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1.
Freshwater ecosystem service is essential to human’s survival and development. Many studies have documented the spatial differences in the supply and demand of ecosystem services and proposed the concept of ecosystem services flows. However, few studies characterize freshwater ecosystem service flow quantitatively. Therefore, our paper aims to quantify the effects of freshwater ecosystem service flow on downstream areas. We developed a freshwater ecosystem service flow model and applied it in the Beijing–Tianjin–Hebei (BTH) region, China, for the year of 2000, 2005, and 2010. We assessed the regional water security with an improved freshwater security index by integrating freshwater service provision, consumption and flow; and found that most areas of the BTH region (69.2%) were affected by upstream freshwater flows. The areas achieving water security in the region also expanded to 66.9%, 66.1%, and 71.3%, which were 6.4%, 6.8% and 5.7% increments compared to no-flow situation, in 2000, 2005 and 2010, respectively. Setting quota for human water consumption is suggested to further improve water security. These results highlight the need to fully understand the connections between distant freshwater ecosystem service provision and local freshwater ecosystem service consumption. This approach may also help managers to choose more sustainable strategies for critical freshwater resource management across different regions.  相似文献   
2.
This study estimates the economic values of and the dominant contributors to five key ecosystem services of wetlands in Beijing, by using the wetland inventory data in 2014 and economic valuation methods. Results indicate that the 51,434 ha of wetlands in Beijing annually provide 2.07 billion m3 of flood regulation, 944.01 million m3 of water provision, 42,154 tons of chemical oxygen demand (COD) purification, 3.03 PJ of heat absorption, and 9587 ha of habitat. Their economic values are estimated to be 15.89 billion RMB, 1.19 billion RMB, 169 million RMB, 421 million RMB, and 1.08 billion RMB in 2014 (RMB: Chinese currency, US$1 = RMB 6.14), respectively. The total values of five key wetland ecosystem services reach 18.76 billion RMB. In addition, the reservoir and river wetlands in Miyun, Yanqing, Fangshan, Huairou, and Mentougou Districts contribute 78% of key ecosystem services, whereas the urban wetlands in Xicheng, Dongcheng, Haidian, Chaoyang, and Tongzhou Districts more conveniently serve densely local people, hence they should be given particular attentions. In this paper, we develop the valuation methods of wetland ecosystem services, and recommend diversified strategies, regulations, and programs to protect the remaining wetlands in Beijing. This work can also provide a reference for the valuating of wetland ecosystem services for other urban-rural areas.  相似文献   
3.
A new assay procedure for phenol sulfotransferase which employs [35S]-3'-phosphoadenosine-5'-phosphosulfate as a sulfate donor and a variety of phenols as sulfate acceptors was developed. The appearance of the 35S-sulfated products or the disappearance of the [35S]-3'-phosphoadenosine-5'-phosphosulfate are determined simultaneously by chromatography of the assay incubation mixtures on Ecteola-cellulose columns, eluting with an NH4HCO3 step gradient. Various acidic, neutral, and basic phenols can be employed as substrates for phenol sulfotransferase using this procedure.  相似文献   
4.
Human mononuclear phagocyte (M phi) populations were compared to adult human endothelial cells (HEC) for their respective abilities to influence the proliferative responses of purified human T lymphocytes to the mitogenic agents Na-m-periodate (IO-4), soybean agglutinin (SBA), or allogeneic cells. HEC and M phi were both capable of inducing proliferative responses of allogeneic T lymphocytes in mixed-lymphocyte culture. Under low cell density culture conditions, purified T-lymphocyte proliferative responses to IO-4 or SBA could be restored by addition of syngeneic M phi or HEC. At higher cell density culture conditions, proliferation of T cells to IO-4 could be amplified more by HEC than M phi. T-lymphocyte proliferative responses to SBA were amplified by addition of HEC but were suppressed by addition of M phi. These findings indicate that human adult HEC are unique and potent accessory cells for T lymphocytes. Furthermore, these findings demonstrate that accessory cell functions of HEC can be discriminated from those of M phi.  相似文献   
5.
The role of progesterone (P) as an androgen antagonist in Mongolian gerbil territorial marking was assessed in the present investigation. Twenty-seven mature males were observed for two consecutive weeks in a marking apparatus. On the basis of the average of the two sessions, subjects were matched and assigned to one of three groups. All animals were orchidectomized and tested three weeks after surgery. Three days after a single postoperative session a schedule of hormonal replacement was initiated. Group 1 was administered 640 μg testosterone propionate (TP). Group 2 received 640 μg TP followed immediately by 3 mg P. A third group received 640 μg TP followed by a 1 mg injection of P. Subjects were tested for marking 24 hr after the injection for a cumulative period of 6 wk.Results indicated that (a) castration drastically reduced marking; (b) TP alone and TP + 1 mg P restored the behavior; (c) TP + 3 mg P inhibited its restoration; and (d) a significant interaction was present between hormonal therapy and the 6-wk testing interval. However, all three hormonal treatments restored sebaceous gland dimensions. Results are discussed in terms of a model of hormone-gene action.  相似文献   
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7.
Alkyl mercaptide complexes of both synthetic and natural-derivative iron(II) porphyrins have been characterized in DMSO solution by proton nmr spectroscopy. A single mercaptide ligand binds to form a high-spin iron(II) complex as determined by solution magnetic measurements and the nmr isotropic shift pattern. Ligand exchange is slow on the nmr time scale unlike corresponding 2-methyl imidazole exchange rates which are very rapid. Further comparison of mercaptide and 2-methyl imidazole adducts reveals a downfield bias in isotropic shift values for the mercaptide species, which may be explained by different signs in the dipolar shift term for the two complexes. This apparent magnetic anisotropy of the mercaptide complex is in the same direction, although smaller, than that observed for bacterial cytochrome P-450. Isotropic shift values of at least 250 ppm for methylene resonances of the coordinated mercaptide support a very efficient unpaired spin delocalization for this axial ligand.  相似文献   
8.
BackgroundFaculty vitality is the main ingredient to enhance professional education and competence. Enriching the faculty vitality in key domains of teaching, assessing, research, professionalism, and administration is perceived to improve educational environment significantly and enhances the academic performance of learners. Faculty development program (FDP) has been considered as a stand-alone educational pedagogy in fostering knowledge and professional skills of faculty. However, few studies have provided objective reports about the impact of such programs in a healthcare system.MethodsThis research was conducted by selecting data sources of PubMed-Medline, Wiley online library, Cochrane library, Taylor & Francis Online, CINAHL, Springer link, Proquest, ISI Web of knowledge, ScienceDirect, EJS, EBSCO, Blackwell, Emerald and ABI Inform. This search followed a step-wise approach defined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A total of 37 studies that explored the impact of FDPs on medical and allied health faculty’s professional development were selected.ResultsThis meta-analysis reported a mean effect size of 0.73 that reflects a significant and positive impact of FDPs in enhancing faculty’s knowledge and professional competence (z-statistics of 4.46 significant at p-value < 0.05) using the random effects model and forest plot.ConclusionThis article reiterates the incorporation of FDPs in all healthcare institutions for improving the academic performance of faculty with resultant enrichment of learners’ knowledge and skills.  相似文献   
9.
卢洁  焦胜  胡加琦  蔡勇  欧林之 《生态学报》2023,43(15):6332-6344
城市化背景下人类与自然环境的矛盾呈现出多尺度、层级化特征,而传统生态网络的构建方式较少考虑不同尺度下生态要素的关系,无法从区域落实到中心城区,难以形成系统性的解决方案。研究在综合梳理各尺度生态网络构建方法的基础上,以长沙市为例,基于形态学空间格局分析(Morphological Spatial Pattern Analysis,MSPA)、景观连通性原理和生态斑块重要性评价识别生态源地,并通过多层级生态阻力面的确定,综合运用最小费用路径(Least-cost path method,LCP)、电路理论、层级传导理论、尺度嵌套等方法对市域、都市区、中心城区的生态网络进行了协同构建和层级优化,最后基于不同尺度生态网络的特点应用并落实到多层级的国土空间规划体系中。研究结果表明:(1)长沙市域生态网络和都市区生态网络具有较好的层级嵌套特征;共识别两尺度生态叠合源地14个、生态叠合廊道15条,主要通过中心城区内的湘江、浏阳河和捞刀河部分河段与外围生态绿圈相衔接,形成"外环内楔"的空间格局。(2)确定市域重要廊道、市域潜在廊道、生态叠合廊道、都市区重要廊道、都市区潜在廊道的核心保护面积共501.14 km2,并提取位于生态廊道核心保护区范围内的生态夹点和生态障碍点,以进一步落实生态保护修复策略。(3)得到具有重要生态连通功能的中心城区生态绿道长度441.2 km,生态修复单元56个,并结合生态阻力值划分为5级进行针对性修复。(4)基于不同尺度生态网络的衔接、嵌套,最终构建"市域总体生态安全格局-都市区城市生态空间发展格局-以城市绿道为基础的中心城区生态修复单元",并与不同层级的国土空间规划体系相对应。研究结果将为以大城市为中心的跨尺度生态系统修复和生态安全格局构建提供科学参考。  相似文献   
10.
城市扩张过程中建设用地景观格局演变特征及其驱动力   总被引:3,自引:0,他引:3  
车通  李成  罗云建 《生态学报》2020,40(10):3283-3294
剖析城市扩张过程中建设用地景观格局演变特征及其驱动力,不仅有助于城市生态环境问题的解决,而且为城市用地结构优化、城市景观规划等工作提供科学依据。以快速城市化的中型城市—扬州市为例,利用多期(1995、2000、2005、2010年和2015年)Landsat卫星影像、乡镇水平的扬州统计年鉴等数据,运用景观格局分析、增强回归树(Boosted regression trees)等方法,研究建设用地的扩张模式、形态及景观格局,定量探究地理、社会和经济因子对景观格局的影响机制,从而明晰景观格局演变特征及其驱动力。结果表明,1995—2015年,建设用地面积持续增加,填充式(Infilling)、边缘式(Edge-expansion)和跳跃式(Leapfrog)3种扩张模式在各时段均有出现,但其优势度随着城市发展而改变。建设用地的形态在城市扩张的过程中经历着"集聚"和"扩散"的交替变化过程,景观格局则出现了同质化倾向,景观破碎化下降、聚合度增加。地理因子(海拔和到县市中心的距离)对景观格局的综合影响虽然高于社会经济,但它的影响力却随着城市发展呈现出下降趋势,社会经济的作用则逐渐增强。海拔和人口密度的增加会促进景观的破碎化、抑制景观的集聚;人口数量的增加会促进景观的集聚、降低景观的破碎化;其余因子(到县市中心的距离、人均GDP和第二产业占比)的作用则随城市的发展而发生转变,如人均GDP对景观破碎化的作用表现为"促进→抑制"的转变、第二产业则为"抑制→促进"。  相似文献   
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