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A selective and sensitive spectrophotometric method has been developed for determining the total amount of vanadium in carbonaceous shales (stone coal ores). The method is based on the reaction of vanadium(V) with the chromophore reagent 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in the presence of hydrogen peroxide. In a 0.072 mol l−1 sulfuric acid medium, 5-Br-PADAP reacts with vanadium(V) to form a red-violet complex with a maximum absorption peak at 596 nm with an apparent molar absorption coefficient of the complex of 8.45 × 104 l mol−1 cm−1 . Beer's law was obeyed in the range 0–25 μg vanadium in 25 ml of solution, with a correlation coefficient of 0.9995. Interferences due to various non-target ions were also investigated and high quantities of other common inorganic ions were tolerable. The method involved the dissolution of the ore sample by Na2 O2 fusion, followed by filtering of the alkali solution after which Fe(III), Cu(II), Ni(II) and Co(II) etc. were effectively separated from the solution by precipitation in a NaOH solution. Selectivity was increased with the use of EDTA as a masking agent. The vanadium in ore samples was determined with a relative deviation (RSD) between 0.20 and 0.76%, and has been successfully applied to the determination of vanadium-bearing stone coal ores. The results indicated that the accuracy of 5-Br-PADAP spectrophotometry is comparable with the ICP-AES method. The characteristics of the method, i.e., simplicity, selectivity, sensitivity and rapid calibration, make it specially suitable for routine analysis. 相似文献
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研究了碘化钾-甲基异丁基甲酮(KI—MIBK)萃取-火焰原子吸收分光光度法连续测定地球化学样品中痕量银、镉和铊的主要条件。通过对火焰原子吸收分光光度计气路控制系统及雾化器的改进,较大地改善了萃取-火焰原子吸收分光光度法测定银、镉和铊的稳定性和灵敏度。选择萃取酸度为1.2mol/L HCl、水相和有机相体积配比为3:1~4:1,方法精密度(RSD,n=12)为Ag4.5%~9.6%、Cd1.5%~7.9%、T14.5%~5.4%,检出限(3s)为Ag0.004μg/g、Cd0.007μg/g、T10.011μg/g,符合多目标地球化学调查样品测试及质量监控要求。用国家一级标准物质和密码组合标准物质进行验证,测试结果令人满意。 相似文献
225.
Coudé spectra taken in the red region of 49 bright B and Be stars were examined for the behaviour of Hα and the He I λλ 5876
and 6678 line profiles. 51 per cent of the stars were found to show Hα emission to some degree and 22 per cent showed helium
emission. Evidence is presented for the existence of drastic changes in the line profile and the radial velocity in some of
the stars on a time scale of fractions of a day.
Visiting Astronomer, Kitt Peak National Observatory and Cerro Tololo Inter-American Observatory, operated by the Association
of Universities for Research in Astronomy, under contract with the National Science Foundation. 相似文献
226.
为探讨海水水质监测的简便可行方法,对渤海、北黄海、胶州湾、东海、长江口、南海及珠江口几百个海水样品紫外扫描发现,不同海区海水紫外吸收约在200~220nm之间。其中渤海、北黄海与胶州湾海水样品在208~210nm之间,而东海、长江口、南海及珠江口水样在205nm附近。海水紫外吸收吸光度与高锰酸钾法测COD值之间具有良好的线性关系。所以提出了用紫外分光光度法测定海水COD值的方法,发现紫外分光光度法与碱性高锰酸钾法测定海水COD值无显著性差异,可以满足快速监测的需要。 相似文献
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Hakan Serbest 《洁净——土壤、空气、水》2023,51(2):2200229
In the present study, a method is proposed for the determination of lead at trace levels by slotted quartz tube-flame atomic absorption spectrophotometry (SQT-FAAS) after preconcentration with stearic acid coated magnetic nanoparticle-based dispersive solid phase extraction (SA-MNP-DSPE). The slotted quartz tube (SQT) is used to enhance the analyte atom residence time in the light path. Stearic acid coated magnetic iron oxide (Fe3O4) nanoparticles, which can be easily collected with an external magnet, are used as adsorbent in the extraction process. The limit of detection (LOD) and the limit of quantitation (LOQ) values of the proposed method are obtained as 0.90 and 2.9 µg L−1, respectively. The method allows high repeatability in a wide linear range between 5.0 and 250 µg L−1, and the relative standard deviation for six replicates is 5.8%. The detection power is enhanced by about 77-fold compared to the regular flame atomic absorption spectrophotometry (FAAS) system. The method is validated by recovery experiments to four different lake water samples. After the spiking tests, good recovery results are calculated between 97% and 106%. These results show that lead can be detected at low levels in lake water samples with high sensitivity, accuracy, and precision. 相似文献
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我国现行淡水水体中磷测定方法为钼酸铵分光光度法(GB 118931989),该方法检测下限为0.01 mg/L,但我国南亚热带地区部分水体的总磷以及多数水体的溶解态磷浓度均低于0.01 mg/L,通过对标准试样和野外水样的测定,分析该方法在监测低磷浓度水体中可能出现的问题并提出改进方法.结果表明:对于磷浓度低于0.01 mg/L的水体,国标法灵敏度低,准确性差.通过3个方面的改进可提高该方法测定的灵敏度和准确性:1)将消解水样体积由25 ml增加到50 ml,消解后不再进行二次稀释定容;2)改变显色剂的配制,显色剂由14%硫酸溶液50 ml、酒石酸锑钾溶液5 ml、4%钼酸铵溶液15 ml和0.1 mol/L的抗坏血酸溶液30 ml混合而成,现配现用;3)将测定波长设置为880 nm.改进后方法的灵敏度有较大提高,能准确、有效地检测磷浓度在0.003~0.01 mg/L的水样. 相似文献