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排序方式: 共有197条查询结果,搜索用时 500 毫秒
191.
Moustapha B Marina GA Raúl FO Raquel CM Mahinda M 《Molecules (Basel, Switzerland)》2011,16(11):9397-9403
A phytochemical study of the methanol-soluble fraction of an aqueous extract of a sample of Psittacanthus calyculatus collected from the host plant Prosopsis laevigata (Smooth Mesquite) using several techniques, including co-chromatography coupled with UV detection, chromatographic purifications and IR, NMR and MS studies, resulted in the identification of gallic acid, two flavonol-3-biosides and the nonprotein amino acid N-methyl-trans-4-hydroxy-L-proline. 相似文献
192.
A novel fiber design of large mode area (LMA) all-glass leakage channel fibers (LCF) with triangular core is proposed. The effective single mode behavior and bend characteristics of the fiber are numerically investigated. The designed LCFs can achieve LMA larger than 1400 μm2, effective single mode operation and low bend loss by carefully choosing the diameters of the fluorine-doped silica rods. 相似文献
193.
Dora C.S. Costa Vânia F. Pais Artur M.S. Silva José A.S. Cavaleiro Uwe Pischel João P.C. Tomé 《Tetrahedron letters》2014
One of the applications of cationic porphyrins is their use in microbial photodynamic inactivation (PDI). For this purpose there is a constant quest for new cationic photoactive derivatives. In this work, we synthesized and fully characterized a new porphyrin 3a and the corresponding cationic derivative 3b. The results presented here show that meso-tetrakis(pentafluorophenyl)porphyrin (TPPF20, 1) can be used as scaffold to prepare different soluble compounds with interesting photophysical properties. 相似文献
194.
Hindson BJ Gutierrez DM Ness KD Makarewicz AJ Metz TR Setlur US Benett WB Loge JM Colston BW Francis PS Barnett NW Dzenitis JM 《The Analyst》2008,133(2):248-255
We present a fully automated DNA purification module comprised of a micro-fabricated chip and sequential injection analysis system that is designed for use within autonomous instruments that continuously monitor the environment for the presence of biological threat agents. The chip has an elliptical flow channel containing a bed (3.5 x 3.5 mm) of silica-coated pillars with height, width and center-to-center spacing of 200, 15, and 30 microm, respectively, which provides a relatively large surface area (ca. 3 cm(2)) for DNA capture in the presence of chaotropic agents. We have characterized the effect of various fluidic parameters on extraction performance, including sample input volume, capture flow rate, and elution volume. The flow-through design made the pillar chip completely reusable; carryover was eliminated by flushing lines with sodium hypochlorite and deionized water between assays. A mass balance was conducted to determine the fate of input DNA not recovered in the eluent. The device was capable of purifying and recovering Bacillus anthracis genomic DNA (input masses from 0.32 to 320 pg) from spiked environmental aerosol samples, for subsequent analysis using polymerase chain reaction-based assays. 相似文献
195.
Lockett MR Phillips MF Jarecki JL Peelen D Smith LM 《Langmuir : the ACS journal of surfaces and colloids》2008,24(1):69-75
A tetrafluorophenyl (TFP) ester-terminated self-assembled monolayer (SAM) for the fabrication of DNA arrays on gold surfaces is described. Activated ester SAMs are desirable for biomolecule array fabrication because they readily react with amine-containing molecules to form a stable amide linkage. N-Hydroxysuccinimide (NHS) ester SAMs are commonly used for this purpose but are subject to a competing hydrolysis side reaction, limiting their effectiveness under basic conditions. TFP was evaluated here as an alternative activated ester leaving group with a potentially greater stability under basic conditions. It is shown that TFP SAMs are much more stable to basic pH than their NHS analogs and are also more hydrophobic, which is an advantage in the fabrication of high-density spotted arrays. DNA arrays prepared on TFP SAMs at pH 10 have a 5-fold greater surface density of DNA molecules, reduced fluorescence background, and smaller spot radii than those prepared on NHS SAM analogs. 相似文献
196.
López-Cara LC Carrión MD Camacho ME Gallo MA Espinosa A Choquesillo-Lazarte D Gonzalez-Pérez JM Entrena Guadix A 《Magnetic resonance in chemistry : MRC》2008,46(9):878-885
The (1)H and (13)C NMR resonances of 22 1-alkyl-pyrazole and 25 1-alkyl-pyrazoline derivatives were assigned completely using the concerted application of one- and two-dimensional experiments (DEPT, gs-HMQC and gs-HMBC). Nuclear Overhauser enhancement (NOE) effects, conformational analysis and X-ray crystallography confirm the preferred conformation of those compounds. 相似文献
197.
Ohkanda J Strickland CL Blaskovich MA Carrico D Lockman JW Vogt A Bucher CJ Sun J Qian Y Knowles D Pusateri EE Sebti SM Hamilton AD 《Organic & biomolecular chemistry》2006,4(3):482-492
A series of imidazole-containing peptidomimetic PFTase inhibitors and their co-crystal structures bound to PFTase and FPP are reported. The structures reveal that the peptidomimetics adopt a similar conformation to that of the extended CVIM tetrapeptide, with the imidazole group coordinating to the catalytic zinc ion. Both mono- and bis-imidazole-containing derivatives, 13 and 16, showed remarkably high enzyme inhibition activity against PFTase in vitro with IC50 values of 0.86 and 1.7 nM, respectively. The peptidomimetics were also highly selective for PFTase over PGGTase-I both in vitro and in intact cells. In addition, peptidomimetics and were found to suppress tumor growth in nude mouse xenograft models with no gross toxicity at a daily dose of 25 mg kg(-1). 相似文献