14-去甲基自溶霉素C11～C15片段的合成研究

研究了14-去甲基自溶霉素C11^C15片段的合成.自溶霉素及类似物具有较好的抗癌活性,其全合成引起了广泛关注.以L-谷氨酸为手性原料,经8步完成了14-去甲基自溶霉素C11C15片段的合成.自溶霉素及类似物具有较好的抗癌活性,其全合成引起了广泛关注.以L-谷氨酸为手性原料,经8步完成了14-去甲基自溶霉素C11^C15片段的合成.其中,应用了NaBH4/BF3·Et2O还原羧酸,以及质子海绵/Me3OBF4实现邻硅氧基醇甲基化的方法.     

放射性核素14C在生物学中的应用

从分子生物学、古生物学及生物医学3个方面论述了放射性核素14C的应用,并指出了其应用的缺陷及今后在应用研究中应注意的问题。     

超分子C14H14N4O8的合成及结构表征

以反丁烯二酸和咪唑为原料,采用缓慢蒸发溶剂法合成了新的有机加合物C14H14N4O8,并获得了其单晶体.通过红外、热化学分析、X-射线单晶衍射等技术对该加合物进行了结构测定和性质表征.晶体中分子通过分子间氢键相互连接构成超分子网络结构.该加合物属于三斜晶系,P-1空间群,a=0.746 77(15), b=7.736 3(15),c=8.405 5(17),α=69.73(3)°,β=80.40(3)°,γ=66.19(3)°,Z=1,V=416.75(14)A3,D=1.468 (mg/m3),F(000)=190.     

14C measurement of forest soils in Dinghushan Biosphere Reserve

Organic carbon in forest soils of Qingyunsi and Wukesong profiles can be divided into fast and slow components. Δ 14C values of these profiles decrease with increasing of depth. The Δ 14C values in 30-40 cm depth interval of Wukesong profile are decreasing sharply until a very low value, showing that a strong geological environment change occurred about 1 560 years ago. The 14C apparent ages of Wukesong profile show that the coniferous and broad-leaf mixed forests around Wukesong profile have been developing since 425 a BP, which is consistent with historical documents. The penetrating depths of "bomb 14C" in Qingyunsi and Wukesong profiles are 10 and 20 cm, respectively.     

表面δ力(SDI)+四极力(QI)与~(14)C核能谱

本文用组态混合方法,选择SDI+QI作为有效相互作用,计算了~(14)C的能谱,计算结果同实验值符合的很好。同时也用SDI作为有效相互作用计算了~(14)C的能谱,比较发现,SDI+QI比单纯的SDI作为有效相互作用有明显的改进。     

纳米TiO2光催化降解甲基橙的研究

用XRD表征了TiO2的晶体形态,并用紫外可见光广度计研究了其对紫外光的吸收.通过研究TiO2的添加量和甲基橙的初始浓度对甲基橙的降解速率的影响,得出最佳实验条件为TiO2的添加量2.5g/L,甲基橙的初始浓度12.25mg/L.用光还原法在TiO2上沉积Ag后,催化剂的光催化活性大大提高.     

Effect of dead carbon on the ^14C dating of the speleothem

Based on the comparison of dating results among high-precision TIMS U-series and AMS ^14C as well as the published ^14C dating results and their band counting ages(i.e. calendar ages), this paper discusses the effect of dead carbon on the speleothem ^14C dating. The result shows that the fraction of incorporated dead carbon during the formation of speleothem varies. The change in the fraction of dead carbon would result in big deviation in the ^14C age of the speleothem. It is indispensable to take the dead carbon into consideration when dating the speleothem using the ^14C method or studying the atmospheric ^14C concentration during the past with the speleothem.     

B_(13)C_2型C_(14)N晶体结构及弹性性质的第一性原理研究

采用基于密度泛函理论的第一性原理计算方法,研究了B13C2(B12CBC)中B12二十面体所有B原子被C原子取代,以及C-B-C三原子链中B原子被N原子取代后材料的性质变化.通过对比计算研究发现,取代后得到的化合物C14N体积减小、弹性性质进一步提高、金属性增强、材料的理论硬度有所改善.C与C明显形成方向性强的类金刚石四面体键,有利于其弹性的提高.     

14C dating of moss peat banks in Fildes Peninsula, Antarctica

Based on the radiocarbon data of the moss peat banks in Fildes Peninsula, Antarctica, it was calculated that the mean rates of peat accumulation in the upper layer and the lower layer are 0.195 and 0.069 4 mm · a^™1 respectively. Based on the radiocarbon date (3 265 ± 120 aBP) and the mean rate of peat accumulation in the lower peat layer, it was calculated that the age of the coast terrace on which the moss peat bank occurs is earlier than 4 300 aBP. During the past 4 300 years the coast terrace has risen about 18 m without apparently being destroyed, and the age of the glacier retreating process in this area is also earlier than 4 300 aBP.     

基因工程菌株EscherichiacoliC600（pRLK14）的流加培养

在１Ｌ搅拌发酵罐中对含有重组质粒ｐＲＬＫ１４的大肠杆菌进行了培养。结果表明，采用二段培养法，于３４℃增殖细菌，在对数增殖后期升温到４２℃进行诱导，可以高效表达基因产品半乳糖激酶。诱导期，醋酸浓度增长较快，模拟实验表明，控制醋酸浓度可进一步提高半乳糖缴酶产率。     

碘电极测定饮用水中的碘和碘离子

应用碘电极,采用亚砷酸钠为碘的还原剂进行前处理,选用磷酸二氢钠为总离子强度缓冲液,测定了总碘及碘离子含量.建立的方法对三碘树脂净水器净化后的水进行了测定,结果良好.当总碘和碘离子的浓度在10-7～10-4范围内时,相关系数为0.999 9,回收率大于98.1%.由实验测定的电位选择系数可见,该法选择性好,检测下限低.