全文获取类型
收费全文 | 465篇 |
免费 | 19篇 |
国内免费 | 10篇 |
专业分类
测绘学 | 14篇 |
大气科学 | 53篇 |
地球物理 | 123篇 |
地质学 | 171篇 |
海洋学 | 44篇 |
天文学 | 65篇 |
综合类 | 1篇 |
自然地理 | 23篇 |
出版年
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 7篇 |
2020年 | 15篇 |
2019年 | 15篇 |
2018年 | 16篇 |
2017年 | 20篇 |
2016年 | 33篇 |
2015年 | 16篇 |
2014年 | 10篇 |
2013年 | 22篇 |
2012年 | 24篇 |
2011年 | 34篇 |
2010年 | 18篇 |
2009年 | 27篇 |
2008年 | 25篇 |
2007年 | 28篇 |
2006年 | 25篇 |
2005年 | 19篇 |
2004年 | 24篇 |
2003年 | 11篇 |
2002年 | 19篇 |
2001年 | 10篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1970年 | 1篇 |
1964年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有494条查询结果,搜索用时 15 毫秒
491.
Andrey Linhares Bezerra de Oliveira Júlio Carlos Afonso Lilian da Silva Arnaldo Alcover Neto Manuel Castro Carneiro Lílian Irene Dias da Silva Maria Inês Couto Monteiro 《Geostandards and Geoanalytical Research》2019,43(4):689-699
Rare earth elements (REEs) are very important to technological development as well as to geochemical and environmental studies. In this work, hydrofluoric acid (HF) was replaced by condensed phosphoric acid (CPA) in the digestion of geological samples, and the quantification of REEs was performed by inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Six international reference materials (RMs), named DC86318, CGL 111, CGL 124, CGL 126, OKA‐2 and COQ‐1 and three Brazilian ore samples, named Araxá, Catalão and Pitinga were analysed. Only zircon and xenotime, which are potential REE‐bearing minerals, were not completely dissolved. Nevertheless, no REE associated with zircon was detected. The investigated digestion method presented many advantages: It was relatively fast (3 h), avoided fluoride precipitation, it was less hazardous because handling diluted H3PO4 is safer than HF, NH4F or NH4HF2 aqueous solutions, it preserved the quartz fittings of the measurement equipment and the final solution contained lower levels of total dissolved solids than those produced by the fusion method. 相似文献
492.
Comparison of Fused Glass Beads and Pressed Powder Pellets for the Quantitative Measurement of Al,Fe, Si and Ti in Bauxite by Laser‐Induced Breakdown Spectroscopy
下载免费PDF全文
![点击此处可从《Geostandards and Geoanalytical Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Alexandrina A. C. Carvalho Victoria C. Alves Daniel M. Silvestre Flávio O. Leme Pedro V. Oliveira Cassiana S. Nomura 《Geostandards and Geoanalytical Research》2017,41(4):585-592
Due to matrix interference and sample particle size effects, some of the most important and difficult issues in laser‐induced breakdown spectroscopy (LIBS) analysis are the calibration and quantitative measurement of a complex matrix. This study proposes the use of borate fusion as an alternative sample preparation procedure for the quantitative measurement of Al, Fe, Si and Ti in bauxite by LIBS. Analytical calibration curves were made using bauxite certified reference materials (CRM), and the precision and accuracy of the methods were evaluated by analysing an additional bauxite CRM, using two different approaches: pressed powder pellets and fused glass beads. The borate fusion method was the most suitable sample preparation technique, since particle size effects and matrix interference could be minimised, obtaining better linearity on the analytical calibration curves (r2), and more accurate and more precise results for bauxite analysis. 相似文献
493.
Maria Aparecida Vendemiatto Jacinta Enzweiler 《Geostandards and Geoanalytical Research》2001,25(2-3):283-291
In this study, we used the modified Horwitz expression (Hc = 0.01c0.8495 , which gives the precision as a function of concentration) to evaluate and control the accuracy of results of silicate rock analysis obtained by X-ray fluorescence spectrometry. This expression is currently used by the organisers of the GeoPT international proficiency tests, to assign the precision limits of each analyte and subsequently to evaluate the data provided by laboratories whose main application is geochemistry. Results for major and trace elements, determined in glass disk and pressed pellets, respectively, were evaluated. Nine international silicate rock reference materials were analysed and results were compared to the recommended values plus and minus the limits given by the above expression. Those limits are easily attained for most major elements, but not for trace elements. Sample preparation and sub-sampling contributions to precision were evaluated by analysis of an in-house reference sample. In our results, precision does not follow the Horwitz expression relationship with concentration. It is known that the final accuracy in XRF analysis depends strongly on instrumental settings and on the uncertainties associated with the certified or recommended values of the reference materials used to calibrate the spectrometer, but our results indicate that the precision expression can be useful, especially to inspect and correct calibration curves and to check routine instrumental accuracy. 相似文献
494.
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