摘要：Ecosystems in China have been absorbing anthropogenic CO2 over the last three decades. Here, we assess future carbon uptake in China using models from phase 5 of Coupled Model Intercomparison Project under four socio-economic scenarios. The average of China's carbon sink from 2006 to 2100 represented by multimodel mean net ecosystem production(NEP) is projected to increase(relative to averaged NEP from 1976 to 2005) in the range of 0.137 and 0.891 Pg C a-1across differentscenarios. Increases in NEP are driven by increases in net primary production exceeding increases in heterotrophic respiration, and future carbon sink is mainly attributed to areas located in eastern China. However, there exists a considerable model spread in the magnitude of carbon sink and model spread tends to be larger when future climate change becomes more intense. The model spread may result from intermodel discrepancy in the magnitude of CO2 fertilization effect on photosynthesis, soil carbon turnover time, presence of carbon-nitrogen cycle and interpretation of land-use changes. For better quantifying future carbon cycle, a research priority toward improving model representation of these processes is recommended.

摘要：Electrochemical CO_(2) reduction is a promising technology for solving the CO_(2) emission problems and producing value-added products. Here, we report a hierarchically porous Cu1Au single-atom alloy(SAA) as an efficient electrocatalyst for CO_(2) reduction. Benefiting from the hierarchically porous architectures with abundant vacancies as well as three-dimensional accessible active sites, the as-prepared nanoporous Cu1Au SAA catalyst shows remarkable CO_(2) reduction performance with nearly 100% CO Faraday efficiency in a wide potential range(-0.4 to -0.9 V vs. reversible hydrogen electrode. The in-situ X-ray absorption spectroscopy studies and density functional theory calculations reveal that the Cu-Au interface sites serve as the intrinsic active centers,which can facilitate the activated adsorption of CO_(2) and stabilize the *COOH intermediate.

摘要：Laser additive manufacturing technology with powder feeding was employed to repair wrought Ti17titanium alloy with small surface *** microstructure,micro-hardness and room temperature tensile properties of laser additive repaired(LARed)specimen were *** results show that,cellular substructures are observed in the laser deposited zone(LDZ),rather than the typicalαlaths morphology due to lack of enough subsequent thermal *** cellular substructures lead to lower micro-hardness in the LDZ compared with the wrought substrate zone which consists of duplex *** tensile test results indicate that the tensile deformation process of the LARed specimen exhibits a characteristic of dramatic plastic strain heterogeneity and fracture in the laser repaired zone with a mixed dimple and cleavage *** tensile strength of the LARed specimen is slightly higher than that of the wrought specimen and the elongation of11.7%is lower.

摘要：“分类观”的建构有助于学生对物质世界形成有序的认识,并为其他化学观念的形成提供基本框架,促进学生核心素养的培养。针对学生“分类观”建构存在的困难,设计卡牌游戏并进行教学实践,不仅完成了教学目标,也让学生对化学的兴趣更加浓厚。

摘要：扩散模型变革了文本–图像生成领域,使终端用户可以基于简单的自然语言提示生成高质量、多样化的图像艺术作品.然而,由于训练数据集庞大且未经过滤,文本–图像生成模型具有生成色情内容与暴力内容等不适当内容的能力.为更加安全地部署此类模型,提出了一种基于CLIP (contrastive languageimage pre-training)方向性损失的微调(directional CLIP loss based fine-tuning, CLIF)算法,使用方向性的CLIP损失来微调模型,以抑制其生成不适当内容的能力. CLIF消耗的计算资源很少,并且具有强制生效的特点.为评估其抑制效果,提出了CTP (categorized toxic prompts)用于评估文本–图像生成模型的不适当内容生成能力.在CTP与COCO (common objects in context)上的实验结果表明, CLIF能够在抑制文本–图像扩散模型生成不安全内容的同时不影响其一般性生成能力.

摘要：近年来,由于窄带隙小分子受体的快速发展以及高性能聚合物给体不断出现,非富勒烯有机太阳能电池(NF-OSCs)取得了突破性进展,其能量转换效率(PCE)已接近20%。然而,随着D-A交替共聚聚合物材料设计逐渐饱和,迫切需要开发更高效的共轭聚合物材料。而利用无规共聚策略制备的D-A型无规共聚物具有能级易调节、有宽且强的吸收以及较高的吸光系数等优势,因此备受关注。本文首先讨论了无规D-A共聚策略在调控聚合物性质和器件性能方面的优势。其次,分别从无规聚合物给体材料和受体材料两方面综述了无规共聚策略在活性层材料的应用研究。最后,对于三元无规聚合物在有机太阳能电池中的进一步发展进行了总结与展望。

摘要：The electrochemical dissolution and passivation of laser additive manufactured Ti6Al4V were investigated through Tafel polarization,potentiostatic polarization and AC impedance *** results show that the solution treatment−aging(STA)process aggravates the element micro-segregation compared to the annealing process,leading to varied Al and V contents of the phases from different *** is proven that either Al-rich or V-rich condition can highly affect the electrochemical dissolution behaviors due to thermodynamical instability caused by element *** dissolution rate in the metastable passivation process is controlled by the stability of the produced film that is affected by phases distribution,especially the difficult-to-dissolve *** then,the dissolution rate of the phases in the transpassivation region is consistent with the rank in the activation process because the dense film is not capable of being *** to the annealed sample,the higher dissolution rate of the STA sample is beneficial to the electrochemical machining(ECM)of Ti6Al4V.

摘要：煤炭地下气化条带开采适应强,且有助于围岩稳定控制,应用前景良好。为研究地下气化热-力耦合作用下条带开采过程中燃空区围岩的温度场、应力场和位移场的演化规律,采用COMSOL Multiphysics对贵州盘江山脚树矿4号煤层地下气化条带开采进行了数值模拟,并对气化开采和常规开采后的围岩应力和变形特征进行了对比分析。结果表明:随着气化工作面推进,围岩体内部约2 m区域的温度先升高后降低,温度传导范围一直呈扩大趋势,最大影响范围为10~12 m,温度在顶板中的传导范围最大,两侧煤体次之,底板最小。地下气化高温会在燃空区围岩体中产生热应力,导致地下气化条带煤柱所受垂直应力要明显高于常规开采的,并使燃空区悬露面、煤柱与顶底板交界面均承受水平压应力。燃空区邻近区域的顶底板位移趋势与常规的相同,但顶底板深部的位移则出现相反情况,即顶板上移、底板下沉。燃空区围岩的水平位移量明显大于常规条带开采的,且开采区域的左侧围岩体向左水平移动,右侧围岩体向右水平移动。地下气化条带开采过程中直接顶变形的波动幅度明显大于常规开采的,并在有煤体支撑的区域出现上移现象,其模型顶部岩层出现了整体上移现象,且其变形量大于常规开采的,说明地下气化过程中形成的热应力能一定程度上阻止覆岩的下沉变形。数值模拟结果可为地下气化条带开采的工程设计提供理论指导。

摘要：[目的]在当前确保粮食安全和坚守18亿亩耕地红线的背景下,聚焦粮田类的农业文化遗产,力求在保护性开发的前提下,解决当前遗产保护与旅游发展之间的矛盾.[方法]以中国重要农业文化遗产名录作为数据基础,系统梳理46项粮田类农业文化遗产,通过实地调研、文献检索、案例分析的方法,分析其空间分布、类型特征与景观构成要素.[结果]粮田类农业文化遗产的生态脆弱性高,在旅游景观营造中,存在空窗期长、特色化低、传承力弱等系列问题.从保护性开发视角出发,提出多样化的提升策略:1)原真性保留,提升遗产地的景观本底,保护其生态基础;2)全场景构建,打造四季可赏的景观体系,增强持续吸引力;3)地域性营造,结合当地的自然环境和文化背景,因地制宜;4)沉浸式体验,策划互动性活动,增强游客参与感和文化认同.[结论]为农业文化遗产的旅游景观提升提供了有效路径,对推动遗产保护、乡村旅游和文化传承具有重要意义.

摘要：以2010—2019年数字经济概念上市公司为样本,探究数字经济背景下如何利用企业社会网络、知识网络双重嵌入的经济效应,实现创新绩效提升。研究结果表明,数字经济背景下,社会网络、知识网络嵌入对企业创新绩效存在显著促进作用。但数字经济减弱了“中间人”在社会网络中的重要性,“中间人”企业可以通过影响知识网络来提升创新绩效。进一步研究发现,社会网络、知识网络能有效缓解企业融资约束,从而提升创新绩效。在高信息透明度和低代理成本条件下,网络嵌入的经济效应更为显著。应加强沟通和拓展视野、提升董事和高管的学术背景、合理设计董事会成员数量、以及提高独立董事比例,为提升中国数字经济企业创新绩效提供经验借鉴。