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891.
Yu. A. Rozin V. F. Gryazev V. E. Blokhin Z. V. Pushkareva G. É. Martina 《Chemistry of Heterocyclic Compounds》1974,10(11):1350-1353
The rate constants and activation energies for homolytic dissociation of 2,2-di[ ()-naphthyl]-, 2,2-diquinolinyl-, and 2,2-di(9-acridinyl)-4,4,5,5-tetraphenyldiimidazolyls in toluene in the presence of,-diphenyl--picrylhydrazine were determined. The degrees of dissociation of the diimidazolyls were found. The effect of substituents on the stability of imidazolyl radicals is discussed.See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1536–1539, November, 1974. 相似文献
892.
Z. A. Ibraeva N. V. Nekrasov B. S. Gudkov V. I. Yakerson Z. T. Beisembaeva E. Z. Golosman S. L. Kiperman 《Theoretical and Experimental Chemistry》1991,26(5):584-588
The kinetics of hydrogenation of CO2 to methane on an NKM-4A nickel-containing catalyst was studied in a wide range of change of partial pressures of hydrogen and carbon dioxide at 498–543 K. It was shown that when hydrogen is replaced by deuterium in the reaction, a reverse kinetic isotope effect is observed. The kinetic equation of the reaction was derived and a stepwise scheme is proposed which includes the involvement of oxygen-containing intermediates in the process without preliminary dissociation of CO2.Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 26, No. 5, pp. 620–624, September–October, 1990. 相似文献
893.
T. Meisel K. Seybold Z. Halmos J. Róth Cs. Mélykuti 《Journal of Thermal Analysis and Calorimetry》1976,10(3):419-431
We have studied the thermal behaviours of the fatty acid (C1-C9, C12, C14, C16 and C18) thallium(I) salts.Investigating the dependence of the thermal decomposition reactions on the experimental conditions, we established that they decompose differently depending on the atmosphere, and on the shape and material of the sample holders.We also determined the heat-stable temperature ranges of the compounds in which they can be investigated without any thermal decomposition.The temperatures and enthalpy changes of the polymorphic and phase changes were measured and the corresponding entropy changes were calculated.
Zusammenfassung Das thermische Verhalten der Thallium(I)-Salze der Fettsäuren mit C1 bis C9, C12, C14 und C18 wurden untersucht. Die Temperaturen und Enthalpien der einzelnen polymorphen und Phasenänderungen, sowie die thermische Stabilität der Verbindungen wurden bestimmt. Es wurde festgestellt, daß die zu Ketonen und Gemischt-Ketonen führende thermische Zersetzung in der Schmelzphase von Destillationsprozessen begleitet wird, welche von der Molekülstruktur und von zahlreichen Versuchsbedingungen abhängig sind.
Résumé Etude du comportement thermique des sels de thallium(I) d'acides gras (de C1 à C9, C12, C14 et C18). L'étude de la décomposition thermique en fonction des conditions expérimentales a permis d'établir que les sels étudiés se décomposent différemment suivant l'atmosphère utilisée, ainsi que suivant la forme et la nature des supports échantillons. Détermination des domaines de température où ces composés restent thermiquement stables. Mesure des températures et des variations d'enthalpie des transitions de phase et des transitions polymorphiques et calcul des variations d'entropie correspondantes.
(I) C1-C9, C12, C14, C16, C18. , . , , , .相似文献
894.
Conclusions During the reaction of hydrazines and o-phenylenediamine with 2-halosubstituted (3-keto-esters, including fluoroalkyl substituted, two reaction paths are realized; substitution of the halogen atoms in position 2 by hydrogen and condensation with formation of various compounds depending on the structure of the starting -ketoester and dinucleophile.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2527–2535, November, 1987. 相似文献
895.
A. M. Moiseenkov V. V. Veselovskii Z. G. Makarova V. M. Zhulin 《Russian Chemical Bulletin》1987,36(5):1057-1059
Conclusion The reaction of PhSOCl with myrcene at high pressure leads to the cis-1,4 addition product.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5 pp. 1143–1145, May, 1987. 相似文献
896.
Magnetic beads as interfacial nanoprobes 总被引:1,自引:0,他引:1
Helseth LE Wen HZ Heinig P Fischer TM 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6556-6559
We use paramagnetic beads to probe strongly localized magnetic fields from one-dimensional nanomagnets. Using a polarization microscope in reflection mode, we find that light reflected from beads exhibits intensity fluctuations which may help us understand Brownian motion near interfaces. We estimate the height fluctuations and femtonewton forces acting on the beads. 相似文献
897.
Both (E)- and (Z)-isomers of (S)-14-methyl-8-hexadecenal (trogodermal) were synthesized from 100% optically pure (R)-(+)-citronellic acid. These antipodes of the khapra beetle pheromone were 1/500 to 1/1000 times as active as the natural (R)-pheromone. Determination of the optical purities of citronellic acid and related compounds was achieved by hplc method. Warning was made not to forget the measurement of density in expressing the optical rotation of a neat liquid as [α]D (neat). 相似文献
898.
Jun Liu Kelton A. Schleyer Tyrel L. Bryan Changjian Xie Gustavo Seabra Yongmei Xu Arjun Kafle Chao Cui Ying Wang Kunlun Yin Benjamin Fetrow Paul K. P. Henderson Peter Z. Fatland Jian Liu Chenglong Li Hua Guo Lina Cui 《Chemical science》2021,12(1):239
Heparanase (HPA) is a critical enzyme involved in the remodeling of the extracellular matrix (ECM), and its elevated expression has been linked with diseases such as various types of cancer and inflammation. The detection of heparanase enzymatic activity holds tremendous value in the study of the cellular microenvironment, and search of molecular therapeutics targeting heparanase, however, no structurally defined probes are available for the detection of heparanase activity. Here we present the development of the first ultrasensitive fluorogenic small-molecule probe for heparanase enzymatic activity via tuning the electronic effect of the substrate. The probe exhibits a 756-fold fluorescence turn-on response in the presence of human heparanase, allowing one-step detection of heparanase activity in real-time with a picomolar detection limit. The high sensitivity and robustness of the probe are exemplified in a high-throughput screening assay for heparanase inhibitors.Heparanase, a critical enzyme involved in the remodeling of the extracellular matrix, activates a disaccharide probe HADP to give a strong fluorescence signal. 相似文献
899.
Rate coefficients of the reaction O((3)P) + CH(3)OH in the temperature range of 835-1777 K were determined using a diaphragmless shock tube. O atoms were generated by photolysis of SO(2) with a KrF excimer laser at 248 nm or an ArF excimer laser at 193 nm; their concentrations were monitored via atomic resonance absorption excited by emission from a microwave-discharged mixture of O(2) and He. The rate coefficients determined for the temperature range can be represented by the Arrhenius equation, k(T) = (2.29 +/- 0.18) x 10(-10) exp[-(4210 +/- 100)T] cm(3) molecule(-1) s(-1); unless otherwise noted, all the listed errors represent one standard deviation in fitting. Combination of these and previous data at lower temperature shows a non-Arrhenius behavior described as the three-parameter equation, k(T) = (2.74 +/- 0.07) x 10(-18)T(2.25 +/- 0.13) exp[-(1500 +/- 90)T] cm(3)molecule(-1) s(-1). Theoretical calculations at the Becke-3-Lee-Yang-Parr (B3LYP)6-311 + G(3df,2p) level locate three transition states. Based on the energies computed with coupled clusters singles, doubles (triples) [CCSD(T)]/6-311 + G(3df,2p)B3LYP6-311 + G(3df,2p), the rate coefficients predicted with canonical variational transition state theory with small curvature tunneling corrections agree satisfactorily with the experimental observations. The branching ratios of two accessible reaction channels forming OH + CH(2)OH (1a) and OH + CH(3)O (1b) are predicted to vary strongly with temperature. At 300 K, reaction (1a) dominates, whereas reaction (1b) becomes more important than reaction (1a) above 1700 K. 相似文献
900.
The photocatalytic properties of some cyanogen-and thiocyanogen-based inorganic polymers, such as paracyanogens containing different metals (Hg, Ag, Cu), polythiocyanogens of different iodine contents, polycyanogen and poly (cyanogenthiocyanate), have been tested in two systems. Cu-containing paracyanogen and the iodine-poor polythiocyanogens catalyze the photoreduction of methylviologen under visible light, furthermore the Cu-containing paracyanogen catalyzes the photoreduction of water to hydrogen under UV irradiation.
, , , , (Hg, Ag, Cu), , (), . , , , , , , -.相似文献