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21.
Shujiang Tu Fang Fang Songlei Zhu Tuanjie Li Xiaojing Zhang Qiya Zhuang Shuijun Ji Yong Zhang 《Journal of heterocyclic chemistry》2005,42(1):29-32
The synthesis of bifunctional pyridine and quinolione derivatives were investigated using terephthalic and isophthalic aldehydes as a precursor. The reaction proceeds under microwave irradiation with good yield (70–92%) and short reaction time (7–9 min.). We provide a rapid and efficient method of synthesizing a range of bifunctional monocyclic and bicyclic products related to 1,4‐dihydropyridines (1,4‐DHPs). 相似文献
22.
The flocculation between the rod-like biopolymer Schizophyllan and two types of colloidal particles (latex with diameter 40 nm and alumina with diameter 60 nm) has been investigated by means of fluorescence correlation spectroscopy (FCS). The concentration ratio of Schizophyllan/particle q was varied in the range 0.1 approximately 20. Under conditions of pH about 5.7, 1 mmol.L(-1) NaCl, and room temperature (22+/-0.5 degrees C), the particles are strongly charged (alumina particles positively charged, latex negatively), while Schizophyllan is neutral. We observed that Schizophyllan chains flocculate with both types of particles, which suggests that the charge neutralization does not play a decisive role in these interactions. The ratio of fluorescence intensity of one floc over that of one particle, Q(f)/Q(p), and the corresponding hydrodynamic radius (r(h)) of the flocs have been measured. For a Schizophyllan-latex system, Q(f)/Q(p) reached a maximum value of 5 for q=3 indicating that the flocs contained five particles on average. The corresponding value of r(h) was r(h)=455 nm. The flocculation kinetic of latex particles with Schizophyllan was too fast to be measurable by FCS. For the Schizophyllan-alumina system, Q(f)/Q(p) was stable at about 1 in the whole studied range of q but r(h) increased with q suggesting that many Schizophyllan chains are adsorbed on individual particles. The flocculation kinetic of this system was studied by FCS and the obtained results were compatible with those of photon correlation spectroscopy. 相似文献
23.
Mathematical Notes - The Boros–Moll polynomials $$P_m(a)$$ arise in the evaluation of a quartic integral. In the past few years, there has been some remarkable research on the properties of... 相似文献
24.
Xiaojing Xiang 《Annals of the Institute of Statistical Mathematics》1995,47(1):105-117
A necessary condition for the asymptotic normality of the sample quantile estimator isf(Q(p))=F(Q(p))>0, whereQ(p) is thep-th quantile of the distribution functionF(x). In this paper, we estimate a quantile by a kernel quantile estimator when this condition is violated. We have shown that the kernel quantile estimator is asymptotically normal in some nonstandard cases. The optimal convergence rate of the mean squared error for the kernel estimator is obtained with respect to the asymptotically optimal bandwidth. A law of the iterated logarithm is also established.This research was partially supported by the new faculty award from the University of Oregon. 相似文献
25.
哺乳动物体内氨基酸及蛋白质的非酶糖化反应(Mailard反应)与糖尿病及其并发症的关系已引起广泛关注[1],β-羧乙基锗倍半氧化物(Ge-132)具有预防糖尿病和调节糖代谢的作用[2],研究Ge-132对Mailard反应的抑制作用对于开发防治糖尿病... 相似文献
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Bixing Fang Lina Dong Xingwei Ding YingZi Ren Zhongsheng Lv Kuan Liu Feng Zhang Wei Zhang Jianjian Deng Hongbo Xin Xiaolei Wang 《中国化学快报》2019,30(6):1178-1181
Black fungus aerogel (BFA) exhibited interesting double-faced properties. Weexplored the diverse properties of each side of the black fungus in three aspects:water contact angle measurements, liquid selective absorption capacity and air pollutant adsorption abilities. 相似文献
29.
Renqing Lü 《天然气化学杂志》2005,14(2):119-124
The density functional theory and the cluster model methods have been employed to investigate the interactions between ethanethiol and HZSM-5 zeolites. Molecular complexes formed by the adsorption of ethanethiol on silanol H3SiOH with two coordination forms, model Bronsted acid sites of zeolite cluster H3Si(OH)Al(OH)2SiH3 interaction with ethanethiol, aluminum species adsorbed ethanethiol have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using B3LYP hybrid method at 3-21G basis level for hydrogen atoms and 6-31G(d) basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms of H3Si(OH)Al(OH)2SiH3-ethanethiol, silanol-ethanethiol and Al(OH)3-ethanethiol have been studied. The calculated results showed the nature of interactions was van der Waals force as exhibited by not much change in geometric structures and properties. The preference order of ethanethiol adsorbed on HZSM-5 zeolite may be residual aluminum species, bridging hydroxyl groups and silanol OH groups from the adsorption heat. The adsorbed models of protonized ethanethiol on bridging hydroxyl OH groups and linear hydrogen bonded ethanethiol on bridging OH groups suggested in literature might not exist as revealed by this theoretical calculation. Possible adsorption models were obtained for the first time. 相似文献
30.
A room-temperature ionic liquid (IL), 1-ethyl-3-methyl-imidazolium tetrafluoroborate (1E-3MI-TFB), used for the coating of
a silica capillary enables one to reduce or invert the electroosmotic flow (EOF) in capillary zone electrophoresis. Excellent
separations of amino acids and ary lalkanoic acids were obtained. Such separations could not be obtained in a naked capillary
in the presence of the cationic surfactants cetyltrimethylammonium bromide (CTAB) or polycationic polymer hexadimethrine bromide
(HDB). The results indicate that 1E-3MI-TFB not only modulates the EOF but also acts as a discriminator. Further experiments
indicate that the interaction between hydrogen at C-2 carbon of IL and acid drugs plays an important role in the separation.
The text was submitted by the authors in English. 相似文献