检索结果-南通市图书馆

Kinetic study on hydrolysis and oxidation of formamidine disulfide in acidic solutions

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2012年第2期55卷 235-241页

作者： HU ying feng JiaMin li YanWei SUN YanYan XU li ZHAO YueMin GAO QingYu College of Chemical Engineering China University of Mining and Technology Xuzhou 221008 China

Hydrolysis and oxidation of formamidine disulfide in acidic medium were investigated using high-performance liquid chro- matography （HPLC） and mass spectrometry （MS） at 25 ~C. By controlling the slow reaction rate and choosing appropriate mobile phase, HPLC provides the unique advantages over other methods （UV-Vis, chemical separation） in species tracking and kinetic study. In addition to thiourea and formamidine sulfinic acid, two unreported products were also detected in the hy- drolysis reaction. Mass spectrometry measurement indicates these two products to be formamidine sulfenic acid and thiocyan- ogen with mass weights of 92.28 and 116,36, respectively. In the oxidation of formamidine disulfide by hydrogen peroxide, besides thiourea, formamidine sulfenic acid, formamidine sulfinic acid, thiocyanogen and urea, formamidine sulfonic acid and sulfate could be detected. The oxidation reaction was found to be first order in both forrnamidine disulfide and hydrogen per- oxide. The rate constants of hydrolysis and oxidation reactions were determined in the pH range of 1.5-3.0. It was found both rate constants are increased with the increasing of pH. Experimental curves of different species can be effectively simulated via a mechanism scheme for formamidine disulfide oxidation, including hydrolysis equilibrium of formamidine disulfide and irre- versible hydrolysis of formamidine sulfenic acid.

关键词： formamidine disulfide hydrolysis oxidation HPLC-MS

Analysis of both chitinase and chitosanase produced by Sphingomonas ***-5

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2007年第11期8卷 831-838页

作者： ZHU Xu-fen ZHOU ying feng Jun-li College of life Science Zhejiang University Hangzhou 310058 China

A novel chitinolytic and chitosanolytic bacterium, Sphingomonas sp. CJ-5, has been isolated and characterized. It secretes both chitinase and chitosanase into surrounding medium in response to chitin or chitosan induction. To characterize the enzymes, both chitinase and chitosanase were purified by ammonium sulfate precipitation, Sephadex G-200 gel filtration and DEAE-Sepharose Fast Flow. SDS-PAGE analysis demonstrated molecular masses of chitinase and chitosanase were 230 kDa and 45 kDa respectively. The optimum hydrolysis conditions for chitinase were about pH 7.0 and 36 ℃, and these for chitosanase were pH 6.5 and 56 ℃, respectively. Both enzymes were quite stable up to 45 ℃ for one hour at pH 5-8. These results show that CJ-5 may have potential for industrial application particularly in recycling of chitin wastes.

关键词： Sphingomonas sp. Chitinase Chitosanase

Positive Shifts of the Reduction Potentials of C_(60) by Substitution of Cyanogens

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1998年第1期9卷 99-101页

作者： Lou Zhen FAN Yong Fang li feng ying li Yu liang li Dao Ben ZHU(Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080) Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

The electrochemical properties of a new derivative of C60 were investigated by cyclic voltammetry. It was found that the derivative was reduced at a more positive potential than C60,reflecting its significance to acce... 详细信息

关键词： C_(60) derivative electrochemical properties NIR absorption bands

In vitro cultivation and differentiation of fetal liver stem cells from mice

在线全文

学校读者我要写书评

暂无评论

Cell Research 2005年第5期15卷 401-405页

作者： Ren Qing feng*, li ying DU, Zhen Quan GUO College of life Sciences, Peking University, Beijing 100871, China College of life Sciences Peking University Beijing China

During embryonic development, pluripotent endoderm tissue in the developing foregut may adopt pancreatic fate or hepatic fate depending on the activation of key developmental regulators. Transdifferentiation occurs between hepato- cytes and pancreatic cells under specific conditions. Hepatocytes and pancreatic cells have the common endodermal progenitor cells. In this study we isolated hepatic stem/progenitor cells from embryonic day (ED) 12-14 Kun-Ming mice with fluorescence-activated cell sorting (FACS). The cells were cultured under specific conditions. The cultured cells deploy dithizone staining and immunocytochemical staining at the 15th, 30th and 40th day after isolation. The results indicated the presence of insulin-producing cells. When the insulin-producing cells were transplanted into alloxan- induced diabetic mice, the nonfasting blood glucose level was reduced. These results suggested that fetal liver stem/ progenitor cells could be converted into insulin-producing cells under specific culture conditions. Fetal liver stem/ progenitor cells could become the potential source of insulin-producing cells for successful cell transplantation therapy strategies of diabetes.

关键词： Hepatic stem/progenitor cell diabetes β-cell dithizone staining immunocytochemistry.

Effect of Micro-Area pH Value on Formation of Different Rust Phases of Weathering Steel in Initial Corrosion Period

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2010年第9期17卷 69-72,78页

作者： CHEN Xiao-ping WANG Xiang-dong liU Qing-you MI feng-yi CHEN ying li Yu-su Central Iron and Steel Research Institute Beijing 100081 China

The formation of protective rust layer of atmospheric corrosion resistance was discussed for weathering steel. The rust layers of experimental steels were made by using an accelerating industrial atmospheric corrosion test of dry-wet cyclic immersion. Furthermore XRD were used to measure and analyze the rust layers. The initial corrosion processes below thin water film were observed and the changes of micro-area pH value were measured. The results are as follows： The corrosion processes of P-RE weathering steel are obviously different from those of carbon steel. The surface of P-RE weathering steel rapidly forms a-FeOOH and the micro-area pH value is above 5.4 during the initial corrosion period. While the component of the rust layer for the carbon steel is mainly Fe3O4 and the microarea pH value is below 3.8.

关键词： weathering steel pH value micro area rust phase

RegIV expression showing specificity to gastrointestinal tract and its potential role in diagnosing digestive tract neuroendocrine tumor

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第4期11卷 258-266页

作者： feng-ying li Xiao-bin REN En-ping XU Qiong HUANG Hong-qiang SHENG Bing-jian LV Mao-de LAI Department of Pathology School of Medicine Zhejiang University Hangzhou 310058 China Clinical Laboratory Sir Run Run Shaw Hospital School of Medicine Zhejiang University Hangzhou 310016 China Department of Epidemiology and Biostatistics School of Medicine Zhejiang University Hangzhou 310058 China Anatomical and Cellular Pathology Women 's Hospital School of Medicine Zhejiang University Hangzhou 310006 China

Regenerating gene IV （RegIV）, a member of the regenerating gene family discovered in 2001, has been found to be involved in malignancy in several different organs including the stomach, colorectum, pancreas and prostate, but the overall expression profile of RegIV has not been reported. To learn more about RegIV, we evaluated its distribution by immunohistochemistry （IHC） in a total of 360 samples including 24 types of normal tissue, 40 benign and malignant lesions, and 18 neuroendocrine tumors. We found that in normal tissues, in addition to its relative specificity for the gastrointestinal tract, RegIV was detected in the adrenal gland and mammary gland. Among all the malignancies of various histological types under evaluation, RegIV was found mostly in adenocarcinomas. Studies on additional sets of colorectal tumor samples showed that RegIV expression was predominant in colorectal adenoma （87.5%） and peritumoral tissue （100%） but not in cancer tissue （30.8%）. Among neuroendocrine tumors, ReglV had a relatively restricted expression to those of digestive system.

关键词： Colorectal cancer Expression profile Neuroendocrine tumor Regenerating gene IV (RegIV)

DIFFERENTIATION BETWEEN MAliGNANT AND BENIGN OVARIAN TUMORS BY MAGNETIC RESONANCE IMAGING

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Sciences Journal 2006年第4期21卷 270-275页

作者： Min Chen Wen-chao Wang Cheng Zhou Ni-na Zhou Kui Cai Zheng-han Yang Wei-feng Zhao Sa-ying li Guo-zhen li Department of Radiology Beijing Hospital Beijing 100730

Objective To determine the magnetic resonance （MR） imaging findings of an ovarian mass which are most predictive of malignancy and assess the value of intravenous gadolinium administration in the characterization of an ovarian mass. Methods Totally 74 consecutive patients with a clinically or sonographicaUy indeterminate adnexal mass underwent MR imaging, of whom 59 had subsequent surgical resection of 70 adnexal masses. These 59 patients formed the study population. MR imaging studies were prospectively and independently reviewed by a senior and a junior radiologist. The senior radiologist also reevaluated the studies in a blind fashion after a minimum 6 months interval. The sensitivity, specificity, positive predictive value, and negative predictive value of contrast-enhanced and unenhanced MR im- aging were evaluated Results The most predictive MR imaging findings for malignancy were presence of vegetations in a cystic lesinn and presence of necrosis in a solid lesion. The odds ratio was even higher when the ancillary finding of peritoneal metastasis or ascites was present. Contrast media contributed significantly to lesinn characterization. Total 70 ovarian masses were detected by contrast-enhanced MR imaging including 37 malignant ovarian masses and 33 benign ovarian masses with 87% （61/70）accuracy, 86% （32/37）sensitivity, 88% （29/33）specificity, 89% （32/36）positive predictive value, and 85% （29/34） negative predictive value, whereas 70 ovarian masses were detected by unenhanced MR imaging with 74% （52/70） accuracy, 73 % （27/37） sensitivity, 76 % （ 25/33 ） specificity, 77% （27/35） positive predictive value, and 71% （ 25/35 ） negative predictive value. There were significant differences in accuracy （ P 〈 0. 01 ）, sensitivity （ P 〈0. 01 ）, specificity （ P 〈0. 01 ） between contrast-enhanced and unenhanced MR imaging. Conclusion Contrast-enhanced MR imaging is highly accurate in detection and characterization of complex adnexal masses.

关键词： ovarian tumor malignancy magnetic resonance imaging

Soluble CD4 effectively prevents excessive TLR activation of resident macrophages in the onset of sepsis

在线全文

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2023年第7期8卷 3498-3511页

作者： Sheng-yuan Zhang Qiu-ping Xu li-na Shi Shih-wen li Wei-hong Wang Qing-qing Wang liao-xun Lu Hui Xiao Jun-hong Wang feng-ying li Yin-ming liang Si-tang Gong Hao-ran Peng Zheng Zhang Hong Tang CAS Key Laboratory of Molecular Virology and Immunology Institut Pasteur of ShanghaiChinese Academy of SciencesShanghai 210031China The Third People’s Hospital of Shenzhen Shenzhen 518112China University of Chinese Academy of Sciences Beijing 100101China The Laboratory of Genetic Regulators in The Immune System Xin-xiang Medical UniversityXin-xiangHenan Province 453003China The Joint Center of Translational Medicine Guangzhou Women and Children’s Medical Center and Institut Pasteur of ShanghaiGuangzhou 510623China Department of Microbiology Naval Medical UniversityShanghai 200433China State Key Laboratory for Diagnosis and Treatment of Infectious Diseases National Clinical Research Centre for Infectious DiseasesCollaborative Innovation Centre for Diagnosis and Treatment of Infectious DiseasesThe First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China

T lymphopenia,occurring in the early phase of sepsis in response to systemic inflammation,is commonly associated with morbidity and mortality of septic *** have previously shown that a sufficient number of T cells is required to constrain Toll-like receptors(TLRs)mediated ***,the underlying mechanisms remains ***,we unveil that CD4^(+)T cells engage with MHC II of macrophages to downregulate TLR pro-inflammatory signaling.

关键词： CD4 TLR infections

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

英语二项式习语语序的认知机制

外国语文 2010年第3期26卷 68-73页

作者：冯丽颖重庆师范大学外国语学院重庆400047

影响二项式习语语序的因素有多种,着重研究其中的四种语义约束,即"形式标记"、"感知"、"强势"和"顺序像似"约束。研究结果表明这些约束是主客观互动的产物,也是人类的身体和大脑对物理世界、文化世界体验的产物。

关键词：二项式习语语序语义约束体验哲学