全文获取类型
收费全文 | 109篇 |
免费 | 21篇 |
国内免费 | 25篇 |
专业分类
航空 | 61篇 |
航天技术 | 29篇 |
综合类 | 5篇 |
航天 | 60篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 18篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 1篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 15 毫秒
141.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(1):408-419
Asymmetrical spin stabilized satellite dynamics in the vicinity of the required motion is considered. The principal axis of the maximum moment of inertia slightly deviates from its assumed direction in the satellite reference frame. This is formalized in the cross products of inertia. This inertial uncertainty results in a wobble, that is undesired angular velocity components perpendicular to the rotation axis, and oscillations of this axis near the required direction. The torque-free motion is investigated first. Expressions that explicitly relate satellite inertia parameters to wobble are provided. Wobble evolution under the action of magnetic damping control is analyzed next. Its amplitude approximate exponential decay behavior and residual unavoidable wobble level are derived. These expressions are compared with numerical simulation results of nonlinear equations of motion including various disturbance sources. 相似文献
142.
Palash K. Sarker Jun-ichi Takahashi Yumiko Obayashi Takeo Kaneko Kensei Kobayashi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Aqueous solutions of 5-substituted hydantoins were irradiated with ultraviolet (UV) light, to investigate their structural stability against UV radiation as well as the possible photolysis products. The photolysis products were identified and the degree of photolysis was measured using reversed-phase and ion-exchange high-performance liquid chromatography. Hydantoin (2,4-imidazolidinedione) was dominantly detected as a photolysis product of 5-substituted hydantoins. With hydrolysis of UV-irradiated 5-substituted hydantoins, glycine and alanine were dominantly detected. These experimental results are important for the prebiotic photochemistry of 5-substituted hydantoins in the formation of hydantoin since they have been detected in Solar System materials. 相似文献
143.
分析了油品在管道中静电起电的因素,在此基础上,采用Fuzzy评价方法,建立了油品静电评价模型。最后提出了消除油品静电的方法。 相似文献
144.
航空产品加速寿命试验研究及应用 总被引:11,自引:0,他引:11
张苹苹 《北京航空航天大学学报》1995,21(4):124-129
对加速寿命试验的理论及航空产品加速寿命试验的实例进行了简要阐述,并对航空机械产品的可靠性加速寿命试验与长试等效加速寿命试验的特点及困难进行了初步的分析,对今后的研究提出了一些看法。应用实例中的方法和结论对同类航空产品有积极的参考价值。 相似文献
145.
国际贸易中绿色贸易壁垒问题不可回避,农业作为一种弱质产业更容易受其影响。就我国农产品如何突破绿色壁垒、扩大农产品出口提出一些政策选择。 相似文献
146.
在中文文献中,同一苏/俄航天服俄文名称有多个中文译名,极易引起混淆与误解。为此,短文提出统一(或约定)苏/俄航天服中文译名的建议,可供使用者参考。 相似文献
147.
In 2009 President Obama proposed a budget for the National Aeronautics and Space Administration (NASA) that canceled the Constellation program and included the development of commercial crew transportation systems into low Earth orbit. This significant move to shift human spaceflight into the private sector sparked political debate, but much of the discourse has focused on impacts to “safety.” Although no one disputes the importance of keeping astronauts safe, strategies for defining safety reveal contrasting visions for the space program and opposing values regarding the privatization of U.S. space exploration. In other words, the debate over commercial control has largely become encoded in arguments over safety. Specifically, proponents of using commercial options for transporting astronauts to the International Space Station (ISS) argue that commercial vehicles would be safe for astronauts, while proponents of NASA control argue that commercial vehicles would be unsafe, or at least not as safe as NASA vehicles. The cost of the spaceflight program, the technical requirements for designing a vehicle, the track record of the launch vehicle, and the experience of the launch provider are all incorporated into what defines safety in human spaceflight. This paper analyzes these contested criteria through conceptual lenses provided by fields of science and technology policy (STP) and science, technology, and society (STS). We ultimately contend that these differences in definition result not merely from ambiguous understandings of safety, but from intentional and strategic choices guided by normative positions on the commercialization of human spaceflight. The debate over safety is better considered a proxy debate for the partisan preferences embedded within the dispute over public or private spaceflight. 相似文献
148.
149.
载人飞船的开伞控制方案是回收着陆系统设计中的一个关键环节,它直接关系到飞船回收着陆系统工作的成败。文章根据载人飞船特点的分析,制订了飞船开伞控制方案,即采用静压高度控制法来控制开伞,然后根据静压高度控制的工作原理,详细介绍了开伞控制方案的设计方法和流程。仿真试验和飞行试验结果表明:"神舟号"载人飞船开伞控制方案的设计是合理的、正确的。 相似文献
150.