摘要：Solar-driven water splitting is considered as a promising method to mitigate the energy crisis and various environmental *** vanadate(BiVO_(4))is photoanode material with tremendous potential for photoelectrochemical(PEC)water ***,its PEC performance is severely hindered owing to poor surface charge transfer,surface recombination at the photoanode/electrolyte junction,and sluggish oxygen evolution reaction(OER)*** this regard,a novel solution was developed in this study to address these issues by decorating the surface of BiVO_(4)with cobalt sulfide,whose attractive features such as low cost,high conductivity,and rapid charge-transfer ability assisted in improving the PEC activity of the BiVO_(4)*** fabricated photoanode exhibited a significantly enhanced photocurrent density of 3.2 m A cm^(-2)under illumination at 1.23 V vs.a reversible hydrogen electrode,which is more than 2.5 times greater than that of pristine BiVO_(4).Moreover,the Co S/BiVO_(4)photoanode also exhibited considerable improvements in the charge injection yield(75.8%vs.36.7%for the bare BiVO_(4)film)and charge separation efficiency(79.8%vs.66.8%for the pristine BiVO_(4)film).These dramatic enhancements were primarily ascribed to rapid charge-transport kinetics and efficient reduction of the anodic overpotential for oxygen evolution enabled by the surface modification of BiVO_(4)by Co *** study provides valuable suggestions for designing efficient photocatalysts via surface modification to improve the PEC performance.

摘要：This paper,from three aspects including construction conditions,foundation design and construction,introduces some considerations in the designing of main-pylon foundations and some practical measures to deal with certain unfavorable construction conditions,such as deep water,tidal effect,soft stratum and heavy traffic,during the construction of main-pylon foundations.

摘要：为提高剑杆织机的车速,通过研究其传动系统各构件的主轴等效转动惯量变化规律、分布规律,织机惯性载荷的变化规律等,获取了织机各运动构件对主轴等效转动惯量的占比规律。针对幅宽360 cm的WL680型剑杆织机,通过结构优选,剑头剑带的质量减轻28.26%,传剑轮的转动惯量减少45.73%,设计样机。经仿真验证:优化后的样机降低等效惯性载荷约27%,织机幅宽减小,其效果明显下降。经实物样机测试验证:相同车速条件下,优化后样机振动和功耗明显降低,最高运行速度提高约7%~8%。研究结果表明:虽然剑头剑带的质量、传剑轮的转动惯量较小,但对主轴等效转动惯量的影响敏感,减小其质量和转动惯量能有效减小织机惯性载荷、降低织机振动和功耗、提高织机车速。

摘要：根据骨架迁跃原理,设计并合成了一系列具有酪氨酸激酶抑制剂拉帕替尼(Lapatinib)和诺拉替尼(Neratinib)结构片段的水杨酰芳胺类化合物,其结构均经IR,1H NMR,13C NMR和MS确证.采用四甲基偶氮唑盐(MTT)法考察所合成化合物的体外抗肿瘤细胞(A549,MCF-7,SGC-7901,Bel-7402)活性.结果表明,所合成的化合物对4种肿瘤细胞增殖均有一定的抑制活性,部分化合物的活性强于阳性对照药吉非替尼(Gefitinib).

摘要：随着移动通信技术的快速发展,移动终端的漫游接入、用户隐私保护等问题日益突出,面向移动网络的匿名漫游认证方案相继被提出.其中,部分方案通过生成临时身份代替真实身份的方法实现用户身份匿名性,并通过更新认证身份的方法防止攻击者跟踪;部分方案将漫游认证信息交由家乡认证服务器验证的方式实现移动终端的身份确认.上述方案普通存在认证效率低或认证时延长的问题.鉴于此,基于代理签名的思想,提出了一种移动网络匿名漫游认证方案.利用家乡认证服务器的代理授权,移动终端生成代理签名信息,外地认证服务器通过认证代理签名信息可直接完成对移动终端身份的合法性验证.分析表明,该方案实现了移动终端的匿名性、不可否认性、无关联性、抗伪造攻击等安全功能,同时,与既有方案相比降低了移动终端的计算负载和通信时延.

摘要：依据生物电子等排原理,设计合成了13个全新结构的1,2-苯并噻嗪类化合物,其结构均经IR,1H NMR,13C NMR和MS确证.以A431,A549,MDA-MB-468和HL60 4种细胞株为活性筛选对象,采用四甲基偶氮唑盐(MTT)法进行初步的体外抗肿瘤活性研究.结果表明,部分化合物对肿瘤细胞有一定的抑制活性,其中化合物5b对A431具有显著的抑制活性,IC50值为1.57μmol/L,化合物9a对A431,A549和MDA-MB-468 3种细胞株的抑制活性均强于阳性对照药gefitinib.并采用Moe软件对所合成的化合物与表皮生长因子受体(EGFR)结合位点进行对接,以进一步阐释所合成化合物的作用靶标.

摘要：背景:长跑训练中流行的观点是通过提高步频可以提高跑步效率,这需要多方面的科学评价及研究。目的:通过比较个体无氧阈强度下自选步频与改变步频后机体的心率、摄氧量、表面肌电和步态特征的变化,探究改变步频对跑者产生的影响,为提高跑步效率提供科学策略。方法:选择12名男性马拉松跑步爱好者。在试验开始前,首先通过跑台递增负荷试验进行有氧能力测试,得到跑者的通气无氧阈及无氧阈速度。在正式试验开始后,采用随机交叉设计,在无氧阈跑速下,进行自选步频、自选步频±5%和自选步频±10%跑台测试。使用配对t检验和皮尔逊相关分析等方法对心率、摄氧量、表面肌电和步态特征等指标进行统计分析,探究改变步频后各指标的变化规律。研究方案的实施符合北京体育大学的相关伦理要求,受试者对试验过程完全知情同意。结果与结论:①心率和摄氧量:改变步频后,心率显著增加(P<0.01),步幅发生显著变化(P<0.01),自选步频-5%(P<0.05)和自选步频±10%(P<0.01)时摄氧量显著增加;步幅和与摄氧量呈正相关关系(r=0.57,P<0.01),步频/步幅与摄氧量呈负相关关系(r=-0.42,P<0.01);②表面肌电:自选步频+10%时,股二头肌、股直肌和股内侧肌平均功率频率(MPF)显著增加(P<0.05);自选步频-5%(P<0.05)和自选步频-10%(P<0.01)时胫骨前肌平均功率频率显著增加;自选步频+5%时,股直肌肌肉贡献率显著下降(P<0.05);③步态特征:提高步频时,触地时间(P<0.05)和腾空时间(P<0.01)减小,而触地时间/腾空时间增加(P<0.05);自选步频+5%时,膝关节蹬伸幅度减小3°至4°(P<0.05);自选步频+10%时,膝关节蹬伸幅度减小3°至4°(P<0.05),髋关节蹬伸幅度减小3°(P<0.05),膝关节前摆幅度减少4°(P<0.01);步频降低时,触地时间和腾空时间逐渐增加,而触腾比减小(P<0.05);触地时间(r=-0.71,P<0.01)和触地时间/腾空时间(r=-0.67,P<0.01)与摄氧量呈负相关关系,腾空时间与摄氧量呈正相关关系(r=0.65,P<0.01);④结果说明,虽然即刻提高个人步频未发现有能量节省化效果,这可能需要长期的训练或适应,但从研究人群来看,以更小的步幅及更大的步频/步幅比值跑步时,对应的能量消耗更低。在缩短步幅跑步时,触地腾空时间比例升高,髋关节和膝关节动作幅度变小,能使跑步的动作更加平稳,膝关节负荷减小。

摘要：Anthocyanins have high antioxidant activities, and engineering of anthocyanin biosynthesis in staple crops, such as rice （Oryza sativa L.）, could provide health-promoting foods for improving human health. However, engineering metabolic pathways for biofortification remains difficult, and previous attempts to engineer anthocyanin production in rice endosperm failed because of the sophisticated genetic regulatory network of its biosynthetic pathway. In this study, we developed a high-efficiency vector system for transgene stacking and used it to engineer anthocyanin biosynthesis in rice endosperm. We made a construct containing eight anthocyanin-related genes （two regulatory genes from maize and six structural genes from Coleus） driven by the endosperm-specific promoters,plus a selectable marker and a gene for marker excision. Transformation of rice with this construct generated a novel biofortified germplasm ＂Purple Endosperm Rice＂ （called ＂Zijingmi＂ in Chinese）, which has high anthocyanin contents and antioxidant activity in the endosperm. This anthocyanin production results from expression of the transgenes and the resulting activation （or enhancement） of expression of 13 endogenous anthocyanin biosynthesis genes that are silenced or expressed at low levels in wild-type rice endosperm. This study provides an efficient, versatile toolkit for transgene stacking and demonstrates its use for successful engineering of a sophisticated biological pathway, suggesting the potential utility of this toolkit for synthetic biology and improvement of agronomic traits in plants.

摘要：通过对核心低温器件进行低温参数测试的方式进行选型和设计,制作了一款MMIC集成结构的Ka频段低温限幅放大器,测试结果表明,在物理环境温度20 K下,工作频带32 GHz~38 GHz范围内,其噪声温度T_(e)≤73 K,增益≥16.8 dB,限幅耐功率电平≥2 W,能够有效提升接收机系统灵敏度和抗烧毁能力。

摘要：超导接收机的真空寿命决定着整个系统的性能指标和可靠性,杜瓦的长寿命高真空保持至关重要,超导接收机的杜瓦相对于红外杜瓦及大型的低温接收机杜瓦有许多新的不同和难点。本文介绍了在小型超导接收机杜瓦真空设计以及工艺过程方面的一些经验做法,包括杜瓦内部材料选型、材料清洗及预排气处理、焊接及排气过程控制等方面的设计要求,通过实验数据分析估算了杜瓦真空寿命时间,能够满足工程使用要求。