高等学校学科知识联盟

借用企业知识联盟的一些思想,阐述了高校学科知识联盟的形式、意义以及构建方法。     

双层钙钛矿Sr2FeMoO6，Ba2FeMoO6的电磁性质研究

分析了双层钙钛矿结构的锰氧化合物Sr2FeMoO6,Ba2FeMoO6物相结构和电磁学性质,对巨磁阻效应进行了探讨,揭示了Sr2FeMoO6样品为半导体导电性,Ba2FeMoO6样品为金属导电性.     

Sul meccanismo di azione della streptomicina

Summary A study was undertaken on the variations of the redox potential level produced by streptomycinin vitro andin vivo. We have been able to show that, owing to an oxidative effect, streptomycin produces an increase of the redox potential level. This oxidative effect varies in degree according to the condition of the patient.We also found that in the blood and in the spinal fluid of patients suffering from tubercular meningitis factors are present which inhibit the action of streptomycin.The results of our findings lead to the conclusion that the dose of streptomycin must be varied according to the condition of the patient if the constant level required for an efficient therapy is to be maintained in the blood and in the spinal fluid.     

Kondensationsprodukte von Oxyketonen und Aminoketonen mit 2,4,5-Triamino-6-oxy-pyrimidin

Summary By condensing 2:4:5-triamino-6-hydroxy-pyrimidine with dihydroxyacetone (diacetate), diaminoacetone or acetone-1,3-di (p-formylaminobenzoic acid) not the expected 8- or 9-oxymethyl resp. -aminomethyl-pteridines but 8-or 9-methyl-pteridines were obtained. With p-tolyl-d-isoglucosamine not a tetrahydroxybutyl-pteridine but a trihydroxybutyl-pteridine was formed. For an explanation of these results it is supposed that from the dihydro-pteridines formed at first by intramolecular splitting off of H₂O or R·NH₂ aromatization takes place.     

A propos d'antibiotiques insolubles

Summary The authors show the antibiotic activity of water-insoluble salts of hydrosoluble antibiotics in the case of penicillin G (salts of iron, copper, silver, gold, and uranium) and streptomycin (oleate).     

板料成形数值模拟中摩擦的处理及应用

针对板料成形过程中工件与模具不同的接触条件，采用常摩擦模型，提出相应的摩擦应力的处理方法．在此基础上，通过实际的模拟分析，证明了该处理方法的可行性．同时探讨了摩擦对成形结果的影响．模拟结果表明，板料与凹模和压边圈之间的摩擦阻碍了金属向凹模内流动，对板料拉深成形是不利的，而增大凸模与板料之间的摩擦则可以有效限制制件侧壁的变薄，这对成形是有利的．     

证券投资组合理论和无差异曲线

文章通过无差异曲线解释了最优证券投资组合并探讨了对现代投资组合理论三个主要组成部分的有关内容.     

中老年梗阻性大肠癌102例的临床分析

目的分析8年来中老年梗阻性大肠癌的临床特点和外科治疗。方法回顾性总结我院1993～2001年102例中老年梗阻性大肠癌的临床治疗资料。结果大肠癌梗阻占老年急性肠梗阻的50.45%,居首位。梗阻发生部位以右半结肠区最多,占54.58%,左半结肠区仅占13.49%;所有患者均经手术治疗,其中一期切除吻合80例,占78.4%;短路手术18例,占17.6%;单纯造瘘术4例,占3.9%;死亡2例,死亡率2%。结论提高对中老年梗阻性大肠癌临床特点的认识,正确地选择手术时机和合理的手术方式能获得良好的预后。加强围手术期各器官功能支持和营养代谢支持是减少死亡率的重要环节。重视老年生理变化特点,警惕肿瘤所致的消化道症状,早期诊治大肠癌以减少肠梗阻发病率。     

浅析基于电子商务网络安全PKI技术的角色访问控制模型

文本提出了一种区别于传统自主访问控制策略和强制访问控制策略的RBAC网络安全策略,并提出了RBAC的面向对象模型,实现用户身份认证与访问权限的逻辑分离,且易于控制,既能有效的改进系统安全性能,又极大地减少了权限管理的负担。