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1.
| 1. | Thermodesorption measurements have shown the surface of aluminum-nickel-tungsten sulfide catalysts to be nonuniform with respect to cyclohexane, the nonuniformity being characterized by an exponential distribution, a step adsorption isotherm, and a logarithmic fall off of the desorption activation energy with increasing surface coverage. |
| 2. | The degree of cyclohexane coverage of the catalyst surface is increased by the presence of hydrogen, and the energy of adsorptional bonding is reduced. |
| 3. | Cyclohexane bonds to the catalyst surface more weakly than does benzene, and can be completely displaced from the surface by the latter. |
2.
L. F. Chertanova G. A. Marchenko A. A. Gazikasheva Yu. T. Struchkov V. F. Sopin L. N. Punegova A. S. Mukhametzyanov 《Russian Chemical Bulletin》1989,38(2):250-253
| 1. | The planar alkoxydiazinoxide fragments are shown to have the Z-configuration and be orthogonal to each other by an x-ray structure study of a series of alkoxydiazinoxides. |
| 2. | In the oxydiazinoxide fragments, p- conjugation occurs. |
| 3. | The molecules of the compounds in the crystals studied are joined by hydrogen bonds. |
3.
B. A. Arbuzov O. Éxsner A. P. Timosheva V. E. Kataev S. G. Vul'fson A. N. Vereshchagin 《Russian Chemical Bulletin》1976,25(6):1206-1212
| 1. | The dipole moments of the two kinds of C-O bonds in acetals and their analogs are not identical. |
| 2. | In formal molecules and the dimethylketal of acetone the C-O-C-O -C chains have gauche-gauche conformation, with the methyl groups lying on different sides of the O-C-O plane. |
| 3. | The dimethylketal of tetrachlorocyclopentadienone is represented by a mixture of trans-gauche and gauche-gauche conformers. |
4.
| 1. | In urethane crystals, infinite chains of hydrogen bonds organize the urethane molecules into layers with two principal types of packing: fir-tree and stacked. The stacked packing sometimes leads to the formation of a quasiskeletal structure. |
| 2. | The geometry of the hydrogen bonds is governed by the packing of neighboring molecules. |
| 3. | The frequency of the stretching vibration band of the NH group in IR spectra cannot be used to judge the geometry of hydrogen bonds in crystalline urethanes, since the geometry is governed not only by the H...O interaction of the hydrogen bond N-H...O=C, but also by the total energy of intermolecular interaction. |
5.
I. V. Anonimova N. A. Chadaeva L. K. Yuldasheva S. G. Vul'fson A. N. Vereshchagin B. A. Arbuzov 《Russian Chemical Bulletin》1976,25(12):2519-2524
| 1. | It has been shown that 2-bromo-l,3,2-dioxaarsenanes exist in chair conformation with axially oriented As-Br bonds. |
| 2. | Polarity and polarizability parameters have been found for the As-O and As-Br bonds in 2-bromo-l,3,2-dioxaarsenanes. |
| 3. | The so-called -effect is stronger in the O2AsBr group than in the O2AsCl group. |
6.
| 1. | The rate constant for the destruction of radical pairs decreases with increase in the distance between the traps of the H atom. |
| 2. | A mechanism was proposed for the destruction of radical pairs, according to which the main channel for hydrogen transfer during annealing does not coincide with the channel for phototransfer when the RP are formed. |
| 3. | Based on a formally kinetic analysis for a stepwise rate, distribution parameters based on the activation energies were found for the deuterated and undeuterated samples. A superficial estimate was made of the change in the activation energy when the distance between the unpaired electrons in the radical pairs is changed by one unit of length. |
7.
B. A. Arbuzov S. G. Vul'fson G. G. Butenko O. A. Samarina A. B. Teitel'baum A. N. Vereshchagin 《Russian Chemical Bulletin》1976,25(1):75-81
| 1. | The ellipsoids of polarizability of dimethylsulfone, sulfuryl chloride, and methanesulfonyl chloride were determined, and the nonadditivity of the parameters of the bonds in the sulfonyl chloride group was demonstrated. |
| 2. | Substituted methane sulfonyl chloride exist in gauche conformations. |
| 3. | In benzenesulfonyl chloride and a series of its para-substituted derivatives, the aryls are situated in the C-S-Cl plane; the para-nitro group induces a 35° rotation. |
8.
Rif. R. Shagidullin A. V. Chernova A. Kh. Plyamovatyi R. R. Shagidullin 《Russian Chemical Bulletin》1989,38(3):638-641
| 1. | The IR spectra of a solution of mercaptoethanol in CCl4 and in gas-phase mercaptoethanol have XH bands for free OH and SH groups and OH...S and SH...O groups in intramolecular hydrogen bonds. This indicates a conformational multiplicity of the ME molecules. |
| 2. | A molecular mechanics calculation indicates the possibility of conformational multiplicity for mercaptoethanol. The energy of the intramolecular OH...S hydrogen bond was evaluated. |
9.
| 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. |
10.
S. P. Freidman N. I. Medvedeva G. S. Nazarova V. A. Gubanov 《Journal of Structural Chemistry》1991,32(5):631-636
| 1. | The Al–O and P–O chemical bonds in variscite are mainly covalent in nature. The degree of covalency of the P–Ob chemical bond is substantially greater than that of Al–Ob. |
| 2. | The presence of nonequivalent bonds of oxygen atoms in water molecules in variscite (H–OW–H) and bonds of bridge oxygen atoms (P–Ob–Al) leads to splitting of the 02s and 02p states of the OW and Ob atoms amounting to 7 eV. |
| 3. | The strength of the Al–OW bond is considerably lower than that of the Al–Ob bond. |
| 4. | The H11, H21, and H22 hydrogen atoms form hydrogen bonds with the bridge oxygen atoms, but H12 does not participate in hydrogen bonding. |
| 5. | The results from cluster calculations of the electronic structure of variscite provide a basis for interpreting the experimental x-ray photoelectron spectrum and for determining the influence of structural molecules of water on the XPS line shape and structure. |
11.
A. A. Glazkov A. V. Ignatenko S. P. Krukovskii V. A. Ponomarenko 《Russian Chemical Bulletin》1976,25(4):896-898
| 1. | The transformations of perfluoromethylvinyl and perfluoromethoxypropylvinyl ethers in the presence of ionic fluorides in aprotonic solutions have been studied. |
| 2. | In the absence of perfluoroolefins, prefluorovinyl ethers do not form dimers with unsaturated bonds, but are transformed into perfluoroetheroketones as the result of a series of successive reactions. |
12.
| 1. | For dyes the steric hindrance that is ereated when several hydrogen atoms are replaced by fluorine leads to a decrease of 1.5-2 times in the activation energy for the relaxation of the photoisomers and a decrease in the life span of the photoisomers by 3–4 orders of magnitude when compared with the unhindered photoisomers of the dyes. Despite the great steric hindrance, the radiationless degradation of the energy goes for the dyes by the path of cis—trans isomerization. |
| 2. | Isomerization from the triplet states of the dyes causes a rapid deactivation of the triplets in the ground state of the photoisomer. |
| 3. | Due to the high coefficient of converting the radiation and the photochemical stabilitys, 3,3'-diethyl-9-fluor othiacarbocyanine can be used successfully as an active medium for lasers. |
13.
Yu. V. Kuznetsov L. G. Stolyarova V. P. Lezina L. D. Smirnov 《Russian Chemical Bulletin》1989,38(7):1494-1500
| 1. | New halogen derivatives of 1-ethyl-2-methyl-, 2-methyl- and 5-hydroxybenzimidazole were obtained. |
| 2. | A method for the chlorination of aromatic compounds by an alcoholic solution of hydrogen chloride in the presence of hydrogen peroxide was proposed, which enables carrying out the reaction with a high yield. |
| 3. | The reactivity of the series of 5(6)-hydroxybenzimidazole derivatives during the electrophilic substitution (halogenation) was shown to be as follows: 1-ethyl-2-methyl-5-hydroxybenzimidazole >5(6)-hydroxybenzimidazole 2-methyl-5-hydroxybenzimidazole. |
14.
| 1. | It was found that trivalent rhenium chloride has a high activity in the hydrogenation of the C=C bonds in cyclohexene, the pyridine ring, and thiophene at 200–270°, a hydrogen pressure of 130–140 atm, and a reaction time of 3 h. |
| 2. | Rhenium(III) chloride has a higher activity than rhenium heptasulfide in reducing the C=C bond in cyclohexane and the pyridine ring |
15.
| 1. | A new type of sorbents, containing SH groups, was obtained by the modification of aminooxy adsorbents. |
| 2. | The obtained sorbents were used for the covalent immobilization of biologically active compounds with the formation of C-S, C-Hg-S, and S-S bonds. |
16.
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. |
17.
K. B. Petrushenko A. I. Vokin V. K. Turchaninov S. E. Korostova 《Russian Chemical Bulletin》1988,37(1):32-39
| 1. | The acid properties of short-lived radicals from the pyrrole, indole, benzazole, and benzoquinone series were studied by nanosecond laser spectroscopy in acetonitrile. |
| 2. | The linear dependence of the change in the standard free energy of formation of neutral radicals as a result of transfer of an H atom from the heterocyclic molecules to the quinone molecules and a change in the standard free energy of electron transfer in these systems was demonstrated. |
| 3. | The role of intermediate states with electron transfer in the process of photoinduced cleavage of the hydrogen atom was investigated. It was found that the efficiency of formation of products of atom transfer is determined by the acid-base properties of the components of the radical ion pairs (exiplexes). |
18.
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%). |
19.
S. F. Vasilevskii A. N. Sinyakov M. S. Shvartsberg I. L. Kotlyarevskii 《Russian Chemical Bulletin》1976,25(10):2134-2138
| 1. | Depending on the conditions, the reaction of methyl aryl ketones with phosphorus pentachloride leads to products from substitution of the carbonyl oxygen by chlorine, αβ-dichlorovinylarenes, or compounds with higher degrees of chlorination. |
| 2. | By eliminating a molecule of hydrogen chloride under the influence of an equimolar amount of sodium amide in ammonia, substituted, α,β-dichloroethylenes give high yields of the respective 2-chloroacetylene. |
| 3. | The synthesis of a series of ethynyl- and β-chloroethynylpyrazoles from methylpyrazolyl ketones was realized. |
20.
| 1. | Increased pressure results in an increase in the proportion of the cis isomer in adducts formed by diene condensation of trans-1-methoxy- and 1-ethoxy-1,3-butadiene with methyl, ethyl, and n-butyl glyoxylate and acetaldehyde. |
| 2. | The transition state in these reactions structurally resembles the parallel-plane model of the prereaction complex rather than adduct. |