摘要：建立了全自动在线顶空固相微萃取-气相色谱-质谱联用(HS-SPME-GC-MS)分析法同时测定生活饮用水中2-氯酚、2,4-二氯酚、2,4,6-三氯酚和五氯酚.通过单因素实验设计考察了萃取纤维、萃取温度、萃取时间、加盐量、加酸量、消毒剂余量等对萃取效果的影响.优化后的顶空固相微萃取条件为:取10 mL水样于20 mL顶空瓶中,加入3.6 g NaCl、0.1 mL 1 mol·L^(−1)盐酸溶液,使用65μm DVB/PDMS纤维头,萃取温度60℃,萃取时间60 min,振摇速率450 r·min^(−1),解吸时间5 min,解吸温度280℃.4种氯酚浓度-响应线性关系良好,相关系数r均大于0.9994,方法检出限为0.015—0.060μg·L^(−1),方法定量限为0.050—0.20μg·L^(−1),平均回收率为90.4%—115%,相对标准偏差为0.47%—6.91%.该方法具有准确、便捷、灵敏度高等优点,适用于生活饮用水中多种氯酚的同时测定.

摘要：当前小学数学概念教学面临多重挑战,包括教学资源的单一模态呈现、学生在概念掌握上的个体差异、教学方法的枯燥乏味、缺乏互动性等问题。利用生成式人工智能整合跨模态资源、设计个性化学习路径和创建虚拟助教以促进深度对话,理论上能够有效弥补传统数学课堂教学的不足。通过探讨将生成式人工智能应用于小学数学概念教学的可能性,提出一个优化和重构教学过程的框架。该框架覆盖教学前、教学中和教学后三个阶段。尽管生成式人工智能在辅助小学数学概念教学中展现出诸多优势,但也必须认识到其技术局限性和潜在弊端。因此,生成式人工智能应被视为教学辅助工具而非替代品。教师应根据学生的实际需求和学习情况,合理融合传统与现代教学资源和方法,以确保教学的有效性和学生学习的全面性。通过这种方式,能够最大化地发挥生成式人工智能在教育中的积极作用,同时避免其潜在的负面影响。

摘要：新疆美术作为中国美术的重要组成部分,是中华文化的视觉载体之一。文本通过回顾新疆美术创作的发展历程,指出新疆本土画家始终关注时代、关注社会,强化视觉艺术符号在文化认同层面的正向导引作用,形成情景交融的抒情美、和谐共生的自然美、寓意丰富的装饰美和气韵生动的色彩美等新疆美术创作的美学特色。现实主义表现方式处于新疆美术创作的主导地位,一是现实主义表现方式中写实具象的绘画方式易于为人民群众接受;二是社会主义文艺的性质决定了其要为人民服务、为社会主义服务。因此,充分体现人民群众心理需求和欣赏趣味的现实主义艺术创作更能满足人民群众的精神文化需求。

摘要：Broadband sound sink/absorber via a structure with deep sub-wavelength thickness is of great and continuing interest in physics and engineering *** intuitive technique extensively used is to combine components(resonators)with quasi-perfect absorption to piece together a broad absorbing band,but the requirement of quasi-perfect absorption substantially places a very strict restriction on the impedance and thickness of the ***,we theoretically and experimentally demonstrate that a compact broadband acoustic sink that quasi-perfectly absorbs broadband arriving sound waves can be achieved with coherently coupled‘‘weak resonances"(resonant sound absorbing systems with low absorption peaks).Although each component exhibits rather low absorption peak alone,via manipulating the coherent coupling effect among the components,they collectively provide a remarkably improved performance over a wide frequency range with a significantly compressed *** illustrate the design principle,a hybrid metasurface utilizing the coaction of parallel and cascade couplings is presented,which possesses an average absorption coefficient of 0.957 in the quasi-perfect band(a>0:9)from 870 to 3224 Hz with a thickness of only 3.9 *** results open new avenues for the development of novel and highly efficient acoustic absorbers against low frequency noise,and more essentially,suggest an efficient approach towards on-demand acoustic impedance engineering in broadband.

摘要：The solid-state magnetic cooling(MC)method based on the magnetocaloric effect(MCE)is recognized as an environmentally friendly and high-energy-efficiency *** search or design of suitable magnetic materials with large MCEs is one of the main targets at *** this work,we apply the chemical and hydrostatic pressures in the Ni_(35)Co_(15)Mn_(35-x)Fe_(x)Ti_(15) all-d-metal Heusler alloys and systematically investigate their crystal structures,phases,and magnetocaloric performances experimentally and *** the alloys are found to crystallize in an ordered B2-type structure at room temperature and the atoms of Fe are confirmed to all occupy at sites Mn(B).The total magnetic moments decrease gradually with increasing Fe content and decreasing of volume as *** martensitic transformation temperature decreases with the increase of Fe content,whereas increases with increasing hydrostatic ***,obviously enhanced magnetocaloric performances can also be obtained by applied *** maximum values of magnetic entropy change and refrigeration capacity are as high as 15.61(24.20)J(kg K)^(−1) and 109.91(347.26)J kg^(−1) withΔH=20(50)kOe,*** magnetocaloric performances are superior to most of the recently reported famous materials,indicating the potential application for active MC.

摘要：Background:It is not completely clear whether a very high pre-therapy viral load(≥500000 copies/ml)can impair the virological *** aim of this study was to examine the influence of very high baseline HIV-RNA levels on long-term virological responses under one type of ***:A retrospective study was performed based on data from two multicenter cohorts in China from January to November 2009,and from May 2013 to December *** HIV infected adults between 18 and 65 years old were recruited before receiving non-nucleoside reverse transcriptase inhibitor-based *** patients had baseline HIV-RNA levels over 500 copies/ml,good adherence,and were followed for at least 24 *** suppression was defined as the first HIV-RNA<50 copies/*** failure was defined as any of incomplete viral suppression(HIV-RNA≥200 copies/ml without virological suppression within 24 weeks of treatment)and viral rebound(confirmed HIV-RNA level≥50 copies/ml after virological suppression).Chi-square test,Kaplan–Meier analysis,Cox proportional hazards model and Logistic regression were used to compare virological response between each pretreated viral load ***:A total of 758 treatment-naïve HIV patients in China were *** follow-up time(IQR)was 144(108–276)*** week 48,rates of virological suppression in three groups(<100000,100000–500000 and≥500000 copies/ml)were 94.1,85.0,and 63.8%,respectively(P<0.001).Very high baseline HIV viremia over 500000 copies/ml were found to be associated with delayed virological suppression(≥500000 vs<100000,adjusted relative hazard=0.455,95%CI:0.32–0.65;P<0.001)as well as incomplete viral suppression(≥500000 vs<100000,adjusted odds ratio[aOR]=6.084,95%CI:2.761–13.407;P<0.001)and viral rebound(≥50000 vs<100000,aOR=3.671,95%CI:1.009–13.355,P=0.048).Conclusions:Very high levels of pre-treatment HIV-RNA were related with delayed efficacy of NNRTI-based ART and increased risk of treatment failure.

摘要：The influence of labyrinth seal structure parameters and their interaction on the characteristics of leakage amount are numerically investigated by conducting a quadratic regression orthogonal experiment. To determine the optimal structure parameters of the steam seal for minimizing the leakage amount, a reliable regression equation that does not lack of fit is established. The flow characteristics of the fluid in the labyrinth seal are analyzed in detail. Results show that the leakage amount is greatly influenced by seal cavity depth, convex platform height, seal tooth thickness, and tooth tip clearance, with the tip clearance having the most significant effect. The interaction among the four items exerts a certain impact on the leakage amount. The proposed regression equation exhibits a good significance and does not lack of fit. After optimization, the labyrinth seal demonstrates increased entropy and energy dissipation at the tip of the seal tooth, as well as decreased speed and inertia effect in the cavity, suggesting that the resistance leakage performance of the optimized labyrinth seal is improved.

摘要：“受贿行贿一起查”的关键在于“一起查”而非绝对地“对称罚”。行贿罪、受贿罪对称性或非对称性惩治不应该是个笼统的概念,应结合构成要件、刑罚配置、量刑情节、查处程序机制等结构要素进行类型化分析,根据各结构要素背后的教义学原理进行对称性或非对称性设计。在构成要件方面,行贿罪与受贿罪的对合犯属性及权钱交易本质决定了应保持对称性。在刑罚配置方面,受贿罪的责任刑、预防刑均高于行贿罪,故配刑应保持非对称性。在量刑情节方面,基于囚徒困境理论,行贿罪特别自首制度应保留且不宜过度限制,而受贿罪特别从宽制度应废除,保持非对称性;行贿罪七种从重情节宜删除。在查处程序方面,建立并案调查、行贿人免刑司法审查等正当程序机制,确保“查”之对称性和“处”之非对称性。

摘要：具有良好吸声和机械性能的蜂窝吸声结构在航空工程领域应用广泛.微穿孔板与蜂窝型背腔相结合的复合结构是目前实现吸声降噪声衬设计的主要形式.本文所设计的声衬结构引入了内嵌管及不同腔深设计的蜂窝腔体,以亚波长的厚度实现了低频宽带的高效吸声.在理论上建立了含有内嵌管的不同深度蜂窝腔体声衬的理论模型,揭示了该构型的并联耦合吸声机制,设计了厚度为35、45和51 mm的3个吸声结构,分别在400~600、400~800、600~1600 Hz频带内实现了平均吸声系数超过0.9的高效宽频吸声.理论、仿真与实验结果吻合较好.内嵌管和腔深各异的构型为声衬设计提供了更高的自由度.该声衬轻薄简单的结构具有良好的工程应用前景.

摘要：高铁站房钢屋盖对温度敏感且超静定次数较多,在寒区低温和积雪作用下容易造成垮塌。为探究高铁站房异形屋盖结构在低温及极端雪荷载耦合作用下的力学性能,以东北某地区高铁站房为背景,采用有限元软件ABAQUS建立屋盖模型,利用现场监测数据验证了有限元模型的准确性。研究设计温差对屋盖结构的影响,考虑场址处近年极端低温天气频现,分析极端温差下屋盖受力。基于不同设计雪荷载分布方式,开展屋盖结构的受力分析,进而考虑寒区极端雪荷载,并探究极端雪荷载与极端温差耦合下的受力状态。结果表明:屋盖两侧弧形边缘部分杆件不同温差下应力变化显著,对温度变化较为敏感,极端温差下需要重视此区域内杆件应力变化;站房屋盖设计时,对于存在天窗的屋盖结构,应重视因天窗与周围屋面高度差而产生的不均匀雪荷载对结构内力的影响;极端雪荷载作用下,屋盖最大应力杆件接近屈服,最大竖向位移也接近规范容许值;考虑极端雪荷载与极端降温耦合相比设计雪荷载与设计温差耦合屋盖最大拉应力、最大下绕位移分别增大47.1%、50.2%,且应力已经超过钢材设计强度,在寒区大跨高铁站房钢屋盖设计时应充分考虑二者耦合的影响。