南京市蛾类区系种类组成的变化及分析

通过1980~1982年和2004~2006年2次普查结果,编制出了"南京市区蛾类名录"。在对这2次采获的蛾类种类及若干主要种进行比较发现,南京市区在20 a间,其区系种类组成及若干重要经济虫种的发生、发展情况,都发生了显著变化。该文还就发生显著变化的原因进行了深入地分析。     

Evaluation of competition and light estimation indices for predicting diameter growth in mature boreal mixed forests

A series of conventional distance-independent and distance-dependent competition indices, a highly flexible distance-dependent crowding index, and two light resource estimation indices were compared to predict individual tree diameter growth of five species of mature trees from natural-origin boreal mixed forests. The crowding index was the superior index for most species and ecosites. However, distance-independent indices, such as basal area of competing trees, were also effective. Distance-dependent light estimation indices, which estimate the fraction of seasonal photosynthetically-active radiation available to each tree, ranked intermediate to low. Determining separate competition indices for each competitor species accounted for more variation than ignoring species or classifying by ecological groups. Species’ competitive ability ranked (most competitive to least): paper birch ≈ white spruce ≈> trembling aspen > lodgepole pine > balsam poplar. Stratification by ecosite further improved model performance. However, the overall impact of competition on mature trees in these forests appears to be small.     

吸附性能的研究

对糠醛渣制得的活性炭,采用S2Cl2回流负载,再微波焙烧的方法进行改性,采用Boe-hm滴定法和FT-IR分析了活性炭改性前后表面官能团的变化情况;对比了活性炭改性前后孔径分布情况;并探讨了改性活性炭对水体中的Hg2+吸附性能。Boehm滴定分析表明活性炭改性后的总酸度、羧基、内酯基皆有增加;FT-IR谱图上700～500 cm-1范围内出现了新的吸收峰说明了改性活性炭表面增加了C—S、S—S键,孔径分布分析表明改性后活性炭微孔更加发达。在Hg2+初始质量浓度1～6 mg/L、温度25℃、pH值6.0～7.0、吸附时间180 min的条件下,经S2Cl2改性后活性炭用量为2.5 g/L时,对水体中Hg2+去除率达93%以上。     

Function and value of water conservation in different age classes of Acacia mangium plantations

For this paper, we studied the water-holding capacity of canopy, vegetation layer under canopy and litter layer, the water-holding capacity and permeability of soil as well as their changes with growth of stands in Acacia mangium plantations of three different age classes (four-, seven-and 11-year-old). Results show that total water-holding above ground in the order of 11-year stand age (52.86 t/hm²)>seven-year stand age (41.90 t/hm²)>seven-year stand age (25.78 t/hm²), the increment tendency increased with stand age. Similar sequence also obtained on the water-holding capacity and permeation capacity of soil (0–40 cm). The total water-storage capacity both above ground and soil in four-year-old, seven-year-old and 11-year-old of A. mangium plantations were 2,023.0, 2,158.4 and 2,260.4 t/hm², respectively, and the all value of water conservation were 1,372.70, 1,474.42 and 1,549.91 yuan (RMB)/hm², respectively. Therefore, A. mangium plantation had a good ability to modify soil structure and good water conservation function. __________ Translated from Journal of Soil and Water Conservation, 2006, 20(5): 5–8, 27 [译自: 水土保持学报]     

超声波法活化麦草碱木素及用于PF胶黏剂的研究

麦草碱木素是我国造纸工业重要的剩余物,但是麦草碱木素的结构决定了其反应活性较低,从而使其应用受到较大的限制。笔者根据麦草碱木素的特点分别对比超声破碎仪不同的超声条件(时间:10、20、30、40min;振幅:60、80、100)和不同的溶液质量比(100:0,60:1,20:1)对麦草碱木素的活化效果,并探索用活化后的木素代替部分苯酚(10%、20%、30%、40%)制备酚醛树脂胶黏剂的可行性。研究结果表明:超声波作用可显著提高酚羟基的含量。超声波作用时间在20min、振幅80、溶液质量比20:1时效果相对较好。经过超声波活化的木素按20%的量替代苯酚制备LPF,压制的胶合板的胶合强度都达到国家Ⅰ类胶合板的要求,并能与未改性的酚醛树脂(PF)胶黏剂相媲美。     

我国木质吸音材料的发展现状分析

介绍我国主要木质吸音材料的研究与应用现状,指出存在的问题,并提出应对措施及木质吸音板今后的发展方向,以促进我国木质吸音材料产业健康发展。     

测试方法对毛竹顺纹抗剪强度的影响

以4年生毛竹为对象,分别按照国家标准、行业标准和国际标准的方法,进行顺纹抗剪强度的测试.结果表明:测试方法、试件形状以及加载速度对抗剪强度均有显著影响;行业标准的试件形状能较准确测出竹材的纯抗剪强度,综合测试时间,加载速度以0.8～1.5 mm/min为宜.     

Cytotoxic, cytoprotective and antioxidant effects of isolated phenolic compounds from fresh ginger

Twenty-nine phenolic compounds were isolated from the root bark of fresh (Yunnan) ginger and their structures fully characterized. Selected compounds were divided into structural categories and twelve compounds subjected to in-vitro assays including DPPH radical scavenging, xanthine-oxidase inhibition, monoamine oxidase inhibition, rat-brain homogenate lipid peroxidation, and rat pheochromocytoma PC12 cell and primary liver cell viability to determine their antioxidant and cytoprotective properties. Isolated compounds were also tested against nine human tumor cell lines to characterize anticancer potency. Several diarylheptanoids and epoxidic diarylheptanoids were effective DPPH radical scavengers and moderately effective at inhibiting xanthine oxidase. An enone–dione analog of 6-shogaol (compound 2) was isolated and identified to be most effective at protecting PC12 cells from H₂O₂-induced damage. Almost all tested compounds inhibited lipid peroxidation. Three compounds, 6-shogaol, 10-gingerol and an enone-diarylheptanoid analog of curcumin (compound 6) were identified to be cytotoxic in cell lines tested, with KB and HL60 cells most susceptible to 6-shogaol and the curcumin analog with IC₅₀ < 10 μM. QSAR analysis revealed cytotoxicity was related to compound lipophilicity and chemical reactivity. In conclusion, we observed distinct compounds in fresh ginger to have biological activities relevant in diseases associated with reactive oxygen species.     

浅析计算机网络与经济发展

着重论述了计算机网络与经济发展的直接关系,强调了当今世界网络效应的重要性,并提出了推动计算机发展,重视人才培养和教育的法律法规和措施.     

建筑工程项目招标投标案例解析

通过评标中遇到的一些实例,总结了典型的事件,对事件的过程结合招投标法规进行了认真解析,旨在探讨如何完善开标、评标工作,使招、投标工作能在公开、公正的前提下,实现公平竞争,为招标人选出理想的中标人,对招投标工作具有一定的借鉴作用.