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1.
| 1. | The potential energy of the interaction of one water molecule with the walls of a micropore E(Zc) as a function of the distance to its lower surface has one or two minima, determined by the half-width of the micropore d. |
| 2. | The height of the barrier U between the minima of E(Zc) and distance R between these minima for a given model potential of the water-carbon interaction increase linearly with an increase in the slit half-width. The values of the coefficients of these linear dependences were obtained empirically. |
| 3. | The dependence of the transverse diffusion coefficient on d for one molecule of water has one distinct maximum at d 0.41 nm. For this micropore, the height of the barrier gDU between the minima of E(Zc) is kT. For a cluster of six water molecules, there is also a maximum, but at d 0.35 nm, which is due to the formation of hydrogen bonds between the molecules of water. |
| 4. | Note that with a micropore half-width of d > 0.375 nm, for a cluster of 19 molecules of water, the number of hydrogen bonds is 18 per cluster and increases monotonically with an increase in d from 0.36 to 0.46 nm. In the 0.47–0.5 nm region, the average number of hydrogen bonds is almost independent of d. |
| 5. | When d < 0.42="" nm,="" the="" hydrogen="" bonds="" prevents="" the="" optimum="" orientation="" of="" the="" molecules="" with="" respect="" to="" the="" nearest="" surface="" of="" the="" pore="" and="" when="" d=""> 0.425 nm, they favor localization of the water near the walls of the micropore. |
2.
A. M. Voloshchuk M. M. Dubinin T. A. Moskovskaya A. O. Larionova L. A. Shilkova 《Russian Chemical Bulletin》1988,37(10):1979-1983
| 1. | The adsorption isotherms of N2 at 77 K on the surface of carbonaceous adsorbents in the region of low relative pressures are satisfactorily described by the Dubinin-Radushkevich (DR) equation. However, the a0 parameter of the DR equation is not related to the monolayer capacity, and for samples with the most homogeneous surface the quantity a0 substantially exceeds the BET monolayer capacity. |
| 2. | The adsorption isotherms calculated per unit surface area of adsorbent can be grouped in terms of the E0 value of the DR equation; this can be regarded as a measure of the degree of energetic heterogeneity of the samples. |
| 3. | For samples with E0 < 15.5="" kj/mole,="" the="" specific="" surface="" areas="" calculated="" by="" the="" bet="" method="" and="" by="" the=""> and methods are similar. |
| 4. | The samples of carbonaceous adsorbents with E0 > 15.5 kJ/mole are characterized by surface heterogeneity associated with the presence of micropores. |
3.
| 1. | The authors have studied the formation of electron and hole paramagnetic centers in gamma-irradiated magnesium hydroxide and oxide with various degrees of dehydration. |
| 2. | Rise in the temperature of preliminary heat treatment of the magnesium oxide causes an increase in the radiation-chemical yield of FS + centers and a decrease in that of V su – centers. |
| 3. | The thermal stability of paramagnetic centers in magnesium oxide increases as the hydroxyl group content decreases. |
4.
| 1. | Following the CNDO/2 approximation to the SCF MO LCAO method, electronic parameters have been calculated for the molecules and ions of various nitro compounds. |
| 2. | Calculated values of the dipole moment and enthalpy of atomization proved to be in satisfactory agreement with the experimentally determined values, the maximum deviation between them amounting to 1.4% for the aromatic systems. |
| 3. | The nitro compound parameters most sensitive to change in the intramolecular interaction are the C-N bond energy and the charges on the carbon and halide atoms. |
5.
| 1. | Indium atoms have been obtained in aqueous solutions of univalent indium by pulse radiolysis. |
| 2. | In0 reacts with In+ to form the dimer In 2 + . |
| 3. | The optical characteristics of these particles, the rate constants for their formation and loss, as well as the oxidation-reduction potentials have been determined. |
6.
T. E. Kron V. S. Lopatina L. N. Morozova S. A. Lebedev L. S. Isaeva D. N. Kravtsov é. S. Petrov 《Russian Chemical Bulletin》1989,38(4):703-707
| 1. | The complexes ArNiXL2 and HNiXL2 (X is halide, L is tertiary phosphine) in the presence of zinc catalyze the condensation of bromobenzene with styrene (stilbene formation). |
| 2. | The yield of stilbene and 1,3-diphenylbutene, the dimerization product of styrene, in the presence of pyridine is lowered according to the substitution of phenyl groups on the phosphorus ligand L by alkyl (ethyl, cyclohexyl) groups. |
| 3. | Change of triphenylphosphine to phenylethylphosphines and tricyclohexylphosphine in the hydride complex HNi(X)(PR3)2, the catalytic activity of which falls in the order X=Cl–Br–>I–, favors the dimerization of styrene in the absence of pyridine. |
7.
A. I. Kokorin L. S. Bogach A. B. Shapiro É. G. Rozantsev 《Russian Chemical Bulletin》1976,25(9):1874-1878
| 1. | Nitroxyl biradicals of the triazine, N,N-bis(triazinyl)ethylenediamine, N,N-bis(triazinyl)piperazine, and s-nitropyrimidine series have been prepared. |
| 2. | The ESR spectra of liquid and frozen solutions of these biradicals have been obtained and N. - O group separations calculated. |
| 3. | Toluene solutions of (II), (V), (VI), and (X) biradicals contain at least four different conformations, each with its own value of the exchange integral. |
| 4. | In one of the biradical (V) conformations, spin interaction exchange is through the chain of atoms linking the N.-O fragments. |
8.
K. B. Yatsimirskii M. I. Kabachnik T. Ya. Medved' N. P. Nesterova É. I. Sinyavskaya L. V. Tsymbal F. I. Bel'skii 《Russian Chemical Bulletin》1988,37(1):44-49
| 1. | Stability constants for alkali metal complexes of composition [ML]+ and a copper complex [CuLCl]+, which are formed via treatment of alkali metal 2,4-dinitrophenolate or copper chloride with a series of carbamoyl phosphine oxide derivatives, have been determined in anhydrous solutions. |
| 2. | The most stable complexes are formed by ligands containing an aryl substituent attached to the phosphorus atom. |
9.
| 1. | Potentiometric titration in nitromethane at 25°C has been used to determine dissociation constants for 16 mono-substituted benzoic acids. |
| 2. | Brönsted and Hammett equations have been set up for the compound series under study here. |
| 3. | The data of the literature have been used to evaluate the nitromethane autoprotolysis constant, pKS24. |
| 4. | The relative differentiating action of nitromethane with respect to other solvents has been evaluated from the slopes of the Brönsted and Hammett plots and the values of the autoprotolysis constant. The differentiating action of nitromethane with respect to acids is greater than that of acids with respect to alcohols and acetone, but less than that of DMSO, acetonitrile, and DMF. |
| 5. | Study has been made of the dissociation of the aminobenzoic acids in nitromethane. Solutions of p-aminobenzoic acid are free of zwitterions, while solutions of the m-aminobenzoic acid contain these ions to the extent of 50%. |
10.
N. D. Chkanikov V. L. Vershinin M. V. Galakhov A. F. Kolomiets A. V. Fokin 《Russian Chemical Bulletin》1989,38(1):113-119
| 1. | Nonsterically hindered primary arylamines react with hexafluoroacetone benzenesulfonyl- and trifluoroacetylimines to give stable gem-diamino compounds. |
| 2. | The presence of substituents at the nitrogen of the arylamine destabilizes these gem-diamino compounds, with the formation of C2- and C4-alkylation products. With hexafluoroacetone trifluoroacetylimine, C2-alkylation is accompanied by heterocyclization to give 1-substituted 2,4,4-tris(trifluoroacetyl)-1,4-dihydroquinazolines. |
| 3. | N,N-Dialkylanilines are regioselectively alkylated at C4. |
11.
G. A. Artamkina A. Yu. Mil'chenko I. P. Beletskaya O. A. Reutov 《Russian Chemical Bulletin》1988,37(12):2550-2556
| 1. | The kinetics of reactions of alkali metal salts of 9-carbomethoxy- and 9-cyanofluorene with para-nitrofluorobenzene and of Me3SnM with pentafluoropyridine have been studied. |
| 2. | In the case of carbanions the free anions are more reactive, while in the case of Me3SnM the corresponding tight (contact) ion pairs are more reactive. |
| 3. | The effect of the leaving group (on reactivity) was investigated using the reactions of pentafluorochlorobenzene with the K salts of 9-carbomethoxyfluorene and cyclopentadienylirondicarbonyl anions as examples. |
| 4. | The reaction mechanism has been shown to depend on the nature of the nucleophile. |
12.
| 1. | The direct electrochemical synthesis of various complex fluorides of aluminum, gallium, and indium has been carried out by means of the anodic dissolution of the metal in the presence of a tetraalkylammonium fluoride polyhydrofluoride. |
| 2. | The ability of each metal to form fluorine-containing ammonium complexes under the conditions of an electrochemical reaction decreases upon the transition from Al to Tl. |
13.
V. M. Belikov Yu. N. Belokon' V. A. Karginov N. S. Martinkova M. B. Saporovskaya 《Russian Chemical Bulletin》1976,25(6):1233-1238
| 1. | The formation of protonated and free Schiff's bases from S-alanine and salicylaldehyde was studied quantitatively by the PMR method in the interval of pD 9.0–12.0. |
| 2. | The rate constants of the racemization of S-alanine and its Schiffs base with salicylaldehyde protonated at the nitrogen were determined, and they were compared with the analogous constants for N-salicyl-idene-S-alaninate complexes of Cr(III), Rh(III), and Co(III) and the Schiffs base from pyridoxal and S-alanine. |
| 3. | The basic role of the metal in the model reactions consists of increasing the concentration of reactive particles in solution as a result of coordination of the Schiffs base with the metal ion. |
14.
| 1. | Replacing Na+ ions by Ca2+in zeolites leads to a significant shift of the region in which thermally stimulated polarographic [TSD] current peaks appear toward higher temperatures. |
| 2. | Reducing the cation content in zeolites leads to a decrease in the intensity of TSD currents. |
| 3. | The data obtained-can be explained by the differences in the distributions of the cations between different crystallographic positions in the zeolite lattices. |
15.
B. A. Glazun R. N. Kurnosova M. M. Dubinin I. V. Zhilenkov S. S. Levchenko 《Russian Chemical Bulletin》1976,25(1):8-11
| 1. | In NaA zeolite a homocharge is formed by charges deposited on the surface of the zeolite from the gas gap between the electrode and the specimen. |
| 2. | The existence of thermoelectret effects has been found in the systems NaA-zeolite -air, NaA-helium, NaA-nitrogen, and NaA-oxygen. |
| 3. | The thermoelectret effects are caused by both the accumulation of charges in the specimen and the adsorption of molecules in the electric field. |
| 4. | A low mobility has been noted for adsorbed molecules in the electret state of the system. |
16.
L. S. Isaeva G. I. Drogunova A. S. Peregudov D. N. Kravtsov 《Russian Chemical Bulletin》1988,37(1):153-157
| 1. | New cationic o-tolyl and o-fluorophenyl complexes of Ni containing Ph3P, MeCN, or THF ligands have been synthesized. |
| 2. | Reaction of these compounds with potassium carboxylates gave the novel o-tolyl and o-fluorophenylbis(triphenylphosphinyl)nickel carboxylates. |
| 3. | According to19F NMR data o-tolylbis(triphenylphosphinyl)nickel p-fluorobetizoate contained a highly polarized Ni-O bond. |
17.
V. A. Afanas'ev T. G. Vaistub L. S. Medoks G. N. Nesterenko T. G. Panina B. G. Rogachev 《Russian Chemical Bulletin》1989,38(4):861-862
| 1. | An electrochemical system was proposed with a soluble metal anode for the exhaustive reduction dehalogenation of 7,7-dichloronorcarane, which permits an enhanced yield of norcarane both relative to current and substrate. |
| 2. | The efficiency of the metal anodes used falls in the series Al>Sn>Fe. |
18.
E. Franceschi A. Del Lucchese D. Palazzi G. Rossi 《Journal of Thermal Analysis and Calorimetry》1997,49(3):1593-1600
Prehistoric metal findings from Liguria are numerous, however, even though there were many metalliferous mines, the metal-working sites have not yet been ascertained.This work discusses results on some metal objects from different archaeological sites in Liguria.The objects examined were: 1) two melting drops 2) an axe, and 3) a knife. The physico-chemical investigation techniques employed were:
This work was supported by the Italian C. N. R., Comitato Nazionale per la Scienza e la Tecnologia dei Beni Culturali, Progetto Strategico Beni Culturali.Thanks are due to the Directress of the Calvet Museum, Mrs. Jadwiga Krzepowska, for kind permission to observe and study the fusion mould.The authors thank Mr. Claudio Uliana for the measurements carried out on the S.E.M. apparatus. 相似文献
| – | X-ray diffraction, |
| – | radiography, |
| – | microdrawing method, followed by optical and electron scanning microscopy observations, |
| – | differential thermal and thermogravimetric analyses to characterize the clay core found inside a socketed knife. |
19.
The energy metabolism of a mammalian cell line grown in vitro was analyzed by substrate consumption rates and metabolic flux
measurements. The data allowed the determination of the relative importance of the pathways of glucose and glutamine metabolism
to the energy requirements of the cell. Changes in the substrate concentrations during culture contributed to the changing
catalytic activities of key enzymes, which were determined.
相似文献
| 1. | A murine B-lymphocyte hybridoma (PQXB1/2) was grown in batch culture to a maximum cell density of 1–2×106 cells/mL in 3–4 d. The intracellular protein content showed a maximum value during the exponential growth phase of 0.55 mg/106 cells. Glutamine was completely depleted, but glucose only partially depleted to 50% of its original concentration when the cells reached a stationary phase following exponential growth. |
| 2. | The specific rates of glutamine and glucose utilization varied during culture and showed maximal values at the midexponential phase of 2.4-nmol/min/106 cells and 4.3 nmol/min/106 cells, respectively. |
| 3. | A high proportion of glucose (96%) was metabolized by glycolysis, but only limited amounts by the pentose phosphate pathway (3.3%) and TCA cycle (0.21%). |
| 4. | The maximum catalytic activity of hexolinase approximates to the measured flux of glycolysis and is suggested as a rate-limiting step. In the stationary phase, the hexokinase activity reduced to 11% of its original value and may explain the reduced glucose utilization at this stage. |
| 5. | The maximal activities of two TCA cycle enzymes were well above the measured metabolic flux and are unlikely to pose regulatory barriers. However, the activity of pyruvate dehydrogenase was undetectable by spectrophotometric assay and explains the low level of flux of glycolytic metabolites into the TCA cycle. |
| 6. | A significant proportion of the glutamine (36%) utilized by the cells was completely oxidized to CO2. |
| 7. | The measured rate of glutamine transport into the cells approximated to the metabolic flux and is suggested as a rate-limiting step. |
| 8. | Glutamine metabolism is likely to occur via glutaminase and amino transaminase, which have significantly higher activities than glutamate dehydrogenase. |
| 9. | The calculated potential ATP production suggests that, overall, glutamine is the major contributor of cellular energy. However, at the midexponential phase, the energy contribution from the catabolism of the two substrates was finely balanced—glutamine (55%) and glucose (45%). |
20.
| 1. | The authors suggest a model to explain the axial symmetry of the hole center V– in magnesium oxide. |
| 2. | Using the model they consider the possible alternatives for localization of the hydroxyl groups of the hole center. |
| 3. | In analytic form, they express the values of the g factors for the V– center in terms of the parameters of the method of molecular orbits. The experimental values of the g factors can be explained if we assume localization of one or two hydroxyl groups in the first or second layer from the O– radical ion in the MgO lattice. |