串联系统的可靠性

本文利用侯振挺等人提出的马尔可夫骨架过程理论讨论了串联系统的改进模型的可靠性.     

The Quality of Statistical Reporting and Data Presentation in Predatory Dental Journals Was Lower Than in Non-Predatory Journals

Proper peer review and quality of published articles are often regarded as signs of reliable scientific journals. The aim of this study was to compare whether the quality of statistical reporting and data presentation differs among articles published in ‘predatory dental journals’ and in other dental journals. We evaluated 50 articles published in ‘predatory open access (OA) journals’ and 100 clinical trials published in legitimate dental journals between 2019 and 2020. The quality of statistical reporting and data presentation of each paper was assessed on a scale from 0 (poor) to 10 (high). The mean (SD) quality score of the statistical reporting and data presentation was 2.5 (1.4) for the predatory OA journals, 4.8 (1.8) for the legitimate OA journals, and 5.6 (1.8) for the more visible dental journals. The mean values differed significantly (p < 0.001). The quality of statistical reporting of clinical studies published in predatory journals was found to be lower than in open access and highly cited journals. This difference in quality is a wake-up call to consume study results critically. Poor statistical reporting indicates wider general lower quality in publications where the authors and journals are less likely to be critiqued by peer review.     

铁基金属有机凝胶衍生的三氧化二铁纳米片用于光芬顿降解罗丹明B

光催化剂在工业废水处理中发挥着重要作用. 本工作以室温下一步合成的片状铁基金属有机凝胶(Fe-based Metal-organic gel, Fe-MOG)为前驱体, 在不同温度下煅烧得到了片状(300-Fe₂O₃和400-Fe₂O₃)和球形(500-Fe₂O₃和600-Fe₂O₃)两种形貌的衍生三氧化二铁(Fe₂O₃). 通过一系列测试手段对衍生Fe₂O₃的晶体结构和光电性能进行了表征. 其中, 具有碳骨架结构的400-Fe₂O₃因其优良的电子传输性能和较高的光生电荷分离效率表现出优异的光催化活性, 可在中性条件下60 min内光降解97.5%的罗丹明B (Rh B), 并且在连续五次循环实验后其降解效率仍能达到85.3%. 本工作为开发和设计具有优异催化活性的半导体光催化剂提供了新的思路.     

多环笼状骨架有机物的简易命名法*

将多环笼状骨架有机物在绘图软件ChemDraw中用“橡皮擦”分步擦去短桥转化为二环体系明确其主环和主桥头,其后在此化合物的结构式中用记号标明其主环和主桥头,按多环化合物的编号原则进行编号命名,即可得到此复杂结构有机物的命名。     

Solvable Systems of Equations Modeled on Some Spines of 3-Manifolds

We show solvability of the systems of equations modeled on certain spines of 3-manifolds. We extend a result by Duncan and Howie about the 2-skeleton of the 3-torus.     

Some presentations for the special linear groups on finite fields

We simplify the Steinberg presentation of SL _n (F _d ), where n≥1 and F _d is any finite field with d elements. That presentation has the elementary matrices e _ij (r), with i,j∈{1,...,n}, i≠=j and r∈F _d , as generators, and (E1)–(E3), described at the opening of this work, as relations. The presentation that we shall obtain reduces the number of generators e _ij (r) and relations (E1)–(E3). In particular, relations (E3) are considerably reduced. Received: March 16, 1998; in final form: November 3, 2000?Published online: October 2, 2001     

Mosaic approximations of discrete analogs of Calderón-Zygmund operators

Asymptotic estimates of the form mrA = O(InN · ln ^d ɛ ⁻¹), whered is the dimension of the initial space, for mosaic ranks of discrete analog of Calderón-Zygmund operators are obtained for various mosaic covers. Translated fromMatematicheskie Zametki, Vol. 63, No. 1, pp. 81–94, January, 1998.     

N-策略休假GI-X／G／1排队系统队长的瞬时分布

本文应用Markov骨架过程理论研究了N-休假策略GI~X/G/1排队系统,并得到了队长的瞬时分布.     

带干扰的理赔为一般到达的风险模型

本文应用M arkov骨架过程方法,研究了带干扰的理赔为一般到达的保险风险模型,得到了破产时间与破产时刻前后资产盈余的联合分布以及破产时间的分布.