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   152篇
  免费   131篇
  国内免费   65篇
航空   207篇
航天技术   51篇
综合类   7篇
航天   83篇
  2024年   1篇
  2023年   6篇
  2022年   18篇
  2021年   19篇
  2020年   22篇
  2019年   16篇
  2018年   6篇
  2017年   9篇
  2016年   14篇
  2015年   10篇
  2014年   13篇
  2013年   20篇
  2012年   13篇
  2011年   20篇
  2010年   21篇
  2009年   13篇
  2008年   11篇
  2007年   12篇
  2006年   12篇
  2005年   6篇
  2004年   8篇
  2003年   11篇
  2002年   6篇
  2001年   2篇
  2000年   6篇
  1999年   6篇
  1998年   6篇
  1997年   4篇
  1996年   5篇
  1995年   7篇
  1994年   6篇
  1993年   2篇
  1992年   6篇
  1991年   2篇
  1990年   4篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
排序方式: 共有348条查询结果,搜索用时 15 毫秒
61.
The aim of this paper is to provide a comprehensive comparison of the thermal insulation and heat transfer performance for Kagome truss-cored lattice along two perpendicular orientations OA and OB. Three test conditions are conducted under forced air convection for the titanium sandwich panel fabricated by 3 D printing technology. The thermo-fluidic characteristics are further explored by numerical simulation to reveal the underlying mechanisms of heat transfer enhancement.The results indicate that the orientation OB exhibits better thermal insulation than orientation OA under the identical temperature loading, while the latter outperforms the former by up to 20% higher overall heat transfer performance. In particular, the endwalls and lattice core in orientation OA achieve 9.7% and 22.5% higher area-averaged Nusselt number respectively than that in orientation OB for a given Reynolds number. The heat transfer superiority of orientation OA comes from the unique topology which induces the large scale spiral primary flows, facilitating the heat exchange between the cooling air and the surfaces of sandwich panel. However, the complex flow mixing leads to a maximum of 20% higher friction factor in orientation OA than that in orientation OB.  相似文献   
62.
马斌捷  吴江  林宏 《强度与环境》2005,32(3):19-23,32
本文依据质点动力学和一维可压缩流体动力学原理,利用无限大容器的出流结果,在适当的简化假设基础上,建立了固体发动机切割分离泄压过程的数学模型,并对泄压过程和分离后的状态变化进行预测.通过比对分析试验容器的理论和试验结果,证明本文方法的误差在15%以内。  相似文献   
63.
介绍了一种以C8051F120单片机为核心设计的低空无人飞艇压力控制系统,详细给出了系统的总体架构;着重说明了主要功能模块的电路设计和固件的程序设计.地面测试和飞行试验表明该压力控制系统性能稳定,能满足低空飞艇飞行中压力控制的要求.  相似文献   
64.
康小录 《上海航天》2000,17(3):37-40
分析了航天器被动检漏的具体要求,对常用几种主要被动检漏方法进行了评述,指出了各种被动检漏方法的优、缺点和技术状态。最后,针对我国航天器的被动检漏需求,推荐了航天器被动检漏的相关措施。  相似文献   
65.
66.
Solar sails change the natural dynamics of systems: Trajectories that are driven by gravitational forces can be displaced and changed because of the effect of Solar Radiation Pressure (SRP). Moreover, if the lightness number of the sail is large enough, the instability of certain orbits can be diminished and even removed. In this paper we modify two models for the motion of a probe in the Earth-Moon system that include the effect of Sun’s gravity to take also into account the effect of SRP. These models, the Bicircular Problem (BCP) and the Quasi-Bicircular Problem (QBCP), are periodic perturbations of the Earth-Moon Restricted Three Body Problem (RTBP). The models are modified to consider the effect of the SRP upon a solar sail. We provide examples of periodic orbits that are stabilized (or made less unstable) due to the effect of SRP.  相似文献   
67.
输油管道泄漏监测技术在实际管道运输中起着举足轻重的作用。为了能够快速准确的检测管道泄漏,定位泄漏点,防止管道泄漏造成经济损失及环境污染,需要对管线泄漏采用适当的办法进行监测。本文介绍了一种基于.NET平台的石油管道泄漏检测系统设计与实现,并对其中关键技术进行了研究与阐述。  相似文献   
68.
介绍了JJG 860-2015《压力传感器(静态)检定规程》的主要变化,就检定设备的选择、特殊压力传感器的检定方法等对规程进行浅析,结合测试实例论述了新增传感器零点漂移和周期稳定性两个性能指标的必要性,并对规程的进一步完善提出了建议。  相似文献   
69.
Measuring ground deformation underwater is essential for understanding Earth processes at many scales. One important example is subduction zones, which can generate devastating earthquakes and tsunamis, and where the most important deformation signal related to plate locking is usually offshore. We present an improved method for making offshore vertical deformation measurements, that involve combining tide gauge and altimetry data. We present data from two offshore sites located on either side of the plate interface at the New Hebrides subduction zone, where the Australian plate subducts beneath the North Fiji basin. These two sites have been equipped with pressure gauges since 1999, to extend an on-land GPS network across the plate interface. The pressure series measured at both sites show that Wusi Bank, located on the over-riding plate, subsides by 11 ± 4 mm/yr with respect to Sabine Bank, which is located on the down-going plate. By combining water depths derived from the on-bottom pressure data with sea surface heights derived from altimetry data, we determine variations of seafloor heights in a global reference frame. Using altimetry data from TOPEX/Poseidon, Jason-1, Jason-2 and Envisat missions, we find that the vertical motion at Sabine Bank is close to zero and that Wusi Bank subsides by at least 3 mm/yr and probably at most 11 mm/yr.  相似文献   
70.
张振家 《推进技术》1988,9(4):21-25,76
本文针对冲压发动机地面试验中存在的不稳定工作现象进行了分析,并对燃烧室压力测量系统特性进行了计算,以判断所得测量结果的真实性.根据冲压发动机的使用特点,文中还提出了燃烧稳定性要求.  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