全文获取类型
收费全文 | 269篇 |
免费 | 41篇 |
国内免费 | 23篇 |
专业分类
化学 | 230篇 |
晶体学 | 9篇 |
力学 | 1篇 |
综合类 | 12篇 |
数学 | 2篇 |
物理学 | 79篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 14篇 |
2020年 | 11篇 |
2019年 | 5篇 |
2018年 | 15篇 |
2017年 | 21篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 11篇 |
2012年 | 19篇 |
2011年 | 24篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 13篇 |
2007年 | 14篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 11篇 |
2003年 | 5篇 |
2002年 | 13篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有333条查询结果,搜索用时 15 毫秒
91.
Determination of unsulphonated quinoline yellow in soft drinks by solid-phase spectrophotometry 总被引:1,自引:0,他引:1
Luis F. Capitán-Vallvey Ignacio de Orbe Sonia López-Rodríguez Ramiro Avidad 《Mikrochimica acta》1995,117(3-4):129-135
A spectrophotometric method for determination of quinoline yellow spirit soluble (QYSS) in the presence of sulphonated quinoline yellow water soluble (QYWS) in soft drinks at trace levels is reported. The method is based on the fixation of QYSS on C-18 silica gel, followed by measurement of its absorbance at = 418 nm in the solid phase after being packed in a 1-mm cell. The applicable concentration range was 1.5–15.0 ng/ml, the detection limit 0.4ng/ml and the relative standard deviation 5.2%. The method was applied satisfactorily to the determination of this compound in samples of commercial soft drinks. 相似文献
92.
93.
卟啉自由碱通常是紫或紫红色固体,遇酸则变成绿色,对光敏感。人工合成的卟啉最简单的是四苯基卟啉(H_2TPP)。美国专利曾将卟啉类化合物作为光氧化成象体系的增感剂。我们试图将H_2TPP作为VMD片(一种新型非银盐成象体系)的增感剂,未获成功。 相似文献
94.
R. White P. S. Thomas M. R. Philips R. Wuhrer J. P. Guerbois 《Journal of Thermal Analysis and Calorimetry》2007,88(1):181-184
The deleterious interaction
of some traditional sulphide artists pigments and copper ions results in the
formation of black copper sulphides, in particular, covellite (CuS), and,
hence, the discolouration of valuable artworks. In this paper the interaction
of malachite, a source of copper(II) ions, with the pigment cadmium yellow,
a sulphide pigment comprising of a solid solution of cadmium and zinc sulphides,
is investigated by XRD and TG-MS. XRD showed the presence of the copper sulphide
and cadmium carbonate phases, produced by a simple ion exchange mechanism.
TG-MS showed the complexity of the range of metastable phases produced. The
identification of these phases, however, requires further work. 相似文献
95.
本文研究了以十二烷基三庚基碘化铵-柠檬黄缔合物为活性材料的PVC膜电极和涂丝电极,两电极对柠檬黄浓度在1.0×10~(-6)~1.0×10~(-3)mol/L间的响应符合Nernst关系式,斜率为20.0±1.0mV/PC(22℃),pH范围为4.0~9.4,电极的选择性、重现性和稳定性良好。对样品的测定结果与分光光度法测定结果基本一致。该方法简便、准确、可靠。 相似文献
96.
Khalid M. Tawarah 《Journal of inclusion phenomena and macrocyclic chemistry》1992,14(3-4):195-204
The effect of temperature on the UV-visible spectra of the acid forms of methyl orange and methyl yellow in the presence of - and-cyclodextrins was analysed in terms of 1 : 1 inclusion processes. Three inclusion processes were considered for each azo dye/cyclodextrin system. The processes are the apparent inclusion process, the ammonium inclusion process, and the azonium inclusion process. The values of H
0 and S
0 are reported for each process. The inclusion complexes of the ammonium tautomer are more stable than those of the azonium tautomer and -cyclodextrin inclusion complexes are more stable than those of-cyclodextrin. The inclusion processes resulted in a shift in the position of the tautomeric equilibrium of an azo dye. A significant color fading was observed in -cyclodextrin/methyl yellow solutions. No measurable changes in the absorbances were observed in the case of azo dye solutions containing -cyclodextrin. 相似文献
97.
铅铬黄粒子的微胶囊化及其表面形貌的表征 总被引:2,自引:0,他引:2
研究了铅铬黄粒子的微胶囊化及其机理;探讨了对粒子表面形貌的量化表征方法.结果表明,在油包水(W/O)乳液中对铅铬黄粒子进行无机微胶囊化是一提高其耐酸、碱性的有效方法.颜料粒子的表面形貌可用其表面分形维数(D)量化表征. 相似文献
98.
99.
Tetracycline antibiotics (TCs) such as doxycycline (DOTC), chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline
(TC) react with Cu(II) in pH 3.5 BR buffer medium to form 1:1 cationic chelates, which further react with titan yellow to
form 2:1 ion association complexes. These result in great enhancement of resonance Rayleigh scattering (RRS) and the appearance
of new RRS spectra. The ion association complexes of DOTC, CTC, OTC, and TC have similar spectral characteristics and their
maximum RRS wavelengths are all located at 464 nm. The quantitative determination ranges and the detection limits (3σ) of the four TCs are 0.037–4.8 μg mL−1 and 11.2 ng mL−1 for DOTC, 0.041–5.2 μg mL−1 and 12.4 ng mL−1 for CTC, 0.050–4.8 μg mL−1 and 15.1 ng mL−1 for TC, and 0.088–5.0 μg mL−1 and 26.3 ng mL−1 for OTC, respectively. The optimum reaction conditions, the effects of foreign substances, the structure of ternary complexes,
and the reaction mechanism are discussed. A sensitive, rapid, and simple RRS method for the determination of DOTC has been
developed. 相似文献
100.
Azo dyes, which are common in the environment, can be toxic to various organisms. In order to determine the molecular mechanism of acid yellow 11(AY) toxicity, we studied the effect of AY exposure to the common protein bovine serum albumin (BSA) by several spectroscopic techniques including fluorescence spectroscopy, ultraviolet spectrophotometry (UV) and circular dichroism (CD). It could be concluded from the fluorescence spectra that the quenching effect of BSA by AY was mainly due to complex formation which was unrelated to the absorption of AY. The enthalpy change (ΔH) and entropy change (ΔS) were found to be −21.94 kJ/mol and 30.04 Jmol-1 K-1, respectively. The results confirm that electrostatic attraction was the predominant intermolecular force between BSA and AY. Furthermore, the binding distance (r) between AY and the inner tryptophan residue of BSA was determined to be 3.541 nm on the basis of Forster theory of non-radiative energy transfer. In addition, the conformational changes of BSA in the presence of AY were also analyzed by UV and CD. These results indicated that AY could interact with BSA by complex formation, which also affected the structure of BSA. 相似文献