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61.
A New Ceramide from the Ascomycete Tuber indicum 总被引:4,自引:0,他引:4
A new C-18 phytosphingosine derivative (1) was isolated from the fruiting bodies of Tuber indicum. Its structure was established as (2S,3S,4R,2′R)-2-N-(2′-hydroxytricosanoyl)-octadecan-1,3,4-triol by spectral and chemical methods. 相似文献
62.
A previous study of various A2B2O6O′ pyrochlore families by vibrational spectroscopy allowed the analysis of the ir and Raman spectra and the force fields of pyrochlore phases presenting structural defects. The spectra of the following compounds were compared: (i) ideal pyrochlore Cd2Ta2O7, (ii) lacunary Tl2Ta2O6, (iii) nonstoichiometric Pb1.5Ta2O6.5, and (iv) Pb2.3Ta2O7.3 exhibiting regular shear planes. If the tridimensional network of TaO6 octahedra is not modified and the perturbations concern only the A4O′ tetrahedra network, a slight modification of the vibrational spectra and a weak decrease in the TaO stretching and OTaO bending force constants are observed. But, if the octahedra network is perturbed, large modifications appear on the spectra, revealing unambiguously the existence of new types of bonds created by the defects in the structure. The Raman intense lines observed in the low frequency range in lead compounds is also discussed. 相似文献
63.
芫花 (DaphnegenkwaSieb.etZucc.)属于瑞香科植物[1] ,芫花的浸取液对棉蛉虫、稻螟虫、菜青虫、班蝥等害虫具有较好的杀虫效果 ,且对人畜无害 ,是一种理想的无公害农药[2 ] 。为了提高药效 ,更好地开发这种无公害农药 ,本文对芫花中杀虫有效成分的提取工艺与杀虫效果进行了初步研究。1 实验部分1 1 试剂和仪器苯 ,氯仿和 95 %的乙醇均为分析纯 ;岛津UV -2 40型紫外可见分光光度仪 ;FT -80ANMR仪。1 2 实验方法芫花枝条干粉 1 5 0 0g,加水 1 0 .0 0L煮沸 1 2小时 ,煮沸过程中陆续补加少量水分。将煮沸… 相似文献
64.
A simple method is proposed for the preparation of brassylic acid by the alkaline hydrolysis of 5,6,7,8,9,10,11,12,13,14-decahydrocyclododeca[1,2-d]pyrimidine(1H, 3H)dione-2,4, which is the product of the condensation of cyclododecanone with urea or biuret. The condensation of the cyclododecanone with thiourea proceeds differently, leading to 5,6,7,8,9,10,11,12,13,14-decahydrocyclododeca[1,2-d]pyrimidine(1H, 3H)spirocyclododecane-2-thione-4.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 226–229, January, 1992. 相似文献
65.
D. A. Armitage I. D. H. Towle 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):37-39
Abstract Aminosulfenates R2NSOR' have been prepared from aminosulfenyl chlorides and tin alkoxides. They form sulfenyl chlorides with chlorosilanes, bisaminosulfides with secondary amines and polysulfides with thiols. 相似文献
66.
Rui WU Qi YE Neng Yu CHEN Guo Lin ZHANG* Chengdu Institute of Biology the Chinese Academy of Sciences Chengdu Department of Chemistry Chemical Industry Lanzhou University Lanzhou Technical Centre Hua Sheng Group Co. L 《中国化学快报》2001,(3)
The plant Miliusa balansae Finet et Gagnep. is used in Chinese folk medicine for different symptom such as gastropathy and glomerulonephropathy. There is no report about its chemical investigation. In this study a new norditerpene with novel skeleton, named miliusate (1) was isolated, and its structure was established by spectral evidence.Compound 1 was obtained as white flaky crystal, mp 89-91(C; Its molecular formula C20H26O5 was provided by quasi-molecular ion [M+H]+ at m/z 347.17970 (c… 相似文献
67.
Wenqian Yang Fei Shao Jiexin Wang Tong Shen Yu Zhao Xueyan Fu Liming Zhang Hangying Li 《Molecules (Basel, Switzerland)》2022,27(22)
Background: Immunological liver injury (ILI) is a common liver disease and lacks potent drugs for treatment. Artemisia argyi Lévl. et Vant. (A. argyi), a medicinal and edible homologous plant usually used in diet therapy to cure various liver diseases, provides a great option for the prevention of ILI. Purpose: To investigate the effect that ethyl acetate extract of A. argyi (AaEA) on Concanavalin A (ConA)-induced ILI and the mechanism of regulating Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways. Methods: The chemical components of AaEA were studied by LC-MS. In animal experiments, the positive control group was administrated diammonium glycyrrhizinate (DIG, 100 mg/kg), while different doses of AaEA groups (AaEA-H, AaEA-M, AaEA-L) were pretreated with AaEA 2.00, 1.00, and 0.50 g/kg, respectively, by intragastric for seven days, once every day. Then, ConA (12.00 mg/kg) was used through tail intravenous injection to establish the ILI model. The blood samples and livers were collected to test the degree of liver dysfunction, inflammation, oxidative stress, histopathological changes, and cell apoptosis. Real-time PCR and Western blotting analysis were used to explain the mechanism of regulating Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways. Results: The way in which AaEA prevents liver damage in immunological liver injury (ILI) mice caused by ConA was investigated for the first time. Pretreatment with AaEA reduced the expression of ALT, AST, and inflammatory factors (TNF-α and IFN-γ). Meanwhile, AaEA also reduced MDA levels but upregulated the contents of IL-4, SOD, and GSH-px, alleviating oxidative stress induced by ILI. Western blotting and real-time PCR analysis demonstrated that AaEA could regulate the expression level and relative mRNA expression of key proteins on Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways. Finally, 504 components from AaEA were identified by LC-MS analysis, mainly including flavones, phenolic acids, and terpenoids with anti-inflammatory and liver protective activities, which highlights the potential of AaEA for diet treatment of ILI. Conclusion: AaEA can work against ConA-induced ILI in mice by regulating Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways, which has the potential to be a great strategy for the prevention of ILI. 相似文献
68.
David Ryckelynck 《Comptes Rendus Mecanique》2002,330(7):499-505
A model reduction method is proposed for finite element models. A previous computation of the state of the structure is not necessary. Residuals defined over the entire time interval and the Karhunen–Loève method provide basis functions. A non-incremental algorithm, from the LATIN method, is used to compute this basis functions. Because of the non-incremental feature, the reduced order model is representative for a large evolution of the state of the structure. To cite this article: D. Ryckelynck, C. R. Mecanique 330 (2002) 499–505. 相似文献
69.
Hedyotis caudatifolia Merr. et Metcalf. (HC), a folk medicine in Yao nationalities areas in China, was used to investigate the chemical constituents. Through silica gel and Sephadex LH-20 column chromatography, nine compounds were isolated and purified. By physical and chemical properties, IR, MS (EI-MS, high resolution EI-MS), 1D NMR (1H NMR, 13C NMR) and 2D NMR (HSQC, 1H–1H COSY, HMBC), their structures were identified as β-sitosterol (1), stigmasterol (2), scopolin (3), 2-hydroxy-1,7,8-trimethoxyanthracene-9,10-dione (4), oleanolic acid (5), ursolic acid (6), methyl barbinervate (7), β-daucosterol (8) and p-Hydroxybenzoic acid (9). These compounds were isolated from HC for the first time, and 4 a new anthraquinone whose biological activities are worth to be investigated in future. These compounds may contribute to the HC’s pharmacological effects on treating diseases, and may be used as candidates for control index in establishing the quality control standard of HC. 相似文献
70.
《Comptes Rendus Chimie》2015,18(10):1049-1073
Carbonaceous catalysts are promising materials for the low-temperature (< 523 K) process of NO reduction with ammonia. Based on literature and own experience of the authors, this review focuses on the possibilities to enhance their catalytic performance. It may be increased by the introduction of oxygen or nitrogen functionalities. So obtained materials may be used in SCR-NH3 either as catalysts or supports for transition metals oxides/hydroxides. Oxygen functionalities increase activity only to a small extent, but are necessary to prepare an efficient MeOx/AC catalyst. Nitrogen surface species lead to a considerable increase in DeNOx activity, as well as stability towards their oxidation to CO2. As the most efficient active components, oxides of V, Mn, Fe and Cu were found. H2O leads to the decrease of activity but for some catalysts additionally to the increase in selectivity. The understanding of SO2 influence needs more experimental data. There still are several open questions concerning more detailed mechanistic studies, and especially the role of nitrogen functionalities, H2O and SO2. 相似文献