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181.
Reactions of ketenes generated from alpha-diazoketones with a series of acyclic and cyclic imines were investigated under both microwave and photoirradiation conditions. The results indicate that the zwitterionic azabutadiene-type intermediates yielded from imines and ketenes undergo a conrotatory ring closure exclusively to produce beta-lactams. It is notable that no Woodward-Hoffmann product was found under the ultraviolet irradiation. The photoirradiation-induced Staudinger reaction shows a different stereoselectivity from the electrocyclic reaction of substituted 1,3-butadiene. 相似文献
182.
M. G. Fan Y. C. Liang Y. F. Ming J. X. Chen T. Ye Q. Y. Zhang B. A. Xu S. Jin 《Research on Chemical Intermediates》1998,24(9):961-971
Photophysical behavior of spiro[1,3,3-trimethylindolino-2,3′-naphtho[2,1-b]-1,4-oxazine] (SP1) and spiro[1,3,3,2′-tetramethylindolino-2,3′-naphtho[2,1-b]-1,4-oxazine] (SP2) were studied. The fluorescent species and their spectra of SP1 and SP2 in polar solvents (acetonitrile and methanol) and non-polar solvent (cyclohexane) were investigated. The fluorescence decay
in polar solvents was studied by picosecond time-correlated single photon counting. In most cases, fluorescence decay obeyed
triexponential decay kinetics. The major fluorescent species is an excited intermediate which has similar conformation as
its precursor (1
SP
*) formed after the bond cleavage between spirocarbon and oxygen in oxazine ring. The effects of molecular structure and solvent
polarity on fluorescence spectra and fluorescence decay lifetime were studied. 相似文献
183.
Li Yan Liang Shao Ping Ren Yi Quan Zheng Man Geng Lu Guangzhou Institute of Chemistry Chinese Academy of Sciences Guangzhou China Key Laboratory of Polymer Materials for Electronics Guangdong China Graduate School of the Chinese Academy of Sciences Beijing China 《中国化学快报》2007,18(2):225-228
A series of novel liquid crystalline epoxides with lateral substituents were cured with anhydrides and the cure kinetics was investigated by non-isothermal DSC technique. The results showed that the lengths of lateral substituents have great effect on the value of Ea. The curing reaction became less active, when the liquid crystalline epoxides have long lateral substituents and were controlled by diffusion at the late stage of cure. A nematic structure was observed by POM and XRD. 相似文献
184.
L. N. Yang S. J. Qiu F. Xu L. X. Sun Z. B. Zhao J. G. Liang C. G. Song 《Journal of Thermal Analysis and Calorimetry》2007,89(3):875-879
The effects of Amoxicillin Sodium and Cefuroxime Sodium on the growth of E. coli DH5α were investigated by microcalorimetry. The metabolic power-time curves of E. coli DH5α growth were determined by using a TAM air isothermal microcalorimeter at 37°C. By evaluation of the obtained parameters,
such as growth rate constants (k), inhibitory ratio (I), the maximum heat power (P
m) and the time of the maximum heat power (t
m), one found that the inhibitory activity of Amoxicillin Sodium vs. E. coli DH5α is enhanced with the increasing of the Amoxicillin Sodium concentration, and the Cefuroxime Sodium has a stimulatory effect on the E. coli DH5α growth when the concentration is about 1 μg mL−1. The IC50 for the Amoxicillin Sodium and the Cefuroxime Sodium are 1.6 and 2.0 μg mL−1, respectively, it implicates that the E. coli DH5α is more sensitive to Amoxicillin Sodium than Cefuroxime Sodium. 相似文献
185.
Wen-Jia Zhou Shu-Juan Bao Yan-Yu Liang Ben-Lin He Hu-Lin Li 《Journal of Solid State Electrochemistry》2006,10(5):277-282
Pure-phase and well-crystallized spinel LiMn2O4 powders were successfully synthesized by a simple rheological phase method. The thermal behavior and structure properties
of the powders prepared by the rheological phase method compared with the solid-state reaction were investigated by thermogravimetry,
powder X-ray diffraction , scanning electron microscopy and transmission electron microscopy. According to the results of
the electrochemical tests, it is obvious that the sample resulting from the rheological phase method shows higher discharge
capacity and better cycling stability than one formed in the solid-state reaction. The cyclic voltammogram and columbic efficiency
curves also confirm that the product by the rheological phase method has a good cycling performance due to its fine cubic
spinel structure and morphology. 相似文献
186.
QiLiangDENG ZhiHongLUN ChaoYAN RuYuGAO 《中国化学快报》2005,16(7):955-958
This study concentrated on the production of molecularly imprinted polymers (MIPs) as highly selective sorbents for felodipine (FLD), a representive dihydropyridine calcium antagonists. Demonstrated chromatographically through a selection factor, these MIPs showed high selectivity for the template molecule among a group of structurally similar compounds. The recognition was found to correlate with structural similarity to the template compound. 相似文献
187.
Qing-shan Liang Jian-Gang Xie ChaoPing Yu ZhuSheng Feng JingChang Ma Yuan Zhang Dong Wang JianGuo Lu Ran Zhuang Jikai Yin 《Experimental & molecular medicine》2021,53(3):393
Splenectomy has been reported to improve liver fibrosis in patients with cirrhosis and hypersplenism. However, the mechanisms remain unclear. Tumor necrosis factor superfamily 14 (TNFSF14; also known as LIGHT) is highly expressed in the context of fibrosis and promotes disease progression in patients with fibrotic diseases such as pulmonary and skin fibrosis. Here, we determined whether splenectomy controls the production of LIGHT to improve liver fibrosis. Splenectomy reduced serum LIGHT levels in cirrhotic patients with hypersplenism and a ConA-induced liver fibrosis mouse model. Blocking LIGHT resulted in the downregulation of TGF-β1 in RAW264.7 cells. LIGHT treatment of RAW264.7 and JS1 cells in coculture regulated transforming growth factor-β1 (TGF-β1) expression through the activation of JNK signaling. Small interfering RNA-mediated silencing of lymphotoxin β receptor (LTβR) in macrophages resulted in pronounced decreases in the levels of fibrosis and αSMA in JS1 cells. These results indicated that LIGHT bound to LTβR and drove liver fibrosis in vitro. Blocking TGF-β1 abolished the effect of LIGHT in vitro. Furthermore, the administration of recombinant murine LIGHT protein-induced liver fibrosis with splenectomy, while blocking LIGHT without splenectomy improved liver fibrosis in vivo, revealing that the decrease in fibrosis following splenectomy was directly related to reduced levels of LIGHT. Thus, high levels of LIGHT derived from the spleen and hepatic macrophages activate JNK signaling and lead to increased TGF-β1 production in hepatic macrophages. Splenectomy attenuates liver fibrosis by decreasing the expression of LIGHT.Subject terms: Tumour-necrosis factors, Liver fibrosis, Hepatic stellate cells, Liver cirrhosis, Experimental models of disease 相似文献
188.
A bio-mimic bulk acoustic wave (BAW) sensor was fabricated by coating the caffeine (CAF) template molecular imprinting polymer (MIP). This sensor exhibited high selectivity and a sensitive mass response to CAF. The response range of the sensor was between 5.0 x 10(-9) and 1.0 x 10(-4) M with a detection limit of 5.0 x 10(-9) M at pH 8.0. Recoveries were 96.1-105.6%. Influencing factors were investigated in detail and optimized. When employed to detect real samples, the proposed method proved to be a convenient method with the advantages of high sensitivity, good selectivity and ease of handling. 相似文献
189.
锌(Ⅱ)与N-苯甲酰苯丙氨酸及二胺类混配配合物的合成与表征*沈良(杭州师范学院化学系杭州310012)龚钰秋(杭州大学化学系杭州310028)关键词锌(Ⅱ)N-苯甲酰苯丙氨酸二胺混配配合物合成中图分类号O629.7含有末端N-乙酰及N-苯甲酰残基的氨... 相似文献
190.
Daniel R. Coulter Ranty H. Liang Salvador Di Stefano Jovan Moacanin Amitava Gupta 《Chemical physics letters》1982,87(6):594-598
Transient emission studies following pulse radiolysis of solid poly(1-vinyl naphthalene) show existence of excited monomers and two excimers. Quenching experiments indicate that excimers are not formed directly by recombination of ions but probably by trapping of migrating monomeric excitation in performed traps whose density is approximately one in 103. 相似文献