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751.
基于遗传算法的门限自回归模型在海温预测中的应用 总被引:4,自引:0,他引:4
提出了建立门限自回归模型(TAR)的一套简便通用的方法。用作者提出的改进遗传算法,可同时优化门限值和自回归系数,成功地解决了TAR建模过程所涉及的大量复杂寻优工作这一难题,为TAR模型的广泛应用提供了强有力的工具。实例计算的结果说明了这套方法的可行性和有效性,同时也说明了,通过门限值的控制作用,TAR模型可以有效地利用如海洋资源所隐含的时序分段相依性这一重要信息,限制了模型误差,从而保证了TAR模型预测性能的稳健性,提高了预测精度。该方法具有通用性,在各种非线性时序预测中具有重要的理论意义和应用价值 相似文献
752.
一个改进的农业生产函数模型:兼论遗传资源对江苏省农业经济增长的贡献 总被引:1,自引:0,他引:1
遗传资源是农业生产中重要的投入要素,通过将遗传资源投入纳入C-D生产函数模型,并对2001—2007年江苏省农业生产经济数据进行分析,计算江苏省遗传资源及其他生产要素对农业经济增长的贡献率。结果表明,江苏省农业经济增长主要依赖于动物遗传资源投入和科技进步。与固定资产和劳动力投入要素相比,遗传资源对农业经济增长的整体贡献明显,其中动物遗传资源的贡献高于植物遗传资源。因此,江苏省应优化农业结构,提高遗传资源利用率,加大科技投入,推进农业现代化建设。 相似文献
753.
Knowledge of total and bioavailable metal contents in soil is important for regional risk assessment and management. The main objective of the present study was to analyse the concentrations of metals in soils in two contrasting mining regions (Sudbury in Canada and Lubumbashi in DR-Congo). Genetic variation of plant populations was investigated to assess the potential impact of metal contamination on forest sustainability. The levels of copper, cobalt, zinc, arsenic, and lead were significantly higher (up to 200-fold) in mining sites in the Lubumbashi compared to the most highly contaminated Sudbury sites. The nickel content in soil samples from Lubumbashi was much lower compared to Sudbury region samples. Only 3.5% and 4 % of total copper and nickel, respectively, were phytoavailable, with values of 6%, 5.7%, 3.6%, and 5.4% for cobalt, magnesium, manganese, and zinc, respectively. There were significant positive correlations between total metal and phytoavailable metal concentrations for copper (r=0.99), nickel (r=0.86), cobalt (r=0.72), strontium (r=0.71), and zinc (r=0.66). Although genetic variation was high in Picea glauca populations from the Sudbury region, no association was found between metal contamination levels and genetic variation within and among the P. glauca populations. 相似文献
754.
采用随机扩增多态性DNA (RAPD)等技术,检测不同浓度镉(Cd)胁迫对菜豆幼苗叶片DNA损伤及相关生理特性的影响.结果表明,随着Cd处理浓度(0,20,40,80mg/L)的增加,菜豆幼苗中的Cd含量及叶片中丙二醛(MDA)含量升高;叶片中可溶性蛋白、脯氨酸、还原型谷胱甘肽在低浓度(20mg/L)Cd处理下含量增加,中、高浓度(40,80mg/L)Cd处理下减少.选取8条寡核苷酸引物(10bp),利用RAPD随机扩增技术,对菜豆幼苗叶片细胞基因组DNA进行扩增,8条引物均产生特异性谱带.正常叶片基因组DNA的RAPD图谱得到46条谱带.与正常组相比,Cd处理下利用不同引物扩增得到的RAPD图谱发生改变,呈现不同程度的谱带强度增强或减弱、谱带缺失或新增,与对照的RAPD图谱存在明显差异.Cd胁迫下基因组模板稳定性下降,并随Cd处理浓度的增加,稳定性下降幅度增大.利用RAPD技术获得的DNA多态性变化,可指示镉毒害生物遗传效应,并为镉污染地区蔬菜品种的选育及镉毒性的评价提供依据. 相似文献
755.
756.
N. G. Evdokimov 《Russian Journal of Ecology》2005,36(6):400-407
Long-term stationary observations (1985–2000) on a polymorphic population of the northern mole vole (Ellobius talpinus Pall.) in Kurgan oblast were performed using the mark-recapture method. Original data were obtained on the abundance and structure of this population, which comprised individuals of three color morphs: black, brown, and intermediate (bicolor). Each morph proved to have its specific features with respect to abundance, age and sex composition, migration, birthrate, mortality, and life span. In general, this polymorphism contributes to population heterogeneity and the maintenance of population homeostasis. 相似文献
757.
V. V. Tarasov 《Russian Journal of Ecology》2005,36(3):193-199
The return of willow ptarmigans to the sites in which they nested the previous year has been studied using color banding. No factors influencing the return index have been revealed, except for its dependence in males on the time when spring begins in a given year. In northernYamal, in contrast to the temperate zone, some surviving birds fail to return to their former nesting sites. Polymorphism of individuals with respect to territorial behavioral strategy is proposed for L. lagopus populations at the northern boundary of the species range.__________Translated from Ekologiya, No. 3, 2005, pp. 215–221.Original Russian Text Copyright © 2005 by Tarasov. 相似文献
758.
L. G. Tarshis 《Russian Journal of Ecology》2005,36(2):81-88
In seven higher plant species of different taxa, structural features of underground organs have been considered, and the levels of intraspecific variation in some characters of these organs have been determined. Different pathways of the structural adaptation of these species to the environment are demonstrated on the morphological and anatomical levels.Translated from Ekologiya, No. 2, 2005, pp. 97–105.Original Russian Text Copyright © 2005 by Tarshis. 相似文献
759.
Juuso Kallinen Seppo Heinonen Aarno Palotie Arto Mannermaa Markku Ryynanen 《黑龙江环境通报》2001,21(5):409-412
Approximately one in five subjects in Finland carries some gene defect associated with 30 diseases belonging to the Finnish disease heritage, and about one in 500 children born is affected. Almost all carriers, women and men, are unaware of their condition. Recent advances in molecular medicine have offered the possibility of population-based carrier screening for recessive disorders. We studied acceptance and attitudes to antenatal screening for aspartylglucosaminuria (AGU) and infantile neuronal ceroid lipofuscinosis (INCL). From January 1995 until December 1996 carrier tests were offered at Kuopio City Health Center, free of charge to all pregnant women attending maternity care units. Women found to be carriers of AGU (n=47) or INCL (n=14) underwent detailed genetic counseling, and their male partners were also offered the test. If both partners appeared to be carriers we offered prenatal testing (n=1). No affected fetuses were detected. Attitudes towards the gene test were elicited by means of a questionnaire. Altogether 87% of pregnant women elected to undertake the gene tests. Antenatal screening for gene defects was feasible and well accepted, and it provided an effective way to find carriers of genetic diseases and to incorporate prenatal testing into this process. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
760.
Gary Comstock 《Journal of Agricultural and Environmental Ethics》1990,3(2):114-146
Should we continue to support publicly funded research on genetically engineered herbicide resistant crops? In Part One, I discussed the difference between science and ethics, presented a brief history of weed control, and explained three moral principles undergirding my environmentalist perspective. I then argued that unqualified endorsement (E) of the research is unjustified, as is unqualified opposition (O). In Part Two, I argue against qualified endorsement (QE), and for qualified opposition (QO). 相似文献