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od 2020-09-20 |
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1. |
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Ion transport phenomena in polymeric electrolytes The aim of the present work is to generalize an ion transport phenomena observed in composite polymeric electrolytes using the previously developed models as well as design a new approach which would be helpful in describing changes in conductivity and lithium ion transference numbers occurring upon addition of fillers to polymeric electrolytes. The concept is based on the observation of changes in ionic associations in the polymeric electrolytes studied in a wide salt concentration range. The idea is illustrated by the results coming from a variety of electrochemical and structural data obtained for composite electrolytes containing specially designed inorganic and organic fillers.
(C) 2007 Published by Elsevier Ltd. |
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Electrochimica Acta, 54(4), 1409-1416, (2007) |
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2. |
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NMR in soft materials: A study of DMPC/DHPC bicellar system The DMPC/DHPC bicellar system at the molar ratio of 2.8:1 has been characterised by measurements of self-diffusion coefficient (using PFGSE and PFGSTE NMR sequences), differential scanning calorimetry (DSC) and small angle scattering of synchrotron radiation (SAXS). The DSC curve shows only one endothermic peak characterised by the peak temperature T-peak = 295.7 K and the onset temperature T-onset = 290.1 K. This peak can be assigned to the nematic to smectic phase transition. Below the phase transition temperature, NMR diffusion experiments indicate a two-exponential decay of the spin echo amplitude allowing two diffusion coefficients D, and D-2 to be extracted from the experimental data. The maximum size (D-max) of the bicelle determined from SAXS data using the pair distance distribution function p(r) is 11.2 nm and the bilayer thickness is 5 nm.
(C) 2007 Published by Elsevier B.V. |
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Journal of Non-Crystalline Solids, 353(47-51), 4246-4251, (2007) |
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3. |
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The effect of selected surfactants on the structure of a bicellar system (DMPC/DHPC) studied by SAXS The stabilizing or disturbing effect of different surfactants on the bicellar phase of phospholipids significantly depends on their type. The effect of different surfactants on the bicellar structure made of a mixture of phospholipids 1,2-dimyristoyl-sn-glycero-3-phosphocholine and 1.2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC/DHPC) has been studied by the small angle scattering of synchrotron radiation. The study has been performed for three surfactants: dodecyldimethyl-(hexyloxymethyl)ammonium chloride, n-undecylammonium chloride and t-octylphenoxypolyethoxyethanol (Triton X-100) introduced into a bicellar solution of DMPC/DHPC (2.8:1). The bicellar phase has been disturbed in the shortest time in the presence of dodecyldimethyl-(hexyloxymethyl)ammonium chloride in this system a transition from the bicellar to lamellar structure has been directly visible. The changes have been less pronounced in the presence of undecylammonium chloride and practically not noted in the presence of Triton X-100.
(C) 2007 Elsevier B.V. All rights reserved. |
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Journal of Molecular Structure, 846(1-3), 108-111, (2007) |
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4. |
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Changes in water status and water distribution in maturing lupine seeds studied by MR imaging and NMR spectroscopy The changes in water distribution in maturing lupin (Lupinus Luteus L.) seeds were visualized with magnetic resonance imaging (MRI). MRI data showed local inhomogeneities of water distribution inside the seed. At the late seed-filling stage the most intense signal was detected in the seed coat and the outer parts of cotyledons in the hilum area, but during maturation drying the decline in MR image intensity was faster in the outer part of the seed than in the central part. The changes in water status were characterized by NMR spectroscopy. Analyses of T-2 relaxation times revealed a three-component water proton system in maturing lupin seeds. Three populations of protons found during seed maturation, each with a different magnetic environment causing a different relaxation rate, were correlated with three fractions of water (structural, intracellular, and extracellular) that were observed during seed germination. This study provides evidence that lupin seeds have similar states of the different water components with regard to seed moisture content at two distinct physiological stages, seed maturation and germination. The unique feature of maturing lupin seeds is the presence of the high H-1-NMR signal in areas corresponding to the vascular bundles. Tissue localization of dehydrins showed the presence of dehydrin protein in the area of vascular tissue. An anti-dehydrin antibody detected three polypeptides in lupin embryos with molecular masses of 73, 43 and 28 kDa, respectively. The temporal pattern of dehydrin protein accumulation correlates well with seed desiccation.
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Journal of Experimental Botany, 58(14), 3961-3969, (2007) |
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5. |
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Proton chemical exchange in aqueous solutions of dodecylammonium chloride: Effects of micellar aggregation Proton chemical exchange was studied in aqueous solutions of dodecylammonium chloride (DDAC1) for two selected concentrations, 18 and 33 wt %. The Fourier transform Carr-Pureell-Meiboom-Gill (CPMG) NMR method combined with the Carver and Richards model for T-2 dispersion curve analysis were employed to evaluate the temperature dependence of the proton exchange rates k(ex). An increase of the energy barrier height Delta G double dagger for the proton chemical exchange between water and ammonium cation (-NH3+) was observed as the DDAC1 concentration was increased. Results are complementary to previous studies of aggregation phenomena for various n-alkylammonium chlorides.
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Journal of Physical Chemistry C, 111(43), 15613-15619, (2007) |
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6. |
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Molecular dynamics of podand studied by broadband dielectric and nuclear magnetic resonance spectroscopies Nuclear magnetic resonance (NMR) and broadband dielectric spectroscopies (BDS) were used toanalyze the molecular dynamics in P10.3H Podand. The temperature studies of NMR line and magnetic spin-lattice relaxation times accompanied by DS investigation enabled us to distinguish three main dynamical processes connected with the motions of the P10.3H Podand chains. In the low-temperature region the magnetic relaxation was associated with fast axial C-3 rotation of methyl groups. Moreover, two other independent processes were observed and interpreted as (i) segmental motion of both oxyethylene and ethylene units, and (ii) the overall motion involved in the melting process.
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Macromolecular Chemistry and Physics, 208(19-20), 2121-2127, (2007) |
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7. |
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Alpha(c) relaxation of the constrained amorphous phase : polyethylene-chalk composites The study presents properties of polyethylene commercial products with special attention to properties of a 'semi-ordered' amorphous phase. Although, one can hardly prove the existence of such an interphase, the results description based on the idea of coexistence of two amorphous fractions ('real' and 'semi-ordered') in one system gives a broader understanding of the relationship between product history and morphology of the resultant engineering products. Their supermolecular structures were explored using positron annihilation lifetime spectroscopy (PALS), calorimetry (DSC) and mechanical spectroscopy in a tensile and a torsion mode (DMTA). The stability of these structures is also discussed based on a simple statistical analysis of the thermodynamic and structural parameters. The study exhibited that chalk did not disturb too much the crystalline domains of PE-LD whereas it influenced the interphase. Mechanical study showed that such a product is not stable during long time storage. The comparison with previous results, obtained for PE-carbon black composites, revealed differences in the morphologies and the alpha(c) relaxations of PE chains, observed in the composites including various fillers.
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Journal of Thermal Analysis and Calorimetry, 90(1), 201-208, (2007) |
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8. |
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SAXS studies of human protein HC (alpha1-microglobulin) Protein HC is a low molecular weight heterogeneous glycoprotein widely distributed in human body fluids and belonging to the lipocalin superfamily. The monomer contains a single (183 amino acid residues long) peptide chain with 3 cysteine residues (2 of which form a disulfide bridge) and is glycosylated. The molecular mass of the glycosylated protein is about 27 kDa.
Native gel electrophoresis results revealed partial oligomerisation of protein HC, which therefore was analysed by gel filtration. Two forms (monomer and dimer) of the protein HC were isolated. The SAXS data were recorded on an X33 camera using synchrotron radiation (lambda=0.15 nm) at X33 beamline at the DORIS storage ring of DESY (Hamburg, Germany). Solution scattering results permitted determination of the structural parameters of both forms of the protein studied. The monomer of protein HC is characterised by a radius of gyration R-G = 2.20 nm and D-max =63 nm and the dimer by R-G=2.99 nm and D-max = 9.5 nm.
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Protein and Peptide Letters, 14(5), 425-429, (2007) |
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9. |
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Application of microscopic MR for evaluation of cartilage repair Magnetic resonance imaging is gold standard for noninvasive evaluation of articular cartilage damage and has been also used for monitoring cartilage repair. The aim of this study was to find correlation between histological microscopy and microscopic MR in evaluation of the repair of osteochondral defects in articular cartilage. Study was based animal model (rabbit). The cartilage repair process was evaluated histology and micro MR. Most of the defects were filled with fibrocartilage and fibrous tissue formed. Both methods were equally efficient to show repair tissue thickness, subchondral bone reconstruction and disintegration. Result of observation by both histological and MR microscopy and showed good correlation. Micro MR is promising evaluation tool for cartilage repair monitoring. Results of micro MR correlate well with standard microscopy.
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Chirurgia Narządów Ruchu i Ortopedia Polska, 72(3), 193-9, (2007) |
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(Pobrane: 2020-10-21) |
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10. |
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Interactions of cationic surfactants with DPPC The effects of different cationic surfactants (n-undecylammonum chloride, UDACl and dodecyldimethyl (dodecyloxymethyl) ammonium chloride, DDMDDACl) on fully hydrated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) vesicles have been studied. In the studied systems the molar ratio (x) of DPPC/surfactant ranged between x=0.0164-0.82 and from x=0.0352-1.76 for DPPC/DDMDDACl and DPPC/UDACl, respectively. For both systems, the enthalpy associated with the phase transition significantly decreases even at the lowest surfactant concentration. Also the main phase transition temperature is shifted towards lower temperatures.
The structural parameters of the phases have been characterised by small angle X-ray scattering (SAXS). The SAXS results have proved that UDACl at x=0.0352 molar ratio significantly influences the DPPC lamellar structure, while its total disappearance was observed for x=0.176. The presence of DDMDDACl causes a total disappearance of the DPPC lamellar structure already at the lowest molar ratio (x=0.0352). Each surfactant in the system with DDPPC leads to a mixed micellar phase formation.
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Journal of Thermal Analysis and Calorimetry, 88(2), 395-399, (2007) |
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11. |
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Thermal and dynamic mechanical analysis of cross-linked poly(esterurethanes) New cross-linked poly(esterurethanes) (PEU) based on unsaturated olygo(alkyleneester)diol (OAE), 4,4'-diphenylmethane diisocyanate (MDI) and styrene or methyl methacrylate as curing monomers were prepared. The synthesis of PEU was performed in two steps. In the first step OAE was obtained from adipic acid, maleic anhydride and ethylene glycol. In the second step a prepolymer was obtained in a reaction of OAE with different amounts of 4,4'-diphenylmethane diisocyanate followed by crosslinking using previously mentioned curing monomers. The influence of structure of the poly(esterurethanes) on thermal and dynamic mechanical properties is studied. Thermogravimetric analysis shows that cross-linked poly(esterurethanes) demonstrate high thermal stability. Moreover the dynamic mechanical thermal analysis shows that the presence of styrene cross-linking chains in polymers lead to the phase separation in cross-linked poly(esterurethanes).
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Journal of Thermal Analysis and Calorimetry, 88(2), 419-423, (2007) |
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12. |
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Electric-field-gradient tensor and boron site resolved 11B NMR in single-crystalline YB12 B11 NMR measurements on a single crystal of YB12 have been performed at room temperature at a frequency of 128.4 MHz. The electric-field-gradient (EFG) tensor components and the principal axes calculated previously by first-principles methods have been verified experimentally. Three magnetically different boron-atom groups in the B12 cluster were clearly observed for the crystal orientation used in this work. This distinction results from different EFG-tensor orientations with respect to magnetic field and not from different quadrupolar splittings (νQ) or asymmetry-parameter values (η). The magnetically different boron atoms have been identified through the calculated angle dependence of the satellite transitions (0°–360°). Very satisfactory agreement between the calculated and experimental angular dependencies of the EFG tensor has been obtained. Similarly, the quadrupolar splittings and asymmetry parameters agree very well with those previously determined from NMR measurements on a powder sample of YB12.
(C)2007 American Physical Society |
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Physical Review B - Condensed Matter and Materials Physics, 75(18), 184102, (2007) |
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13. |
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Water uptake and distribution in germinating lupine seeds studied by magnetic resonance imaging and NMR spectroscopy Magnetic resonance imaging (MRI) was used to study temporal and spatial water uptake and distribution in germinating lupine (Lupinus Luteus L.) seeds. During 24 h of imbibition, water was unevenly distributed within the seed and some anatomical parts were more hydrated than others. Water entered the seed through the hilum and micropyle. The embryonic axis was the first to show hydration followed by seed coat and later cotyledons. The changes in water status were characterized by NMR spectroscopy. Analyses of T-2 relaxation times revealed a three-component water proton system (structural, intracellular and extracellular water) in germinating lupine seeds. The data on the components of transverse relaxation time studies indicated the complex exchange processes taking place between water components inside lupine seed over first 2.5 h of hydration, with a distinguished increase in structural water and decrease in other components. This speaks in favor of the high water-absorbing capacity of lupine seeds as related to high protein content. Germination was accompanied by swelling of protein bodies and changes in the organization of stored reserves with gradual disappearance of protein from the cells.
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Physiologia Plantarum, 130(1), 23-32, (2007) |
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14. |
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Thermal study of four irradiated imidazoline derivatives in solid state Four imidazoline derivatives: antazoline (AN), naphazoline (NN), tymazoline (TM), xylometazoline (XM), in the form of hydrochlorides in solid phase have been subjected to high energy e-beam irradiation from an accelerator (similar to 10 MeV) at a dose varied from 25 to 200 kGy. The effects of the irradiation have been assessed by DSC, X-ray diffraction, FTIR, EPR and TLC.
The standard sterilisation dose of 25 kGy has been found to produce changes in the properties of one derivative (XM), two other ones (AN and TM) have been found sensitive to doses > 100 kGy, whereas NN has been resistant to irradiation in the whole range studied (25-200 kGy). EPR results indicated that the changes taking place in the therapeutic substances studied are related to radical formation. The irradiation induced changes in colour, a decrease or increase in the melting point, changes in the XRD pattern, small changes in the shape of FTIR peaks and the presence of radiolysis products. The XM compounds cannot be sterilised by irradiation because of the radiation induced changes in its physico-chemical properties.
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Journal of Thermal Analysis and Calorimetry, 88(2), 337-342 , (2007) |
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15. |
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Comparative studies of p6m siliceous mesostructures by powder X-ray diffraction and nitrogen adsorption Two-dimensional mesostructures with p6m symmetry such as MCM-41 and SBA-15 are the subject of intensive studies by using nitrogen and argon adsorption, transmission electron microscopy, and powder X-ray diffraction/scattering techniques. The latter may involve the X-ray diffraction (XRD) or small angle X-ray scattering (SAXS) measurements. The XRD/SAXS patterns for the aforementioned ordered mesostructures often exhibit four or more reflections, the most intensive one, 1 0 0 peak, and three less intensive peaks, 1 10, 2 0 0, 2 1 0. So far, analysis of these patterns was usually limited for the evaluation of the unit cell parameter and the identification of the observed peaks. In this work we present an attempt to analyze the XRD/SAXS patterns by including not only the position of observed peaks but also their intensity. It is shown that the intensity of these peaks, especially I 1 0 peak, depends on the ratio of the pore diameter to the unit cell parameter. In particular, this dependence was studied for the intensity ratio of 1 10 and 2 0 0 peaks assuming 2 0 0 peak as a reference reflection because of its nearness to I 10 peak (which minimizes the influence of other factors than the structural ones on the 1 1 0/2 0 0 intensity ratio analysis) and similar intensity to that of 1 1 0 peak. The values of the 1 1 0/2 0 0 intensity ratio were determined for many MCM-41 and SBA-15 samples and analyzed in relation to the pore width/ unit cell ratio, where the pore width was estimated on the basis of nitrogen adsorption data or by the XRD/SAXS structure modeling. Comparative analysis of this intensity ratio for numerous MCM-41 and SBA-15 samples allows for a quick estimation of the pore width and provides some information about hexagonality of mesopores in these materials.
(C) 2007 Elsevier B.V. All rights reserved. |
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Applied Surface Science, 253(13), 5682-5687, (2007) |
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16. |
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Cation dynamics in pyridinium nitrate and bis-thiourea pyridinium nitrate inclusion compound studied by 2H NMR spectroscopy H-2 NMR ( nuclear magnetic resonance) line-shape measurements were performed over a wide temperature range for pyridinium nitrate (d(5)PyH) NO3 and bis-thiourea pyridinium nitrate inclusion complex T-2(d(5)PyH) NO3 in order to compare the dynamics of d(5)-pyridinium cation in both compounds. It was revealed that in both systems the pyridinium cation undergoes reorientations about the axis perpendicular to its plane, among inequivalent potential energy barriers. However, in (d(5)PyH) NO3 (no phase transition) the population of the deepest minima decreases monotonically up to the melting point, whereas in T-2(d(5)PyH) NO3 (two phase transitions) this population decreases rapidly in a transition to the high-temperature phase and its value does not depend on temperature. In bis-thiourea pyridinium nitrate inclusion compound the out-of-plane motion of the cation is also found in the intermediate- and high-temperature phases, and the amplitudes of the motion are equal to 20 degrees and 35 degrees, respectively. On the basis of the assumptions of these models, it is possible to reproduce the experimental H-2 NMR line shapes in an excellent way.
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Journal of Physics: Condensed Matter, 19(15), 156220, (2007) |
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17. |
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SAXS study of selected cationic surfactant influence on the DSPC-based model phospholipid system The phase behaviour of lipid bilayer systems prepared with 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) with dodecyldimethyl(benzyloxymethyl)ammonium chloride (BzMDDAC) (at concentrations 0.1, 1 and 5%) has been studied by small angle X-ray scattering and differential scanning calorimetry. The SAXS and DSC results of the hydrated 10% DSPC revealed one typical phase transition corresponding to melting of the hydrocarbon chains at 5 5 degrees C. In the system of 10% DSPC - 0.1% BzMDDAC the main transition was somewhat shifted towards lower temperatures, while at 1% concentration of BzMDDAC in the mixture, the lamellar phase disappeared, as evidenced by SAXS and DSC. The increase in BzMDDAC concentration to 5% in the mixture with 10% DSPC resulted in formation of a new lamellar phase.
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Solid State Phenomena, 130, 257-262, (2007) |
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18. |
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Poziom adenylanów i nukleotydów pirydynowych w rozwijających się i dojrzewających nasionach grochu (Pisum Sativum L. ) Zapotrzebowanie na energię zmienia się podczas rozwoju nasion, począwszy od wzrostu merystematycznego we wczesnych stadiach, aż po fazę magazynowania, charakteryzującą się wysoką aktywnością biosyntetyczną. Także aktywność oddechowa zarodków zmienia się zasadniczo podczas rozwoju nasion [KOLLÖFFEL, MATTHEWS 1983]. Ważnym wskaźnikiem statusu energetycznego tkanki jest poziom nukleotydów adenylowych i ich wzajemny stosunek. Stan energetyczny tkanki określa wartość tzw. ładunku energetycznego (adenylate energy charge - AEC). Opisuje on nasycenie układu adenylanów w bezwodnikowe wiązania fosforanowe. Innym ważnym źródłem energii, regulującym stan równowagi energetycznej i transport elektronów, jest zawartość nukleotydów pirydynowych. Celem pracy było określenie stanu metabolicznego zarodków izolowanych z rozwijających się i dojrzewających nasion grochu Pisum sativum na podstawie wyników oznaczeń ładunku energetycznego oraz poziomu nukleotydów adenylowych i pirydynowych.
POZIOM ADENYLANÓW I NUKLEOTYDÓW PIRYDYNOWYCH W ROZWIJAJĄCYCH SIĘ I DOJRZEWAJĄCYCH NASIONACH GROCHU (Pisum sativum L.). Available from: http://www.researchgate.net/publication/236902532_POZIOM_ADENYLANW_I_NUKLEOTYDW_PIRYDYNOWYCH_W_ROZWIJAJCYCH_SI_I_DOJRZEWAJCYCH_NASIONACH_GROCHU_(Pisum_sativum_L.) [accessed Sep 15, 2015].
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Zeszyty Problemowe Postępów Nauk Rolniczych, 522, 485-491, (2007) |
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(Pobrane: aktualizowanie) |
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Zaktualizowano: podstrony 2021-06-21 / bazę danych: 2024-11-28 by Webmaster: Zbigniew Fojud