通用小型汽油机尾气排放NO的净化

采用Pt-Rh催化器净化方法,并着重探讨了以降低NO排放为主的Pt-Rh催化器性能、排放温度、NO还原催化的性能和转化效率控制等问题。试验研究了Pt-Rh催化器的转化效果、其间的相互影响和作用,并提出相应的排放建议。结果表明:当贵金属Rh的加入量为30g时,Pt-Rh催化器可有效降低小型汽油机的NO排放量,最高转化效率达到48%,同时对HC、CO的排放也有一定的降解作用。     

退耕还林模式板栗林下多样性及生物量研究

[目的]为桂西北地区石漠化治理、植被恢复以及促进地方经济发展提供科学依据。[方法]采用典型样地法对广西东兰县退耕还林模式板栗林下多样性及生物量进行研究,并以未退耕地(玉米地)作为对照。[结果]板栗林下灌木层的丰富度指数为0.283 2~0.431 4,Simpson多样性指数为0.675 1~0.838 9,Shannon-Wiener多样性指数为2.042 0~2.771 2;草本层的Simpson多样性指数为0.624 5~0.737 8,Shannon-Wiener多样性指数为1.715 2~2.471 5。未退耕地(玉米地)灌木层的丰富度指数为0.202 3~0.226 1,Simpson多样性指数为0.543 3~0.572 8,Shannon-Wiener多样性指数为1.289 6~1.318 8;草本层的Simpson多样性指数为0.382 3~0.436 9,Shannon-Wiener多样性指数为1.106 0~1.164 1。板栗林下生物量随着退耕年限的增长呈现出上升的趋势,且灌草地上部分的生物量均大于地下部分。经方差分析可得,6~9年生板栗林下灌草多样性和总生物量具有显著差异,未退耕地(玉米地)灌草植被多样性和总生物量无显著差异。[结论]退耕还林对板栗林下植被的恢复具有很好的促进作用,有必要加大退耕还林力度。     

退耕还林中林草模式效益评价与物种的选择与配置

在退耕还林工程的实施过程中，科学合理地选择退耕还林模式、有效地利用坡耕地资源，对山区生态状况的改善和社会经济的可持续发展具有积极作用。文章通过对林草模式效益的评价以及对目前林草模式中存在的问题进行分析，从而探讨林草模式下林草长期共存的生态经济链发展方向、树种(竹)与草种选择和配置模式。     

Estimation of the fine root biomass in a Japanese cedar (Cryptomeria japonica) plantation using minirhizotrons

We estimated fine root biomass in a Japanese cedar (Cryptomeria japonica) plantation using a min-irhizotron technique. Since data obtained from minirhizo-trons are limited to the length and diameter of fine roots observed on minirhizotron tubes, data conversion is necessary to determine the fine root biomass per unit soil volume or unit stand area. We first examined the regression between diameter squared and weight per unit length of fine roots in soil core samples, and calculated the fine root biomass on minirhizotron tubes from their length and diameter. Then we determined conversion factors based on the ratio of the fine root biomass in soil core samples to that on minirhizotron tubes. We examined calculation methods, using a single conversion factor for total fine root biomass in the soil for depths of 0–40cm (Cal1), or using four conversion factors for fine roots in the soil at 10-cm intervals (Cal2). Cal1 overestimated fine root biomass in the lower soil or underestimated that in the upper soil, while fine root biomass calculated using Cal2 better matched that in soil core samples. These results suggest that minirhizotron data should be converted separately for different soil depths to better estimate fine root biomass.     

延安市退耕还林工程林种、树种组成分析研究

林种结构和树种组成是退耕还林工程的关键问题之一,本文分析了延安市退耕还林工程实施以来造林林种和树种组成,指出其存在林种选择上经济林面积过小,使退耕农户从退耕地中收益减少;树种单一,纯林面积过大等问题。建议要因地制宜地发展经济林,适地适树,乔灌草结合,多营造混合林。     

Direct estimation of carbon mass of organic layer from dry weight

The organic layer is an important carbon pool in the forest ecosystem but has sometimes been underestimated or ignored. An equation estimating the carbon mass of the organic layer from its dry weight was developed using a dataset collected from various forests in Japan. The equation (logC = –0.393 + 1.031logW, where C is the carbon mass of the organic layer per unit area and W is the dry weight of organic layer per unit area) could be used to estimate the carbon mass of the organic layer with a small error (R ² = 0.986, n = 67). The factor that converts organic matter to carbon was also examined. The factor of 1.89 ± 0.23 was suitable for the organic layer.     

Chemical conversions of salvianolic acid B by decoction in aqueous solution

Salvianolic acid B (Sal B) is the most abundant phenolic compound in Salvia miltiorrhiza, which has been widely used for the treatment of cardiovascular diseases in Oriental medicine. To elucidate structure of the converted compounds of Sal B by decoction in aqueous solution, Sal B (200mg) was decocted in an aqueous solution (200mL) at pH 4.9 and the decocted solution was purified by Sephadex LH-20 column chromatography and preparative HPLC. The 13 converted compounds were isolated and the chemical structures were determined by NMR and MS. In addition to the 4 compounds previously reported as conversion products of Sal B by decoction, 9 compounds were first reported with the complete structure of compounds isolated from decocted Sal B solution and three of the compounds were determined to be novel compounds. In addition, a conversion mechanism of compounds converted by decoction was proposed on the basis of kinetics studies, which reasonably supported the conversion mechanism of Sal B. The 13 compounds seemed to be produced by the hydrolysis of an ester bond, decarboxylation, retro oxa-Michael reaction, hydration, and radical reaction during decoction in aqueous solution.     

不同碳源对平菇生物学转化率的影响

[目的]研究玉米芯、稻草、棉籽壳、木屑对平菇(Pleurotus ostreatus)生物学转化率的影响,为提高栽培原料的生物学转化率和寻找新的栽培原料提供参考。[方法]试验共设4个处理,每个处理4袋,3次重复。培养料用装袋机分装到长35 cm、宽20 cm、厚0.03 mm的高密度聚乙烯塑料袋中,常压灭菌。灭菌后料袋趁热放入接种室冷却到25℃左右时接种。接种后搬入培养室内22～26℃避光培养。当菌丝长满菌袋,菌袋表面菌丝开始分泌黄水,出现小的原基后,把菌袋搬进菇房进行出菇管理。接种后观察菌种块萌发吃料情况、菌丝长势、长满菌袋的时间,另观察记录子实体分化情况、形态特征及子实体产量,计算各处理的生物学转化率,生物学转化率=鲜菇重∕培养料干重×100%。[结果]玉米芯、稻草、棉籽壳、木屑为碳源的平菇生物学转化率分别为152.19%、59.30%、166.38%、62.28%,表明不同碳源对平菇生物学转化率有较大差异。[结论]棉籽壳的生物学转化率最高,玉米芯次之,木屑和稻草最差。     

培育肉用南阳牛有关问题的商榷

作者针对传统上向役用方向进行选择的我国体大力强、肉质细致、育肥潜力较大的优良地方品种——南阳黄牛,具有后躯欠丰满、成熟晚、泌乳量低、生长较慢等缺点,利用当前南阳黄牛场规模较大,条件较好的条件,通过引血杂交改良,扩大杂种头数,加强选育,最后选出理想型杂种公母牛进行自群繁育,培育成拥有2万头数量的南阳肉牛新品种。