摘要：Hydrogen,regarded as a promising energy carrier to alleviate the current energy crisis,can be generated from hydrogen evolution reaction(HER),whereas its efficiency is impeded by the activity of ***,effective strategies,such as strain and interfacial engineering,are imposed to tune the catalysis performance of novel two-dimensional(2D)phosphorus carbide(PC)layers using first-principle *** findings show that P site in pristine monolayer PC(ML-PC)exhibits higher HER performance than C ***,constructing bilayer PC sheet(BL-PC)can change the coordinate configuration of P atom to form 3-coordination-P atom(3-co-P)and 4-coordination-P atom(4-co-P),and the original activity of 3-co-P site is higher than the 4-co-P *** an external compressive strain is applied,the activity of the 4-co-P site is enhanced whereas the external strain can barely affect that of 3-co-P ***,the graphene substrate enhances the overall activity of the BL-PC because the graphene substrate optimizes the?GH*value of 4-co-P site,although it can barely affect the HER activity of 3-co-P site and *** desirable properties render 2 D PC-based material promising candidates for HER catalysts and shed light on the wide utilization in electrocatalysis.

摘要：根皮素是一种从苹果树根皮、果实及叶中分离得到的天然二氢查耳酮类化合物,在多种植物中也有发现。根皮素具有抗炎、抑菌、抗肿瘤、降血糖等药理活性,有广泛的应用前景。根皮素的衍生化有助于提高其生物活性及改善水溶性。对根皮素衍生化的研究进展进行综述,为根皮素衍生物的研究利用提供参考。

摘要：以1台镗孔专机为例,叙述了PLC与变频器在机床电气控制中的基本应用与设计过程,并结合相关电气原理图具体地阐述PLC顺序程序设计和镗头、工作台采用变频调速的实现.

摘要：应用正交回归设计的多元标准加入法 ,在偶氮胂 - OP- HAc- Na Ac显色体系中 ,研究了具有代表性、且相互干扰严重的镧、钆、镝三种稀土组分的混合溶液中同时测定镧、钆、镝的方法。实验证明 ,三种稀土浓度在1× 10 - 7mol· L- 1～ 1× 10 - 5m ol· L- 1范围内 ,同时测定的相对标准偏差低于 4 .2 %。

摘要：针对现有的特征提取方法忽略文本局部和全局联系的问题,提出了基于多尺度特征提取的层次多标签文本分类方法。首先,设计了多尺度特征提取模块,对不同尺度特征进行捕捉,更好地表示文本语义。其次,将层次特征嵌入文本表示中,得到具有标签特征的文本语义表示。最后,在标签层次结构的指导下对输入文本构建正负样本,进行对比学习,提高分类效果。在WOS、RCV1-V2、NYT和AAPD数据集上进行对比实验,结果表明,所提模型在评价指标上表现出色,超过了其他主流模型。此外,针对层次分类提出层次Micro-F 1和层次Macro-F 1指标,并对模型效果进行了评价。

摘要：创意经济和创意产业已成为当下城市发展理论界关注和研究的热点,在此背景下,文章针对中国广告行业创意边缘化的现实,提出从根本上促进和提升广告行业创意水平的核心解决方案:实现广告创意的价值转换。具体方法可以参照建筑业,以广告主广告总投资额的比例收取创意费,或按广告播放后1年的产品销售额的比例收取创意费;进而思考广告创意发展的新趋势:娱乐化,互动化,媒体整合化,以真正实现中国广告的创新与发展。

摘要：为了研究汽车第二代轮毂轴承单元的整体受力情况，以某公司生产的二代轮毂轴承单元为例，采用SolidWorks设计软件建立了轮毂轴承单元的3D模型，导ANSYSWorkbench中进行整体受力情况的动力学仿真分析，得出其应力应变分析规律，将轮毂轴承零件部的仿真结果与产品的设计和使用要求进行对比，结果满足产品要求。有限元分析方法可节省轴承厂实际试验的时间和成本，同时为轮毂轴承的试验分析提供了理论支撑和参考依据。

摘要：为了优化发射药脱硝工艺,基于Box-Behnken设计的响应面法(RSM)对单孔发射药的脱硝工艺进行了优化。考察了水合肼浓度、反应温度和反应时间3个主要影响因素对单孔发射药脱硝过程中脱硝率的影响,并建立了以脱硝率为响应值的二次回归模型。结果表明:各因素对脱硝率的影响程度为水合肼浓度>反应时间>反应温度,且各因素之间交互作用不显著。所建立的二次回归模型相关系数为0.9774,在影响因素水平范围内进行多组实验,脱硝率的实验值与模型预测值之间吻合度较高,平均相对偏差为1.61%,表明所提出的二次回归模型可靠性较高,可用于对发射药脱硝过程中脱硝率的预测和工艺条件的优化。通过对脱硝前后单孔发射药的结构和燃烧性能的表征,进一步证实了梯度硝基单孔发射药表层及孔边缘硝酸酯基浓度呈梯度增加,具有优异的燃烧渐增性。

摘要：目的制备含有7种血清型肉毒毒素切割位点(SNAP25-VAMP)的特异性绿色荧光融合蛋白,在***中诱导表达,纯化后用于肉毒毒素活性测定。方法根据SNARE蛋白复合物中SNAPE25和VAMP基因序列及各血清型肉毒毒素(Bo NTs)的切割位点,设计合成含有SNAREs中突触小体(SNAP25)和突触小泡膜蛋白(VAMP)的Bam HⅠ-HIS6-SNAP62-Eco RⅠ-VAMP57C-TAA-HindⅢ(以下简称为SV)基因,连接至p ET-28a-GFP载体上,构建重组质粒p ET-28a-GFP-SV,转化感受态*** BL21(DE3),IPTG诱导表达后,经DEAE阴离子交换层析、Cu2+金属螯合层析、Q阴离子交换层析3步纯化,BCA法测定纯化产物的蛋白浓度,ELISA法检测B型肉毒毒素轻链蛋白(Bo NT/BL)活性。结果构建的质粒p ET-28a-GFP-SV经双酶切及测序鉴定证明构建正确,表达的GFP-SV融合蛋白相对分子量约40 000,主要以可溶形式存在,蛋白浓度为18.4μg/μl,纯度可达70%以上。利用该融合蛋白的荧光强弱变化可测定Bo NT/BL活性大小,同时也可测定其抗体中和活性大小。结论制备的含有SV的特异性绿色荧光融合蛋白在***中获得了高效表达,为后续各型肉毒毒素活性检测及抗体中和毒素活性检测奠定了基础。

摘要：Owing to the inherent central information processing and resource management ability,the cloud radio access network(C-RAN)is a promising network structure for an intelligent and simplified sixth-generation(6G)wireless ***,to further enhance the capacity and coverage,more radio remote heads(RRHs)as well as high-fidelity and low-latency fronthaul links are required,which may lead to high implementation *** address this issue,we propose to exploit the intelligent reflecting surface(IRS)as an alternative way to enhance the C-RAN,which is a low-cost and energy-efficient ***,we consider the uplink transmission where multi-antenna users communicate with the baseband unit(BBU)pool through multi-antenna RRHs and multiple IRSs are deployed between the users and *** can conduct either point-to-point(P2P)compression or Wyner-Ziv coding to compress the received signals,which are then forwarded to the BBU pool through fronthaul *** investigate the joint design and optimization of user transmit beamformers,IRS passive beamformers,and fronthaul compression noise covariance matrices to maximize the uplink sum rate subject to fronthaul capacity constraints under P2P compression and Wyner-Ziv *** exploiting the Arimoto-Blahut algorithm and semi-definite relaxation(SDR),we propose a successive convex approximation approach to solve non-convex problems,and two iterative algorithms corresponding to P2P compression and Wyner-Ziv coding are *** results verify the performance gain brought about by deploying IRS in C-RAN and the superiority of the proposed joint design.