全文获取类型
收费全文 | 885篇 |
免费 | 33篇 |
国内免费 | 21篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 127篇 |
地球物理 | 191篇 |
地质学 | 364篇 |
海洋学 | 30篇 |
天文学 | 191篇 |
综合类 | 4篇 |
自然地理 | 24篇 |
出版年
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 23篇 |
2015年 | 28篇 |
2014年 | 28篇 |
2013年 | 43篇 |
2012年 | 41篇 |
2011年 | 42篇 |
2010年 | 34篇 |
2009年 | 40篇 |
2008年 | 48篇 |
2007年 | 31篇 |
2006年 | 35篇 |
2005年 | 37篇 |
2004年 | 31篇 |
2003年 | 24篇 |
2002年 | 28篇 |
2001年 | 19篇 |
2000年 | 22篇 |
1999年 | 19篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 10篇 |
1972年 | 6篇 |
1960年 | 4篇 |
排序方式: 共有939条查询结果,搜索用时 31 毫秒
911.
Zeming Zhang Yilin Xiao Jochen Hoefs J. G. Liou Klaus Simon 《Contributions to Mineralogy and Petrology》2006,152(4):421-441
The main hole (MH) of the Chinese Continental Scientific Drilling Project (CCSD) in southern Sulu has penetrated into an ultrahigh-pressure (UHP) metamorphic rock slice which consists of orthogneiss, paragneiss, eclogite, ultramafic rock and minor schist. Recovered eclogites have a UHP metamorphic mineral assemblage of garnet + omphacite + rutile ± phengite ± kyanite ± coesite ± epidote. Ultramafic rocks contain garnet + olivine + clinopyroxene + orthopyroxene ± Ti-clinohumite ± phlogopite. Gneisses and schists contain an amphibolite-facies paragenesis, but their zircons have coesite, garnet, omphacite (or jadeite) and phengite inclusions, indicating that eclogites and gneisses have been subjected to in situ UHP metamorphism. Using available geothermobarometers, P–T estimates of 3.1–4.4 GPa and 678–816°C for eclogites were obtained. If surface outcrops and neighboring shallow drill holes are considered together, we suggest that a huge supracrustal rock slab (> 50 km long × 100 km wide × 5 km deep) was subducted to a depth > 100 km and then exhumed to the surface. The depth interval (0–2,050 m) of the CCSD-MH can be divided into six lithological units. Unit 1 consists of alternating layers of quartz-rich and rutile-rich eclogites, with thin interlayers of gneiss and schist. Eclogites of unit 1 are characterized by Nb, Ta, Sr and Ti depletions, low Mg number and general LREE enrichment. Unit 2 comprises rutile- and ilmenite-rich eclogite and minor “normal” eclogite and is characterized by high TiO2, total Fe, V, Co and Sr, and very low SiO2, alkali, Zr, Ba, Nb, Ta and total REE contents, and LREE-depleted REE patterns with slightly positive Eu anomalies. Unit 3 contains ultramafic rock and minor MgO-rich eclogite. Protoliths of UHP rocks from units 1, 2 and 3 represent a layered mafic to ultramafic intrusion at crustal depth. Units 4 and 6 consist of interlayered eclogite and paragneiss; the eclogites are characterized by Th, U, Nb, Ta and Ti depletion and K enrichment and LREE-enriched REE patterns. Paragneisses show Nb, Ta, Sr and Ti depletions and LREE-enriched REE patterns occasionally with slightly negative Eu anomalies, indicating that their protoliths represent metamorphic supracrustal series. Unit 5 consists mainly of orthogneisses, showing distinct Nb, Ta, Sr and Ti depletions, and LREE-enriched REE patterns with pronounced negative Eu anomalies, suggesting granitic protoliths. In conclusion it is proposed that the southern Sulu UHP belt consists of a series of meta-supracrustal rocks, a layered mafic–ultramafic complex and granites. 相似文献
912.
913.
914.
Between 1 January 1980 and 28 July 1981, a series of large earthquakes with body-wave magnitudes around 7, took place along the western segment of the Alpide belt. The sequence started in the Azores and migrated eastward along the belt at a rate of about 4400 km/yr with consecutive large events in northern Algeria, southern Italy, southern Greece and Iran. Two different methods are employed to identify similar series and corresponding migration velocities during earlier time periods of this century. The data set used contains all earthquakes with body-wave magnitudes larger than 6.3 and covers the time interval 1901–81. The concept of linear migration is tested for eastward and/or westward propagation, considering high migration velocities from 1600 to 11 000 km/yr. Results obtained are not homogeneous with respect to the two opposite migration directions, west-east and east-west, and we interpret this as a net drift of earthquake activity from the west to the east. Our efforts here are concentrated on analysis of observational data and on estabilishing the uniqueness of migration patterns. Because of the complexity of the tectonic system in question, we did not attempt to establish a mechanism explaining the migration of the observed earthquake sequences. 相似文献
915.
Dr. Klaus Rother 《GeoJournal》1986,13(1):27-35
In the Mediterranean area modern economic development is concentrating more and more on the favourably situated coastal plains. The coastal plains of Calabria, which are examined on the basis of land utilization mapping, form, in this backward S Italian region, individually characteristic areas of different levels of agrarian development. Areas with insufficient aid and stagnating development and those with a strong initial developmental impulse and hesitant further development, stand face-to-face with areas with a continuous upward trend. The latter fit into the ranks of those consolidated agricultural regions of S Italy in which government aid and private initiative are multifariously intertwined and together support the process of development. Up to now, however, the different non-agricultural interests have impeded the continuing progress of the process more and more and given rise to awkward land utilization conflicts. Through settlement expansion, the building of transport facilities and ports for industrial zones as well as tourism, the use of land for agriculture is, to an increasing extent, being taken away so that regional planning seems imperative. 相似文献
916.
917.
Summary Vertical temperature traces in the north-western Mediteranean show remarkably leafy structures at depths between 100 m and 300 m. The individual layers are stable over several days. Their horizontal extension is larger than 20 nm. The thickness amounts to 25–50 m. It is suggested that these interleavings of slightly different water masses are due to lateral mixing processes in the vicinity of the working area.
Inversionen unterhalb der Sprungschicht im nordwestlichen Mittelmeer
Zusammenfassung Temperaturprofile im nordwestlichen Mittelmeer weisen eine auffällig blättrige Struktur in Tiefen von 100–300 m auf. Die einzelnen Schichten sind über mehrere TAge stabil. Ihre horizontale Ausdehnung ist größer als 20 sm. Die vertikale Mächtigkeit beträgt 25–50 m. Es wird angenommen, daß die schichtförmigen Einschübe schwach unterschiedlicher Wassermassen durch Vermischung in der Umgebung des Arbeitsgebietes entstanden sind.
Inversions du gradient de température au-dessous de la thermocline dans le Nord Ouest de la Méditerranée
Résumé Les tracés verticaux de la température, dans le Nord Ouest de la Méditerranée ont des structures remarquablement superposées en minces feuillets, à des profondeurs comprises entre 100 et 300 mètres. Les couches individuelles sont stables pendant plusieurs jours. Elles s'étendent horizontalement sur plus de 20 milles nautiques. Leur épaisseur atteint 25 à 50 mètres. On suppose que ces superpositions de masses d'eau légèrement différentes sont dues à des processus de mélange latéral au voisinage de la région d'opération.相似文献
918.
919.
920.