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严文达 《新农村(黑龙江)》2013,(8):128-128
水稻测土配方施肥是根据土壤供肥性能、水稻需肥规律与肥料效应,在施用有机肥的基础上,提出氮、磷、钾和微肥的用量。以下本文对测土配方施肥定义、优势、施肥原则及技术等进行了阐述与分析。 相似文献
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安徽省水稻化肥用量偏大,氮肥用量偏高现象普遍。通过田间示范,综合比较不同品种配方肥对作物生长情况、产量、经济效益、肥料投入产出比等指标,客观评价测土配方施肥效益,为测土配方施肥技术参数的校正及进一步优化肥料配方提供依据,也为生产上大面积推广节肥减肥新技术产品提供依据。 相似文献
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不同用量有机肥配施化肥对水稻生长及产量的影响 总被引:2,自引:0,他引:2
为明确有机肥在水稻生产中的最适用量,本文采用小区试验法,施用自主发酵有机肥,有机肥用量为2.5,7.5,15.0,22.5 t·hm~(-2)四个水平,研究不同用量有机肥配施化肥对水稻生长及产量的影响。结果表明:有机肥配施化肥能促进水稻分蘖,植株长势在分蘖期-幼穗分化期弱于常规施肥,在抽穗-灌浆期则优于常规施肥,主要表现在增加了干物质积累、叶片数及叶面积,其中有机肥15.0 t·hm~(-2)+50%常规施肥、有机肥22.5 t·hm~(-2)+50%常规施肥与常规施肥处理间差异显著(P0.05);有机肥配施化肥延缓了抽穗进程,抽穗率在抽穗末期低于常规施肥;有机肥15 t·hm~(-2)+50%常规施肥较常规施肥增产4.7%,差异显著(P0.05),效果最佳。从经济效益值来看,有机肥用量越高,肥料成本越高,效益值越低,从提高产量、保证经济效益角度出发,有机肥15 t·hm~(-2)+50%常规施肥为最适配施用量。 相似文献
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我国主要砖茶中FAl等元素含量及其影响因素分析 总被引:2,自引:1,他引:2
为了解全国茶叶主产区砖茶中F、Al、Ca、Mg、Cu、Zn、Fe、Mn等主要元素的含量水平,在内蒙、甘肃、新疆、青海、四川等习惯饮用砖茶的地区收集了33份茶叶主产区砖茶样品,用燃烧水解-氟离子选择电极法对其进行氟含量的测定,同时用ICP-AES测定了砖茶中Al、Ca、Mg、Cu、Zn、Fe、Mn等生命元素的含量,并探讨了砖茶中F与其他元素的关系及其影响因素。结果表明,33份砖茶的F含量均值为431.92mg·kg^-1,Al、Ca、Mg、Cu、Zn、Fe、Mn含量分别是2237.88、6126.36、2163.01、19.00、29.73、633.88、1075.70mg·kg^-1;不同产地砖茶氟含量的差异比较明显,其中氟含量最低为74.1mg·kg^-1出现在云南省,最高为991.2mg·kg^-1出现在四川省;不同品种的砖茶氟含量也存在较大的差异,其中沱茶氟最低,其后依次为普洱茶、饼茶、茯砖、米砖、黑砖、青砖,最高的为康砖。多元回归分析表明砖茶中F与Al、Mn含量呈显著正相关(P〈0.05),与Zn呈显著负相关(P〈0.05),提示砖茶中的这些元素可能会影响氟中毒病情。 相似文献
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Neutron activation analyses of gallium, germanium, indium, and iridium in eight lunar samples and in meteorites and rocks (including four calciulnrich achondrites and five terrestrial basalts) with similar bulk compositions are reported. Lunar gallium concentrations are remarkably constant at about 5 parts per million, three times higher and four times lower than those in eucritic (calcium-rich) achondrites and terrestrial basalts, respectively. Lunar germanium concentrations range from = 0.04 to 0.4 part per million. Basaltic achondrites have similar germanium concentrations, whereas those in terrestrial basalts are uniformly higher at about 1.4 parts per million. Concentrations of indium in Ilunar samples range from 3 to 60 parts per billion, whereas those in terrestrial basalts are 80 to 100 parts per billion, and those in basaltic achondrites 0.4 to 3 parts per billion. Lunar iridium concentrations appear to be in the 0.1 to 10 parts per billion range. The Tranquillitatis samples are distinctly different from calcium-rich achondrites and terrestrial basalts. 相似文献
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ICP-OES法同时测定果蔬中铅、砷、镉、铬、铜、锡含量 总被引:2,自引:0,他引:2
果蔬样品经混酸消化后,控制一定的酸度,定容后应用等离子体发射光谱法(ICP-OES)对果蔬中铅、砷、镉、铬、铜、锡六种有害重金属进行测定,研究了分析测定条件,方法简单快速。测定结果表明,五种元素的加标平均回收率在91.0%~107%之间。其RSD均小于3.5%。按该方法进行处理及测定铅、砷、镉、铬、铜、锡,在选择的测定条件下最低检出限分别为0.0006 mg/kg、0.0003 mg/kg、0.00003 mg/kg、0.00005 mg/kg、0.00003 mg/kg、0.0006 mg/kg。 相似文献
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The finding of appreciable quantities of p,p'-DDT after feeding o,p'-DDT to rats led to the proposal of a theory, that an isomeric metabolic conversion occurs. The presence of p,p'-DDT as an impurity in supposedly pure samples of o,p'-DDT is the correct explanation for the appearance of p,p'-DDT. Purified o,p'-DDT and (14)C-labeled o,p'-DDT yielded no data to support the idea that o,p'-DDT is converted to the p,p'-DDT isomer. 相似文献
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Coulson T Catchpole EA Albon SD Morgan BJ Pemberton JM Clutton-Brock TH Crawley MJ Grenfell BT 《Science (New York, N.Y.)》2001,292(5521):1528-1531
Quantifying the impact of density, extrinsic climatic fluctuations, and demography on population fluctuations is a persistent challenge in ecology. We analyzed the effect of these processes on the irregular pattern of population crashes of Soay sheep on the St. Kilda archipelago, United Kingdom. Because the age and sex structure of the population fluctuates independently of population size, and because animals of different age and sex respond in different ways to density and weather, identical weather conditions can result in different dynamics in populations of equal size. In addition, the strength of density-dependent processes is a function of the distribution of weather events. Incorporating demographic heterogeneities into population models can influence dynamics and their response to climate change. 相似文献
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重金属稀土元素污染在水生物体内的生物富集 总被引:2,自引:0,他引:2
对铅、镉、汞以及镧、铈在鲤鱼体内的生物富集作用进行了室内试验和讨论。结果表明,重金属及稀土元素在鱼体各部位均有较强的富集作用,其中肌肉部分富集能力较弱,内脏富集能力最强;鱼体各部位对重金属及稀土元素的富集作用随时间的增加而增加,在一定的时间后趋于平衡;并且,鱼体中各部位对重金属及稀土元素的生物富集作用存在较大差异。 相似文献
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Structure, dynamics, and reactivity in hemoglobin 总被引:10,自引:0,他引:10
J M Friedman 《Science (New York, N.Y.)》1985,228(4705):1273-1280
The static structure of hemoglobin and its functional properties are very well characterized. It is still not known how energy is stored and used within the structure of the protein to promote function and functional diversity. An essential part of this question is understanding the mechanism through which the overall protein structure (quaternary structure) couples to the local environment about the oxygen binding sites. Time-resolved resonance Raman spectroscopy has been used to probe the vibrational degrees of the freedom of the binding site as a function of protein structure. Comparison of the spectra from both equilibrium and transient forms of deoxy hemoglobin from a variety of mammalian, reptilian, and fish hemoglobins reveals that for each quaternary structure there exist two tertiary states stabilized by the presence or absence of an iron-bound ligand. Pulse-probe Raman experiments show that for photodissociated, ligated hemoglobins the local tertiary structure relaxes at a solution-dependent rate extending from tens of nanoseconds to microseconds. In this local environment, the linkage between the iron and the proximal histidine proves to be the single observed structural feature that responds in a systematic and substantial manner to structural changes in the protein. The additional finding of a correlation between the frequency of the iron-proximal histidine stretching motion (nu Fe-His) and various parameters of ligand reactivity, including geminate recombination, implicates the associated localized structural element in the mechanism of protein control of ligand binding. On the basis of these and related finds, a model is presented to account for both coarse and fine control of ligand binding by the protein structure. 相似文献
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