全文获取类型
收费全文 | 81491篇 |
免费 | 746篇 |
国内免费 | 1418篇 |
专业分类
测绘学 | 2648篇 |
大气科学 | 5202篇 |
地球物理 | 15572篇 |
地质学 | 32507篇 |
海洋学 | 6412篇 |
天文学 | 15563篇 |
综合类 | 2281篇 |
自然地理 | 3470篇 |
出版年
2022年 | 537篇 |
2021年 | 837篇 |
2020年 | 897篇 |
2019年 | 1019篇 |
2018年 | 6623篇 |
2017年 | 5756篇 |
2016年 | 4650篇 |
2015年 | 1193篇 |
2014年 | 2002篇 |
2013年 | 3126篇 |
2012年 | 3139篇 |
2011年 | 5277篇 |
2010年 | 4448篇 |
2009年 | 5196篇 |
2008年 | 4463篇 |
2007年 | 5093篇 |
2006年 | 2691篇 |
2005年 | 1815篇 |
2004年 | 1941篇 |
2003年 | 1857篇 |
2002年 | 1625篇 |
2001年 | 1340篇 |
2000年 | 1250篇 |
1999年 | 943篇 |
1998年 | 949篇 |
1997年 | 947篇 |
1996年 | 706篇 |
1995年 | 724篇 |
1994年 | 713篇 |
1993年 | 577篇 |
1992年 | 573篇 |
1991年 | 526篇 |
1990年 | 617篇 |
1989年 | 519篇 |
1988年 | 490篇 |
1987年 | 515篇 |
1986年 | 413篇 |
1985年 | 596篇 |
1984年 | 620篇 |
1983年 | 598篇 |
1982年 | 564篇 |
1981年 | 507篇 |
1980年 | 522篇 |
1979年 | 406篇 |
1978年 | 433篇 |
1977年 | 398篇 |
1976年 | 349篇 |
1975年 | 358篇 |
1974年 | 338篇 |
1973年 | 359篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
101.
M.?A.?LevitanEmail author T.?N.?Gelvi K.?V.?Syromyatnikov K.?D.?Chekan 《Geochemistry International》2018,56(4):304-317
Lithofacies zoning is described for the first time for the Neo- and Eopleistocene of the Bering Sea. Four lithofacies sedimentation zones are distinguished: (I) terrigenous; (II) siliceous–terrigenous; (III) siliceous, and (IV) volcanoterrigenous ones. Corresponding maps were treated using Ronov volumetric method to quantify sedimentation parameters for distinguished lithofacies zones (subzones) and types of Pleistocene sediments. It was revealed that terrigenous sediments predominate over other sediments. Accumulation of the terrigenous sediments was more intense (by 1.4 times) in the Neopleistocene than in the Eopleistocene. The sedimentation rate of siliceous sediments of the Bowers Ridge in the Eopleistocene was two times higher than in the Neopleistocene. 相似文献
102.
The Upper Middle Rhine Valley, granted the status of a World Heritage site, is well known for its unique inner narrow valley
of Quaternary age with its historical legacy of numerous medieval castles and old towns. Less known is that this has always
been a risk area of floods and gravitative mass movements. Up to the recent past, mainly ice floods caused enormous damage.
The inhabitants of the valley were well aware that they lived in a risk area, but they had learned to handle the flood hazard.
With the demise of ice floods over the last 40 years, due to climate change and because of the additional heating of the river
water by power plants, the awareness of flood hazards has been much diminished, in contrast to that of potential damage by
rockfalls and landslides which were also much feared in the past, though at the local level only. Still in the people’s memory
is the Kaub catastrophe of March 10, 1876, when 28 persons were killed by a landslide. Nowadays, even minor rockfalls are
a major threat, as they will affect the much-used traffic lines on both banks of the river, in particular the railroads. Therefore,
since 2002, on behalf of German Rail (Deutsche Bahn, DB), all problematic slopes have been protected by costly steel-ring nets, although they are an aesthetic problem by UNESCO
standards. The feeling of absolute safety created among the public is only subjective, though, as planners are well aware
of. Moreover, the impact of modern climate change on slope stability is nearly unknown. Therefore, it is still necessary to
develop a risk map for the narrow valley, with emphasis on gravitational hazards. 相似文献
103.
A. F. Morozov B. N. Khakhaev O. V. Petrov V. I. Gorbachev G. V. Tarkhanov L. D. Tsvetkov Yu. M. Erinchek A. M. Akhmedov V. A. Krupenik K. Yu. Sveshnikova 《Doklady Earth Sciences》2010,435(1):1483-1486
A thick (200 m) rock salt mass covering Late Archean granitoids was exposed for the first time in the Early Proterozoic volcanogenic-sedimentary
formations in the Onega trough of the east Baltic Shield by the Onega parametric well. The mineral composition of salts, their
geochemical features, and the isotopic composition of carbonate carbon and oxygen have been studied. After fluid inclusions
present in salts, their metamorphism temperature and isotopic composition of helium and argon were determined. The obtained
results give evidence of the fact that rock salts and magnesites associated with them were formed in an evaporate basin with
participation of deep crustal processes. The age of the underlying granitoids (2.716 ± 9 Ma) is determined using the Pb—Pb
method. 相似文献
104.
Doklady Earth Sciences - Distribution density functions for the sensitivity of a three-coil sounder are constructed as the weighted mean rock volume between the in-phase surfaces of running... 相似文献
105.
G. S. Ripp A. G. Doroshkevich M. V. Badmatsyrenov N. S. Karmanov 《Geochemistry International》2007,45(6):538-545
The composition and nature of high-Cr minerals in lithic clasts from the carbonatites of the Veseloe occurrence, northern Transbaikalia, were considered. In order to determine their source, the Cr-bearing phases were compared with chromite, magnetite, and rutile from ultrabasic rocks, mantle xenoliths, and eclogites. It was suggested that the xenoclasts studied were formed at great depths, whereas the carbonatites were directly derived from the mantle rather than formed by the crustal differentiation of a silicate-carbonate melt. 相似文献
106.
In this paper we report on the MEM power spectrum analysis of brightness temperature fluctuations observed at 2.8 GHz during the total solar eclipse of 16 February 1980. The observed periodicities range from 3.5 min to 64 min. These periodicities may arise due to spatial and/or temporal variations in the solar radio emission. The observed periodicities imply presence of scale sizes ranging from 70,000 to 600,000 km assuming that the brightness fluctuations arise because of spatial variation only. On the other hand, if these fluctuations are due to temporal variation, the observed periodicities correspond well to predicted modes of solar global oscillations. 相似文献
107.
108.
Natural Hazards - The article was published with the citation “Worni et al. (2012)”. The author group of the article would like readers to know that this information should instead... 相似文献
109.
110.