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排序方式: 共有552条查询结果,搜索用时 31 毫秒
61.
Physics of Atomic Nuclei - In this paper, two options for damping higher order modes (HOMs) using rectangular waveguides and corrugated cylindrical waveguides are considered. The tuning of the two... 相似文献
62.
M. I. Medvedeva N. Z. Tugusheva L. M. Alekseeva M. A. Kalinkina V. A. Parshin V. V. Chernyshev V. I. Levina N. B. Grigor’ev A. S. Shashkov V. G. Granik 《Russian Chemical Bulletin》2010,59(12):2247-2258
Amidinohydrazones were prepared by the condensation of 4-arylamino-2-oxo-5-formyl-1,2-dihydropyridine-3-carbonitriles and
4-arylamino-2-oxo-1,2-dihydropyridine-3-carbaldehydes with aminoguanidinium carbonate with the purpose to investigate their
biological activity as putative NO donors. The reaction of 5- и 3-formylpyridones with diguanidinium carbonate was studied.
The formation of stable complexes of 4-arylamino-5-formyl-2-oxo-1,2-dihydropyridine-3-carbonitriles with aminoguanidine and
guanidine was discovered. Amidinohydrazones obtained possess antiinflammatory, antidiabetic, and antihypertensive activities. 相似文献
63.
I. V. Mikhura A. A. Formanovskii A. S. Shashkov 《Russian Journal of Organic Chemistry》2010,46(8):1116-1120
The reaction of benzil with methyl alkyl ketones gave three isomeric cyclopentenone derivatives, 2-substituted and cis- and trans-5-substituted 4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones. cis- and trans-2,5-Disubstituted 4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones were formed in analogous reaction of benzil with dialkyl ketones.
The structure of the products was confirmed by 1H NMR spectroscopy and molecularmechanics calculations. 相似文献
64.
Sparse asymptotic minimum variance based bearing estimation algorithm for a single vector hydrophone
For underwater target detection using a single vector hydrophone, sparse asymptotic minimum variance(SAMV) method is used to estimate the target bearing. The SAMV discretizes the entire scanning space and the target bearing is located at the position of the discrete direction. The SAMV algorithm utilizes the sparsity of the spatial signal to improve the estimation performance of the target bearing. Background noise level(BNL) of the bearing estimation of SAMV algorithm is lower than those of the conventional beam forming(CBF)method and minimum variance distortionless response(MVDR) method for different signal noise ratios(SNRs). When the SNR is higher than 0 d B, the direction-finding error of this algorithm is less than 2°. Moreover, the SAMV algorithm has a better dimensional orientation resolution capability. The experimental results show that the SAMV algorithm gives a bearing and time recording map with a lower BNL, which effectively verifies the effectiveness of SAMV algorithm in terms of underwater target detection. 相似文献
65.
Ewa Katzenellenbogen Nina A. Kocharova Georgy V. Zatonsky Maria Bogulska Danuta Witkowska Aleksander S. Shashkov 《Journal of carbohydrate chemistry》2013,32(5):545-558
ABSTRACT Lipopolysaccharide (LPS) of Hafnia alvei 23 has an acid-labile O-specific polysaccharide (OPS) with a pentasaccharide-phosphate repeating unit containing D-Glc1P, D-GlcNAc, L-Fuc, 6-deoxy-D-talose (D-6dTal), 4-acetamido-4,6-dideoxy-D-glucose (D-Qui4NAc), and an O-acetyl group. A partially degraded OPS was obtained by hydrolysis of LPS with 0.25 M sodium acetate in aqueous 0.5% acetic acid. Fractionation of LPS on Sephadex G-200 in DOC buffer allowed isolation of long-chain LPS species which, together with OPS, were studied by methylation analysis, chemical degradations (O-deacetylation, dephosphorylation with 48% hydrofluoric acid, Smith degradation), and 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, NOESY, and H-detected 1H,13C heteronuclear single-quantum coherence (HSQC) experiments. The following structure of the repeating unit of OPS was established: 相似文献
66.
分别采用全多孔型硅胶基键合强阴离子交换柱与氨丙基键合硅胶柱,在低波长 200 nm 处检测,分离测定了磷霉素 探讨了流动相条件,如p H 值、离子强度等对磷霉素保留及分离选择性的影响,优化分离条件,建立了一种测定磷霉素的高效液相色谱新方法方法简便、快速 相似文献
67.
S. A. Savina V. M. Lyubchanskaya L. M. Alekseeva A. S. Shashkov V. G. Granik 《Russian Chemical Bulletin》2007,56(11):2298-2304
Condensation of tetronic acid with 2-cyano-, 2-ethoxycarbonyl-, 2-carboxy-, and 2-aminoanilines gave novel furoquinolines
and furobenzodiazepines.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2220–2226, November, 2007. 相似文献
68.
V. U. Khuzhaev I. Zhalolov K. K. Turgunov B. Tashkhodzhaev M. G. Levkovich S. F. Aripova A. S. Shashkov 《Chemistry of Natural Compounds》2004,40(3):269-272
The newdimeric alkaloid arundaphine, a tryptamine-tryptamine base, was isolated from roots and rhizomes of Arundo donax (Poaceae). Spectral data and an x-ray structure analysis established its structure as 1-[3-(2-dimethylaminoethyl)-5-hydroxy-1H-4-indolyl]-3-hydroxy-3-(2-methylaminoethyl)-2-indolinone. 相似文献
69.
N. E. Mashchenko R. Gyulemetova P. K. Kintya A. S. Shashkov 《Chemistry of Natural Compounds》1990,26(5):552-555
The chemical composition and structures of the steroid glycosides forming the active principle of the preparation “tribestan,”
which is used for treating impotence and female infertility, have been studied. It has been shown that together with trillin,
prosapogenin A of dioscin, trillarin, dioscin, gracillin, protodioscin, and protogracillin, tribestan contains a diosgenin
rhamnoglucoside sulfated in position 4 of the glucose residue, the structure of which has been shown by chemical and physicochemical
methods.
Institute of Ecological Genetics, Academy of Sciences of the Moldavian SSR, Kishinev. Center for Biogenic Stimulators, Sofia,
Bulgaria. N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Khimiya
Prirodnykh Soedinenii, No. 5, pp. 649–652, September–October, 1990. 相似文献
70.
M. A. Khodzhaeva Z. F. Ismailov E. S. Kondratenko A. S. Shashkov 《Chemistry of Natural Compounds》1982,18(1):20-24
By fractionating the total glucofructan from the bulbs ofAllium sativum L. a homogeneous glucofructan with a molecular weight of 2300 has been isolated. On the basis of its characteristics, a comparison of IR and13C NMR spectra, and the results of periodate and chromium trioxide oxidation and of methylation, it has been established that this glucofructan is a new type of compound of this class, containing both inulin (2 → 1) and levan (2 → 6) glycosidic bonds. 相似文献