共查询到20条相似文献,搜索用时 750 毫秒
1.
G. A. Korneeva I. I. Kerov Z. Kh. Ibragimova V. I. Kurkin K. L. Makovetsky E. V. Slivinsky 《Russian Chemical Bulletin》1998,47(2):360-362
It was found that carboxylation of norbornene (nbn) in the presence of the PdCl2−PPh3−HCl catalytic system is accompanied by alternating copolymerization ofnbn with carbon monoxide to form norbornanecarboxylic acid (yield ∼20%) and anbn-CO copolymer (yield ∼80%,M
w=1600,M
w/M
n=1.6). The PdII salt of poly(norbornaneketone)carboxylic acid is a highly active catalyst for the carbomethoxylation of propylene.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 368–370, February, 1998. 相似文献
2.
The iron-inulin complex, which could be applied as a parenteral hematinic agent, is studied by physical techniques. Electron
microscopy shows that the complex contains very small particles that are approximately spherical and 10–30 nm in diameter.
The examination reveals the presence of an electron-transparent sheath, probably consisting of linked inulin oligomers with
M
w ∼ 3000 g mol−1, around the electron-dense, ironcontaining core of the FeOOH particles. FTIR spectroscopy suggests the existence of stronger
hydrogen bonds, which are formed in the complexes between FeOOH and oligosaccharides, compared to the hydrogen bond in the
initial compounds. A gel filtration technique on a Sephadex column showed conclusively that a large proportion of combined
inulin oligomers with M
w ∼ 1500 g mol−1 as secondary fractions are present in complexes. These low-molecular-weight inulin fractions have a significant influence
on the complex stability.
The text was submitted by the authors in English. 相似文献
3.
O. P. Charkin 《Russian Journal of Inorganic Chemistry》2011,56(11):1775-1781
The equilibrium geometric parameters and energetic and spectroscopic characteristics of low-lying conformers for several series
of model cage-substituted (mixed) borane, alane, and gallane closo-dianions M
i
M′12 − i
H122−(M, M′ = B, Al, Ga), as well as of “bare” gallium-aluminum anions Ga
i
Al12−i
− with i = 0–12, were calculated within the B3LYP approximation of the density functional theory using 6–31G* and 6–311+G** basis
sets. Differences in structure and stability between alanoborane clusters of similar composition are revealed. In clusters
where the M and M’ heteroatoms are close in size and electronegativity (in gallonoalanes and gallium-aluminum anions), successive
substitutions of M′ for M are accompanied by small energy changes and occur quasi-stochastically in different positions of
the cage. When the substituents are significantly different (in alanoboranes), mixed clusters are unstable against disproportionation
into homonuclear “predecessors” M12H122− and M′12H122−, and the most favorable M
i
M′12 − i
H122− structures among them are those in which M
i
M′12 − i
the cages are subdivided into homonuclear “subclusters” M
i
and M′t′12−i
with a maximal number of homonuclear bonds (M-M and M′-M′) and a minimal number of heteronuclear bonds (M-M′). 相似文献
4.
Y. S. Murillo L. Giraldo J. C. Moreno-Piraján 《Journal of Thermal Analysis and Calorimetry》2011,104(2):555-559
A way to calculate the enthalpic contributions of each component of the mixture of activated carbon and water to the immersion
enthalpy using the concepts of the solution enthalpies is presented. By determining the immersion enthalpies of a microporous
activated carbon in water, with values that are between –18.97 and −27.21 Jg−1, from these and the mass ratio of activated carbon and water, differential enthalpies for the activated carbon,
ΔHDIFacH_{{\rm DIF}_{\rm ac}} and water, ΔHDIFwH_{{\rm DIF}_{\rm w}} are calculated, and values between –15.95 and –26.81 Jg−1 and between –19.14 and –42.45 Jg−1, respectively are obtained. For low ratios of the mixture, the components’ contributions to the immersion enthalpy of activated
carbon and water differ by 3.20 Jg−1. 相似文献
5.
S. Ch. Gagieva T. A. Sukhova D. V. Savinov V. A. Tuskaev K. A. Lyssenko N. M. Bravaya Yu. N. Belokon’ B. M. Bulychev 《Russian Chemical Bulletin》2006,55(10):1794-1802
New representatives of chelate-type titanium(IV) salicylideneaniline complexes with bis(5-methyl-2-furyl)methyl substituents in the aniline fragment are synthesized. In
the presence of poly(methylalumoxane), these complexes catalyze ethylene and propylene polymerization. The effect of the position
of substituents in the ligands on the activities of the catalysts is studied. High-molecular-weight linear polyethylene (M
w ≈ 172200–300000, M
w/M
n ≈ 2–3) and high-molecular-weight atactic elastic polypropylene (M
w ≈ 1000000, M
w/M
n ≥ 7.0) are obtained.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1730–1737, October, 2006. 相似文献
6.
L. E. Gusel’nikov E. N. Buravtseva N. V. Ushakov V. G. Lakhtin L. A. Parshkova N. A. Kuyantseva E. A. Chernyshev 《Russian Chemical Bulletin》2010,59(7):1376-1380
Dehalogenation of 1-[(chloro)(ethyl)(methyl)silyl]-2-[chloro(climethyl)silyl]ethane with the alkali metal vapors gave l-ethyl-l,2,2-trimethyl-1,2-disilacyclobutane.
Its spontaneous ring-opening polymerization at room temperature afforded an amorphous linear polymer with T
g = −75 °C, M
w = 454 200–512 800, and M
w/Mn = 1.87–2.82. According to NMR data, the backbone of the polymer consists of alternating monomeric units linked in the “head-to-tail”
(SiMe 2CH2CH2SiMeEtSiMe2CH2CH2SiMeEt) and “head-to-head” ways (SiMeEtCH2CH2SiMe2SiMe2CH2CH2SiMeEt) in a ratio of 1: 0.96. Spontaneous copolymerization of the above disilacyclobutane with 1,1,2,2-tetramethyl-l,2-disilacyclobutane
gave partially crystalline copolymers with different glass transition and melting temperatures, depending on the ratio of
the components in the reaction mixture. The compositions of the copolymers were examined by 1H, 13C, and 29Si NMR spectroscopy. 相似文献
7.
Nashwa M. H. Rizk 《Mikrochimica acta》2002,138(1-2):53-58
The construction and electrochemical response characteristics of poly(vinyl) chloride matrix membrane sensors for menadione
(vitamin K3) are described. Membranes incorporating the ion association complexes of menadione anion with bathophenanthroline nickel(II)
and iron(II) as electroactive materials show linear response for menadione over the range 10−1–10−5 M with anionic slopes of 58.2–51.4 mV per concentration decade. Both sensors exhibit fast response time (20–30 s), low detection
limit (2 × 10−5 M), good stability (4–6 weeks) and selectivity coefficient (10−1–10−3). Direct potentiometric determination of menadione under static and hydrodynamic mode of operations shows average accuracies
of 98.8 and 98.5% with relative standard deviations of 0.6% and 1.3%, respectively. Application of the method for the determination
of menadione in human plasma gives favourable results compared with those obtained by the standard spectrophotometric method.
Received February 26, 2001. Revision October 1, 2001. 相似文献
8.
Eric Da Silva Cécile F. Rousseau Isabelle Zanella-Cléon Michel Becchi Anthony W. Coleman 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(1-2):53-59
Electrospray Ionization Mass Spectrometry (ESI/MS) has been used to determine the association constants (KAs) and binding stoichiometries for parent para-Sulphonato-calix[n]arenes and their derivatives with bovine serum albumin (BSA). KA values were determined by titration experiments using a constant concentration of protein. KA measurements were carried out in a methanol–formic acid solution. 5,11,17,23–tetra-Sulphonato-calix[4]arene (1a) and 25-mono-(2-aminoethoxy)-5,11,17,23-tetra-Sulphonato-calix[4]arene (1d) interact strongly with BSA showing 3 non-equivalent binding sites with KA1 = 7.69 × 105 M−1, KA2 = 3.85 × 105 M−1, KA3 = 0.33 × 105 M−1 and KA1 = 1.69 × 105 M−1, KA2 = 2.94 × 105 M−1, KA3 = 0.60 × 105 M−1, respectively. The strength of the interactions between the calixarene and BSA is inversely proportional to the size of macrocyclic
ring: n = 4 > n=6>>n=8. 相似文献
9.
Regions of existence were determined for various types of poly- and monocrystalline solid solutions (Ln3[ScyM2−y]M3O12; {Ln3−xScx}[ScyM2−y]M3O12; Ln3[LnzScyM2−y−z] M3O12; Ln=Y, Gd; M=Ga, Al) by analyzing the diagrams rVIII−rVI (rVI are weighted mean dodecahedral and octahedral radii, respectively). We found the position of congruently melting compositions
in rVIII−rVI coordinates and optimal compositions for obtaining Nd3+- and Cr3+-doped crystals. The structure of the congruently melting composition was found to be formed of “equilibrium” polyhedra, which
need not be stabilized. It is shown that a congruently melting composition, which is absent in the original matrix, may be
achieved by isomorphous substitutions at certain positions of the structure. The most probable mechanisms of formation of
poly- and monocrystalline solid solutions with garnet structure are suggested using the calculated binodal curves of decomposition.
M. V. Lomonosov Moscow Academy of Fine Chemical Technology. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 5, pp. 23–33, September–October, 1994.
Translated by O. Kharlamova 相似文献
10.
Mariano Velázquez-Rivera Donald A. Palmer Richard M. Kettler 《Journal of solution chemistry》2006,35(12):1699-1730
This study measures the osmotic coefficients of {xH2SO4 + (1−x)Fe2(SO4)3}(aq) solutions at 298.15 and 323.15 K that have ionic strengths as great as 19.3 mol,kg−1, using the isopiestic method. Experiments utilized both aqueous NaCl and H2SO4 as reference solutions. Equilibrium values of the osmotic coefficient obtained using the two different reference solutions
were in satisfactory internal agreement. The solutions follow generally the Zdanovskii empirical linear relationship and yield
values of a
w for the Fe2(SO4)3–H2O binary system at 298.15 K that are in good agreement with recent work and are consistent with other M2(SO4)3–H2O binary systems. 相似文献
11.
I. V. Baklanova V. N. Krasil’nikov L. A. Perelyaeva O. I. Gyrdasova 《Theoretical and Experimental Chemistry》2011,47(4):215-218
lid solutions Ti1−x
M
x
O2−x/2 in the anatase and rutile forms were obtained from the precursors Ti1−x
M
x
(OCH2CH2O)2−x/2 at T = 450–900 °C. The temperature and concentration dependence of the phase transformation of anatase to rutile in Ti1−x
M
x
O2−x/2 was investigated by Raman spectroscopy. It was shown that the anatase phase is stabilized most effectively by the Eu3+ dopant. 相似文献
12.
J. Melsheimer 《Colloid and polymer science》1972,250(2):97-101
Zusammenfassung Ein vonZimm undCrothers auf ein rotierendes System angewandtes Me?prinzip zur Bestimmung der Viskosit?t im Bereich kleiner Geschwindigkeitsgef?lle
wurde so modifiziert, da? ohne direkte Ver?nderung am Rotationsviskosimeter (z. B. Wechsel des Rotors) die relative Viskosit?t
in Abh?ngigkeit vom Geschwindig-keitsgef?lle untersucht werden konnte.
Die Messungen erstreckten sich über einen Geschwindigkeitsgef?llebereich von 0,2 bis 2[s−1] und einen Schubspannungsbereich von 1,1·10−3 bis 13,2·10−3[dyn cm−2]. Testmessungen an einem anionisch polymerisierten Polystyrol (M
n
=81200) in Benzol bei 25 °C stimmten mit den Daten aus Vergleichsuntersuchungen der IUPAC überein. Beim Polyvinylcarbazol
(M
w
=6,85·106) in Benzol konnten die im Kapillarviskosimeter erzielten Werte für die relative Viskosit?t im Rotationsviskosimeter best?tigt
werden. Au?erdem wurde keine Abh?ngigkeit der Viskosit?t vom Gesohwindigkeitsgef?lle bei den Messungen im Rotationsviskosimeter
festgestellt.
Herrn Prof. Dr.K. Ueberreiter danke ich für sein Interesse an dieser Arbeit. HerrnD. Ziegler danke ich für die Unterstützung beim Aufbau des Rotationsviskosimeters.
Diese Arbeit wurde von der Deutschen Forschungs-gemeinschaft finanziert, wofür ich meinen Dank ausspreche. 相似文献
Summary The rotating viscosimeter developed byZimm-Crothers for viscosity measurements under low stress rate was so modified that without any direct change in the viscosimeter (e.g. change of rotors) the dependence of relative viscosity on shear rate could be investigated. The measurements spanned a range of 0,2–2 [s−1] for the rate of shear and a stress range of 1,1·10−3 to 13,2·10−3 [dyne·cm−2]. Test measurements on an anionic polymerized polystyreneM n=81200) in benzene at 25 °C were in agreement with reference measurements of IUPAC. For polyvinylcarbazole (M w=6,85·106) the data obtained by rotating viscosimeter agreed with measurements by the capillary viscosimeter. Furthermore the data obtained by the rotating viscosimeter did not show any dependence of the viscosity on the rate of shear.
Herrn Prof. Dr.K. Ueberreiter danke ich für sein Interesse an dieser Arbeit. HerrnD. Ziegler danke ich für die Unterstützung beim Aufbau des Rotationsviskosimeters.
Diese Arbeit wurde von der Deutschen Forschungs-gemeinschaft finanziert, wofür ich meinen Dank ausspreche. 相似文献
13.
Joanna Wiśniewska 《Transition Metal Chemistry》2007,32(1):107-111
The kinetics of the oxidation of promazine by trisoxalatocobaltate(III) were studied in the presence of a large excess of
the cobalt(III) in tris buffer solution using u.v.–vis spectroscopy ([CoIII] = (0.6 − 2) × 10−3
M, [ptz] = 6 × 10−5
M, pH = 6.6–7.8, I = 0.1 M (NaCl), T = 288−308 K, l = 1 cm). The reaction proceeds via two consecutive reversible steps. In the first step, the reaction leads to formation of cobalt(II) species and a stable cationic
radical. In the second step, cobalt(III) is reduced to cobalt(II) ion and a promazine radical is oxidized to the promazine
5-oxide. Linear dependences of the pseudo-first-order rate constants (k
1 and k
2) on [CoIII] with a non-zero intercept were established for both redox processes. Rates of reactions decreased with increasing concentration
of the H+ ion indicating that the promazine and its radical exist in equilibrium with their deprotonated forms, which are reactive
reducing species. The activation parameters for reactions studied were as follows: ΔH≠ = 44 ± 1 kJ mol−1, ΔS≠ = −100 ± 4 JK−1 mol−1 for the first step and ΔH≠ = 25 ± 1 kJ mol−1, ΔS≠ = −169 ± 4 J K−1 mol−1 for the second step, respectively. Mechanistic consequences of all the results are discussed. 相似文献
14.
The reaction of [M(L)]Cl2 · 2H2O (M = Ni2+ and Cu2+, L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane) with 1,1-cyclobutanedicarboxylic acid (H2-cbdc) generates 1D and 2D hydrogen-bonded infinite chains [Ni(L)(H-cbdc−)2] (1) and [Cu(L)(H-cbdc−)2] (2). (H-cbdc− = cyclobutane-1-carboxylic acid-1-carboxylate). These complexes have been characterized by X-ray crystallography, spectroscopy,
and cyclic voltammetry. The crystal structure of 1 shows a distorted octahedral coordination geometry around the nickel(II) ion, with four secondary amines and two oxygen atoms
of the H-cbdc− ligand at the trans position. In 2, the coordination environment around the central copper(II) ion shows a Jahn–Teller distorted octahedron with four Cu–N bonds
and two long Cu–O distances. The cyclic voltammogram of the complexes undergoes two one-electron waves corresponding to MII/MIII and MII/MI processes. The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature
of the axial H-cbdc− ligand. 相似文献
15.
N. M. Storozhok N. P. Medyanik A. P. Krysin I. P. Pozdnyakov S. A. Krekov 《Kinetics and Catalysis》2012,53(2):162-171
The kinetics of the initiated oxidation of a model lipid (methyl oleate has been investigated in the presence of a group of
new “hybrid” structures, namely, N-substituted amides of salicylic acid whose structure contains an amide residue conjugated
with, or separated by a bridging fragment (three methylene groups) from, an N-phenolic substituent. The compounds also differ
in the degree of screening of the OH groups. The process was initiated by thermal decomposition of azobisisobutyronitrile
at 60°C (initiation rate of w
i
= 4.2 × 10−8 mol L−1 s−1) or by UV irradiation (γ = 313−365 nm, w
i
= 0.6 × 10−8 mol L−1 s−1). The compounds examined exhibit antiradical activity owing to the presence of the phenolic hydroxyl groups. N-substituted
salicylamides efficiently inhibit the overall methyl oleate oxidation process and are comparable in activity with dibunolum
and α-tocopherol or are superior to them. The structures in which the residues of salicylamide and sterically hindered phenol
are separated by the bridging fragment are particularly efficient. The advantages of the salicylamides absorbing at 300–365
nm manifest themselves in UV-initiated oxidation. The peroxidase activity of the N-substituted salicyl acid derivatives is
determined by the structure of the amide moiety. The compounds examined here are new, promising, effective antioxidants, whose
particular structural fragments act via different mechanisms in oxidation. 相似文献
16.
E. Yu. Pikalova V. G. Bamburov A. A. Murashkina A. D. Neuimin A. K. Demin S. V. Plaksin 《Russian Journal of Electrochemistry》2011,47(6):690-696
CeO2-based solid solutions with a fluorite structure are promising materials as electrolytes of medium-temperature electrochemical
devices: electrolytic cells, oxygen sensors, and solid oxide fuel cells. In this work, studies are presented of the effect
of the dopant cation radius and its concentration on the physico-chemical properties of the Ce1 − x
Ln
x
O2 − δ solid solutions (x = 0–0.20; Ln = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb) and also of multicomponent solid solutions of Ce1 − x
Ln
x/2Ln′
x/2O2 − δ (x = 0–0.20; Ln = Sm, La, Gd and Ln′ = Dy, Nd, Y) and Ce1 − x − y
Sm
x
M
y
O2 − δ (M = Ca, Sr, Ba) obtained using the solid-phase synthesis technique. Electric properties of the samples were studied in the
temperature range of 623–1173 K and in the oxygen partial pressure range of 0.01–10−22 MPa. The values of oxygen critical pressure ( pO2 * )\left( {p_{O_2 }^* } \right) are presented, at which the ionic and electron conductivity values are equal. The values were calculated on the basis of
experimental dependences at 1023 K at the assumption that the ionic conductivity value is determined only by the dopant concentration
and its effective ionic radius and is independent of the oxygen partial pressure. 相似文献
17.
Bahram Ghalami-Choobar Vahid Mahdavi Shadfar Pourpanah 《Journal of solution chemistry》2012,41(1):89-99
In this work mean activity coefficient measurements for KCl in the KCl + formamide + water system, using the potentiometric
method, are reported. The electromotive force measurements were performed on a galvanic cell of the type Ag | AgCl | KCl (m), formamide (w%), H2O (1−w)% | K-ISE, in solvent mixtures containing w=(0,10,20,30, and 40)% mass percent of formamide over ionic strengths ranging from 0.0010 to 3.9578 mol⋅kg−1. Modeling of the activity coefficients of this ternary system was based on an extended Debye–Hückel equation and the Pitzer
ion-interaction model. The resulting values of the mean activity coefficients, the osmotic coefficients and the excess Gibbs
energy, together with Pitzer ion-interaction parameters (β
(0), β
(1) and C
ϕ
) and Debye–Hückel parameters (a, c and d), are reported for the investigated system. 相似文献
18.
A polystyrene-based membrane of 7,8:16,17-dibenzo-6,9,15,18-tetraoxo-1,5,10,14-tetrathiacyclooctadeca-7,16-diene [Bz2Oxo4(18)dieneS4] was fabricated using sodium tetraphenylborate (NaTPB) and dioctyl phthalate (DOP) as anion excluder and plasticizing agent.
The best performance was obtained from the membrane with the composition ionophore [Bz2Oxo4(18)dieneS4]:polystyrene:DOP:NaTPB, 5:100:150:10 (w/w). The response of the electrode was linear over a wide range of concentration, 1.26×10–6–1.00×10–1 mol L−1 for silver ion with a Nernstian slope of 58.4±0.1 mV per decade and a detection limit of 1.0×10−6 mol L−1. The electrode was found to be chemically inert and of adequate stability with a response time of 10 s and could be used
for a period of 3 months without change of potential. It worked satisfactorily in mixtures containing up to 35% (v/v) non-aqueous content. The proposed membrane sensor had good selectivity for Ag+ over a wide variety of metal ions in the pH range 2.2–8.5. It was successfully used as an indicator electrode in potentiometric
titration of silver ion. The electrode was also useful for determination of Ag+ in waste from photographic films. 相似文献
19.
Callus induction and plant regeneration from different explants of Actinidia deliciosa 总被引:1,自引:0,他引:1
In this study, an efficient procedure was developed for callus induction and regeneration of kiwifruit (Actinidia deliciosa) using different organs of shoots developed under in vitro conditions. Effects of explants source and media (M1, 1.0 mg l−1 BA + 2.0 mg l−1 2,4-D–M2, 1.0 mg l−1 NAA + 2.0 mg l−1 2,4-D) on initiation of callus were examined in order to obtain callus for organogenesis. The best callus for plant regeneration
was obtained from leaf explants on Murashige and Skoog’s medium (MS) supplemented with M2. Formation of callus from leaf of kiwifruit (A. deliciosa) was cultured in MS medium containing different concentration of N6-benzylaminopurin (BA; 0.0, 1.0, 2.0, 4.0, 6.0, 8.0 mg l−1) for callus proliferation and plant regeneration. Although the first shoot formation was appeared in medium containing 6.0
and 8.0 mg l−1 BA, the best shoots formation was obtained in medium with 4.0 mg l−1 BA. 相似文献
20.
Ahmad Soleymanpour Bahram Garaili S. Masoud Nabavizadeh 《Monatshefte für Chemie / Chemical Monthly》2008,139(12):1439-1445
Three platinum(II) complexes were synthesized and studied to characterize their ability as an anion carrier in a PVC membrane electrode. The polymeric membrane electrodes (PME) and also coated glassy carbon electrodes (CGCE) prepared with
one of these complexes showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to ClO4
− ions over a wide concentration range from 1.5 × 10−6 to 2.7 × 10−1 M for PME and 5.0 × 10−7 to 1.9 × 10−1 M for CGCE with low detection limits (9.0 × 10−7 M for PME and 4.0 × 10−7 M for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly,
good selectivity toward ClO4
− relative to a variety of other common anions. The potentiometric response of the electrodes is independent of the pH of the test solution in the pH range 2.0–9.0. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine
samples.
Correspondence: Ahmad Soleymanpour, Department of Chemistry, Damghan Basic Science University, Damghan, Iran. 相似文献