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排序方式: 共有397条查询结果,搜索用时 15 毫秒
391.
392.
Shcharbin D Pedziwiatr E Nowacka O Kumar M Zaborski M Ortega P de la Mata FJ Gómez R Muñoz-Fernandez MA Bryszewska M 《Colloids and surfaces. B, Biointerfaces》2011,83(2):464-391
A new mechanism of gene expression inhibition has been discovered as RNA interference, in which the ability of double-stranded RNA to stimulate specific degradation of an mRNA target with a complementary sequence to one of the double-stranded RNA strands. Water-soluble carbosilane dendrimers containing ammonium or amine groups at their periphery are biocompatible molecules that may be good candidates as non-viral carriers of small interfering RNA. In studying the formation of complex between anti-HIV siRNA siGAG1 and carbosilane dendrimers NN8 and NN16 by circular dichroism, fluorescence, and zeta-potential, the size of nanoparticles formed has been estimated by dynamic light scattering. At a charge ratio of 1:3-4 (siGAG1:dendrimer), the dendriplexes formed were in the size range of 250-350 nm. 相似文献
393.
A mild method for the deprotection of tetrahydropyranyl (THP) ethers catalyzed by iron(III) tosylate
Matthew R. BockmanVeronica V. Angeles Julia M. MartinoPurav P. Vagadia Ram S. Mohan 《Tetrahedron letters》2011,52(51):6939-6941
A mild method for the deprotection of THP ethers catalyzed by iron(III) tosylate (2.0 mol %) in CH3OH has been developed. Iron(III) tosylate, Fe(OTs)3·6H2O, is a commercially available solid that is inexpensive, noncorrosive, and easy to handle. The room temperature reaction conditions make this method attractive for deprotection of a range of THP ethers. 相似文献
394.
M. Angeles Alvarez Remedios Carreño Claudette Bois 《Journal of organometallic chemistry》2011,696(9):1736-1748
The dimanganese hydride complexes [Mn2(μ-H)2(CO)6(μ-L2)] [L2 = (EtO)2POP(OEt)2 (tedip), Ph2PCH2PPh2 (dppm)] react with primary and secondary silanes H2SiPhR (R = Ph, Me, H) to give the corresponding derivatives [Mn2(μ-H2SiPhR)(CO)6(μ-L2)] having a silane molecule displaying a relatively unusual μ-κ2:κ2 coordination mode (averaged values are ca. Mn-H = 1.59 Å, H-Si = 1.69 Å and Mn-Si = 2.381 Å, when R = Ph and L2 = tedip). These complexes display in solution cis and/or trans arrangement of the bridging silane relative to the diphosphorus ligands (and facial and/or meridional arrangements of the corresponding carbonyl ligands), depending on the bridging groups. The novel unsaturated dihydride [Mn2(μ-H)2(CO)6(μ-dmpm)] (dmpm = Me2PCH2PMe2) has been prepared through the reaction of [Mn2(μ-Cl)2(μ-dmpm)(CO)6] and 5 equiv of Li[BH2Me2] in tetrahydrofuran followed by addition of water. The dihydride complexes [Mn2(μ-H)2(CO)6(μ-L2)] (L2 = tedip, dppm, dmpm) react with HSnPh3 to give different mixtures of products strongly dependent on the particular reaction conditions. We have thus been able to isolate and characterize five new types of dimanganese-tin derivatives: [Mn2(μ-SnPh2)2(CO)6(μ-L2)], [Mn2(μ-H)(μ-Ph2SnO(H)SnPh2)(CO)6(μ-L2)] (average values are Mn-Sn = 2.54 Å, Sn-O = 2.11 Å, when L2 = tedip), [Mn2(μ-H)(μ-κ1:κ2-HSnPh2)(CO)6(μ-L2)], [Mn2(μ-H)(μ-κ1:κ1-O(H)SnPh2)(CO)6(μ-L2)], and [Mn2(μ-H)(SnPh3)(CO)7(μ-L2)] (Mn-Mn = 3.237(1) Å, Mn-Sn = 2.642(1) Å, when L2 = dppm). 相似文献
395.
Mezcua M Malato O Martinez-Uroz MA Lozano A Agüera A Fernández-Alba AR 《Journal of AOAC International》2011,94(6):1674-1684
An automatic screening method based on HPLC/time-of-flight (TOF)-MS (full scan) was used for the analysis of 103 non-European fruit and vegetable samples after extraction by the quick, easy, cheap, effective, rugged, and safe method. The screening method uses a database that includes 300 pesticides, their fragments, and isotopical signals (910 ions) that identified 210 pesticides in 78 positive samples, with the highest number of detection being nine pesticides/sample. The concentrations of 97 pesticides were <10 microg/kg, 53 were between 10 and 100 microg/kg, and 60 were at a concentration of >100 microg/kg. Several parameters of the automatic screening method were carefully studied to avoid false positives and negatives in the studied samples; these included peak filter (number of chromatographic peak counts) and search criteria (retention time and error window). These parameters were affected by differences in mass accuracy and sensitivity of the two HPLC/TOF-MS systems used with different resolution powers (15 000 and 7500), the capabilities of which for resolving the ions included in the database from the matrix ions were studied in four matrixes, viz., pepper, rice, garlic, and cauliflower. Both of these mass resolutions were found to be satisfactory to resolve interferences from the signals of interest in the studied matrixes. 相似文献
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