排序方式: 共有34条查询结果,搜索用时 15 毫秒
1.
Ralf Freund Siavosh Mahboobi Klaus Noack Peter Schonhlzer Karl Bernauer 《Helvetica chimica acta》1990,73(2):439-454
C-(Alkoxycarbonyl)formimines of type 15–18 were derived from the 2-substituted tryptamines 2 , 9 , 10 , and 11 and transformed with tosyl chloride into tricyclic 3-spiroindoles of types 19–22 (Scheme 3). The influence of the homochiral alkoxy moieties A–D on the stereochemical outcome of this reaction was studied. Good-to-excellent diastereoselectivities were observed with the (?)-8-(phenylmenth-3-yl)oxy group ( B ) as homochiral auxiliary. The structures of the tricycles 4 , (2′R,3S)- 19B , and (2′S,3R) 20C were established by X-ray analysis, the structures of the others by NOE and CD studies, and by chemical correlation. Possibilities to explain the steric course of the spirocyclizations are discussed. 相似文献
2.
Siavosh Mahboobi Andreas Sellmer Thomas Burgemeister Alexei Lyssenko Dieter Schollmeyer 《Monatshefte für Chemie / Chemical Monthly》2004,135(3):333-342
The synthesis of the naturally occurring and biologically active alkaloids 1 and 2, first isolated from the red ascidian Botryllus leachi by Duran et al. [1], is described and the structure proposed for Botryllazine B (1) is confirmed. The analytical data for 2-(p-hydroxybenzoyl)-4-(p-hydroxyphenyl)imidazole (2) are discussed and compared with the literature. With special emphasis of 1H NMR data the tautomerism of aroylimidazolemethanones is described. 相似文献
3.
Two main existence conditions for solutions of variational relation problems are established without convexity. The first one is based on a finite solvability property and the second one on generalized KKM mappings. These conditions unify and strengthen several existing results in the literature on the topic. A model of satisficing process by rejection is considered which gives an economic interpretation of the introduced concepts. 相似文献
4.
R. AminiA.A. Sarabi 《Applied Surface Science》2011,257(16):7134-7139
Sodium nitrite has been used as an accelerating agent in phosphating bath to improve its properties. However, it is well known that sodium nitrite is a carcinogenic component in phosphating sludge. In this study, it has been aimed to replace sodium nitrite by an environmentally friendly accelerating agent. To this end, sodium dodecyl sulfate (SDS) was used in phosphating bath to improve the phosphate coating formation on an AZ31 magnesium alloy. The effect of SDS/sodium nitrite ratio on the phosphated samples properties was also studied. Using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), direct current (DC) polarization and electrochemical impedance spectroscopy (EIS) the properties of phosphated magnesium samples were studied.Results showed uniform phosphate coating formation on the magnesium sample mostly in hopeite phase composition. In addition, a denser and less permeable coating can be obtained at these conditions. The corrosion resistance of the phosphated samples was superiorly improved using higher SDS concentration in the phosphating bath. 相似文献
5.
This paper provides a version of second-order Taylor’s expansion for vector-valued functions. Also, a necessary and sufficient condition for Pareto optimality is obtained. The results are given in terms of pseudo-Hessian matrices introduced in question. 相似文献
6.
Determination of concentration of major elements such as Ca, Si, Al, and Fe in cement is very important for quality control during its production, correct classification according to the existing standards, and thus for appropriate use in the construction industry. For this purpose, neutron activation analysis is very suitable. In this preliminary theoretical work, the irradiation and consecutive measurement of the percentage of the constituent elements in different cement samples were done using MCNPX with γ-ray spectra as the output. Specific peaks of Ca, Si, Al, and Fe obtained from these spectra were used as input for artificial neural network (18 of them for training and 8 for testing) resulting in the determination of each element in the given sample. The mean absolute errors of the results are less than 0.4%, which is very promising for the future experimental work where the uncertainties are usually one order higher. 相似文献
7.
Siavosh Mahboobi Andreas Sellmer Thomas Burgemeister Alexei Lyssenko Dieter Schollmeyer 《Monatshefte für Chemie / Chemical Monthly》2004,47(8):333-342
The synthesis of the naturally occurring and biologically active alkaloids 1 and 2, first isolated from the red ascidian Botryllus leachi by Duran et al. [1], is described and the structure proposed for Botryllazine B (1) is confirmed. The analytical data for 2-(p-hydroxybenzoyl)-4-(p-hydroxyphenyl)imidazole (2) are discussed and compared with the literature. With special emphasis of 1H NMR data the tautomerism of aroylimidazolemethanones is described. 相似文献
8.
Ghobad Mohammadi Mohammad Mahdi Zangeneh Akram Zangeneh Zahra Minoosh Siavosh Haghighi 《应用有机金属化学》2020,34(1):e5136
The aim of the recent research was to investigate the anti-breast cancer effects of silver nanoparticles using Phoenix dactylifera seed ethanolic extract (AgNPs). After preparation of Phoenix dactylifera seed extract, GC/MS was performed to detect the compounds. The findings indicated that 9-Octadecenoic acid (Z)- methyl ester (40.95%) and Dodecanoic acid methyl ester (20%) were the most frequent constituents found in P. dactylifera. These nanoparticles were spherical with a size range of 17-19 nm and characterized using various analytical techniques including UV–Vis absorption spectroscopy to determine the presence of AgNPs in the solution. We studied functional groups of P. dactylifera extract in the reduction and capping process of AgNPs by FT-IR, crystallinity and FCC planes by X-ray diffraction (XRD) pattern and surface morphology, shapes, and size of AgNPs by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). DPPH free radical scavenging test was used to test the antioxidant properties of P. dactylifera and AgNPs, which revealed high antioxidant potential similar to butylated hydroxy toluene (BHT) as the positive control. The results of cytotoxicity analysis indicated that P. dactylifera and AgNPs were toxic for MCF-7 cells. In vivo design, induction of breast cancer was done by 7,12-Dimethylbenz[a] anthracene (DMBA) in 50 animals. After 10 days, the animals were randomly divided into six subgroups, including healthy control, untreated control, two groups receiving the P. dactylifera at 2 and 6 mg/kg and two groups receiving the AgNPs at 2 and 6 mg/kg concentrations. Both doses of P. dactylifera and AgNPs (especially AgNPs6) significantly (p ≤ 0.05) reduced the weight and volume of liver, mammary gland, kidney, spleen, ALP, AST, ALT, GGT, cholesterol, LDL, triglyceride, total and conjugated bilirubin, urea, creatinine, glucose, ferrous, ferritin, erythropoietin, GR, IL1, IL6, IL12, IL18, IFNY, and TNFα and increased HDL, total protein, albumin, WBC, lymphocyte, neutrophils, platelet, RBC, Hb, PCV, MCV, MCH, MCHC, SOD, CAT, GPx, IL4, IL5, IL10, IL13, and IFNα compared to the untreated group. Moreover, P. dactylifera and AgNPs (especially AgNPs6) significantly (p ≤ 0.05) treated breast cancer with reduction of organs free of metastasis compared to the untreated group. Seemingly, the AgNPs can be used for the treatment of breast cancer. 相似文献
9.
Ralf Freund Siavosh Mahboobi Klaus Noack Peter Schönholzer Karl Bernauer 《Helvetica chimica acta》2005,88(12):3274-3275
10.
Mahmood Tajbakhsh Majid M. Heravi Farajollah Mohanazadeh Siavosh Sarabi Mitra Ghassemzadeh 《Monatshefte für Chemie / Chemical Monthly》2001,132(10):1229-1231
Summary. N-Methylpiperidinium chlorochromate adsorbed on alumina was found to be an efficient and selective reagent for the mild oxidative
cleavage of oximes.
Received March 1, 2001. Accepted March 22, 2001 相似文献