334 research outputs found

    Biomass and growth analysis of Paspalum wettsteinii community in South Fujian, China

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    禾本科多年生牧草宽叶雀稗适宜在福建南亚热带丘陵酸性赤红壤上生长,人工种植的宽叶雀稗群落鲜草产量峰值在8月份,为4050g·m-2,生物量峰值(干重)则出现在9月份,其中地上部1398.8 g·m-2、地下部770.8g·m-2。群落全年生长呈周期性变化,生物量波动符合Logistic曲线:y=1634.46/(1+e2.67976-1.3.369×10-2t)。根据9月份最高现存量估计,其年净第一性生产力为2169.6g·m-2·a-1。群落生长分4个阶段:缓慢增长(2~4月)、加速增长(5~6月)、减速增长(7~9月)、生长停滞和下降(10~12月)。降雨量是影响生物量的重要因素,二者呈显著线性正相关,相关系数为0.9783,回归方程为y=-74.3779+0.9480x。Paspalum wettsteinii Hackel, a kind of perennial herbages of Graminaea, was proved to get good adaptation to hilly crimson soil in the southern part of subtropical zone in Fujian Province. Its growth curve fluctuated periodically within a year. The biomass value of above-ground part of the community reached to its highest point, 1398. 8 g m-2 in August, 1994; the under-ground part 770. 8 g m-2 in September. Biomass of the community fluctuated in accordance with the logistic curve: y=1634. 46/ (1+e2.67976-1.30369x10-2t) . The highest value of the community's fresh weights measured monthly was 4050 g m-2 (Aug. 1994) . Estimated by Peak Standing Crop in Sept. 1994, the annual NPP of the community was 2169. 6 g m-2 a-1. Through a growth analysis, the above ground part biomass of the community changes with four stages: slow increasing (Feb. -Apr. ); acceleration increasing (May-June); deceleration increasing (July-Sept. ); stagnation and descent (Oct. - Dec. ). Of all the factors that affect the biomass value, the rainfall was an important one. Their regression equation was y= - 74. 3779+0. 9480x, and the relation coefficient (r) was 0. 9783

    Pneumocystis carinii pneumonia in renal transplant recipients treated with cyclosporin

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    Four cases of pneumocystis carinii pneumonia occurred among 38 renal transplant recipients. Diagnosis was confirmed by cyst concentration technique in 2 cases. The other 2 cases were clinically, from the rapid improvement of fever, pulmonary infiltrates and hypoxia following a therapeutic trial of high dose sulfamethoxazole-trimethoprim. All patients responded to treatment with high dose sulfamethoxazole-trimethoprim. Three patients survived pneumocystis carinii pneumonia, but i died due to aspergillosis. One patients showed serological evidence of concomitant cytomegalovirus infection

    Effects of Soil Salinity on the Quality of Carrot

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    采用土壤盆栽试验,设置6个盐度水平(0、500、1000、1500、2000、2500 Mg/kg),研究胡萝卜种植过程中盐度对其叶绿素、维生素C、可溶性糖、可溶性蛋白质及硝酸盐含量的影响。结果表明,种植胡萝卜的土壤盐度控制在500 Mg/kg,可以提高胡萝卜的品质,减少盐分对土壤的损伤。具体表现为,500 Mg/kg盐度处理对胡萝卜叶绿素含量无显著影响,而高盐度使胡萝卜叶绿素总含量降低;500~1000 Mg/kg盐度可增加胡萝卜维生素C和可溶性蛋白质含量;可溶性总糖含量以500 Mg/kg处理的降低幅度最小,500~2000 Mg/kg处理使胡萝卜硝酸盐含量呈降低趋势,但高盐度(2500 Mg/kg)则会增加其硝酸盐含量。A soil pot experiment with different levels of saltnity(0,500,1500,2000,2500 mg/kg) were carried out to study the effects of salinity on the quality of carrot.The results showed that controlling certain salinity 500 mg/kg,could improve the quality of carrot.Because the salinity of 500 mg/kg had no effect on the chlorophyll content of carrot,and high salinity caused total chlorophyll content decreased,low salinity was conducive to the promotion of carrot synthesis of vitamin C and soluble protein,soluble sugar content of carrot was decreased by the increasing of salinity levels,Nitrate content in carrots increased at the high salinity(2500 mg/kg) treatment.厦门市科学技术局项目(3502Z20071098

    Controlled release method for herbicides in rhizosphere to prevent aggression of Spartina alterniflora in intertidal zone

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    为防除滨海滩涂互花米草入侵,探讨根际土壤缓释除草剂的新方法。该研究采用扩散法研究了蛭石、PE膜和合成壳聚糖膜3种缓释材料的根际缓释除草剂的性能,同时,采用根部浸泡试验验证根际施药防除互花米草的效果。结果表明,3种缓释材料的缓释性能差异显著,蛭石对草甘膦控释能力较弱,初始释放农药量最大,释放迅速,适合淤泥质潮滩;PE膜则表现出较强的控释能力,释放量较小,但整个过程释放量较稳定,适合沙质和近根际水体;壳聚糖膜介于两者之间。根部浸泡试验表明,0.25~1.00g/l草甘膦、0.09~0.23g/l百草枯、0.28~2.30g/l草铵膦根部浸泡2~6d即可显现毒杀互花米草效果,通过饱和土壤一维溶质渗滤模型计算,在点源释放模式下,除草际根部释放点间有效除草间距为50~60CM。研究证明了根际缓释除草剂防除互花米草具有可行性。To guard effectively against the ecological aggression of the smooth cord-grass Spartina alterniflora growing in intertidal zone,a new method was considered to apply herbicides in rhizosphere soil with controlled release techniques.Three types of controlled release materials,vermiculite particles,polyethylene(PE) and chitin membrane,were tested on their herbicide-releasing characteristics,meanwhile,three herbicides,including glyphosate,parauat and basta,were evaluated on the effects of killing the smooth cord-grass.The results show that the controlled herbicide-releasing ability of vermiculite particles is weaker than the other two materials,and its initial releasing quantity is bigger,so it can be used for the muddy beach.On the contrary,that of PE was stronger,and therefore it is suitable for a sandy beach.Furthermore,that of chitin membrane is between the vermiculite particles and PE membrane.The three herbicides,glyphosate,paraquat and basta,can kill the grass effectively after 2-6 days of cultivation in 0.25-1.00 0.09-0.23 and 0.28-2.30 g/L solutions,respectively.One dimensional model for solute infiltration in saturated soil was used to modulate the herbicide migration,and the modulation result suggested that the distant between any two herbicide-releasing points should be set at less than 50-60 cm in field weeding practice.The experiment proved it is feasible in practice to guard against the ecological aggression of smooth cord-grass by controlled release of herbicides in rhizosphere.国家海洋公益性行业科研专项经费项目(200905009)资

    深圳福田白骨壤红树林生物量和能量研究

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    本文探讨了深圳福田红树林保护区56年生白骨壤群落的生物量、生长量及能量分布。结果表明:该群落现存生物量为1658388g/m2,其中地上部占6678%,地下部占3322%。年增长量(1993)为11498g/m2。植物体各组分热值含量变化范围在161~1822KJ/g,其中以树干材热值含量居最高,而中根最低;群落能量现存量为291839KJ/m2,其中地上部占6851%,地下部占3149%;群落年增长能量存留量(1993)为20213KJ/m2

    Current status of mangrove germplasm resources and key techniques for mangrove seedling propagation in China

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    红树植物种质与种苗生产是所有红树林生态恢复工程的基础.本文根据工程实践并结合已有研究资料,采用聚类分析等方法,对中国红树植物资源现状与苗木繁育关键技术进行初步分析.结果表明:中国红树群落可分为低温广布型、广布型、嗜热广布型和热带分布型4种类型;资源分布可划分为琼东沿海、北部湾沿海、珠江口至粤东沿海、闽南和台湾沿海、闽东至浙南沿海5个区域.其中,北部湾沿海红树林种质资源占全国的75.3%.目前中国红树植物苗木种类开发利用率为52.6%,以胎生红树植物为主.红树林苗木生产应注意繁育方法、种实采集与储存、育苗方式、水分和盐度选择、病虫害防治及越冬防寒措施6个技术环节.结合调查和生产实践,归纳分析了中国现有5种红树林苗圃类型(旱地设施苗圃、红树林滩涂苗圃、光滩苗圃、基围塘苗圃和米草滩涂苗圃)的结构和用途特点,为红树林生态恢复工程的系统集成管理提供参考.Mangrove germplasm and nursery operation are the foundations of all mangrove ecological restoration projects.Based on the existing literatures and our own experiences,and by using cluster analysis and other methods,this paper assessed the current status of the mangrove germplasm resources and the key techniques for mangrove seedlings propagation in China.In China,the mangrove communities could be divided into 4 types,including low temperature tolerant widespread type,widespread type,thermophilic widespread type,and tropical type,and the mangrove distribution sites could be divided into 5 regions,i.e.,eastern Hainan coast,Beibuwan Gulf coast,Pearl River estuary and eastern Guangdong coast,southern Fujian and Taiwan coast,and eastern Fujian and southern Zhejiang coast.The mangroves in Beibuwan Gulf coast region took up 75.3% of the total mangrove germplasm resources in the country.At present,the percentage of the mangrove species applied for seedling propagation in China was estimated at 52.6%,most of which were of viviparous species.The six key steps in mangrove nursery operation included the selection of proper seedling propagation methods,the collection and storage of seeds or propagules,the ways of raising seedlings,the management of water and salinity,the control of diseases and pests,and the prevention of cold damage during winter.The structure,functions,and applications of the present five types of mangrove nurseries,including dry land nursery,mangrove tidal nursery,mudflat nursery,Jiwei pond nursery,and Spartina mudflat nursery,were also analyzed,which could provide guidance for the integrated management of mangrove ecological restoration engineering.林业科技支撑计划项目(2009BAD2B0605);国家海洋公益性行业科研专项经费项目(200905009)资

    Promotional Effects of Ni and Mg on the Preferential Oxidation of CO over Carbon Nanotube-Supported Pt Catalyst

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    采用共浸渍法制备了nI和Mg促进的碳纳米管载PT催化剂(PT-nI-Mg/CnT),考察了其对CO优先氧化的催化性能.结果表明,PT,nI和Mg在CnT表面发生了相互作用,可能存在合金纳米粒子,从而显著改善了催化剂CO优先氧化的催化性能.添加适量nI可提高CO的转化率,而加入适量Mg则有助于改善CO2的选择性.当PT,nI和Mg同时负载时,优化后所得的催化剂5%PT-5%nI-5%Mg/CnT在100°C对富H2气体中CO选择氧化的转化率为100%,CO2的选择性为53.7%;该催化剂在140°C下连续反应24H,催化活性稳定.A carbon nanotube-supported Pt catalyst promoted by Ni and Mg(Pt-Ni-Mg/CNT) was prepared by the co-impregnation method for preferential oxidation of CO in H2-rich gas.The results of X-ray diffraction, H2 temperature-programmed reduction, transmission electron microscopy, and energy dispersive spectroscopy indicated that Pt interacted with Ni and Mg on CNT surface and might form alloy nanoparticles to some extents, which in turn markedly improved the catalytic performance of preferential oxidation of CO in H2-rich gas.The results of performance tests showed that CO conversion at low temperatures could be effectively enhanced by adding a proper amount of Ni, while the selectivity was improved by adding a proper amount of Mg.When Ni and Mg were added simultaneously, the 5%Pt-5%Ni-5%Mg/CNT catalyst showed CO conversion of 100% and selectivity for CO2 of 53.7% in a H2-rich stream at 100 °C.The catalytic performance did not change obviously during 24 h of run at 140 °C.国家重点基础研究发展计划(973计划;2009CB939804);福建省科技重大专项前期项目(2009HZ10102
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