全文获取类型
收费全文 | 54658篇 |
免费 | 919篇 |
国内免费 | 521篇 |
专业分类
测绘学 | 1329篇 |
大气科学 | 3786篇 |
地球物理 | 10361篇 |
地质学 | 20482篇 |
海洋学 | 5112篇 |
天文学 | 12132篇 |
综合类 | 131篇 |
自然地理 | 2765篇 |
出版年
2022年 | 408篇 |
2021年 | 672篇 |
2020年 | 741篇 |
2019年 | 778篇 |
2018年 | 1656篇 |
2017年 | 1595篇 |
2016年 | 1828篇 |
2015年 | 928篇 |
2014年 | 1705篇 |
2013年 | 3005篇 |
2012年 | 1907篇 |
2011年 | 2447篇 |
2010年 | 2160篇 |
2009年 | 2663篇 |
2008年 | 2299篇 |
2007年 | 2354篇 |
2006年 | 2237篇 |
2005年 | 1496篇 |
2004年 | 1444篇 |
2003年 | 1358篇 |
2002年 | 1370篇 |
2001年 | 1254篇 |
2000年 | 1192篇 |
1999年 | 952篇 |
1998年 | 932篇 |
1997年 | 996篇 |
1996年 | 816篇 |
1995年 | 774篇 |
1994年 | 789篇 |
1993年 | 636篇 |
1992年 | 631篇 |
1991年 | 601篇 |
1990年 | 648篇 |
1989年 | 542篇 |
1988年 | 548篇 |
1987年 | 610篇 |
1986年 | 500篇 |
1985年 | 709篇 |
1984年 | 661篇 |
1983年 | 673篇 |
1982年 | 650篇 |
1981年 | 539篇 |
1980年 | 601篇 |
1979年 | 488篇 |
1978年 | 487篇 |
1977年 | 436篇 |
1976年 | 412篇 |
1975年 | 417篇 |
1974年 | 420篇 |
1973年 | 394篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
M Grande R BrowningN Waltham D ParkerS.K Dunkin B KentB Kellett C.H PerryB Swinyard A PerryJ Feraday C HoweG McBride K PhillipsJ Huovelin P MuhliP.J Hakala O VilhuJ Laukkanen N ThomasD Hughes H AlleyneM Grady R LundinS Barabash D BakerP.E Clark C.D MurrayJ Guest I CasanovaL.C d'Uston S MauriceB Foing D.J Heather V FernandesK Muinonen S.S RussellA Christou C OwenP Charles H KoskinenM Kato K SipilaS Nenonen M HolmstromN Bhandari R ElphicD Lawrence 《Planetary and Space Science》2003,51(6):427-433
The D-CIXS Compact X-ray Spectrometer will provide high quality spectroscopic mapping of the Moon, the primary science target of the ESA SMART-1 mission. D-CIXS consists of a high throughput spectrometer, which will perform spatially localised X-ray fluorescence spectroscopy. It will also carry a solar monitor, to provide the direct calibration needed to produce a global map of absolute lunar elemental abundances, the first time this has been done. Thus it will achieve ground breaking science within a resource envelope far smaller than previously thought possible for this type of instrument, by exploiting two new technologies, swept charge devices and micro-structure collimators. The new technology does not require cold running, with its associated overheads to the spacecraft. At the same time it will demonstrate a radically novel approach to building a type of instrument essential for the BepiColombo mission and potential future planetary science targets. 相似文献
53.
Sediment successions in coastal cliffs around Mezen Bay, southeastern White Sea, record an unusually detailed history of former glaciations, interstadial marine and fluvial events from the Weichselian. A regional glaciation model for the Weichselian is based on new data from the Mezen Bay area and previously published data from adjacent areas. Following the Mikulinian (Eemian) interglacial a shelf‐centred glaciation in the Kara Sea is reflected in proglacial conditions at 100–90 ka. A local ice‐cap over the Timan ridge existed between 75 and 65 ka. Renewed glaciation in the Kara Sea spread southwestwards around 60 ka only, interrupted by a marine inundation, before it advanced to its maximum position at about 55–50 ka. After a prolonged ice‐free period, the Scandinavian ice‐sheet invaded the area from the west and terminated east of Mezen Bay about 17 ka. The previously published evidence of a large ice‐dammed lake in the central Arkhangelsk region, Lake Komi, finds no support in this study. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
54.
55.
Global changes of the solar activity can be expressed by the coronal index that is based upon the total irradiance of the coronal 530.3 nm green line from observations at five stations. Daily mean values of the coronal index of solar activity and other well-correlated solar indices are analyzed for the period 1966–1998 covering over three solar cycles. The significant correlation of this index with the sunspot number and the solar flare index have led to an analytical expression which can reproduce the coronal index of solar activity as a function of these parameters. This expression explains well the existence of the two maxima during the solar cycles taking into account the evolution of the magnetic field that can be expressed by some sinusoidal terms during solar maxima and minima. The accuracy between observed and calculated values of the coronal index on a daily basis reaches the value of 71%. It is concluded that the representative character of the coronal index is preserved even when using daily data and can therefore allow us to study long-term, intermediate and short-term variations for the Sun as a star, in association with different periodical solar–terrestrial phenomena useful for space weather studies. 相似文献
56.
57.
58.
C.S. Botzler J. Snigula R. Bender N. Drory G. Feulner G.J. Hill U. Hopp C. Maraston C. Mendes de Oliveira 《Astrophysics and Space Science》2003,284(2):393-396
The Munich Near-IR Cluster Survey (MUNICS) is a wide-area, medium-deep, photometric survey selected in the K' band. The project's
main scientific aims are the identification of galaxy clusters up to redshifts of unity and the selection of a large sample
of field early-type galaxies up to z < 1.5 for evolutionary studies. We created a Large Scale Structure catalog, using a new structure finding technique specialized
for photometric datasets, that we developed on the basis of a friends-of-friends algorithm. We tested the plausibility of
the resulting galaxy group and cluster catalog with the help of Color-Magnitude Diagrams (CMD), as well as a likelihood- and
Voronoi-approach.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
59.
J.-M. Carquillat N. Ginestet J.-L. Prieur Y. Debernardi 《Monthly notices of the Royal Astronomical Society》2003,346(2):555-564
We present the results of a radial-velocity study of eight Am stars (HD 341, 55822, 61250, 67317, 93991, 162950, 224890 and 225137) observed at Observatoire de Haute-Provence with the CORAVEL instrument. We find that these systems are single-line spectroscopic binaries whose orbital elements are determined for the first time. 相似文献
60.
Cristiano B. Cosmovici Vojko Bratina Gottfried Schwarz Gianpaolo Tozzi Michael J. Mumma Roberto Stalio 《Astrophysics and Space Science》2006,301(1-4):135-143
We report here on unique post-perihelion (2.3 AU) measurements of Comet Hale-Bopp in the FUV-range (950–1250 Å) by means of the UVSTAR spectrometer from the space shuttle with the main purpose of searching for argon and other FUV emitters. New methods for separating the strong airglow emission at shuttle altitudes are here discussed in detail. Due to our low resolution (15 Å) and S/N ratio the possible rocket-borne detection of argon near perihelion (0.9 AU) could not be confirmed. New species as N2 are suspected but difficult to separate from the strong airglow emission at shuttle altitudes. From the Lyα brightness (1.30± 0.08 kRy) a water production rate Q = 5.9 ± 0.4 × 1029 molecules s?1 could be derived and compared with other post-perihelion observations. 相似文献