全文获取类型
收费全文 | 23125篇 |
免费 | 5709篇 |
国内免费 | 8999篇 |
专业分类
测绘学 | 912篇 |
大气科学 | 1320篇 |
地球物理 | 3878篇 |
地质学 | 25517篇 |
海洋学 | 2914篇 |
天文学 | 134篇 |
综合类 | 1558篇 |
自然地理 | 1600篇 |
出版年
2024年 | 382篇 |
2023年 | 1216篇 |
2022年 | 1403篇 |
2021年 | 1455篇 |
2020年 | 1296篇 |
2019年 | 1425篇 |
2018年 | 1055篇 |
2017年 | 1153篇 |
2016年 | 1282篇 |
2015年 | 1305篇 |
2014年 | 1757篇 |
2013年 | 1430篇 |
2012年 | 1632篇 |
2011年 | 1684篇 |
2010年 | 1604篇 |
2009年 | 1585篇 |
2008年 | 1567篇 |
2007年 | 1567篇 |
2006年 | 1498篇 |
2005年 | 1322篇 |
2004年 | 1268篇 |
2003年 | 963篇 |
2002年 | 848篇 |
2001年 | 856篇 |
2000年 | 751篇 |
1999年 | 803篇 |
1998年 | 698篇 |
1997年 | 629篇 |
1996年 | 518篇 |
1995年 | 411篇 |
1994年 | 439篇 |
1993年 | 368篇 |
1992年 | 399篇 |
1991年 | 308篇 |
1990年 | 286篇 |
1989年 | 216篇 |
1988年 | 84篇 |
1987年 | 80篇 |
1986年 | 51篇 |
1985年 | 30篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 19篇 |
1981年 | 18篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1942年 | 10篇 |
1941年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
DavorPavelic IgorVlahovic JosipHalamic 《《幕》》2004,27(3):214-215
The 22nd IAS Meeting of Sedimentology was held in the Convention Centre of the Grand Hotel Adriatic, in a small touristic town Opatija, located on the eastern Adriatic coast where Central Europe and the Mediterranean meet. It was the second IAS Meeting held in Croatia--the first one, 4th IAS Regional Meeting of Sedimentology, was held in Split in 1983. The Meeting in Opatija was organized by the Institute of Geology (Zagreb) and the Croatian Geological Society. The sponsor was Ministry of Science and Technology of the Reoublic of Croatia. 相似文献
3.
里散半岛位于非洲板块和阿拉伯板块交接处的死海盆地中。该盆地面积大,构造简单且有下沉运动,说明它是一拉张型盆地。由重力异常数据发现死海盆地可划分成沿南北延伸各约30km长的几个块体,里散半岛是其中最深的一个。中生代沉积厚度约6km,更新世沉积厚度为9km。死海盆地的拉张距离为20km,表明死海盆地的年龄约3.3Ma。里散半岛下部的前寒武纪结晶基底磁化率较高,这与区内延续的构造活动性有关。 相似文献
4.
本文对1,2,5,8-四羟基蒽醌(THA)与镀形成配合物和THA进入β-环期精(β-CD)的内空腔与镀形成包结物这两种测定镀的荧光分析方法进行了比较,试验表明,后者的灵敏度和重现性有显着提高.选择性明显改善。详细研究了方法的测定条件.并应用于矿样中痕量镀的测定,结果符合质量要求。 相似文献
5.
6.
经过多年石油普查与勘探.广西发现多个含油气远景区.其中百色盆地、宁明盆地为较有利含油气区,南宁盆地、上思盆地为有利含油气区。 相似文献
7.
长乐-南澳左行韧性剪切带位于东南沿海,是酉太平洋大陆边缘构造带的一个组成部分。本文基于野外观察及室内分析,并借助透射电镜对变形石英的内部结构进行了观察,利用变形石英显微构造参数估算剪切带中的应力差值,由此探讨了形成构造岩的机制。 相似文献
8.
9.
GiovanniB.Piccardo 《《幕》》2003,26(3):193-199
Mantle peridotites were early exposed at the sea-floor of the Jurassic Tethys derived from the subcontinental mantle of the Europe-Adria system. During continental rifting and oceanic spreading, these lithospheric peri-dotites were percolated via diffuse reactive porous flowby melt fractions produced by near-fractional melting of the upwelling asthenosphere. Ascending melts inter-acted with the lower lithosphere, dissolving pyroxenes and precipitating olivine, and crystallized at shallower levels in the mantle column causing melt impregnation.Subsequent focused porous flow formed replacive dunitechannels, cutting the impregnated oeridotites, which were conduits for upward migration of MORB-type liq-uids. Melt migration produced depletionlrefertilization and significant heating of the percolatedlimpregnated mantle, i.e the thermochemical erosion of the litho-sphere. Impregnated and thermally modified lithos-pheric mantle was cooled by conductive heat loss dur-ing progressive lithosphere thinning and was intrudeaby MORB magmas, which formed Mg-rich and Fe-richgabbroic dykes and bodies. Alpine-Apennine ophiolitic peridotites record the deep-seated migration of melts which changed their compositions and dynamics during the rift evolution. The thermochemical erosion of the lithospheric mantle by the ascending asthenospheric melts, which induces significant compositional and rhe-ological changes in the lower lithosphere, is a major process in the evolution of the continent-ocean transi-tion towards a slow spreading oceanic system. 相似文献
10.
QinChengzhi ZhouChenghu PeiTao LiQuanlin 《中国地震研究》2004,18(2):178-187
The migration of strong earthquakes is an important research topic because the migration phenomena reflect partly the seismic mechanism and involve the prediction of tendency of seismic activity. Research on migration of strong earthquakes has mostly focused on finding the phenomena. Some attempts on getting regularity were comparatively subjective. This paper suggests that there should be indices of migration in earthquake dataset and the indexes should have statistical meaning if there is regularity in the migration of strong earthquakes. In this study, three derivative attributes of migration, i.e., migration orientation, migration distance and migration time interval, were statistically analyzed. Results in the North China region show that the migration of strong earthquakes has statistical meaning. There is a dominant migration orientation (W by S to E by N), a dominant distance ( ≤ 100kin and on the confines of 300 ~ 700km), and a dominant time interval ( ≤ la and on the confines of 3 - 4a). The results also show that the migration will differ slightly with different magnitude range or earthquake activity phase. 相似文献