全文获取类型
收费全文 | 255篇 |
免费 | 22篇 |
国内免费 | 16篇 |
专业分类
航空 | 154篇 |
航天技术 | 58篇 |
综合类 | 12篇 |
航天 | 69篇 |
出版年
2024年 | 3篇 |
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 2篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 16篇 |
2011年 | 16篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 15篇 |
2007年 | 23篇 |
2006年 | 20篇 |
2005年 | 24篇 |
2004年 | 18篇 |
2003年 | 15篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有293条查询结果,搜索用时 62 毫秒
281.
一体化的指挥与控制系统(C4ISR)作为网络中心站的核心,在2003年的伊拉克战争中初步展示了其作战能力。信息安全是保证信息获取、信息传输、信息处理和信息使用等多个环节畅通无阻的有力保障。本文综合论述了美军在C4ISR信息安全方面的政策、网络防御及技术应用。 相似文献
282.
本文介绍了目前网络数据库的发展趋势和现况,并提出了访问网络数据库的步骤、方法以及各种方式。如CGI方式、RDA/Web方式、web.sql方式、Cold Fusion方式、Advanced Data Connector方式、Internet Database Connector方式、Active Server Pages与ADO方式、Netscape LiveWire方式、Borland IntraBuilder方式、Novell NetBasic方式等。同时提出了对应的解决方案。 相似文献
283.
A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks. On the basis of traditional multi-path routing, the algorithm uses a random linear network coding strategy to code data pack- ets. Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together. The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding. Meanwhile, the algorithm also adopts the flow distribution strategy based on time delay to balance network load. Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate, reduce packet delay, and enhance network performance. 相似文献
284.
285.
Flight risk prediction is significant in improving the flight crew’s situational awareness because it allows them to adopt appropriate operation strategies to prevent risk expansion caused by abnormal conditions, especially aircraft icing conditions. The flight risk space representing the nonlinear mapping relations between risk degree and the three-dimensional commanded vector(commanded airspeed, commanded bank angle, and commanded vertical velocity) is developed to provide the crew with practi... 相似文献
286.
It is common that airlines encounter a disruption of a flight schedule, which is mainly caused by resource shortages. In case of a disruption, subject to scarce resources, most of airlines lose flexibility of performing aircraft recovery on the basis of business interest priorities and need to delay, swap, and cancel flights. This paper proposes an air-rail inter-modal strategy to incorporate a High-Speed Rail(HSR) transport mode into an aviation network for aircraft recovery. The air-rail inter... 相似文献
287.
针对高分辨率影像地物光谱丰富复杂的问题,文章提出了一种结合像元-对象-空间格局特征的水域、盐田等海岸带精细地物分类方法。首先基于像元和空间格局特征分别利用遗传算法优化随机森林参数进行分类;其次将两种分类结果采用D-S证据理论融合;然后基于不同地物斑块的空间上下文信息,采用粒子群算法优化支持向量机(Support Vector Machine,SVM)参数实现面向对象的二次分类。为验证方法的有效性,收集山东省莱州湾海岸带附近区域的“高分二号”卫星影像,开展了水域及水利设施用地、盐田、工矿用地、交通运输用地、住宅用地、沿海滩涂、海域与耕地8类地物的分类实验,总体精度达到97.21%,Kappa系数为0.964 2。实验结果表明,文章提出的高分影像海岸带地物分类方法兼顾像元、对象及空间格局特征优点,能够实现多层次细致分类,并同时兼具较短的训练时长与较高的分类精度。该研究成果可为中国海岸带生态环境监测与土地利用规划提供一定技术支撑。 相似文献
288.
基于SAN构建高可用实时存储系统 总被引:1,自引:0,他引:1
介绍SAN网络存储技术及其拓扑结构,针对某飞控中心数据存储系统的实际需求,设计和实现一个SAN存储结构上的高可用实时可扩展集群存储方案,并详细描述通过软、硬件结合实现冗余数据路径、故障切换、实时存储和查询的方法。 相似文献
289.
《中国航空学报》2023,36(5):406-420
A reasonable parameter configuration helps improve the data transmission performance of the Licklider Transmission Protocol (LTP). Previous research has focused mainly on parameter optimization for LTP in simplified scenarios with one to two hops or multihop scenarios with a custody mechanism of the Bundle Protocol (BP). However, the research results are not applicable to communications in Complex Deep Space Networks (CDSNs) without the custody mechanism of BP that are more suitable for deep space communications with LTP. In this paper, we propose a model of file delivery time for LTP in CDSNs. Based on the model, we propose a Parameter Optimization Design Algorithm for LTP (LTP-PODA) of configuring reasonable parameters for LTP. The results show that the accuracy of the proposed model is at least 6.47% higher than that of the previously established models based on simple scenarios, and the proposed model is more suitable for CDSNs. Moreover, the LTP parameters are optimized by the LTP-PODA algorithm to obtain an optimization plan. Configuring the optimization plan for LTP improves the protocol transmission performance by at least 18.77% compared with configuring the other parameter configuration plans. 相似文献
290.
Relative measurements are exploited to cooperatively detect and recover faults in the positioning of Mobile Agent(MA) Swarms(MASs). First, a network vertex fault detection method based on edge testing is proposed. For each edge, a property that has a functional relationship with the properties of its two vertices is measured and tested. Based on the edge testing results of the network, the maximum likelihood principle is used to identify the vertex fault sources. Second, an edge distance testing... 相似文献