排序方式: 共有94条查询结果,搜索用时 15 毫秒
31.
32.
Maternal blood-cord samples from 171 women of middle socio-economic status who had been administered at least two doses of tetanus toxoid (TT), were assayed for tetanus antitoxins by passive haemagglutination (PHA) test. All the mother as well as cord samples had antitoxin titres > or = 0.015IU/ml, the generally accepted minimal protective level; 98 per cent of the mothers and 97 per cent of the newborns had levels > or = 0.125IU/ml. Transplacental dilution was observed in 45 per cent of the samples; the cord/maternal antitoxin ratio (C/M) of geometric mean titre (GMT) was found to be 0.72. The C/M ratio was not affected by the maternal age, parity, birth weight, and number of TT doses administered to mother. The study showed that tetanus antitoxins were diluted on the fetal side of circulation, but the protective levels of antitoxins were achieved in all the newborns as the mothers had received at least two doses of TT before delivery. 相似文献
33.
34.
35.
36.
The genomic organization of the hsp83 gene of Drosophila auraria, a far-eastern endemic species belonging to the montium subgroup of the melanogaster species group, is presented here. Based on in situ hybridization on polytene chromosomes, cDNA and genomic clone mapping, nucleotide sequencing, and genomic Southern analysis, hsp83 is shown to be present as a single-copy gene at locus 64B on the 3L chromosome arm in D. auraria. This gene is organized into two exons separated by a 929-bp intron. The first exon represents the mRNA leader sequence and is not translated, while the coding region, having a length of 2,151 bp, is solely included in the second exon. Nucleotide sequence comparisons of D. auraria hsp83 with homologous sequences from other organisms show high conservation of the coding region (88-92% identity) in the genus Drosophila, in addition to the conserved genomic organization of two-exons-one-intron, of comparable size and arrangement. A phylogenetic tree based on the protein sequences of homologous genes from representative organisms is in accord with the accredited phylogenetic position of D. auraria. In the hsp83 gene region, a second case of long antiparallel coupled open reading frames (LAC ORFs) for this species was found. The antiparallel to the hsp83 gene ORF is 1,554 bases long, while the two ORFs overlap has a size of 1,548 bp. The anti-hsp83 ORF does not show significant homology to any known gene sequences. In addition, no similar LAC ORF structures were found in homologous gene regions of other organisms. 相似文献
37.
In this paper we quantitatively model degree of automation (DofA) in supervisory control as a function of the number and nature of tasks to be performed by the operator and automation. This model uses a task weighting scheme in which weighting factors are obtained from task demand load, task mental load, and task effect on system performance. The computation of DofA is demonstrated using an experimental system. Based on controlled experiments using operators, analyses of the task effect on system performance, the prediction and assessment of task demand load, and the prediction of mental load were performed. Each experiment had a different DofA. The effect of a change in DofA on system performance and mental load was investigated. It was found that system performance became less sensitive to changes in DofA at higher levels of DofA. The experimental data showed that when the operator controlled a partly automated system, perceived mental load could be predicted from the task mental load for each task component, as calculated by analyzing a situation in which all tasks were manually controlled. Actual or potential applications of this research include a methodology to balance and optimize the automation of complex industrial systems. 相似文献
38.
39.
40.
ZG Zhang L Wang H Liu ZG Cao XZ Han LH Zhao ZJ Luo 《Canadian Metallurgical Quarterly》1993,18(1):16-9, 61-2
Effects of basal culture medium, sucrose concentration, natural extracts and phytohormones on protocorm differentiation were studied. The suitable medium for protocorm differentiation has been found to be 1/2Ms basal medium plus 2% w/v sucrose, 2mg/L BA, 0.2mg/L NAA and 20% (w/v) potato extract. 相似文献