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21.
In the Castelporziano (Rome) protected area the inputs of atmospheric heavy metals on the soil-plant system were evaluated by the analysis of stem-flowing water from Quercus ilex L. The heavy metals detected in the soil under the canopies exhibited higher concentrations near to the tree trunks, highlighting the tree's capacity to concentrate such polluting substances. Microbial biomass, its specific respiration and the biomass calculated as a percentage of total soil organic matter, were utilised as indicators of the state of the soil and consequently also its quality with respect to heavy metal contamination. 相似文献
22.
The determination of safe sampling volumes of benzene and acetone on air samplers filled with Porapak Q, Chromosorb 101, 102 and 103 is described. Two direct methods are employed; one method is based on frontal chromatography, while the second one is a concentration method followed by thermal desorption. The results are compared to those determined by the indirect pulse chromatographic method. The safe sampling volumes determined by the direct methods were in accordance. The indirect method gives slightly different values; however, this procedure is carried out at "infinite dilution". The effect of the pollutant concentration on the safe sampling volumes was also examined. The values decrease with increasing pollutant concentration. 相似文献
23.
E. Fontana E. Pianezzola G. Basileo M.Strolin Benedetti 《Journal of chromatography. A》1994,660(1-2):293-298
A sensitive and selective high-performance liquid chromatographic method for the determination of FCE 24928 (4-amino-androsta-1,4,6-triene-3, 17-dione) in human plasma is reported. The drug was extracted from buffered (pH = 8) plasma samples with methylene chloride-isooctane, then analysed by reversed-phase liquid chromatography. Quantitation was achieved by ultraviolet detection of the eluate at 238 nm. Blank plasma samples from humans, dog and rat assayed as described showed no significant peak at the retention time of the compound of interest. The suitability of the method for in vivo samples was tested by measuring the plasma levels of FCE 24928 in rats that received oral doses of the test compound. 相似文献
24.
Mordini A Bindi S Pecchi S Degl'Innocenti A Reginato G Serci A 《The Journal of organic chemistry》1996,61(13):4374-4378
The base-promoted isomerization of benzyl oxiranyl ethers was investigated. In particular it was shown that the reaction may proceed toward two main regioisomeric products: a benzyl vinyl ether or a 2-aryl-3-(hydroxyalkyl)oxetane, depending on subtle variations in the substitution on the phenyl ring. Disubstituted oxetanes were obtained in a stereoselective manner, thus providing a good entry to this class of synthetically useful compounds. 相似文献
25.
Sonja Strah Branko Stanovnik Simona Goli
Grdadolnik 《Journal of heterocyclic chemistry》1997,34(1):263-267
Alkyl 2-(2-benzoyl-2-ethoxycarbonyl-1-ethenyl)amino-3-dimethylaminopropenoates 4a,b were prepared. They react with C-nucleophiles such a 2-pyridinylacetonitrile 5 and methyl-2-quinolinylacetate 8, cyclohexane-1,3-dione 10 and its derivatives 12 and 14, resorcinol derivative 16 , 2-naphtol 18, 2-pyranone derivatives 20 and 22, and 4-hydroxypyridin-2(1H)-one 24, to form substituted amino derivatives of quinolizine 6, benzo[c]quinolizine 9, tetrahydrobenzopyran-2-one 11, 13, 15 , naphto[2,1-b]pyran-3-one 19 , pyranopyranones 21, 23, and pyrano[3,2-c]pyridine 25. 相似文献
26.
Gabriella Ieronimo Alessandro Mondelli Francesco Tibiletti Angelo Maspero Giovanni Palmisano Simona Galli Stefano Tollari Norberto Masciocchi Kenneth M. Nicholas Silvia Tagliapietra Giancarlo Cravotto Andrea Penoni 《Tetrahedron》2013
The thermal reaction between nitrosoarenes and alkynes under alkylating conditions produces N-alkoxyindoles as the major products in moderate to good yields and excellent regioselectivity. Various electrophiles are used affording different N–O-protected hydroxyindoles in a multi-component fashion. Privileged acetylenic substrates used in reactions with substituted nitrosoarenes are arylalkynes or propiolates. Potentially bioactive compounds and other classes of highly functionalizable indole products were prepared. Reactions between o-carbomethoxy-nitrosoarenes and arylacetylenes provided tricyclic compounds containing an acylaziridine indoline skeleton. 相似文献
27.
Copolymer composition, distribution and molecular size of the comonomer influence the final properties of polymer materials. Such influence can be followed from the effect on the chain conformation in solution determined from the scaling law between radius of gyration and molecular weight. 相似文献
28.
Caterina Viglianisi Stefano Menichetti Giulio Assanelli Maria Carmela Sacchi Incoronata Tritto Simona Losio 《Journal of polymer science. Part A, Polymer chemistry》2012,50(22):4647-4655
A new family of ethylene‐based copolymers with controlled amounts of a norbornene comonomer (NArOH) bearing a stabilizing antioxidant functionality (2,6‐di‐tert‐butyl phenol) was prepared. Due to unavoidable exo/endo equilibrium operative in NArOH comonomer, a complete and detailed NMR assignment of the structure of the prepared ethylene/NArOH copolymers was carried out for the determination of the exo/endo ratio inside the polymer. These novel functionalized comonomers can be considered suitable starting material for preparing ethylene‐based copolymers, with tunable comonomer content, as non‐releasing macromolecular antioxidant additives for specific application in safe food and/or drug packaging © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
29.
The structures of archaeal glycerophospholipids and glycolipids are unique in that they consist of phytanyl substituents ether linked to the glycerol backbone, imparting stability to the molecules. In this contribution, we described multiple-stage linear ion-trap combined with high resolution mass spectrometry toward structural characterization of this lipid family desorbed as lithiated adduct ions or as the [M−H]− and [M−2H]2− ions by ESI. MSn on various forms of the lithiated adduct ions yielded rich structurally informative ions leading to complete structure identification of this lipid family, including the location of the methyl branches of the phytanyl chain. By contrast, structural information deriving from MSn on the [M−H]− and [M−2H]2− ions is not complete. The fragmentation pathways in an ion-trap, including unusual internal loss of glycerol moiety and internal loss of hexose found for this lipid family were proposed. This mass spectrometric approach provides a simple tool to facilitate confident characterization of this unique lipid family. 相似文献
30.
S. Sivestrini P. Riello I. Freris D. Cristofori F. Enrichi A. Benedetti 《Journal of nanoparticle research》2010,12(3):993-1002
The synthesis, morphology and luminescence properties of europium(III)-doped zirconium carbonates prepared as bulk materials
and as silica-supported nanoparticles with differing calcination treatments are reported. Transmission electron microscopy
and X-ray diffraction analyses have, respectively, been used to study the morphology and to quantify the atomic amount of
europium present in the optically active phases of the variously prepared nanomaterials. Rietveld analysis was used to quantify
the constituting phases and to determinate the europium content. Silica particles with an approximate size of 30 nm were coated
with 2 nm carbonate nanoparticles, prepared in situ on the surface of the silica core. Luminescence measurements revealed
the role of different preparation methods and of europium-doping quantities on the optical properties observed. 相似文献