全文获取类型
收费全文 | 9745篇 |
免费 | 515篇 |
国内免费 | 43篇 |
专业分类
测绘学 | 423篇 |
大气科学 | 931篇 |
地球物理 | 2606篇 |
地质学 | 3707篇 |
海洋学 | 554篇 |
天文学 | 1569篇 |
综合类 | 52篇 |
自然地理 | 461篇 |
出版年
2023年 | 49篇 |
2022年 | 70篇 |
2021年 | 181篇 |
2020年 | 206篇 |
2019年 | 170篇 |
2018年 | 612篇 |
2017年 | 530篇 |
2016年 | 600篇 |
2015年 | 427篇 |
2014年 | 530篇 |
2013年 | 715篇 |
2012年 | 559篇 |
2011年 | 568篇 |
2010年 | 526篇 |
2009年 | 560篇 |
2008年 | 404篇 |
2007年 | 319篇 |
2006年 | 312篇 |
2005年 | 256篇 |
2004年 | 261篇 |
2003年 | 213篇 |
2002年 | 202篇 |
2001年 | 150篇 |
2000年 | 137篇 |
1999年 | 105篇 |
1998年 | 129篇 |
1997年 | 136篇 |
1996年 | 91篇 |
1995年 | 99篇 |
1994年 | 95篇 |
1993年 | 60篇 |
1992年 | 53篇 |
1991年 | 49篇 |
1990年 | 85篇 |
1989年 | 45篇 |
1988年 | 37篇 |
1987年 | 54篇 |
1986年 | 37篇 |
1985年 | 46篇 |
1984年 | 45篇 |
1983年 | 45篇 |
1982年 | 45篇 |
1981年 | 49篇 |
1980年 | 30篇 |
1979年 | 29篇 |
1978年 | 27篇 |
1977年 | 28篇 |
1975年 | 22篇 |
1973年 | 23篇 |
1972年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Jesper Rydén 《Geografiska Annaler: Series A, Physical Geography》2015,97(3):431-436
Statistical studies of extremes are of interest in the climatic sciences, in particular trends of periods of unusually warm or cold weather, which could be labelled warm and cold spells, respectively. We study the yearly number of spells in Uppsala, Sweden which from a data‐analytic point of view truly are counts, and employ theory and methods from the field of regression models for counts. A possible trend for the period 1840–2012 was investigated. The trend for warm spells is positive and demonstrated to be larger in magnitude compared with the one for cold spells, and is found to be statistically significant. The methodology could be extended to analyse other climate indicators. 相似文献
992.
993.
994.
995.
996.
997.
998.
Réka?LukácsEmail author Szabolcs?Harangi Olivier?Bachmann Marcel?Guillong Martin?Dani?ík Yannick?Buret Albrecht?von?Quadt István?Dunkl László?Fodor Jakub?Sliwinski Ildikó?Soós János?Szepesi 《Contributions to Mineralogy and Petrology》2015,170(5-6):52
A silicic ignimbrite flare-up episode occurred in the Pannonian Basin during the Miocene, coeval with the syn-extensional period in the region. It produced important correlation horizons in the regional stratigraphy; however, they lacked precise and accurate geochronology. Here, we used U–Pb (LA-ICP-MS and ID-TIMS) and (U–Th)/He dating of zircons to determine the eruption ages of the youngest stage of this volcanic activity and constrain the longevity of the magma storage in crustal reservoirs. Reliability of the U–Pb data is supported by (U–Th)/He zircon dating and magnetostratigraphic constraints. We distinguish four eruptive phases from 15.9 ± 0.3 to 14.1 ± 0.3 Ma, each of which possibly includes multiple eruptive events. Among these, at least two large volume eruptions (>10 km3) occurred at 14.8 ± 0.3 Ma (Demjén ignimbrite) and 14.1 ± 0.3 Ma (Harsány ignimbrite). The in situ U–Pb zircon dating shows wide age ranges (up to 700 kyr) in most of the crystal-poor pyroclastic units, containing few to no xenocrysts, which implies efficient recycling of antecrysts. We propose that long-lived silicic magma reservoirs, mostly kept as high-crystallinity mushes, have existed in the Pannonian Basin during the 16–14 Ma period. Small but significant differences in zircon, bulk rock and glass shard composition among units suggest the presence of spatially separated reservoirs, sometimes existing contemporaneously. Our results also better constrain the time frame of the main tectonic events that occurred in the Northern Pannonian Basin: We refined the upper temporal boundary (15 Ma) of the youngest counterclockwise block rotation and the beginning of a new deformation phase, which structurally characterized the onset of the youngest volcanic and sedimentary phase. 相似文献
999.
1000.