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Abstract. A new method is described for measuring tree height in tropical forest with a dense undergrowth, the so-called angles-measure method, which is related to the height-matching method formerly used by British foresters. 相似文献
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四种提取芸芥基因组DNA方法的比较 总被引:4,自引:0,他引:4
以芸芥为材料 ,分别用CTAB法、SDS法、尿素法、NaOH法四种方法对芸芥基因组DNA进行了提取 ;并用紫外光分光光度计法、琼脂糖电泳法和RAPD分析法对所提取的DNA进行检测 ,将它们在DNA的产量、质量和耗时、耗费等方面的优缺点进行比较 ,以便在实际工作中根据不同的试验条件选取最合适的提取方法。通过四种方法的比较 ,研究认为尿素法是芸芥基因组DNA的最佳提取方法。 相似文献
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目的:研究提取不同时期小麦网腥黑粉菌冬孢子总DNA的最佳方法。方法:应用改良过的四种方法(CTAB法、SDS-CTAB法、SDS法和尿素法)对小麦网腥黑粉菌冬孢子总DNA进行提取。结果:提取当年小麦网腥黑粉菌冬孢子DNA,纯度(OD260/OD280):CTAB法〉SDS-CTAB法〉SDS法〉尿素法=1.876〉1.7815〉1.7789〉1.6095;产率(μg/g):SDS-CTAB法〉SDS法〉尿素法〉CTAB法=796.25〉664〉306〉291.5。提取15年的小麦网腥黑粉菌冬孢子DNA,纯度(OD260/OD280):CTAB法〉SDS-CTAB法〉SDS法〉尿素法=1.91795〉1.8876〉1.65985〉1.55925;产率(μg/g):尿素法〉CTAB法〉SDS法〉SDS-CTAB法=1529.25〉799〉687.25〉372.5。结论:SDS-CTAB法是提取当年小麦网腥黑粉菌冬孢子DNA的最佳方法。CTAB法是提取15年的小麦网腥黑粉菌冬孢子DNA的最佳方法。 相似文献
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Gary A. Sod 《Journal of mathematical biology》1986,24(3):279-289
A numerical method is presented for the solution of reaction diffusion systems in biology. The method is used to re-examine the oxygen diffusion in a spherical cell with the Michaelis-Menten oxygen uptake kinetics. 相似文献
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Rooting measurements have been made at different growth stages for sugar beets (1987) and for cereals (1988) on three different sites using four different root measurement techniques: (a) the core method where roots were extracted and root length is directly measured, (b) the core-break method where the visible roots were counted on the faces of a broken soil column, (c) the trench profile wall method where the number of visible roots were counted and the root length density was estimated on a profile wall, and (d) the monolith method where the roots were extracted from monoliths dug out from a profile wall. The calibration curves between the field methods and the extraction methods were not linear, and regression coefficients differed significantly between different sites, crops and between fields with different agronomic management, e.g. irrigation and liquid manure application. Differences between growth stages were comparably low compared with those found between locations. Root length densities obtained with the trench profile method were on average 10-fold lower in the sand brown earth, 6-fold lower in the vertisol and 4 times lower in the cambisol compared to data obtained with the core method. It is therefore concluded that the core-break method and the trench profile wall method deliver no reliable data for comparing rooting intensities between different soils and between different crops if they are not calibrated with an extraction method for each site and crop. 相似文献
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参考国内外昆虫基因组DNA提取的常用方法,选取KAc法、氯仿-异戊醇法和盐析法3种方法对苹果绵蚜(Eriosoma lanigerum)基因组DNA进行提取.通过基因组DNA直接琼脂糖凝胶电泳、SSR引物扩增产物的琼脂糖凝胶电泳和聚丙烯酰胺凝胶电泳检测,对3种方法所提基因组DNA的质量进行了比较,并综合分析了提取所需时间及所用试剂的毒性大小等.结果表明,盐析法操作程序较简便快捷,节时省工,可得较好质量的DNA样本,且对试验操作人员无伤害,是一种值得推广应用的基因组DNA提取方法. 相似文献
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The aim of this study is to investigate whether Pythium guiyangense,a mosquito-killing fungus isolated in Guiyang,Guizhou Province of China in 1994,is pathogenic to plants.Six common crops,Cucumis sativa,Lycopersicon esculentum,Capsicum annuum,Nicotiana tabacum,Brassica campestris and Oryza sativa were used as subjects for test.Zoospores of the fungus were used to infect the plants with soil inoculation method,caudex injection method and foliage spray method.Both positive control(using P.aphanidermatum)and negative control(using sterile water)were set up in all the experiments.The results showed that no infection was found on the tested plants in soil inoculation experiments.In caudex injection test,callus grew around the wounded tissue in most of the plants.Brownish rottenness could be found only in the injected wounds in a few plants,probably caused by saprophytic bacteria or other fungi,and the germ-carrying plants grew normally.No abnormal appearance was found on the six crops in foliage spray test.It was demonstrated that P guiyangense could hardly infect plants in nature,and was a safe and promising agent for mosquito biological control. 相似文献
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Several non-Ewald methods for calculating electrostatic interactions have recently been developed, such as the Wolf method, the reaction field method, the pre-averaging method, and the zero-dipole summation method, for molecular dynamics simulations of various physical systems, including biomolecular systems. We review the theories of these approaches and their potential applications to molecular simulations, and discuss their relationships. 相似文献
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Dinesh D. Vaishnav Eric T. Korthals 《Journal of industrial microbiology & biotechnology》1991,8(3):209-212
Summary Degradation of 10 organic chemicals by pre-acclimated microorganisms in BOD dilution water was determined directly by UV spectrophotometry and indirectly by a modified BOD method. Residual chemical concentrations were periodically measured and pseudo-first-order biodegradation rate constants (k
1) were calculated. Thek
1 spectrophotometry values ranged from 0.006/h to 0.077/h andk
1-BOD values from 0.002/h to 0.043/h for 1-methylnaphthalene and indole, respectively. The ratios ofk spectrophotometry to k1-BOD were between 1.5 for salicylic acid and 3.0 for 1-methylnaphthalene with a mean of 2.7. A significant (=0.001) linear correlation (r
2=0.854,F=46.630) existed between the two sets of rate constants. Results from this study suggest that the modified BOD method may be used to estimate chemical biodegradation rates in synthetic media. 相似文献
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呼肠孤病毒科的系统发育分析 总被引:1,自引:0,他引:1
运用邻接法(neibor-joining,NJ)、最大似然法(maximum likehood,ML)对国际病毒分类委员会(Intemational Committee on Taxonomy of Viruses,ICTV)第八次报告中所有已报道的呼肠孤病毒科外层衣壳蛋白序列进行了系统发育分析.结果表明:两种方法构建的系统树拓扑结构基本一致,尽管部分分支略有差异,但都能够反映出科内各属的系统发育关系,分析结果支持了该科的分类地位.同时还比较两种建树方法的异同点,并对建树产生的差异原因作了探讨. 相似文献
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采用α-脱氧核糖法、邻苯三酚自氧化法、DPPH法、铁氰化钾还原法等4种国内外常用的体外抗氧化活性检测方法,对鄂西北产鱼腥草石油醚提取物、无水乙醇提取物、乙酸乙酯提取物、三氯甲烷提取物的抗氧化性进行化学评价,结果表明鱼腥草提取物具有一定抗氧化性,其浓度与其抗氧化活性强弱顺序一致。 相似文献
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The aim of this study is to investigate whether Pythium guiyangense, a mosquito-killing fungus isolated in Guiyang, Guizhou Province of China in 1994, is pathogenic to plants. Six common crops, Cucumis sativa, Lycopersicon esculentum, Capsicum annuum, Nicotiana tabacum, Brassica campestris and Oryza sativa were used as subjects for test. Zoospores of the fungus were used to infect the plants with soil inoculation method, caudex injection method and foliage spray method. Both positive control (using P. aphanidermatum) and negative control (using sterile water) were set up in all the experiments. The results showed that no infection was found on the tested plants in soil inoculation experiments. In caudex injection test, callus grew around the wounded tissue in most of the plants. Brownish rottenness could be found only in the injected wounds in a few plants, probably caused by saprophytic bacteria or other fungi, and the germ-carrying plants grew normally. No abnormal appearance was found on the six crops in foliage spray test. It was demonstrated that P. guiyangense could hardly infect plants in nature, and was a safe and promising agent for mosquito biological control. 相似文献
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蚯蚓野外采样方法评述 总被引:1,自引:0,他引:1
蚯蚓作为土壤生态系统的关键组成部分,不但可以改善土壤结构,而且与许多生物化学养分循环直接相关,对土壤质量改善和土壤生产力提高起到至关重要的作用.然而,蚯蚓野外采样方法的系统研究和评估还比较缺乏,在国内尤其少见.本文综述了目前国内外常见蚯蚓野外采样方法的操作过程、优缺点、有效性以及对蚯蚓种群特征研究结果可能产生的影响,认为在允许扰动土壤的区域,利用驱虫剂与手拣法相结合进行蚯蚓采样能够较为准确地反映蚯蚓种群和生物量的真实特征;在不能扰动土壤的区域异硫氰酸烯丙酯(AITC)溶液方法是最佳选择. 相似文献
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Anna Mika Ewa Kmiecik Arkadiusz Krawiec Mihai Zamfir Aneta Chochorek 《Geomicrobiology journal》2019,36(5):460-467
The aim of the study was to check the occurrence of Legionella pneumophila in thermal water and to compare different analytical methods of its determination and/or quantification used in different laboratories. The research has shown that there are noticeable differences between results from culture method, qPCR, and FISH. Significant influence on the results has got analysts qualification, samples preparation, and equipment parameters. Very important is also the homogeneousness of the samples. qPCR or FISH method can be used as a preliminary, quick study, for identification of Legionella in water samples but the results obtained should be confirmed by culture method. 相似文献
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Steven C. Josephson Kenneth E. Juell Alan R. Rogers 《American journal of physical anthropology》1996,100(2):191-206
Estimating the degree of sexual dimorphism is difficult in fossil species because most specimens lack indicators of sex. We present a procedure that estimates sexual dimorphism in samples of unknown sex using method-of-moments. We assume that the distribution of a metric trait is composed of two underlying normal distributions, one for males and one for females. We use three moments around the mean of the combined-sex distribution to estimate the means and the common standard deviation of the two underlying distributions. This procedure has advantages over previous methods: it is relatively simple to use, specimens need not be assigned to sex a priori, no reference to living species analogs is required, and the method provides conservative estimates of dimorphism under a variety of conditions. The method performs best when the male and female distributions overlap minimally but also works well when overlap is substantial. Simulations indicate that this relatively simple method is more accurate and reliable than previous methods for estimating dimorphism. © 1996 Wiley-Liss, Inc. 相似文献