堆积的胸腺嘧啶体系光物理失活的动力学模拟

采用半经典动力学方法模拟了π堆积的胸腺嘧啶体系最低激发态的光物理失活过程.设置激光脉冲仅作用于一个胸腺嘧啶分子T,另一胸腺嘧啶分子T’保持基态.模拟发现由于T与T’之间存在π堆积相互作用,导致电荷转移,形成T带负电荷、T’带正电符的激基复合物.由于相邻分子的空间效应阻碍了激发的T分子到达圆锥相交所必需的强烈扭曲,激基复合物的寿命比单体增长.当分子间距离缩短至0.3 nm后,T分子C₅—C₆键扭曲程度最大,此时发生电荷重组,两个胸腺嘧啶分子均恢复电中性.电荷重组诱导T’分子发生畸变,并在C₅’—C₆’扭曲最大时避免相交,体系衰减至基态,T和T’分子均恢复平面构型.     

Comparative Spermatology of Protura and Its Significance on Proturan Systematics

A comparative study on the ultrastructure of the spermatozoa of 20 species of Protura belonging to 16 genera and 8 families was conducted. The most remarkable characteristics are the unexpected diversity of the spermatozoa, both in shape and fine structure. In general they can be grouped into two main categories: long flagellate spermatozoa and short aflagellate ones. Accordingly two sperm evolutionary lines of the spermatozoa were obtained: one trends towards the complicated acrosome structure and the increased number of axonemal doublets, and the other line is to shorten cell form and simplify sperm structure. The results indicate that the spermatozoa of Hesperentomon may be the primitive type, and the spermatozoa of Eosentomids probably represent the most evolved type. A sperm evolutionary tree was drawn according to the apomorphies of proturan spermatozoa. The phylogenetic position of Protura was also discussed.     

Comparison of the metabolism of baicalin in rats orally administered with Radix scutellariae extract and Shuang-Huang-Lian extract

Shuang-Huang-Lian (SHL) is a traditional Chinese formula containing Flos lonicerae, Radix scutellariae (RS) and Fructus forsythiae, and is commonly used for treating acute upper respiratory tract infection, acute bronchitis and light pneumonia. The aim of the present study is to compare the metabolites of baicalin in rats when orally administered with SHL and Radix scutellariae, and try to explore the principle of SHL compatibility. By using LC-MS(n) and HPLC-DAD, the metabolites of baicalin were analyzed from bile, urine and feces of rats dosed with SHL and RS. Our results showed significant difference of baicalin metabolism between RS and SHL. However, baicalein was found to be the main metabolites of baicalin in intestinal tract after oral administration of RS and SHL, glucuronide, glucoside and methylated products were also found in rat urine after administration of either RS or SHL. Meanwhile, several sulphates were found in rat urine after RS administration, but not found after SHL. Among the metabolites of the SHL, potentially there existed a isomerized baicalin and methylated product: 5,7-dihydroxy-6-methoxyisoflavone-7-O-beta-glucopyranuronoside, but without unidentified metabolite M3. Baicalein-6-O-beta-glucopyranuronoside-7-O-beta-glucopyranuronoside and baicalein-6-O-beta-glucose-7-O-beta-glucopyranuronoside were first reported by this study. The major metabolites of baicalin of RS and SHL in rat bile were the same, including baicalin-6-O-beta-glucopyranuronoside-7-O-beta-glucopyranuronoside, baicalin-6-beta-glucopyranuronoside and 6-O-methyl-baicalin-7-O-beta-glucopyranuronoside. Moreover, baicalein-6-O-beta-glucose-7-O-beta-glucopyranuronoside was also first found in rat bile by this study. Although baicalin-6-O-sulfate-7-O-beta-glucopyranuronoside was found in rat bile after RS administration, no sulphated products were found after oral administration of SHL. These differences of baicalin metabolism between RS and SHL indicated that compatibility of medicines could result in the differences of metabolites.     

三层流体系统非线性界面内波传播理论的研究

基于波陡很小的假设, 利用摄动法, 讨论了任意深度的二维不可压缩、无黏性、无旋的三层流体系统. 在刚性上边界、平底不可渗透条件下, 给出了界面内波传播的统一理论以及描述其波剖面的近似非线性演化方程(NEEs). 最后讨论了几种特殊情形下的近似NEEs.结果表明文献导出的理论结果为本文的特殊情形.     

溶剂浮选分离富集雪莲中的黄酮

采用溶剂浮选法分离富集雪莲提取液中黄酮类化合物.考察了浮选溶剂、氮气流速、试液pH、浮选时间及电解质NaC1等因素对浮选效率的影响,优选出最佳浮选条件;对最佳条件下的浮选结果进行了评价,并与溶剂萃取法进行了对照.结果表明:前者明显优于后者.     

Micro-FTIR study on structure of macerals from Jurassic coals in Northwestern China

Jurassic coal in Northwest China is rich in resources and it is a necessary premise to reveal the chemical structure characteristics of the coal macerals in this region before the coal is put into reasonable and efficient use. Micro-FTIR technique was used to investigate the chemical composition and structures of vitrinite semifusinite and fusinite from Jurassic coal in Northwestern China. The results show that vitrinite and semifusinite have more aliphatic hydrogen, but fusinite has more aromatic hydrogen and C=O structure. The aliphatic hydrogen in semifusinite is higher than that in fusinite and it is this structure characteristic of semifusinite that led to the richer inertinite but higher reactivity of the Northwestern China coal. Not only vitrinite but also semifusinite and fusinite with weaker reducibility have less aliphatic hydrogen and more C=O structures than those with stronger reducibility. The different intensity of oxidation in the process of coalification is one of the causes that led to different type of reducibility.     

Efficient Regioselective Synthesis of the Crotonyl Polydatin Prodrug by <Emphasis Type="Italic">Thermomyces lanuginosus</Emphasis> Lipase: a Kinetics Study in Eco-friendly 2-Methyltetrahydrofuran

Bio-based solvents have recently been discussed as sustainable green and promising alternatives to conventional organic media for enzymatic processes. In this paper, highly regioselective synthesis of the 6″-O-crotonyl-polydatin catalyzed by Thermomyces lanuginosus lipase (TLL) in biomass-derived 2-methyltetrahydrofuran (2-MeTHF) was successfully performed for the first time. The results indicated that TLL lipase displayed significantly improved catalytic performance in 2-MeTHF than in other traditional solvents. Under the optimal conditions, the initial reaction rate, 6″-regioselectivity, and maximum substrate conversion were as high as 12.38 mM h^?1, 100 %, and 100 %, respectively. Moreover, further investigations on the operational stability, kinetic parameters like V _max, K _m, V _max/K _m, and E _a revealed that 2-MeTHF exhibited excellent biocompatibility and rendered the greener process of the enzymatic acylation.     

Proton-Calcium Scattering at Tp=200 Mev in the α-Particle Model

Elastic proton-⁴⁰Ca scattering at T_p = 200 MeV is calculated within the Glauber theory on the basis of the α-particle model. The results are compared with the experimental data and those calculated in the relativistic model.     

光谱电化学研究α-巯基苯并噻唑对铜的缓蚀机理

我们运用现场光谱电化学方法研究了α-巯基苯并噻唑对铜的缓蚀机理。研究表明α-巯基苯并噻唑是通过在金属铜表面形成一层致密的非水溶性配合物膜Cu^Ⅰ-MBT而起缓蚀作用的。     

Study of fluorescence characteristics of the charge-transfer reaction of quinolone agents with bromanil

A spectrofluorimetric method was discussed for the determination of three antibacterial quinolone derivatives, ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CIP) through charge-transfer complexation (CTC) with 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, TBBQ). The method was based on the reaction of these drugs as n-electron donors with the pi-acceptor TBBQ. TBBQ was found to react with these drugs to produce a kind of yellow complexes and the fluorescence intensities of the complexes were enhanced by 29-36 times more than those of the corresponding monomers. UV-vis, (1)H NMR and XPS techniques were used to study the complexes formed. The various experimental parameters affecting the fluorescence intensity were studied and optimized. Under optimal reaction conditions, the rectilinear calibration graphs were obtained in the concentration range of 0.021-2.42 microg mL(-1), 0.017-2.63 microg mL(-1) and 0.019-2.14 microg mL(-1) for OFL, NOR and CIP, respectively. The methods developed were applied successfully to the determination of the subject drugs in their pharmaceutical dosage forms with good precision and accuracy compared to official and reported methods as revealed by t- and F-tests.