原子核裂变的发现：历史与教训——纪念原子核裂变现象发现60周年

回顾了原子核裂变发现走过的一段弯路，讨论了这段历史提供的启发和教训．     

Yields of products from fast neutron-induced fission of 233U measured by means of an isotope separator on-line (ISOL) system

A comprehensive study has been carried out of the yield pattern of fission products formed in fast neutron-induced fission of ²³³U. The isotope separator on-line facility at Studsvik to the R2-0 nuclear reactor was used for rapid separation of the fission products. At a target temperature of 2250 ^°C fission products of the elements from zinc (Z = 30) to barium (Z = 56) are released, with the exception of yttrium, zirconium, niobium, molybdenum, technetium, ruthenium and rhodium. The individual isotopes are then available for study, implying that an almost complete mapping of the yield distribution can be made. In the analysis, the delay between production and measurement and the overall separator efficiency for three consecutive elements (the one under study and its parent and grand parent) are taken into account. Independent and/or cumulative yields have been obtained for 203 nuclear species, among them 59 isomeric states. Received: 19 April 2000 / Accepted: 19 June 2000     

Preparation and biological evaluation of key fragments and open analogs of scleritodermin A

The synthesis of key fragments of scleritodermin A, their assembly, and their biological evaluation as cytotoxic and anthelmintic were performed. Highlights of the synthetic route include formation of the α-ketoamide linkage and use of stereocontrolled reactions. Open analogs of this natural product were obtained using a convergent strategy.     

AFLP在水稻线粒体DNA研究中的应用

对 Ａ Ｆ Ｌ Ｐ应用于水稻线粒体基因组研究中的问题进行了研究结果表明： Ａ Ｆ Ｌ Ｐ分析对ｍ ｔ Ｄ Ｎ Ａ 质量要求高,ｍ ｔ Ｄ Ｎ Ａ 应完整并反复抽提以达高纯度 ｍ ｔ Ｄ Ｎ Ａ 不完全酶切所造成的假阳性可经第二次酶切排除选择引物一个选择碱基最适合水稻ｍ ｔ Ｄ Ｎ Ａ Ａ Ｆ Ｌ Ｐ分析 另外,研究表明从银染后未经烘烤的新鲜银染凝胶回收的 Ｄ Ｎ Ａ 扩增效果好、产物经纯化可直接用于克隆以及探针标记     

Synthesis and spectroscopic properties of cross-conjugated ketones and meso-substituted tridecamethine salts containing the pyran or pyridone fragment

The reactions of substituted 4H-pyrones and N-methyl-2,6-dimethylpyridone with dimethylformamide acetal and aminal acetals of conjugated -dimethylaminoaldehydes were studied. Cross-conjugated ketones and meso-ethoxy(dialkylamino)tridecamethine salts containing the pyran or pyridone fragment were synthesized and their spectroscopic properties were investigated. The replacement of the bridging O atom by the NMe group precludes an interaction between chromophores in cross-conjugated ketone and the related tridecamethine salt. In addition, the insertion of a meso-amino substituent into the polymethine chain of the salts containing the central pyrylium fragment leads to a sharp weakening of the chromophore interaction. In spite of the dramatic differences in the UV spectra of ketocyanines containing the bridging O or NMe fragments, these dyes have similar ¹³C NMR spectra.     

Synthesis and characterization of cationic latex particles bearing sulfhydryl groups and their use in the immobilization of Fab antibody fragments (1)

Emulsion copolymerization of styrene and a cationic monomer vinylbenzyl-isothiouronium chloride (VBIC) with initiation by 2,2 azobis(2-amidinopropane)-dihydrochloride (V-50) gave monodisperse latex particles. After post-stabilization with cationic or non-ionic surfactants, the colloids were diluted in basic buffers with concomitant deprotection of the sulfhydryl groups. Therefore, coupling reactions on the latex beads were possible. Coupling conditions were determined with Ellman's reagent.¹⁴C iodoacetamide and anti C-reactive protein antibody Fab fragments were immobilized and finally, the immunological activity of the sensitized latex was assessed.     

Phase evolution,structural characteristics and mechanism of vesicle formation from a synthetic amphiphile: Controlled morphology by tuning solution phase parameters

We report herein, the aggregation behavior of 3, 4-di(dodecyloxy)benzoic acid-4-hydroxy phenyl ester (DDBE), a synthetic amphiphile and a true non-ionic surfactant system as per the geometrical considerations. The true surfactant nature of the system stems from its hydrophilic-lipophilic-balance (HLB?=?4.7), comparable to that of Span-60, also a true non-ionic surfactant. This compound undergoes spontaneous vesicle formation in THF:water binary solvent mixtures which further underwent fission at lower DDBE concentrations and fusion at higher concentrations, leading to giant vesicles of the order of 3000?nm. These vesicles are sensitive to the polarity of their environment. The predominant mode of interaction as observed from the molecular dynamics simulations were found to be π-π stacking with the phenyl rings of the molecule. Further, the system, upon complete extraction into water, formed spherical aggregates of size 50?nm based on the good solvent-poor solvent combination as the necessary condition for the vesicle formation.GRAPHICAL ABSTRACT     

Diversity of interstrand π—π stacking motifs in the double helices of pyridinedicarboxamide oligomers

Winding of oligoamide strands of 2,6-diaminopyridine and 2,6-pyridinedicarboxylic acid into molecular duplexes is illustrated by two new crystal structures of double helical dimers. The relative positions of the two strands within the double helices in these two structures are different; they also differ from the structures reported previously. Unlike the single helical structure of the monomeric strands, the double helical motif is not highly stable in the solid state. This implies that the interactions that lead to duplex formation are not directional. It suggests that the two strands have a significant motional freedom in the duplex.     

Inverse-flow derivatization for capillary electrophoresis of DNA fragments with laser-induced fluorescence detection

A novel method is presented to detect DNA fragments separated by capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection using inverse-flow derivatization. In electrophoresis, the intercalating dye, thiazol orange was only added to the separation buffer at the positive polarity. The negatively charged DNA fragments migrated from the negative polarity to the positive polarity, while the positively charged dye migrated in the opposite direction. When DNA fragments met with dye ions, the DNA–dye complexes were formed. The complexes continued migrating to the positive end, due to their net negative charges. When the complexes passed through the detection window, the fluorescent signals were generated. Importantly, DNA fragments migrated as their native state before DNA–dye complexes were formed. This procedure was used to detect double stranded DNA (dsDNA) and single stranded DNA (ssDNA) fragments, and polymerase chain reaction (PCR) products. The excellent resolution and good reproducibility of DNA fragments were achieved in non-gel sieving medium. This procedure may be useful in genetic mutation/polymorphism detections.     

高效液相色谱法分离纯化人胎盘泌乳素酶切片段

高效液相色谱法分离纯化人胎盘泌乳素酶切片段杨煜,杨波,麦荫乔（白求恩医科大学长春１３００２１）１前言人胎盘泌乳素（Ｈｕｍａｎｐｌａｃｅｎｔａｌｌａｃｔｏｇｅｎ,ＨＰＬ）是由胎盘绒毛滋养层的合体细胞分泌的一种单链多肽类激素。它主要有催乳作用￣［１］及促...