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1.
研究了在三氯甲烷致突变性试验中加入硒的影响。结果显示硒能减少Ames试验中三氯甲烷诱变的回变菌落数,能使小鼠骨髓嗜多染红细胞微核率和鳙鱼外周血有核红细胞微核率明显下降。并研究了硒在细胞免疫试验中的作用,结果显示硒能使正常鼠和荷瘤鼠的肺和脾的NK细胞活性提高,能促进其脾T淋巴细胞的增殖反应,还能增加外周血T淋巴细胞数。  相似文献   

2.
The intramolecular Diels-Alder reaction (IMDA) stands as the t'undamental strategy inour total synthesis of hainanolide l, to assemble the tricyclic skeleton. ring B. C and D.as it was reported 1. Cyclization of triene 2 afforded a mixture of endt,-IMDA-additive3 and exo-IMDA-additive 4, the ratio of which varied with reaction conditions. Yetneither 3, with the C2. hydrogen at a position, nor 4, with the C, methyl at a position.fits the configuration of that in the natural product. The…  相似文献   

3.
库仑滴定法测定有机硅样品中的氮含量   总被引:3,自引:0,他引:3  
谢择民  王清正 《分析化学》1993,21(2):206-208
本文利用库仑滴定法研究了高分子和低分子硅氮化合物及含氮有机硅样品中氮含量的测定,并研究和讨论了影响测定结果准确性的因素。  相似文献   

4.
Inpreviousworksonmodificationsofnorditerpenoidalkaloids,wereportedsomeimportantreactionssuchasN-deethylationandpreparationsoftheimmesand7,17-secoderivatives'.NowwewishtorepoFtoxidationofthenorditerpenoidalkaloidsisotalatizidineand6-epiforsticine.Oxidationofnorditerpenoidalkalnidshavinganla-hydroxylgroupwithreagentssuchasKMnO.K,Fe(CN),,OsO.,Ag,OandNBSaffordedcompoundswithanO,Nmixedacetalsystems=.Thus,treatmentofisqtalatizidineIwithKMnO.inacetone-H,O(5;1)forIhgavetheknowncompoundnevade…  相似文献   

5.
中药微量元素含量区间尺最佳分级问题的探讨   总被引:1,自引:0,他引:1  
在深入研究中药微量元素含量区间尺的基础上,从统计学角度对区间尺的最佳分级问题作了详细探讨,提出用5级区间尺来衡量中药中不同元素含量间相对高低水平,理论上更合理。  相似文献   

6.
测定了健康正常分娩的产妇49例的母血,脐带血和正常未孕妇女50例的血清铜,锌含量,结果表明,分娩期母血清中铜,锌,铜/锌比值低于未际妇女,有显著差别,铜未见差别,母血清中铜与铜/锌比值均高于脐血清中值,有显著差别,母血清中锌明显低于及早血清中值并有显著差别,分娩期血清中铜,锌值与胎儿体重关系无显著差异;胎膜早破与非胎膜早破无妊娠合并症者血清中铜,锌未发现差别,提示妊娠母亲血清中微量元素锌,铜与胎儿的生长发育有关。  相似文献   

7.
用原子吸收光谱法测定了70例健康老年人、30例健康成年人和30例老年高血压病人血清中Cu、Zn、Fe、Mn、Ca、Mg6种元素的含量.结果表明,健康老年人组与健康成年人组(对照组)相比,除Fe以外,Cu、Zn、Mn、Ca、Mg均有显著性差异;与老年高血压病人组相比,除Mg以外,Cu、Zn、Fe、Mn、Ca均有显著性差异.我们认为稳定的Cu/Zn比值及较高的血Mg水平是健康老年人未发生心血管疾病及糖尿病的重要原因之一,而高Cu、高Ca及显著偏高的Cu/Zn比值,则是发生高血压的一个重要原因。  相似文献   

8.
On the basis of the temporal evolutions of the singly, doubly and triply ionized tin (Sn II, Sn III and Sn IV, respectively) spectral line intensities, in the pulsed helium and nitrogen plasmas, the important role of the He I and He II metastables has been observed in the Sn II, Sn III and Sn IV ionization and population processes. According to these processes, one can expect realization of several laser levels in the Sn II (11.07, 11.20, 12.44 and 13.11 eV), Sn III (15.91, 17.82, 19.13 and 20.19 eV) and Sn IV (20.51 eV) spectra. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in helium with tin atoms, as impurities, evaporated from tin cylindrical plates located in the homogenous part of the discharge tube. This plasma source provides good conditions for a generation of the Sn III, Sn IV and Sn V ions at relatively low electron temperatures (below 18,000 K) providing low background radiation around the intense Sn IV and Sn III spectral lines in the helium plasma. The 222.613 ± 0.0005 nm Sn IV line, not observed up to now, has been identified. The marked, but not classified 243.688 nm Sn spectral line is sorted by ionization stages. The shapes of Sn III and Sn IV lines, ranged between 207 nm and 307 nm, have been obtained. At a 17,500 K electron temperature and 1.07 × 1023 m− 3 electron density the Stark broadening was found as the dominant mechanism in the mentioned lines broadening. The measured Stark widths of the prominent nine Sn IV and seven Sn III lines are the first data in the literature. The Stark widths of the intense 229.913 nm and 288.766 nm Sn IV lines can be used for the plasma electron density and temperature diagnostics purposes.  相似文献   

9.
大鼠饲料分别加入2×10-6、4×10-6硒.饮用7.5×10-6、15×10-6氟水.1个月后,随尿硒粪硒排量增加,尿氟排量也增高,以2×10-6硒饲料排氟效果最佳.血浆中ALP、GOT、GPT及LDH等酶活性加硒组有不同程度的降低.随后两次增高氟水量重复试验,给以2×10-6硒饲料,仍观察到尿氟排量增高.血中含硒酶谷胱甘肽过氧化物酶活性也有升高趋势,脑及肾中脂质过氧化物(LPO)含量明显减少,病区患者服硒后,尿氟含量亦高于对照组.实验结果提示;1)硒能促使体内氟由尿中排出;2)降低某些组织LPO含量;3)减少体内氟含量;4)预防和改善氟中毒某些临床症状。  相似文献   

10.
采用原子吸收分光光度法对广东沿海五个养殖场的牡蛎外套膜和内脏团中微量元素含量进行测定,并对其测定结果作初步探讨.发现测定牡蛎外套膜中微量元素的含量也能反映环境污染的情况及生物体内的富集情况.  相似文献   

11.
急性脑血管病患者血清元素的测定   总被引:3,自引:1,他引:3  
采用高频等离子体发射光谱法测定了34例脑梗塞、33例脑出血和对照组27人血清锌、铜、锰、铬、镁、钼、锶、铁、钛、钡、镉和钙共12种元素的含量。结果显示脑梗塞和脑出血组血清锌和锌/铜比值显著高于对照组;锰和钼含量仅在脑梗塞组明显增高,锶仅在脑出血组显著增高,而其它几种元素疾病组与对照组无显著性差异。伴有高血糖、高血脂和高血压的病人,其血铬含量显著降低,表明锌、锌/铜比值、锰、钼、锶、铬元素与急性脑血  相似文献   

12.
Summary The aim of the Education and Training Group of the Analytical Division of the Chemical Society is to improve education and training in Analytical Chemistry at all levels: in universities, in industry, and in all establishments where Analytical Chemistry is practised. Teaching methods, the interface between education and employment and other current problems are dealt with in the form of lectures and discussions. The Group also undertakes a continuing series of questionnaires to monitor the development in this field. A biennial prize is sponsored with the intention of stimulating the interest in Analytical Chemistry amongst young people in the U.K.Presented at Euroanalysis III conference, Dublin, August 20–25, 1978  相似文献   

13.
丁基罗丹明B-碲钼杂多酸缔合显色反应的研究   总被引:1,自引:1,他引:1  
李祖碧  徐其亨 《分析化学》1993,21(3):272-275
本文研究了在聚乙烯醇(PVA)存在下,丁基罗丹明B(BRB)与碲钼杂多酸的离子缔合显色反应,碲钼杂多酸在0.025~0.075 mol/L硫酸溶液中形成丁基罗丹明B-碲钼杂多酸离子缔合物。形成酸度为1.26~2.16 mol/L硫酸,钼酸铵、丁基罗丹明B及PVA的适宜条件分别4.6×10~(-3)mol/,5.3×10~(-5) mol/L和0.16%。缔合物最大吸收波长为570 nm,表观摩尔吸光系数ε值为3.2×10~5 L·mol~(-1)·cm~(-1),符合比耳定律范围0~16μg Te/25ml。探讨了反应机理,用平衡移动法确定缔合物的摩尔比为Te:Mo:BRB=1:7:2,缔合物的可能化学式为(BRB)_2[TeMo_7O_(24)]。方法已用于烟尘中碲的测定,结果满意。  相似文献   

14.
多波长线性回归法用于同时光度测定铁和铜   总被引:6,自引:2,他引:6  
赵书林  张乔 《分析化学》1993,21(1):86-89
在弱酸性介质中,在乳化剂OP存在下,铁、铜与PAN形成最大吸收均在550nm处的水溶性有色络合物,两者相互严重干扰。本文采用多波长回归分析法对此混合显色体系进行研究,选择在570~590nm区间,测定11个波长处的吸光度,使用简易程序计算器,进行数据回归处理,可简便快速地直接求出铁、铜的含量。应用于铝合金中铁、铜的同时测定,结果满意。  相似文献   

15.
Summary. Highly substituted 1-methylenecyclohexenepoxides 3, useful building blocks for a projected synthesis of wailupemycin A (1), were synthesized from (R)-carvone in eight synthetic steps in 23–40% overall yield. The regioselectivity of the subsequent isomerisation to the corresponding allylic alcohols was shown to depend on the basicity of the reagent and on the bulkiness of the protecting groups existing in 3. With diethylaluminum 2,2,6,6-tetramethylpiperidid (DATMP), secondary allylic alcohols 5 were formed exclusively. With strong bases such as a mixture of lithium di-iso-propylamide and potassium tert-butoxide (LIDAKOR), the tertiary allylic alcohol 6 was obtained as predominant product.To whom inquiries about the X-ray analysis should be addressed  相似文献   

16.
对微量元素与恶性肿瘤关系的新认识   总被引:3,自引:0,他引:3  
微量元素与恶性肿瘤关系是当前十分引人注目的研究课题.MEDLINE数据库显示.近5年中硒、锌、铜与肿瘤关系的文章最多.微量元素与恶性肿瘤相关性有三种可能,即微量元素的丰缺是恶性肿瘤的结果.是肿瘤发生的条件因素或病因.微量元素之间的关系相当复杂.既拮抗。又协同,微量元素的研究刚起步.取样和检测方法等均需标准化.其与恶性肿瘤的发生和发展的机理更需积极研究.  相似文献   

17.
Remark JF  Reynolds CA 《Talanta》1976,23(9):687-689
A non-aqueous direct titration procedure has been developed for the determination of aldehydes and ketones. It uses two platinum-wire indicating electrodes with a constant current of 0.5 muA. The solvent medium is 0.15M sodium perchlorate in tetrahydrofuran. The titrant is sodium fluorenyl in a mixture of 1,2-dimethoxyethane and tetrahydrofuran. All types of carbonyl compounds react with the sodium fluorenyl, but steric hindrance prevents complete reaction with certain ketones containing bulky groups. The lowest concentration of carbonyl that can be determined with acceptable accuracy and precision is 7.5 x 10(-3)M, the error being < 3% and the precision better than +/-2.5%. Most reducible compounds interfere, e.g., peroxides, acid halides, nitro-compounds, acids, and water, and cannot be differentiated potentiometrically. The method can be extended to other reducible functional groups, e.g., nitro groups and acid chlorides.  相似文献   

18.
丁云杰  梁东白 《分子催化》1993,7(4):293-298
本文应用动态脉冲吸附技术测定了H_2和CO的吸附量,结合透射电镜(TEM)和程序升温还原(TPR)等表征技术考察了活化条件对金属Ru粒子化学环境的影响.发现活化条件对Ru催化剂H_2和CO吸附量的影响很显著,H_2和CO低温吸附量随焙烧温度的升高而锐减;改由在惰性气体中焙烧或载体经HCI或HF预处理,大大增加了低温吸附量.TEM测定结果表明:金属Ru平均粒径(?)值随焙烧温度(在623K以下的范围内)的升高而减小,说明在此活化条件下处理的催化剂,其低温H_2和CO化学吸附量不能反映金属的分散度.TPR结果说明在空气中焙烧催化剂,Ru非氧化物前身转变成为RuO_2,并且导致金属与载体之间产生较强的相互作用,改变金属Ru粒子的化学环境,吸附活化能垒增高,在低温下H_2和CO的吸附量很小.  相似文献   

19.
通过原子吸收光谱技术对68例治疗前甲亢病人(A组),35例治疗后甲亢病人(B组),5例甲减病人(C组)及74例正常人(D组)全血多种微量元素测定分析,结果显示:D组Cu与Al,Mg与Mn正相关;Al与Zn、Se负相关;A组Fe与Zn、Ca,Ca与TT4。Cu与Mn正相关,TT与Zn、Cr负相关。B组Fe与Zn、Cu、Mg,Zn与Cu、Mn、Mg与Ca、Se、Se与TT3正相关。  相似文献   

20.
The phase behavior of fluid mixtures is understood by the critical lines in fluid-gas diagrams. We investigated the critical lines of polymer-solvent systems at the mathematical double point, where two critical lines meet and exchange branches, and its environment within the framework of a model that combines the lattice gas model of Schouten, ten Seldam and Trappeniers with the Flory-Huggins theory. The critical lines are expressed as a function of x1 and x2, the density of type 1 polymer molecules and the density of type 2 polymer molecules, respectively; in this way global phase diagrams are presented and discussed in the density-density plane. Density-density plots are preferable when studying the differences in behavior of different classes, since they enable us to follow the connectivities in a systematic way. In this study the connectivity of critical lines at the mathematical double point and its around is investigated in detail. We also discuss the topology of the critical lines according to the Sadus classification scheme for ternary mixtures.  相似文献   

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