全文获取类型
收费全文 | 137篇 |
免费 | 32篇 |
国内免费 | 23篇 |
专业分类
航空 | 139篇 |
航天技术 | 35篇 |
综合类 | 10篇 |
航天 | 8篇 |
出版年
2023年 | 8篇 |
2022年 | 11篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 11篇 |
2013年 | 10篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 4篇 |
2006年 | 11篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 16篇 |
1998年 | 4篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1984年 | 3篇 |
排序方式: 共有192条查询结果,搜索用时 83 毫秒
71.
72.
The film cooling effectiveness of two turbine blades at different turbulence intensities(0.62% and 16.00%) and mass flux ratios(2.91%, 5.82%, 8.73% and 11.63%) is studied by using the Pressure-Sensitive Paint(PSP) measurement technique. There are a baseline and an improved turbine blade in current work, and their film cooling hole position distribution is the same. But the hole shape on suction surface and pressure surface is changed from cylindrical hole(baseline)to laid-back fan-shaped hole(im... 相似文献
73.
黄维扬 《南京航空航天大学学报》1986,(2)
本文应用广义变分原理,给出了含圆孔的有限大平板应力集中的计算公式。並对矩形板单向均匀拉伸和剪切两种情况进行了数值计算,将计算结果绘成了曲线。 相似文献
74.
提出了一种结合图像中值滤波和试件参考点的风洞压敏涂料(PSP)试验图像数据处理方法。与通常用校准箱获取校准曲线进而得到PSP试验试件表面压力或压力系数(Cp)的方法不同,该方法通过空心中值滤波技术恢复PSP光强比图像中测压孔处的光强比数据,结合若干参考点处常规测压技术实测所得Cp值,获得Cp值和PSP图像光强比数据的关系曲线,进而得到整个试件表面的Cp值数据,该方法获得的数据结合了风洞试验诸多因素对试验结果的影响。利用MATLAB对PSP技术试验图像数据进行了处理,并将PSP方法获得的Cp值与常规测压方法获得的Cp值进行了比较,得到的结果显示,笔者采用的方法获得的Cp值与常规测压方法获得的Cp值吻合较好。该方法为PSP图像数据的处理提供了一种新的方法,具有较大的发展潜力和应用价值。 相似文献
75.
Dipak Debnath Sandip K. Chakrabarti Anuj Nandi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The Galactic black hole candidate H 1743-322 exhibited two X-ray outbursts in rapid succession: one in August 2010 and the other in April 2011. We analyze archival data of this object from the PCA instrument on board RXTE (2–25 keV energy band) to study the evolution of its temporal and spectral characteristics during both the outbursts, and hence to understand the behavioral change of the accretion flow dynamics associated with the evolution of the various X-ray features. We study the evolution of QPO frequencies during the rising and the declining phases of both the outbursts. We successfully fit the variation of QPO frequency using the Propagating Oscillatory Shock (POS) model in each of the outbursts and obtain the accretion flow parameters such as the instantaneous shock locations, the shock velocity and the shock strength. Based on the degree of importance of the thermal (disk black body) and the non-thermal (power-law) components of the spectral fit and properties of the QPO (if present), the entire profiles of the 2010 and 2011 outbursts are subdivided into four different spectral states: hard, hard-intermediate, soft-intermediate and soft. We attempt to explain the nature of the outburst profile (i.e., hardness-intensity diagram) with two different types of mass accretion flow. 相似文献
76.
77.
Wei-Tou Ni 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The detection of low frequency band (100 nHz–100 mHz) and very low frequency band (300 pHz–100 nHz) gravitational waves (GWs) is important for exploration of the equation of state of dark energy and the co-evolution of massive black holes (MBHs) with galaxies. Most galaxies are believed to have a massive black hole in the galactic core. In the formation of these black holes, merging and accretion are the two main processes. Merging of massive black holes generate GWs which could be detected by space GW detectors and Pulsar Timing Arrays (PTAs) to cosmological distances. LISA (Laser-Interferometric Space Antenna) is most sensitive to the frequency band 1 mHz–100 mHz, ASTROD-GW (ASTROD [Astrodynamical Space Test of Relativity using Optical Devices] optimized for Gravitational Wave detection) is most sensitive to the frequency band 100 nHz–1 mHz and PTAs are most sensitive to the frequency band 300 pHz–100 nHz. In this paper, we discuss the sensitivities and outlooks of detection of GWs from binary massive black holes in these frequency bands with an emphasis on ASTROD-GW. The GWs generated by the inspirals, merging and subsequent ringdowns of binary black holes are standard sirens to the cosmological distance. Using GW observations, we discuss the methods for determining the equation of state of dark energy and for testing the co-evolution models of massive black holes. ASTROD-GW is an optimization of ASTROD to focus on the goal of detection of GWs. The mission orbits of the 3 spacecraft forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4 and L5. The 3 spacecraft range interferometrically with one another with arm length about 260 million kilometers. With 52 times longer in arm length compared to that of LISA, the strain detection sensitivity is 52 times better toward larger wavelength. The scientific aim is focused for gravitational wave detection at low frequency. The science goals include detection of GWs from MBHs, and Extreme-Mass-Ratio Black Hole Inspirals (EMRI), and using these observations to find the evolution of the equation of state of dark energy and to explore the co-evolution of massive black holes with galaxies. 相似文献
78.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(7):1843-1851
Accurate measurements of the solar differential rotation parameters are necessary for understanding the solar dynamo mechanism. We use the orthogonalization process to estimate these parameters. The advantage of the orthogonalization of the data in the tracer motion statistical analysis is outlined. The differential rotation is represented in terms of various types of polynomials. We compare the quality of a set of models of the solar differential rotation using the Akaike information criterion and choose the best one. Applying the proposed method, we studied the solar differential rotation and its North-South asymmetry using observations of coronal holes. A statistical analysis of observations from the Atmospheric Imaging Assembly (AIA) on Solar Dynamics Observatory (SDO) reveals the differential rotation pattern of coronal holes and its North-South asymmetry. 相似文献
79.
P. Jovanović V. Borka Jovanović D. Borka T. Bogdanović 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
We used a model of a relativistic accretion disk around a supermassive black hole (SMBH), based on ray-tracing method in the Kerr metric, to study the variations of the composite Fe Kα line emitted from two accretion disks around SMBHs in a binary system. We assumed that the orbit of such a binary is approximately Keplerian, and simulated the composite line shapes for different orbital elements, accretion disk parameters and mass ratios of the components. The obtained results show that, if observed in the spectra of some SMBH binaries during their different orbital phases, such composite Fe Kα line profiles could be used to constrain the orbits and several properties of such SMBH binaries. 相似文献
80.
Larmor size transient structures with density depletions as large as 99% of ambient solar wind density levels occur commonly upstream of Earth's collisionless bow shock. These "density holes" have a me... 相似文献