过硫酸钾氧化-荧光分光光度法测定片剂中叶酸的含量

在 p H=3,80℃水浴加热 1 0 min,以 36 5 nm为激发波长 ,在 4 41 nm波长处测定 K2 S2 O8氧化叶酸的产物蝶呤 - 6 -羧酸的荧光强度 ,间接测定叶酸的含量。线性范围为 5× 1 0 -5mol/ L— 1× 1 0 -6mol/ L,检出限为3.0× 1 0 -7mol/ L。本法测定叶酸片剂中叶酸的含量 ,回收率为 1 0 1 .8%— 1 0 9.0 %。     

日本医蛭和天目山蛭4种同工酶的比较研究

采用垂直平板聚丙烯酰胺凝胶电泳对日本医蛭和天目山蛭的酯酶（ES）、苹果酸脱氢酶（MDH）、过氧化物酶（POX）、乳酸脱氢酶（LDH）4种同工酶共计11个位点的15个乘闰基因进行了分析，4种同工酶基因在2种蛭中表达程度以及LDH同工酶酶谱相似，但是日本医蛭比天目山蛭ES同工酶多2个位点，3个基因；MDH少1个基因；POX同工酶多2个位点，2个基因；LDH同工酶等位基因表达的亚单位类型和数目不同。同时分析了冬眠与非冬眠期日本医蛭LDH同工酶活性差异的原因，为在分子水平研究蛭类分类、不同环境温度下酶的活性变化等提供和积累新的生物学资料。     

卵母细胞的卵龄对猪核移植效率的影响

对核移植中,猪卵母细胞的卵龄对核移植效率的影响进行了研究结果表明：体外成熟培养 ４８ ｈ 的猪卵母细胞最适合作为核受体,其激活率达 ７８．３％ ,并无裂解;去核率高达９０％ ;在作为核受体进行核移植时,融合率为７５％ ;重构胚胎的卵裂率为６４．６％ 卵龄进一步增大,激活率略有增加,但去核率、融合率和卵裂率均下降     

Nine New Sesquiterpenes from Dendrobium nobile

Nine new sesquiterpenes, i.e., dendronobilins A–I ( 1 – 9 ), with copacamphane‐type ( 1 ), picrotoxane‐type ( 2 – 6 ), muurolene‐type ( 7 ), alloaromadendrane‐type ( 8 ), and cyclocopacamphane‐type ( 9 ) skeletons, were isolated from the 60% EtOH extract of the stems of Dendrobium nobile. Their structures were established as (1R,2R,4S,5S,6S,8S,9R)‐2,8‐dihydroxycopacamphan‐15‐one ( 1 ), (2β,3β,4β,5β)‐2,4,11‐trihydroxypicrotoxano‐3(15)‐lactone ( 2 ), (2β,3β,5β,9α,11β)‐2,11‐epoxy‐9,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 3 ), (2β,3β,5β,12R*)‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 4 ), (2β,3β,5β,12S*)‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 5 ), (2β,3β,5β,9α)‐9,10‐cyclo‐2,11,13‐trihydroxypicrotoxano‐3(15)‐lactone ( 6 ), (9β,10α)‐muurol‐4‐ene‐9,10,11‐triol ( 7 ), (10α)‐alloaromadendrane‐10,12,14‐triol ( 8 ), and (5β)‐cyclocopacamphane‐5,12,15‐triol ( 9 ) on the basis of spectroscopic analysis. The absolute configuration of compound 1 was tentatively assigned as (1R,2R,4S,5S,6S,8S,9R) according to its CD spectrum and the octant rule. Compounds 1 and 4 – 9 were inactive in our preliminary in vitro immunomodulatory bioassay.     

Structural and spectral studies of ammonium mucicate

Ammonium mucicate C₆H₈O₈(NH₄)₂,M _r=244.20, monoclinic,P2₁/a,a=13.460(2),b=7.289(2),c=5.109(2)Å,=94.96(4)°,Z=2, molecular symmetry ¯1,V=499.4(3)ų,D _x=1.62 Mg m^–3,(MoK)=1.03 cm^–1,F(000)=260, room temperature. Final conventionalR value is 0.030 (Rw=0.037) for 1272 diffractometer-measured intensities withI3(I). The crystal structure is characterized by an extended system of hydrogen bonding involving the ammonium cations and the mucicate anions. The four hydroxyl groups are all involved as donors and acceptors in intermolecular bonds. The IR-spectra in the crystalline state have been recorded and compared to that of mucic acid.     

Double cyclization of aminophosphonoacetate derived β- hydroxyacids to bicyclic β-lactams

The carbon framework for carbapenems was constructed by an asymmetric aldol condensation and subsequent direct coupling of the resulting β-hydroxy acid equivalent with an aminophosphonoacetate. Cyclization to the monocyclic β-lactam 20 was followed by oxidative elaboration to the penultimate aldehyde 22 which was converted to carbapenem 23 by an intramolecular version of a Horner-Emmons cyclization.     

纳米半导体材料SO~_4(2-)/La-α-Fe_2O_3的表面结构与酒敏特性

对纳米半导体材料 SO2 -4/La-α-Fe2 O3 进行了 IR、XPS分析和比表面积测定实验 ,并制成厚膜型酒敏元件 ,探索了焙烧温度与灵敏度的关系以及气敏元件的稳定性。结果表明 ,样品中 SO2 -4与 La-α-Fe2 O3 表面的金属离子 (Fe3 + 或 La3 + )结合构型是无机桥式配位型 ,SO2 -4的加入使 Fe2 p3 /2 电子结合能从 71 0 .85 e V提高到 71 2 .1 0 e V,表面 Fe3 + 在 SO2 -4的作用下显示出更正的电位 ,从而改变了半导体性质 ,由 p型转变成为 n型 ;在焙烧温度为 45 0℃烧结的 SO2 -4/La-α-Fe2 O3 元件 ,对酒精的灵敏度最高 (S=3 5 .7)、稳定性好。     

In-situ Synthesis of Binderless ZSM-5 Zeolitic Coatings on Aluminum

ZSM-5 zeolitic coatings on aluminum have been prepared successfully by in-situ hydrothermal synthesis method and ZSM-5/Al monolith was formed. The effects of pH value and crystallization time on the in-situ synthesis were discussed.     

Corrosion Behavior of Carbon Steel in Lithium Bromide Solution

Weight‐loss tests and electrochemical techniques are used to study the inhibition of BTA and Na₂MoO₄ either individually or in different combinations for carbon steel in boiling 10.24 mol/L LiBr solution containing 0.07 mol/L LiOH. The result indicates the corrosion of carbon steel is effectively inhibited when BTA or Na₂MoO₄ is added to the solution individually. The adsorptions of BTA or Na₂MoO₄ on carbon steel surfaces can be well fitted to a Langmuir adsorption isotherm. The free energy of adsorption of BTA and Na₂MoO₄ are ?45.07 kJ/mol and ?40.69 kJ/mol, respectively. The corrosion rate is decreased to the minimal value, which is 8.39 μm/y, when 7.28 × 10^?4 mol/L Na₂MoO₄ and 8.39 × 10^?4 mol/L BTA are added to a 10.24 mol/L LiBr solution containing 0.07 mol/L LiOH. The inhibition mechanism of the above mixed inhibitors results from the complemental effect of the compact inner layer film composed of Fe‐BTA and the absorbed MoO₄^2? in small quantity of the active site and the outer layer. The passive film of the coordination compound and the adsorbed MoO₄^2? prevent Br^? from absorbing and effectively decrease the corrosion of carbon steel.     

The setereoselective preparation of baker's yeast in the presence of rice wine koji

By the addition of rice wine koji, enhancement of the reactivity was observed for the baker's yeast reduction of P-keto esters into (S)-β-hydroxy esters with high enantiomeric purity(73-98%).