排序方式： 共有47条查询结果，搜索用时 215 毫秒
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Nasrin SULTANA Jun ZHAO Yuanfeng CAI G. K. M. Mustafizur RAHMAN Mohammad Saiful ALAM Mohammad FAHEEM Adrian HO Zhongjun JIA 《土壤圈》2022,32(2):348-358
Biological methane oxidation is a crucial process in the global carbon cycle that reduces methane emissions from paddy fields and natural wetlands into the atmosphere.However,soil organic carbon accumulation associated with microbial methane oxidation is poorly understood.Therefore,to investigate methane-derived carbon incorporation into soil organic matter,paddy soils originated from different parent materials(Inceptisol,Entisol,and Alfisol) were collected after rice harvesting from four major rice-producing regions in Bangladesh.Following microcosm incubation with 5%(volume/volume)13 CH4,soil13 C-atom abundances significantly increased from background level of 1.08% to 1.88%–2.78%,leading to a net methane-derived accumulation of soil organic carbon ranging from 120 to 307 mg kg-1.Approximately 23.6%–60.0% of the methane consumed was converted to soil organic carbon during microbial methane oxidation.The phylogeny of13 C-labeled pmoA(enconding the alpha subunit of the particulate methane monooxygenase) and 16 S rRNA genes further revealed that canonical α(type II) and γ(type I) Proteobacteria were active methane oxidizers.Members within the Methylobacter-and Methylosarcina-affiliated type Ia lineages dominated active methane-oxidizing communities that were responsible for the majority of methane-derived carbon accumulation in all three paddy soils,while Methylocystis-affiliated type IIa lineage was the key contributor in one paddy soil of Inceptisol origin.These results suggest that methanotroph-mediated synthesis of biomass plays an important role in soil organic matter accumulation.This study thus supports the concept that methanotrophs not only consume the greenhouse gas methane but also serve as a key biotic factor in maintaining soil fertility. 相似文献
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赣中丘陵地区广泛分布着由第四纪红土发育的水稻土,它是重要的产粮地区,也是低产田分布较广的地区。提高低产的红壤性水稻土的肥力,一向是大家所关心的问题,各有关单位做了不少的研究。关于红壤性水稻土的结构特性及胶结物质等曾有研究[1,9],但对结构形成具有重要意义的微团聚体的特性及其与农业措施的关系,研究较少。土壤微团聚体质和量的研究,可分别土壤肥力的高低,也可阐明輪作、耕作和施肥等措施在培肥中的作用。作者[4,6]曾进行中性水稻土有机矿质复合体的研究,在此基础上,本文拟就红壤性水稻土中微团聚体1)的特性及其与土壤肥力的关系作一初步了解,为进一步开展这方面的研究提供线索。 相似文献
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N Martin T Höftmann E Politt HO Hoppen M Sohr AR Günzel-Apel A Einspanier 《Reproduction in domestic animals》2009,44(S2):185-189
Different abortifacient regimes in dogs were analysed for their effect on the pregnancy corpora lutea (CL), namely, prostaglandin F2a analogue cloprostenol (CLO) combined with dopamine agonist cabergoline (CAB), or progesterone (P4) receptor antagonist aglepristone (AGL). Ovaries were collected after 6-10 days of treatment during first trimester. The CL of the control-group showed strong expression of relaxin (RLX), its receptor RXFP1 and enzymes of steroid biosynthesis (HSD) with high peripheral P4-levels. Whereas RXL, RXFP1 and HSD were lowest expressed in the CLO/CAB-group with a massive degeneration of CL and their blood vessels combined with low peripheral P4-level. The AGL-group showed less extensive CL degeneration and more intensive staining of the examined factors than CLO/CAB. In summary, all examined factors are associated with normal luteal function and are useful tools to stage luteolysis. Although both treatments have the same abortive action, their sequence of events on the CL is different. 相似文献
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为解决若干病原菌引起的西番莲茎基腐病症状类似,难从症状方面辨别病原菌的问题,采用经典方法即常规鉴定法,对引起海南省琼海市西番莲基腐的病原菌进行鉴定。配制选择性PDA、PDA、V-8、选择性V-84种培养基,对样本中的病原物进行分离、纯化,根据分离菌的各项形态特征描述和分离菌株的主要生长温度测定结果,以及有关文献提供的原理方法进行该分离菌鉴定。结果表明:①分离到1种疫霉菌菌株;②该菌株在选择性PDA、PDA、选择性V-8培养基生长的诸方面特征一样。菌落圆形均一,气生菌丝不丰富。孢子囊形态为侧梨形、柠檬形或椭圆形,基部钝圆,长×宽为24.5～44.3μm×22.8～34.5μm,冷冻后释放游动孢子,未见厚垣孢子。③菌株最低生长温度8～10℃,最适生长温度28℃,最高生长温度36～40℃。④28℃下,分离菌在V-8上日生长量为16.2mm,而在PDA上则为13.7mm。⑤该病原物疫霉菌属于[Phytophthora nicotianae Breda de Haan(parasitica Dastur)]。 相似文献
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台湾目前对于阔叶树种的生长轮少有研究,尤其对于天然阔叶林的生长趋势与模型的相关研究更是缺乏,许多资料仍相当不足,有鉴于此,本研究将针对台湾中部地区的典型暖温带阔叶林进行生长轮的研究与探讨。神木溪保护林于2003年已设置完成18个长期观察的森林动态样区,本研究采用第13~18共6个样区内所有胸径大于6 cm之阔叶树,依据林分特征调查结果,钻取大于6 cm胸径林木,钻取高度约在胸径位置,共取得22科33属39种合计448支树芯。年轮分析运用实体显微镜配合CCD拍摄,目视各树种内年轮的变异,并加以分类,作为年轮目视判视与计数年轮的依据,并用Velmax系统量测年轮宽度,应用树冠级模式(CCM)、定期生长量模式(PAI)及混合模式(Mixed)建立各冠层生长趋势,并解析各树种树龄结构,以提供台湾最大面积、分布最广之楠槠及栎林带林分经营之参考。年轮特征上,属于散孔材树种占79%;半环孔材树种占18%;环孔材树种占3%。生长趋势上,所有树种的平均生长速率统计结果为3.53 mm/a。冠层产生垂直层次分化作用明显,显示出其生长的趋势,上主冠层直径增长情形最快,平均生长率为4.47 mm/a;主冠层其次,平均生长率为2.95 mm/a;底冠层速率最慢,平均生长率为2.92 mm/a。PAI模式显示大部分树种的生长趋势是呈现年轮宽度随树龄增加而增加或线性常数的情形。树龄估算以树冠级模式、PAI模式和混合模式3种模式估算,全部平均年龄分别为55、60、59年。混合模式的利用可以降低单独使用树冠级模式或PAI模式的误差率。树龄结构上,依树冠级模式、PAI模式及混合模式龄级分布结果,本样区充满耐阴性树种前生苗与灌木,逐渐形成典型的复层林。树龄出现2种分群,第1种大多为耐阴性树种的小苗,树木建立时间为20世纪后期;第2种在1900年左右形成了1个独立的单峰。年轮不明显区别造成类型分类的困难,轮宽不规则也无法明确定年,PAI模式需要大量的各龄阶树芯数据建立回归模式,所得到的模型才具有足够之代表性,混合模式虽解决了部分树龄推估的误差,但仍有其他问题,因此日后应更进一步进行探讨与分析,方能对森林生态系之永续经营与发展产生一定程度的帮助。本研究提供暖温带阔叶林林分径向生长与树龄结构信息,以供森林收获采伐和森林永续经营参考。 相似文献
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MB Koivisto F Eschricht C Urhausen HO Hoppen M Beyerbach CHY Oei AR Günzel-Apel 《Reproduction in domestic animals》2009,44(S2):320-325
Effects of a short-term hyper- and hypoprolactinaemia on serum concentrations of LH, testosterone and semen quality in six male Beagles were investigated. Blood samples were collected at 3-day intervals for 12 weeks. The time span was divided into five 3-week periods: pre-treatment, metoclopramide (MCP) treatment (0.2 mg/kg orally three times daily), cabergoline (CAB) treatment (5 μg/kg orally once daily), post-treatment 1 and post-treatment 2. In the latter, only semen characteristics were evaluated. Semen parameters were analyzed once per week during the whole 15-week investigation time. At the end of each period, the effects of a single intravenous injection of thyrotropin-releasing hormone (TRH; 10 μg/kg) on the secretion of prolactin (PRL), LH, testosterone, thyroid-stimulating hormone and thyroxine (T4) were investigated. Pre-treatment serum PRL concentration increased under MCP (p < 0.05), followed by a decrease under CAB administration (p < 0.05). Luteinizing hormone and testosterone concentrations were not affected. Except for straight-line sperm velocity, semen quality did not differ between collection periods. A single iv TRH injection induced a significant PRL increase at 20 min in all experimental periods except during CAB treatment. Luteinizing hormone and testosterone did not show clear TRH-related changes. Basic T4 levels were significantly reduced after CAB treatment (p < 0.05). The results of the present study demonstrate that MCP-induced short-term hyperprolactinaemia in male beagles does not seriously affect the hypothalamo-pituitary axis and semen quality. 相似文献
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