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991.
IntroductionThecomprehensivemathematicalmodeldevelopedinthefirstpartofthispaper[1]containsdozensofcoupledequationsthatformalargenonlinearequationsystem.Herewecombineanalyticalandnumericalmethodstosolveitanddiscussandanalyzesomeimportantproblemsinmicroc… 相似文献
992.
Isolation of Phosphate-Solubilizing Fungi from Phosphate Mines and Their Effect on Wheat Seedling Growth 总被引:1,自引:0,他引:1
Chunqiao Xiao Ruan Chi Huan He Guanzhou Qiu Dianzuo Wang Wenxue Zhang 《Applied biochemistry and biotechnology》2009,159(2):330-342
Three phosphate-solubilizing fungi, identified as Penicillium expansum, Mucor ramosissimus, and Candida krissii, were isolated from phosphate mines (Hubei, People’s Republic of China) and characterized. All the isolates demonstrated
diverse levels of phosphate-solubilizing capability in National Botanical Research Institute’s phosphate growth medium containing
rock phosphate as sole phosphate source. Acidification of culture medium seemed to be the main mechanism for rock phosphate
solubilization. Indeed, citric acid, oxalic acid, and gluconic acid were shown to be present in the culture medium inoculated
with these isolates. Moreover, the isolates produced acid and alkaline phosphatases in culture medium, which may also be helpful
for RP solubilization. A strong negative correlation between content of soluble phosphorus and pH (r = – 0.89; p < 0.01) in culture medium was observed in this study. All the isolates promoted growth, soil available phosphorus, phosphorus,
and nitrogen uptake of wheat seedling in field soil containing rock phosphate under pot culture conditions, thus demonstrating
the capability of these isolates to convert insoluble form of phosphorus into plant available form from rock phosphate, and
therefore hold great potential for development as biofertilizers to enhance soil fertility and promote plant growth. 相似文献
993.
By the comparison of the reaction products of gem-dihalocyclopropanes under various conditions, it is suggested that similar to the reactions with metals, the reactive radical intermediates which make the reaction results complicated are formed in the reactions of gem-dihalocyclopropanes with alkyl lithium. Studies on the competitions between ring opening and intramolecular C—H insertions of cyclopropylidenes generated by the reactions of gem-dihalocyclopropanes with metals and discussions on the reaction mechanism are also given in this paper. 相似文献
994.
995.
Three-dimensional (3D) excitation-emission matrix (EEM) fluorescence spectroscopy is applied to characterize the coal oil. The results show that the 3D fluorescence spectra of coal oil in aqueous solution mainly have one broad peak. This peak is identified at the excitation/emission wavelengths of 270/290 nm. The relation between the fluorescence intensity and the concentration of coal oil is also studied. When the concentration lies between 2 - 2000 ppm, the relation between the fluorescence intensity and the concentration of coal oil is well linear. The nature of solvents significantly affects the EEM fluorescence of coal oil. 相似文献
996.
997.
998.
Junhua Xiao Gu Yuarf Weiqiang Huang John H. K. Lum K‐L Daniel Lee Albert S. C. Chan 《中国化学会会志》2001,48(5):929-932
Two nitrated analogs of distamycin were synthesized by a novel haloform reaction and the DCC/HOBT coupling reaction in a convenient and effective way with out amino group protection. Our results have demonstrated that these polyamides show DNA cleaving activity under long UV (LUV 365 nm) irradiation. Furthermore, it is an unexpected discovery that these analogs can prevent DNA dam age under short UV (SUV 302 nm). 相似文献
999.
1000.
Chang‐Yin Li Lian‐Wen Qi Ping Li Xiao‐Dong Wen Yan‐Fei Zhu E‐Hu Liu Zhen Gong Xiao‐Lin Yang Mei‐Ting Ren Yan‐Jing Li Xiao‐Xiao Ge 《Rapid communications in mass spectrometry : RCM》2009,23(13):1977-1988
A method coupling liquid chromatography with electrospray ionization time‐of‐flight mass spectrometry (LC/ESI‐TOF/MS) has been developed for rapid and sensitive analysis of rat urinary metabolite profile of Danggui Buxue Tang (DBT), a well‐known Chinese herbal formula. After oral administration of DBT, urine samples were collected during 0–24 h, and then pretreated by solid‐phase extraction. A total of 68 compounds including 13 parent compounds and 55 metabolites were detected in the drug‐containing urines compared with blank urines. The total analytical time was less than 20 min. Metabolites of DBT were identified using dynamic adjustment of the fragmentor voltage to produce structure‐relevant fragment ions. By using this approach, the mass accuracy of precursor and fragment ions was typically within ±5 ppm of the theoretical values, and enabled the identification of 43 metabolites including 27 isoflavanoid and 16 phthalide metabolites. Our results indicated that glucuronidation and sulfation were the major metabolic pathways of isoflavonoids, while glutathione conjugation, glucuronidation and sulfation were the main metabolic pathways of phthalides. No saponin‐related metabolites were detected. The results of the present study provided important structural information relating to the metabolism of DBT. Furthermore, this work demonstrated the potential of the LC/ESI‐TOF/MS approach for identification of metabolites from Chinese herbal medicines in urine. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献