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1.
检测了66例子宫肌瘤患者血清中超氧化物歧化酶(SOD)和丙二醛(MDA)的含量,探讨其与子宫肌瘤发病的关系。结果表明,子宫肌瘤患者血清中SOD的活性较健康妇女明显降低,而MDA含量明显增加,两者呈负相关,提示自由基在子宫肌瘤的发病中起着重要作用.  相似文献   

2.
长期低浓度铅暴露对人体微量元素的影响   总被引:3,自引:1,他引:2  
测定了15名长时间从事低剂量铅接触的女工血铅、铜、锌、铁、锰及铜锌超氧化物歧化酶活性、脂质过氧化产物二级降解物丙二醛含量,并以同年龄组同地区非铅暴露人群作对照。结果显示:暴露组的血铅、铜、MDA含量高于对照组;而血锌Cu-Zn-SOD活性低于对照组;血Mn、Fe两组无明显差异。  相似文献   

3.
成年小鼠每天腹腔注射0.28mmol/kg剂量的toCl3、La-DTPA、TbCl3和Tb-DTPA生理盐水溶液,连续三天后与生理盐水对照组比较,LaCl3使小鼠肝脏脂质过氧化(LPO)水平升高,超氧歧化酶(SOD)活性降低,而TbCl3的影响不明显;LaCl3和TbCl3均显著降低谷恍甘肽过氧化酶(GSH-Px)活性。同样剂量La-DTPA和Tb-DTPA对上述三项指标基本无影响。  相似文献   

4.
徐通敏  周天舒 《分析化学》1995,23(2):123-127
本文研究了Nafion化学修饰钨丝圆盘预富集-石墨炉原子吸收方法测定牛血超氧化物歧化酶中淳离态Cu^2+及Zn^2+的方法,并用GFAAS法直接测定SOD中铜、锌的总量,证实了牛血SOD中金属辅基铜、锌原子个数比为1:1;初步探讨了一定浓度的牛血SOD中Cu^2+,Zn^2+的表观离解平衡常数,为提高SOD的活性和稳定性的研究,提供了一种有效的方法。  相似文献   

5.
改变硅源和晶化时间合成了系列SAPO5分子筛.用原位红外光谱和NH3TPD研究了不同样品的酸碱性,用TGDTA和MASNMR考察了硅源及晶化时间对分子筛模板剂的影响,评价了不同样品对正己烷裂解的催化活性.结果表明,SAPO5分子筛孔道不仅与模板剂的胺基有作用,而且与其甲基也有作用.以硅凝胶为硅源时,在48h内,延长晶化时间可使分子筛中硅含量和强酸中心数目增加,低温下正己烷裂解活性提高;晶化72h时,分子筛的酸性减弱,正己烷裂解活性降低.以正硅酸乙酯为硅源时,延长晶化时间可使SAPO5的酸性增强,正己烷裂解性能提高.  相似文献   

6.
肖天存  安立敦 《催化学报》1998,19(2):144-148
改变硅源和晶化时间合成了系列SAPO-5分子筛,用原位红外光谱和NH3-TPD研究了不同样品的酸碱性,用TG-DTA和MAS NMR考察了硅源及晶化时间对分子筛模板剂的影响,评价了不同样品对正己烷裂解的催化活性。结果表明,SAPO-5分子筛孔道不仅与模板剂的胺基有作用,而且与其甲基也有作用。以硅凝胶为硅源时,在48h内,延长晶化时间可使分子筛中硅含量和强酸中心数目增加,低温下正己烷裂解活性提高;晶  相似文献   

7.
CuZSM-5分子筛上苯酚羟化制苯二酚   总被引:4,自引:0,他引:4  
在Na2O-SiO2-CuO-H2O体系中以15%TPABr-85%HMDA为模板剂合成了CuZSM-5分子筛,并用XRD,IR及SEM等方法进行了表征,考察了CuZSM-5分子筛催化苯酚与过氧化氢的羟化活性,研究了催化剂用量、反应温度、反应时间及n(PhOH)/n(H2O2)等对羟化活性的影响.  相似文献   

8.
CuZSM—5分子筛上苯酚羟化制苯二酚   总被引:1,自引:0,他引:1  
于剑锋  张春雷 《催化学报》1997,18(2):130-134
在Na2O-SiO2-CuO-H2O体系中以15%TPABr-85%HMDA为模板剂合成了CuZSM-5分子筛,并用XRD,IR及SEM等方法进行了表征,考察了CuZSM-5分子筛催化苯酚与过氧化氢的羟化活性,研究了催化剂用量,反应温度,反应时间及n(PbOH)/n(H2O2)等对羟化活性的影响。  相似文献   

9.
用气相流动吸附法(grafting)制备复合载体,用浸渍法(impregnation)制备MoO3/(TiO2-SiO2)催化剂.应用LRS和TPR技术研究MoO3在复合载体TiO2-SiO2表面的分散状态,发现TiO2在SiO2表面的分散可增强MoO3与载体之间的相互作用,提高MoO3在载体表面的分散阈值.催化剂的活性评价在固定床中压反应装置中进行,以69%(wt)环己烷、20%(wt)的环己烯、10%(wt)的苯、1%(wt)的噻吩混合液为反应液,以噻吩、环己烯和苯的转化率作为催化剂的HDS、HYD、BHD活性指标.结果表明,经TiO2调变后,其HDS、HYD、BHD活性都较原来高,对于不同MoO3含量的MoO3/(TiO2-SiO2),HDS、HYD催化性能测试发现,当MoO3含量低于分散阈值时,其HDS、HYD活性随MoO3含量线性上升,但在高于分散阈值后,几乎保持不变.该催化剂对苯几乎没有加氢活性,显示出很高的环己烯加氢选择性.通过分散阈值与其HDS、HYD活性的关系可知,分散阈值可作为优化加氢精制催化剂配比的一个重要参数,具有较强的实际意义  相似文献   

10.
MALDI-TOF-MS法分析人血清白蛋白   总被引:1,自引:0,他引:1  
用基质辅助激光解吸附飞行时间质谱(MALDI-TOF-MS)法分析测定了人血清白蛋白。结果表明,全军血液制品研究中心应用Rivanol和Cohn's两种方法分离提取的人血清白蛋白,其分子量与理论计算值相吻合,其纯度与市售标准人血清白蛋白相一致,用MALDI-TOF-MS法分析鉴定人血清白蛋白,准确、简便和灵敏(仅需PM浓度样品),且重复性好,日内和日间差的变异系数均小于0.03%,是SDS-PAGE电泳法所无法比拟的。  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

13.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

14.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

15.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

16.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

17.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

18.
A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.  相似文献   

19.
Zhanhui Yang  Shiyi Yang  Jiaxi Xu 《Tetrahedron》2017,73(23):3240-3248
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.  相似文献   

20.
A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.  相似文献   

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