Power spectrum density and experimental modal analysis of wide belt sander applied in domestic wood industry

This paper took the upper-lower wide belt sander B229 with four-feet wide belts, manufactured in China, as the study target. By means of framework dynamic design, we study its vibration characteristics by commencing from the place having horizontal defects and used experimental modal analysis (EMA) and power spectrum density (PSD) to observe the sanding parts and the whole machine, respectively. In the modal test, we mainly adopted the cross spots testing method to get the frequency response function of the fixed spots to every excitation vibration spot, then applied the SISO frequency response function and the frequency response function fitting method to identify and complete parameter recognition, respectively. The typical frequency response function chart of the whole machine and its sanding parts, as well as its second-order mode charts of contacting roller, were obtained. Through PSD analysis, we can get the amplitude-frequency spectrum and drive frequency. Translated from Scientia Silvae Sinicae, 2005, 41(6): 132–137 [译自: 林业科学]     

辽宁省森林生长量(率)表的编制

以全省森林资源连续清查第3次和第4次复查复位样地693块、复位样木37101株为基础数据,利用计算机归类计算,编制出全省各树种(组)森林生长量(率)表。     

卷丹保健饮料的研制

根据卷丹富含淀粉、蛋白质的特点 ,以干片及制淀粉所得的清汁为原料 ,进行了保健饮料的加工工艺研究 .结果表明 :采用 0 .0 2 %的黄原胶、0 .1%的 CMC—Na和 0 .1%的海藻酸钠作为稳定剂 ,使卷丹奶有较好的稳定性 ;卷丹奶饮料最佳配方为 :1∶ 9的卷丹与水混合 ,6%的白砂糖 ,4%的脱脂乳 ,0 .1%的柠檬酸 .清汁饮料的最佳配方为 :6%的白砂糖 ,0 .1%的柠檬酸     

枣镰翅小卷蛾性诱试验

在陕北清涧县张家畔枣林内,进行枣镰翅小卷蛾性诱试验。发现该方法简便易行,准确度高,是一理想的测报手段。试验得出诱捕器布设间距以25m 为宜,悬挂高度不应低于2m,诱捕器口径以20cm 较好。第二代卵孵化盛期为8月8日至15日,此时也是进行化学农药和生物制剂防治的大好时机。     

大孔树脂ADS-7分离纯化多穗柯黄酮工艺研究

采用大孔树脂ADS-7分离纯化多穗柯黄酮粗提物(CE),对主要工艺条件进行了研究。得出最佳工艺条件为:将CE先配成10%(体积分数)CE溶液,10?溶液体积与树脂质量比值(mL∶g)略大于3、在中性pH值下静态吸附2 h,再以3倍装柱体积(1 500 mL)的80%(体积分数)乙醇、每小时1倍装柱体积流速进行动态洗脱。该工艺条件得到的纯化产物中黄酮的质量分数由粗提物中的40%提高到纯化产物的88%,得率为91%。     

TMV侵染对枯斑三生烟叶片中Ca2+分布的影响

以枯斑三生烟为材料,用细胞化学沉淀法测定了TMV侵染对烟草叶片细胞中Ca^2＋分布的影响,并探讨了Ca^2＋在植物抗病性中的作用。结果发现,枯斑三生烟健叶中的Ca^2＋主要分布于细胞间隙和液泡,接种TMV后,细胞间隙中的Ca^2＋逐渐向细胞内转移,在接种后48h,Ca^2＋主要分布于过敏性坏死细胞和近坏死区细胞,远坏死区细胞间隙缺Ca^2＋;以后由于枯斑停止发展,在接种后96h远坏死区细胞逐渐恢复钙稳态。     

迷迭香抗氧化剂和精油综合提取技术研究(Ⅲ)——超临界CO2萃取法

超临界CO2萃取(SCDE)法是迷迭香抗氧化剂和精油综合提取的有效方法之一.迷迭香抗氧化剂和精油超临界CO2萃取的优选条件为:萃取时间 4 h,夹带剂 95% 乙醇与迷迭香叶子的质量比为2∶5,萃取罐和分离器I的温度分别为50和 70 ℃,分离器II的温度为 40 ℃,萃取压力 20 MPa,分离压力为4～5 MPa.迷迭香精油的平均得率为 1.80%,迷迭香精油主要含有1,8 - 桉叶素、樟脑、α - 松油醇、龙脑、马鞭草烯酮、 4 - 松油醇、乙酸龙脑酯和芳樟醇等成分.迷迭香抗氧化剂的平均得率为 11.93%,主要含有鼠尾草酸、鼠尾草酚和迷迭香酸等活性成分,其质量分数分别为 23.61%、 7.33% 和 5.13%.     

湖南主要树种木材的化学成分分析

采用我国木材化学成分分析国家标准，对湖南４０种主要树种木材的化学成分组成进行了分析测定．并结合各树种木材的化学成分及其性质，对其在工业方面的开发利用进行了探讨．所测得的数据，可供各地开发利用各种木材作为参考．     

Nitrification and denitrification in subalpine coniferous forests of different restoration stages in western Sichuan, China

Nitrification is the biological conversion of organic or inorganic nitrogen compounds from a reduced to a more oxidized state. Denitrification is generally referred to as the microbial reduction of nitrate to nitrite and further gaseous forms of nitric oxide, nitrous oxide and molecular nitrogen. They are functionally interconnected processes in the soil nitrogen cycle that are involved in the control of long-term nitrogen losses in ecosystems through nitrate leaching and gaseous N losses. In order to better understand how nitrification and denitrification change during the process of ecosystem restoration and how they are affected by various controlling factors, gross nitrification rates and denitrification rates were determined using the barometric process separation (BaPS) technique in subalpine coniferous forests of different restoration stages. The results showed that forest restoration stage had no significant effects on gross nitrification rates or denitrification rates (One-way ANOVA (analysis of variance), p < 0.05). There was no significant difference in the temperature coefficient (Q ₁₀) for gross nitrification rate among all the forest sites (One-way ANOVA, p < 0.05). Gross nitrification rates were positively correlated with water content (p < 0.05), but not with soil pH, organic matter, total nitrogen, or C/N ratios. Denitrification rates in all the forest soils were low and not closely correlated with water content, soil pH, organic matter, or total nitrogen. Nevertheless, we found that C/N ratios obviously affected denitrification rates (p < 0.05). Results from this research suggest that gross nitrification is more responsible for the nitrogen loss from soils compared with denitrification. Translated from Journal of Plant Ecology, 2006, 30(1): 90–96 [译自: 植物生态学报]