黄土高原径流侵蚀功率输沙模型的改进

水土流失对流域生态危害严重,输沙量模拟和预测可以为流域水土流失防治提供依据,因此精确的输沙模型是流域水土流失治理的重要工具。为了精确模拟变化环境下黄土高原年输沙量,该研究基于黄土高原19个水文站的径流和输沙数据,通过随机森林变量重要性度量方法评估年径流侵蚀功率、淤地坝指数、淤地坝相对指数、归一化植被指数、不透水地面积等因子对流域年输沙量的影响,使用非线性最小二乘法估算年输沙模型参数,对比分析不同因子组合的年输沙模型精度,提出适用性较强的黄土高原年输沙模型,据此开展年输沙量变化贡献率分析。结果表明：1）以幂函数形式构建的仅含径流侵蚀功率单因子输沙模型精度与流域面积有显著的负相关关系,相关系数为-0.505（P<0.05）,模型精度随着流域面积增大而下降,在大于7 000 km2的流域适用性较差;2）年径流侵蚀功率、淤地坝指数及不透水地面积因子组合建立的多因子年输沙模型在黄土高原适用性最佳,模型在率定期NSE平均值为0.84,RMSE平均值为0.21亿t,在验证期纳什系数平均值为0.79,均方根误差平均值为0.27亿t。3）影响研究流域年输沙量变化的因素依次是：年径流侵蚀功率、不透水地面积和淤地坝指数。研究可以为黄土高原不同区域水土流失防治和生态治理工作提供理论支撑。     

城市开敞空间在绿地规划中的作用和意义--以《包头市绿地系统规划》为例

城市开敞空间的主要存在形式是城市绿地,城市绿地在改善城市环境质量、维持城市生态平衡方面起着巨大的作用;在阐明城市绿地重要性的同时,从绿地的结构、布局出发,以创建生态城市为目标,尝试性的提出实现这一目标的原则。     

Status of urban vegetation in Guangzhou City

According to a survey for the urban vegetation of Guangzhou, urban vegetation has a significantly difference from natural vegetation because of intense human impacts. The research was conducted in a synthetic survey for soil, species diversity, roadside trees and ecological function of urban vegetation in Guangzhou City. The results showed that: (1) soil densities of urban roadside and park forests were higher than mean density of natural forest soil. The pH values of soil in urban roadside were higher too, and the content of organic matter and the concentration of nitrogen were lower. (2) Species diversity of urban vegetation was lower. The most number of species was only 16 species in tree layers of urban forest. (3) Tree growth was limited by narrow space in high-density urban area, where the trees with defects and disorders were common. (4) Comparing with mature natural forests, the productivity of urban vegetation was lower. The effect of urban vegetation on balance of carbon and oxygen were influenced by the low primary production of urban vegetation. Therefore, the growth condition for urban vegetation should be improved. Biodiversity, primary production and ecological function should be increased for urban vecletation in order to improve urban eco-environment.     

观光桃园昆虫群落结构与优势种生态位

系统调查观光桃园昆虫群落结构及其优势种的时空生态位并进行测定.结果表明:昆虫群落结构丰富,桃园有昆虫9目25科34种,桃蛀果蛾、梨小食心虫、桃蛀野螟、桃潜蛾、桑白盾蚧、桃蚜、小花蝽、异色瓢虫、黑带食蚜蝇、叶色草蛉、黑缘红瓢虫等是桃园昆虫的优势种.昆虫群落物种数、个体数、多样性指数、均匀度指数随时间变化而波动.生态位宽度在害虫亚群落中为:桑白盾蚧>桃蚜>桃潜蛾>梨小食心虫>桃蛀野螟>桃蛀果蛾,天敌亚群落中为:黑缘红瓢虫>异色瓢虫>黑带食蚜蝇>叶色草蛉>小花蝽.黑缘红瓢虫与害虫的生态位重叠值均较大,而且与桑白盾蚧在时间上的同步性和空间上的同域性均优于其他天敌,是桃园天敌的优势种群.     

六盘山叠叠沟小流域土壤稳渗速率及其影响因子

采用小区漫流法研究叠叠沟小流域内4种典型植被下的土壤稳渗速率及其影响因子.结果表明:不同植被类型的土壤稳渗速率平均值表现为天然草地>虎榛子灌丛>沙棘灌丛>华北落叶松林地.坡向影响土壤稳渗速率表现为阴坡>半阴坡>阳坡,坡位对土壤稳渗速率的影响表现为中坡位>下坡位>上坡位,坡度对土壤稳渗速率的影响表现为中坡>陡坡>缓坡,当坡度小于25.时土壤稳渗速率随坡度增大而增大,当坡度大于25°时土壤稳渗速率随坡度增大而减小.因此,以坡度25°为分界点,找到了影响土壤稳渗速率的主导因子,并经多元逐步回归得到土壤稳渗速率与主要影响因素的分段函数.     

A promising alternate lipase for biodiesel fuel production

By screening samples from different sources, a high-yield yet low-cost lipase of Enterobacter aerogenes was found and used in biodiesel production. The enzyme activity of Enterobacter aerogenes reached 34.16 U·mL⁻¹ under the optimum conditions of initial pH 9.0, agitating at 30°C for 40 h, using NaHCO₃ and glucose as carbon sources and peptone as nitrogen source, with 0.1% (w/v) MgSO₄·7H₂O. When adding 1.0% (w/v) olive oil to the culture, the enzyme activity reached 66.31 U·mL⁻¹, which increased by 56.5% compared to that obtained by using 2.0% (w/v) olive oil as the sole carbon source. The lipase of Enterobacter aerogenes was immobilized by diatomite and used to catalyze biodiesel with rapeseed oil as raw materials, the transesterification rate was 92.91% under the optimum reaction conditions, which were using 1000 U immobilized lipase and 5 mL n-hexane, with ethanol as acyl acceptors, at the molar ratio of oil/ethanol of 1:4, and adding ethanol twice, at 35°C for 48 h. Therefore, the Enterobacter aerogenes will potentially serve as a promising alternative lipase for biodiesel production.     

蒌蒿的生物学特性及栽培中的几个问题

阐述了蒌蒿的起源分布和生物学特性，研究了其分类地位；介绍了蒌蒿地膜轻松浮面覆盖栽培形式，并从提高产量和品质的角度提出了激素使用、病虫害防治、采后处理等关键技术。     

油菜产品综合利用的研究——Ⅰ.双低油菜湘油11号菜籽饼饲养黑白花奶牛的试验

双低油菜湘油11号菜籽饼的适口性好、营养价值高,不经去毒处理,直接加入配合饲料中饲喂黑白花奶牛(怀孕、产奶),可代替75%的豆饼,本试验最高用量组每天0.95 kg/头,占日粮13.57%,饲喂双低油菜耔饼的3组牛与不用该菜籽饼的2组牛比较,挤奶量、乳脂率无显著差异;全血、血清检验均处于生物化学指标范圈;对黑白花奶牛整个繁殖周期也无影响。     

天然色素—花青甙对大白鼠的长期毒性试验

观察和测定天然色素花青甙(Antho sianine)对实验动物大白鼠的长期毒性,采取连续给药(120d),观察大白鼠的行为、体重、体温以及生理、生化指标的变化;观察对大白鼠的组织器官肉眼及组织学变化;观察花青甙对动物的安全性及可能产生的毒性和不良反应,探索该天然色素花青甙的正常用量(人每日用纯品36mg/55kg体重)以及正常人量的20倍和40倍量对大白鼠的影响,测定各组织大白鼠血液生理指标、清转氨酶及肝功能和血清尿素氮含量,检验主要脏器的肉眼变化和组织学变化。通过LD_(50)的测定(LD_(50)为11564.3173mg/kg体重)以及上述指标的测定,对天然色素花青甙的安全性和可用性给予客观的评价。为其作为食品添加色素提供科学依据。