高职计算机实验教学改革探索

为增强高职学生的实践能力和就业竞争力,针对高职计算机实验教学存在的教学效率偏低、教学方法单一、学生主体地位不突出等问题,给出具体改革措施,包括充分利用网络资源、加强实验教师队伍建设、创新实验内容和方法等.     

Respiration as the main determinant of carbon balance in European forests

Carbon exchange between the terrestrial biosphere and the atmosphere is one of the key processes that need to be assessed in the context of the Kyoto Protocol. Several studies suggest that the terrestrial biosphere is gaining carbon, but these estimates are obtained primarily by indirect methods, and the factors that control terrestrial carbon exchange, its magnitude and primary locations, are under debate. Here we present data of net ecosystem carbon exchange, collected between 1996 and 1998 from 15 European forests, which confirm that many European forest ecosystems act as carbon sinks. The annual carbon balances range from an uptake of 6.6 tonnes of carbon per hectare per year to a release of nearly 1 t C ha(-1) yr(-1), with a large variability between forests. The data show a significant increase of carbon uptake with decreasing latitude, whereas the gross primary production seems to be largely independent of latitude. Our observations indicate that, in general, ecosystem respiration determines net ecosystem carbon exchange. Also, for an accurate assessment of the carbon balance in a particular forest ecosystem, remote sensing of the normalized difference vegetation index or estimates based on forest inventories may not be sufficient.     

进水碳磷比对连续流反硝化除磷工艺脱氮除磷效果的影响

针对连续流双污泥反硝化除磷工艺,考察进水碳磷质量比(m(C)/m(P))对化学需氧量(COD)、氨氮和总磷(TP)去除效果的影响.系统进水COD和氨氮分别保持在250和45 mg/L左右,通过改变进水TP浓度来调整m(C)/m(P).实验结果表明:在m(C)/m(P)比分别为64.1,42.0,33.0和17.8的情况下,TP去除率分别为93.2％,92.0％,78.3％和65.8％,除磷效率明显降低.在m(C)/m(P)＞42.0的情况下,出水TP低于0.5 mg/L.随着m(C)/m(P)的降低,反硝化聚磷污泥释磷量和净聚磷量增加,净聚磷量分别为3.63,5.33,6.26和10.3mg/L.m(C)/m(P)减小有利于提高生物除磷系统的稳定性,但出水磷浓度会有所增加,可通过适当延长后置曝气池停留时间来降低出水磷浓度.m(C)/m(P)对COD的去除和脱氮的效果影响不大,COD去除率保持在85.6％～93.1％,氨氮的去除率大于93％.     

Functional cartography of complex metabolic networks

High-throughput techniques are leading to an explosive growth in the size of biological databases and creating the opportunity to revolutionize our understanding of life and disease. Interpretation of these data remains, however, a major scientific challenge. Here, we propose a methodology that enables us to extract and display information contained in complex networks. Specifically, we demonstrate that we can find functional modules in complex networks, and classify nodes into universal roles according to their pattern of intra- and inter-module connections. The method thus yields a 'cartographic representation' of complex networks. Metabolic networks are among the most challenging biological networks and, arguably, the ones with most potential for immediate applicability. We use our method to analyse the metabolic networks of twelve organisms from three different superkingdoms. We find that, typically, 80% of the nodes are only connected to other nodes within their respective modules, and that nodes with different roles are affected by different evolutionary constraints and pressures. Remarkably, we find that metabolites that participate in only a few reactions but that connect different modules are more conserved than hubs whose links are mostly within a single module.     

鱼尼丁受体类杀虫剂的研究进展

介绍了鱼尼丁受体类新型杀虫剂的创制现状、作用机制、生物活性、毒性及合成方法,由于此类杀虫剂的结构独特、作用方式新颖、对鳞翅目害虫效果好、杀虫广谱,该类药剂对各种益虫和天敌安全,对现用的杀虫剂无交互抗性,具有良好的发展前景.     

输电线路综合电流差动保护方案的研究

根据实现差动保护功能所需信息类型的不同，提出分相电流差动和综合电流差动的新分类方法，并列举已有的综合电流差动保护方案．在对已有方案的性能评估和分析基础上，给出负序电流与正序电流故障分量相配合的综合电流差动新原理．理论分析和EMTP仿真表明，该方案可以对各种类型的区内故障灵敏动作．     

The DNA sequence and analysis of human chromosome 13

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.     

Catastrophic shifts in ecosystems

All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.     

甘氨酸在电沉积铁铬合金中的作用

研究不同浓度甘氨酸对电沉积铁铬合金过程的影响,分析了甘氨酸在电沉积过程中的作用.加入甘氨酸后,可得到优良的镀层,而不含甘氨酸时,镀层中夹杂铬的化合物,造成镀层质量低劣.甘氨酸浓度为0.4～0.8 mol·L-1时,镀层中铬含量较稳定.甘氨酸的加入使得阴极极化增加,电位负移.在此镀液中,甘氨酸与Fe(Ⅱ)络合,使其析出电位负移,达到铁铬共沉积的目的.