全文获取类型
收费全文 | 355篇 |
免费 | 14篇 |
国内免费 | 39篇 |
专业分类
化学 | 324篇 |
晶体学 | 2篇 |
综合类 | 5篇 |
物理学 | 77篇 |
出版年
2023年 | 5篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 19篇 |
2012年 | 32篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 21篇 |
2005年 | 12篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 20篇 |
2001年 | 18篇 |
2000年 | 17篇 |
1999年 | 15篇 |
1998年 | 11篇 |
1997年 | 24篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 10篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有408条查询结果,搜索用时 15 毫秒
1.
催化荧光法测定痕量草酸 总被引:3,自引:0,他引:3
在硫酸介质中 ,草酸能催化重铬酸钾氧化罗丹明B褪色 ,使体系荧光猝灭 ,建立了催化荧光法测定草酸的新方法。催化反应在 50℃水浴中进行 1 0min ,为假零级反应。测定草酸的线性范围为 0 4~ 1 2 0mg·L- 1 ,其回归方程为ΔF =8 42c(mg·L- 1 ) 3 81 ,r=0 9983 ,检出限为 0 1 6mg·L- 1 。试验了 30种共存物质的干扰情况。此法用于生物样品中草酸含量的测定 ,结果满意。 相似文献
2.
本文拟定了一个催化荧光法测定痕量铜的新方法,确定了该催化反应的速度方程式和反应级数。方法检测限达0.1ng Cu/ml,相对标准偏差为3.7%,具有较好的选择性,可不经分离直接用于头发样品中铜的测定,回收及对照实验结果令人满意。 相似文献
3.
CTAB胶束微环境中BY增溶位置的探讨 总被引:7,自引:1,他引:7
本文用UV吸收光谱对(BY=CTAB)体系胶束化过程中预胶束的形成,以及预胶束向胶束的转变过程进行了分析。采用Gouy-Chapman模型,建立了CTAB胶束微环境中BY表现解离常数与胶束结构参数之间的定量关系,根据水溶液和各种盐浓度条件下CTAB胶束溶液中酸碱解离常数的测量,分析了BY在CTAB胶束扩散层中的增溶位置,讨论了CTAB胶束对BY选择性吸附的特性。 相似文献
4.
同步荧光法同时测定苯甲酸和水杨酸的研究 总被引:6,自引:0,他引:6
根据苯甲酸与水杨酸在酸性条件下荧光光谱出现的差异,用同步荧光法同时测定其混合物中二组份。苯甲酸及水杨酸的检测限分别为0.24μg/mL和0.25μg/mL相对标准偏差分别为1.3%和1.2%。方法用于商品杀菌腐剂中苯甲酸与水杨酸的同时测定,结果满意。 相似文献
5.
《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》1997,53(14):2553-2557
Photolysis of 2-nitrobenzyl methyl ether in Ar and N2 matrices at 12 K generated an intermediate with λmax at 430 nm, and which was itself photolabile at 430–460 nm. Matrix IR spectra, as well as the UV-visible absorption, were obtained for this species. An analogous intermediate had previously been observed in flash-photolysis studies of 2-nitrobenzyl 4-cyanophenyl ether, and had been assigned an o-quinonoid structure on the basis of its kinetic behaviour and the position of its UV-visible absorption. In the matrix studies with 2-nitrobenzyl methyl ether, the IR spectra confirmed the o-quinonoid structure. 相似文献
6.
A novel instrumental technique for the direct, fast, accurate, and precise determination of uranium in concentrates and other U-rich materials (as well as to mineralized rocks) is presented. The proposed technique is an absolute methodology, based on the comparison of the fluorescence of the accurately known standard with a sample of similar but unknown concentration in the low operational range of the instrument (on same sample-dilution basis), by the use of H3PO4-NH4H2PO4 as a fluorescence-enhancing reagent. The relative standard deviation of the proposed technique was 0.5-0.9% (n=9) at 18.1, 36.2, 61.2, and 99.6% U3O8. The proposed technique is suitable for the determination of uranium in samples arising from exploration projects, ores from mining operations, mill process samples, uranium ore concentrates leading to fuel fabrication as well as samples from environmental monitoring containing up to 100% uranium. The results are in good agreement with those obtained by titrimetric, gravimetric, and TBP extraction-H2O2 spectrophotometric methods. The precision of the technique is within the acceptable ‘pure geochemistry’ type of analysis (R.S.D. ∼ 1.0%) and is comparable even those obtained with titrimetric and gravimetric assay. The proposed differential technique coupled with flow injection may open up new advancement in instrumentation leading to design and development of microchemielectronic devices for direct on-line determination, more compatible with the tools of computer age as also to help in handling of radioactive solutions in chemical laboratories in uranium processing industries. 相似文献
7.
Mona Wells Michael Gösch Hauke Harms Jan Roelof van der Meer 《Mikrochimica acta》2005,151(3-4):209-216
This paper describes the development of an analytical technique for arsenic analyses that is based on genetically-modified
bioreporter bacteria bearing a gene encoding for the production of a green fluorescent protein (gfp). Upon exposure to arsenic
(in the aqueous form of arsenite), the bioreporter production of the fluorescent reporter molecule is monitored spectroscopically.
We compared the response measured as a function of time and concentration by steady-state fluorimetry (SSF) to that measured
by epi-fluorescent microscopy (EFM). SSF is a bulk technique; as such it inherently yields less information, whereas EFM monitors
the response of many individual cells simultaneously and data can be processed in terms of population averages or subpopulations.
For the bioreporter strain used here, as well as for the literature we cite, the two techniques exhibit similar performance
characteristics. The results presented here show that the EFM technique can compete with SSF and shows substantially more
promise for future improvement; it is a matter of research interest to develop optimized methods of EFM image analysis and
statistical data treatment. EFM is a conduit for understanding the dynamics of individual cell response vs. population response, which is not only a matter of research interest, but is also promising in the practical terms of developing
micro-scale analysis. 相似文献
8.
氧化藏红T褪色催化荧光法测定痕量钒 总被引:13,自引:3,他引:13
研究了在酸性介质中柠檬酸存在下,痕量钒(V)催化溴酸钾氧化藏红T的褪色反应及其动力学条件,建立了催化荧光测定痕量钒的新方法。催化反应在沸水浴中进行8min,为假零级反应,反应的表观活化能力为99.21kJ/mol,反应速度常数为0.12/s;该方法的检出限为2.2×10^-8g/L;线性范围为0.2 ̄2.4μg/L研究了共存离子的影响,用于人发和煤灰中痕量钒的测定,结果令人满意。 相似文献
9.
表面活性剂对铽—钛铁试剂体系纸上荧光的增敏作用及其应用 总被引:4,自引:0,他引:4
本文研究了9种表面活性剂对钛铁试剂体系纸上荧光法中Tb~(3+)特征荧光的增敏作用,并探讨了钛铁试剂-溴化十六烷基三甲胺体系纸上荧光法测定Tb~(3+)的最佳条件,Tb~(3+)的检测限为0.7ng。应用本方法成功地测定了中稀土分离富集物中Tb_4O_7的含量。 相似文献
10.
The fluorimetric determination of adrenaline is carried out in a continuous-flow assembly and by means of the molecular dissolved oxygen. The sample solution merges with an NaOH stream, then the resulting mixture is heated at 73 °C and led to the flow-cell of the fluorimeter. The flow-assembly is very simple and the procedure is quick (107 samples h–1) reproducible (R.S.D. 0.6%), selective and suitable to be applied to determination of adrenaline in formulations. Calibrations graph are linear over the ranges 0.05–15 and 20–40 mgl–1. 相似文献