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云南热带和亚热带山地森林鼠形啮齿类的群落结构 Ⅰ、多样性相,对丰盛度,密度和物量 总被引:3,自引:0,他引:3
热带山地雨林中捕获鼠形啮齿类6种,社鼠(Rattus niviventer)是优势种,相对丰盛度为81.18%;亚热带中山湿性阔叶林中捕获8种,中华姬鼠(Apodemus draco)为优势种,相对丰盛度为73.63%。两种森林类型鼠形啮齿类种类数目间并无显著差异。 热带山地雨林6种鼠形啮齿类平均密度为13.21只/公顷,平均生物量为711.43克/公顷;亚热带中山阔叶林中5种平均密度为20.25,平均生物量530.19。两种森林中鼠形啮齿类的平均密度差异显著,但生物量平均值却无明显差别。 群落中生物量分布极不均匀,社鼠和中华姬鼠的生物量分别在两种森林中各自占鼠形啮齿类总生物量的77.37%与70.43%。 相似文献
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小哺乳动物身体元素组成的研究 总被引:1,自引:0,他引:1
以小哺乳动物为研究对象,讨论引起动物体元素含量变化的因素,估计各化学元素的现存量,计算原子比率,比较动物种间元素含量的差异,预测动物身体各元素含量,计算动物粪便沉积在不同植物群落中的量,这对生态系统中不同营养层间物质循环的研究,对评价动物在生态系统的元素循环中作用具有理论意义。 相似文献
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本文分析、计算了中华姬鼠和中华qu的氮、磷、钾、钠、钙、镁、钡、铝、铁、铜和锌的含量及原子比率。发现除氮外,其它元素含量均有种间差异。此外,估算了10个元素的现存量。 相似文献
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杉木人工林生态系统水文学过程的养分特性 总被引:2,自引:0,他引:2
根据5a定位观测的数据,对湖南会同24~28a生的杉木人工林生态系统各水文学过程中的养分特性进行了研究。结果表明:林冠降水是杉木人工林生态系统养分输入的重要来源,其中Ca的养分含量最高,P的含量最低。林内穿透水各养分元素的含量明显高于林冠降水中养分的含量。除Ca外,树干茎流中其它养分元素的含量为林冠降水的6倍以上。可见,林内穿透水和树干茎流是杉木林生态系统内养分循环的重要组成部分,有利于提高系统的养分利用率。地表径流中除硝态氮外,各元素的含量与穿透水的含量接近,其中P、Na和K三种元素的含量较低,但未超过林冠降水中养分元素含量。地下径流中N和K的含量较低,而Ca的含量与林冠降水相比没有差异。因而地表径流和地下径流不可避免的造成生态系统的养分损失,但24~28a生杉木林生态系统的调控能力较强,地表径流和地下径流量较小,生态系统的养分损失也相对较小,养分为净积累。不同季节之间水文学过程中养分元素含量存在一定程度的差异。降水形态、雷电和地形等要素影响养分元素含量。硝态氮在冰雹中未检出,而在雨水中的含量是雪水的2倍。铵态氮、K和Mg等元素在雨水中的含量最高。P和Ca以雪水的含量最高,与雨水和冰雹相比不存在数量级差异。雷电明显增加降水中养分的含量,特别是林冠上层的低空放电使降水中N的含量增加3~5倍。由于山谷和山麓的立地条件较好,其穿透水中养分含量比山坡的高,山谷与山麓的大致相等。在采集水样进行养分分析时,应考虑降水时间、降水形态和地形等因子的影响。 相似文献
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甘南高寒草甸植物元素含量与土壤因子对坡向梯度的响应 总被引:1,自引:0,他引:1
通过测定甘南高寒草甸不同坡向条件下25科86种植物叶片氮(N)、磷(P)、钾(K)含量、有机碳(C)含量、叶片含水量和相对叶绿素(SPAD)值,以及不同坡向的土壤含水量、有机碳、全氮、全磷含量等土壤指标,分析了不同坡向植物叶片元素含量与土壤环境因子之间的关系。研究结果表明,在南坡-北坡梯度上,随着土壤含水量的增加,植物叶片P含量、叶K含量和叶片含水量显著增加,而相对叶绿素显著降低。土壤养分含量与植物叶片P、叶K含量和叶含水量显著正相关,与叶片相对叶绿素显著负相关。说明不同坡向条件下叶片养分含量受土壤因子的影响显著,土壤的水分及养分状况对植物叶片元素含量的贡献不同。土壤含水量是坡向梯度上影响植物叶片特征的最主要因子。坡向梯度上土壤含水量对植物叶片各种元素含量的影响和植物叶片含水量对不同土壤因子的响应模式支持了生长在南坡的植物能以提高水分和养分利用效率而适应南坡较为干旱和贫瘠的生境。 相似文献
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A simple, inexpensive acrylate polymer which has a capacity to absorb 170 ml of water per g has been developed. It can be used to concentrate dilute solutions of macromolecules such as proteins, nucleic acids, and carbohydrates. The polymer absorbs only low-molecular-weight substances such as glucose, sucrose, and inorganic salts. It can replace the various conventional concentration methods. No special device or electricity is needed for the concentration. The inexpensive polymer, molded in the form of rods, can be very conveniently used as “disposable concentration sticks.” 相似文献
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Thevissen K Pellens K De Brucker K François IE Chow KK Meert EM Meert W Van Minnebruggen G Borgers M Vroome V Levin J De Vos D Maes L Cos P Cammue BP 《Bioorganic & medicinal chemistry letters》2011,21(12):3686-3692
A series of substituted benzylsulfanyl-phenylamines was synthesized, of which four substituted benzylsulfanyl-phenylguanidines (665, 666, 667 and 684) showed potent fungicidal activity (minimal fungicidal concentration, MFC ? 10 μM for Candida albicans and Candida glabrata). A benzylsulfanyl-phenyl scaffold with an unsubstituted guanidine resulted in less active compounds (MFC = 50-100 μM), whereas substitution with an unsubstituted amine group resulted in compounds without fungicidal activity. Compounds 665, 666, 667 and 684 also showed activity against single C. albicans biofilms and biofilms consisting of C. albicans and Staphylococcus epidermidis (minimal concentration resulting in 50% eradication of the biofilm, BEC50 ? 121 μM for both biofilm setups). Compounds 665 and 666 combined potent fungicidal (MFC = 5 μM) and bactericidal activity (minimal bactericidal concentration, MBC for S. epidermidis ? 4 μM). In an in vivo Caenorhabditis elegans model, compounds 665 and 667 exhibited less toxicity than 666 and 684. Moreover, addition of those compounds to Candida-infected C. elegans cultures resulted in increased survival of Candida-infected worms, demonstrating their in vivo efficacy in a mini-host model. 相似文献
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为了适应临床依靠药敏试验而指导临床选择用药的快速要求,我们研制的一次性细菌M IC 测定装置,以确保药敏试验结果的准确性。一次性细菌的M IC 测定装置经国际标准菌株的检测,结果证实这些国际标准菌株的M IC 都在允许范围内,由此验证一次性细菌M IC 测定装置是可靠的,这种装置还具有易读、重复性好的特点,在完成M IC 检测后还可以进行M BC 的检测,值得临床推广使用 相似文献
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不同CO_2浓度与温度条件下马铃薯叶片的淀粉浓度与比叶重和矿质元素浓度的关系(英文) 总被引:1,自引:0,他引:1
三个马铃薯(Solanum tuberosum L.)品种在500、1000、1500、2000μmol·mol~(-1)CO_2浓度与16、20℃空气温度下生长35d,测定了植株叶片的比叶重(g·m~(-2))、淀粉浓度及主要养分N、P、K、Ca、Mg的浓度。在16℃和20℃下,叶片淀粉浓度随CO_2浓度的增加而增加,且16℃下的测定值高于20℃下的测定值。比叶重与以叶面积或干重为基础的叶片淀粉浓度成正相关。叶片N、P、Ca、Mg浓度与14%范围内的淀粉浓度成负相关,但与高于14%的淀粉浓度无明显关系。去除淀粉效应后的比叶重及叶片养分浓度呈现类似的变化趋势。然而,不同CO_2浓度下的叶片K浓度相对稳定,因此受淀粉浓度影响较小。研究结果表明,不同CO_2浓度与温度条件下马铃薯叶片的比叶重及N、P、Ca、Mg浓度的变化不完全是叶片淀粉浓度的变化所致。 相似文献
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Foliar concentrations of starch and major nutrients N, P, K, Ca, and Mg along with specific leaf weight (SLW) were determined in the potato (Solaruan tuberosum L. ) cvs "Denali", "Norland” and "Russet Burbank" grown for 35 days under the CO2 concentrations of 500, 1 000, 1 500 and 2 000 μmol' mol-l at both 16 and 20 ℃ air temperature. The starch concentration, pooled from the three cuhivars, increased with increasing CO2 concentration at both 16 and 20 ℃, and was consistently higher at 16 ℃ than at 20 ℃. The SLW (g·m-2) was positively related to the foliar starch concentration on the basis of leaf area or dry weight. The concentrations of N, P, Ca, and Mg in leaves were negatively related to starch concentration under 14% starch on a dry weight basis. Above 14%, there was no significant relationship between nutrient and starch concentrations. The similar patterns were seen when the SLW and nutrient concentrations were expressed on a starch-free basis. In contrast, the leaf concentration of K was not closely related to the starch concentration. The results indicated that the changes in SLW and concentrations of N, P, Ca, and Mg in potato leaves only partially resulted from the changed starch concentration. 相似文献
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Uetani M Kobayashi E Suwazono Y Nishijo M Nakagawa H Kido T Nogawa K 《Biological trace element research》2006,110(2):107-117
We examined how the influence of smoking on blood and urinary cadmium (Cd) concentrations was modified by the level of environmental
Cd. We measured blood and urinary Cd concentrations of 1134 men over 50 yr of age in three areas in Japan that were exposed
to different levels of environmental Cd. Analysis of variance was used to compare Cd concentrations in blood and urine of
smokers with those of nonsmokers living in the three areas. Correlation coefficients between the number of cigarets smoked
per day or smoking indices (the number of cigarets smoked per day multiplied by the number of years smoked) and blood and
urinary Cd concentrations were calculated. No significant difference in Cd concentrations between smokers and nonsmokers was
observed in areas where the average Cd concentration in blood was over approx 2.4 ng/g, 2.0 μg/L in urine, and 2.3 μg/g creatinine
in urine, respectively. Therefore, it was suggested that an influence of smoking on blood and urinary Cd concentrations was
not observed in areas exposed to relatively high levels of environmental Cd. 相似文献
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P.M. Holowecky R.R. James D.P. Lorch S.E. Straka H.D.A. Lindquist 《Journal of applied microbiology》2009,106(3):738-747
Aims: To determine the efficiency of various ultrafiltration cartridges (UFC) in concentrating test micro-organisms from drinking water.
Methods and Results: Replicate drinking water samples from three potable water supplies were dosed with Bacillus anthracis Sterne, Francisella tularensis LVS, Yersinia pestis CO92, bacteriophages MS2 and phi-X174, and Cryptosporidium parvum. The test micro-organisms were dosed together in 100 l of water, which was then recirculated through one of five different UFC until the retentate volume was reduced to c. 500 ml. The micro-organisms were assayed before and after ultrafiltration concentration and per cent recoveries were calculated. There were nine statistically significant differences among pairs of filters out of a possible 180 different combinations of UFC, test micro-organisms, and water types.
Conclusions: No filter consistently performed better or worse than the others for each test micro-organism in all water samples tested.
Significance and Impact of the Study: This study provides performance data on the ability of several different UFC to concentrate a panel of test micro-organisms from three sources of potable water. Water utilities and first responders may use these data when selecting UFC for use in emergency response protocols. This study also provides additional data as to the efficacy of ultrafiltration for recovering bacteria, virus-like particles, and protozoan oocysts from water samples. 相似文献
Methods and Results: Replicate drinking water samples from three potable water supplies were dosed with Bacillus anthracis Sterne, Francisella tularensis LVS, Yersinia pestis CO92, bacteriophages MS2 and phi-X174, and Cryptosporidium parvum. The test micro-organisms were dosed together in 100 l of water, which was then recirculated through one of five different UFC until the retentate volume was reduced to c. 500 ml. The micro-organisms were assayed before and after ultrafiltration concentration and per cent recoveries were calculated. There were nine statistically significant differences among pairs of filters out of a possible 180 different combinations of UFC, test micro-organisms, and water types.
Conclusions: No filter consistently performed better or worse than the others for each test micro-organism in all water samples tested.
Significance and Impact of the Study: This study provides performance data on the ability of several different UFC to concentrate a panel of test micro-organisms from three sources of potable water. Water utilities and first responders may use these data when selecting UFC for use in emergency response protocols. This study also provides additional data as to the efficacy of ultrafiltration for recovering bacteria, virus-like particles, and protozoan oocysts from water samples. 相似文献
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Rajabi L Courreges C Montoya J Aguilera RJ Primm TP 《Letters in applied microbiology》2005,40(3):212-217
AIMS: Mycobacteria are a serious cause of infections in humans, with limited treatment options, as no new antibiotics have been developed against mycobacteria since the 1960s. In this study, the antimycobacterial activity of a small library of acetophenone (AP) compounds was analysed. METHODS AND RESULTS: Twenty-three AP derivatives were examined for activity against mycobacteria using a microbroth assay. The compounds were bacteriostatic, with the most effective (cyclohexylacetophenone and piperidinoacetophenone) having minimal inhibitory concentrations of 246 microM. Active compounds tended to be more hydrophobic, and may work by alkylation of as yet undetermined intracellular target protein(s). Cytotoxicity against eukaryotic cells was also determined and appears to be unrelated to the bacteriostatic activity. SIGNIFICANCE AND IMPACT OF THE STUDY: AP may serve as a novel group of useful therapeutics against the mycobacteria. 相似文献