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 62 毫秒
1.
The volatile mono-and sesquiterpenes obtained from the needles and resin of Pinus armandi, P. tabulaeformis, and P. bungeana growing in the Qinling, Taibai, and Huanglong Mountain forest ecosystem were analyzed by means of GC-MS. Forty-eight constituents were identified, and α-pinene, β-pinene, 1R-α-pinene, β-caryophyllene, cadindiene, α-caryophyllene, D-limonene, and 1S-β-pinene were the major components of the mono-and sesquiterpenes in the needles and resin. The components of the volatile mono-and sesquiterpenes from the needles and resin at Qinling, Taibai, and Huanglong Mountains had remarkable differences in three pine species, whereas the monopertene content such as α-pinene, β-pinene, D-limonene, and camphene were mostly changed in the growing stage. The intraspecies variation in the different ecosystems can be attributed to the species’ geography and genetic variation, and even the adaptation of the pine species to different ecological environments. Moreover, monoterpenes and sesquiterpenes can be induced by the attack of bark beetles, of which the α-pinene, β-pinene, 1R-α-pinene, 1S-α-pinene, b-myrecene, and β-caryophyllene contents had positive relations with the attacking Dendroctonus armandi and D. valens. Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 430–433, September–October, 2006.  相似文献   

2.
 A simple and quick method of durable samples preparation by the thin layer method through direct digesting of the analysed material on the substrate has been presented. Four- and three-component mono- and polycrystals have been analysed. Standards have been used in calibration containing: Cr, Co, Ni, Cu, Zn, Ga, Se, Sb, Yb. To improve the correlation between the concentration and the fluorescent radiation models of mathematical corrections have additionally been used: multiple linear regression, Lucas-Tooth-Pyne model (L. T. P.) and de Jongh model (d. J.). Statistical parameters: detection limits for 0.5 mg samples: Cr–0.041%, Co–0.034%, Ni–0.042%, Cu–0.053%, Zn–0.054%, Ga–0.057%, Se–0.057%, Sb–0.113%, Yb–0.077%. Correlation coefficients: simple regression 0.9946–0.9997, multiple regression 0.9974–1.0000, L. T. P. 0.9993–1.0000, d. J. 0.9995–1.0000. Received August, 1, 1998. Revision March 25, 1999.  相似文献   

3.
In this review, a summary of our published results, completed with new unpublished data are considered together with some of other authors’ publications, making an attempt to reveal the mechanism of the third element co-deposition in electroless Ni–P plating and to define its influence on the ternary coatings’ properties. A model explaining the triple role of Cu added to the solution for electroless (EL) Ni–P plating is described: as a stabilizer [Cu(I)]; as an accelerator; and as a stability-affecting agent, forming a dispersed solid phase in the solution. The disproportionation reaction of Cu(I) has been taken into account. A planned experiment was performed using full-effect factorial design with two levels of three process variables, and the response surfaces were constructed. The interaction between the factors was revealed. The results are in harmony with the aforementioned model. In low-tin Ni–Sn–P coatings, the alloy components are uniformly distributed both on the surface and through the thickness. In contrast, high-tin coatings exhibit three-dimensional areas enriched in Sn and impoverished in Ni and P. As the reason for their formation, the disproportionation reaction of Sn(II) is suggested, supposed to be locally predominant over the hypophosphite oxidation. EL deposition of pure Sn onto Ni–Sn–P substrates is shown. The inclusion of Cu or Sn in EL Ni–P increases the thermal stability of amorphous state, ensures the preservation of a paramagnetic behavior and improves the corrosion resistance. Dedicated to the 70th birthday of Professor A. Vaskelis.  相似文献   

4.
The chemical compositions and antimicrobial activities of the essential oils from two Turkish endemic species, Prangos platychlaena and P. uechtritzii, were investigated. Hydrodistillation was used to isolate the essential oils, and the chemical analyses were performed by GC and GC-MS. The antimicrobial activity was tested by the microdilution technique against Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Candida albicans, C. krusei, and C. tropicalis. δ-3-Carene (3.39%) and p-cymene (3.38%) were identified as major components in P. platychlaena, and α-pinene (40.82%), nonene (17.03%), β-phellandrene (11.14%), δ-3-carene (7.39%), and p-cymene (4.90%) in P. uechtritzii. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 139–140, March–April, 2006.  相似文献   

5.
6.
A series of calcium silicate hydrate (C–S–H)-polymer nanocomposite (C–S–HPN) materials were prepared by incorporating poly(acrylic acid) (PAA) into the inorganic layers of C–S–H during precipitation of quasicrystalline C–S–H from aqueous solution. The as-synthesized C–S–HPN materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The XRD analysis of C–S–HPN materials suggest the intermediate organizations presenting intercalation of PAA within C–S–H and exfoliation of C–S–H. The SEM micrographs of C–S–H, PAA and C–S–HPN materials with different PAA contents exhibit the significant differences in their morphologies. The effect of the material’s composition on the thermal stability of a series of C–S–HPN materials along with PAA and C–S–H were studied by TG, DTA and DSC. Three significant decomposition temperature ranges were observed on the TG curves of all C–S–HPN materials.  相似文献   

7.
Data for 1966–2004 on methods for the construction of tetracyclic systems in which an isoindole ring is condensed with quinoline and isoquinoline fragments on the [1,2] side are reviewed. Methods and conditions for the synthesis of isoindoloquinolines and isoindoloisoquinolines are examined. Examples of the synthesis of physiologically active natural alkaloids possessing the structure of these condensed isoindoles are presented. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1123–1157, August, 2006.  相似文献   

8.
Three new alkaloids have been isolated from the epigeal part ofNitraria komarovii — peganine N-oxide, N-allylschoberine, and dehydronitramidine. Their structures have been determined on the basis of chemical transformations and spectral results. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 780–783, November–December, 1994.  相似文献   

9.
Data on methods for the construction of tetracyclic systems in which an isoindole ring is condensed with benzazepines and benzazocines on the [1,2] side are reviewed. The reaction conditions and approaches leading to isoindolobenzazepines and isoindolobenzazocines are discussed. Examples of the synthesis of physiologically active natural alkaloids with the structure of the above-mentioned condensed isoindoles are presented. Data for 1959–2004 are included. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 963–994, July, 2006.  相似文献   

10.
Graphite particles were coated with Ni–P by electroless deposition using a conventional bath consisting of a nickel salt and hypophosphite. After 15 min of electroless deposition, the graphite particles were covered with 10 wt% nickel and 0.7–1.0 wt% phosphorus as analysed by wet chemical method. Surface morphology was studied by scanning electron microscopy (SEM). Electrochemical characterisation for the catalytic activity was done by cyclic voltammetry. Pure Ni powder and electroless Ni–P coated on graphite were used as catalysts for the electro-oxidation of dextrose (1.8 × 10−3 to 4.5 × 10−3 M) in 0.1 M KOH solution. Comparative studies revealed that electroless Ni–P coated on graphite particles acted as a better catalyst than pure Ni powder for catalytic reaction.  相似文献   

11.
The effect of age on chemical element contents in intact prostate of 64 apparently healthy 13–60 years old men was investigated by neutron activation analysis with high resolution spectrometry of short-lived radionuclides. Mean values (M ± SΕΜ) for content (mg/kg, dry weight basis) of chemical elements were: Br–31.6 ± 3.2, Ca–2150 ± 160, Cl–12670 ± 675, K–12010 ± 400, Mg–1150 ± 75, Mn–1.56 ± 0.09, and Na–10520 ± 340, respectively. A tendency of age-related increase in Ca content and decrease in Mn content was observed.  相似文献   

12.
Condensation of bis(hydroxymethyl)mesityl-and bis(hydroxymethyl)phenylphosphines with N,N′-disubstituted bis(4-aminophenyl)methanes and bis(4-amino-3-carboxyphenyl)methane occurred as covalent self-assembly spontaneously giving a mixture of trans-and cis-diastereomers of 1,5,19,23-tetra-R′-3,21-di-R-1,5,19,23-tetraaza-3,21-diphospha[5.1.5.1]paracyclophanes as the major products. The trans-isomer (R is mesityl; R′ is methyl) was isolated in the individual state and structurally characterized by X-ray diffraction analysis. Sulfurization of macrocyclic diphosphines (R = Ph; R′ is 3-pyridylmethyl or 4-pyridylmethyl) gave the corresponding diphosphine disulfides, the trans-stereoisomer being isolated in the individual state. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1765–1774, September, 2007.  相似文献   

13.
Structures of eight triterpene glycosides, of which the 28-O-(2-O-acetyl-and 3-O-acetyl-α-L-rhamnopyranosyl)-(1→4)-O-β-D-glucopyranosyl-(1→ 6)-O-β-D-glucopyranosyl esters of hederagenin 3-O-β-D-glucopyranosyl-(1→ 2)-O-α-L-arabinopyranoside (J1a and J1b) were new, from Cussonia paniculata (Araliaceae) leaves were established using chemical and NMR spectroscopic methods. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 149–152, March–April, 2006.  相似文献   

14.
A non-ionic polymer (poly(vinyl alcohol) (PVA)) has been incorporated into the inorganic layers of calcium silicate hydrate (C–S–H) during precipitation of quasicrystalline C–S–H from aqueous solution. C–S–H and a C–S–H-polymer nanocomposite (C–S–HPN) material were synthesized and characterized by X-ray fluorescence (XRF), energy dispersive spectroscopy (EDS), 29Si magic angle spinning nuclear magnetic resonance (29Si MAS NMR) and 13C cross-polarization nuclear magnetic resonance (13C CP NMR) spectroscopy, atomic force microscopy (AFM), thermal conductivity, thermogravimetric analysis (TG) and differential thermal analysis (DTA). Thermal conductivity of PVA, C–S–H and C–S–HPN material was studied in the temperature range 25–50°C. C–S–HPN materials exhibited the highest thermal conductivity at 25 and 50°C. The thermal conductivity increases from 25 to 50°C are 7.03, 17.46 and 14.85% for PVA, C–S–H and C–S–HPN material, respectively. Three significant decomposition temperature ranges were observed on the TG curve of C–S–HPN material.  相似文献   

15.
The rate constants of the addition of phosphoryl radicals to fullerenes C60 and C70 were determined by the method of competitive reactions. The phosphoryl radicals were shown to be 1.5–3 orders of magnitude more reactive than the carbon-centered radicals. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1652–1655, September, 2000.  相似文献   

16.
Alkali phosphomolybdate glasses have been prepared by quenching melted mixtures of P2O5, MoO3 and A2O(A=Li, Na). The composition dependence of the transition temperature of glasses belonging to ternary A2O–(MoO3)2–P2O5 (A=Li, Na) systems is studied for several series of glasses corresponding to either a fixed A2O rate or a constant Mo/P ratio. The interpretation of the results is based on the presence of different types of molybdenum and phosphorous structural groups and P–O–M (M=P, Mo) linkages in glasses. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

17.
Several calcium silicate hydrate (C–S–H)-polymer nanocomposite (C–S–HPN) materials have been prepared by incorporating poly(acrylic acid) (PAA) into the inorganic layers of C–S–H during precipitation of quasicrystalline C-S-H from aqueous solution. The synthetic C–S–HPN materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS), thermogravimetry (TG), differential thermogravimetry (DTG) and differential scanning calorimetry (DSC). The XRD peaks of C–S–HPN materials suggest the intermediate organizations presenting both intercalation of PAA and exfoliation of C–S–H. The SEM images of C–S–H and C–S–HPN materials with different PAA contents exhibit the significant differences in their morphologies. Effects of the material compositions on the thermal stability of series of C–S–HPN materials along with PAA and C–S–H has been studied by TG, DTG and DSC. Three significant decomposition temperature ranges were observed on the TG curves of all C–S–HPN materials.  相似文献   

18.
The literature from the last 15–20 years on the synthesis of heteroatomic pyridine derivatives through the formation of pyridine carbon-heteroatom bonds is reviewed. Dedicated to Professor Henk van der Plas on his 70th birthday. For No. 2, see [1]. M. V. Lomonosov Moscow State University, Moscow 119899 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 437–494, April, 1999.  相似文献   

19.
M. V. Frunze Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 860–861, November–December, 1991.  相似文献   

20.
The structure of the new cycloartane glycoside cyclomacroside D, which was isolated from Astragalus macropus Bunge (Leguminosae) and is 24R-cycloartan-1α,3β,7β,24,25-pentaol 3-O-α-L-rhamnopyranoside–24-O-β-D-xylopyranoside, was proved. Presented at the 7th International Symposium on the Chemistry of Natural Compounds (SCNC, Tashkent, Uzbekistan, October 16–18, 2007). Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 48–50, January–February, 2009.  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