全文获取类型
收费全文 | 91篇 |
免费 | 18篇 |
国内免费 | 81篇 |
专业分类
大气科学 | 5篇 |
地球物理 | 5篇 |
地质学 | 169篇 |
海洋学 | 7篇 |
综合类 | 1篇 |
自然地理 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 8篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 4篇 |
2007年 | 11篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 13篇 |
2003年 | 7篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 4篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有190条查询结果,搜索用时 15 毫秒
51.
52.
某矿床为一大型的铜镍铂钯矿床,原矿石化学分析有用元素为:Pt1-38gtPd2-36gt、Cu0-14%、Ni0-22%。显微镜观察发现,矿石主要金属矿物为黄铜矿、紫硫镍矿、黄铁矿、磁铁矿、铬铁矿,脉石矿物为蛇纹石、辉石等。经显微镜观察以及电子探针扫描分析,铂钯矿物在矿石中嵌布颗粒粒度细小,与不同矿物连生,根据电子探针分析,仍有许多超显微状态的铂钯矿物赋存在硫化矿物中。1 样品制备与仪器设备及实验条件从原矿石中挑选部分有代表性矿石,切割抛光制成矿石光片,经显微镜镜下鉴定后,留待进行电子探针分… 相似文献
53.
中国铂矿资源严重不足,主要分布在中国西部,根据原生矿床特征可划分为4类:①硫化物型;②铬铁矿型;③辉石岩型;④层控型。寻找铂矿新类型和富铂(岩石)资源,应成为解决中国铂矿资源紧缺的重要任务。铂矿找矿方向:地台与地槽接合部位,特别是围绕着基性、超基性岩内外接触带,铂的预富集岩带与层控型铂矿带,另外还有砂铂型铂矿发育区有望扩大找铂前景。 相似文献
54.
Adsorption kinetics of the interaction between Pt, Pd and Rh(defined here as platinum group elements, PGEs)ions and macromolecular organic compounds(MOCs, 10 kDa), including humic acid, carrageenan and bovine serum albumin, and different cutoff fractions of natural organic matter(1 kDa and 3 kDa) obtained from seawater using centrifugal ultrafiltration devices were investigated. For a given element, all the adsorption kinetics did not reach equilibrium except the interaction between Pt and 1 kDa cutoff, and between Pd and humic acid.For all the tested MOCs, the adsorption kinetics could be divided into two stages, a rapid adsorption process in the first 8 h and the desorption stage after the first 8 h until the equilibrium. The change trend of partition coefficient(log_(10)K_d) values with experiment time was consistent with that of the kinetic curves. However, in the interaction between PGE ions and natural dissolved organic matter(NDOM), an obvious difference in the change trends of log_(10)K_d and kinetic curves was observed. It indicated that the partition behavior of PGE ions interacting with NDOM in seawater was a combined effect of different organic constituents. The adsorption and log_(10)K_d of PGEs in the 1 kDa NDOM fraction were higher and more stable than those in the 3 kDa NDOM fraction. The results also indicated that the 1–3 kDa NDOM may dominate the interaction between PGEs ions and NDOM. Moreover, no kinetic model could perfectly simulate the adsorption process. It indicated that the colloidal struction and morphology of MOCs or NDOM in seawater might be inhomogeneous. Hence, the interaction between PGE ions and organic matter in seawater was a complicated process and needs further research. 相似文献
55.
John B. Creech Bruce F. Schaefer Simon P. Turner 《Geostandards and Geoanalytical Research》2020,44(2):223-229
Recent developments in amplifier hardware enable low‐noise measurements of exceedingly small ion beams in isotope ratio analysis, yielding higher precision from smaller samples than ever before. To date, these amplifiers have largely been employed in thermal ionisation instruments, with few applications using plasma‐source (i.e., MC‐ICP‐MS) instruments. Here, we demonstrate the utility of these new generation 1013 Ω amplifiers in MC‐ICP‐MS, employing Pt isotopes as a case study, a system that could greatly benefit from the promised advances. The data demonstrate that for samples with low Pt abundance, for a modest increase in uncertainties, the amount of sample required can be reduced by a factor of 50–100. This technique thereby opens up new possibilities for analysis of samples that have low Pt mass fractions or were otherwise impossible to obtain in sufficient quantities. 相似文献
56.
57.
阴离子树脂-活性炭分离富集等离子体发射光谱法测定富钴锰结壳中的痕量金银铂钯 总被引:10,自引:1,他引:10
采用717阴离子树脂活性炭联合交换分离富集技术,电感耦合等离子体发射光谱法同时测定富钴锰结壳中痕量金、银、铂、钯。方法检出限四元素分别为:Au1. 3、Ag0. 4、Pd0. 6、Pt4. 8ng/g。样品加标回收率在89. 0% ~110. 3%,相对标准偏差3. 5% ~7. 8% (n=4)。方法已用于富钴锰结壳中痕量金银铂钯的测定。 相似文献
58.
Any mine planning requires careful prediction of both the head grade andtonnage ofmineralization. There are various methods of interpolation that attempt to provide reasonable estimatesat unsampled locations. All of these give realizations that are unduly smooth and extremevalues that occur in reality are not reflected in these estimates. Such methods, therefore,provide limited scope for accurate risk assessment. An alternative approach that is rapidlygaining popularity is the method of conditional simulation. This approach attempts to reproduceboth the grade distributions of the sample data as well as its spatial variability. In this paper,a case study is presented on a platinum mineralization to demonstrate and compare sequentialGaussian and sequential conditional simulation techniques and to quantify and discuss therelevant sensitivities. 相似文献
59.
根据 2 0世纪 90年代铂族金属矿床勘查的新发现 ,提出铂族金属矿床成因分类 ,探讨中国铂族金属找矿方向 ,提出“以绿找铂”、“以黄找铂”和“以黑找铂”的找矿原则 ,即在蛇绿混杂岩或基性—超基性岩分布区寻找基性—超基性岩浆岩型、岩浆热液型铂族金属矿以及与之有关的砂铂矿床 ,在金矿田中寻找伴生铂族金属矿床 ,在黑色页岩分布区寻找黑色页岩型铂族金属矿床。 相似文献
60.
文章对产于津巴布韦大岩墙内的哈特利(Hartley)铂矿床的地质特征和成因进行研究。津巴布韦大岩墙于新太古代侵入,在津巴布韦克拉通内形成南北段次级岩浆房格局。哈特利铂矿的铂族元素主要分布在杂岩体的中下部,与硫化物密切相关,主要含矿矿物为铋、碲矿物。在岩浆侵位的过程中发生结晶分异,形成了铂族元素和硫化物的垂向分带。哈特利矿床与中国金川等铂族元素矿床相比,其成岩成矿时代早,矿床特征、成矿元素组合方面均有明显不同。 相似文献