Cu2+对中华倒刺鲃超氧化物歧化酶活性的影响

Cu2+是养殖水体的常见污染物,为了评估Cu2+对鱼类超氧化物歧化酶(SOD)的影响,将中华倒刺鲃暴露于含0.01～0.32 mg/L Cu2+的水体中饲养8 d,测定肌肉、血浆及肝脏中SOD活性的变化.实验结果显示,低浓度Cu2+(0.01 mg/L)对肌肉、血浆及肝脏的SOD有诱导作用,随着处理时间的延长而升高.但当浓度较高(0.04mg/L以上)时,SOD活性均呈现先诱导后抑制的趋势.Cu2+浓度越高,SOD活性上升越急剧,出现活性抑制的时间就越提前.此外,SOD在3种组织中的分布亦存在明显差异,肝脏的SOD活性最大.这些结果表明,肝脏SOD活性更宜作为Cu2+污染的生物标记.     

Energy balance for ethyl alcohol production from crops

Energy requirements to produce ethyl alcohol from three different crops in Brazil (sugarcane, cassava, and sweet sorghum) were calculated. Figures are presented for the agricultural and industrial phases. The industrial phase is always more energy-intensive, consuming from 60 to 75 percent of the total energy. Sugarcane is the more efficient crop for ethyl alcohol production, followed by sweet sorghum and cassava from a net energy viewpoint. The utilization of sweet sorghum stems might increase the total energy gain from this crop to almost the same level as sugarcane. Cassava has a lower energy gain at the present state of agriculture in Brazil.     

Catalytic conversion of biomass to monofunctional hydrocarbons and targeted liquid-fuel classes

It is imperative to develop more efficient processes for conversion of biomass to liquid fuels, such that the cost of these fuels would be competitive with the cost of fuels derived from petroleum. We report a catalytic approach for the conversion of carbohydrates to specific classes of hydrocarbons for use as liquid transportation fuels, based on the integration of several flow reactors operated in a cascade mode, where the effluent from the one reactor is simply fed to the next reactor. This approach can be tuned for production of branched hydrocarbons and aromatic compounds in gasoline, or longer-chain, less highly branched hydrocarbons in diesel and jet fuels. The liquid organic effluent from the first flow reactor contains monofunctional compounds, such as alcohols, ketones, carboxylic acids, and heterocycles, that can also be used to provide reactive intermediates for fine chemicals and polymers markets.     

Coelioscopic-assisted prefemoral ovariosalpingectomy in a d`Orbigny slider (Trachemys dorbigni) using a digital otoscope

The purpose of this study was to assess the unilateral prefemoral coelioscopic-assisted approach for ovariosalpingectomy in a d`Orbigny slider (Trachemys dorbigni) using a digital otoscope. Twenty healthy turtles were randomly assigned to one of two groups, for right (GR; n=10) or left (GL; n=10) prefemoral access, for coelioscopic-assisted ovariosalpingectomy. Anesthesia and surgery times, body weight, and ovary/oviduct weight data were recorded. Anesthesia and surgery times did not differ significantly between the groups. Wound closure was the most time-consuming surgical step. Ovary and body weights significantly affected the exposure time of the ipsilateral and contralateral ovaries, respectively. Two intraoperative complications were reported. All the animals recovered uneventfully. The digital otoscope can be safely and effectively used for coelioscopic-assisted single-access, unilateral prefemoral ovariosalpingectomy in d`Orbigny slider.     

黍族植物的叶片扩张和蒸腾作用对土壤水分亏缺的响应特征

Plant processes, such as leaf expansion, stomatal conductance and transpiration, are affected by soil water, particularly in water-stressed environments. Quantifying the effects of soil water on plant processes, especially leaf expansion and transpiration, could be useful for crop modeling. In order to quantify the leaf expansion and transpiration in response to soil water deficit in three millet species, common (Panicum miliaceum L.), pearl (Pennisetum glaucum L.) and foxtail (Setaria italica L.) millets, a pot experiment was performed at the Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. The soil water status was characterized by the fraction of transpirable soil water (FTSW). Leaf area and transpiration were measured daily. Relative leaf area expansion (RL) and relative transpiration (RT) data were plotted against FTSW. Finally the FTSW thresholds for RL and RT were calculated using linear-plateau and logistic models. The results showed that the thresholds for RL and RT were 0.68 and 0.62, respectively, based on all measured data of the three millet species using the linear-plateau model, indicating that RL and RT were constant when FTSW decreased from 1 to the threshold point. Thereafter, until FTSW = 0, RL and RT declined linearly with a slope of 1.48 and 1.43, respectively. Although millet is cultivated as a resistant crop in arid, semiarid and marginal lands, it showed an early response to soil water deficit at high FTSW thresholds. As leaf expansion and transpiration can be considered morphological and physiological variables, respectively, the results in this study indicate that millet has strong morphological flexibility when faced with soil water deficit.     

西藏核桃休眠及萌芽特性研究

利用浓硫酸浸泡处理西藏核桃种子,通过种子吸水率、不同层积方法和内源抑制物对小白菜萌发影响试验等方面来研究西藏核桃的休眠及萌芽特性.结果表明:用浓硫酸处理种吸水率大于对照,种壳并不是引起休眠的主要原因,外壳、内种皮、种仁可能均含有抑制种子发芽物质.用浓硫酸浸泡90 min,变温层积萌动时间早,且萌动率高;低温层积160 d,再在22℃恒温条件下发芽率高,为68%.     

森林公园道路景观林的改造配置模式——以老山森林公园为例

道路景观林是山林景观的窗口和向导,道路景观林的建设是森林林相改造的重要内容。以南京市老山森林公园为例,探讨道路景观林建设的指导思想、原则与方法,并结合案例提出道路景观林改造模式,以实现森林公园由经济林转变为景观生态林的改造目标。     

Alkaline hydrolyzable nitrogen and properties that dictate its distribution in paddy soil profiles

Nitrogen (N) is a key nutrient for rice production, and its bioavailability in paddy soils is strongly coupled to soil organic matter (SOM) cycling. A better understanding of potentially available N forms in soil, such as alkaline hydrolyzable N (AH-N), and their depth distribution will support the development of best management practices to improve the N use efficiency of rice while minimizing adverse environmental effects. Fifteen rice (Oryza sativa L.) fields from Southern Brazil were selected, and stratified soil samples were taken to a depth of 60 cm before crop establishment. Selected soil physical and chemical properties were analyzed to evaluate their relationships with AH-N contents in the soil profile. The AH-N contents below 20 cm varied extensively (increased, reduced, or constant) compared with that above 20 cm. Although clay and clay + silt contents were highly correlated to AH-N for some soils, the major property dictating AH-N distribution by depth was total N (TN), as the correlation between TN and AH-N was mainly by direct effect. The proportion of TN recovered as AH-N across sites and depths presented high amplitude, and thus AH-N was not a constant N pool across depths, indicating that AH-N can be affected by soil management practices even when TN showed no major changes. The distinct distribution of AH-N across soil sampling sites and depths indicates that depths greater than 20 cm should be considered when calibrating the AH-N index for N fertilizer recommendations for flooded rice in Southern Brazil.     

Macrophage lysozyme stimulation by fructose-1-6-diphosphate

FDP produces an increase of serum lysozyme concentration which may be related to stimulation of the phagocytic activity. Mice macrophages in vitro produce extracellular and intracellular LSZ (lysozyme) and FDP (fructose-1-6-diphosphate) increases this production. Also in vivo FDP stimulates the macrophages intracellular lysozyme production. The toxic activity in vitro and the protection in vivo against Staphylococcus pyogenes after FDP administration can also be related to macrophage stimulation.     

乡镇企业概念动态化探究

在过去的近三十年中,乡镇企业在转移富余劳动力,发展县域经济等方面作出了卓越的贡献.但是,随其内外环境的变化,乡镇企业的发展遭到质疑,有学者认为乡镇企业的名称应改为中小企业或者是民营企业.本文通过对乡镇企业历史变迁、概念内涵变化的探究,提出乡镇企业概念内涵的界定应:扬弃约束,体现其在"三农"中的作用.