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981.
For a number of fractions and unfractionated samples of polylaurolactam, molecular weights () were measured by the light-scattering method in a mixed solvent of m-cresol with 60 vol. % 2,2,3,3-tetrafluoropropanol; intrinsic viscosities were determined in m-cresol and 96% H2SO4, and the constants of the Mark-Houwink equation were calculated. The calculated values of the characteristic ratio of unperturbed dimensions (virtually identical for m-cresol and 96% H2SO4) were compared with the respective values for polypyrrolidone and polycaprolactam. It was found that the higher frequency of the CONH-groups reduces the rigidity of the polyamide chain. 相似文献
982.
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
983.
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
984.
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
985.
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
986.
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
987.
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
988.
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
989.
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
990.
Cardiolipin is an important phospholipid present in the mitochondrial inner membrane. It plays a key function in mitochondrial respiration by interacting with many enzymes or cofactors related to oxidative phosphorylation complexes. We have determined the concentration of cardiolipin using on-line 10-N-nonyl acridine orange (NAO) dye interaction capillary electrophoresis (CE) and spectrophotometric detection with a sample throughput of 3 min. In addition to the presence of 0.1 mM NAO, the background electrolyte (BGE) composition has been set at 80% methanol-10% acetonitrile-10% H(2)O (all v/v) to provide both good solubility and the maximum absorbance enhancement at 497 nm for the NAO-cardiolipin complex as compared to NAO alone. Sample consumption for each injection is about 57 nL. A calibration curve is established from 0.5 microM to 0.1 mM with R (2) = 0.9912 with a detection limit of 0.05 microM for cardiolipin. In a blind study, actual mitochondrial cell membrane samples in the microL range before or after UV light exposure were analyzed using the CE method. Cardiolipin concentration decreased in the different parts of the membrane sample upon UV photolysis of the cells. Support for the theory that UV light can induce cardiolipin translocation from the inner membrane (IM) to the outer membrane (OM) was indicated by a significant percentage increase of cardiolipin (as measured by the cardiolipin in the OM as compared to the sum total in the OM and IM) from 30.7 +/- 2.4% before UV light photolysis to 38.3 +/- 2.2% after UV irradiation. 相似文献