全文获取类型
收费全文 | 69篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
航空 | 45篇 |
航天技术 | 11篇 |
综合类 | 1篇 |
航天 | 14篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2018年 | 1篇 |
2017年 | 10篇 |
2015年 | 3篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 6篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有71条查询结果,搜索用时 62 毫秒
51.
Sources of organic matter and inorganic tracers on Jupiter, including solar UV photolysis, lightning discharges, and convective quenching of hot gases from the lower atmosphere, are reviewed in light of Earth-based and Voyager data with the purpose of predicting the tropospheric steady-state abundances and vertical distributions of HCN, CH2O, and other species.It is concluded that a steady-state mole fraction of HCN in the Jovian troposphere of only 10-12 could be maintained by vertical transport of hot gases from the deep atmosphere. The observed HCN abundance (roughly XHCN = 10-9) appears to be due to photochemical reactions.After HCN, the most abundant organic disequilibrium species in the troposphere is probably C2H6, derived from direct photolysis of CH4 at high altitudes, with a mole fracton of 10-10 at the H2O cloud level. Inorganic tracers of disequilibrium processes are also briefly summarized. 相似文献
52.
The Mercury Dual Imaging System on the MESSENGER Spacecraft 总被引:1,自引:0,他引:1
S. Edward Hawkins III John D. Boldt Edward H. Darlington Raymond Espiritu Robert E. Gold Bruce Gotwols Matthew P. Grey Christopher D. Hash John R. Hayes Steven E. Jaskulek Charles J. Kardian Jr. Mary R. Keller Erick R. Malaret Scott L. Murchie Patricia K. Murphy Keith Peacock Louise M. Prockter R. Alan Reiter Mark S. Robinson Edward D. Schaefer Richard G. Shelton Raymond E. Sterner II Howard W. Taylor Thomas R. Watters Bruce D. Williams 《Space Science Reviews》2007,131(1-4):247-338
The Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft will provide critical measurements tracing Mercury’s origin
and evolution. MDIS consists of a monochrome narrow-angle camera (NAC) and a multispectral wide-angle camera (WAC). The NAC
is a 1.5° field-of-view (FOV) off-axis reflector, coaligned with the WAC, a four-element refractor with a 10.5° FOV and 12-color
filter wheel. The focal plane electronics of each camera are identical and use a 1,024×1,024 Atmel (Thomson) TH7888A charge-coupled
device detector. Only one camera operates at a time, allowing them to share a common set of control electronics. The NAC and
the WAC are mounted on a pivoting platform that provides a 90° field-of-regard, extending 40° sunward and 50° anti-sunward
from the spacecraft +Z-axis—the boresight direction of most of MESSENGER’s instruments. Onboard data compression provides capabilities for pixel
binning, remapping of 12-bit data into 8 bits, and lossless or lossy compression. MDIS will acquire four main data sets at
Mercury during three flybys and the two-Mercury-solar-day nominal mission: a monochrome global image mosaic at near-zero emission
angles and moderate incidence angles, a stereo-complement map at off-nadir geometry and near-identical lighting, multicolor
images at low incidence angles, and targeted high-resolution images of key surface features. These data will be used to construct
a global image base map, a digital terrain model, global maps of color properties, and mosaics of high-resolution image strips.
Analysis of these data will provide information on Mercury’s impact history, tectonic processes, the composition and emplacement
history of volcanic materials, and the thickness distribution and compositional variations of crustal materials. This paper
summarizes MDIS’s science objectives and technical design, including the common payload design of the MDIS data processing
units, as well as detailed results from ground and early flight calibrations and plans for Mercury image products to be generated
from MDIS data. 相似文献
53.
Panning Mark P. Lognonné Philippe Bruce Banerdt W. Garcia Raphaël Golombek Matthew Kedar Sharon Knapmeyer-Endrun Brigitte Mocquet Antoine Teanby Nick A. Tromp Jeroen Weber Renee Beucler Eric Blanchette-Guertin Jean-Francois Bozdağ Ebru Drilleau Mélanie Gudkova Tamara Hempel Stefanie Khan Amir Lekić Vedran Murdoch Naomi Plesa Ana-Catalina Rivoldini Atillio Schmerr Nicholas Ruan Youyi Verhoeven Olivier Gao Chao Christensen Ulrich Clinton John Dehant Veronique Giardini Domenico Mimoun David Thomas Pike W. Smrekar Sue Wieczorek Mark Knapmeyer Martin Wookey James 《Space Science Reviews》2017,211(1-4):611-650
Space Science Reviews - The InSight lander will deliver geophysical instruments to Mars in 2018, including seismometers installed directly on the surface (Seismic Experiment for Interior Structure,... 相似文献
54.
With the objective of reducing the flight cost and the amount of polluting emissions released in the atmosphere, a new optimization algorithm considering the climb, cruise and descent phases is presented for the reference vertical flight trajectory. The selection of the reference vertical navigation speeds and altitudes was solved as a discrete combinatory problem by means of a graphtree passing through nodes using the beam search optimization technique. To achieve a compromise between the execution time and the algorithm's ability to find the global optimal solution, a heuristic methodology introducing a parameter called ‘‘optimism coefficient was used in order to estimate the trajectory's flight cost at every node. The optimal trajectory cost obtained with the developed algorithm was compared with the cost of the optimal trajectory provided by a commercial flight management system(FMS). The global optimal solution was validated against an exhaustive search algorithm(ESA), other than the proposed algorithm. The developed algorithm takes into account weather effects, step climbs during cruise and air traffic management constraints such as constant altitude segments, constant cruise Mach, and a pre-defined reference lateral navigation route. The aircraft fuel burn was computed using a numerical performance model which was created and validated using flight test experimental data. 相似文献
55.
John O. Goldsten Edgar A. Rhodes William V. Boynton William C. Feldman David J. Lawrence Jacob I. Trombka David M. Smith Larry G. Evans Jack White Norman W. Madden Peter C. Berg Graham A. Murphy Reid S. Gurnee Kim Strohbehn Bruce D. Williams Edward D. Schaefer Christopher A. Monaco Christopher P. Cork J. Del Eckels Wayne O. Miller Morgan T. Burks Lisle B. Hagler Steve J. DeTeresa Monika C. Witte 《Space Science Reviews》2007,131(1-4):339-391
A Gamma-Ray and Neutron Spectrometer (GRNS) instrument has been developed as part of the science payload for NASA’s Discovery
Program mission to the planet Mercury. Mercury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) launched
successfully in 2004 and will journey more than six years before entering Mercury orbit to begin a one-year investigation.
The GRNS instrument forms part of the geochemistry investigation and will yield maps of the elemental composition of the planet
surface. Major elements include H, O, Na, Mg, Si, Ca, Ti, Fe, K, and Th. The Gamma-Ray Spectrometer (GRS) portion detects
gamma-ray emissions in the 0.1- to 10-MeV energy range and achieves an energy resolution of 3.5 keV full-width at half-maximum
for 60Co (1332 keV). It is the first interplanetary use of a mechanically cooled Ge detector. Special construction techniques provide
the necessary thermal isolation to maintain the sensor’s encapsulated detector at cryogenic temperatures (90 K) despite the
intense thermal environment. Given the mission constraints, the GRS sensor is necessarily body-mounted to the spacecraft,
but the outer housing is equipped with an anticoincidence shield to reduce the background from charged particles. The Neutron
Spectrometer (NS) sensor consists of a sandwich of three scintillation detectors working in concert to measure the flux of
ejected neutrons in three energy ranges from thermal to ∼7 MeV. The NS is particularly sensitive to H content and will help
resolve the composition of Mercury’s polar deposits. This paper provides an overview of the Gamma-Ray and Neutron Spectrometer
and describes its science and measurement objectives, the design and operation of the instrument, the ground calibration effort,
and a look at some early in-flight data. 相似文献
56.
Christensen Philip R. Jakosky Bruce M. Kieffer Hugh H. Malin Michael C. McSween Harry Y. Nealson Kenneth Mehall Greg L. Silverman Steven H. Ferry Steven Caplinger Michael Ravine Michael 《Space Science Reviews》2004,110(1-2):85-130
The Thermal Emission Imaging System (THEMIS) on 2001 Mars Odyssey will investigate the surface mineralogy and physical properties of Mars using multi-spectral thermal-infrared images in nine wavelengths centered from 6.8 to 14.9 μm, and visible/near-infrared images in five bands centered from 0.42 to 0.86 μm. THEMIS will map the entire planet in both day and night multi-spectral infrared images at 100-m per pixel resolution, 60% of the planet in one-band visible images at 18-m per pixel, and several percent of the planet in 5-band visible color. Most geologic materials, including carbonates, silicates, sulfates, phosphates, and hydroxides have strong fundamental vibrational absorption bands in the thermal-infrared spectral region that provide diagnostic information on mineral composition. The ability to identify a wide range of minerals allows key aqueous minerals, such as carbonates and hydrothermal silica, to be placed into their proper geologic context. The specific objectives of this investigation are to: (1) determine the mineralogy and petrology of localized deposits associated with hydrothermal or sub-aqueous environments, and to identify future landing sites likely to represent these environments; (2) search for thermal anomalies associated with active sub-surface hydrothermal systems; (3) study small-scale geologic processes and landing site characteristics using morphologic and thermophysical properties; and (4) investigate polar cap processes at all seasons. THEMIS follows the Mars Global Surveyor Thermal Emission Spectrometer (TES) and Mars Orbiter Camera (MOC) experiments, providing substantially higher spatial resolution IR multi-spectral images to complement TES hyperspectral (143-band) global mapping, and regional visible imaging at scales intermediate between the Viking and MOC cameras. The THEMIS uses an uncooled microbolometer detector array for the IR focal plane. The optics consists of all-reflective, three-mirror anastigmat telescope with a 12-cm effective aperture and a speed of f/1.6. The IR and visible cameras share the optics and housing, but have independent power and data interfaces to the spacecraft. The IR focal plane has 320 cross-track pixels and 240 down-track pixels covered by 10 ~1-μm-bandwidth strip filters in nine different wavelengths. The visible camera has a 1024×1024 pixel array with 5 filters. The instrument weighs 11.2 kg, is 29 cm by 37 cm by 55 cm in size, and consumes an orbital average power of 14 W. 相似文献
57.
The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) on the New Horizons Mission
Ralph L. McNutt Jr. Stefano A. Livi Reid S. Gurnee Matthew E. Hill Kim A. Cooper G. Bruce Andrews Edwin P. Keath Stamatios M. Krimigis Donald G. Mitchell Barry Tossman Fran Bagenal John D. Boldt Walter Bradley William S. Devereux George C. Ho Stephen E. Jaskulek Thomas W. LeFevere Horace Malcom Geoffrey A. Marcus John R. Hayes G. Ty Moore Nikolaos P. Paschalidis Mark E. Perry Bruce D. Williams Paul Wilson IV Lawrence E. Brown Martha B. Kusterer Jon D. Vandegriff 《Space Science Reviews》2009,145(3-4):381-381
58.
Daniel B. Reisenfeld Roger C. Wiens Bruce L. Barraclough John T. Steinberg Marcia Neugebauer Jim Raines Thomas H. Zurbuchen 《Space Science Reviews》2013,175(1-4):125-164
We describe the Genesis mission solar-wind sample collection period and the solar wind conditions at the L1 point during this 2.3-year period. In order to relate the solar wind samples to solar composition, the conditions under which the samples were collected must be understood in the context of the long-term solar wind. We find that the state of the solar wind was typical of conditions over the past four solar cycles. However, Genesis spent a relatively large fraction of the time in coronal-hole flow as compared to what might have been expected for the declining phase of the solar cycle. Data from the Solar Wind Ion Composition Spectrometer (SWICS) on the Advanced Composition Explorer (ACE) are used to determine the effectiveness of the Genesis solar-wind regime selection algorithm. The data collected by SWICS confirm that the Genesis algorithm successfully separated and collected solar wind regimes having distinct solar origins, particularly in the case of the coronal hole sample. The SWICS data also demonstrate that the different regimes are elementally fractionated. When compared with Ulysses composition data from the previous solar cycle, we find a similar degree of fractionation between regimes as well as fractionation relative to the average photospheric composition. The Genesis solar wind samples are under long-term curation at NASA Johnson Space Center so that as sample analysis techniques evolve, pristine solar wind samples will be available to the scientific community in the decades to come. This article and a companion paper (Wiens et al. 2013, this issue) provide post-flight information necessary for the analysis of the Genesis array and foil solar wind samples and the Genesis solar wind ion concentrator samples, and thus serve to complement the Space Science Review volume, The Genesis Mission (v. 105, 2003). 相似文献
59.
Paul R. Mahaffy Mehdi Benna Todd King Daniel N. Harpold Robert Arvey Michael Barciniak Mirl Bendt Daniel Carrigan Therese Errigo Vincent Holmes Christopher S. Johnson James Kellogg Patrick Kimvilakani Matthew Lefavor Jerome Hengemihle Ferzan Jaeger Eric Lyness John Maurer Anthony Melak Felix Noreiga Marvin Noriega Kiran Patel Benito Prats Eric Raaen Florence Tan Edwin Weidner Cynthia Gundersen Steven Battel Bruce P. Block Ken Arnett Ryan Miller Curt Cooper Charles Edmonson J. Thomas Nolan 《Space Science Reviews》2015,196(1-4):49-77
60.
We present a methodology that provides traceable analysis from stakeholders’ needs to prioritized goals for human space exploration. We first construct a network to represent the stakeholder environment of NASA’s human exploration efforts, then assess the intensity of these stakeholder needs, and build a numerical model to represent the flow of value in the network. The underlying principle is that as a rational actor, NASA should invest its resources in creating outputs that provide the greatest return of support to it. We showcase this methodology, seeded with test data, the results of which suggests that the most important outputs of the exploration endeavor are human and robotic exploration firsts and science data, but also include funding to the science community, providing interesting NASA mission event content directly to the public and to the media, and commercial contracts. We propose that goals should be structured to ensure these value outputs, and be written in such as way as to convey the subsequent creation of value in the network. The goals derived in this manner suggest that the majority of the value created by human space exploration derives from campaign level design, rather than from operation of transportation elements. There would be higher assurance that these value outputs would be delivered if a responsible official or entity within the exploration function was specifically tasked with ensuring stakeholder value creation. 相似文献