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991.
While there are numerous wildlife ecology studies in lowland areas of Nepal, there are no in‐depth studies of the hilly Churia habitat even though it comprises 7642 km2 of potential wildlife habitat across the Terai Arc. We investigated tiger, leopard and prey densities across this understudied habitat. Our camera trapping survey covered 536 km2 of Churia and surrounding areas within Chitwan National Park (CNP). We used 161 trapping locations and accumulated 2097 trap‐nights in a 60‐day survey period during the winter season of 2010–2011. In addition, we walked 136 km over 81 different line transects using distance sampling to estimate prey density. We photographed 31 individual tigers, 28 individual leopards and 25 other mammalian species. Spatial capture–recapture methods resulted in lower density estimates for tigers, ranging from 2.3 to 2.9 tigers per 100 km2, than for leopards, which ranged from 3.3 to 5.1 leopards per 100 km2. In addition, leopard densities were higher in the core of the Churia compared to surrounding areas. We estimated 62.7 prey animals per 100 km2 with forest ungulate prey (sambar, chital, barking deer and wild pig), accounting for 47% of the total. Based on prey availability, Churia habitat within CNP could potentially support 5.86 tigers per 100 km2 but our density estimates were lower, perhaps indicating that the tiger population is below carrying capacity. Our results demonstrate that Churia habitat should not be ignored in conservation initiatives, but rather management efforts should focus on reducing human disturbance to support higher predator numbers.  相似文献   
992.
An 8‐week feeding trial was conducted to evaluate the effects of ascorbic acid (AsA), in the form of l ‐ascorbyl‐2‐polyphosphate (LAPP) on growth performance, body composition, antioxidative capacity and salinity stress tolerance of juvenile Pacific white shrimp, Litopenaeus vannamei. Five practical diets (46% crude protein and 7.6% lipid) supplemented with graded levels of AsA (14.64, 48.55, 84.98, 308.36 and 639.27 mg kg?1 diet) were fed to five replicate groups of L. vannamei (mean initial wet weight 0.57 g). No significant differences were found on growth performance among all treatments. However, whole body lipid content significantly decreased with dietary AsA levels increasing. Activities of total antioxidant capacity, glutathione reductase and glutathione peroxidase were significantly affected by dietary AsA levels. Shrimp fed LAPP‐free diet had higher malondialdehyde content than those fed the diets supplemented with LAPP. Dietary AsA levels higher than 308.36 mg kg?1 diet increased the survival of shrimps after 1, 2 and 3 h of acute salinity change. Broken‐line regression analysis on survival after 3 h of salinity stress and second‐degree polynomial regression analysis on glutathione reductase data indicated that the optimal dietary AsA requirement of L. vannamei was estimated to be 306.39, 319.75 mg kg?1 diet respectively.  相似文献   
993.
长牡蛎和福建牡蛎分别是我国北方和南方沿海重要的养殖贝类。为比较分析二者的动态生长情况,实验基于动态能量收支理论(DEB),以连续监测的水温和叶绿素a浓度为强制因子,通过现场实验、模型调试和文献查阅等方式获取模型参数,利用Python 2.7软件分别构建了桑沟湾长牡蛎、深沪湾福建牡蛎的个体生长模型,并以两种牡蛎的实测生长数据进行验证。结果显示:①所构建的DEB模型能够较好地模拟长牡蛎、福建牡蛎的个体生长情况(壳高、软组织湿重等),模拟值与实测值之间相关性显著;②长牡蛎和福建牡蛎的温度耐受上限(TH)、温度耐受下限(TL)、半饱和常数(FH)等参数存在差异,这可能与不同海域的理化环境、食物组成及牡蛎的选择性摄食有关;③在模拟周期内,受温度和食物的双重限制,长牡蛎冬季生长缓慢,而福建牡蛎处于持续增长状态,期间主要受到食物的限制。本研究结果可为后续生态系统模型构建和牡蛎养殖容量评估提供基础数据。  相似文献   
994.
Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012–2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).  相似文献   
995.
The analysis of China wind power industry   总被引:6,自引:0,他引:6  
The development course of China wind power industry is reviewed by six stages. National policies on wind power industry are elaborated from the aspects of laws & regulations, planning, finance & taxation and electrovalence policy. And these policies have played an important supporting and regulating role in the development of wind power industry. The development status of China wind power industry is analyzed based on wind turbine installed capacity, wind power output and their growth rate. It is explained that national wind turbine manufacturers have kept developing and become strong by the data of new global installed capacity share of mainland wind turbine manufacturers in 2013 and the new global market share of 8 domestic enterprises among the world top 15 wind turbine manufacturers. But there are still 5 key problems which influence the development of national wind turbine need to be solved, including lack of top-level design, abandon and restriction wind power seriously, lack of R&D abilities, some of the key parts relying on imports and wind turbine facing a quality guarantee dilemma. Taking Sinovel Wind Group Co. Ltd. and Xinjiang Goldwind Sci & Tech Co. Ltd., the two leading companies as an example, their performance is analyzed and it’s pointed out that the wind industry must keep vigilant after the overspeed development. The enterprises should try to avoid neglecting cultivating their inner core competitive ability, including technology advancements and products reliability. Occupying the market with low price competition and expanding blindly is also not desirable. At last, the development prospects of our country’s wind power industry are analyzed and three proposals are put forward.  相似文献   
996.
根据CFG桩复合地基的承载机理和特性,提出了CFG桩的应用与设计。并参照《建筑地基处理技术规范》(JGJ79-2002),结合工程实例中单桩承载力及复合地基承载力标准值的计算,对其在复合地基中的适用性和可行性进行了探讨。  相似文献   
997.
游憩环境承载力是诊断游憩环境健康运行的依据和标准。为测度山地草甸游憩环境运行状态,从弹性力、支撑力和抵抗力3个方面遴选20个评价指标,构建了山地草甸游憩环境承载力评价指标体系,然后根据经验数据及试验数据确定了各指标以及各承载力指数的阈限范围,并构建了相应的承载力指数模型。在此基础上运用此评价指标体系及模型方法对武功山山地草甸游憩环境承载力进行评价。结果表明:武功山山地草甸游憩环境尽管具有较强的自我维持和自我调节的弹性能力,甚至淡季时还具有较高的抵抗力,但在旺季高负荷的游憩行为干扰下,其支撑能力和抵抗能力均处于"超载"状态,承载力综合指数为0.426 3,也处于"超载"状态;同时旺季的"超载"还进一步影响到了淡季时草甸的自我恢复能力,其承载力综合指数为0.566 1,处于"满载"状态。  相似文献   
998.
长期施肥对红壤磷素持续供应能力的影响   总被引:6,自引:0,他引:6  
以长期施肥(始于1988年)的旱地红壤为研究材料,通过对历史数据的统计与分析,讨论了红壤全磷累积量与有效供磷量之间的相互关系,同时,通过有效磷的连续提取实验研究了红壤的持续供磷能力。研究结果表明:在长期施肥的过程中约有76.9%~86.8%的磷素积累在旱地红壤中,有效磷水平是红壤磷素肥力高低的直观表现,随着土壤全磷累积量的增大而增加;土壤磷素的纯盈余量又决定着全磷与有效磷的供应水平。由连续提取实验结果可以初步推测,如果现在减少或停止施用磷肥,红壤现有的供磷水平至少可以满足3~4季作物的磷素需求。因此,应在兼顾土壤磷素的农业效应和环境安全的前提下,建立新的施肥制度,使磷素资源的利用更加合理化。  相似文献   
999.
以上海市某火力发电厂周边地区土壤及木本植物为研究对象,利用湿法消解和电感耦合等离子体发射光谱仪(ICP-AES)测定了其中Cd、Cr、Pb、Cu、Zn、As等6种重金属的含量。通过单因子污染指数法、内梅罗污染指数法和潜在生态危害指数法分析了该地区土壤重金属污染状况和潜在生态危害。同时研究了当地木本植物积累和转运重金属的能力。结果表明,土壤中Cd达到了中度或重度污染水平,其潜在生态危害指数也达到了严重级别;而其余5种重金属均处于清洁水平。但是该区的内梅罗综合污染指数均达到了轻度污染或中度污染的水平。对植物重金属含量的分析表明,样地中15种优势树种对重金属的吸收能力普遍较弱。综合分析植物对6种重金属的积累能力,黄杨(Buxus sinica)、金钟花(Forsythia viridissima)、红花檵木(Loropetalum chinense)和苦楝(Melia azedarach)积累重金属的能力较强;而水杉(Metasequoia glyptostroboides)、黄山栾树(Koelreuteria bipinnata)、构树(Broussonetia papyrifera)转移重金属的能力较高。并且这几种植物在样地中的生长状况良好,适于作为此类重金属污染厂区的生态防护绿化树种。  相似文献   
1000.
干露对三疣梭子蟹抗氧化和应激能力的影响   总被引:2,自引:1,他引:2  
姜娜  王芳  路允良  董双林 《水产学报》2014,38(12):1996-2004
在实验室条件下,研究了干露时间(0.5、1.5和3 h)胁迫对三疣梭子蟹抗氧化能力和应激能力的影响,初步探讨了能够较灵敏地指示梭子蟹健康状况的胁迫指标。结果显示:(1)干露时间胁迫对超氧化物歧化酶(SOD)活力和丙二醛(MDA)含量均无显著影响(P0.05);但干露时间显著影响肝胰脏总抗氧化能力(T-AOC)水平、热休克蛋白70(HSP70)表达量和肌肉乳酸含量(P0.05)。(2)0.5 h干露胁迫后,SOD活力在入水恢复4 h时达到峰值;MDA含量在入水恢复2~10 h内显著高于对照组水平(P0.05);T-AOC水平在恢复阶段基本维持在对照组水平。1.5和3 h干露后,SOD活力在入水恢复阶段一直维持在对照组水平,且各时间点与对照组差异不显著(P0.05)。1.5 h干露后MDA含量在入水恢复阶段呈先升高后降低趋势,各时间点与对照组差异不显著(P0.05);而3 h干露后入水恢复10 h时显著增加(P0.05)。1.5 h干露后入水恢复4 h时,T-AOC水平显著高于对照组(P0.05);3 h干露后入水恢复0.5 h时显著升高(P0.05),2~10 h内基本恢复到对照组水平。干露时间胁迫后,乳酸含量均在入水恢复0.5 h时达到最大值;HSP70表达量均在入水恢复2~4 h内达到峰值。研究表明,相比于其他所选指标,T-AOC水平能够较敏感地反映干露时间胁迫对机体的生理状态的影响;SOD和MDA相互配合能够较灵敏地反映不同干露时长后机体在恢复阶段的免疫水平。  相似文献   
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