全文获取类型
收费全文 | 3623篇 |
免费 | 646篇 |
国内免费 | 2366篇 |
专业分类
测绘学 | 74篇 |
大气科学 | 2篇 |
地球物理 | 195篇 |
地质学 | 5779篇 |
海洋学 | 202篇 |
天文学 | 2篇 |
综合类 | 286篇 |
自然地理 | 95篇 |
出版年
2024年 | 28篇 |
2023年 | 116篇 |
2022年 | 143篇 |
2021年 | 170篇 |
2020年 | 101篇 |
2019年 | 159篇 |
2018年 | 110篇 |
2017年 | 100篇 |
2016年 | 113篇 |
2015年 | 130篇 |
2014年 | 242篇 |
2013年 | 222篇 |
2012年 | 291篇 |
2011年 | 299篇 |
2010年 | 245篇 |
2009年 | 233篇 |
2008年 | 224篇 |
2007年 | 218篇 |
2006年 | 198篇 |
2005年 | 208篇 |
2004年 | 240篇 |
2003年 | 220篇 |
2002年 | 194篇 |
2001年 | 210篇 |
2000年 | 140篇 |
1999年 | 173篇 |
1998年 | 171篇 |
1997年 | 199篇 |
1996年 | 227篇 |
1995年 | 210篇 |
1994年 | 229篇 |
1993年 | 189篇 |
1992年 | 194篇 |
1991年 | 145篇 |
1990年 | 102篇 |
1989年 | 106篇 |
1988年 | 25篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1982年 | 6篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1972年 | 5篇 |
1949年 | 4篇 |
1946年 | 4篇 |
1942年 | 4篇 |
1941年 | 4篇 |
排序方式: 共有6635条查询结果,搜索用时 0 毫秒
1.
2.
B.K.Sharma A.M.Bhola 《《幕》》2004,27(2):119-124
The metasediments in the Chamba region experienced three phases of deformation: DF1, DF2 and DF3.Folded quartz veins are co-folded with the F2 crenulation folds. Their geometric and tectonic significance is studied by microstructures and shortening adjacent to the discrete crenulation cleavage, S2. Microstructures of folded vein segments, their geometric changes and truncation to cleavage (S2) are mainly due to pressure-solution phenomena and the estimated volume loss from reconstructed vein segments range from 16 to 25.5%,which is closely related to volume decrease (26%) calculated from the polydeformed slates of North Wales areas. 相似文献
3.
谈谈现代地质学的思维结构吴俊华,袁训红(江西地质科学研究所南昌向塘330201)OntheThinkingStructureofModernGeologyWuJunhua;YuenXuntong(JiangxiInstituteofGeology)1... 相似文献
4.
DomenicoRio IsabellaPremoliSilva LucaCapraro 《《幕》》2003,26(3):259-263
The construction of the Geologic Time Scale (GTS) is a titanic scientific challenge that has been under way for two centuries and will require much dedicated effort in the future. Italy preserves a paramount stratigraphic record of Mesozoic and Cenozoic marine sediments that have been significant in the development of the modern GTS. The Italian stratigraphic record has been histori-cally important in introducing and defining the standard Chronostratigraphic Units (CUs) of the Neogene and Quaternary. Pelagic successions from Northern Apen-nines and Southern Alps have been used in the seventies for integrating the late Cretaceous-Paleogene Geomag-netic Polarity Time Scale (GPTS) with planktonic microfossil biostratieraohv and standard CUs. This was a major contribution to the construction of a new gener-ation of GTS based on integrated magnetobiochronol-ogy. The middle Miocene to early Pleistocene marinerecord from Sicily and southern Italy has been funda-mental for establishing the recently developed Astro-nomical Time Scale (ATS). In prospect, there are many potentials still to be exploited in the Italian marine stratigraphic record for implementing the GTS by defin-ing GSSPs of various CUs, improving magneto-biochronology and extending downwards the ATS. 相似文献
5.
6.
AntonioBrambati LauraCarbognin TullioQuaia PietroTeatini LuigiTosi 《《幕》》2003,26(3):264-268
The paper deals with the geological setting, history and subsidence of the Venetian Plain. Major attention is paid to the Pleistocene-Holocene stratigraphic sequence in the Lagoon of Venice, in relation to its origin that datesback to 6-7 kyr BP. Geological land subsidence, which played an important role in the origin and the evolution of the lagoon, and anthropogenic subsidence, that has recently assumed a major importance for the Venetian environment, are discussed. Considering also the sealevel rise, 23 cm loss in land elevation has occurred in the last century, leading to increased flooding events and environmental problems that require protective works. 相似文献
7.
1:5万区域地质调查工作中,在柴达木陆块北缘首次发现古元古代变质镁铁—超镁铁质岩,获得成岩年龄为1952±15Ma,其岩石化学、地球化学特征反映出岩浆来源于亏损地幔,反映出该地区克拉通在古元古代(19亿年)发生了一次强烈的裂解(洋)事件,对于研究柴达木盆地北缘元古代结晶基底地质构造演化及进一步探讨柴达木盆地的起源及构造演化过程提供了重要地质线索。 相似文献
8.
9.
10.
WEIHai-quan JINBo-lu LIUYong-shun 《东北亚地学研究》2004,7(1):28-35
A number of different lahars have been recognized from a systematic survey of a mapping project. The high setting temporamre feature of the deposits indicates a relationship between the lahar and the Millennium eruption event of Tianchi Volcano. The lahars caused a dramatic disaster. Recognize of the huge avalanche scars and deposits around Tianchi Volcano imply another highly destructive hazard. Three types of different texture of the avalanche deposits have been recognized. There was often magma mixing processes during the Millennium eruption of Tianchi Volcano, indicating a mixing and co-eruption regime of the eruption. 相似文献