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1.
M. M. Krayushkin M. A. Kalik D. L. Dzhavadov L. G. Vorontsova Z. A. Starikova A. Yu. Martynkin V. L. Ivanov B. M. Uzhinov 《Russian Chemical Bulletin》2000,49(10):1757-1762
A series of new photochromic compounds were obtained for the first time from 1,2-bis(2-ethylthio-3-thienyl)perfluorocyclopentene by substituting bromine atoms or carboxy, alkoxycarbonyl, and carbamoyl groups for hydrogen atoms in positions 4 and 4′. Introduction of these substituents causes a slight bathochromic shift (by 20–30 nm) of a long-wavelength absorption band for the cyclic form and significantly increases the quantum yields of photocyclization ФA→B and ring opening ФB→A. Depending on the nature of a substituent, ФA→B decreases in the order COOH>COOMe>CONHAr. The quantum yields are markedly reduced when the ethylthio groups in positions 5 and 5′ are replaced by ethylsulfonyl groups (a tenfold reduction in ФA→B and a four- to fivefold reduction in ФB→A) The most considerable bathochromic shift of a long-wavelength band and the highest quantum yields of forward and reverse photoreactions were observed for 1,2-bis(4-bromo-2-ethylthio-3-thienyl) perfluorocyclopentene. 1,2- Bis (2-ethyl-5-ethylthio-4-methoxycarbonyl-3-thienyl)perfluorocyclopentene was structurally characterized by X-ray diffraction analysis. 相似文献
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Krayushkin MM Yarovenko VN Semenov SL Zavarzin IV Ignatenko V Martynkin AY Uzhinov BM 《Organic letters》2002,4(22):3879-3881
[formula: see text] The influence of catalysts, acid chlorides, and solvents in the acylation of methyl 2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylate was studied. Conditions for the regioselective acylation processes were found. Thienopyrrole-based photochrome was synthesized for the first time. 相似文献
3.
The effects of the nature of solvent, temperature and complex formation with alkali and alkaline-earth metal cations, as well as protonation, on the efficiency and the kinetics of fluorescence of 3-azacrowned 7-diethylaminocoumarins have been studied. For the crown-ethers under investigation, the ratio of a dipole moment to the radius of Onsager cavity delta micro/rho is a constant value, and a macrocycle does not affect delta micro, and rho. The fluorescence of coumarin 1 in acetonitrile is quenched by an electron donor, triethylamine, with the Stern-Volmer constant being equal to (0.474+/-0.009) M(-1). The decrease in coumarin 1 fluorescence quantum yield upon the introduction of N-alkylazacrown moiety into position 3 is caused by an intramolecular photoinduced electron transfer from the nitrogen atom of macroheterocycle to the coumarin moiety, where the excitation is localized. The fluorescence quenching has an activation energy 2.32+/-0.05 kcal/mol in various hydrocarbons, and does not depend on the solvent viscosity. The fluorescence kinetics of free crowned coumarins in methanol is not monoexponential because of the existence of macrocycle conformers, or because of the hydrogen bond complex formation between the solvent and the nitrogen atom of macrocycle, in which the efficiency of intramolecular electron transfer is different. Upon complex formation with alkali and alkaline-earth metal cations and upon protonation, the fluorescence quantum yield increases and fluorescence decay becomes monoexponential. 相似文献
4.
Krayushkin M. M. Ivanov S. N. Martynkin A. Yu. Lichitsky B. V. Dudinov A. A. Uzhinov B. M. 《Russian Chemical Bulletin》2001,50(12):2424-2427
Procedures were developed for the synthesis of substituted bis(2,5-dimethyl-3-thienyl)furans based on 1,2-bis(2,5-dimethyl-3-thienyl)-2-hydroxyethanone. Dithienylethene structures in which the ethene fragment is involved in the furan or furopyrimidine system possess photochromic properties and their open forms exhibit fluorescence. 相似文献
5.
S. L. Dmitruk S. I. Druzhinin R. A. Minakova A. I. Bedrik B. M. Uzhinov 《Russian Chemical Bulletin》1997,46(12):2027-2031
The effects of alkylation of the 4-amino group, polarity and viscosity of a solvent, and temperature on the fluorescence ofN-(2,4-dimethylphenyl)imides of 4-amino-1,8-naphthalenedicarboxylic acid were studied. A decrease in the temperature and polarity
of 4-dimethylaminonaphthalimide to decrease and have almost no effect on the rate of emissive deactivation of excited state.
The abnormally low efficiency of fluorescence of 4-dimethylaminonaphthalimide in polar low-viscosity media at room temperature
is associated with the formation of a nonfluorescent charge-transfer state. The increase in the rate of radiationless deactivation
of 4-aminonaphthalimide in the alkylation of its amino group is associated with the increase in its electron-donor ability.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2142–2144, December, 1997. 相似文献
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Anomalously high fluorescence spectrum Stokes' shifts of 2(4-pyridyl)-5-(4-methylphenyl)oxazole, 2(4-pyridyl)-5-(4-methoxyphenyl)oxazole, 2(4-pyridyl)-5-(4-N,N-dimethylaminophenyl)oxazole have been found. The fluorescence spectra of the compounds studied are shifted to longer wavelengths as the solvent dielectric constant increases. The dipole moments of these compounds increase by 3–4 times upon excitation. The fluorescence spectra of the compounds investigated are shifted to shorter wavelengths, and the fluorescence quantum yields increase as the temperature decreases. The fluorescence rate constant of 2(4-pyridyl)-5-(4-N,N-dimethylaminophenyl)oxazole changes slightly as the temperature decreases from 293 K (relaxed state) to 114 K (mainly nonrelaxed state). It was concluded that the anomalously high fluorescence Stokes' shift of 2-pyridyl-5-aryloxazole derivatives is caused by solvent orientation relaxation. 相似文献