全文获取类型
收费全文 | 5696篇 |
免费 | 9篇 |
国内免费 | 29篇 |
专业分类
航空 | 2574篇 |
航天技术 | 2166篇 |
综合类 | 19篇 |
航天 | 975篇 |
出版年
2021年 | 54篇 |
2019年 | 40篇 |
2018年 | 119篇 |
2017年 | 81篇 |
2016年 | 71篇 |
2015年 | 25篇 |
2014年 | 126篇 |
2013年 | 163篇 |
2012年 | 156篇 |
2011年 | 228篇 |
2010年 | 147篇 |
2009年 | 257篇 |
2008年 | 314篇 |
2007年 | 168篇 |
2006年 | 145篇 |
2005年 | 174篇 |
2004年 | 177篇 |
2003年 | 198篇 |
2002年 | 123篇 |
2001年 | 183篇 |
2000年 | 128篇 |
1999年 | 139篇 |
1998年 | 158篇 |
1997年 | 125篇 |
1996年 | 153篇 |
1995年 | 197篇 |
1994年 | 178篇 |
1993年 | 93篇 |
1992年 | 144篇 |
1991年 | 49篇 |
1990年 | 51篇 |
1989年 | 127篇 |
1988年 | 40篇 |
1987年 | 40篇 |
1986年 | 58篇 |
1985年 | 172篇 |
1984年 | 131篇 |
1983年 | 105篇 |
1982年 | 131篇 |
1981年 | 154篇 |
1980年 | 45篇 |
1979年 | 30篇 |
1978年 | 37篇 |
1977年 | 36篇 |
1976年 | 29篇 |
1975年 | 26篇 |
1974年 | 34篇 |
1973年 | 25篇 |
1970年 | 27篇 |
1969年 | 24篇 |
排序方式: 共有5734条查询结果,搜索用时 15 毫秒
451.
D.?V.?ChuguninEmail author G.?A.?Kotova M.?V.?Klimenko V.?V.?Klimenko 《Cosmic Research》2017,55(6):457-463
The paper has presented a study of the dependence of the H+ ions concentration in the plasmasphere on geographic longitude. A vast database of measurements of the cold plasma density by the Alpha-3 instrument on board the INTERBALL-1 satellite has been used for the study. Based on these measurements, a dependence of the H+ ions concentration in the filled magnetic flux tube in the plasmasphere in the equatorial plane under quiet geomagnetic conditions has been obtained as a function of geographic longitude. Studies have been performed for two seasons, summer and winter. It has been shown that, during the summer in the near-midnight sector, the minimum in the H+ concentration falls within geographic longitudes of 270°–315°. The ratio of the concentration of H+ ions at various longitudes could reach a factor of three. During the winter, in the near-noon sector, the maximum of the H+ ions concentration falls within longitudes of 180°–225°, whereas the concentration ratio could reach a factor of 2.2. 相似文献
452.
Y. I. Yermolaev I. G. Lodkina N. S. Nikolaeva M. Y. Yermolaev M. O. Riazantseva 《Cosmic Research》2017,55(3):178-189
This paper discusses the errors in analyzing solar-terrestrial relationships, which result from either disregarding the types of interplanetary drivers in studying the magnetosphere response on their effect or from the incorrect identification of the type of these drivers. In particular, it has been shown that the absence of selection between the Sheath and ICME (the study of so-called CME-induced storms, i.e., magnetic storms generated by CME) leads to errors in the studies of interplanetary conditions of magnetic storm generation, because the statistical analysis has shown that, in the Sheath + ICME sequences, the largest number of storm onsets fell on the Sheath, and the largest number of storms maxima fell at the end of the Sheath and the beginning of the ICME. That is, the situation is observed most frequently when at least the larger part of the main phase of storm generation falls on the Sheath and, in reality, Sheath-induced storms are observed. In addition, we consider several cases in which magnetic storms were generated by corotating interaction regions, whereas the authors attribute them to CME. 相似文献
453.
I.?N.?MyagkovaEmail author S.?I.?Svertilov A.?S.?Kovtyukh V.?V.?Bogomolov A.?V.?Bogomolov M.?I.?Panasyuk D.?V.?Sibiryakova E.?V.?Balan 《Cosmic Research》2017,55(1):72-78
The variations in the spatial structure and time in electron fluxes with E = 235–300 keV in the slot region (2 < L < 3) between the radiation belts in the period of November 1, 2014 through December 8, 2014 during weak and moderate geomagnetic disturbances (Kp < 4, Dst >–60 nT) are analyzed based on the data of the RELEC complex on board the Vernov satellite (the height and inclination of the orbit are from 640 to 830 km and 98.4°, respectively). Irregular increases in the fluxes of such electrons and formation of a local maximum at L ~ 2.2–3.0 were observed. It has been shown that the intensity of this maximum is inversely proportional to the L value and grows with an increase in the geomagnetic activity level. New features discovered for the first time in the dynamics of radiation belt electrons manifest in the variations in the local structure and dynamics of fluxes of subrelativistic electrons in the slot region. 相似文献
454.
In the 1990s, based on detailed studies of the structure of active regions (AR), the concept of the magnetosphere of the active region was proposed. This includes almost all known structures presented in the active region, ranging from the radio granulation up to noise storms, the radiation of which manifests on the radio waves. The magnetosphere concept, which, from a common point of view, considers the manifestations of the radio emission of the active region as a single active complex, allows one to shed light on the relation between stable and active processes and their interrelations. It is especially important to identify the basic ways of transforming nonthermal energy into thermal energy. A dominant role in all processes is attributed to the magnetic field, the measurement of which on the coronal levels can be performed by radio-astronomical techniques. The extension of the wavelength range and the introduction of new tools and advanced modeling capabilities makes it possible to analyze the physical properties of plasma structures in the AR magnetosphere and to evaluate the coronal magnetic fields at the levels of the chromosphere–corona transition zone and the lower corona. The features and characteristics of the transition region from the S component to the B component have been estimated. 相似文献
455.
A wireless sensor system for data acquisition and processing during structural and fatigue tests is considered. A prototype of wireless strain-gauge measurement system is used in fatigue tests of a utility helicopter’s main rotor hub. The setup of the test rig and software are described. 相似文献
456.
In the paper, processes of high-energy electron beam interaction with plasma particles in a discharge channel of a stationary plasma thruster are analyzed and the results are presented. 相似文献
457.
S. O. Karpenko N. V. Kupriyanova M. Yu. Ovchinnikov V. I. Penkov A. S. Selivanov O. E. Khromov 《Cosmic Research》2010,48(6):517-525
The results of designing the attitude control system of the first Russian nanosatellite TNS-0 no. 1 providing orientation of its longitudinal axis along the local geomagnetic field induction vector are presented. The system
consists of a permanent magnet and two sets of hysteresis rods. The magnetic and geometric parameters of the magnet and rods
are calculated. The influence of the permanent magnet field on the hysteresis rods and mutual influence of the rods in the
case of compact satellite packaging are analyzed. Examples of calculations of transient processes and steady-state angular
satellite motion are presented. 相似文献
458.
459.
V. M. Soldatkin A. A. Arkhipov V. A. Olaev A. A. Uglov 《Russian Aeronautics (Iz VUZ)》2012,55(2):184-191
We consider the function, the problems being solved and the construction principles for a starting system of warning the critical regimes for a single-rotor helicopter at parking, taxiing and maneuvering on the ground, takeoff and landing as well as at descending and hovering regimes. The structural-functional scheme and the algorithms of system channel warning are presented. 相似文献
460.
The Juno Waves Investigation 总被引:1,自引:0,他引:1
W. S. Kurth G. B. Hospodarsky D. L. Kirchner B. T. Mokrzycki T. F. Averkamp W. T. Robison C. W. Piker M. Sampl P. Zarka 《Space Science Reviews》2017,213(1-4):347-392
Jupiter is the source of the strongest planetary radio emissions in the solar system. Variations in these emissions are symptomatic of the dynamics of Jupiter’s magnetosphere and some have been directly associated with Jupiter’s auroras. The strongest radio emissions are associated with Io’s interaction with Jupiter’s magnetic field. In addition, plasma waves are thought to play important roles in the acceleration of energetic particles in the magnetosphere, some of which impact Jupiter’s upper atmosphere generating the auroras. Since the exploration of Jupiter’s polar magnetosphere is a major objective of the Juno mission, it is appropriate that a radio and plasma wave investigation is included in Juno’s payload. This paper describes the Waves instrument and the science it is to pursue as part of the Juno mission. 相似文献