全文获取类型
收费全文 | 5288篇 |
免费 | 11篇 |
国内免费 | 14篇 |
专业分类
航空 | 2343篇 |
航天技术 | 1756篇 |
综合类 | 22篇 |
航天 | 1192篇 |
出版年
2021年 | 42篇 |
2019年 | 33篇 |
2018年 | 209篇 |
2017年 | 160篇 |
2016年 | 103篇 |
2015年 | 47篇 |
2014年 | 120篇 |
2013年 | 135篇 |
2012年 | 147篇 |
2011年 | 269篇 |
2010年 | 217篇 |
2009年 | 301篇 |
2008年 | 353篇 |
2007年 | 234篇 |
2006年 | 117篇 |
2005年 | 156篇 |
2004年 | 139篇 |
2003年 | 161篇 |
2002年 | 109篇 |
2001年 | 165篇 |
2000年 | 84篇 |
1999年 | 94篇 |
1998年 | 110篇 |
1997年 | 82篇 |
1996年 | 103篇 |
1995年 | 120篇 |
1994年 | 118篇 |
1993年 | 70篇 |
1992年 | 100篇 |
1991年 | 44篇 |
1990年 | 41篇 |
1989年 | 99篇 |
1988年 | 36篇 |
1987年 | 44篇 |
1986年 | 45篇 |
1985年 | 151篇 |
1984年 | 95篇 |
1983年 | 83篇 |
1982年 | 101篇 |
1981年 | 138篇 |
1980年 | 43篇 |
1979年 | 44篇 |
1978年 | 32篇 |
1977年 | 30篇 |
1976年 | 21篇 |
1975年 | 24篇 |
1974年 | 28篇 |
1973年 | 23篇 |
1972年 | 16篇 |
1970年 | 15篇 |
排序方式: 共有5313条查询结果,搜索用时 31 毫秒
951.
A. I. Tkachenko 《Cosmic Research》2011,49(2):150-159
A method to find and identify failures in a spacecraft’s set of sensitive elements that measure vector quantities of different
nature is discussed. 相似文献
952.
Takeru K. Suzuki 《Space Science Reviews》2011,158(2-4):339-363
We review our recent results of Alfvén wave-driven winds. First, we present the result of self-consistent 1D MHD simulations for solar winds from the photosphere to interplanetary region. Here, we emphasize the importance of the reflection of Alfvén waves in the density stratified corona and solar winds. We also introduce the recent Hinode observation that might detect the reflection signature of transverse (Alfvénic) waves by Fujimura and Tsuneta (Astrophys. J. 702:1443, 2009). Then, we show the results of Alfvén wave-driven winds from red giant stars. As a star evolves to the red giant branch, the properties of stellar winds drastically change from steady coronal winds to intermittent chromospheric winds. We also discuss how the stellar evolution affects the wave reflection in the stellar atmosphere and similarities and differences of accretion disk winds by MHD turbulence. 相似文献
953.
Hugh S. Hudson 《Space Science Reviews》2011,158(1):5-41
This article broadly reviews our knowledge of solar flares. There is a particular focus on their global properties, as opposed
to the microphysics such as that needed for magnetic reconnection or particle acceleration as such. Indeed solar flares will
always remain in the domain of remote sensing, so we cannot observe the microscales directly and must understand the basic
physics entirely via the global properties plus theoretical inference. The global observables include the general energetics—radiation
in flares and mass loss in coronal mass ejections (CMEs)—and the formation of different kinds of ejection and global wave
disturbance: the type II radio-burst exciter, the Moreton wave, the EIT “wave”, and the “sunquake” acoustic waves in the solar
interior. Flare radiation and CME kinetic energy can have comparable magnitudes, of order 1032 erg each for an X-class event, with the bulk of the radiant energy in the visible-UV continuum. We argue that the impulsive
phase of the flare dominates the energetics of all of these manifestations, and also point out that energy and momentum in
this phase largely reside in the electromagnetic field, not in the observable plasma. 相似文献
954.
E. M. Kraeva 《Russian Aeronautics (Iz VUZ)》2011,54(2):154-158
Based on the jet-vortex model for flow passage hydrodynamics in a high-speed centrifugal pump with the open-type impeller,
we present the calculated relations for design and optimization of the experimentally verified pump design parameters. 相似文献
955.
In this paper, one of the most possible methods for calculations of ejector devices equipped with the cylindrical mixing chambers
is considered; the method is based on averaging the flow parameters at the chamber inlet. We present the calculation results
and their comparison with the earlier published data, as well as the quantitative assessment of this method and feasibilities
of its use for different technical devices embodying the concept of ejection. 相似文献
956.
Some methods of optimizing a cutting tool kit by the minimum labour content criterion in milling of an article are considered.
Their advantages and disadvantages are given. 相似文献
957.
The scheme variants of implementing the thermal protection against heat flows being generated by the body of a high-temperature
stationary gas turbine engine (GTE) are presented. The scheme of the experimental bench with a working section is given. Methodical
approaches to the heat transfer calculation at different variants of forced and natural convection organization and under
various operating conditions are described. The generalized results of the experiments carried out using a heat curtain being
generated by porous injection are presented. 相似文献
958.
B. I. Mamaev 《Russian Aeronautics (Iz VUZ)》2011,54(2):159-164
Some design and experimental data on three cascades with the same 12° bending angle for the primary nozzle block of a gas
turbine are presented. As is seen from the investigation the most efficient at the transonic velocities of the outward flow
are the blades, the back curvature of which in the bevel cut zone decreases to the trailing edge. Also presented is the fact
that the blade with the increasing back curvature has noticeably larger losses. 相似文献
959.
The results of investigation of dynamic system sensitivity to parametric variations in the channel of flight vehicle lateral
motion are presented using the notion of infinitesimal transformation. The exact relationships establishing a link between
the structure of parameter deviation and that of system phase coordinate deviation are obtained. 相似文献
960.
Anoop Kumar Mishra R.M. Gairola A.K. Varma Vijay K. Agarwal 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The GOES Precipitation Index (GPI) technique (Arkin, 1979) for rainfall estimation has been in operation for the last three decades. However, its applications are limited to the larger temporal and spatial scales. The present study focuses on the augmentation on GPI technique by incorporating a moisture factor for the environmental correction developed by Vicente et al. (1998). It consists of two steps; in the first step the GPI technique is applied to the Kalpana-IR data for rainfall estimation over the Indian land and oceanic region and in the second step an environmental moisture correction factor is applied to the GPI-based rainfall to estimate the final rainfall. Detailed validation with rain gauges and comparison with Tropical Rainfall Measuring Mission (TRMM) merged data product (3B42) are performed and it is found that the present technique is able to estimate the rainfall with better accuracy than the GPI technique over higher temporal and spatial domains for many operational applications in and around the Indian regions using Indian geostationary satellite data. Further comparison with the Doppler Weather Radar shows that the present technique is able to retrieve the rainfall with reasonably good accuracy. 相似文献