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排序方式: 共有312条查询结果,搜索用时 15 毫秒
1.
提出了一种基于小波统计特征的朝汉文种识别方法.首先计算行文档图像的垂直及水平方向的投影;其次对垂直方向的投影及水平方向的投影进行一维小波分解并分别计算小波统计特征,然后将两个方向上的小波统计特征进行合并作为该文档图像的特征向量(本文方法构造的特征向量仅为11维);最后通过神经网络进行训练和测试,结果显示平均测试准确率超过94%. 相似文献
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用模糊聚类分析法划分建设工期定额地域类别 总被引:2,自引:0,他引:2
在分析了建设工期定额的自然建设条件的基础上,采用模糊聚类分析法划分地域类别,并以平均模糊加权数确定各类地域类别系数。此方法可应用于工程项目建设工期定额的修订与完善,以及建设工期定额的执行和建设工期的决策与管理。 相似文献
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Chen Xiuqing Ma Kai Geng Deqin Zhai Jingxuan Liu Wei Zhang Hongwei Zhu Tingting Piao Xue 《Wireless Personal Communications》2019,109(3):1747-1767
Wireless Personal Communications - In order to support robust implementation of IoT, many schemes have been done to provide privacy, anonymity, scalability and customizability. Ray et al.’s... 相似文献
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Hanwen Sun Zhansheng Kang Hui Li Jingxuan Zhang Yunkai Lv 《Food Analytical Methods》2012,5(4):643-650
A new method for multi-residue determination of five synthetic glucocorticoids (betamethasone, dexamethasone, prednisone, prednisolone, and hydrocortisone) in milk powder is developed. The glucocorticoids in the samples were extracted with tert-butyl methyl ether under ultrasonication incubation, and then cleaned up through gel permeation chromatography. After C18 LC gradient elution separation using acetonitrile with 0.1% formic acid as a mobile phase, the eluents were determined by liquid chromatography–tandem mass spectrometry with multiple reaction monitoring and positive ionization modes. The effective separation for the five glucocorticoids was achieved. The limit of quantification of the method for testing five glucocorticoids in milk powder was in the range from 0.2 to 0.5 μg kg−1, which was lower than the maximum residue limits established by European Union for glucocorticoids in foods. Experiments on spiked samples of milk powder showed that the mean recoveries at addition level of 1.0, 3.0, and 5.0 μg kg−1 were in the range of 71.2% and 103%, and the relative standard deviation ranged from 4.7% to 16.8%. The calibration curves for these drugs between 1.0 and 100 μg l−1 showed good linearity, with correlation coefficient (r) more than 0.999. The real sample test showed that this method is sensitive and accurate. It can be used for qualitative and quantitative determination of studied glucocorticoid residues in milk powder samples. 相似文献
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Yuchen Zhang Naijun Dong Huanle Hong Jingxuan Qi Shibo Zhang Jiao Wang 《International journal of molecular sciences》2022,23(5)
Due to aging of the world’s population, stroke has become increasingly prevalent, leading to a rise in socioeconomic burden. In the recent past, stroke research and treatment have become key scientific issues that need urgent solutions, with a sharp focus on stem cell transplantation, which is known to treat neurodegenerative diseases related to traumatic brain injuries, such as stroke. Indeed, stem cell therapy has brought hope to many stroke patients, both in animal and clinical trials. Mesenchymal stem cells (MSCs) are most commonly utilized in biological medical research, due to their pluripotency and universality. MSCs are often obtained from adipose tissue and bone marrow, and transplanted via intravenous injection. Therefore, this review will discuss the therapeutic mechanisms of MSCs and extracellular vehicles (EVs) secreted by MSCs for stroke, such as in attenuating inflammation through immunomodulation, releasing trophic factors to promote therapeutic effects, inducing angiogenesis, promoting neurogenesis, reducing the infarct volume, and replacing damaged cells. 相似文献
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三塔式循环流化床(TBCFB)是基于低阶煤分质转化利用理念开发的新型工艺系统,包含热解、气化及燃烧三个主反应器。提出了采用半焦颗粒代替石英砂作为循环热载体的新工艺,并使用Aspen Plus建立了基于半焦颗粒的TBCFB系统模拟流程,寻求系统内物料转化和能量利用的适宜操作条件。结果表明,只需燃烧40%的热解半焦,即可满足低阶煤在600℃热解和60%的热解半焦在800.9℃进行水蒸气气化所需热量;与石英砂或高温灰相比,利用热容较高的半焦颗粒作为循环介质可以显著降低热载体循环量,与原煤质量比仅为5.5。综合气化产物组成、低热值和冷煤气效率等指标,适宜的水蒸气与反应半焦质量比为1.5。上述模拟结果对半焦循环TBCFB新技术的工业应用具有一定指导意义。 相似文献