全文获取类型
收费全文 | 2454篇 |
免费 | 584篇 |
国内免费 | 784篇 |
专业分类
测绘学 | 150篇 |
大气科学 | 19篇 |
地球物理 | 199篇 |
地质学 | 3069篇 |
海洋学 | 54篇 |
天文学 | 6篇 |
综合类 | 214篇 |
自然地理 | 111篇 |
出版年
2024年 | 8篇 |
2023年 | 41篇 |
2022年 | 69篇 |
2021年 | 102篇 |
2020年 | 108篇 |
2019年 | 119篇 |
2018年 | 118篇 |
2017年 | 85篇 |
2016年 | 154篇 |
2015年 | 150篇 |
2014年 | 212篇 |
2013年 | 170篇 |
2012年 | 184篇 |
2011年 | 206篇 |
2010年 | 173篇 |
2009年 | 193篇 |
2008年 | 163篇 |
2007年 | 187篇 |
2006年 | 217篇 |
2005年 | 152篇 |
2004年 | 116篇 |
2003年 | 119篇 |
2002年 | 92篇 |
2001年 | 124篇 |
2000年 | 99篇 |
1999年 | 91篇 |
1998年 | 76篇 |
1997年 | 65篇 |
1996年 | 39篇 |
1995年 | 25篇 |
1994年 | 39篇 |
1993年 | 26篇 |
1992年 | 25篇 |
1991年 | 9篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有3822条查询结果,搜索用时 16 毫秒
81.
82.
水化学指标表示裘布依公式的应用 总被引:2,自引:0,他引:2
侯玉新 《水文地质工程地质》2003,30(4):97-101
从多矿物溶解化学动力学方程出发,推演并建立了由水化学指标表示的承压二维井流裘布依公式。结合水文地质、水文地球化学特征,列举了水文地质单元内不同区带、各种代表性矿物及相应组分化学指标的基本表达式。以山西省太原西峪煤矿所需解决的水文地质问题为例进行了定量研究与评价,其结果与已有的抽水试验资料接近,为矿井涌水量的评价开辟了一条新的道路。从事实上进一步论证了水化学指标表示裘布依公式的理论概括是正确的。 相似文献
83.
矿山工程裂隙破碎带的三维地震模式识别原理及应用效果 总被引:1,自引:0,他引:1
本文从时间域、频率域、三维空间域介绍了矿山工程裂隙破碎带主要的地震运动学、动力学属性参数,包括相对振幅、波峰相位时间、相似系数、主频带能量、三维空间时间梯度和相干系数等,提出了矿山工程裂隙破碎带三维地震属性的去噪平滑、归一化、相关分析、特征变换的处理方法以及裂隙破碎带的模式识别原理与方法,并用实例说明了该方法的应用效果。结果表明:模式识别法对于解释矿山工程的裂隙破碎带是有效的,并具有广阔的应用前景。 相似文献
84.
85.
Laser Ablation ICP-MS Analysis of Geological Materials Prepared as Lithium Borate Glasses 总被引:9,自引:0,他引:9
Stephen M. Eggins 《Geostandards and Geoanalytical Research》2003,27(2):147-162
A simple, rapid and precise method is described for determining trace elements by laser ablation (LA)-ICP-MS analysis in bulk geological materials that have been prepared as lithium borate glasses following standard procedures for XRF analysis. This approach reliably achieves complete sample digestion and provides for complementary XRF and LA-ICP-MS analysis of a full suite of major and trace elements from a single sample preparation. Highly precise analysis is enabled by rastering an ArF excimer laser (λ= 193nm) across fused samples to deliver a constant sample yield to the mass spectrometer without inter-element fractionation effects during each analysis. Capabilities of the method are demonstrated by determination of twenty five trace elements (Sc, Ti, V, Ga, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Hf, Ta, Pb, Th and U) in a diverse range of geological reference materials that includes peridotites, basalts, granites, metamorphic rocks and sediments. More than 90% of determinations are indistinguishable from published reference values at the 95% confidence level. Systematic bias greater than 5% is observed for only a handful of elements (Zr, Nb and U) and may be attributed in part to inaccurate calibration values used for the NIST SRM 612 glass in the case of Zr and Nb. Detection limits for several elements, most notably La, are compromised at ultra-trace levels by impurities in the lithium borate flux but can be corrected for by subtracting appropriate procedural blanks. Reliable Pb analysis has proved problematic due to variable degrees of contamination introduced during sample polishing prior to analysis and from Pt-crucibles previously used to fuse Pb-rich samples. Scope exists for extending the method to include internal standard element/isotope spiking, particularly where integrated XRF analysis is not available to characterise major and trace elements in the fused lithium borate glasses prior to LA-ICP-MS analysis. 相似文献
86.
William J. Chazey III Clive R. Neal Jinesh C. Jain William S. Kinman 《Geostandards and Geoanalytical Research》2003,27(2):181-192
The geochemical reference material BHVO-1 was analysed by a variety of techniques over a six year period. These techniques included inductively coupled plasma-mass spectrometry and atomic emission spectroscopy (ICP-MS and ICP-AES, respectively), laser ablation ICP-MS and spark source mass spectroscopy. Inconsistencies between the published consensus values reported by Gladney and Roelandts (1988, Geostandards Newsletter) and the results of our study are noted for Rb, Y, Zr, Pb and Th. The values reported here for Rb, Y, Zr and Pb are generally lower, while Th is higher than the consensus value. This is not an analytical artefact unique to the University of Notre Dame ICP-MS facility, as most of the BHVO-1 analyses reported over the last ten to twenty years are in agreement with our results. We propose new consensus values for each of these elements as follows: Rb = 9.3 ± 0.2 μg g-1 (compared to 11 ± 2 μg g-1), Y = 24.4 ± 1.3 μg g-1 (compared to 27.6 ± 1.7 μg g-1), Zr = 172 ± 10 μg g-1 (compared to 179 ± 21 μg g-1), Pb = 2.2 ± 0.2 μg g-1 (compared to 2.6 ± 0.9 μg g-1) and Th = 1.22 ± 0.02 μg g-1 (compared to 1.08 ± 0.15 μg g-1). 相似文献
87.
88.
89.
Javier Castro-Larragoitia Utz Kramar Harald Puchelt 《Journal of Geochemical Exploration》1997,58(1):81-91
The Ag---Pb---Zn---Cu---Au mining district of Santa María de La Paz has been extensively exploited for approximately 200 years. Consequences of these activities are several deposits of tailings with high As and heavy metal concentrations, which are completely unstable. The climate is semiarid and as the dumps have no protective cover, material from the dumps is dispersed by strong winds. It is also washed out during seasonally heavy rainfalls. By these processes approximately 100 km2 of surrounding have been contaminated by dump material. The As and heavy metal content of the soils was determined as well as their level in crops (Zea Maize) from agricultural lands in the vicinity of the dumps. In the direction of prevailing winds concentrations up to 1000 ppm Zn, 400 ppm Pb, 16 ppm Cd, 550 ppm Cu and 300 As have been detected in top soils. Using fuzzy cluster analysis the different contamination sources could be identified. Grains of corn from contaminated sites showed no critical concentrations, but leaves which are also used tor fodder, have As-concentrations up to 20 ppm. 相似文献
90.
滇黔桂微细浸染型金矿铅同位素组成及应用 总被引:6,自引:1,他引:6
滇黔桂微细浸染型金矿铅同位素组成及应用*刘显凡刘家军朱赖民(中国科学院地球化学研究所,贵阳550002)卢秋霞(成都理工学院,成都610059)关键词微细浸染型金矿铅同位素组成矿质来源上地幔分异混染滇黔桂1矿床地质背景研究区位于扬子地台西南缘与华南加... 相似文献