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排序方式: 共有55条查询结果,搜索用时 19 毫秒
11.
B. V. Slobodin L. L. Surat R. F. Samigullina 《Russian Journal of Inorganic Chemistry》2009,54(5):797-802
Formation and stability temperatures were determined for the three polymorphs of copper pyrovanadate. The low-temperature β phase is formed at 500°C and is stable from room temperature to 610°C. The intermediate phase is stable within 610–705°C. The high-temperature γ phase is stable within 710–780°C. The rates of γ → α and α → β phase transitions upon cooling differ considerably. α-Cu2V2O7 detected at room temperature upon cooling of a molten sample is metastable. 相似文献
12.
Laphookhieo S Syers JK Kiattansakul R Chantrapromma K 《Chemical & pharmaceutical bulletin》2006,54(5):745-747
A new prenylated xanthone, 5-O-methylcelebixanthone (1), together with six known compounds; celebixanthone (2), 1,3,7-trihydroxy-2,4-di(3-methylbut-2-enyl)xanthone (3), cochinchinone A (4), alpha-mangostin (5), beta-mangostin (6) and cochinchinone C (7) were isolated from roots of Cratoxylum cochinchinense. Their structures were elucidated by spectroscopic methods. Compounds 2 and 4-7 showed cytotoxic activity against the human lung cancer cell line (NCI-H187) with IC(50) values ranging from 0.65 to 5.2 microg/ml. Compounds 1, 2, 6 and 7 also showed antimalarial activity against Plasmodium falciparum with IC(50) values of 3.2, 4.9, 7.2 and 2.6 microg/ml, respectively. 相似文献
13.
Danuta Frackowiak Surat Hotchandani G. Bialek-Bylka Roger M. Leblanc 《Photochemistry and photobiology》1985,42(5):567-572
Abstract— Photoacoustic spectra (PAS) of biliproteins, namely, R-phycoerythrin (PE) and C-phycocyanin (PC) and their mixture in anisotropic and isotropic polyvinylalcohol (PVA) films were measured under the illumination with polarized and natural light. Also samples in deuterated PVA were investigated. The yields of fluorescence of various chromophores of investigated biliproteins were obtained from PAS, absorption, fluorescence and fluorescence lifetime measurements. The deuteration of samples causes different changes in thermal deactivation of excitation of various chromophores. Ratios of PAS to absorption of the light polarized parallel and perpendicular to the direction of film stretching are different. The PAS amplitude of deuterated samples is higher than that for undeuterated. 相似文献
14.
Excited-state interactions between chlorophyll a (Chla) and gold nanoparticles have been studied. The emission intensity of Chla is quenched by gold nanoparticles. The dominant process for this quenching has been attributed to the process of photoinduced electron transfer from excited Chla to gold nanoparticles, although because of a small overlap between fluorescence of Chla and absorption of gold nanoparticles, the energy-transfer process cannot be ruled out. Photoinduced electron-transfer mechanism is supported by the electrochemical modulation of fluorescence of Chla. In absence of an applied bias, Chla cast on gold film, as a result of electron transfer, exhibits a very weak fluorescence. However, upon negatively charging the gold nanocore by external bias, an increase in fluorescence intensity is observed. The negatively charged gold nanoparticles create a barrier and suppress the electron-transfer process from excited Chla to gold nanoparticles, resulting in an increase in radiative process. Nanosecond laser flash experiments of Chla in the presence of gold nanoparticles and fullerene (C60) have demonstrated that Au nanoparticles, besides accepting electrons, can also mediate or shuttle electrons to another acceptor. Taking advantage of these properties of gold nanoparticles, a photoelectrochemical cell based on Chla and gold nanoparticles is constructed. A superior performance of this cell compared to that without the gold film is due to the beneficial role of gold nanoparticles in accepting and shuttling the photogenerated electrons in Chla to the collecting electrode, leading to an enhancement in charge separation efficiency. 相似文献
15.
Danuta Frackowiak Surat Hotchandani Roger M. Leblanc 《Photochemistry and photobiology》1985,42(5):559-565
Abstract— Photoacoustic spectra (PAS) of biliproteins: R-phycoerythrin (PE) with R-phycocyanin (PC) admixture in isotropic and anisotropic polyvinyl-alcohol (PVA) films were measured. The mixtures of biliproteins and chlorophyllin (Chllin) in PVA were also investigated. In order to establish the influence of PVA anisotropy on PAS amplitude, the stretched and unstretched PVA films colored by Congo red were studied. The films with PE and Chllin mixture when illuminated in the region of PE absorption, show higher PAS signals than the films with PE alone. This is explained by the excitation energy transfer from efficiently fluorescent PE to Chllin that has much lower yield of fluorescence. The stretched films always show a higher PAS signal than isotropic films because of the increase in the thermal conductivity of PVA. But normalized PAS of Congo red and Chllin in stretched PVA are similar to those in unstretched films.
Pigment molecules oriented parallel to the direction of film stretching have a lower rate of thermal deactivation compared to that of unoriented molecules as has been found by comparing PAS of differently oriented Congo red molecules using photoselection by polarized light. The same result was obtained for various PE chromophores which are differently oriented in anisotropic films. 相似文献
Pigment molecules oriented parallel to the direction of film stretching have a lower rate of thermal deactivation compared to that of unoriented molecules as has been found by comparing PAS of differently oriented Congo red molecules using photoselection by polarized light. The same result was obtained for various PE chromophores which are differently oriented in anisotropic films. 相似文献
16.
Sarot Cheenpracha Chatchanok Karalai Chanita Ponglimanont Kan Chantrapromma Surat Laphookhieo 《Helvetica chimica acta》2006,89(5):1062-1066
A new dimer 1 and two new cassane‐type diterpenes 2 and 3 , designated taepeenin J–L, were isolated from the seeds of Caesalpinia crista L. Compound 1 possesses a dimeric vouacapane skeleton. Their structures were elucidated on the basis of spectroscopic analysis. 相似文献
17.
18.
O. A. Lipina L. L. Surat M. A. Melkozerova A. P. Tyutyunnik I. I. Leonidov V. G. Zubkov 《Optics and Spectroscopy》2014,116(5):695-699
The crystal structure and luminescence properties of CaY2Ge3O10:Ln3+ (Ln = Eu, Tb) germanates synthesized via a conventional solid-state reaction and an ethylenediaminetetraacetic acid complexing process are studied. The CaY2 ? x Ln x Ge3O10 (Ln = Eu, Tb; x = 0–1.0, 2.0; Δx = 0.1) solid solutions have a monoclinic structure (space group P21/c, Z = 4), in which dopant ions occupy three nonequivalent noncentrosymmetric sites with different Ca2+/Ln3+ ratios. The effect of the synthesis methods, dopant concentrations, and excitation wavelengths on the luminescence properties of the compounds obtained is determined. 相似文献
19.
Wisanu ManeeratThunwadee Ritthiwigrom Sarot CheenprachaUma Prawat Surat Laphookhieo 《Tetrahedron letters》2011,52(26):3303-3305
Two new dimeric carbazole alkaloids, clausenawallines A and B, were isolated from the roots of Clausena wallichii. Their structures were elucidated by spectroscopic methods. Clausenawalline A was evaluated for its biological activities [anti-malaria (IC50 2.46 μg/mL), anti-TB (MIC 12.50 μg/mL)] and cytotoxicity against three human cancer cell lines [KB (IC50 7.87 μg/mL), MCF7 (IC50 25.43 μg/mL), and NCI-H187 (IC50 10.97 μg/mL)]. 相似文献
20.
Marina A. Melkozerova Nadezda V. Tarakina Lidia G. Maksimova Alexander P. Tyutyunnik Ludmila L. Surat Ivan I. Leonidov Vladimir G. Zubkov Elena V. Zabolotskaya Rina F. Samigullina 《Journal of Sol-Gel Science and Technology》2011,59(2):338-344
A modified Pechini method followed by conventional and microwave heating was used to synthesise the new promising Ln2MGe4O12 (Ln = Y, Eu; M = Ca, Zn, Mn) optical hosts. Comparison between solid-state and Pechini synthesis methods showed that the
latter reduces the temperature required for cyclo-tetragermanate formation. The highest yield of cyclo-tetragermanates for both methods is observed at 1,000–1,100 °C, with significantly shorter time of annealing in the case
of the Pechini synthesis. Compositional, structural and morphological characterisations of the samples obtained by both routes
were carried out using X-Ray powder diffraction, thermogravimetry, electron spin resonance spectroscopy, energy-dispersive
X-Ray spectroscopy and scanning electron microscopy. 相似文献