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81.
XinMeiZHENG YanXingQI XiaoMingZHANG JiShuanSUO 《中国化学快报》2004,15(6):655-658
Jacobsen‘s catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times. 相似文献
82.
83.
The fluorescent calcium ion indicator dye Fluo-3 and DNA-binding dye Hoechst 33342 were employed to determine, in a quantitative microspectrofluorometric study, the intracellular calcium ion concentration ([Ca~(2+)]_i) and the DNA content of individual living NIH3T3 cells. The well-separated excitation and emission properties of these dyes allowed us to establish for each cell both the phase of the cell cycle using DNA content and [Ca~(2+)]_i. We found that the transition from G_1, through S, to the G_2 phase is accompanied by a two-fold increase in [Ca~(2+)]_i. The [Ca~(2+)]_i was inhomologous in each phase of the interphase (G_1, S and G_2) although [Ca~(2+)]_i in the S and G_2 phases was never lower than certain threshold values in the G_1 and S phases respectively. [Ca~(2+)]_i in G_0 cells was lower than that in G_2 cells. These changes in [Ca~(2+)]_i suggest that [Ca~(2+)]_i may be an import regulator of cell cycle progression. 相似文献
84.
集化学家与化学教育家于一身的一代化学大师李比希--纪念李比希诞辰200周年 总被引:1,自引:0,他引:1
在德国著名化学家李比希诞辰200周年之际,对这位集化学家与化学教育家于一身的一代化学大师对科学和科学教育以及人类社会作出的贡献进行了评述。 相似文献
85.
A nondestructive desulfurization microorganism has been isolated. The metabolism product analyses show that the strain can be a kind of biocatalyst to oxidize dibenzothiophene (DBT) into 2-hydroxydiphenyl (HBP), therefore the sulfur in DBT is removed selectively. The 16SrRNA information, cell wall analysis, physical, biochemical properties and morphological properties suggest that the isolated strain is Rhodococcus erythropolis. The strain can grow in the basal salts medium (BSM) that DBT concentration is no more than 10 mmol/L, and the optimal DBT concentration for growth is 1 mmol/L, however, the optimal DBT concentration for desulfurization is 0.5 mmol/L. The further research shows that the strain can also desulfur some other or-ganosulfur-containing compounds such as thianaphthene, phenyl sulfide and 4,6-dimethyldiben-zothiophene (4,6-DMDBT). 相似文献
86.
甲基丙烯酸-N,N-二甲氨基乙酯及其聚合物的热和pH响应性 总被引:2,自引:2,他引:2
Dimethylaminocthyl methylacrylate (DMAEMA) and its polymer exhibit thermo-sensitive response. The phase separation of their aqueous solution occurs abfruptly when the raising temperature reachs certain degrees. Thus, the temperature of phase separation of 10%,5.0%,2.5%,1.0%(DMAEMA) solution are 40.2,42.5,44.5,52.4℃ respectively. The thermosensitive phase separation also depends on the acidity of solution. The temperature and pH dependence swelling behavior o f slightly crosslinked P(DMAEMA) in water was studied. The adsorption of met-hyl orange for P(DMAEMA) at different temperature was investigated. P(DMAEMA) can he expected as a functional material with thermal and pH-response. 相似文献
87.
本文报道了一种新的配体:10-乙基-3-甲酰吩噻嗪缩肼基二硫代甲酸甲酯(HL)及其金属配合物的合成。采用了元素分析、质谱、核磁共振、红外光谱对配体及其金属配合物进行了表征。此外,并应用紫外、荧光和Z-扫描技术,测定了配体及其金属配合物的荧光最佳发射波长(λmaxem)、荧光量子产率(Φf)、寿命(τ)和非线性光学性质。结果表明它们在DMF溶液中都能发射出较强的橄榄色荧光,配体及其金属配合物都有双光子吸收,并且金属配合物的非线性光学效应比配体明显增强。用半经验量子化学方法(RHF/PM3)计算结果与实验值较为吻合。 相似文献
88.
Jun Zhang Kaimin Liu Gengmei Xing Tongxiang Ren Shukuan Wang 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(3):605-609
Gd@C82(OH)40 has been developed as a new generation of MRI contrast agent. But recently, it was found that Gd@C82(OH)
x
with a larger number of OH (x>36) would lead to cage break and hence, release of highly toxic Gd ions. We synthesized the more stable Gd@C82(OH)
x
with less OH-number, Gd@C82(OH)16, and studied its proton relaxivity and MRI images. The results indicate that Gd@C82(OH)16 also gives high proton relaxivity, even higher than that of (NMG)2-Gd-DTPA. The bio-distribution indicated that Gd@C82(OH)16 tends to be entrapped in the liver and kidney and remained in tissue for about 2 hours. The results suggest that the more
stable metallofullerene derivative Gd@C82(OH)16 can be the potential candidate of the new MRI contrast agent. 相似文献
89.
GC-MS法测定拟除虫菊酯类农药残留 总被引:3,自引:0,他引:3
介绍了蔬菜水果中8种拟除虫菊酯农药残留的快速检测方法。采用选择离子-气相色谱-质谱联用(SIM-GC-MS)方式,依据保留时间和特征离子丰度比对农药进行确证。此方法可以在13.50 min内快速检测拟除虫菊酯农药残留,并可同时定性和定量,用于蔬菜水果等多种作物的检验。回收率在75%~108%间,相对标准偏差<10%,检出限为0.000 90~0.008 4 mg.kg-1。 相似文献
90.