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31.
The chemical composition of the essential oils of the flowers and leaves of Anthemis hyalina were analyzed by GC and GC-MS for the first time. The oils were found to contain seventy-two components. cis-Chrysanthenyl acetate (14.9% and 17.8%), camphor (11.6% and 1.7%), terpinen-4-ol (8.3% and 1.2%), germacrene-D (5.1% and
2.1%), β-caryophyllene (4.1% and 5.4%), myrcene (3.6% and 16.9%), bicyclogermacrene (3.5% and 0.9%), α-pinene (2.3% and 4.1%), cis-β-ocimene (2.1% and 4.3%) and isospathulenol (0.4% and 4.3%) were found to be the major constituents of the oils of flowers
and leaves respectively.
Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 428–429, September–October, 2006. 相似文献
32.
The first part of the paper deals with a critical discussion of the methodical basis of essential work of fracture (EWF) concept with respect to the specimen geometry (especially the notch depth) and application to polymers. In the second part, an in situ testing device, which combines a tensile testing machine with an optical strain-field measuring system, has successfully demonstrated possibility of characterization of fracture behaviour of polystyrene-polybutadiene block copolymers and block copolymer/homopolymer blends as examples of nanostructured polymer materials. It has been shown that knowledge of the time evolution of the strain field close to the crack tips leads to a simple verification of the basic precondition for the applicability of the EWF concept, the precondition “plastic zone coalescence-before-stable crack propagation”. 相似文献
33.
34.
35.
有机相中α-氰基-3-苯氧基苄醇乙酯的酶促醇解反应 总被引:1,自引:1,他引:1
研究了有机相中脂肪酶催化α-氰基-3-苯氧基苄醇乙酯的醇解化反应。制备α -氰基-3-苯氧基苄醇。考察了酶、溶剂、醇、醇用量、溶剂水含量以及底物浓度等 因素对反应的影响,结果表明Novozym435脂肪酶催化活性最高,经实验确定的最佳 条件为:脱水甲苯为溶剂,正辛醇为酰基受体,正辛醇、酯的摩尔比为1.5:1,酶 量为8 mg/mL时的最佳底物浓度为108.13 mmol/L,在上述条件下反应30 h酯的转化 率 > 96%。 相似文献
36.
Ammonium acetate was found to catalyze efficiently the selective deprotection of aromatic acetates in the presence of various sensitive functionalities in aqueous methanol under neutral conditions at room temperature to yield the corresponding phenols in excellent yields. The method has been utilized for deprotection of acetates of several naturally occurring bioactive phenolic compounds and for preparation of venkatasin, a natural coumarino-lignan, from the anticancer compound cleomiscosin A. 相似文献
37.
An efficient and a quick microwave‐assisted synthesis of benzimidazoles and trisubstituted imidazoles was developed. Three benzimidazoles were obtained as a result of the condensation of 1,2‐phenylenediamine with carboxylic acids and acetoacetic ester without catalyst. A series of trisubstituted imidazoles were synthesized by condensation of benzil, aromatic aldehyde and ammonium acetate in the presence of glacial acetic acid. 相似文献
38.
以过硫酸铵为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,淀粉与丙烯酸/醋酸乙烯酯混合单体通过接枝共聚,制备了吸水及耐盐性能均较好的淀粉接枝丙烯酸/醋酸乙烯酯高吸水性树脂(CGAV)。最佳工艺条件为:淀粉10.0 g,m(混合单体)∶m(淀粉)=4∶1,w(引发剂)=0.3%,w(交联剂)=0.05%,于45℃反应2h~3 h。在最佳工艺条件下制得的CGAV吸去离子水率760 g.g-1,吸0.9%NaC l水溶液率68 g.g-1。 相似文献
39.
Santi Tungprapa Tanarinthorn Puangparn Monchawan Weerasombut Ittipol Jangchud Porntiva Fakum Somsak Semongkhol Chidchanok Meechaisue Pitt Supaphol 《Cellulose (London, England)》2007,14(6):563-575
This paper reports an investigation of the effects of solvent system, solution concentration, and applied electrostatic field
strength (EFS) on the morphological appearance and/or size of as-spun cellulose acetate (CA) products. The single-solvent
systems were acetone, chloroform, N,N
-dimethylformamide (DMF), dichloromethane (DCM), methanol (MeOH), formic acid, and pyridine. The mixed-solvent systems were
acetone–DMAc, chloroform–MeOH, and DCM–MeOH. Chloroform, DMF, DCM, MeOH, formic acid, and pyridine were able to dissolve CA,
forming clear solutions (at 5% w/v), but electrospinning of these solutions produced mainly discrete beads. In contrast, electrospinning of the solution of
CA in acetone produced short and beaded fibers. At the same solution concentration of 5% (w/v) electrospinning of the CA solutions was improved by addition of MeOH to either chloroform or DCM. For all the solvent systems
investigated smooth fibers were obtained from 16% (w/v) CA solutions in 1:1, 2:1, and 3:1 (v/v) acetone–DMAc, 14–20% (w/v) CA solutions in 2:1 (v/v) acetone–DMAc, and 8–12% (w/v) CA solutions in 4:1 (v/v) DCM–MeOH. For the as-spun fibers from CA solutions in acetone–DMAc the average diameter ranged between 0.14 and 0.37 μm
whereas for the fibers from solutions in DCM–MeOH it ranged between 0.48 and 1.58 μm. After submersion in distilled water
for 24 h the as-spun CA fibers swelled appreciably (i.e. from 620 to 1110%) but the physical integrity of the fibrous structure
remained intact. 相似文献
40.
Dan Donescu Sever Serban Kristiana Gosa Cristian Petcu 《Central European Journal of Chemistry》2005,3(1):10-27
The possibility to prepare hybrids made by poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA) and/or poly(ethyl
acrylate) (PEtA) with TiO2 was studied. The processes of polymer formation-radical polymerization and sol-gel process for inorganic network —were achieved
simultaneously. Due to a high reactivity of titanium isopropoxide (TIP) in the sol-gel process, a complexant comonomer, allyl
acetoacetate (AlAcAc), was used. Covalent bonds between polymer and inorganic chains were obtained by addition of trialkoxysilane
derivates with vinyl (VTES) or methacryloyl (MPTS) groups. The presence of TIP inhibits the radical polymerization of vinyl
acetate (VAc). The PVAc-TiO2 hybrids were produced by the sol-gel process of TIP in the presence of pre-obtained PVAc. Except for VTES and MPTS, trialkoxysilane
derivates with methyl (MeTES), octyl (OTES) and phenyl (PTES) groups were used. The thermal stability of hybrids is strongly
affected by TiO2 presence and by the type of trialkoxysilane derivates. The thermal stability of PVAc hybrids decreases in the presence of
TiO2 inorganic network. The glass transition temperature of polymers increases in the presence of the inorganic network. 相似文献