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   106篇
  免费   18篇
  国内免费   29篇
航空   46篇
航天技术   38篇
综合类   12篇
航天   57篇
  2023年   1篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2019年   6篇
  2018年   4篇
  2017年   1篇
  2016年   3篇
  2015年   2篇
  2014年   20篇
  2013年   16篇
  2012年   10篇
  2011年   8篇
  2010年   17篇
  2009年   18篇
  2008年   9篇
  2007年   5篇
  2006年   3篇
  2005年   4篇
  2004年   2篇
  2003年   4篇
  2002年   2篇
  2001年   3篇
  2000年   4篇
  1999年   2篇
  1998年   1篇
  1997年   2篇
排序方式: 共有153条查询结果,搜索用时 31 毫秒
31.
载人航天过程中人的可靠性研究   总被引:4,自引:0,他引:4  
周前祥 《上海航天》2001,18(4):26-30
从失误分析、理论研究及可靠性预测三方面详细分析了人的可靠性研究现状 ,在此基础上 ,指出其未来主要的发展方向与手段。最后 ,认为必须从人、机、环境三个方面进行综合考虑来提高航天员的可靠性。  相似文献   
32.
The main objective of a life support system for space missions is to supply a crew with food, water and oxygen, and to eliminate their wastes. The ultimate goal is to achieve the highest degree of closure of the system using controlled processes offering a high level of reliability and flexibility. Enhancement of closure of a biological life support system (BLSS) that includes plants relies on increased regeneration of plant waste, and utilization of solid and liquid human wastes. Clearly, the robustness of a BLSS subjected to stress will be substantially determined by the robustness of the plant components of the phototrophic unit. The aim of the present work was to estimate the heat resistance of two plants (wheat and lettuce) grown on human wastes. Human exometabolites mineralized by hydrogen peroxide in an electromagnetic field were used to make a nutrient solution for the plants. We looked for a possible increase in the heat tolerance of the wheat plants using changes in photosynthetically active radiation (PAR) intensity during heat stress. At age 15 days, plants were subjected to a rise in air temperature (from 23 ± 1 °C to 44 ± 1 °С) under different PAR intensities for 4 h. The status of the photosynthetic apparatus of the plants was assessed by external СО2 gas exchange and fluorescence measurements. The increased irradiance of the plants during the high temperature period demonstrated its protective action for both the photosynthetic apparatus of the leaves and subsequent plant growth and development. The productivity of the plants subjected to temperature changes at 250 W m−2 of PAR did not differ from that of controls, whereas the productivity of the plants subjected to the same heat stress but in darkness was halved.  相似文献   
33.
虚拟人力资源是随着虚拟组织出现和知识经济的兴起而产生的新的人力资源的管理方式。近年来,随着信息技术的进一步升级,虚拟人力资源也出现了新的变化和演进。本文讨论了虚拟人力资源的定义,虚拟人力资源产生的理论背景,并较为完整地梳理了包括众包在内的虚拟人力资源的各种模式。  相似文献   
34.
To estimate astronaut health risk due to space radiation, one must have the ability to calculate various exposure-related quantities that are averaged over specific organs and tissue types. Such calculations require computational models of the ambient space radiation environment, particle transport, nuclear and atomic physics, and the human body. While significant efforts have been made to verify, validate, and quantify the uncertainties associated with many of these models and tools, relatively little work has focused on the uncertainties associated with the representation and utilization of the human phantoms. In this study, we first examine the anatomical properties of the Computerized Anatomical Man (CAM), Computerized Anatomical Female (CAF), Male Adult voXel (MAX), and Female Adult voXel (FAX) models by comparing the masses of various model tissues used to calculate effective dose to the reference values specified by the International Commission on Radiological Protection (ICRP). The MAX and FAX tissue masses are found to be in good agreement with the reference data, while major discrepancies are found between the CAM and CAF tissue masses and the reference data for almost all of the effective dose tissues. We next examine the distribution of target points used with the deterministic transport code HZETRN (High charge (Z) and Energy TRaNsport) to compute mass averaged exposure quantities. A numerical algorithm is presented and used to generate multiple point distributions of varying fidelity for many of the effective dose tissues identified in CAM, CAF, MAX, and FAX. The point distributions are used to compute mass averaged dose equivalent values under both a galactic cosmic ray (GCR) and solar particle event (SPE) environment impinging isotropically on three spherical aluminum shells with areal densities of 0.4 g/cm2, 2.0 g/cm2, and 10.0 g/cm2. The dose equivalent values are examined to identify a recommended set of target points for each of the tissues and to further assess the differences between CAM, CAF, MAX, and FAX. It is concluded that the previously published CAM and CAF point distributions were significantly under-sampled and that the set of point distributions presented here should be adequate for future studies involving CAM, CAF, MAX, or FAX. It is also found that the errors associated with the mass and location of certain tissues in CAM and CAF have a significant impact on the mass averaged dose equivalent values, and it is concluded that MAX and FAX are more accurate than CAM and CAF for space radiation analyses.  相似文献   
35.
36.
This paper proposes a method to predict nonlinear Pilot-Induced Oscillation (PIO) using an intelligent human pilot model. This method is based on a scalogram-based PIO metric, which uses wavelet transforms to analyze the nonlinear characteristics of a time-varying system. The intelligent human pilot model includes three modules: perception module, decision and adaptive module, and execution module. Intelligent and adaptive features, including a neural network receptor, fuzzy decision and adaptation, are also introduced into the human pilot model to describe the behavior of the human pilot accommodating the nonlinear events. Furthermore, an algorithm is proposed to describe the procedure of the PIO prediction method with nonlinear evaluation cases. The prediction results obtained by numerical simulation are compared with the assessments of flight test data to validate the utility of the method. The flight test data were generated in the evaluation of the Smart-Cue/Smart-Gain, which is capable of reducing the PIO tendencies considerably. The results show that the method can be applied to predict the nonlinear PIO events by human pilot model simulation.  相似文献   
37.
人力资源是企业发展动力的源泉,是可持续发展的根本保障。本文根据中国通用航空发展的态势和飞机修理厂的现状与发展目标,对飞机修理厂提出了规划要求和适应发展需要的应对措施。  相似文献   
38.
杨凌职业技术学院与彬县小章镇经过十多年的农科教结合实践,探索出了一条符合西部地区农业技术推广应用及农民教育培训的新方法和新途径,加快了农业科技成果的转化和普及,提高了农民科技文化素质,增加了农民收入,极大地推动了农业科技进步和农村经济发展,实现了学院超常规、跨越式发展。  相似文献   
39.
企业人力资源管理新趋势-人事外包   总被引:3,自引:0,他引:3  
人事外包是人力资源管理的一种新形式 ,企业将事务性传统人力资源管理活动外包出去 ,有利于企业人力资源部专注于战略性人力资源管理。本文阐述了人事外包的内容 ,分析了人事外包给企业创造的管理优势 ,指出企业人事外包必须要有明确的目的 ,并结合企业的实际需要进行  相似文献   
40.
人机工效影响着飞行员操纵飞机的感受,因此在民用飞机设计过程中,对人机工效进行及早考虑是非常重要的。在民用飞机设计的各个阶段,都需要适时邀请具有一定资质的飞行员对驾驶舱的人机工效进行评估。对民用飞机设计中飞控驾驶舱飞行员评估方法进行介绍,对评估的要点进行总结分析,供相关工程设计人员参考。  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