Genomic organization of EDSV strain AA-2

The genomic organization of egg drop syndrome virus strain AA-2 isolated in China is reported here. The genome was found to be 32 838 bp in length, approximately 2 kb shorter than those of the human subgenus C adenoviruses. Analysis of open reading frames indicated that the genes for major viral structural proteins (55 K, Penton base, pⅦ, pⅩ, pⅥ, Hexon, 100 K, pⅧ and Fiber), as well as EP, DNA polymerase and ⅣaⅡ are present in the expected locations in the genome. EDSV possesses no identifiable E3 and E4 regions and most proteins encoded by E3 and E4 regions of other adenoviruses genome were not presented in EDSV.     

并联机器人及其机构学理论

介绍了并联式机器人,以及并联机器人机构学理论及其发展,特别介绍在称为２１世纪的新型机床;分析了并联机器人的结构,特点和广泛的应用前景。     

仔猪混合感染致病性白色葡萄球菌和大肠杆菌的诊断及防制初报

经过病原的分离鉴定、致病性试验及病仔猪防治效果的分析,确诊某集约化养猪场仔猪发生以“渗出性皮炎”为主的疾病为致病性白色葡萄球菌和大肠杆菌混合感染,通过采取综合的防制措施后,彻底控制本病的发生和流行。     

视黄酸对BEL—7402细胞酶活性及基因表达的影响

人肝癌ＢＥＬ－７４０２细胞分别以５μｍｏｌ／Ｌ、２０μｍｏｌ／Ｌ和５０μｍｏｌ／Ｌ的视黄酸（ＲＡ）处理后,细胞生长明显受抑,平均细胞群体倍增时间延长,并呈ＲＡ浓度及处理时间依赖性关系．经２０μｍｏｌ／ＬＲＡ处理的细胞中,ｒ－谷氨酰转肽酶（ｒ－ＧＴ）活性自给药后第２天即持续下降,至第６天降至４４．５％,而酪氨酸－α－酮戊二酸转氨酶（ＴＡＴ）活性则持续增高,至第６天较对照组高近１倍．经２０μｍｏｌ／ＬＲＡ处理５ｄ后,ＲＮＡ斑点杂交分析表明ｐ５３基因转录加强,而Ｎ－ｒａｓ基因表达下降,提示该两基因的表达变化可能在ＢＥＬ－７４０２细胞的生长抑制及逆转过程中起重要作用,有关机制尚待深入研究．     

第二类边界条件先进格林函数节块法

目前广泛应用的节块格林函数法是基于第三类边界条件,这类格林函数比较复杂,并且不便直接使用不连续因子,必须经过转换后才能使用和功率重构。该文发展了第二类边界条件三维几何先进格林函数节块法。该方法的优点是格林函数计算较简单,便于在交界面处引入通量不连续因子,并通过功率重构得出堆芯内精细通量分布。基准计算表明,该程序精度高、速度快,成为水堆堆芯物理设计和燃料管理计算的核心程序。     

干湿循环法制备抗菌性 5A 沸石

本文探索了制备抗菌性沸石的新方法———干湿循环处理法,采用５Ａ沸石分别与抗菌性离子Ｚｎ２＋、Ａｇ＋、Ｃｕ２＋的溶液进行干湿循环处理,制备抗菌性５Ａ沸石。研究了反应条件,如温度、浓度、循环次数对沸石中抗菌性离子含量的影响,找出了最佳反应条件。测试了抗菌性５Ａ沸石的耐洗涤性能和抗菌性５Ａ沸石对黑曲霉菌、大肠杆菌及嗜热脂肪芽胞杆菌的抗菌效果。研究结果表明,干湿循环法制备抗菌性沸石,具有抗菌性离子含量多,抗菌性能好,方法简便,反应时间短,节约原料等优点。     

An Electrostatic Bond Energy Model for Enthalpies of Formation of Chloroalkanes in Gaseous States

An electrostatic bond energy model is formulated to fit the enthalpies of formation and dipole moments of the alkanes and chloroalkanes. In this model, the charge distributions are calculated by an electrostatic approach similar to the "MSE" method, and the enthalpy of formation of a molecule is the sum of the bond energy terms plus the electrostatic energy of the interactions between the charges on all atoms. All parameters of this model are obtained by parameterization. The calculated dipole moments for 13 chloroalkanes and enthalpies of formation for 19 alkanes and non-geminal chloroalkanes agree with the determined values very well. To calculate the enthalpies of formation of geminal chloroalkanes, a correction mainly attributed to the van der Waals interactions in the geminal substituted group, about 24 kJ/mol per pair of geminal chlorine atoms, is introduced.     

Design and Synthesis of 1-Benzyl-3-(a-hydroxy-(un)substituted benzylidene)pyrrolidine-2,4-diones as Potential Herbicides

The inhibitors of 4-hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) are an new kind of herbicides.[1]Generally, in structure, potent herbicides of this kind must possess: (1) a tricarbonyl methane structure and one of the three carbonyl groups must be a subustituted benzoyl group; (2) the compound must be able to enolise so that the enolate is capable of inhibiting HPPD enzyme by competitive combination with Fe2+, the reaction center of HPPD enzyme.[2]Recently, we noticed that the 3-acyltetramic acids form an expanding group of antibiotics and pigments from micro-organisms,[3] they display a range of biological activities[4] and all of this kind compounds possess all of the characters mentioned above. Tests of their antimicrobial activities indicated that the structure of the acyl substituent at the 3-position was important to many typical antibiotics.[4～6] These characters stimulated us to study this kind of compounds so as to discover new herbicides. In this report, we synthesized a series of compounds 3 and tested their herbicidal activities to investigate their structure-activity relationships.     

Oligodeoxyribonucleotide analogues with bridging dimethylene sulfide,sulfoxide, and sulfone groups. Toward a second-generation model of nucleic acid structure

Short DNA analogues with bridging dimethylene sulfide, sulfoxide, and sulfone groups replacing the phosphate diesters (S-DNAs) were synthesized from building blocks prepared via two routes, both starting from D-glucose. Building blocks for RNA analogues were prepared by stereoselective introduction of nucleobase into a 2'-acylated ribose analogue. The ribose analogues were converted to deoxyribose analogues by replacement of a 3'-OH group by a thioacetyl unit, followed by photolytic deoxygenation or radical-based 2'-deoxygenation. DNA analogues joined via CH(2)(-)S-CH(2) units were prepared by S(N)2 displacement of a 6'-mesyl group on one building block using a thiolate nucleophile of another. 4,4'-Dimethoxytrityl protection and deprotection schemes were established for both the thiol and hydroxyl groups. The corresponding sulfoxide DNA analogues were obtained by oxidation with hydrogen peroxide. Sulfone DNA analogues were obtained by oxidation of the sulfide DNA with persulfate or hydrogen peroxide in the presence of a titanium silicate catalyst. The physical properties of several representative oligonucleotide analogues were examined, and interpreted in light of a "second-generation" model for DNA strand-strand recognition, a model that emphasizes the role of the polyanionic backbone in diminishing unwanted tendencies of highly functionalized molecules to form "structure" in solution. Even short sulfide-linked DNA analogues displayed association properties different from those displayed by standard DNA molecules. Complex formation observed with sulfide-linked tetramers by HPLC study in different solvents suggested that the complex is formed using hydrogen bonding. Sulfone-linked dinucleotides display Watson-Crick behavior; the tetramer, however, displayed self-structure. Self-structure and self-aggregation become more prominent as the length of the oligonucleotide analogues increases. The tendency to self-aggregate can be decreased by adding a charged sulfonate group to the 3'-end of the DNA analogue. Features of the second-generation model are important for many areas of nucleic acid chemistry, from the design of nucleic acid therapeutic agents to the search for life on other planets.     

A Facile Three-Component One-Pot Synthesis of Structurally Constrained Tetrahydrofurans, Which Are t-RNA Synthetase Inhibitor Analogues

A one-pot procedure for the efficient synthesis of a small library of t-RNA inhibitor analogues was developed. Thus,Rh2(OAc)4 catalyzed three-component 1,3-dipolar cycloaddition reactions of carbonyl ylides derived from diazoindan-1,3-dione and aldehydes with other dipolarophiles in 1,1,2,2-tetrachloroethane at 80 ℃ gave ring fused tetrahydrofurans having three stereocenters in good yield.