全文获取类型
收费全文 | 671篇 |
免费 | 98篇 |
国内免费 | 214篇 |
专业分类
航空 | 651篇 |
航天技术 | 137篇 |
综合类 | 117篇 |
航天 | 78篇 |
出版年
2024年 | 4篇 |
2023年 | 12篇 |
2022年 | 26篇 |
2021年 | 39篇 |
2020年 | 37篇 |
2019年 | 42篇 |
2018年 | 30篇 |
2017年 | 36篇 |
2016年 | 41篇 |
2015年 | 49篇 |
2014年 | 41篇 |
2013年 | 44篇 |
2012年 | 42篇 |
2011年 | 66篇 |
2010年 | 43篇 |
2009年 | 42篇 |
2008年 | 30篇 |
2007年 | 36篇 |
2006年 | 35篇 |
2005年 | 30篇 |
2004年 | 19篇 |
2003年 | 19篇 |
2002年 | 24篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 17篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 17篇 |
1992年 | 21篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1986年 | 2篇 |
排序方式: 共有983条查询结果,搜索用时 0 毫秒
981.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(3):1418-1435
Land use and cover change (LUCC) is one of the key variables dominating land–atmosphere interactions and strongly affects the Earth’s eco-environments by altering surface properties. Numerous studies have been carried out to assess the impact of LUCC. However, the Earth is a large, open and complex system characterized by complex interactions between its eco-environments and drivers. This study aimed to summarize previous studies of the impact of LUCC on the Earth’s eco-environments and discuss the progress and limitations in suggesting future directions. Previous studies have confirmed that LUCC has a wide range of impacts on the Earth’s eco-environments, which are represented by the alternation of climate (temperature, precipitation, wind, and humidity), hydrology (soil moisture, runoff, and evapotranspiration), ecology and environmental (air, water, and soil) pollution. Physically, the impacts were mainly attributed to the disturbance of the surface radiation budget and matter conservation caused by LUCC. Although great achievements have been made, several challenges remain because of the unavoidable uncertainties in data sources and methodologies and the complexity of eco-environmental evolution. Therefore, data assimilation, physical-based investigations, contribution isolation, and full-process analysis are required to overcome these challenges in future research. The results of this study helped to capture the impact of LUCC and its physical mechanisms, which provide useful clues for future research and support the relative land use management for sustainable development. 相似文献
982.
A Robotic TeleoperationSystem for Precise Robotic Manipulation by Human-Machine Interaction
下载免费PDF全文
![点击此处可从《上海航天》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Teleoperation is of great importance in the area of robotics, especially when people are unavailable in the robot workshop. It provides a way for people to control robots remotely using human intelligence. In this paper, a robotic teleoperation system for precise robotic manipulation is established. The data glove and the 7-degrees of freedom (DOFs) force feedback controller are used for the remote control interaction. The control system and the monitor system are designed for the remote precise manipulation. The monitor system contains an image acquisition system and a human-machine interaction module, and aims to simulate and detect the robot running state. Besides,a visual object tracking algorithm is developed to estimate the states of the dynamic system from noisy observations. The established robotic teleoperation systemis applied to a series of experiments, and high-precision results are obtained, showing the effectiveness of the physical system. 相似文献
983.
李四超 《海军航空工程学院学报》2016,31(4):475-479, 484
在对流固耦合仿真计算方法分析的基础上,建立起水下航行体舵板张开过程的仿真计算模型,采用该模型 对舵板张开过程的角速度、载荷以及响应等变化规律进行了研究。在水下航行体发射试验中,对舵板张开角度、舵 板应变等参数进行了测试,对测试获取的数据与仿真结果进行了对比分析,研究表明二者一致性较好,能够为水下 航行体的水弹道分析和舵板的结构设计、材料选择等提供指导。 相似文献