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111.
For large-volume stacking with the electroosmotic flow pump (LVSEP) in capillary electrophoresis of anionic analytes it is required that the electroosmotic mobility (EOM) should be smaller than the magnitudes of the effective mobilities of the analytes. When a fused-silica capillary is treated with an acidic solution, the silanoate group on the silica surface is neutralized to silanol and the EOM is suppressed. Due to the slow deprotonation equilibrium of the silanol group at an intermediate pH, this reduced EOM can be retained during a number of electrophoresis runs. Using a bare fused-silica capillary preconditioned with 0.01 M HCl, successful LVSEP at pH 6.0 was achieved for weakly acidic compounds with two orders of magnitude enhancements in the concentration sensitivity. The repeatability in migration times of ten analytes stacked by LVSEP in a single day was excellent with the relative standard deviation (RSD) less than 1% (n = 6). The day-to-day repeatability was also excellent with RSD less than 3% (n = 3 x 6) when the capillary was preconditioned each day. 相似文献
112.
PU大分子单体水溶液性质 总被引:2,自引:0,他引:2
双亲聚合物一般由亲水和亲油 2种链段构成 ,有嵌段型[1,2 ] 和接枝型[3 ] 2种 ,其中通过大分子单体法合成双亲接枝聚合物备受关注[4] 。如以亲水性大分子单体和亲油性小分子单体共聚 ,大分子单体构成共聚物主链上支链 ,具有较大活动性 ,亲水效能高。采用对氯甲基苯乙烯[5] 或甲基丙烯酰氯[6] 与聚氧化乙烯大分子的一端相反应 ,可得到亲水性大分子单体 ,但其分子量及结构变化有限。本文采用常规条件 ,合成了嵌段式水溶性聚氨酯大分子单体 ,其分子量较大 ,共聚接枝的支链较长。利用该大分子单体具有非离子高分子表面活性剂的性质 ,采用无皂乳… 相似文献
113.
114.
烯丙位氧化的几种方法 总被引:4,自引:0,他引:4
综述了近年来烯丙位氧化的研究进展,详细讨论了过渡金属及其络合物、硒化 合物在烯丙位氧化中的应用,并简述了丁基锂方法、固相催化方法、生物氧化方法 和次氯酸钠氧化方法在烯丙位氧化中的应用. 相似文献
115.
Jung-Ah Kang Ji-Sun Kwak Sang-Heon Park Kyu-Young Sim Seul Ki Kim Youngnim Shin In Jung Jung Jeong-In Yang Jang-Soo Chun Sung-Gyoo Park 《Experimental & molecular medicine》2021,53(4):560
Zinc is a trace element that is essential for immune responses. Therefore, changes in cellular zinc levels in specific immune cells may influence inflammatory autoimmune diseases, such as rheumatoid arthritis (RA). However, the regulation of zinc mobilization in immune cells and its role in the pathogenesis of RA are not fully understood. Thus, we investigated the roles of zinc transporters in RA pathogenesis. We demonstrated that ZIP8 was specifically upregulated in CD4+ T cells that infiltrated the inflamed joint and that ZIP8 deficiency in CD4+ T cells abrogated collagen-induced arthritis. ZIP8 deficiency dramatically affected zinc influx in effector T cells and profoundly reduced T cell receptor (TCR)-mediated signaling, including NF-κB and MAPK signaling, which are pathways that are involved in T helper (Th) 17 cell differentiation. Taken together, our findings suggest that ZIP8 depletion in CD4+ T cells attenuates TCR signaling due to insufficient cellular zinc, thereby reducing the function of effector CD4+ T cells, including Th17 cells. Our results also suggest that targeting ZIP8 may be a useful strategy to inhibit RA development and pathogenesis.Subject terms: Autoimmunity, Immunological disorders 相似文献
116.
Xin Sheng Li Yan Xin Chen Yao Jun Zhang Chun Xin Ji Qin Xin 《Reaction Kinetics and Catalysis Letters》1996,58(2):391-396
Hydrogen adsorption-desorption over Mo2N has been studied using a temperature-programmed technique. It is revealed that hydrogen on Mo2N exhibits very high mobility leading to migration of the surface hydrogen into the sublayer and bulk of the sample or the reverse. The surface hydrogen species are preferentially formed when adsorption is carried out below 573 K. On increasing the adsorption temperature to above 573 K, the quantity of hydrogen species located in the sublayer or/and bulk of the Mo2N sample increases significantly. 相似文献
117.
新型含氟聚芳醚酮的合成与表征 总被引:10,自引:0,他引:10
聚芳醚酮具有很高的热稳定性和优良的电性能及机械性能 ,已经被广泛应用于宇航、电子及核能等高技术领域 [1] .氟元素的引入可以降低材料介电常数、折光指数和吸水率 ,提高热稳定性、溶解性和阻燃性 ,增加材料透明度 ,使这类聚合物在光电子、光学和微电子等应用领域的研究倍受关注 [2~ 4 ] .本文在合成含三氟甲基苯侧基的聚芳醚酮 [5] 的基础上 ,设计并合成了新型的含氟量更高的单体和聚合物 ,并对其性能进行了初步研究 .1 实验部分1 .1 试剂与仪器 [3,5 -二 (三氟甲基 ) ]苯代对苯醌 (自制 ) ;锌粉 ,A.R.级 ,天津化学试剂一厂产品 ;… 相似文献
118.
In the presence of copper(I) iodide as catalyst, a variety of carbonyl compounds, such as aldehydes, ketones and acid anhydrous, could be trifluoromethylated with sodium trifluoroacetate to give the corresponding alcohols in moderate to high yields, and a possible mechanism was proposed to explain the roles of catalyst and solvent in the reaction system. 相似文献
119.
Howard C. Clark Anil B. Goel Chun S. Wong 《Journal of organometallic chemistry》1980,190(4):C101-C104
Simple synthetic routes to the mixed ligand complexes PtLL'X2 and PtLL'XY (L' = PEt3; L = phosphine, arsine, etc.; X = Cl and Y = Cl, H or Me) are described; unexpectedly, these display an extensive chemistry without disproportionation, although in some cases ligand scrambling does occur. 相似文献
120.