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131.
Due to unprecedented features including high‐energy density, low cost, and light weight, lithium–sulfur batteries have been proposed as a promising successor of lithium‐ion batteries. However, unresolved detrimental low Li‐ion transport rates in traditional carbon materials lead to large energy barrier in high sulfur loading batteries, which prevents the lithium–sulfur batteries from commercialization. In this report, to overcome the challenge of increasing both the cycling stability and areal capacity, a metallic oxide composite (NiCo2O4@rGO) is designed to enable a robust separator with low energy barrier for Li‐ion diffusion and simultaneously provide abundant active sites for the catalytic conversion of the polar polysulfides. With a high sulfur‐loading of 6 mg cm?2 and low sulfur/electrolyte ratio of 10, the assembled batteries deliver an initial capacity of 5.04 mAh cm?2 as well as capacity retention of 92% after 400 cycles. The metallic oxide composite NiCo2O4@rGO/PP separator with low Li‐ion diffusion energy barrier opens up the opportunity for lithium–sulfur batteries to achieve long‐cycle, cost‐effective operation toward wide applications in electric vehicles and electronic devices.  相似文献   
132.
Herein, a new P2‐type layered oxide is proposed as an outstanding intercalation cathode material for high energy density sodium‐ion batteries (SIBs). On the basis of the stoichiometry of sodium and transition metals, the P2‐type Na0.55[Ni0.1Fe0.1Mn0.8]O2 cathode is synthesized without impurities phase by partially substituting Ni and Fe into the Mn sites. The partial substitution results in a smoothing of the electrochemical charge/discharge profiles and thus greatly improves the battery performance. The P2‐type Na0.55[Ni0.1Fe0.1Mn0.8]O2 cathode delivers an extremely high discharge capacity of 221.5 mAh g?1 with a high average potential of ≈2.9 V (vs Na/Na+) for SIBs. In addition, the fast Na‐ion transport in the P2‐type Na0.55[Ni0.1Fe0.1Mn0.8]O2 cathode structure enables good power capability with an extremely high current density of 2400 mA g?1 (full charge/discharge in 12 min) and long‐term cycling stability with ≈80% capacity retention after 500 cycles at 600 mA g?1. A combination of electrochemical profiles, in operando synchrotron X‐ray diffraction analysis, and first‐principles calculations are used to understand the overall Na storage mechanism of P2‐type Na0.55[Ni0.1Fe0.1Mn0.8]O2.  相似文献   
133.
Climate change refugia in the terrestrial biosphere are areas where species are protected from global environmental change and arise from natural heterogeneity in landscapes and climate. Within the marine realm, ocean acidification, or the global decline in seawater pH, remains a pervasive threat to organisms and ecosystems. Natural variability in seawater carbon dioxide (CO2) chemistry, however, presents an opportunity to identify ocean acidification refugia (OAR) for marine species. Here, we review the literature to examine the impacts of variable CO2 chemistry on biological responses to ocean acidification and develop a framework of definitions and criteria that connects current OAR research to management goals. Under the concept of managing vulnerability, the most likely mechanisms by which OAR can mitigate ocean acidification impacts are by reducing exposure to harmful conditions or enhancing adaptive capacity. While local management options, such as OAR, show some promise, they present unique challenges, and reducing global anthropogenic CO2 emissions must remain a priority.  相似文献   
134.
Conservation genetics is a well‐established scientific field. However, limited information transfer between science and practice continues to hamper successful implementation of scientific knowledge in conservation practice and management. To mitigate this challenge, we have established a conservation genetics community, which entails an international exchange‐and‐skills platform related to genetic methods and approaches in conservation management. First, it allows for scientific exchange between researchers during annual conferences. Second, personal contact between conservation professionals and scientists is fostered by organising workshops and by popularising knowledge on conservation genetics methods and approaches in professional journals in national languages. Third, basic information on conservation genetics has been made accessible by publishing an easy‐to‐read handbook on conservation genetics for practitioners. Fourth, joint projects enabled practitioners and scientists to work closely together from the start of a project in order to establish a tight link between applied questions and scientific background. Fifth, standardised workflows simplifying the implementation of genetic tools in conservation management have been developed. By establishing common language and trust between scientists and practitioners, all these measures help conservation genetics to play a more prominent role in future conservation planning and management.  相似文献   
135.
Modifications of the Illinois River and associated tributaries have resulted in altered hydrologic cycles and persistent river‐floodplain connections during the growing season that frequently impede the establishment of hydrophytic vegetation and have reduced value for migratory waterfowl and other waterbirds. To help guide floodplain restoration, we compared energetic carrying capacity for waterfowl in two wetland complexes along the Illinois River under different management regimes during 2012–2015. The south pool of Chautauqua National Wildlife Refuge (CNWR) was seasonally flooded due to a partial river connection and managed for moist‐soil vegetation. Emiquon Preserve was hydrologically isolated from the Illinois River by a high‐elevation levee and managed as a semipermanently flooded emergent marsh. Semipermanent emergent marsh management at Emiquon Preserve produced 5,495 energetic use‐days (EUD)/ha for waterfowl and other waterbirds across wetland cover types and years, and seasonal moist‐soil management at CNWR produced 6,199 EUD/ha in one of 4 years. At Emiquon Preserve, the aquatic bed cover type produced 9,660 EUD/ha, followed by 5,261 EUD/ha in moist‐soil, 1,398 EUD/ha in persistent emergent, 1,185 EUD/ha in hemi‐marsh, and 12 EUD/ha in open water cover types. At CNWR, the annual grass and sedge cover type produced 7,031 EUD/ha, followed by 5,618 EUD/ha in annual broadleaf and 1,305 EUD/ha in perennial grass cover types. Restoration of floodplain wetlands in isolation from frequent flood pulses during the growing season can produce hemi‐marsh and aquatic bed vegetation communities that provide high‐quality habitat for waterfowl and which have been mostly eliminated from large river systems in the Midwest, U.S.A.  相似文献   
136.
An absolute environmental sustainability assessment (AESA) addresses whether a production or consumption activity can be considered environmentally sustainable in an absolute sense. This involves a comparison of its environmental pressure to its allocated environmental carrying capacity. AESA methods have been developed in multiple academic fields, each using their own set of concepts and terms with little communication across the fields. A recent growing interest in using AESA methods for decision support calls for a better common understanding of the constituents of an AESA method and how it can be communicated to scientific peers and to potential users. With this aim, we develop a framework for AESA methods, composed of a succession of four assessment steps and involving six methodological choices that must be made by the method developer or the user. We then use the framework to analyze and compare five selected AESA methods that focus on the release of phosphorus and nitrogen to the environment. In this manner, we show that the framework is able to systematically differentiate AESA methods that initially appear to be similar. Intended users of the framework include (1) method developers communicating new AESA methods to academic peers or potential method users and (2) researchers comparing a group of existing AESA methods and communicating their differences to their peers and to potential users looking for guidance on method selection.  相似文献   
137.
Human impact is near pervasive across the planet and studies of wildlife populations free of anthropogenic mortality are increasingly scarce. This is particularly true for large carnivores that often compete with and, in turn, are killed by humans. Accordingly, the densities at which carnivore populations occur naturally, and their role in shaping and/or being shaped by natural processes, are frequently unknown. We undertook a camera-trap survey in the Sabi Sand Game Reserve (SSGR), South Africa, to examine the density, structure and spatio-temporal patterns of a leopard Panthera pardus population largely unaffected by anthropogenic mortality. Estimated population density based on spatial capture–recapture models was 11.8 ± 2.6 leopards/100 km2. This is likely close to the upper density limit attainable by leopards, and can be attributed to high levels of protection (particularly, an absence of detrimental edge effects) and optimal habitat (in terms of prey availability and cover for hunting) within the SSGR. Although our spatio-temporal analyses indicated that leopard space use was modulated primarily by “bottom-up” forces, the population appeared to be self-regulating and at a threshold that is unlikely to change, irrespective of increases in prey abundance. Our study provides unique insight into a naturally-functioning carnivore population at its ecological carrying capacity. Such insight can potentially be used to assess the health of other leopard populations, inform conservation targets, and anticipate the outcomes of population recovery attempts.  相似文献   
138.
中国三江源国家公园与韩国智异山国家公园的对比研究   总被引:1,自引:0,他引:1  
自1967年智异山被认定为韩国首个国家公园以来,韩国以国家公园为主体的自然保护地体系建设已历经50余年。这期间韩国在国家公园的建设中积累了大量经验,十分值得我国借鉴。选取我国首个国家公园体制试点——三江源国家公园和韩国首个国家公园——智异山国家公园为研究对象,对二者的管理现状进行了定性分析,并运用基于最优实践的国家公园管理能力评价方法对二者的管理能力进行了定量评价。研究表明:三江源国家公园的管理能力综合得分低于智异山国家公园,在体制建设、保障机制、资源环境管理、社区管理和科普教育五个方面均与智异山国家公园存在一定差距;智异山国家公园在资源本底调查、法制建设、多方参与、环境教育和游憩管理方面的管理能力十分突出,为三江源国家公园管理能力的提升提供了有益借鉴;三江源国家公园在生态补偿和制度约束方面具有比较优势,但在自然资源权属、资源本底调查、社区组织建设和游憩管理方面则亟待提升。在此基础上,针对三江源国家公园建设提出了强化科研支撑、健全多方参与制度、推进全民福利共享三项建议,针对我国国家公园体制建设提出了制定《国家公园法》、设置自然保护地顶层规划两项建议,以期促进三江源国家公园管理能力提升、推动我国国家公园体制建设。  相似文献   
139.
城市边缘区生态承载力时空分异研究——以甘井子区为例   总被引:1,自引:0,他引:1  
裴鹰  杨俊  李冰心  李雪铭  葛雨婷 《生态学报》2019,39(5):1715-1724
以大连市甘井子区为例,利用1998年的土地利用数据和2003年、2007年、2013年的SPOT5遥感数据等多元数据,运用状态空间表征生态承载力量值的计量方法,计算了城市边缘区的社区生态承载力,并研究了甘井子区1998—2013年生态承载力的时空分异特征。结果表明:(1)时间上,1998—2013年,甘井子区整体的生态承载力呈现先快后慢的下降趋势,生态状态呈现出从优秀向良好,再向一般过渡的阶段特征。(2)空间上,甘井子区整体的生态承载力等级东西部差异明显,呈现出相同承载力等级小范围聚集和相近承载力等级间穿插分布的特征。(3)甘井子区内部各社区生态承载力程度差异明显。靠近市区的社区生态承载力15年间变化显著,生态承载程度迅速下降,远离市区的部分社区生态承载力变化不大,生态环境保持良好以上的状态。  相似文献   
140.
张萌 《人类学学报》2019,38(1):60-76
尼安德特人和解剖学意义上的现代人在文化精致程度上的区别已经争论了很长时间,考古学者希望能得出一个确定的答案,两个假设应运而生:智力水平(尼人不能发展出精致的文化)与文化表现(尼人不需要发展出精致程度较高的文化)。古人类与考古材料显示智力水平假设有缺陷:尼人的基因进入了现代人的基因库中,而且他们有能力学习现代人的技术,在"过渡工业"的材料中可以找到相关证据;与此同时,至今还未找到关系到智力水平的大脑结构证据证明尼人智力水平不如现代人。检验文化表现假设的前提是尼人与早期现代人在智力水平上没有差异,却呈现出不同的社会网络和社会组织。本文在讨论尼人与现代人人口与社会交流的基础上,认为现代人复杂的社会组织切割了尼人的生活环境,同时火山爆发引起了资源短缺,最终导致了尼人在欧洲灭绝。  相似文献   
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