全文获取类型
收费全文 | 3321篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
航空 | 1311篇 |
航天技术 | 1041篇 |
综合类 | 19篇 |
航天 | 967篇 |
出版年
2022年 | 15篇 |
2021年 | 37篇 |
2019年 | 16篇 |
2018年 | 183篇 |
2017年 | 134篇 |
2016年 | 116篇 |
2015年 | 44篇 |
2014年 | 111篇 |
2013年 | 137篇 |
2012年 | 118篇 |
2011年 | 167篇 |
2010年 | 131篇 |
2009年 | 193篇 |
2008年 | 192篇 |
2007年 | 126篇 |
2006年 | 74篇 |
2005年 | 102篇 |
2004年 | 96篇 |
2003年 | 106篇 |
2002年 | 83篇 |
2001年 | 117篇 |
2000年 | 36篇 |
1999年 | 53篇 |
1998年 | 61篇 |
1997年 | 42篇 |
1996年 | 43篇 |
1995年 | 80篇 |
1994年 | 61篇 |
1993年 | 37篇 |
1992年 | 47篇 |
1991年 | 10篇 |
1990年 | 19篇 |
1989年 | 41篇 |
1988年 | 11篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 70篇 |
1984年 | 56篇 |
1983年 | 48篇 |
1982年 | 42篇 |
1981年 | 82篇 |
1980年 | 25篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 13篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1972年 | 13篇 |
1971年 | 11篇 |
排序方式: 共有3338条查询结果,搜索用时 15 毫秒
921.
A procedure of calculating an axial radial-flow centrifugal stage is considered. Using the gas-dynamically expedient load ratio distribution in profile, the process of impeller flow passage profiling is described. Also given are some techniques for decreasing or eliminating a wake zone as well as a graph of loss dependence on the divergence factor and velocity deceleration on the rarefaction side of the blade channel at the impeller outlet. 相似文献
922.
D. Yu. Kolodyazhnyi V. S. Nagornyi A. M. Sipatov V. Ya. Modorskii 《Russian Aeronautics (Iz VUZ)》2017,60(1):97-102
A technique for calculating the two-phase flows in the pneumatic injector of the aircraft engine is developed based on solving the model problem, namely, on verification of the two-phase flow model by means of solving the problem of liquid column disintegration under the effect of an incident airflow. We determine the turbulence models that satisfactorily describe the biphase flow processes. 相似文献
923.
V. P. Shabansky 《Space Science Reviews》1968,8(3):366-454
In this paper we consider those processes mainly related to the behaviour of the low-energetic magnetospheric plasma, which nevertheless contains the main mass and the predominant part of the thermal energy. Our attention has been concentrated on those processes which, from our point of view, determine geomagnetic phenomena on the surface of the earth. Because of the scope of the project, we had to exclude the processes of acceleration of high-energetic particles in the tail of the magnetosphere, their diffusion deep within, and the formation of the radiation belts. These problems are of independent interest and may be considered separately.When describing various phenomena we tried to stress the principal side of a question without regard to the details of one theory or other, though we did not keep to this principle throughout. Together with the results which are dealt with in the literature, we took the risk of including those considerations which are not as yet published. It mainly concerns Sections 2.3, 2.4, 3.4, 3.6, 3.7, and 4. where, together with other problems, three new hypotheses of the main phase of a storm and of Sq-variations are discussed. We prefer the mechanism connected with the current induction in the ionosphere (Section 4.4). For this purpose some aspects of magnetohydrodynamics were examined (Section 4.3). 相似文献
924.
Features of fuel atomization and propagation in the flow behind a gas-dynamic stabilizer are considered. Estimations of the influence of transverse jets impulse magnitude on characteristics of mixing behind the stabilizer are obtained by numerical and experimental methods. 相似文献
925.
In this paper, a model of heat exchange and resistance in the channels with cylindrical grooves on the walls is presented. We compare the calculated data with the experimental results and give some recommendations for designers of power plants. 相似文献
926.
The solution is constructed based on using the general theory of physically orthotropic shells generalizing the Vlasov equations. The numerical results demonstrating the orthotropy influence on the stress strain state are presented. 相似文献
927.
B. V. Nerubailo 《Russian Aeronautics (Iz VUZ)》2014,57(2):127-133
The solution is obtained based on the differential equations for the general theory of shells and approximate equations that are the components of the method of asymptotic synthesis. Numerical results are presented. 相似文献
928.
We consider a probabilistic estimation of microaccelerations being produced in the inboard environment of an orbital laboratory as a random process; based on this estimation we analyzed a probability of fulfilling the favorable conditions to realize gravity-sensitive processes. The approach suggested can be applied when designing a space laboratory to meet the requirements for the microaccelerations inside the working zone of technological equipment. 相似文献
929.
930.
M.A. Chernigovskaya B.G. Shpynev A.S. Yasyukevich D.S. Khabituev K.G. Ratovsky A.Yu. Belinskaya A.E. Stepanov V.V. Bychkov S.A. Grigorieva V.A. Panchenko D. Kouba J. Mielich 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(2):762-776
We present a joint analysis of longitude-temporal variations of ionospheric and geomagnetic parameters at middle and high latitudes in the Northern Hemisphere during the two severe magnetic storms in March and June 2015 by using data from the chains of magnetometers, ionosondes and GPS/GLONASS receivers. We identify the fixed longitudinal zones where the variability of the magnetic field is consistently high or low under quiet and disturbed geomagnetic conditions. The revealed longitudinal structure of the geomagnetic field variability in quiet geomagnetic conditions is caused by the discrepancy of the geographic and magnetic poles and by the spatial anomalies of different scales in the main magnetic field of the Earth. Variations of ionospheric parameters are shown to exhibit a pronounced longitudinal inhomogeneity with changing geomagnetic conditions. This inhomogeneity is associated with the longitudinal features of background and disturbed structure of the geomagnetic field. During the recovery phase of a storm, important role in dynamics of the mid-latitude ionosphere may belong to wave-like thermospheric disturbances of molecular gas, propagating westward for several days. Therefore, it is necessary to extend the time interval for studying the ionospheric effects of strong magnetic storms by a few days after the end of the magnetospheric source influence, while the disturbed regions in the thermosphere continues moving westward and causes the electron density decrease along the trajectories of propagation. 相似文献