首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 250 毫秒
1.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

2.
The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.  相似文献   

3.
Heats of formation of solid, liquid, and gaseous nitroalkanes have been shown mostly to obey group additivity. Group values have been obtained for carbon atoms attached to one, two, and three nitro groups. The heat of formation of 1,1,1,3,5,5,5,-heptanitropentane, either solid or liquid, cannot be fitted to the scheme, even allowing for gauche effects. The differences between observed and estimated values for 1,1,1-fluorodinitroalkanes and 1,2-dinitroethane are larger than expected and should be further investigated. Activation energies have been calculated for decomposition by five-center elimination of HONO from mononitro- and dinitroalkanes using thermochemistry and estimated activation energies for the reverse reactions. The key data for these estimates were previously reported activation energies for the decomposition of nitroethane and 1,2-dinitropropane. The calculations also gave values for the heats of formation (in kcal/mole) of nitroethylene 12.4, and 1-nitropropylene 5.6, and 2-nitropropylene 1.6. Activation energies were calculated for the competing unimolecular reaction, C? N bond fission, from thermochemistry and previously reported activation energies for the decomposition of 1,1- and 2,2-dinitropropane. Comparison of Arrhenius parameters for the two competing processes, namely, HONO and C? N bond fission, shows that, for the geminate dinitroethanes and dinitropropanes, C? N bond fission is faster about 370°K and, for the mononitroalkanes and for all the mononitroalkanes and dinitroalkanes, C? N bond fission is faster above 770°K.  相似文献   

4.
Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.  相似文献   

5.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

6.
Catalytic thermal destruction of ethylenediaminetetraacetic acid and its complexes with nickel, iron, and cobalt in nitrate solutions on carbon materials (activated unwoven material, sibunite, and BAU–A activated carbon) was studied. The activation energies of thermal destruction were calculated.  相似文献   

7.
Sorbents based on porous and nonporous varieties of silica containing chemisorbed primary amines, alcohols, amino-alcohols, amide groups, and phenyl radicals with different types of substituents in the surface layer have been synthesized. It has been established that, depending on the nature of the modifying layer, electrostatic and hydrophobic interactions make the principal contribution to the adsorption of proteins. The supports obtained may be used for the immobilization and Chromatographic separation of biopolymers.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 2, pp. 237–241, March–April, 1987.  相似文献   

8.
栽培草莓品种果实香气特性研究   总被引:15,自引:0,他引:15  
通过对4个不同栽培草莓(Fragaria ananassa Duch.)品种果实糖和氨基酸测定及香气的GC-MS分析,结果表明:不同品种间氨基酸和糖含量不同,氨基酸含量由高到低依次为丰香、瓦尔达、哈达和全明星;哈达、丰香、全明星和瓦尔达4个品种果实分别检测出39、46、37和44种香气成分,各占总峰面积98.52%、99.15%、98.77%和95.4l%,检测成分的多少与氨基酸总量显著正相关,相关系数为0.967;哈达有5种独有的成分,丰香有9种独有的成分,全明星有3种独有的成分,瓦尔达有2种独有的成分,4个品种共有的成分有19种。  相似文献   

9.
A mechanism of photocatalytic synthesis of chlorohydrins from olefins and peroxo complexes of titanium (IV) is proposed. It consists of formation of radical-containing complexes, their reactions with olefins, and decomposition of the α-oxides obtained by hydrogen chlorides. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prosp. Nauki, 252039 Kiev, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 17–21, January–February, 1997.  相似文献   

10.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

11.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

12.
Conclusions Aconitine, songorine, and songoramine have been isolated fromAconitum karakolicum. The structure of songoramine has been established on the basis of chemical and spectral characteristics. A scheme for the fragmentation of songorine and its derivatives has been proposed.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 1, pp. 101–107, 1970  相似文献   

13.
论述了单元教学是落实化学新课程三维目标的基本教学过程,同时对教学单元的含义、教学单元的选择与建构、化学单元教学设计及其意义进行了阐述。  相似文献   

14.
The quantum-chemical method B3LYP/6-311G(d,p) was used to calculate structural parameters of four conformers of 9,10-dihydroxyanthracene, two conformers of 9-hydroxyanthrone, and the corresponding anions, dianion, and radical anion. The energy of 9,10-dihydroxyanthracene in a gas phase is higher and in aqueous solution lower than the energy of 9-hydroxyanthrone. The dianion can exist exclusively in a polarizable medium.  相似文献   

15.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

16.
The complex of high-molecular-weight substances of the cell walls of the grape has been studied. It has been shown that the complex contains polysaccharides, proteins, and phenolic substances presumably linked through O-glycosidic bonds."Magarach" Scientific-Research Institute of Wine-Making and Wine-Growing, Yalta, M. V. Frunze Simferopol' State University, Khimiya Prirodnykh Soedinenii, No. 5, pp. 564–567, September–October, 1984.  相似文献   

17.
The thermal properties of the anthranilates of the alkali metals Li, Na, K, Rb and Cs were studied. Thermal, chemical and X-ray analyses and infrared spectroscopy were used to determine the reactions of decomposition of these compounds. The thermal properties of the anthranilates of the alkali metals were compared with those of other metals.This work was done within Project 01.17: New Methods in Analytical Chemistry and Their Application in the National Economy.  相似文献   

18.
The effect of triplet sensitizers, benzophenone and anthraquinone and metal acetylacetonates [Co(II, III), Cu, Sn, and Ni] on the photodegradation of polyurethane was examined. Ultravioletvisible (UV-V) absorption spectra, gel formation, and luminescence emission of the polymer before and after irradiation were measured. Changes in UV-V absorption of the polymer and the formation of an insoluble fraction in the polymer were accelerated in the presence of the triplet sensitizers, and (Co(II, III)), Cu, and Sn acetylacetonates. Unirradiated polyurethane was excited by irradiation at 290 and 346 nm, and emitted light at 310 and 420 nm. After 1/2 hr irradiation emission of luminescence was observed at 430 nm, excitation at 290 and 346 nm; after 2hr irradiation at 530 nm, excitation at 420 nm was observed. The results suggest that photodegradation of the polyurethane proceeds via excited triplet states forming excimer between the polymers at the initial stage and exciplexes between the polymer and degradation products or intermediates after a certain irradiation.  相似文献   

19.
The tendency of anions of sulphophthaleine dyes to heteroassociation was studied in aqueous solutions of phenol red, bromophenol blue, bromocresol green, bromocresol purple, and bromothymol blue. It was spectrophotometrically determined that single-(Han) and double-charged anions (An2−) of sul-phophthaleines can form stable heteroassociates of composition Ct+ · HAn and (Ct+)2 · An2− with cations (Ct+) of polymethine dyes, pinacyanol, and quinaldine red. The values of enthalpy formation of ions of dyes and heteroassociates were calculated using semi-empirical methods, then correlated with experimentally determined values of equilibrium association constants.  相似文献   

20.
Original methods of photochemical preparation of stable mono- (Cu, Ag, Au, Ni, Pd, Pt) and bimetallic nanoparticles in the form of optically transparent compact films on quartz surface and of volume dispersions in porous inorganic (silica glasses) and organic (MF-4SK fluorocarbon) materials, solid polymers (polyvinyl alcohol, polyethylene glycol, gelatin, latexes), and in liquid media (glycerol) are reviewed. The results of studies of spectral and structural characteristics of nanophase films under various experimental conditions are presented. Experimental mechanistic models and ways of controlling disperse composition of metal colloids, which can be used for photochemical synthesis of nanophase systems, are proposed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号