期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
Frailty模型中累积风险估计的渐近性质
1
作者 唐碧海 《中山大学研究生学刊(自然科学与医学版)》 1994年第1期1-9,共9页
本文提出了 Frailty 模型下累积风险的央估计,并用央中心极限定理证明了此估计具有渐近正态性。所给估计具有显式表达式,比起已有的由 EM 算法给出的估计来,具有计算量少的优点。
关键词 渐近性质 Frailty模型 累积风险估计 央方法 异质性
下载PDF
Historical and Traditional Notes on Collecting Crop Genetic Resources in Central Part of Calabria Region
2
作者 Gina Maruca Gaetano Laghetti +2 位作者 Francesco Losavio Domenico Pignone Karl Hammer 《Journal of Environmental Science and Engineering(B)》 2013年第2期117-126,共10页
A collecting expedition has been carried out in the central part of Calabria region, south Italy; it has been concentrated on Reventino, Serre, Occitan and Albanian areas that were covered in certain coinciding sites ... A collecting expedition has been carried out in the central part of Calabria region, south Italy; it has been concentrated on Reventino, Serre, Occitan and Albanian areas that were covered in certain coinciding sites in the past. In totality, 50 accessions belonging to 14 taxa were collected from 8 collecting sites, representing mainly highly variable old landraces of vegetables and cereals and, especially, of pulses; most of them that appear severely threatened by genetic erosion are still cultivated, at certain level, by old farmers and directly used by their families. A comparison of the results of the previous missions that have been carried out in Calabria region that preserve valuable crop genetic resources on farm shows the large degree of genetic erosion for all crops collected. The results stressed the need to conserve a considerable amount of material endangered and the necessity of our ongoing care for their preservation either on farms or ex situ in genebanks. The complementarity of both conservation methods is needed. 展开更多
关键词 Genetic erosion CALABRIA on farm conservation genetic resources.
下载PDF
Modelling and process optimisation of antimony removal from a complex copper concentrate
3
作者 Samuel Ayowole AWE Mohammad KHOSHKHOO +1 位作者 Paul KRUGER ke SANDSTRM 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第3期675-685,共11页
The modelling and optimization for the alkaline sulphide leaching of a complex copper concentrate containing 1.69% Sb and 0.14% Sn were studied.Response surface methodology,in combination with central composite face-c... The modelling and optimization for the alkaline sulphide leaching of a complex copper concentrate containing 1.69% Sb and 0.14% Sn were studied.Response surface methodology,in combination with central composite face-centred design(RSM-CCF),was used to optimise the operating parameters.The leaching temperature,sulphide ion concentration and solid concentration were chosen as the variables,and the response parameters were antimony and tin recovery,and the time required to achieve 90% Sb dissolution.It was confirmed that the leaching process was strongly dependent on the reaction temperature as well as the sulphide ion concentration without any significant dependence on the solid concentration.Furthermore,a mathematical model was constructed to characterise the leaching behaviour.The results from the model allow identification of the most favourable leaching conditions.The model was validated experimentally,and the results show that the model is reliable and accurate in predicting the leaching process. 展开更多
关键词 alkaline sulphide hydrometallurgy ANTIMONY TETRAHEDRITE leaching optimization response surface methodology central composite face-centred design
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部