摘要：本文系统而扼要地论述了在自然资源保护和经济持续发展中,生态学方面的先决条件。人类活动造成了环境的日益恶化,并威胁着生物圈。第三世界国家必须发展经济,否则,贫穷、饥饿和疾病将危及整个民族的生存,现行的环境持续发展的概念也许只是掩饰矛盾而并不现实。因此必须用新的战略决策使经济增长居于稳定的生态环境之中。如果把生态学原理、方法和现有的知识有效地贯彻到经济计划中,经济的持续发展就会变成现实。发展中国家试图取得经济的持续发展,必须注意以下10个必要生态条件:1.信息的传播。信息传播包括环境科学专业化训练、公众环境知识教育及有关发展计划和决策的生态学概念的诸多内容。应让决策者了解生态学理论基础;2.讲习生态系统知识。制定经济发展计划时必须认清生态系统内部、生态系统之间的相互作用,建立生态系统的概念模型以说明生态系统各组分之间的相互依赖关系;3.必须认识到生态、经济、政治和社会系统间的相互联系,人类及其社会系统是关键所在;4.设计生态系统的经济模型,为决策者提供自然资源的有关信息;5.使自然资源从消耗性利用向非消耗性利用转变;6.加强和下放权力,强制执行环境政策和法规;7.简化有关环境法规,开明地应用环境评价方法。政策与法规不应当超出政府的能力范围,并考虑?

摘要：A newly designed TiAl alloy containing W,Nb,and B was produced through magnetic-flotation-melting *** production of this TiAl-based alloy,15 kg ingot size,which is quite different from the 0.05 kg small ingot produced by arc-melting,has a large effect on the metallurgical properties,such as the grain size and the phase structures of the *** treatments were carefully designed in order to reduce the amount of the high-temperature remaining β phase in the alloy,and to obtain optimal microstructures for mechanical behavior studies.A room-temperature ductility of 1.9% was obtained in the cast TiAl-based alloy after the appropriate heat *** mechanical behavior of the large ingot through mass production of the TiAl-based alloy was largely improved by the alloy design and subsequent heat treatments.

摘要：背景:通过对人工关节无菌性松动发病机制的深入研究已证实,单核巨噬细胞、成纤维细胞、成骨细胞等在磨损微粒刺激下会产生大量炎性破骨细胞因子,导致假体周围骨溶解。另有研究发现细菌内毒素在人工关节无菌性松动中可能起重要作用。目的:分析人工关节磨损钛微粒诱导溶骨的分子生物学机制。设计、时间及地点:对比观察实验,于2004/2008在武汉大学人民医院和田纳西州立大学医学中心完成。材料:IC-21巨噬细胞购自ATCC TIB-186 American Type Culture Collection,钛微粒购自Alfa Aesar Company,细菌内毒素购自Sigma。方法:IC-21巨噬细胞分别与清洁钛微粒、细菌内毒素结合钛微粒和细菌内毒素联合培养,作为清洁钛微粒组、细菌内毒素结合钛微粒组及细菌内毒素组,与单纯IC-21巨噬细胞组作为对照。主要观察指标:每组分别在培养4,8,16,32h各时点取巨噬细胞,分别用反转录聚合酶链反应技术和电泳迁移率变动分析法,分别检测核激活因子受体mRNA、骨保护素mRNA表达及核转录因子κBDNA的结合活性。结果:与对照组比较,细菌内毒素结合钛微粒组和清洁钛微粒组IC-21巨噬细胞培养4h时核激活因子受体mRNA表达开始增加,之后逐渐升高(P<0.01);培养8h时骨保护素mRNA表达轻度增高,随后恢复到对照组水平。细菌内毒素组未检测到核激活因子受体mRNA表达,培养4h时骨保护素mRNA表达轻度一过性增加。细菌内毒素组和细菌内毒素结合钛微粒组培养4h即可发现核转录因子κBDNA结合活性较清洁钛颗粒组显著增高(P<0.01),在培养8h达到高峰,并在随后的32h中维持在较高活性。清洁钛颗粒组培养16,32h检测到核转录因子κBDNA结合活性轻度增高,显著高于对照组(P<0.05)。结论:清洁钛微粒和细菌内毒素具有不同的诱导溶骨的作用机制。清洁钛微粒可能通过核激活因子受体/骨保护素信号途径,启动溶骨反应过程;细菌内毒素则启动核转录因子κB/破骨性细胞因子信号通路,诱导溶骨。两种机制在人工关节松动过程中同时发生,并协同作用。

摘要：Each conventional alloy has its own specific compositions but the compositional origin is largely unknown due to our insufficient understanding about chemical shortrange ordering in the alloy,in particular,in the solid-solution *** the present paper,the compositions of metallic alloys are discussed and formulated,by unveiling the basic moleculelike structural units in solid *** oscillation theory,which describes the partial charge screening behavior in solid solutions,and henceforth the origin of short-range ordering,is applied to pin down the ideal chemical compositions of conventional metallic *** propose that,at a specific composition,atoms self-assemble into an ideally ordered structure consisting of atoms residing in the nearestneighbor shell(denoted as cluster)plus those in the next outer shell(denoted as glue atoms),which can be formulated as[cluster](glue atoms).This simplified version of short-rangeorder structure represents the smallest charge-neutral and mean-density zone(termed as“chemical units”)and can be regarded as the‘molecules’of solid ***,the chemical units and the corresponding molecule-like formulas for face-centered-cubic(FCC),hexagonal close-packed(HCP),and body-centered cubic(BCC)structures are analyzed and equations are obtained to identify the chemical formulas for FCC solid *** instance,well-knownα-brass Cu-30 Zn alloy is formulated as[Zn-Cu_(12)]*** of aluminum alloys,superalloys and stainless steels are also illustrated,demonstrating the versatility of the present model to interpret chemically complex alloys.

摘要：Solar-driven steam generation is a practical strategy to harness solar energy for desalination and production of clean water with a minimized carbon ***,this strategy suffers from a low evaporation rate under weak illumination on cloudy days or at ***,we present a fabric-based all-weather-available photo-electrothermal steam generator(P/ET-SG)capable of regulating the surface temperature and evaporation rate by the coupling effect of photo-thermal and electro-thermal heating depending on the light *** unprecedented high surface temperature of 52℃ in the wet state and an evaporation rate of 2.61 kg m^(-2) h^(-1) were achieved by the P/ET-SG under 1 sun with only 1 V input voltage owing to the uniform heat distribution and the coupled electro-thermal *** oneway fluidic design of the P/ET-SG effectively prevented salt precipitation during continuous desalination in 24 h and was able to remove salt granules from the evaporation ***,the P/ET-SG demonstrated a high evaporation rate of 2.58 kg m^(-2) h^(-1) in the purification of concentrated saline water and dye-contaminated water with high efficiency(>99.9%).This study offers new thoughts for the design of allweather-available solar steam generators with high efficiency and makes a step forward towards fast purification of concentrated saline water and wastewater.

摘要：在分级认知无线网络中,无论何时当授权频段未被主用户占用时,次用户都可以采取机会式的方式进行接入.如何保证次用户在整个数据包传输过程中的服务质量,分析其相应传输时延性能,是目前对此类认知无线网络的研究中,一个非常值得关注的话题.集中分析了次用户系统的传输时延性能,并设计了共享多个授权信道情况下的最优接入策略.主用户和次用户系统首先各自被建模成为M/G/1排队模型.然后,将每个授权信道上主用户数据包和次用户数据包传输融合在一起进行讨论,提出一种虚拟的优先级队列模型.基于M/G/1抢占重传优先级排队理论,获得了次用户数据包传输的系统时延均值表达式.同时,基于该系统时延性能均值,讨论了共享多个授权信道的条件下的多信道接入策略设计.其被等效为一个非线性规划问题,通过经典的遗传算法,可以得到相应的全局最优解.数值结果验证了我们理论分析和接入策略设计的正确性.考虑到遗传算法的时间复杂度过高,并为了降低相应的时间开销,在实际应用中也可以采用反比例接入策略得到其近似最优解.

摘要：Plants adapt to their changing environments by sensing and responding to physical,biological,and chemical *** to their sessile lifestyles,plants experience a vast array of external stimuli and selectively perceive and respond to specific *** repurposing the logic circuitry and biological and molecular components used by plants in nature,genetically encoded plant-based biosensors(GEPBs)have been developed by directing signal recognition mechanisms into carefully assembled outcomes that are easily *** allow for in vivo monitoring of biological processes in plants to facilitate basic studies of plant growth and *** are also useful for environmental monitoring,plant abiotic and biotic stress management,and accelerating design-build-test-learn cycles of plant *** the advent of synthetic biology,biological and molecular components derived from alternate natural organisms(e.g.,microbes)and/or de novo parts have been used to build *** this review,we summarize the framework for engineering different types of *** then highlight representative validated biological components for building plant-based biosensors,along with various applications of plant-based biosensors in basic and applied plant science ***,we discuss challenges and strategies for the identification and design of biological components for plant-based biosensors.

摘要：植物细胞壁复杂的化学物理结构形成生物质抗降解屏障,严重阻碍了生物质材料的转化利用。本研究选用三种不同抗降解特性的自然变异杂交杨木,采用复合溶剂体系对原料木质素、半纤维素和纤维素进行萃取分离。利用FTIR和XRD表征样品萃取分离前后微观结构的变化。结果显示,2910,1420,1100,1030以及900 cm^(-1)的吸收峰为纤维素的特征峰;这些特征峰在低抗降解性样品中强度变化高于抗降解性高的样品谱图;抗降解程度低的原料萃取分离效率高、纤维素固体得率高,其萃取处理后所得纤维素结晶度最高,达到84.5%,而HR-Factionation的木质素去除率和纤维素结晶度最低,仅为77.6%和81.3%。研究结果表明,在萃取分离过程中,原料抗降解性与木质素去除率成正比,与纤维素的结晶度和可消化率成反比。

摘要：目的:从粗糙表面、多孔表面、规则刻槽表面、纤维表面、纹理结构和蛋白质层6个方面全面论述组织工程材料表面拓扑结构对细胞相容性的影响。资料来源:应用计算机检索PUBMED 1987-01/2007-01的相关文章,检索词为“bio-compatibility,bio-compatibility materials,tissueengineering,tissue engineering materials,cell-compatibility,cell-compatibility materials”,并限定文章语言种类为English。资料选择:对资料进行初审,并查看每篇文献后的引文。纳入标准:文章所述内容应与生物相容性组织工程材料相关。排除标准:重复研究或Meta分析类文章。资料提炼:共收集到74篇相关文献,32篇文献符合纳入标准,排除的42篇文献为内容陈旧或重复。符合纳入标准的32篇文献中,24篇涉及生物相容性,8篇涉及细胞相容性材料。资料综合:①关于组织工程材料与生物体的相互作用:综述了高分子组织工程材料在与生物体组织接触时发生各种各样的相互作用。指出了材料与生物体的相互作用情况决定了材料组织相容性的程度;材料对组织相容性的影响包含着微观分子水平和宏观尺度水平,而且,宏观大尺度上(包括材料表面的拓扑结构)的效应比分子尺度上发生的化学效应更为重要。②关于材料表面物理化学性质对材料细胞相容性的影响:综述了高分子材料的粗糙表面、多孔表面、规则刻槽表面、纤维表面、纹理结构和蛋白质层等材料表面的拓扑结构对材料细胞相容性的影响。指出这种影响是研究组织工程材料的生物相容性及进行组织相容性材料设计的重要内容。结论:材料表面的拓扑结构对材料的细胞相容性有着较大影响,细胞与聚合物的相互作用是评价材料细胞相容性的指标。细胞与高分子材料间短期的相互作用程度可由细胞与高分子材料表面的黏附程度来评价,而长期的相互作用可以通过检测体外培养细胞的生长情况或在体内植入高分子村料进行长期评估。

摘要：目的员工的工作投入、工作满意度、护理质量和离职意愿是医疗卫生机构绩效的关键指标。本研究旨在调查美国护士工作投入现状及关联因素,分析护士工作投入、工作满意度、感知护理质量和离职意愿之间的关系。方法采用横断面描述性研究设计。2022年3—9月,通过在线方式对美国注册护士进行调查。采用Utrecht工作投入量表(Utrecht Work Engagement Scale)测量护士工作投入状况,收集护士的一般资料,通过问题询问方式调查他们的工作满意度、感知护理质量和离职意愿。结果共有900名护士参与调查。其中,79.2%报告持有专业认证资格,59.4%在工作满意度方面得分较高或非常高,82.2%报告感知护理质量较高或非常高,但有28.4%的人表示在接下来的一年里可能或非常可能离职。护士的工作投入水平受到护士工作满意度、感知护理质量和离职意愿的影响。工作满意度高、感知护理质量高以及离职意愿更低的护士表现出更高水平的工作投入。线性回归分析显示,年龄较大、白种人并获得博士学位的护士与其同行相比,表现出更高水平的工作投入。结论本研究表明,护士的工作投入与其工作满意度、感知护理质量和离职意愿存在关联。护士的工作投入与工作满意度明显关联,护理管理者需要采取积极措施提高护士的工作满意度和留任率。