全文获取类型
收费全文 | 128篇 |
免费 | 28篇 |
国内免费 | 38篇 |
专业分类
化学 | 166篇 |
综合类 | 1篇 |
物理学 | 27篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 2篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有194条查询结果,搜索用时 15 毫秒
41.
《Mendeleev Communications》2020,30(4):442-444
- Download : Download high-res image (114KB)
- Download : Download full-size image
42.
本文研究了PEG2000铬菁R(NH4)2SO4体系对Co(Ⅱ)、Ni(Ⅱ)的非有机溶剂萃取行为。指出在pH=5的(NaAcHAc)水溶液中,有(NH4)2SO4存在下,Ni(Ⅱ)可被PEG相几乎完全萃取,而Co(Ⅱ)则基本上不被萃取。从而获得了Co(Ⅱ)与Ni(Ⅱ)混合离子的定量分离。 相似文献
43.
阴阳离子菁染料在溴碘化银乳剂颗粒上J-聚体反射光谱 总被引:1,自引:1,他引:0
本文对两种阴阳离子菁染料在碘溴化银立方体颗粒表面的聚集行为进行了研究。用紫外-可见分光光度计测定了菁染料J-聚集的反射光谱曲线。与对应的阴离子、阳离子菁染料各自在碘溴化银立方体颗粒表面的聚集进行了实验对比。结果表明:阴阳离子菁染料吸附在碘溴化银立方体颗料表面形成的J-聚集态的反射光谱具有单个阴离子、阳离子菁染料形成J-聚体反射光谱的峰值波长。表明阴阳离子菁染料具有两个感色区域,既有阴离子菁染料的感色区又有阳离子菁染料的感色区。 相似文献
44.
M. V. Kvach S. V. Gontarev I. A. Prokhorenko I. A. Stepanova V. V. Shmanai V. A. Korshun 《Russian Chemical Bulletin》2006,55(1):159-163
Synthesis of a phosphoramidite reagent for the preparation of oligonucleotides labeled at the 5′-end with a fluorescent dye,
3,3,3′,3′-tetramethyl-2,2′-indodicarbocyanine, is described. The efficiency of this reagent is confirmed by the synthesis
of several labeled oligonucleotides.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 154–158, January, 2006. 相似文献
45.
A general approach to the design of high-performance near-infrared (NIR) D-π-A type fluorescent dyes
A four-step method is presented as a general guideline for design of high performance NIR absorbing/emitting dyes. 相似文献
46.
将(未)确定的1-(3'-磺酸丙基)2,3,3-三甲基吲哚啉内盐与原乙酸三乙酯在吡啶或酸酐中回流合成了五个氮原子上带有磺酸丙基的取代吲哚碳菁染料. 这些染料和杂环氮原子上带有烷基取代的吲哚碳菁相比, 它们具有较高的熔点, 在极性溶剂中具有较高的溶解度. 这些染料的最大吸收值在540~580nm之间, 并具有较高的消光系数(1~2×10^5L·mol·cm^-^1) . 相似文献
47.
Piryatinskii Yu. P. Nazarenko V. G. Vasyuta R. M. Kachkovskii A. D. Maiboroda E. I. Zhukova O. A. Slominskii Yu. L. Tolmachev A. I. 《Theoretical and Experimental Chemistry》2003,39(4):230-234
Measurements were carried out for time-resolved fluorescence spectra of dye solutions containing thiacarbocyanine and its derivatives with ethylene and vinylene bridges in the polymethine chain. At low temperature, an additional band appears in the spectrum related to an intramolecular electronic transition. Analysis of the transition lifetimes and a quantum-chemical model indicated that this transition should be attributed to a short-lived asymmetrical component formed along with the symmetrical component upon relaxation of the excited state but not appearing at room temperature due to conformational transformations. 相似文献
48.
Some new experimental results are described on the acid catalysed reaction of the 4-Pyrazoline-3-on (1a) with aromatic aldehydes leading to the cationic derivatives4 and5.4-Pyrazoline-3-on-lithium (1b), synthesised for the first time, gives in good yield with 4-dimethylaminobenzaldehyde under mild condition the cyanine2b and with benzophenone the pyrazolyl-diphenylmethane dye8.
Zur Struktur von2a und4a siehe Lit.2. 相似文献
49.
Dr. Heinz Mustroph 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(23):e202103714
In the review on “Cyanine Dyes Containing Quinoline Moieties: History, Synthesis, Optical Properties and Applications” (K. Ilina, M. Henary, Chem Eur. J. 2021 , 27, 2430; https://doi.org/10.1002/chem.202003697 ), some essential aspects were incorrectly described and discussed. To avoid further confusion, this correspondence tries to clarify both the structures and the history of some cyanine and apocyanine dyes that were not presented sufficiently. 相似文献
50.
Janina Kabatc Magdalena Zasada Jerzy Pączkowski 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3626-3636
New three‐component photoinitiating systems consisting of a cyanine dye, borate salt, and a 1,3,5‐triazine derivative were investigated by measuring their photoinitiation activities and through fluorescence quenching experiments. Polymerization kinetic studies based on the microcalorimetric method revealed a significant increase in polymerization rate when the concentration of n‐butyltriphenylborate salt or the 1,3,5‐triazine derivative were increased. The photo‐induced electron transfer process between electron donor and electron acceptor was studied by means of fluorescence quenching and SrEt change of the fluorescence intensity. The experiments performed documented that an increase of the n‐butyltriphenylborate salt concentration dramatically increases the rate of dye fluorescence quenching, whereas the increasing of the 1,3,5‐triazine derivative concentration slows down the consumption of the dye. We conclude that the primary photochemical reaction involves an electron transfer from the n‐butyltriphenylborate anion to the excited singlet state of the dye, followed by the reaction of the 1,3,5‐triazine derivative with the resulting dye radical to regenerate the original dye. This reaction simultaneously produces a triazinyl radical anion derived from the 1,3,5‐triazine, which undergoes the carbon‐halogen bond cleavage yielding radicals active in initiation of a free radical polymerization chain. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3626–3636, 2007 相似文献