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 390 毫秒
151.
收集了6种产自肝癌高发区——江苏省启东市的红豆和6种产自国内其他地区的红豆,经过微波消解或干灰化法处理后,采用电感耦合等离子体发射光谱法(ICP-OES)、原子吸收光谱法(AAS)和原子荧光光谱法(AFS)测定了其中A l、B、Ba、Ca、Cd、Co、Cr、Cu、Fe、Hg、K、Mg、Mn、Mo、Na、N i、P、Pb、Rb、S、Se、Sr和Zn共23种矿质元素的含量,并用生物标准参考物质黄豆评价了分析方法的准确度。结果表明,红豆中人体必需宏量、微量元素含量极为丰富,而传统意义上的有害元素Pb、Cd、Hg含量均较低;与国内其他产地的红豆相比,江苏省启东市产红豆中B、Mg含量显著偏高(P0.05),而大多数矿质元素含量两相比较并不存在显著性差异。产自江苏省启东市的部分红豆样品和产自江苏省海门市的红豆样品中Cd含量极低,预示着自然生态环境中有效态Cd缺乏可能与肝癌的高发病率和高死亡率存在一定程度的相关性。  相似文献   
152.
采用原子吸收光谱仪(AAS),对脐橙的果皮、肉汁和囊瓣外衣中的10种微量元素进行了测定,同时也选择蜜桔进行了对比测定。结果表明,脐橙和蜜桔的果皮、肉汁和囊瓣外衣中含有比较丰富的人体必需的微量元素,且囊瓣外衣和果皮中的微量元素含量大多高于囊瓣中肉汁的微量元素的含量。这为脐橙和蜜桔药效功能的综合开发利用提供科学依据。  相似文献   
153.
Capelo JL  Fernandez C  Pedras B  Santos P  Gonzalez P  Vaz C 《Talanta》2006,68(5):1442-1447
The field of selenium speciation has been studied for decades and the growing interest in this field seems never to reach a plateau. Although powerful techniques based on mass spectrometry are nowadays used for selenium determination/speciation, few laboratories can support the high cost of such techniques. The hyphenation of chromatography to atomic absorption or atomic fluorescence spectrometry (AAS or AFS) is still a reliable and low-cost alternative for routine laboratories. In this work we present the most important parameters dealing with selenium speciation along with the latest trends in this subject, namely in the items related with sample treatment and hyphenation techniques with AAS and AFS detection.  相似文献   
154.
This is the first publication which describes the development of a reference material (RM) for the determination of 11 trace elements (Cu, Pb, Mn, Ni, Zn, Fe, Cd, Co, V, As and Al) in rainwater at microgram per liter concentrations. An interlaboratory comparison study for the determination of trace elements in rainwater was carried out for material performance studies to establish analyte concentrations with a stated uncertainty. Fifteen reputed laboratories from Asia, Europe and North America participated in the study. These laboratories used their regular in-house methods to analyze the rainwater samples. The aim of this study is to establish concentration levels of trace elements in rainwater based on interlaboratory study results. Details of the production, homogeneity and stability of the reference sample are given in this article. The organization of the study and the quality assurance measures undertaken at the organizer's laboratory are described. The analytical results obtained from individual laboratories and the analytical methods used for the determination of trace elements in rainwater are discussed. Based on the results obtained from the intercomparison study, certified values as well as informative values are assigned to the 11 trace elements in rainwater.  相似文献   
155.
The control of pesticides in surface, drinking and groundwater is nowadays a real necessity. In the European Community, their concentration must comply with the established parametric and environmental quality standards (EQSs). Regarding the new legislation, this article updates the information concerning the monitoring of pesticides and the technical specifications for their measurement in water samples where ultra-sensitive analytical methods are required. For some compounds, like pesticides, there is still a need to improve the performance of the existing methods. High sensitive techniques like gas chromatography tandem mass spectrometry (GC–MS/MS) and liquid chromatography coupled with mass spectrometry (LC–MS) have been developed. However, for most of the substances present at trace and ultra-trace levels the extraction and preconcentration steps are so far essential for their detection. Advances at a micro scale have been made and different types of microextractions are being developed. Liquid-phase microextraction (LPME) is an example. The study of this technique has increased in the last years and some innovations have been recently reported for pesticides water analysis. This article reviews the new developed LPME-based techniques and compares its performance with the analytical specifications established for pesticides water monitoring. The results show that LPME-based techniques can be a promising tool to improve the nowadays performance of methods used in pesticides water control.  相似文献   
156.
微波溶样FAAS法测定人发中锰   总被引:2,自引:0,他引:2  
明杰 《光谱实验室》2001,18(1):57-59
采用微波溶样技术消解头发样品,用FAAS法测定头发中锰,实验结果表明,用微波溶样技术消解头发具有节省时间,节约试剂,消解完全等优点,本方法的相对标准偏差为1.7%-3.6%,回收率为93.8%-102.5%.  相似文献   
157.
《Analytical letters》2012,45(7-8):1199-1206
Chemical analysis of sediments provides an efficient tool for water quality management. Ten sediment samples collected in 2008 from two locations situated in the Danube Delta Biosphere were analyzed in a comparative study of mobile metallic elements via two different pre-treatment techniques: air-drying followed by sieving and wet sieving. The experimental data proved that air-drying procedure produces drastic changes in mobility of the metallic elements from the sediments which were studied as an effect of the oxidizing conditions. Wet sediment or oxygen-free dried sediment is recommended to be used in environmental studies regarding determination of mobile fractions from sediment samples.  相似文献   
158.
捕集、释放原子吸收光谱法测定痕量Pb、Cd的研究   总被引:1,自引:0,他引:1  
利用双缝石英管原子捕集与释放装置,对GB/T 13662-92火 原子吸收光谱法中测量Pb和Cd的装置进行改进,在此基础上建立了一种简便,灵敏的测定痕量Pb和Cd的分析方法,其检出限分别为:Pb 3.13*10^-3 ug/ml,Cd2.23*10^-5ug/mL,应用于直接测定地表水,泉水中的痕量Pb和Cd。  相似文献   
159.
石墨炉原子吸收光谱法直接测定全血中砷   总被引:5,自引:0,他引:5  
研究了石墨炉原子吸收光谱法测定全血中砷的方法。用硝酸镍—重铬酸钾为基体改进剂,1:10稀释,建立了基体匹配校准加入法,方法检出限低,灵敏度高,测定结果满意。  相似文献   
160.
塞曼石墨炉AAS法直接测定硝酸银中的杂质   总被引:1,自引:0,他引:1  
本文介绍了利用塞曼石墨炉原子吸收法直接测定硝酸银中的杂质锰、镍、铜、铁和铬。方法简单、快速、检出限低、回收率好。  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