Subjects: Library Science，Information Science >> Information Science submitted time 2023-04-01 Cooperative journals: 《图书情报工作》
Abstract： [Purpose/significance] The behavior of academic literature downloading is an essential step in the process of academic retrieval. Predicting download behavior of academic literature is conducive to the in-depth understanding of the retrieval behavior of researchers, and provides a basis for optimizing retrieval results of academic resource retrieval platforms and restructuring ranking, to improve the retrieval function and service quality of retrieval system.[Method/process] This paper constructed a multi-dimensional feature system of researchers' academic literature download behavior, and proposed two sub-classifiers based on query relevance and user behavior respectively relying on machine learning algorithms. A weighted strategy was adopted to construct a hybrid model of download behavior prediction of academic literature.[Result/conclusion] The experiment results show that the Random Forest algorithm achieves the best performance in both classifiers. Compared to the model trained with only query relevance features, the accuracy of the hybrid model is increased by 2.3%, and the F1 value is increased by 1.3%. The sub-classifiers based on user behavior have higher weights in the hybrid model. "downloads" "whether professional/advanced search is used"and "published time" make a significant contribution to the academic literature download prediction task.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： This study analyzes the situation of China’s foreign trade from January to November in 2020, and then three forecasting scenarios are constructed based on four aspects, including China’s economic growth, the international demand, Sino-US trade friction, and the development of the COVID-19. Under these scenarios, a new decomposition and composition methodology is proposed to forecast 2021 China’s foreign trade, by integrating the econometric models, artificial intelligence methods, and the system analysis method. In 2021, under the baseline scenario that the COVID-19 pandemic will be under certain control, the global economy exhibits slow recovery and China’s economy grows steadily, the total exports and imports in 2021 are expected to be around 4.9 trillion US dollars with a 5.7 percent growth rate year-on-year. Exports are expected to be around 2.7 trillion US dollars with a 6.2 percent growth rate year-on-year, and imports are expected to be around 2.2 trillion US dollars with a 4.9 percent year-on-year growth rate. The trade surplus is about 576.6 billion US dollars. Under optimistic scenario in 2021, China’s export and import growth rates are expected to increase by 3.0 and 3.3 percentage points relative to the baseline scenario, respectively. Under pessimistic scenario in 2021, China’s export and import growth rates are expected to decrease by 2.9 and 3.2 percentage points relative to the baseline scenario, respectively.
Subjects: Biology >> Botany submitted time 2022-12-29 Cooperative journals: 《广西植物》
Abstract：
AP2/ERF transcription factors play important roles in plant growth, development and stress response. In order to explore the roles of AvAP2/ERF genes in salt tolerance, we identified AP2/ERF gene family in Aquilegia vulgaris transcriptome via bioinformatic methods, and then investigated their physical and chemical properties, conserved motifs, phylogenetic relations, and expression patterns of these genes in leaves and roots under salt stress. The expression of candidate genes was verified by qRT-PCR. The results were as follows：(1) 86 AvAP2/ERF genes were identified which encoded 154-722 amino acids, the molecular weight was 14 763.3-79 069.47 Da and isoelectric point ranged from 4.49 to 9.68. Most of them were slightly acidic proteins and all of them were hydrophilic. Most of AvAP2/ERF were localized in nucleus. (2)The similarity of secondary structure was high, which was proportionally composed of random coil and α-helix. The members all contained AP2 domains, and two conserved motifs were predicted. (3) In different stages of salt treatment, 71 AvAP2/ERF genes responded to salt stress. There were18 and 19 differentially expressed genes in leaves and roots, respectively. 86 AP2/ERF genes of Aquilegia vulgaris were divided into 5 subfamilies clustering with Arabidopsis thaliana; AvAP2/ERF-56、AvAP2/ERF-61 and AvAP2/ERF-80 of them might be involved in salt resistance, and the qRT-PCR results were consistent with sequencing expression trends. This study provides a reliable reference for further research on the function and stress response mechanism of AP2/ERF gene in Aquilegia vulgaris.
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics submitted time 2017-11-07 Cooperative journals: 《工程热物理学报》
Abstract：本文通过使用各向同性湍流燃烧的可压缩DNS数据库对二阶矩(SOM)燃烧模型进行了先验性检验和评价。通过检验，发现忽略密度脉动和三阶脉动关联量是可行的，可以有效地简化反应速率方程。通过对关联量输运方程中的精确项的检验，发现化学反应项的贡献最大，需进行准确的封闭。通过对模化的输运方程的检验，发现部分精确项的模化效果不理想，但总体来说，SOM燃烧模型的思想和方法是可行的，有待进一步的发展。
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-07 Cooperative journals: 《中国腐蚀与防护学报》
Abstract：采用冲击破坏、盐雾、紫外、湿热等加速循环腐蚀试验方法，对比分析在不同加速循环周期下的电化学阻抗谱(EIS)的变化特点。结果表明，涂层阻抗在腐蚀中后期增加，并出现新的时间常数，可对应于金属表面氧化膜的溶解，及铝基体腐蚀有关。随着腐蚀循环的进行涂层的吸水量先增加后减少，吸水率最终稳定在5%左右。
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