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11.
This study aimed at identifying the factors that affected the survival of faecal coliforms as measured by E. coli in four types of soils in Botswana which were amended with sewage sludge. Physico-chemical and biochemical properties and coliform population in the different soils, sludge, and soil/sludge mixtures were determined after sampling, on composing the soil/sludge mixtures, and 90 days after composing. Coliform population in the different soil/sludge mixtures decreased by about 90% after 90 days. The age of the sludge used and the rate at which it was applied to the soils initially determined the population of E. coli in each soil/sludge mixture, but after 90 days, differences inherent in the different soil types were the main determinants of the E. coli population. Percentage reduction of coliforms in Type 1 sludge mixtures were lower (38%) than in Type 2 sludge mixtures (57%). Up to 79.8% of the reduction observed in E. coli population in the Barolong luvisol-sludge mixtures after 90 days was caused by reduction in pH and moisture content, while 72.6%, 84.5% and 55.1% of the reduction in E. coli population in Tuli luvisol-, arenosol- and vertisol-sludge mixtures, respectively, was accounted for by the reduction in moisture content and Olsen P concentration. Coliform survival rates varied with soil types being 12%, 6.4%, 5.3% and 5.8% for the vertisol, arenosol, Barolong luvisol and Tuli luvisol, respectively. A minimum period of 90 days should be allowed between when sludge is applied to similar soils and when seeds are sown. The exact period should, however, be determined by the properties of the soil with fine-textured soils requiring a longer period than coarse-textured soils. 相似文献
12.
科尔沁沙地小叶锦鸡儿灌木林固沙效应的研究 总被引：10，自引：1，他引：10
对流动沙丘上栽植的6年和11年生小叶锦鸡儿灌木林防风固沙效应进行了测定与分析,研究结果表明：（1）在小叶锦鸡儿灌木林内各个高度风速和输沙量均显著低于流动沙丘,防风固沙效果明显。（2）小气候得到改善,小叶锦鸡儿林内空气温度低于流动沙丘,相对湿度则高于流动沙丘,土壤浅层温度变幅明显小于流动沙丘,有利于植物生长。（3）随着植被生长发育年限的增加,土壤理化性质均得到不同程度改善。土壤中微沙（0.05-0.1mm）和粘粒（〈0.05 mm）含量增加,表层土壤容重减小,孔隙度增大,土壤持水能力提高;土壤中有机碳、全氮、速效氮及速效钾含量逐年增加,土壤肥力有所提高。 相似文献
13.
沙棘的花芽分化及花器发育进程研究 总被引：2，自引：0，他引：2
LI Xiao-yan WANG Lin-he LI Lian-guo IU yan ZHAO Ling-zhi College of Agronomy InnerMongolia Agricultural Institute Huhhot China Diversity Station of Agricultural Bureau Huhhot China 《华北农学报》2006,(Z3)
利用光学显微镜对中国沙棘花芽分化及花器发育进程进行观察研究,结果表明:沙棘花芽分化分为花芽分化开始期、花序分化期、花蕾分化期、花萼分化期、雄蕊分化期、雌蕊分化期。花粉性细胞的发育经过花粉母细胞、二分体、四分休、单核花粉粒、双核花粉粒几个阶段。胚囊发育包括孢原阶段、四分孢子、经减数分裂,形成成熟胚囊等几个阶段。该研究为合理制定沙棘的栽培技术措施和培育新品种提供了科学依据。 相似文献
14.
本文对洛克沙胂在鲫鱼体内的砷残留及消除动力学进行了研究，鲫鱼在室内水池洛克沙胂溶液10mg／L(以As计)中连续暴露15天进行富集残留试验后转入清水中进行消除试验。采用微波消解处理和氢化物一原子荧光光度法测定鱼鳃、肌肉、血清和内脏中总砷含量。结果表明，砷在鱼体内的表现为吸收和分布较快，肌肉和血清中总砷水平仅为0．3～0．4mg／kg，内脏中残留最高达30．25mg／kg。洛克沙胂在鲫鱼组织中消除符合一级速率动力学过程，消除半衰期(t1／2)为2．5～2．8h，鱼鳃中砷浓度在初始2h内下降快，此后消除较慢，t1／2为9．45h。 相似文献
15.
氮磷钾肥施用量及施用时期对马铃薯养分转运分配的影响 总被引：2，自引：0，他引：2
通过田间小区试验,研究了氮磷钾不同施用量和施用时期对马铃薯块茎产量和N、P、K吸收累积动态及分配转运的影响。结果表明:不同施肥处理块茎产量在33.5～38.6 t/hm2之间,氮肥农学效率在12.3～50.3 kg/kg之间。与高氮磷低钾处理相比,低氮磷高钾处理显著提高了块茎产量、商品薯产量、商品薯率和氮肥农学效率(P<0.05);以低氮磷高钾且氮肥分期施用的处理最佳。不同施肥处理对养分积累趋势影响不大,但可显著影响各器官在不同生育期的养分积累量及分配比例。收获时低氮磷高钾处理不但能增加块茎中氮、磷、钾养分的积累量和分配比例,还利于提高氮、磷、钾养分向块茎的转运率。将部分氮肥在块茎膨大前追施可更有效提高块茎中的养分分配比例,在追施氮肥的基础上再追施钾肥仅略提高了商品薯比例。 相似文献
16.
为研究含氮物质在绒山羊体内的分配规律,本研究选择年龄在2~2.5周岁的绒山羊羯羊,采用消化代谢和氚水稀释技术结合的方法测定不同时期绒山羊总氮沉积量、体氮和毛绒氮的分配量。结果表明,用消化代谢和氚水稀释技术可以准确地测定绒山羊的体氮和毛绒氮的分配量,不同时期的体氮和毛绒氮的分配比例有较大差异。在非生绒期和生绒旺盛期,体氮的分配比例分别为75.7%±0.62%和66.6%±2.2%,毛绒氮的分配比例分别为24.3%±0.62%和33.4%±2.2%,表明不同时期绒山羊的生长方向发生变化。同时发现内分泌也随季节发生变化,主要表现为非生绒期PRL(催乳素)和IGF-I(类胰岛素生长因子I)的水平高,MT(褪黑素)的水平低;生绒旺盛期PRL和IGF-I的水平低,MT的水平高。证明了氚水稀释技术在测定动物氮分配中的可行性,揭示了不同时期含氮物质在绒山羊体内分配的变化规律以及内分泌在这些变化中的调节作用,为不同季节对绒山羊采取合适的饲养管理提供了理论依据。 相似文献
17.
Helene Baudel Helene De Nys Eitel Mpoudi Ngole Martine Peeters Alice Desclaux 《Zoonoses and public health》2019,66(3):288-295
The ecology of Ebola virus (EBV) remains largely unknown, but the previous detection of viral RNA and anti‐EBV antibodies in African bats suggests that they might play a role in the EBV reservoir. Moreover, African bats also carry other potentially zoonotic agents such as Henipah‐like viruses, coronaviruses and lyssaviruses. Today only little information is available on interactions between humans and bats. The objective of our exploratory study was to describe the extent and modes of contacts between humans and bats in southern Cameroon, considered as an area at risk for future EBV outbreaks. The survey was conducted in 11 villages of four distinct rural areas in southern Cameroon. A total of 135 respondents were interviewed using semi‐structured questionnaires, between February and May 2017. The study showed that direct contacts between bats and humans are relatively common. Bat bushmeat appeared to be an occasional meat resource; 40% of respondents consume bats with a median annual consumption of three, and 28% of respondents hunt them. About 22% of the respondents reported children catching bats. Indirect contact also appeared to be common; 55% of hunters use caves as shelters and 67% of interviewees eat fruits previously chewed by bats. Bat consumption varied significantly between regions (from 0% to 87%) and between pygmies and bantus in the extreme south‐east of Cameroon. The study revealed considerable diversity in practices among interviewees, most of them being subsistence cultivators and relying on self‐hunted bushmeat. Geographical diversity of contacts and perceptions regarding bats in Cameroon emphasizes the need to adjust zoonotic pathogen surveillance and education campaigns to the specificities of the communities and their context of interaction with wildlife. 相似文献
18.
为研究崂山奶山羊永生化骨髓间充质干细胞(BMSCs)的诱导分化潜能,采用P3代BMSCs和P30代TERT-BMSCs进行体外成脂和成神经诱导分化。结果显示,当细胞传至P30代时,TERT-BMSCs生长旺盛;在成脂诱导后,P3代BMSCs和P30代TERT-BMSCs均能观察到细胞中透明脂滴的形成,油红O染料染色后可见脂滴被染成红色;在成神经诱导后,P3代BMSCs和P30代TERT-BMSCs均能形成树突样或三角形的形态,甲苯胺蓝染色后可观察到细胞中尼氏体的存在。综上提示,永生化的崂山奶山羊BMSCs在多次传代后仍具有较强的多向诱导分化能力,这为永生化MSCs的广泛应用提供了理论依据。 相似文献
19.
千烟洲灌木生物量模型研究 总被引：14，自引：0，他引：14
采用模型分析法研究了千烟洲试验站白马骨、美丽胡枝子、三叶赤楠、黄栀子四种灌木生物量与地径D、高度H、冠幅C的相关关系。对灌木树种生物量的相对生长研究表明：W=a＋b（D^2H）＋c（D^2H）^2、W=a（D^2H）b、W=a＋bD＋cC＋dH、w=a＋b（CV）＋c（CV）^2可较好地描述灌木树种个体总生物量、枝生物量、叶生物量及根生物量与各形态因子的相关关系。在群落学调查中测定灌木生物量时，利用投影体积CV构建的生物量模型W=a＋b（CV）＋c（CV）^2、W=a（CV）b可用来估算四种灌木的总生物量及各器官生物量。 相似文献
20.
自然发酵酸菜汁中乳酸菌的分离、鉴定 及发酵剂的筛选 总被引：21，自引：0，他引：21
从自然发酵酸菜汁中可以分离出许多优良菌株。本试验成功地分离出一株乳酸球菌（代号为L）,经初步鉴定属于明串珠菌属,并进行了部分生理特点试验,用其发酵白菜,显示出发酵补期生长快、产酸率高、风味柔和的特点。将其与已应用于发酵酸白菜中的两株乳酸杆菌（代号为1681,1047）组成不同配比的发酵剂发酵白菜,根据pH值、可滴定酸及感官指标的等综合评定,确定L:1681=1:2,L:1047=1:2,1681:1047=1:2:1三种发酵剂接种发酵效果较好,pH值下降快,最终达3.5左右,且感官指标较好,可用于接种发酵酸白菜生产工艺中。 相似文献