全文获取类型
收费全文 | 60615篇 |
免费 | 1276篇 |
国内免费 | 1947篇 |
专业分类
测绘学 | 2324篇 |
大气科学 | 4738篇 |
地球物理 | 12010篇 |
地质学 | 24824篇 |
海洋学 | 4320篇 |
天文学 | 9694篇 |
综合类 | 2360篇 |
自然地理 | 3568篇 |
出版年
2022年 | 291篇 |
2021年 | 472篇 |
2020年 | 459篇 |
2019年 | 495篇 |
2018年 | 5528篇 |
2017年 | 4784篇 |
2016年 | 3545篇 |
2015年 | 951篇 |
2014年 | 1118篇 |
2013年 | 1889篇 |
2012年 | 2280篇 |
2011年 | 4384篇 |
2010年 | 3486篇 |
2009年 | 4205篇 |
2008年 | 3484篇 |
2007年 | 3996篇 |
2006年 | 1751篇 |
2005年 | 1407篇 |
2004年 | 1532篇 |
2003年 | 1429篇 |
2002年 | 1243篇 |
2001年 | 894篇 |
2000年 | 878篇 |
1999年 | 686篇 |
1998年 | 736篇 |
1997年 | 690篇 |
1996年 | 572篇 |
1995年 | 562篇 |
1994年 | 479篇 |
1993年 | 421篇 |
1992年 | 419篇 |
1991年 | 386篇 |
1990年 | 457篇 |
1989年 | 373篇 |
1988年 | 356篇 |
1987年 | 438篇 |
1986年 | 346篇 |
1985年 | 430篇 |
1984年 | 531篇 |
1983年 | 451篇 |
1982年 | 452篇 |
1981年 | 422篇 |
1980年 | 438篇 |
1979年 | 360篇 |
1978年 | 345篇 |
1977年 | 340篇 |
1976年 | 315篇 |
1975年 | 296篇 |
1974年 | 312篇 |
1973年 | 340篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
791.
792.
793.
794.
795.
796.
797.
798.
V.B. Vasilenko A.V. Tolstov V.A. Minin L.G. Kuznetsova N.V. Surkov 《Russian Geology and Geophysics》2008,49(12):894-907
The intensity of postmagmatic processes in the Botuobinskaya pipe kimberlites was estimated from the calculated content of normative secondary quartz (Q). Several simple algorithms are proposed to calculate the Q content from chemical analyses of kimberlites. Ten groups of altered kimberlites have been recognized from the Q contents. The contents of MgO, some trace elements, and LREE in the groups, the contents of Cr and Ca of crimson garnets, the diamond contents of kimberlites, and the average weight of diamonds decrease as the Q content increases. It is shown that the negative SiO2–MgO correlation is the most effective indicator of the postmagmatic alteration of kimberlites. As the degree of their secondary alteration increases, the kimberlites transform into an assemblage of quartz and clay minerals enriched in some trace elements and almost completely lacking REE and diamonds. 相似文献
799.
Experiment with poikilitic garnet at 3 GPa and 800 °C showed dehydration melting of its mineral inclusions, which is accompanied by the growth of (sub)euhedral garnet crystals inside the inclusion and/or xenomorphic garnets replacing the host mineral. The newly formed and host garnets differ drastically in composition. The inclusion surface is complicated by specific wedge-like protrusions or thin branches composed of melt or its crystallization products. The above features have been discovered in polymineral inclusions in garnet from low-temperature (650 °C) eclogite from the Yukon-Tanana terrane, Canada. The inclusions are interpreted as the crystallization products of in situ formed melt. 相似文献
800.
V.B. Bazarova L.M. Mokhova M.A. Klimin L.A. Orlova K.Yu. Bazarov 《Russian Geology and Geophysics》2008,49(12):978-985
Climatic changes in southeastern Transbaikalia in the Middle and Late Holocene and their influence on alluvial sedimentation environments are reconstructed from the results of study of the Ilya floodplain sediments (Alkhanai National Park). At the beginning of the Subboreal period, the regional climate became more arid, which led to a significant increase in steppe species communities in the landscapes. Intense climate aridization also took place at the beginning and at the end of the Subatlantic period of the Holocene. The alluvial-sedimentation rate increased during the weakening of aridization and decreased during cooling and the intensification of aridization. The obtained regional data are compared with data on the adjacent areas and the global climatic changes in the Northern Hemisphere. 相似文献