首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   616篇
  免费   2篇
  国内免费   4篇
化学   412篇
综合类   5篇
物理学   205篇
  2021年   2篇
  2019年   2篇
  2018年   3篇
  2017年   1篇
  2016年   7篇
  2015年   8篇
  2014年   3篇
  2013年   22篇
  2012年   49篇
  2011年   30篇
  2010年   24篇
  2009年   22篇
  2008年   21篇
  2007年   41篇
  2006年   36篇
  2005年   28篇
  2004年   31篇
  2003年   32篇
  2002年   28篇
  2001年   25篇
  2000年   18篇
  1999年   28篇
  1998年   13篇
  1997年   13篇
  1996年   24篇
  1995年   28篇
  1994年   18篇
  1993年   9篇
  1992年   12篇
  1991年   5篇
  1990年   5篇
  1989年   10篇
  1988年   7篇
  1987年   2篇
  1986年   6篇
  1985年   1篇
  1982年   2篇
  1981年   3篇
  1980年   1篇
  1976年   1篇
  1973年   1篇
排序方式: 共有622条查询结果,搜索用时 15 毫秒
81.
水样中铜,铅,镉的巯基棉富集火焰原子吸收测定   总被引:4,自引:0,他引:4  
在测定水样中铜、铅及镉的时候用巯基棉在采样现场富集简便快速,且灵敏准确,避免了样品运送的不便和萃取富集的繁琐。  相似文献   
82.
本实验对含13味中药的治肺癌复方原药,头煎及二煎残渣和浸汁,经0.45μ膜分离的颗粒物,可溶态,以及可溶态分别通过阳离子交换树脂,用三氯甲烷萃取后所得各自柱截留物,穿过物,有机相,水相等共15个样品中铬,镍,按照中药微量元素初级和次形态分析的要求,进行分析测定,以此计算出一套形态分析参数和相关数据,为探讨中草约中微量元素的化学形态提供了新的信息。  相似文献   
83.
微波消解-AAS测定柑橘中9种微量元素含量   总被引:1,自引:0,他引:1  
采用石墨炉和火焰原子吸收光谱法(AAS),测定了温州特产瓯柑和樟橘的果皮、肉汁和外衣中的9种微量元素。结果表明,果皮、果肉汁和外衣中含有丰富的人体必需的微量元素,且外衣和果皮中的微量元素含量高于肉汁中的微量元素含量。这为瓯柑和樟橘药效功能的综合开发利用提供科学依据。  相似文献   
84.
Abstract: This article presents a critical evaluation of the analytical procedures used for the determination of lead in seawater, which is important because lead is a good indicator of marine pollution caused by human activities. Sampling, storage, and pretreatment techniques are briefly overviewed, including the significance of systematic errors that cannot be corrected later on. The main techniques in this article are electrothermal–atomic absorption spectrometry (ET-AAS), inductively coupled plasma–mass spectrometry (ICP-MS), and voltammetry. Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma–optical emission spectrometry (ICP-OES) are treated as well, although their limits of quantification are not sufficient for a determination of lead in unpolluted seawater. Even when separation and preconcentration techniques are applied, these techniques are only capable of detecting lead in polluted coastal seawater. Separation and preconcentration are actually also required for ET-AAS and ICP-MS in order to determine the lowest concentrations of lead found in unpolluted open-ocean seawater, which is still a challenge for the analytical chemist.  相似文献   
85.
An analytical scheme for the determination of up to fifteen trace elements in nails and hair has been proposed. Samples were solubilized by means of aqueous tetraalkylammonium hydroxide (alkyl = methyl or ethyl). Cadmium, Cr, Cu, Fe, Mn, Pb and Zn were determined by pulse-nebulization flame AAS, employing the Slotted Tube Atom Trap (STAT) for Cd and Pb. Suitable chemical modifiers have been applied in electrothermal AAS (ETAAS) determinations of Cd and Pb (ammonium hydrogen phosphate), As, Sb, Se and Sn (palladium), while no modifier was needed in determinations of Al, Co, Cr, Mn, Mo and Ni. Calibration was performed by means of matrix-matched standards and the technique was verified by standard additions, comparison with neutron activation and analysis of hair reference material. The usefulness of this technique for occupational exposure monitoring is briefly discussed.  相似文献   
86.
Two analytical methods for the determination of cadmium in wheat flour by electrothermal atomic absorption spectrometry without prior sample digestion have been compared: direct solid sampling analysis (SS) and slurry sampling (SlS). Besides the conventional modifier mixture of palladium and magnesium nitrates (10 μg Pd + 3 μg Mg), 0.05% (v/v) Triton X-100 has been added to improve the penetration of the modifier solution into the solid sample, and 0.1% H2O2 in order to promote an in situ digestion for SS. For SlS, 30 μg Pd, 12 μg Mg and 0.05% (v/v) Triton X-100 have been used as the modifier mixture. Under these conditions, and using a pyrolysis temperature of 800 °C, essentially no background absorption was observed with an atomization temperature of 1600 °C. About 2 mg of sample have been typically used for SS, although as much as 3-5 mg could have been introduced. In the case of SlS multiple injections had to be used to achieve the sensitivity required for this determination. Calibration against aqueous standards was feasible for both methods. The characteristic mass obtained with SS was 0.6 pg, and that with SlS was 1.0 pg. The limits of detection were 0.4 and 0.7 ng g−1, the limits of quantification were 1.3 and 2.3 ng g−1 and the relative standard deviation (n = 5) was 6-16% and 9-23% for SS and SlS, respectively. The accuracy was confirmed by the analysis of certified reference materials. The two methods were applied for the determination of cadmium in six wheat flour samples acquired in supermarkets of different Brazilian cities. The cadmium content varied between 8.9 ± 0.5 and 13 ± 2 ng g−1 (n = 5). Direct SS gave results similar to those obtained with SlS using multi-injections; the values of both techniques showed no statistically significant difference at the 95% confidence level. Direct SS was finally adopted as the method of choice, due to its greater simplicity, the faster speed of analysis and the better figures of merit.  相似文献   
87.
巯基棉分离富集原子吸收光谱法测定铜精矿中金银   总被引:7,自引:0,他引:7  
本文详细地研究了在HCl介质中,巯基棉分离富集Au,Ag,KIO3-HCl解脱Au,原子吸收分光光度法测定金、银的方法。本方法一次溶样连续测定Au,Ag,简便快速,分析结果可靠,在Au32μg,Ag400μg范围内,Au回收率98.8%-101.2%,RSD为3%,Ag回收率97.3% ̄101.3%,RSD为2%。  相似文献   
88.
采用原子吸收分光光度法测定了11种治疗冠心病中成药物中镁含量。结果表明,药物中含有较丰富的镁元素,它为临床上探讨镁元素与冠心病关系提供了有用的数据。  相似文献   
89.
应用原子吸收光谱法检测了老年高血压、冠心病患者血清铁、红细胞内铁及血清铁蛋白、MCH、MCHC。发现老年冠心病患者血清铁、红细胞内铁、血清铁蛋白含量明显高于对照组(P<0.01)。老年高血压患者血清铁蛋白、红细胞内铁、MCH、MCHC也明显高于对照组(P<0.01),血清铁与对照组比较有显著性差异(P<0.05)。结果表明:老年高血压,冠心病患者存在铁代谢异常,其游离铁与储存铁的增加可能是其发病的危险因素之一。  相似文献   
90.
流动注射蒸气发生原子吸收光谱测定痕量铜   总被引:11,自引:1,他引:10  
建立了流动注射蒸气发生原子吸收光谱测定铜的新方法。使含有微量邻菲咯啉的样品溶液与硼氢化钠溶液汇合并反应生成蒸气态物质。在Ar载气下随反应液进入气液分离器分离 ,并进入石英管原子化器在 1 0 0 0℃下检测。在 5 0 0 μL进样体积下 ,铜的检出限为 1 8μg·L- 1 ,相对标准偏差为 2 6%(n =1 1 ,c=1 0 0 μg·L- 1 )。采样频率为 1 4 4样·h- 1 。分析标准参考物质大米粉和头发样品中的铜 ,结果与标准值一致  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号