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91.
大气氮沉降的不断加剧,改变了土壤理化性质,直接影响植物的生长与发育,间接影响了陆地生态系统碳库,进而可能改变全球气候变化进程。森林是陆地生态系统的主体,因此,弄清氮沉降如何影响森林生态系统碳库,对预测全球气候变化具有重要意义。笔者旨在详细分析氮沉降对森林生态系统土壤碳库输入和输出的影响,阐述氮沉降对森林生态系统凋落物分解、细根周转和土壤呼吸的影响研究进展和作用机制。截至目前,关于氮沉降对于陆地生态系统的影响研究报道较多,且国内外诸多学者也在森林生态系统土壤碳库对氮沉降的响应领域开展了较多试验研究,但多集中于碳输入和输出的总量分析,而对输入和输出各个组分的研究相对较少。笔者综述了国内外有关森林生态系统碳库输入和输出各组分对氮沉降响应的相关研究,为进一步揭示其响应机制和途径提供参考依据。 相似文献
92.
减少发展中国家毁林及森林退化引起的温室气体排放, 森林保护、可持续森林管理和增加森林碳储量(REDD+)在减缓气候变化行动中的作用越来越明显, 已经成为《联合国气候变化框架公约》谈判的重要议题。近年来各缔约方针对方法学、融资机制和REDD+与清洁发展机制(CDM)关系的谈判争论越来越激烈。在《联合国气候变化框架公约》第18次缔约方会议(COP18)期间, 对REDD+议题提出了新的要求, 除了有关于逐步建立国家水平森林参考排放水平或参考水平等有关方法学的技术与科学问题外, 基金在融资机制中的作用和非碳效益支付议题也有待进行深入的磋商。文中基于对各缔约方提案的分析结果和REDD+示范项目开展情况, 结合我国森林资源现状, 分析了REDD+机制对我国可能产生的影响并提出后续谈判期的对策建议。 相似文献
93.
94.
为了明确ABA对孕穗期低温下水稻结实率及叶片生理特性的调控效应,本试验在盆栽条件下,以2个水稻(Oryza sativa L.)品种‘龙粳11’(冷敏型)和‘龙稻5’(耐冷型)为材料,于孕穗期在人工气候室进行低温(15℃,持续1,2,3,4,5天)处理,并喷施不同浓度的脱落酸(ABA),研究低温条件下ABA对不同水稻结实率的调控效应,同时探讨了ABA和低温对水稻叶片膜透性、抗氧化酶等生理特性的影响。结果表明:低温条件下,‘龙稻5’的结实率变化不大,‘龙粳11’的结实率显著降低,20 mg/L的ABA能够有效缓解低温伤害,相对提高低温胁迫下水稻的结实率。叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性表现出先升高后下降的变化趋势,‘龙稻5’的抗氧化酶活性、可溶性糖和可溶性蛋白含量高于‘龙粳11’,但丙二醛(MDA)含量和相对电导率低于‘龙粳11’。ABA可提高冷敏品种的抗氧化酶活性、可溶性糖和可溶性蛋白的含量,同时可降低MDA含量和相对电导率。这说明ABA可以通过调控水稻抗氧化酶、可溶性糖等生理指标的活性及含量,进而提高冷敏水稻品种的耐冷性。 相似文献
95.
利用超声波提取和气质联用分析法,对散尾葵的提取物进行了组分和含量分析。结果表明,提取物含酸类化合物2种,占提取物总量的1.20%;醇类化合物3种,占提取物总含量 1.78%;酯类化合物5种,占提取物总量的7.11%;烷类化合物5种,占提取物总量的13.27%;醚类化合物2种,占提取物总含量 3.36%;酮类化合物1种,占提取物总含量 0.41% 。利用散尾葵提取物对10种居室空气中收集的细菌进行了抑菌性测定,对其中7种具有抑菌活性,而对放线菌、动性球菌、冷杆菌无抑制作用。对葡萄球菌和枯草芽孢杆菌抑菌力最强,125mg/mL浓度提取液抑菌率达到100%。 相似文献
96.
本试验从健康的鸡盲肠内容物中筛选出具有较高抑菌活性的病源拮抗菌JM-11菌株,经形态、生理生化及16S rDNA序列鉴定此菌为枯草芽孢杆菌(Bacillus subtilis subsp. subtilis)。经耐受胃肠道环境及胆盐试验,结果表明,JM-11菌株能耐受0.3%的胆盐环境,在pH为3.0的人工胃液中能够很好的存活。利用抗生素打乱雏鸡肠道菌群后,饲喂致病性大肠杆菌来制作腹泻模型。经益生菌JM-11对腹泻雏鸡的治疗试验结果显示,JM-11能显著降低腹泻雏鸡粪便中的大肠杆菌的数量(P<0.01),增加乳酸菌的数量(P<0.01),提高雏鸡免疫器官指数(P<0.05),对雏鸡具有安全无毒的作用。 相似文献
97.
Awareness of animal influenza and its prevention and control is important for ensuring livestock health, production and welfare. In China, a country stereotyped as a major source of emerging zoonotic infectious diseases, research on the public understanding of animal influenza is limited to the Han, the main ethnic group. The present qualitative study in Southwest China investigated awareness of animal influenza among the Dai, an ethnic minority. The participants (15 men and 10 women, ages 18–83) were smallholder farmers of pigs and poultry in rural areas of Jinghong, Xishuangbanna, Yunnan Province. A mixture of interviews and group discussions took place in homes and villages. The participants were asked about their knowledge of avian influenza (H7N9), swine influenza (H1N1), precautions taken to protect against influenza, procedures when animals were sick and perceived risk of animal influenza. The data were analysed following coding and thematic analysis. The findings demonstrated a limited understanding of animal health and welfare among participants. Specifically, they were largely unaware of animal influenza (H7N9, H1N1) including its causes, symptoms, prevention and treatment. The farmers were also uninformed of the risks they faced and unknowingly engaged in behaviours which increased direct or indirect exposure to infected animals, a risk factor for human infection. They also reported poor usage of veterinary services. In order to guarantee the health, welfare and production of their livestock, immediate action is needed to enable Dai smallholder farmers to prevent and respond to animal influenza effectively and timely. 相似文献
98.
栽桑养蚕是巫溪县农村的传统产业,是蚕区农民致富奔小康的骨干项目。自上世纪80年代初,县委、县府就已将栽桑养蚕作为农村特色产业大力发展,1988年首次突破万担茧大关,发种量达到2万张,蚕农收入逾500万元;丝厂绸厂从无到有逐渐完善,农、工、贸产业链已基本形成。全县12个乡镇、88个养蚕村、2万余农户,8万多人口从事栽桑养蚕;在地桑0.8亿株、年养蚕4万余张、产茧1 000t、收入1 600万元以上。2006年《重庆市百万担优质蚕茧产业化工程“十一五”发展规划》把巫溪等渝东南10个区市县列为重庆市生产优质蚕茧最适宜区域重点发展,规划我县在“十一五”期内达到2 500t优质蚕茧的规模。要达到这一目标,摆在我们面前的任务是如何深挖潜力,努力提高蚕茧单产,特别是努力提高夏秋蚕单张产量,为整体提高全县养蚕的科技水平,作出自己新的贡献。1基本概况1.1自然概况我县位于渝陕鄂交汇处,东经108°44′~109°58′,北纬31°14′~31°44′之间,最低海拔135m,最高海拔2 797m(阴条岭山为重庆第一峰),由于海拔差异大,形成了独特的立体气候,素有“一山兼四季、十里不同天”的美称。终年气候温和,雨量充沛,日照时间长... 相似文献
99.
Yueh SC Wang YH Lin KY Tseng CF Chu HP Chen KJ Wang SS Lai IH Mao SJ 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2008,70(4):379-387
Porcine haptoglobin (Hp) is an acute phase protein. Its plasma level increases significantly during inflammation and infection. One of the main functions of Hp is to bind free hemoglobin (Hb) and inhibit its oxidative activity. In the present report, we studied the Hp phenotype of Taiwanese Lanyu miniature pigs (TLY minipigs; n=43) and found their Hp structure to be a homodimer (beta-alpha-alpha-beta) similar to human Hp 1-1. Interestingly, Western blot and high performance liquid chromatographic (HPLC) analysis showed that 25% of the TLY minipigs possessed low or no plasma Hp level (<0.05 mg/ml). The Hp cDNA of these TLY minipigs was then cloned, and the translated amino acid sequence was analyzed. No sequences were found to be deficient; they showed a 99.7% identity with domestic pigs (NP_999165). The mean overall Hp level of the TLY minipigs (0.21 +/- 0.25 mg/ml; n=43) determined by enzyme-linked immunosorbent assay (ELISA) was markedly lower than that of domestic pigs (0.78 +/- 0.45 mg/ml; p<0.001), while 25% of the TLY minipigs had an Hp level that was extremely low (<0.05 mg/ml). In addition, the initial recovery rate (first 40 min) in the circulation of infused fluorescein isothiocyanate (FITC)-Hb was significantly higher in the TLY minipigs with extremely low Hp levels than those with high levels. This data suggests that the low concentration of Hp-Hb complex is responsible for the higher recovery rate of Hb in the circulation. TLY minipigs have been used as an experimental model for cardiovascular diseases; whether they can be used as a model for inflammatory diseases, with Hp as a marker, remains a topic of interest. However, since the Hp level varies significantly among individual TLY minipigs, it is necessary to prescreen the Hp levels of the animals to minimize variation in the experimental baseline. The present study may provide a reference value for future use of the TLY minipig as an animal model for inflammation-associated diseases. 相似文献
100.
Shiilegdamba E Carpenter TE Perez AM Thurmond MC 《Veterinary research communications》2008,32(3):201-207
Prior to 2000, foot-and-mouth disease (FMD) had not been observed in Mongolia since 1973; however, between April 2000 and
July 2002, Mongolia reported 44 FMD outbreaks that affected cattle, sheep, goats, and camels. The objectives of this study
were to describe the distributions of the 44 reported FMD outbreaks in Mongolia and to assess their spatial clustering and
directions of movement. Official reports were collected to obtain the number and species of animals both affected and at risk,
and the date and geographical coordinates of each outbreak. Significant global and local spatial clusters of reported FMD
outbreaks were identified. Disease spread during the second epidemic moved 76° northeast and the spread of the disease during
the third epidemic moved 110° northwest. FMD outbreaks were clustered intensely close to other FMD-positive counties. These
findings can be used in the future to help plan prevention and control measures in high risk areas. 相似文献