全文获取类型
收费全文 | 5700篇 |
免费 | 13篇 |
国内免费 | 29篇 |
专业分类
航空 | 2574篇 |
航天技术 | 2175篇 |
综合类 | 19篇 |
航天 | 974篇 |
出版年
2021年 | 54篇 |
2019年 | 40篇 |
2018年 | 120篇 |
2017年 | 82篇 |
2016年 | 72篇 |
2015年 | 25篇 |
2014年 | 126篇 |
2013年 | 164篇 |
2012年 | 155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 | 41篇 |
1987年 | 41篇 |
1986年 | 58篇 |
1985年 | 172篇 |
1984年 | 132篇 |
1983年 | 106篇 |
1982年 | 132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5742条查询结果,搜索用时 15 毫秒
511.
D F Smart M A Shea 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,31(1):45-50
Estimates of the energetic proton environment for a Mars mission are generally extrapolated from the solar proton observations at 1 AU. We find that solar particle events may be divided into two general classes. Events dominated by a near-sun injection of particles onto interplanetary magnetic field lines leading to the spacecraft position represent the "classical" solar particle event associated with solar activity. This class of event will scale in radial distance by the classical power law extrapolation. The extended-interplanetary-shock source generates a maximum flux as the shock passes the detection location. This class of event typically generates maximum fluence, but in this case, the flux and fluence will not scale in the classical manner with radial distance. 相似文献
512.
A new procedure for restoration of the plasma inhomogeneities with improved resolution is suggested. The procedure deals with the double weighted Fourier transform (DWFT) of the observed wavefield in coordinates of both receivers = (x, y) and sources
0 = (x
0, y
0) [1]. Phase increments between the sources and receivers, being found from DWFT representation, can be used for extracting information on small perturbations of the dielectric constant ~(, z) in a way similar to traditional radio tomography. The resulting resolution of the method is close to the diffraction limit = h/D in the horizontal direction and z = (h/D)2 in the vertical direction, where h is the height of inhomogeneities and D is the length of the ground-based receiving system. 相似文献
513.
This article presents main scientific and practical results obtained in course of scientific and applied research and experiments on Mir space station. Based on Mir experience, processes of research program formation for the Russian Segment of the ISS are briefly described. The major trends of activities planned in the frames of these programs as well as preliminary results of increment research programs implementation in the ISS' first missions are also presented. 相似文献
514.
Expedition teams provide a number of analogs relevant to crew selection for long-duration space missions. Three groups were studied that varied in team composition. Group 1 was a two woman international dyad that traversed the Antarctic continent in 97 days. Similarities in problem solving approach, respect for each other's opinions, and a collaborative process of decision making were evident. Group 2 was composed of four women, all from different countries, engaged in a six week trek across Greenland. The most important factors in overcoming interpersonal difficulties and contributing to the successful completion of the expedition were mutual respect and motivation to maintain positive and supportive relationships. Group 3 consisted of three married couples from different countries icelocked on a boat in the High Arctic for a 9 month period. The emotional support of and ability to confide in their partner were extremely important in alleviating interpersonal tensions, and contributed to the generally effective functioning of the group. Women add an element of emotional support and help to other team members that is not as evident in all-male groups. Selection of couples with strong bonds to each other is another paradigm for crew selection for extended missions. 相似文献
515.
A V Shafirkin V M Petrov A V Kolomensky V A Shurshakov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(4):999-1003
This paper presents results of calculations of total radiation risk for cosmonauts over their lifetimes and assessments of possible shortening of life expectancy on the basis of generalized doses calculated for cosmonauts after a long term interplanetary and orbital space missions on "MIR" station and International Space Station with the use of mathematical expressions coming from a model of change mortality rate of mammals after irradiation. Tumor risk assessments for cosmonauts over lifetime after flights are also given. Dependences of the delayed radiation consequences mentioned above on flight duration, spacecraft shielding thicknesses, solar activity and cosmonauts' age are analyzed. 相似文献
516.
517.
Avdeev S Bidoli V Casolino M De Grandis E Furano G Morselli A Narici L De Pascale MP Picozza P Reali E Sparvoli R Boezio M Carlson P Bonvicini W Vacchi A Zampa N Castellini G Fuglesang C Galper A Khodarovich A Ozerov Y Popov A Vavilov N Mazzenga G Ricci M Sannita WG Spillantini P 《Acta Astronautica》2002,50(8):511-525
The phenomenon of light flashes (LF) in eyes for people in space has been investigated onboard Mir. Data on particles hitting the eye have been collected with the SilEye detectors, and correlated with human observations. It is found that a nucleus in the radiation environment of Mir has roughly a 1% probability to cause an LF, whereas the proton probability is almost three orders of magnitude less. As a function of LET, the LF probability increases above 10 keV/micrometer, reaching about 5% at around 50 keV/micrometer. 相似文献
518.
The started assembly of the International Space Station (ISS) and its further operation will call for a great number of extravehicular activity sorties (EVA) to be performed by ISS crews. Therefore, of great importance is to make use of the EVA experience gained by cosmonauts in the process of 15-year operation of the Mir orbiting station (OS). Over the 15-year period, Mir crewmembers wearing Orlan type semi-rigid space suits have accumulated 158 man/sorties from the orbiting station. Crewmembers used 15 suits in orbit and some of the suits were in operation for more than 3 years. The paper presents principal design features, which provide effective and safe operation of orbit-based suits, and briefly describes procedures for preparation and maintenance of suit systems, which ensure long-term operation of space suit in orbit. The paper gives results of the space suit modifications, presents suit performance characteristics and lists novel or upgraded components of the space suit and its systems. The paper also summarizes improvements in the Orlan type suits described in some earlier publications. They refer, in the first run, to the improvement of space suit operations characteristics and reliability, and the utilization of the Orlan type space suit in the ISS program. The paper analyses the experience gained and drawbacks detected and observations made, and gives statistical data on long-term space suit operations aboard the Mir station. The paper reviews certain problems in the process of EVAs performed from the station, and describes the ways of their solution as applied to the further utilization of the suit within the ISS program. 相似文献
519.
V Bidoli M Casolino M P De Pascale G Furano A Morselli L Narici P Picozza E Reali R Sparvoli A M Galper A V Ozerov YuVPopov N R Vavilov A P Alexandrov S V Avdeev Y u Baturin Y u Budarin G Padalko V G Shabelnikov G Barbellini W Bonvicini A Vacchi N Zampa S Bartalucci G Mazzenga M Ricci O Adriani P Spillantini M Boezio P Carlson C Fuglesang G Castellini W G Sannita 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2000,25(10):2075-2079
The SilEye experiment aims to study the cause and processes related to the anomalous Light Flashes (LF) perceived by astronauts in orbit and their relation with Cosmic Rays. These observations will be also useful in the study of the long duration manned space flight environment. Two PC-driven silicon detector telescopes have been built and placed aboard Space Station MIR. SilEye-1 was launched in 1995 and provided particles track and LF information; the data gathered indicate a linear dependence of FLF(Hz) ( 4 2) 10(3) 5.3 1.7 10(4) Fpart(Hz) if South Atlantic Anomaly fluxes are not included. Even though higher statistic is required, this is an indication that heavy ion interactions with the eye are the main LF cause. To improve quality and quantity of measurements, a second apparatus, SilEye-2, was placed on MIR in 1997, and started work from August 1998. This instrument provides energetic information, which allows nuclear identification in selected energy ranges; we present preliminary measurements of the radiation field inside MIR performed with SilEye-2 detector in June 1998. 相似文献
520.
The sopite syndrome is a poorly understood response to motion. Drowsiness and mood changes are the primary characteristics of the syndrome. The sopite syndrome can exist in isolation from more apparent symptoms such as nausea, can last long after nausea has subsided, and can debilitate some individuals. It is most likely a distinct syndrome from "regular" motion sickness or common fatigue, and is of potential concern in a variety of situations. The syndrome may be particularly hazardous in transportation settings where other performance challenges (e.g., sleep deprivation) are already present. It is also a potential concern in cases where illnesses such as sleep disorders or depression may interact with the syndrome and confuse diagnosis. 相似文献