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排序方式: 共有113条查询结果,搜索用时 31 毫秒
41.
Srivari Chandrasekhar Birudaraju Saritha Police Naresh Marelli Udayakiran Chada Raji Reddy Bharatam Jagadeesh 《Helvetica chimica acta》2008,91(7):1267-1276
The conformational control of a 14‐helix nucleating template, cis‐β‐furanoid sugar amino acid (FSAA), over a flexible δ‐amino acid, ornithine is studied in a FSAA‐ornithine cyclic tetrapeptide. Extensive NMR and MD studies reveal that the cyclic peptide adopts a three‐dimentional bowl‐shape cavity, which promotes six‐ and seven‐membered intra‐ and inter‐residue H‐bonding, in polar and non‐polar solvents, respectively. 相似文献
42.
Vibin M Vinayakan R John A Rejiya CS Raji V Abraham A 《Journal of colloid and interface science》2011,357(2):366-371
With excellent optical properties, quantum dots (QDs) have been made as attractive molecular probes for labeling cells in biological research. The purpose of the present work is to explore the possible role of silica-coated cadmium selenide (CdSe) QDs in the in vitro and in vivo cellular uptake and their subcellular localization. The in vitro uptake characteristics of silica-coated CdSe QDs were performed in cultured New Zealand rabbit adipose tissue-derived mesenchymal stem cells (RADMSCs) and Human cervical cancer cells (HeLa) using fluorescence microscopy after staining with 4,6-diamidino-2-phenylindole (DAPI). The in vitro results showed that the silica-coated CdSe QDs were efficiently taken up by the cells and it was localized in the intracellular vesicles giving strong fluorescence from the cytoplasm and nearby nucleus. Subsequently, the in vivo localization and distribution of QDs were studied by the hematoxilin stained semithin cryosections of tissues (~15 μm thickness) under fluorescence microscopy and ultrathin sections of tissues (~100 nm thickness) under confocal laser scanning microscopy at the distribution maxima. Our in vivo results confirmed the effective cellular uptake and even distribution pattern of QDs in tissues. Overall, these in vitro and in vivo results are represented with focus on internalization, subcellular localization and distribution of the QDs, in view of their potential applications in biomedical field. 相似文献
43.
A mild and metal-free access to 1,2,4-tri or 1,2,4,5-tetrasubstituted pyrroles has been developed by the reaction of Morita-Baylis-Hillman acetates of acetylenic aldehydes with amines and sulfonamides. This new protocol is based on K(2)CO(3)-promoted tandem allylic substitution/cycloisomerization reactions. 相似文献
44.
A metal mediated coordination-insertion pathway for the ring-opening polymerization (ROP) of L-lactide by an ionic {(NHC)(2)Ag}(+)X(-) (X = halide) type silver complex of N-heterocyclic carbene (NHC) has been investigated using the density functional theory (DFT) method. A clear insight into the lactide insertion process could be obtained by modeling two consecutive monomer addition steps with the first one mimicking chain initiation with the second representing a propagation step. In particular, in each of the cycles, the reaction initiates with the formation of a lactide coordinated species, [1+LL] and [2+LL] that transforms into a metal bound cyclic lactide intermediate, I([1+LL]→2) and I([2+LL]→3), which subsequently ring opens to give the lactide inserted products, 2 and 3. The estimated overall activation barrier for the initiation step is 42.0 kcal mol(-1) while the same for the propagation step is 31.5 kcal mol(-1). Studies on higher monomer insertions showed a decrease in the relative product energies as anticipated for an addition polymerization pathway. 相似文献
45.
Babić Z Crkvenčić M Rajić Z Mikecin AM Kralj M Balzarini J Petrova M Vanderleyden J Zorc B 《Molecules (Basel, Switzerland)》2012,17(1):1124-1137
Sorafenib is a relatively new cytostatic drug approved for the treatment of renal cell and hepatocellular carcinoma. In this report we describe the synthesis of sorafenib derivatives 4a-e which differ from sorafenib in their amide part. A 4-step synthetic pathway includes preparation of 4-chloropyridine-2-carbonyl chloride hydrochloride (1), 4-chloro-pyridine-2-carboxamides 2a-e, 4-(4-aminophenoxy)-pyridine-2-carboxamides 3a-e and the target compounds 4-[4-[[4-chloro-3-(trifluoromethyl)phenyl]carbamoylamino]-phenoxy]-pyridine-2-carboxamides 4a-e. All compounds were fully chemically characterized and evaluated for their cytostatic activity against a panel of carcinoma, lymphoma and leukemia tumour cell lines. In addition, their antimetabolic potential was investigated as well. The most prominent antiproliferative activity was obtained for compounds 4a-e (IC(50) = 1-4.3 μmol·L-1). Their potency was comparable to the potency of sorafenib, or even better. The compounds inhibited DNA, RNA and protein synthesis to a similar extent and did not discriminate between tumour cell lines and primary fibroblasts in terms of their anti-proliferative activity. 相似文献
46.
Pallavi ThakurB. Kumaraswamy G. Raji ReddyRakeshwar Bandichhor K. Mukkanti 《Tetrahedron letters》2012,53(29):3703-3705
The first stereoselective total synthesis of polyacetylene panaxjapyne C is described. The key reactions include regioselective opening of the epoxide and Cadiot-Chodkiewicz cross-coupling reactions. l-Ascorbic acid was used as a chiral pool material for the construction of the both terminal acetylenes. 相似文献
47.
Mohamed Jleli Vesna Čojbašić Rajić Bessem Samet Calogero Vetro 《Journal of Fixed Point Theory and Applications》2012,12(1-2):175-192
In this paper, we establish certain fixed point theorems in metric spaces with a partial ordering. Presented theorems extend and generalize several existing results in the literature. As application, we use the fixed point theorems obtained in this paper to study existence and uniqueness of solutions for fourth-order two-point boundary value problems for elastic beam equations. 相似文献
48.
Summary A study has been made of the high-temperature reactions taking place in the graphite matrix of a d. c. carbon arc. A special evaporator was used for controlled heating of samples. Volatilisations were investigated spectrographically, and X-ray diffraction was used for detection of any new phases formed. The presence of sodium fluoride or chloride was found to enhance the volatilisation of the elements investigated, but no evidence was found for formation of their fluorides or chlorides.
Zusammenfassung Die in der Graphitmatrix eines Gleichstrombogens bei hohen Temperaturen stattfindenden Reaktionen wurden untersucht. Ein spezieller Verdampfer wurde für das kontrollierte Erhitzen der Proben verwendet. Verflüchtigungen wurden spektrographisch festgestellt, zum Nachweis etwa neu entstandener Phasen diente die Röntgendiffraktion. Die Anwesenheit von NaF oder NaCl begünstigt die Verflüchtigung der untersuchten Elemente, ohne daß Anzeichen für die Bildung ihrer Fluoride oder Chloride gefunden werden konnten.相似文献
49.
The thermal decompositions of the complexes K3[M(ox)3]3H2O(M=Al, Cr, Mn, Fe, Co; ox=C2O42–) were studied. Dehydration of the complexes occurs up to 200°C, this being a three-step process for M=Al, Cr, Mn and Co, and a two-step process for M=Fe. Decomposition of the dehydrated complexes proceeds in several steps. For M=Al, Cr and Fe, the decomposition takes place with the evolution of CO, whereas for M=Mn and Co the decomposition of the oxalate ligand yields solid C besides CO. The temperature of CO liberation decreases in the series Cr<Al<Co<Mn<Fe. For M=transition metal, this trend can be explained by the fact that the strength of the C—C bond in the oxalate ligand decreases in the series Cr<Co<Mn<Fe.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
50.
Ch. Raji Reddy K. Vijeender P. Bibhuti Bhusan P. Phani Madhavi S. Chandrasekhar 《Tetrahedron letters》2007,48(15):2765-2768
The potential utility of polymethylhydrosiloxane (PMHS) as a reducing agent for reductive N-alkylation of aromatic amines and nitro compounds using nitriles as an alkylating agent and Pd(OH)2/C as a catalyst is described. The application of this method for the synthesis of several heterocyclic compounds is also reported. 相似文献