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排序方式: 共有253条查询结果,搜索用时 281 毫秒
71.
L. G. Shagun O. N. Dabizha M. G. Voronkov G. F. Myachina G. I. Sarapulova T. I. Vakul'skaya L. E. Protasova A. M. Panov 《Russian Chemical Bulletin》2000,49(2):332-334
Homopolycondensation of 1-halogenopropane-2-thiones was studied; the polymers obtained were structurally characterized by
ESR, UV, and IR spectroscopy, elemental analysis, and electrochemical methods. Their molecular masses, dark conductivities,
and photoconductivities were determined. The capability for film formation on various substrates was investigated. These polymers
were found to be new organic metals (Hal=I), semiconductors (Hal=Cl and Br), and photoconductors (Hal=Cl, Br).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 330–333, February, 2000. 相似文献
72.
Francesco Ciardelli Angelina Altomare Simona Bronco Lotfi Oulderrahmania Francesco Masi 《Macromolecular Symposia》2000,156(1):147-154
After a short comparative analysis of different macromolecular ligands reported in the relevant literature, the presentation will be centered on the results obtained in the authors' laboratory using structurally defined inorganic supports in terms also of their macromolecular structure. Zeolites and mesomorphous silica can link, after proper chemical modification of their surface with MAO, unmodified metallocene complexes through cage entrapment and weak interactions, thus allowing the transfer from the solution to the solid phase. The metallocene complexes in their new phase are characterized by the catalytic behavior in olefin polymerization after activation with MAO. A decrease of productivity is generally observed depending on the type of support. The steric hindrance provided by the support is evidenced by the depression of chain transfer rate with formation of higher molecular weight polymers. Also shape selectivity is observed during copolymerization of ethylene with α‐olefins having variable size. These steric effects are released when going from HY zeolite to MCM silica. 相似文献
73.
74.
Angelina M Stoyanova 《Analytical sciences》2008,24(5):595-599
The analytical features of the reaction between N-phenylanthranilic acid (PAA) and potassium periodate in acidic medium are explored with the aim of improving the catalytic kinetic determination of iron in water samples. In the presence of Fe(II, III), PAA is oxidized by potassium periodate in a formic acid medium to form a violet-colored compound. The reaction is followed spectrophotometrically by measuring the increase in the absorbance of the oxidation product at 525 nm. The variables that affected the reaction rate were investigated and the reaction conditions were established. Calibration graphs are linear in the range of concentrations 2 - 500 ng mL(-1). As low as 10(-8) mol L(-1) Fe(II, III) can be easily determined by the fixed time method. The established catalytic method was successfully applied to the determination of iron in tap water and in pharmaceutical samples. 相似文献
75.
Angelina V. Biitseva Olha V. Hordiyenko Volodymyr A. Sukach Myhailo V. Vovk Konstantin A. Pichugin Irina S. Konovalova Oleg V. Shishkin 《Monatshefte für Chemie / Chemical Monthly》2008,139(8):939-943
The condensation of binucleophilic 3-amino-1-arylimino-1H-isoindoles with bifunctional 1-chloro-benzylisocyanates occurs regioselectively resulting in 3,4-dihydro-1,3,5-triazino[2,1-a]isoindol-2-one derivatives. The structures of the synthesized compounds were unambiguously established by NOE experiments.
Correspondence: Olha V. Hordiyenko, Chemistry Department, Kyiv National Taras Shevchenko University, 01033 Kyiv, Ukraine. 相似文献
76.
Zlata tefanac und Angelina Verbi 《Fresenius' Journal of Analytical Chemistry》1967,232(2):113-115
Ohne Zusammenfassung 相似文献
77.
Anna Maria Lapi Angelina Altomare Michele Alderighi Andrea Corti Alberto Dessy Federica Chiellini Antonella Solimando Roberto Solaro 《Journal of polymer science. Part A, Polymer chemistry》2013,51(18):3800-3809
Multiblock copolymers containing periodically spaced side‐chain carboxyl groups were obtained by a two‐step synthesis involving the preparation of ABA triblock prepolymers of ε‐caprolactone (A blocks) and ethylene glycol (B block) followed by chain extension to ABAn multiblock copolymers by reaction with pyromellitic dianhydride (PMDA). NMR analysis demonstrated the incorporation of PMDA in polymer chain and revealed the possibility of PMDA units to exist in two isomers, cisoid and transoid forms. Chain extension resulted in the incorporation of free carboxylic groups in polymer backbone and in an almost twofold increase of molecular weight. Thermal analysis indicated that the presence of PMDA residues interferes with the formation of crystalline phases by the chain‐extended polymers. The polymers were found to slowly degrade in buffer solution at 37 °C. Further, the carboxylated polymers can be processed into nanoparticulates by nanoprecipitation. Depending on the selected organic solvent, the particulate was constituted by either a monodispersed nanoparticles with average size of 150 nm or a bimodal distribution centered at about 100 nm and 7 μm. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3800–3809 相似文献
78.
Graham Kendall Ruibin Bai Jacek Błazewicz Patrick De Causmaecker Michel Gendreau Robert John Jiawei Li Barry McCollum Erwin Pesch Rong Qu Nasser Sabar Greet Vanden Berghe Angelina Yee 《The Journal of the Operational Research Society》2016,67(4):676-689
Good Laboratory Practice has been a part of non-clinical research for over 40 years. Optimization Research, despite having many papers discussing standards being published over the same period of time, has yet to embrace standards that underpin its research. In this paper we argue the need to adopt standards in optimization research. Building on previous papers, many of which have suggested that the optimization research community should adopt certain standards, we suggest a concrete set of recommendations that the community should adopt. We also discuss how the proposals in this paper could be progressed. 相似文献
79.
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