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991.
992.
Introduction In the years when the reliable data could not be obtained and in the analysis of strain property and magnitude in history, the intensity, property and activity pattern of strain field were mainly inferred on the bases of geometric characters of surface traces and behaviors (especially the faults) as well as the characteristics of petrology (XIE, et al, 1993; Molnar, Tapponnier, 1975, 1977; Tapponnier, Molnar, 1977; FU, et al, 2000). However, they are the averaged results accumu… 相似文献
993.
1690年以来全球非偶极子磁场的变化特征 总被引:1,自引:1,他引:1
根据J Bloxham和A Jackson地磁场模型,计算和分析了1690-1990年期间非偶极子磁异常的变化特片。结构表明,1690年以来一直存在的变化磁异常有7个,在一定时期内出现的磁异常有3个,它们是1830年以后出现的北太平洋负磁异常、1850年以后出现的东南太平洋负磁异常和1690-1900年期间在南太平洋地区出现的负磁异常。各个磁异常的强度和中心位置随时间变化,变化趋势各不相同。与根据IGRF模型计算的20世纪的磁异常变化比较,除非洲负磁异常外,两种模型得出的其它磁异常在同一时段内的变化趋势基本一致。 相似文献
994.
The height datum/geodetic datum problem 总被引:2,自引:0,他引:2
995.
ET0模型在不同地区具有不同的适用性,而对极端干旱的塔克拉玛干沙漠南缘绿洲的ET0模型的适用性研究较为稀缺。利用2006—2014年生长季(4—10月)策勒气象站逐日气象资料,以自动称重式蒸渗仪实测数据为标准,采用最大绝对误差(MAE)、均方根误差(RMSE)、模型效率(EF)和一致性指数(d)4个指标,在日、月时间尺度上评价了6种常用ET0模型在策勒绿洲的适用性,并使用回归修正法和比例修正法分别修正了这6种模型。结果表明:(1)日、月时间尺度上,Hargreaves-Samani(H-S)模型高估程度较大,其余模型均不同程度低估,拟合度由高到低依次为FAO-56PM、Jensen-Haise(J-H)、Priestley-Taylor(P-T)、Makkink、Turc、H-S。(2)所有ET0模型月值变化趋势与蒸渗仪实测值基本一致,除FAO-56PM和Turc模型计算的ET0月值在6月达到峰值外,其余模型均在7月达到峰值,在生长季尺度所有模型ET0月值与蒸渗仪实测值呈显著相关。(3)日、月时间尺度上,回归修正法和比例修正法修正后的ET0模型计算结果与蒸渗仪实测值均呈极显著相关,回归修正法优于比例修正法。(4)相关性分析表明,对策勒绿洲ET0影响由高到低的气象因子依次为 > >P> > > > 。 相似文献
996.
Michael A.W. Marks Roberta L. Rudnick Thomas Ludwig Horst Marschall Thomas Zack Ralf Halama William F. McDonough Detlef Rost Thomas Wenzel Edward P. Vicenzi Ivan P. Savov Rainer Altherr Gregor Markl 《Geostandards and Geoanalytical Research》2008,32(3):295-310
Two large pegmatitic crystals of sodic pyroxene (aegirine) and sodic amphibole (arfvedsonite) from the agpaitic igneous Ilímaussaq Complex, south Greenland were found to be suitable as reference materials for in situ Li isotope determinations. Lithium concentrations determined by SIMS and micro‐drilled material analysed by MC‐ICP‐MS generally agreed within analytical uncertainty. The arfvedsonite crystal was homogeneous with [Li] = 639 ± 51 μg g?1 (2s, n = 69, MC‐ICP‐MS and SIMS results). The aegirine crystal shows strongly developed sector zoning, which is a common feature of aegirines. Using qualitative element mapping techniques (EPMA), the homogeneous core of the crystal was easily distinguished from the outermost sectors of the crystals. The core had a mean [Li] of 47.6 ± 3.6 μg g?1 (2s, n = 33) as determined by SIMS. The seven micro‐drilled regions measured by solution MC‐ICP‐MS returned slightly lower concentrations (41–46 μg g?1), but still overlap with the SIMS data within uncertainty. Based on MC‐ICP‐MS and SIMS analyses, the variation in δ7Li was about 1‰ in each of the two crystals, which is smaller than that in widely used glass reference materials, making these two samples suitable to serve as reference materials. There was, however, a significant offset between the results of MC‐ICP‐MS and SIMS. The latter deviated from the MC‐ICP‐MS results by ?6.0 ± 1.9‰ (2s) for the amphibole and by ?3.9 ± 1.9‰ (2s) for the aegirine. This indicates the presence of a significant matrix effect in SIMS determinations of Li isotopes for amphibole and pyroxene relative to the basalt glasses used for calibration. Based on the MC‐ICP‐MS results, mean δ7Li values of +0.7 ± 1.2‰ (2s, n = 10) for the arfvedsonite crystal and of ?3.7 ± 1.2‰ (2s, n = 7) for the core of the aegirine crystal were calculated. Adopting these values, SIMS users can correct for the specific IMF (instrumental mass fractionation) of the ion probe used. We propose that these two crystals serve as reference materials for in situ Li isotope determinations by SIMS and pieces of these two crystals are available from the first author upon request. 相似文献
997.
998.
Michael Wiedenbeck 《Geostandards and Geoanalytical Research》2008,32(4):489-494
Secondary ion mass spectrometry (SIMS or ion microprobe) remains one of the most powerful tools available to the analytical geochemist. Despite the impressive progress witnessed by other competing laboratory methods over recent years, SIMS remains unsurpassed in its combination of small sampling volumes with low analytical uncertainties. Although the current SIMS analytical design has existed for over three decades, the period 2006–2007 saw significant advances in instrumentation, analytical methodology and, not least, the characterisation of new reference materials upon which all analyses depend. As of the end of 2007 the SIMS geoscience literature was reporting total sampling masses down to the 10 fg range, spatial resolution of better than 100 nm and uncertainties on major element isotope ratio determinations of better than ± 0.2‰ (1s). This article intends to synthesise the progress made by the geo‐SIMS community during this two year period and will also highlight some specific research results that were only possible due to the unique capabilities provided by SIMS. 相似文献
999.
Total Sulfur Concentration in Geological Reference Materials by Elemental Infrared Analyser 总被引:1,自引:0,他引:1
L. Paul Bédard Dany Savard Sarah-Jane Barnes 《Geostandards and Geoanalytical Research》2008,32(2):203-208
Total sulfur is an analyte for which there are few determinations published, despite the fact that it is a very important element (e.g., a major element in most ores, an important gas constituent in global warming, an active participant in acid drainage). Most geological reference materials have very poor quality sulfur results, that is with relative standard deviations (RSD) in the range of 30–50%, even for concentrations over 100 μg g−1 S, which compromises their use as calibrators. In order to provide modern results with low RSD, sulfur was determined in twenty-nine geological reference materials with a state-of-the-art elemental S/C analyser using metal chips (certified reference materials with a traceability link) and analytical grade sulfur for high concentration samples. Analytical parameters (sample mass, crucible degassing, calibration strategy, etc.) were optimised by testing. Our results agreed with reference material values provided by issuing bodies. Results for CCRMP SY-2 (129 ± 13 μg g−1 S), which has been proposed as a sulfur reference material, were in agreement with the proposed modern value of 122 ± 3.7 μg g−1 S. 相似文献
1000.