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951.
Yang M Wang W Yuan F Zhang X Li J Liang F He B Minch B Wegner G 《Journal of the American Chemical Society》2005,127(43):15107-15111
The synthesis of a block codendrimer (g3-PBE-b-g3-PMDC), composed of a third-generation poly(benzyl ether) (PBE) monodendron and an aliphatic polyether (PMDC) monodendron is reported. In THF/diiospropyl ether (1:1) the PMDC block functions as a "hydrophilic" block, while the PBE acts as a "hydrophobic" block. The codendrimer can form interdigitated layers leading to vesicle formation. Tapping mode atomic force microscopy (AFM), dynamic light scattering (DLS), and transmission electron microscopy (TEM) were used to characterize the vesicles. The effect of molecular architecture on the formation of the interdigitated layers and vesicles was studied. 相似文献
952.
Ai‐Hua Zhao Yan Zhang Zhao‐Hui Xu Jian‐Wen Liu Wei Jia 《Helvetica chimica acta》2004,87(12):3160-3166
Three new enmein‐type ent‐kaurenoids, i.e., the two pairs 1 and 2 of 20‐epimers and the (20R)‐isomer 3 , besides the seven known diterpenoids 4 – 10 , were isolated from the aerial parts of Isodon serra. Their structures were elucidated by spectroscopic techniques and X‐ray diffraction. The immunosuppressive effect for T‐lymphocytes proliferation induced by Con A in BALB/c mouse was evaluated for the isolates 1 – 10 . They all displayed a remarkable inhibitory effect, with multi‐glycosides of Tripterygium wilfordii as positive reference substance (Table 3). 相似文献
953.
Alexandra Alimova A. Katz Rakhi Podder Glenn Minko Hul Wei R. R. Alfano Paul Gottlieb 《Photochemistry and photobiology》2004,80(1):41-46
Native fluorescence spectroscopy was used for in situ investigations of two lipid‐containing bacteriophages from the cystovirus family as well as their Pseudomonad host cells. Both the viruses φ6 and φ12 and their bacterial host proteins contain the amino acid tryptophan (trp), which is the predominant fluorophore in UV. Within proteins, trp's structural environment differs, and the differences are reflected in their spectroscopic signatures. It was observed that the peak of the trp emission from both viruses was at 330 nm, a significantly shorter wavelength than trp in either the Pseudomonad host cells or the amino acid's chemical form. This allowed us to monitor the viral attachment process and subsequent lytic release of progeny virus particles by measurement of the trp emission spectra during the infection process. This work demonstrates that fluorescence may offer a novel tool to detect viruses and monitor viral infection of cells and may be part of a biodefense application. 相似文献
954.
The interaction of pinacyanol chloride(PC) with nucleic acids has been investigated by a series of experiments.Extensive hypochromism,appreciable peak shifts,isosbestic points and new peaks of the product of binding to nucleic acids in the spectra were observed.They showed that the interaction between PC and nucleic acids occurred.The results from absorption spectra of DNA,DNA melting,electrophoresis and fluorescence polarization studies have indicated that PC binds to DNA in nonintercalative way.Consistent with the nonintercalation,the studies of fluorescence titration and absorption titration specified that the binding of PC to nucleic acids occurred by an outside stacking binding,in which nucleic acids served for acting templates,The fact that the new absorption peaks of bound PC at ca,485nm are just close to the absorption bands of Haggregate of PC at high concentrations without DNA further supports the outside stacking binding mode,In addition,other evidence indicated that the interaction between PC and nucleic acids is not purely electrostatic. 相似文献
955.
Ming‐Liang Tong Wei Li Xiao‐Ming Chen Shao‐Liang Zheng Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(4):m232-m234
The title compound, [Cu2(C2H3O2)4(C11H9N)2] or [Cu2(MeCO2)4(phpy)2] (phpy is 4‐phenylpyridine), consists of centrosymmetric dimers in which the CuII atoms display a square‐pyramidal CuO4N coordination, with four acetate O atoms in the basal plane [Cu—O 1.975 (3)–1.987 (3) Å] and the phpy N atom in the apical position [Cu—N 2.150 (3) Å]. The Cu atoms are 2.654 (1) Å apart and are bridged by four acetate groups. The discrete dimers are extended into a three‐dimensional supramolecular array through intermolecular π–π‐stacking interactions. 相似文献
956.
Wei F Chen C Zhai L Zhang N Zhao XS 《Journal of the American Chemical Society》2005,127(15):5306-5307
Conventional single nucleotide polymorphism (SNP) assays, which based their detection on the stringency or temperature of the washing buffers, have encountered difficulties to distinguish a single base pair mismatch from a perfect match. In this study, scanning potential hairpin denaturation (SPHD) has been developed to detect SNP in a sensitive and reliable manner. Combined with hairpin oligonucleotide probes, scanning surface electric potential was used to induce a dissociation of double-stranded DNA around a unique "melting potential" (Vm), and it generated a high-contrast SNP recognition signal. A 21 base pair p53 gene segment was used to test this novel method. A single nucleotide mismatch to the hairpin probes caused an average of 400-800 mV difference in melting potential against the perfect match, while the error of this assay was lower than 20 mV. Experiments demonstrated that the hairpin stem was critical to the method. The concept of scanning potential hairpin denaturation could also be used extensively in different areas of nucleotide hybridization based assays. 相似文献
957.
A highly general, convenient, and inexpensive catalyst system was developed for the N-arylation of sulfonamides with aryl iodides or bromides by using 5-20 mol % of CuI as catalyst, 20 mol % of N-methylglycine (for aryl iodides) or N,N-dimethylglycine (for aryl bromides) as ligand, and K3PO4 as base. 相似文献
958.
959.
Hai‐Yang Liu Shi‐Jin Li Yi Zhao Wei Ni Xiao‐Jiang Hao Jun‐Zhu Li Yan Hua Bai‐Bo Xie Chen Qing Chang‐Xiang Chen 《Helvetica chimica acta》2007,90(10):2017-2023
Four new podocarpane‐type trinorditerpenenes, (5β,10α)‐12,13‐dihydroxypodocarpa‐8,11,13‐trien‐3‐one ( 1 ), (5β,10α)‐12‐hydroxy‐13‐methoxypodocarpa‐8,11,13‐trien‐3‐one ( 2 ), (5β,10α)‐13‐hydroxy‐12‐methoxypodocarpa‐8,11,13‐trien‐3‐one ( 3 ), and (3α,5β,10α)‐13‐methoxypodocarpa‐8,11,13‐triene‐3,12‐diol ( 4 ), together with four known diterpenes, 12‐hydroxy‐13‐methylpodocarpa‐8,11,13‐trien‐3‐one ( 5 ), spruceanol ( 6 ), ent‐3α‐hydroxypimara‐8(14),15‐dien‐12‐one ( 7 ), and ent‐3β,14α‐hydroxypimara‐7,9(11),15‐triene‐12‐one ( 8 ), were isolated from the twigs and leaves of Aleurites moluccana. Their structures were elucidated by means of comprehensive spectroscopic analyses, including NMR and MS. Except 8 , all compounds were evaluated for their cytotoxicity; compound 4 exhibited moderate inhibitory activity against Raji cells with an IC50 value of 4.24 μg/ml. 相似文献
960.
Two new ent‐abietane diterpenoids, macrophynin E ( 1 ) and macrophynin F ( 2 ), and a known related ent‐abietanoid (?)‐lambertic acid ( 3 ), together with four known ent‐kauranoids, were isolated from the roots and aerial parts of Isodon macrophylla, respectively. The structures of the new compounds were elucidated on the basis of spectroscopic‐data analysis and chemical correlations. 相似文献