共查询到20条相似文献,搜索用时 0 毫秒
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John A. Secrist III Robert M. Riggs Robert N. Comber John A. Montgomery 《Nucleosides, nucleotides & nucleic acids》2013,32(2-4):947-956
Abstract Phosphonate derivatives of ddA, ddC, ddI and ddT (5f, 5e, 5c, and 5a) were prepared by condensing the 5′-aldehydes with diphenyl triphenylphosphoranylidenemethylphosphonate, reducing the resultant olefins and hydrolyzing the phosphonate phenyl esters, sequentially, with base and then C. atrox phosphodiesterase. 相似文献
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《昆虫学文摘 (AE)》(AbstractsofEntomology)为昆虫学综合性检索刊物 ,在内容和形式上与上期介绍的《昆虫学文摘》(EntomologyAbstracts,简称EA)基本相同 ,但编辑和出版者不同。该刊由负责编辑发行《生物学文摘》(BiologicalAbstracts,简称BA)的BIOSIS文献机构编辑发行 ,其收录文献来源与《BA》相同 ,为《BA》的学科分卷。该刊始于 1 970年 ,每年 1卷 1 2期 ,按月出版 ,年终出年度总索引1册 ,至 2 0 0 0年已出版 3 1卷。各年第 1~ 1 2期除文摘内容外 ,还提供… 相似文献
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A theoretical study on the geometries and electronic structures of W@Au12AE (AE=NO+, BF, CN–, or BO–) was carried out to gain insight into interactions between W@Au12 and ligands isoelectronic with CO. The best configuration for the adsorption site is on-top type for all five complexes.
After complexing with boron ligands (BF or BO–), the axial Au–W bond distance in W@Au12 is lengthened notably, but NO+ has the opposite effect on the axial Au–W bond. A charge transfer and energy decomposition analysis shows that the metal–ligand
bonds have enhanced σ-donation strength from NO+ to BO–. Furthermore, the A–E bond strength in the complexes becomes weaker with stronger π-back-donation interactions. Finally,
W@Au12CO has the largest HOMO–LUMO gap, making it the most stable in terms of kinetic stability. 相似文献
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Mandal S Maity KK Bhunia SK Dey B Patra S Sikdar SR Islam SS 《Carbohydrate research》2010,345(18):2657-2663
Two different glucans (PS-I, water-soluble; and PS-II, water-insoluble) were isolated from the alkaline extract of fruit bodies of an edible mushroom Calocybe indica. On the basis of acid hydrolysis, methylation analysis, periodate oxidation, and NMR analysis ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit of these polysaccharides were established as: PS-I: →6)-β-D-Glcp-(1→6)-β-D-glcp-(1→6)-)-β-D-Glcp-(1→ α-D=Glcp (Water-soluble glucan). PS-II: →3)-β-D-Glcp-(1→3)-β-D-glcp-(1→3)-)-β-D-Glcp-(1→3)-β-D-Glcp-(1→ β-D-Glcp (Water-insoluble glucan, Calocyban). 相似文献
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Larry D. Barnes Michael N. Guy Glenda M. Roberson Richard W. Osgood 《Archives of biochemistry and biophysics》1982,214(1):239-247
A fluorescent analog of angiotensin II was synthesized by reacting fluorescein 5′-isothiocyanate with (Asp1, Ile5)-angiotensin II. Nα-(N-Fluoresceinthiocarbamoyl)-(Asp1, Ile5)-angiotensin II was purified by chromatography on DEAE-cellulose and Sephadex G-25. Analysis of the analog by thin-layer chromatography, thin-layer electrophoresis, and reversed-phase high-performance liquid chromatography indicated that the analog was free of angiotensin II and fluorescein 5′-isothiocyanate. N-Terminal sequence analysis demonstrated that fluorescein 5′-isothiocyanate reacted with the N-terminal aspartic acid residue of angiotensin II. Nα-(N-Fluoresceinthiocarbamoyl)-(Asp1, Ile5)-angiotensin II has an absorption maximum at 492 nm, and the value of the molar extinction coefficient, ?, is 7.7 × 104m?1 cm?1. The fluorescence emission maximum occurs at 520 nm. Infusion of the analog (0.69 μg/min/kg body wt) directly into the renal artery of an anesthetized rat reduced the blood flow by 12 to 27% within 2 min. Infusion of angiotensin II (0.48 μg/min/kg body wt) reduced renal arterial blood flow by 35 to 53% within 2 min. Saralasin, a partial agonist and antagonist of angiotensin II, inhibited the biologic effect of the fluorescent analog and angiotensin II by 75 and 70%, respectively. The purity, spectral properties, and in vivo biologic activity of Nα-(N-fluoresceinthiocarbamoyl)-(Asp1, Ile5)-angiotensin II indicate that this analog should facilitate characterization of angiotensin II receptors. 相似文献
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《Bioscience, biotechnology, and biochemistry》2013,77(10):1709-1711
For use as the internal standards in a quantitative analysis of natural jasmonic acid (JA) and methyl jasmonate (JAMe) by gas chromatography-mass spectrometry-selected ion monitoring, (±)-2-(2,3–2H2)JA and its methyl ester, (±)-2-(2,3–2H2)JAMe, were efficiently prepared from 2-(2–pentyl)-2-cyclopentenone through catalytic semi-deuteriogenation of acetylenic intermediates with deuterium gas in pyridine. 相似文献
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《Nucleosides, nucleotides & nucleic acids》2013,32(10):1939-1952
Abstract (E)-3′,5′-Diamino-5-(2-bromovinyl)-2′,3′,5′-trideoxyuridine (5), the diamino analogue of BVDU (1), was synthesized from BVDU. The protonation behavior of 5 has been studied by means of pH-metric measurements and NMR spectroscopy. This study allows the determination of the basicity constants and the stepwise protonation sites. Thus, the main species at physiological pH is the monoprotonated form. The conformational analysis of this nucleoside analogue was also carried out through 1H NMR spectroscopy. In addition, a convenient synthesis of N-3′ and N-5′ acylated derivatives was developed by regioselective enzymatic acylation. Thus, Candida antarctica lipase B (CAL-B) selectively acylated the 5′-amino group, thus furnishing nucleosides 8. On the other hand, immobilized Pseudomonas cepacia lipase (PSL-C) exhibited the opposite selectivity, conferring acylation at the 3′-amino group, thus affording derivatives 9. 相似文献
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1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino)propane hydrochloride (DDPH) is a potent α?-adrenoceptor antagonist that is currently under Phase II clinic trials. However, the fast metabolism has restricted its further use. In this paper, 11 DDPH analogs were designed according to the probable metabolism pathways of DDPH, and featured the structures of halogen, methyl, and cyano groups at the 3-, or 4-position of aromatic ring A to block the hydroxylation, and one hydroxyl group at the 3-, or 4-position of aromatic ring B to extend the duration time. These compounds were synthesized in moderate to good yields from the reductive amination of substituted phenoxyacetones with substituted phenylethylamines, and fully characterized with 1H NMR, IR, and HRMS. Biological evaluation indicated that most of the compounds exhibited strong blocking and moderate to good antihypertensive activities. It is clear that the compounds having 4-OH/3-OMe on group B exhibited higher blocking activities and longer duration time than their corresponding analogs having 4-OMe/3-OMe (and also 3-OH/4-OMe). Among them, compound 13 having bromo group at the 4-position of ring A and 4-OH/3-OMe on group B, exhibited the highest blocking activity, whereas compound 17 that had a methyl group at the 4-position of ring A and a hydroxyl group at the 4-position of ring B, was more active than potent DDPH in terms of both blocking and antihypertensive activities. In addition, the possible correlations between the blocking and antihypertensive activities are also briefly discussed. 相似文献
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Keith Smith Xiaojing Mu Zhaoqiang Li Andy M. Holland J. Stuart Woodhead Gamal A. El-Hiti 《Luminescence》2023,38(4):487-496
Several new acridinium esters 2 – 9 having their central acridinium ring bearing a 9-(2,5-dimethylphenoxycarbonyl), 9-(2,6-bis(trifluoromethyl)phenoxycarbonyl) or 9-(2,6-dinitrophenoxycarbonyl) group, and a 10-methyl, 10-(3-(succinimidyloxycarbonyl)propyl), 10-(5-(succinimidyloxycarbonyl)pentyl), or 10-(10-(succinimidyloxycarbonyl)decyl) group, have been synthesized and their chemiluminescent properties have been tested. The 2,5-dimethylphenyl acridinium esters emit light slowly (glow) when treated with alkaline hydrogen peroxide, while the 2,6-dinitrophenyl and 2,6-bis(trifluoromethyl)phenyl esters emit light rapidly (flash). The substituent at the 10 position affects the hydrolytic stabilities of the compounds. 相似文献
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Soumitra Mandal Sanjoy K. Bhunia Sukesh Patra Syed S. Islam 《Carbohydrate research》2010,345(18):2657-2243
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对胰岛素的研究使得许多生命科学中的重要问题被认识.然而对于胰岛素结构和功能关系,仍有许多不清楚的地方.在胰岛素A链的N端和C端各有一个螺旋区:A2-8和A12-18.杨士珍[1]的研究表明:缺失A12-18肽段的A链类似物虽然能和天然B链重组,但其重组产物只保留了天然胰岛素的约6%的体内外生物活性.这说明A12-18对胰岛素的生物活性十分重要.但是这一结果还不能说明是A12-18螺旋还是A12-18肽段对胰岛素的生物活性十分重要.根据Chuo-Fasman法,在含有Asn和Pro的肽段中不能形成… 相似文献
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目的:通过对黄皮酰胺全合成中间体(2R,3S,4S)-2-羟基-3-苯基-4-苯甲酰基-N-甲基-γ-内酰胺(化合物A)2位羟基的酯化,提高脂水分配系数(kP),考察对谷丙转氨酶活性的影响。方法:以化合物A为原料,通过酰化反应合成(2R,3S,4S)-2-(N,N-二乙氨基)甲酰氧基-3-苯基-4-苯甲酰基-N-甲基-γ-内酰胺(化合物B),重点考察了摩尔比、反应温度、反应时间等条件对反应的影响。化合物B结构已经元素分析、红外光谱、质谱及核磁共振氢谱确证。结果:化合物A和酰化剂以摩尔比2:3,在160℃下反应1h,目标化合物B。收率78.42%。结论:本合成路线及具体反应方法,具有试剂廉价易得、反应条件温和、后处理简便等优点,是一种较为实用的合成方法。 相似文献
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《基因组学与应用生物学》2016,(4)
TYRO3、AXL和MER受体是受体酪氨酸激酶亚家族之一,广泛地表达在哺乳动物神经、免疫、生殖、血液等系统多种细胞中,促进细胞存活、增殖和分化。本研究利用基因芯片技术筛选基因敲除的TYRO3~(~(-/-))AXL~(-/-)MER~(-/-)小鼠骨髓细胞中差异性表达的m RNA,并进行生物信息学分析。与正常小鼠骨髓细胞相比,TYRO3~(-/-)AXL~(-/-)MER~(-/-)小鼠骨髓细胞中差异表达基因探针共1 363条,其中表达上调的基因探针499条、下调的基因探针864条。GO功能富集分析发现上调的基因主要参与免疫反应,下调的基因主要参与造血。KEGG Pathway富集分析发现上调的基因主要参与细胞粘附分子和抗原呈递等信号通路。Real-time PCR验证5个差异基因,与芯片中表达变化趋势一致。因此TYRO3、AXL和MER受体共同参与调控机体的免疫反应和血细胞分化。 相似文献
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