全文获取类型
收费全文 | 483篇 |
免费 | 46篇 |
国内免费 | 94篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 22篇 |
地球物理 | 166篇 |
地质学 | 201篇 |
海洋学 | 92篇 |
天文学 | 52篇 |
综合类 | 41篇 |
自然地理 | 32篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 20篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 23篇 |
2010年 | 20篇 |
2009年 | 29篇 |
2008年 | 30篇 |
2007年 | 25篇 |
2006年 | 37篇 |
2005年 | 36篇 |
2004年 | 36篇 |
2003年 | 45篇 |
2002年 | 29篇 |
2001年 | 21篇 |
2000年 | 18篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 18篇 |
1992年 | 23篇 |
1991年 | 16篇 |
1990年 | 5篇 |
1989年 | 14篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1985年 | 5篇 |
1983年 | 4篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1933年 | 2篇 |
1927年 | 3篇 |
1924年 | 2篇 |
排序方式: 共有623条查询结果,搜索用时 15 毫秒
621.
HUANG Zhilong XU Cheng Andrew McCAIG LIU Congqiang WU Jing XU Deru LI Wenbo GUAN Tao XIAO Huayun 《《地质学报》英文版》2007,81(4):622-636
Fluorite is one of the main gangue minerals in the Maoniuping REE deposit,Sichuan Province,China.Fluorite with different colors occurs not only within various orebodies,but also in wallrocks of the orefield.Based on REE geochemistry,fluorite in the orefield can be classified as the LREE-rich,LREE-flat and LREE-depleted types.The three types of fluorite formed at different stages from the same hydrothermal fluid source,with the LREE-rich fluorite forming at the relatively early stage,the LREE-flat fluorite in the middle,and the LREE-depleted fluorite at the latest stage.Various lines of evidence demonstrate that the variation of the REE contents of fluorite shows no relation to the color.The mineralization of the Maoniuping REE deposit is associated spatially and temporally with carbonatite-syenite magmatism and the ore-forming fluids are mainly derived from carbonatite and syenite melts. 相似文献
622.
Immunostimulants may improve disease resistance of aquaculture animals by promoting the nonspecific immunity response of the organisms. Five types of saccharides, including chitosan, yeast polysaccharide, burdock oligosaccharide, seaweed polysaccharide and lentinus edodes polysaccharide, were screened for potential use as immunostimulants by using spectrophotometry. The saccharides were injected into Apostichopus japonicus, a sea cucumber, and the lysozyme and superoxide dismutase (SOD) activities of the coelomic fluid and epidermal slime were monitored in six consecutive days. The results show that the lysozyme activity of the animal's coelomic fluid was significantly stimulated on day 2, day 4 and day 6 after the injection of the saccharides (P<0.05). The effects of chitosan and yeast polysaccharide were the most notable. The lysozyme activity of the epidermal slime was significantly increased by chitosana, yeast polysaccharide, seaweed polysaccharide, and burdock oligosaccharide on day 1 and day 2 after the injection (P<0.05). The SOD activity of the coelomic fluid was significantly promoted by the saccharides on day 2 and day 4 post-injection (P<0.05), while the SOD activity of the epidermal slime increased on day 2. These findings indicate that chitosan and yeast polysaccharide are the most effective immunostimulants and potential healthy anti-disease feedstuff for A. japonicus. 相似文献
623.
P. G. Brown P. J. A. McCausland A. R. Hildebrand L. T. J. Hanton L. M. Eckart H. Busemann D. Krietsch C. Maden K. Welten M. W. Caffee M. Laubenstein D. Vida F. Ciceri E. Silber C. D. K. Herd P. Hill H. Devillepoix Eleanor K. Sansom Martin Cupák Seamus Anderson R. L. Flemming A. J. Nelson M. Mazur D. E. Moser W. J. Cooke D. Hladiuk Barbara Malečić Maja Telišman Prtenjak R. Nowell The Golden Meteorite Consortium 《Meteoritics & planetary science》2023,58(12):1773-1807