全文获取类型
收费全文 | 2482篇 |
免费 | 7篇 |
国内免费 | 6篇 |
专业分类
航空 | 1220篇 |
航天技术 | 997篇 |
综合类 | 5篇 |
航天 | 273篇 |
出版年
2021年 | 13篇 |
2019年 | 14篇 |
2018年 | 41篇 |
2017年 | 34篇 |
2016年 | 25篇 |
2015年 | 11篇 |
2014年 | 50篇 |
2013年 | 62篇 |
2012年 | 50篇 |
2011年 | 87篇 |
2010年 | 62篇 |
2009年 | 105篇 |
2008年 | 149篇 |
2007年 | 62篇 |
2006年 | 46篇 |
2005年 | 62篇 |
2004年 | 71篇 |
2003年 | 91篇 |
2002年 | 46篇 |
2001年 | 101篇 |
2000年 | 45篇 |
1999年 | 86篇 |
1998年 | 85篇 |
1997年 | 62篇 |
1996年 | 63篇 |
1995年 | 88篇 |
1994年 | 97篇 |
1993年 | 37篇 |
1992年 | 59篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 56篇 |
1988年 | 20篇 |
1987年 | 35篇 |
1986年 | 21篇 |
1985年 | 74篇 |
1984年 | 42篇 |
1983年 | 47篇 |
1982年 | 55篇 |
1981年 | 77篇 |
1980年 | 26篇 |
1979年 | 24篇 |
1978年 | 22篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 18篇 |
1974年 | 12篇 |
1972年 | 17篇 |
1969年 | 13篇 |
1966年 | 8篇 |
排序方式: 共有2495条查询结果,搜索用时 15 毫秒
91.
Ts.P. Dachev B.T. Tomov Yu.N. Matviichuk Pl.G. Dimitrov N.G. Bankov G. Reitz G. Horneck D.-P. Häder M. Lebert M. Schuster 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Space radiation has been monitored successfully using the Radiation Risks Radiometer-Dosimeter (R3D) installed at the ESA EXPOSE-R (R3DR) facility outside of the Russian Zvezda module of the International Space Station (ISS) between March 2009 and January 2011. R3DR is a Liulin type spectrometer–dosimeter with a single Si PIN detector 2 cm2 of area and 0.3 mm thick. The R3DR instrument accumulated about 2 million measurements of the absorbed dose rate and flux of 10 s resolution. The total external and internal shielding before the detector of R3DR device is 0.41 g cm−2. The calculated stopping energy of normally incident particles to the detector is 0.78 MeV for electrons and 15.8 MeV for protons. After the Coronal Mass Ejection (CME) at 09:54 UTC on 3 April 2010, a shock was observed at the ACE spacecraft at 0756 UTC on 5 April, which led to a sudden impulse on Earth at 08:26 UTC. Nevertheless, while the magnetic substorms on 5 and 6 of April were moderate; the second largest in history of GOES fluence of electrons with energy >2 MeV was measured. The R3DR data show a relatively small amount of relativistic electrons on 5 April. The maximum dose rate of 2323 μGy day−1 was reached on 7 April; by 9 April, a dose of 6600 μGy was accumulated. By the end of the period on 7 May 2010 a total dose of 11,587 μGy was absorbed. Our data were compared with AE-8 MIN, CRESS and ESA-SEE1 models using SPENVIS and with similar observations on American, Japanese and Russian satellites. 相似文献
92.
N. Wichaipanich P. Supnithi T. Tsugawa T. Maruyama T. Nagatsuma 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
In this work, the foF2 and hmF2 parameters at the conjugate points near the magnetic equator of Southeast Asia are studied and compared with the International Reference Ionosphere (IRI) model. Three ionosondes are installed nearly along the magnetic meridian of 100°E; one at the magnetic equator, namely Chumphon (10.72°N, 99.37°E, dip angle 3.0°N), and the other two at the magnetic conjugate points, namely Chiang Mai (18.76°N, 98.93°E, dip angle 12.7°N) and Kototabang (0.2°S, 100.30°E, dip angle 10.1°S). The monthly hourly medians of the foF2 and hmF2 parameters are calculated and compared with the predictions obtained from the IRI-2007 model from January 2004 to February 2007. Our results show that: the variations of foF2 and hmF2 predicted by the IRI-2007 model generally show the similar feature to the observed data. Both parameters generally show better agreement with the IRI predictions during daytime than during nighttime. For foF2, most of the results show that the IRI model overestimates the observed foF2 at the magnetic equator (Chumphon), underestimates at the northern crest (Chiang Mai) and is close to the measured ones at the southern crest of the EIA (Kototabang). For hmF2, the predicted hmF2 values are close to the hmF2(M3000F2OBS) during daytime. During nighttime, the IRI model gives the underestimation at the magnetic equator and the overestimation at both EIA crests. The results are important for the future improvements of the IRI model for foF2 and hmF2 over Southeast Asia region. 相似文献
93.
E.S. Seo T. Anderson D. Angelaszek S.J. Baek J. Baylon M. Buénerd M. Copley S. Coutu L. Derome B. Fields M. Gupta J.H. Han I.J. Howley H.G. Huh Y.S. Hwang H.J. Hyun I.S. Jeong D.H. Kah K.H. Kang D.Y. Kim H.J. Kim K.C. Kim M.H. Kim K. Kwashnak J. Lee M.H. Lee J.T. Link L. Lutz A. Malinin A. Menchaca-Rocha J.W. Mitchell S. Nutter O. Ofoha H. Park I.H. Park J.M. Park P. Patterson J.R. Smith J. Wu Y.S. Yoon 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The Cosmic Ray Energetics And Mass (CREAM) instrument is configured with a suite of particle detectors to measure TeV cosmic-ray elemental spectra from protons to iron nuclei over a wide energy range. The goal is to extend direct measurements of cosmic-ray composition to the highest energies practical, and thereby have enough overlap with ground based indirect measurements to answer questions on cosmic-ray origin, acceleration and propagation. The balloon-borne CREAM was flown successfully for about 161 days in six flights over Antarctica to measure elemental spectra of Z = 1–26 nuclei over the energy range 1010 to >1014 eV. Transforming the balloon instrument into ISS-CREAM involves identification and replacement of components that would be at risk in the International Space Station (ISS) environment, in addition to assessing safety and mission assurance concerns. The transformation process includes rigorous testing of components to reduce risks and increase survivability on the launch vehicle and operations on the ISS without negatively impacting the heritage of the successful CREAM design. The project status, including results from the ongoing analysis of existing data and, particularly, plans to increase the exposure factor by another order of magnitude utilizing the International Space Station are presented. 相似文献
94.
David Blake David Vaniman Cherie Achilles Robert Anderson David Bish Tom Bristow Curtis Chen Steve Chipera Joy Crisp David Des?Marais Robert T. Downs Jack Farmer Sabrina Feldman Mark Fonda Marc Gailhanou Hongwei Ma Doug W. Ming Richard V. Morris Philippe Sarrazin Ed Stolper Allan Treiman Albert Yen 《Space Science Reviews》2012,170(1-4):341-399
A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity’s 1-Mars-year nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin’s angular range of 5° to 50° 2θ with <0.35° 2θ resolution is sufficient to identify and quantify virtually all minerals. CheMin’s XRF requirement was descoped for technical and budgetary reasons. However, X-ray energy discrimination is still required to separate Co?Kα from Co?Kβ and Fe?Kα photons. The X-ray energy-dispersive histograms (EDH) returned along with XRD for instrument evaluation should be useful in identifying elements Z>13 that are contained in the sample. The CheMin XRD is equipped with internal chemical and mineralogical standards and 27 reusable sample cells with either Mylar? or Kapton? windows to accommodate acidic-to-basic environmental conditions. The CheMin flight model (FM) instrument will be calibrated utilizing analyses of common samples against a demonstration-model (DM) instrument and CheMin-like laboratory instruments. The samples include phyllosilicate and sulfate minerals that are expected at Gale crater on the basis of remote sensing observations. 相似文献
95.
96.
Grasset O. Castillo-Rogez J. Guillot T. Fletcher L. N. Tosi F. 《Space Science Reviews》2017,212(1-2):835-875
Space Science Reviews - Space exploration and ground-based observations have provided outstanding evidence of the diversity and the complexity of the outer solar system. This work presents our... 相似文献
97.
S. Mühlbachler D. Langmayr A.T.Y. Lui N.V. Erkaev I.V. Alexeev P.W. Daly H.K. Biernat 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
This study presents several observations of the Cluster spacecraft on September 24, 2003 around 15:10 UT, which show necessary prerequisites and consequences for the formation of the so-called modified-two-stream instability (MTSI). Theoretical studies suggest that the plasma is MTSI unstable if (1) a relative drift of electrons and ions is present, which exceeds the Alfvèn speed, and (2) this relative drift or current is in the cross-field direction. As consequences of the formation of a MTSI one expects to observe (1) a field-aligned electron beam, (2) heating of the plasma, and (3) an enhancement in the B-wave spectrum at frequencies in the range of the lower-hybrid-frequency (LHF). In this study we use prime parameter data of the CIS and PEACE instruments onboard the Cluster spacecraft to verify the drift velocities of ions and electrons, FGM data to calculate the expected LHF and Alfvèn velocity, and the direction of the current. The B-wave spectrum is recorded by the STAFF instrument of Cluster. Finally, a field aligned beam of electrons is observed by 3D measurements of the IES instrument of the RAPID unit. Observations are verified using a theoretical model showing the build-up of a MTSI under the given circumstances. 相似文献
98.
J. Watermann P. Stauning H. Lühr P.T. Newell F. Christiansen K. Schlegel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
We examined some 75 observations from the low-altitude Earth orbiting DMSP, Ørsted and CHAMP satellites which were taken in the region of the nominal cusp. Our objective was to determine whether the actually observed cusp locations as inferred from magnetosheath-like particle precipitation (“particle cusp”) and intense small-scale magnetic field variations (“current cusp”), respectively, were identical and were consistent with the statistically expected latitude of the cusp derived from a huge number of charged particle spectrograms (“statistical cusp”). 相似文献
99.
W.D. Apel J.C. Arteaga-Velázquez K. Bekk M. Bertaina J. Blümer H. Bozdog I.M. Brancus E. Cantoni A. Chiavassa F. Cossavella K. Daumiller V. de Souza F. Di Pierro P. Doll R. Engel J. Engler M. Finger B. Fuchs D. Fuhrmann H.J. Gils R. Glasstetter C. Grupen A. Haungs D. Heck J.R. Hörandel D. Huber T. Huege K.-H. Kampert D. Kang H.O. Klages K. Link P. Łuczak M. Ludwig H.J. Mathes H.J. Mayer M. Melissas J. Milke B. Mitrica C. Morello J. Oehlschläger S. Ostapchenko N. Palmieri M. Petcu T. Pierog H. Rebel M. Roth H. Schieler S. Schoo F.G. Schröder O. Sima 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
100.
P. Alexander D. Luna A. de la Torre P. Llamedo T. Schmidt J. Wickert 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The Global Positioning System (GPS) Radio Occultation (RO) technique has global coverage and is capable of generating high vertical resolution temperature profiles of the upper troposphere and lower stratosphere with sub-Kelvin accuracy and long-term stability, regardless of weather conditions. In this work, we take advantage of the anomalously high density of occultation events at the eastern side of the highest Andes Mountains during the initial mission months of COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate). This region is well-known for its high wave activity. We choose to study two pairs of GPS RO, both containing two occultations that occurred close in time and space. One pair shows significant differences between both temperature profiles. Numerical simulations with a mesoscale model were performed, in order to understand this discrepancy. It is attributed to the presence of a horizontal inhomogeneous structure caused by gravity waves. 相似文献