT-055) were selected and a ballistic impact testing system including speed measuring target system and high-speed camera was designed. This experiment was conducted with a rifle and 5.8 mm projectile to explore the effects by the polyurea coating thickness, the polyurea coating position and the glass-fiber cloth on the anti-penetration performance of polyurea/ASTM1405-steel composite plate. The result showed that the effects of polyurea coating position were different between two types of polyurea, and that the effects of glass-fiber position were disparate between two types of polyurea as well. For AMMT-053 polyurea material, it was better to be on front face than on rear face; whereas for AMMT-055 pol-yurea, it was better to be on rear surface although the difference was very subtle. Additionally, formulas had been given to describe the relationship between the effectiveness of polyurea and the thickness of polyurea coating. In general, AMMT-055 had better anti-penetration performance than AMMT-053. Furthermore, five typical damage modes including self-healing, crack, local bulge, spallation and local fragmentation were defined and the failure mechanism was analyzed with the results of SHPB test. Additionally, the bonding strength played an important role in the anti-penetration performance of polyurea/steel composite plate.  相似文献   
134.
An economic two-stage screening procedure based on a dichotomous performance variable T and a continuous screening variable X is proposed. X is measured first to decide whether an item should be accepted, rejected, or additional observations should be taken. If no terminal decision is reached, T is then observed to classify the undecided items. Two models are considered; (i) the logistic model, where P(T = 1|X = x) is assumed to be a logistic function of x, and (ii) the normal model, where X given T is assumed to be normally distributed. A simple economic model based on inspection and misclassification costs is constructed. Optimal cutoff values on the screening variable are obtained by minimizing the expected cost subject to the constraint that the average outgoing quality attains a pre-specified level. Solutions are provided for both known-parameter and unknown-parameter cases. © 1995 John Wiley & Sons, Inc.  相似文献   
135.
GM(1,1)模型与指数回归模型的比较与研究   总被引:3,自引:0,他引:3  
GM(1,1)模型与指数回归模型都是对具有指数或近似指数规律的系列数据建立的数学模型。通过对两种模型进行比较与研究,发现一方面,利用数据列的灰指数特性建立指数回归模型,可以简单地实现数据列的预测过程;另一方面,利用指数回归模型可以对灰色理论的GM(1,1)模型进行控制和优化。  相似文献   
136.
首先提出了视情工作间隔时间的确定方法,然后根据故障率的不同情况,分析了间隔时间的相应变化,最后进行了实际应用方面的讨论.  相似文献   
137.
Economic screening procedures based on a continuous screening variable X in place of a dichotomous performance variable T are presented. Optimal critical values on the screening variable minimizing the expected cost are obtained for two models; it is assumed that X given T is normally distributed in normal model and P[T = 1|X] is a logistic function of X in the logistic model, and that costs are incurred by screening inspection and misclassification errors. Cases where some parameters are unknown are also considered.  相似文献   
138.
本文论述了红军长征中左右两路军北上过程中的指挥系统、指挥班子、通讯系统、通讯队伍及其左右两路军的关系等重要问题。  相似文献   
139.
140.
随着武警部队三级综合通信网络的不断完善和功能拓展,基层执勤部队信息化人才的选拔培养和使用管理效益,已成为影响和制约信息化平台功能有效发挥的重要因素。  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