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排序方式: 共有288条查询结果,搜索用时 375 毫秒
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Alexopoulos T Allen C Anderson EW Areti H Banerjee S Beery PD Biswas NN Bujak A Carmony DD Carter T Cole P Choi Y De Bonte RJ Erwin AR Findeisen C Goshaw AT Gutay LJ Hirsch AS Hojvat C Kenney VP Lindsey CS LoSecco JM McMahon T McManus AP Morgan N Nelson KS Oh SH Piekarz J Porile NT Reeves D Scharenberg RP Stampke SR Stringfellow BC Thompson MA Turkot F Walker WD Wang CH Wesson DK 《Physical review letters》1990,64(9):991-994
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(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺反相微乳液共聚合研究 总被引:14,自引:0,他引:14
采用SPAN-OP复合乳化剂和K_2S_2O_8-Na_2SO_3氧化还原引发剂,进行(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺的反相微乳液共聚合。测得单体的竞聚率r_(DM·MC)=1.11±0.16,r_(AM)=0.53±0.08。在单体总浓度为20—40%(wt),引发剂浓度为0.01—0.05%,乳化剂浓度为10—18%,聚合温度为299K的条件下,得到共聚反应动力学方程:R_p=k[M]~(1.07)[I]~(0.52)[E]~(0.90),文中对上述结果做了解释。 相似文献
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Alexopoulos T Allen C Anderson EW Balamurali V Banerjee S Beery PD Bhat P Bishop JM Biswas NN Bujak A Carmony DD Carter T Choi Y Cole P DeBonte R DeCarlo V Erwin AR Findeisen C Goshaw AT Gutay LJ Hirsch AS Hojvat C Jennings JR Kenney VP Lindsey CS Loomis C LoSecco JM McMahon T McManus AP Morgan N Nelson K Oh SH Porile NT Reeves D Rimai A Robertson WJ Scharenberg RP Stampke SR Stringfellow BC Thompson M Turkot F Walker WD Wang CH Warchol J Wesson DK Zhan Y 《Physical review D: Particles and fields》1993,48(3):984-997
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K T McManus J D deBethizy D A Garteiz G A Kyerematen E S Vesell 《Journal of chromatographic science》1990,28(10):510-516
A rapid thermospray liquid chromatography-mass spectrometry (TSP LC-MS) method is described for the simultaneous determination of nicotine and 17 of its metabolites. Chemical ionization of nicotine and its metabolites separated by reversed-phase HPLC is achieved by postcolumn addition of ammonium acetate buffer with the filament of the ion source turned off. Quantification is accomplished by selectively monitoring the unique protonated molecular ion of each metabolite. Trideuterated cotinine serves as an internal standard. Linear responses for cotinine, demethylcotinine, and trans-3'-hydroxycotinine were observed over a concentration range of 20-8000 ng/mL, and 80-8000 ng/ml for nicotine and nicotine-1'-N-oxide. Of the 17 metabolites examined, only nicotine, cotinine, demethylcotinine, and trans-3'-hydroxycotinine were detected in smokers' urine. 相似文献
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Alberola A Farley RD Humphrey SM McManus GD Murphy DM Rawson JM 《Dalton transactions (Cambridge, England : 2003)》2005,(24):3838-3845
Selective chlorination of thiophene-2,3-dithiol with SO(2)Cl(2) generates the corresponding sulfenyl chloride, 2,3-C(4)H(2)S(SCl)(2). Subsequent condensation with Me(3)SiN(3) yields the thiophenodithiazolylium salt [C(4)H(2)S(3)N]Cl, [TDTA]Cl. The structure of the cation, TDTA+, was established by X-ray diffraction as both its AsF(6)(-) and HSO(4)(-) salts. Reduction of [TDTA]Cl with Ag powder yields the radical TDTA* which was characterised by X- and Q-band (9 and 34 GHz) EPR and ENDOR studies. The spin density distributions estimated from the EPR/ENDOR measurements were found to be in very good agreement with those determined by DFT (B3LYP/6-31G*) indicating that ca 10% of the spin density is delocalised onto the thiophene ring. Comparison of the spin density distributions in TDTA* and the isoelectronic trithiatriazapentalenyl radical C(2)S(3)N(3), TTTA*, indicates that replacement of N by C-H leads to a localisation of the spin density on the dithiazolyl ring. 相似文献
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In the presence of calcium, DNA and unilamellar liposomes of the zwitterionic lipid DPPC form a complex in which DNA strands are embedded between a lamellar phase of DPPC. In some complexes, in-plane alignment of the DNA strands occurs, where a DNA-DNA interaxial distance can be measured using small-angle X-ray scattering. Here we report a higher level of DNA organization, with a rectangular columnar phase of DNA identified within this complex structure. This observation is important in view of recent interests in creating new synthetic systems at the interface of biology. 相似文献
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C. Allen Chang Tamar E. Woodhouse Qihui Wu Ceshing Sheu Katherine McManus 《中国化学会会志》1988,35(4):253-260
Substitution-inert metal complexes, [Co(edda)(H2O)2]+, (Co(edda)(en)]+, [Co(edda)(dmen)]+, [Co(en)2-(gly)]2+, [Co(en)2(acac)]2+, and [Co(trien)(gly)]2+ in their nitrate salt solutions are used as eluents in nonsuppressed cation chromatography (where edda = ethylenediamine-N,N′-diacetic acid, en = ethylenediamine, dmen = N,N′-dime-thylethylenediamine, gly = glycine, acac = acetylacetone, and trien = triethylenetetraamine). It is found that all the mono- and di-valent charged complexes can be used to separate alkali and alkaline earth metal cations, respectively. The separations for monovalent cations are sometimes comparable to those using ultrapure HNO3 solutions. However, the divalent Ca2+ and Sr2+ ions cannot be resolved using the metal complex eluents. On the other hand, a selected, direct non-suppressed IC separation of zinc(II) and cadmium(II) ions is demonstrated for the first time using a substitution-inert metal complex eluent and a conductivity detector. Comparisons of these eluents with those reported previously, i. e. HNO3 and ethylenediammonium salt solution are made and explanations are proposed to account for the different selectivities observed where possible. The future development of this technique is also briefly discussed. 相似文献