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971.
We model future changes in land biogeochemistry and biogeography across East Africa. East Africa is one of few tropical regions where general circulation model (GCM) future climate projections exhibit a robust response of strong future warming and general annual‐mean rainfall increases. Eighteen future climate projections from nine GCMs participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment were used as input to the LPJ dynamic global vegetation model (DGVM), which predicted vegetation patterns and carbon storage in agreement with satellite observations and forest inventory data under the present‐day climate. All simulations showed future increases in tropical woody vegetation over the region at the expense of grasslands. Regional increases in net primary productivity (NPP) (18–36%) and total carbon storage (3–13%) by 2080–2099 compared with the present‐day were common to all simulations. Despite decreases in soil carbon after 2050, seven out of nine simulations continued to show an annual net land carbon sink in the final decades of the 21st century because vegetation biomass continued to increase. The seasonal cycles of rainfall and soil moisture show future increases in wet season rainfall across the GCMs with generally little change in dry season rainfall. Based on the simulated present‐day climate and its future trends, the GCMs can be grouped into four broad categories. Overall, our model results suggest that East Africa, a populous and economically poor region, is likely to experience some ecosystem service benefits through increased precipitation, river runoff and fresh water availability. Resulting enhancements in NPP may lead to improved crop yields in some areas. Our results stand in partial contradiction to other studies that suggest possible negative consequences for agriculture, biodiversity and other ecosystem services caused by temperature increases.  相似文献   
972.
Pselaphine beetles (Coleoptera: Staphylinidae: Pselaphinae) are cosmopolitan, species‐rich, and yet poorly studied, particularly in the tropics. We sampled beetles in three types of primary forest and two types of disturbed forest habitats in eastern Thailand to assess the utility of pselaphine beetles as bioindicators of forest disturbance. We simultaneously measured leaf litter mass, soil moisture, soil acidity and canopy cover at each site to infer which environmental factors affect pselaphine beetle diversity and abundance. At each site, pselaphine beetles were extracted from ten 1 m2 samples of leaf litter and soil with Tullgren funnels. We sampled 1867 adult beetles representing six supertribes, 51 genera and 114 morphospecies; 7% of the genera and 92% of the species were undescribed. Forest types differed significantly in species richness, abundance, diversity and evenness. Primary forest had greater numbers of species and individuals, and higher diversity indices (H′). Teak plantation and secondary forest had substantially fewer individuals and species of pselaphine beetles. Species composition differed between primary and degraded forests. Canopy cover, soil moisture, and leaf litter mass positively correlated with beetle species richness and abundance. Leaf litter mass and soil moisture were the two most important factors affecting the diversity of pselaphine beetle assemblages. Among the 114 morphospecies collected, 43 morphospecies were specific to two or three habitats and 64 morphospecies were found only in a single habitat. Thus pselaphine beetles appear to have rather narrow habitat requirements and their presence/absence was correlated with environmental differences. These traits make pselaphine beetles a suitable bioindicator taxon for assessing forest litter diversity and monitoring habitat change.  相似文献   
973.
近红外光谱技术无创测量人体血糖   总被引:2,自引:0,他引:2  
人体血液中的各种化学成分一直是评价人体健康状况的重要信息,血糖含量是评价糖尿病的重要指标。传统方法需要患者从静脉取血,不仅费时、费钱,取血的麻烦和疼痛更使得大多数糖尿病患者不可能按理论上的要求每天多次监测血糖水平。应用近红外光谱法可以实现对人体血糖水平的元损检测,从而大大提高血糖检测的频度,降低糖尿病人长期并发症的危险性,并且摒弃一次性血糖试纸,使自测血糖的费用降低。  相似文献   
974.
三个东方百合品种在滇中鳞茎繁育中的光合特性   总被引:3,自引:0,他引:3  
对西伯利亚、索尔邦、蒂伯3个东方百合品种(Lilium“Oriental Hybrids”)鳞茎繁育过程中植株的气体交换、叶氮含量、叶绿素含量等进行了测定,试图了解东方百合在滇中低纬高原地区的生理生态适应性。3个品种中,蒂伯的光合能力最强,西伯利亚最弱,其光合速率与羧化效率、比叶重及叶氮含量相关,说明其光合能力主要受Rubisco的活性和/或数量影响。3个品种的光补偿点和光饱和点较低,且在高光下没有明显的光抑制现象,对光强表现出宽广的适应性。不同品种的光合最适温度不同,西伯利亚较高(25.5~34.9℃),适宜种植于较温暖的地区;索尔邦较低(19.3~25.6℃),适宜种植于冷凉地区;蒂伯对温度较不敏感,在滇中低纬高原的气候条件下有更广的种植区域。  相似文献   
975.
通过检测东湖的细菌总数、大肠杆菌与纤维素分解菌数目 ,发现东湖的细菌总数与大肠杆菌数目仍严重超标 ,前者为《生活饮用水卫生标准》GB5 74 9- 85的 2~ 99倍 ,后者为此标准的 1 0 0~ 1 0 0 0倍 ,但与一期截污工程完成初期相比已有很大改善 ,说明对东湖的污染治理取得初步成效。各湖区的细菌数目高度异质性 ,其规律与各湖区的有机碎屑数量呈正相关性  相似文献   
976.
通过绘制我国有尾两栖类的地理分布图,分析该类群的地理分布格局与可能的起源和扩散路线。研究结果表明,有尾两栖类在我国的地理分布格局,有三个关键区域:1.位于长江上游的、有尾两栖类物种丰富度最高的横断山区,是有尾两栖类的分布中心,该区域很可能亦为有尾两栖类的起源中心及主要特化中心;2.三个次级分布与特化中心,大别山-淮河流域区、南岭-珠江流域区、浙闽山地-江南水乡区;3.四个小型的三级分布与特化中心,台琼海岛区、东北长白山-三江流域区、秦巴山地-汉江渭河流域区、天山-伊犁河流域区。另外,该类群可能的迁移和扩散路线可归纳为:沿着各水系,从分布中心分别向东西南北四个方向迁移和扩散,其中以向北和向东为主,向南和向西扩散的种类较少。向北扩散的主要是小鲵科(Hynobiidae)的一些种类,向东扩散的种类则以蝾螈科(Salamandridae)物种为主。广布于我国东部的隐鳃鲵科(Cryptobranchidae)种类,极可能是该类群向北和向东这两个方向扩散的结果。研究结果表明,东亚两栖动物区系具有明显的整体性,即东亚两栖动物区系是单源的、本地起源的。本项研究结果支持中国日本界假说。  相似文献   
977.
By employing complex and highly specialized immunochemical methods, several investigators have achieved purification of human α-fetoprotein (AFP) found in fetal serum and/or sera of patients with hepatoma. The present report describes a simpler method which results in the isolation of homogeneous preparation of AFP from human cord serum. AFP was purified by sequential use of Affi-Gel Blue affinity, DE-52 diethylaminoethyl cellulose ion-exchange, immunoadsorption with anti-albumin covalently coupled to Sepharose 4B, and Sephacryl S-200 molecular sieve chromatographic techniques. The homogeneity of the purified AFP was established by subjecting it to polyacrylamide gel electrophoresis, analytical isoelectric focusing, molecular sieve chromatography and immunological techniques. The purified AFP has a molecular weight of approximately 68,000 as determined by polyacrylamide gel electrophoresis in presence of sodium dodecyl sulfate and molecular sieve chromatography, and upon isoelectric focusing yielded a single band pI = 4.8. In addition, the purified AFP gives a single precipitin line when tested against rabbit antiserum to whole human hepatoma serum proteins, and no line(s) of precipitin when tested against rabbit antiserum to normal serum proteins.  相似文献   
978.
基于ITS序列的东亚当归属植物的分类学研究   总被引:4,自引:1,他引:4  
采用PCR直接测序法,测定了东亚地区狭义当归属Angelica s.s.及其近缘共7属40种代表植物的核糖体DNA ITS序列,并结合GenBank中相关植物的ITS序列(含外类群3种),应用遗传距离与系统树分析法对东亚地区狭义当归属植物内部以及当归属与其近缘属植物之间的亲缘关系进行了分析。结果表明:(1)广义当归属中的狭义当归属、柳叶芹属Czernaevia和高山芹属Coelopleurum之间的亲缘关系较近,山芹属Ostericum与它们的亲缘关系较远,这与果实形态、化学分析的结果一致,建议将山芹属作为一个相对独立的分类群处理。(2)ITS序列分析结果支持狭义当归属不是单起源的自然分类群,而应该被分成若干组的观点。(3)ITS序列以及化学成分分析结果表明,前胡属Peucedanum与狭义当归属之间的亲缘关系很近。(4)形态、化学成分以及ITS等多方面分析结果显示,当归A.sinensis与狭义当归属的多数植物之间均有一定的差距,其归属问题值得商榷。(5)ITS序列与化学成分的分析结果均显示藁本属Ligusticum不是一个自然类群。  相似文献   
979.
The aquatic macrophytic vegetation constituting the wetlands situated along the coast of Lake Victoria provides valuable services to both local and regional communities as well as an important ecological function through the transition between terrestrial and aquatic ecosystems. The wetland vegetation is typically rooted in the substrate on the landward side of the lake, but forms a floating mat towards the middle of the wetland and at the wetland/lake interface. Cyperus papyrus and Miscanthidium violaceum vegetation typically dominate the permanently inundated wetland areas along most of the shores of Lake Victoria. Due to the prevailing climatic and hydrological catchment conditions, these macrophytic plants (papyrus in particular) tend to exhibit high net productivity and nutrient uptake which strongly influences both wetland status and lake water quality. In addition, these wetlands provide important economic livelihoods for the local populations. The integrity and physical structure of these wetlands strongly influences their associated mass transport mechanisms (water, nutrients and carbon) and ecosystem processes. Wetland degradation in Africa is an increasing problem, as these ecosystems are relied upon to attenuate industrial, urban and agricultural pollution and supply numerous services and resources. In an integrated project focused on the wetlands of Lake Victoria, the ecological and economic aspects of littoral wetlands were examined and new instruments developed for their sustainable management.  相似文献   
980.
恢复东湖水生生态系统途径初探   总被引:3,自引:0,他引:3  
借鉴国内外其他湖泊的治理经验 ,讨论了如何恢复东湖水生生态系统的一些途径 ,其中探讨了①物理方法 :截污 ,清淤与引水冲污 ;②化学方法 :化学除磷与抑藻或杀藻 ;③生物方法 :用生物量输出氮磷与用生物方法对小型浮游藻类进行控制。  相似文献   
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