全文获取类型
收费全文 | 257篇 |
免费 | 52篇 |
国内免费 | 6篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 14篇 |
2012年 | 18篇 |
2011年 | 11篇 |
2010年 | 24篇 |
2009年 | 22篇 |
2008年 | 26篇 |
2007年 | 23篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 12篇 |
1998年 | 15篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
排序方式: 共有315条查询结果,搜索用时 312 毫秒
81.
针对军事任务计划执行环境中普遍存在的资源不确定性,提出了基于资源缓冲区的军事任务计划预测调度算法。算法首先基于平台有效资源功能向量进行任务—平台分配,分配过程中通过调节平台有效资源功能向量,获得不同的平台资源缓冲区分配方案;然后基于NSGA-Ⅱ算法框架对军事任务计划进行多目标求解,进而获得问题的Pareto最优解集。文章通过仿真算例对算法的可行性和有效性进行验证,实验结果表明,该算法能够有效求解资源不确定军事任务计划问题。 相似文献
82.
用于纯方位目标跟踪的修正极坐标自适应卡尔曼滤波算法 总被引:7,自引:0,他引:7
针对纯方位被动目标跟踪中,直角坐标系下的扩展卡尔曼滤波器容易发散而导致滤波精度很差的问题,提出了一种修正极坐标系下的自适应卡尔曼滤波算法,对虚拟系统噪声进行估计,动态补偿模型线性化误差,对其滤波理论及算法进行了研究和仿真。仿真结果表明,该算法提高了滤波的稳定性、快速性和精确性,优于一般的扩展卡尔曼滤波算法。 相似文献
83.
84.
为实现空中机动单站对运动目标的快速无源定位,提出了一种基于测向交叉定位方法的混合粒子滤波算法.针对粒子滤波初始化存在的问题,该算法从测向交叉定位方法得到建议分布,利用角度测量对状态变量的约束关系产生所需粒子,避免了粒子滤波产生粒子时的随机性,减少了高维情况下所需的粒子数目,降低了运算成本,提高了粒子滤波的实时性能.与粒... 相似文献
85.
It well known that vehicle detection is an important component of the field of object detection. However, the environment of vehicle detection is particularly sophisticated in practical processes. It is compara-tively difficult to detect vehicles of various scales in traffic scene images, because the vehicles partially obscured by green belts, roadblocks or other vehicles, as well as influence of some low illumination weather. In this paper, we present a model based on Faster R-CNN with NAS optimization and feature enrichment to realize the effective detection of multi-scale vehicle targets in traffic scenes. First, we proposed a Retinex-based image adaptive correction algorithm (RIAC) to enhance the traffic images in the dataset to reduce the influence of shadow and illumination, and improve the image quality. Second, in order to improve the feature expression of the backbone network, we conducted Neural Architecture Search (NAS) on the backbone network used for feature extraction of Faster R-CNN to generate the optimal cross-layer connection to extract multi-layer features more effectively. Third, we used the object Feature Enrichment that combines the multi-layer feature information and the context information of the last layer after cross-layer connection to enrich the information of vehicle targets, and improve the robustness of the model for challenging targets such as small scale and severe occlusion. In the imple-mentation of the model, K-means clustering algorithm was used to select the suitable anchor size for our dataset to improve the convergence speed of the model. Our model has been trained and tested on the UN-DETRAC dataset, and the obtained results indicate that our method has art-of-state detection performance. 相似文献
86.
Xing-liang Wu Sen Xu Ai-min Pang Wei-guo Cao Da-bin Liu Xin-yu Zhu Fei-yang Xu Xu Wang 《防务技术》2021,17(4):1262-1268
MgH2, TiH2, and ZrH2 are three typical metal hydrides that have been gradually applied to composite explosives and propellants as additives in recent years. To evaluate ignition sensitivity and explosion severity, the Hartmann device and spherical pressure vessel were used to test ignition energy and ex-plosion pressure, respectively. The results showed that the ignition sensitivity of ZrH2, TiH2 and MgH2 gradually increased. When the concentration of MgH2 is 83.0 g/m3 in Hartmann device, the ignition energy attained a minimum of 10.0 mJ. The explosion pressure of MgH2 were 1.44 times and 1.76 times that of TiH2 and ZrH2, respectively, and the explosion pressure rising rate were 3.97 times and 9.96 times that of TiH2 and ZrH2, respectively, through the spherical pressure vessel. It indicated that the reaction reactivity and reaction rate of MgH2 were higher than that of TiH2 and ZrH2. In addition, to conduct in-depth theoretical analysis of ignition sensitivity and explosion severity, gas production and combus-tion heat per unit mass of ZrH2, TiH2 and MgH2 were tested by mercury manometer and oxygen bomb calorimetry. The experimental results revealed that MgH2 had a relatively high gas production per unit mass (5.15 mL/g), while TiH2 and ZrH2 both had a gas production of less than 2.0 mL/g. Their thermal stability gradually increased, leading to a gradual increase in ignition energy. Furthermore, compared with theoretical combustion heat, the combustion ratio of MgH2, TiH2 and ZrH2 was more than 96.0%, with combustion heat value of 29.96, 20.94 and 12.22 MJ/kg, respectively, which was consistent with the explosion pressure and explosion severity test results. 相似文献
87.
88.
复杂非线性隔冲减振系统计算分析 总被引:1,自引:0,他引:1
基于结构动力学理论,提出了一种用于分析计算复杂非线性隔冲减振系统的双模型两步计算法。该方法将冲击振动分成2个阶段:冲击作用阶段和自由振动阶段。冲击作用阶段,采用两自由度模型进行响应计算,该两自由度模型可有效地解决基础冲击输入问题;自由振动阶段,采用单自由度模型进行响应计算,设备在该阶段以冲击终了时刻的速度和位移为初始条件进行振动。文中还对一个典型的复杂非线性系统的冲击过程进行了数值计算.该方法亦可用于线性隔冲减振系统的计算分析. 相似文献
89.
90.