全文获取类型
收费全文 | 2721篇 |
免费 | 2篇 |
国内免费 | 19篇 |
专业分类
航空 | 1351篇 |
航天技术 | 1073篇 |
综合类 | 10篇 |
航天 | 308篇 |
出版年
2019年 | 18篇 |
2018年 | 24篇 |
2017年 | 18篇 |
2016年 | 18篇 |
2014年 | 47篇 |
2013年 | 62篇 |
2012年 | 53篇 |
2011年 | 85篇 |
2010年 | 62篇 |
2009年 | 107篇 |
2008年 | 165篇 |
2007年 | 64篇 |
2006年 | 66篇 |
2005年 | 70篇 |
2004年 | 79篇 |
2003年 | 83篇 |
2002年 | 51篇 |
2001年 | 75篇 |
2000年 | 50篇 |
1999年 | 63篇 |
1998年 | 80篇 |
1997年 | 51篇 |
1996年 | 65篇 |
1995年 | 79篇 |
1994年 | 79篇 |
1993年 | 49篇 |
1992年 | 63篇 |
1991年 | 31篇 |
1990年 | 30篇 |
1989年 | 73篇 |
1988年 | 26篇 |
1987年 | 28篇 |
1986年 | 30篇 |
1985年 | 119篇 |
1984年 | 68篇 |
1983年 | 57篇 |
1982年 | 59篇 |
1981年 | 105篇 |
1980年 | 35篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 28篇 |
1976年 | 18篇 |
1975年 | 31篇 |
1974年 | 19篇 |
1973年 | 25篇 |
1972年 | 20篇 |
1971年 | 18篇 |
1970年 | 25篇 |
1969年 | 26篇 |
排序方式: 共有2742条查询结果,搜索用时 937 毫秒
811.
D. McComas F. Allegrini F. Bagenal P. Casey P. Delamere D. Demkee G. Dunn H. Elliott J. Hanley K. Johnson J. Langle G. Miller S. Pope M. Reno B. Rodriguez N. Schwadron P. Valek S. Weidner 《Space Science Reviews》2008,140(1-4):261-313
The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure the interaction between the solar wind and ions created by atmospheric loss from Pluto. These measurements provide a characterization of the total loss rate and allow us to examine the complex plasma interactions at Pluto for the first time. Constrained to fit within minimal resources, SWAP is optimized to make plasma-ion measurements at all rotation angles as the New Horizons spacecraft scans to image Pluto and Charon during the flyby. To meet these unique requirements, we combined a cylindrically symmetric retarding potential analyzer with small deflectors, a top-hat analyzer, and a redundant/coincidence detection scheme. This configuration allows for highly sensitive measurements and a controllable energy passband at all scan angles of the spacecraft. 相似文献
812.
The THEMIS Fluxgate Magnetometer 总被引:2,自引:0,他引:2
H. U. Auster K. H. Glassmeier W. Magnes O. Aydogar W. Baumjohann D. Constantinescu D. Fischer K. H. Fornacon E. Georgescu P. Harvey O. Hillenmaier R. Kroth M. Ludlam Y. Narita R. Nakamura K. Okrafka F. Plaschke I. Richter H. Schwarzl B. Stoll A. Valavanoglou M. Wiedemann 《Space Science Reviews》2008,141(1-4):235-264
813.
This chapter will review what is known about the charging of planetary rings, in particular the sum of the individual currents from the time-varying charge dQ/dt, of the planetary ring particle. For the smallest ring particles, in addition to checking the plasma conditions for the charging currents, one must consider if collective effects in the ring environment are relevant. Two planetary ring environments that have held a strong interest for ring scientists in the last two decades are Saturn’s spokes in the B Ring and the environment of Saturn’s E ring. Two sections of this chapter will describe these planetary ring charging environments in detail. Finally, we describe two charging effects that demonstrate areas of future studies while providing fresh examples of the intriguing effects from planetary ring charging processes. 相似文献
814.
R. P. Lepping M. H. Acũna L. F. Burlaga W. M. Farrell J. A. Slavin K. H. Schatten F. Mariani N. F. Ness F. M. Neubauer Y. C. Whang J. B. Byrnes R. S. Kennon P. V. Panetta J. Scheifele E. M. Worley 《Space Science Reviews》1995,71(1-4):207-229
The magnetic field experiment on WIND will provide data for studies of a broad range of scales of structures and fluctuation characteristics of the interplanetary magnetic field throughout the mission, and, where appropriate, relate them to the statics and dynamics of the magnetosphere. The basic instrument of the Magnetic Field Investigation (MFI) is a boom-mounted dual triaxial fluxgate magnetometer and associated electronics. The dual configuration provides redundancy and also permits accurate removal of the dipolar portion of the spacecraft magnetic field. The instrument provides (1) near real-time data at nominally one vector per 92 s as key parameter data for broad dissemination, (2) rapid data at 10.9 vectors s–1 for standard analysis, and (3) occasionally, snapshot (SS) memory data and Fast Fourier Transform data (FFT), both based on 44 vectors s–1. These measurements will be precise (0.025%), accurate, ultra-sensitive (0.008 nT/step quantization), and where the sensor noise level is <0.006 nT r.m.s. for 0–10 Hz. The digital processing unit utilizes a 12-bit microprocessor controlled analogue-to-digital converter. The instrument features a very wide dynamic range of measurement capability, from ±4 nT up to ±65 536 nT per axis in eight discrete ranges. (The upper range permits complete testing in the Earth's field.) In the FTT mode power spectral density elements are transmitted to the ground as fast as once every 23 s (high rate), and 2.7 min of SS memory time series data, triggered automatically by pre-set command, requires typically about 5.1 hours for transmission. Standard data products are expected to be the following vector field averages: 0.0227-s (detail data from SS), 0.092 s (detail in standard mode), 3 s, 1 min, and 1 hour, in both GSE and GSM coordinates, as well as the FFT spectral elements. As has been our team's tradition, high instrument reliability is obtained by the use of fully redundant systems and extremely conservative designs. We plan studies of the solar wind: (1) as a collisionless plasma laboratory, at all time scales, macro, meso and micro, but concentrating on the kinetic scale, the highest time resolution of the instrument (=0.022 s), (2) as a consequence of solar energy and mass output, (3) as an external source of plasma that can couple mass, momentum, and energy to the Earth's magnetosphere, and (4) as it is modified as a consequence of its imbedded field interacting with the moon. Since the GEOTAIL Inboard Magnetometer (GIM), which is similar to the MFI instrument, was developed by members of our team, we provide a brief discussion of GIM related science objectives, along with MFI related science goals. 相似文献
815.
816.
H. A. Thronson T. G. Hawarden A. J. Penny L. Vigroux G. Sholomitskii 《Space Science Reviews》1995,74(1-2):139-144
For five years, theEdison program has had the goal of developing new designs for infrared space observatories which will break the cost curve by permitting more capable missions at lower cost. Most notably, this has produced a series of models for purely radiative and radiative/mechanical (hybrid) cooling which do not use cryogens and optical designs which are not constrained by the coolant tanks. Purely radiatively-cooled models achieve equilibrium temperatures as low as about 20 K at a distance of 1 AU from the sun. More advancedEdison designs include mechanical cooling systems attached to the telescope assembly which lower the optical system temperature to 5 K or less. Via these designs, near-cryogenic temperatures appear achievable without the limitations of cryogenic cooling. OneEdison model has been proposed to the European Space Agency as the next generation infrared space observatory and is presently under consideration as a candidate ESA Cornerstone mission. The basic design is also the starting point for elements of future infrared space interferometers. 相似文献
817.
818.
L. Eliasson O. Norberg R. Lundin K. Lundin S. Olsen H. Borg M. André H. Koskinen P. Riihelä M. Boehm B. Whalen 《Space Science Reviews》1994,70(3-4):563-576
The Hot Plasma Experiment, F3H, on boardFreja is designed to measure auroral particle distribution functions with very high temporal and spatial resolution. The experiment consists of three different units; an electron spectrometer that measures angular and energy distributions simultaneously, a positive ion spectrometer that is using the spacecraft spin for three-dimensional measurements, and a data processing unit. The main scientific objective is to study positive ion heating perpendicular to the magnetic field lines in the auroral region. The high resolution measurements of different positive ion species and electrons have already provided important information on this process as well as on other processes at high latitudes. This includes for example high resolution observations of auroral particle precipitation features and source regions of positive ions during magnetic disturbances. TheFreja orbit with an inclination of 63° allows us to make detailed measurements in the nightside auroral oval during all disturbance levels. In the dayside, the cusp region is covered during magnetic disturbances. We will here present the instrument in some detail and some outstanding features in the particle data obtained during the first months of operation at altitudes around 1700 km in the northern hemisphere auroral region. 相似文献
819.
820.