中国北方牧区草原牧业生态经济学透视

本文采用生态经济学的理论和方法 ,揭示了中国北方牧区草原雪灾背后的生态经济问题 ,中国北方草原牧业生态经济系统的主要特点是结构脆弱 ,功能低下。随着人口的高速增长 ,经济系统对生态系统的干预大大超过生态系统的自我调节能力 ,不合理的人类经济活动破坏了生态经济平衡 ,使草原生态系统严重退化 ,牧业经济系统陷于困境 ,系统抗灾能力降低。在缺乏有效生态经济管理的情况下 ,生态效益的外部性将不可避免地使生态经济系统矛盾更加尖锐化 ,系统运行陷入双轨恶性循环 ,并最终阻碍牧业经济持续发展     

工厂化生产胡瓜钝绥螨防治柑橘全爪螨的应用效果

经过多年探索,研制成功捕食螨胡瓜钝绥螨的人工饲料配方及其大量繁殖方法,建立起年生产能力110亿～120亿头捕食螨的工厂化生产基地,生产成本降至3元/万头。1998年应用于脐橙园防治全爪螨,释放捕食螨后30～120d,防效近100%。2000年应用于芦柑园、蜜柚园防治全爪螨,释放后80～90d,防效分别达93.8%、98.1%。1a释放2次,控制期可达6个月。     

Untersuchungen zur Charakterisierung des pflanzenverfügbaren Phosphats in Thüringer Carbonatböden

Investigations on the characterization of plant available phosphate in Thuringian calcareous soils Phosphate availability in Thuringian calcareous soils and its characterization by CAL‒, NaHCO₃-, H₂O- and CaCl₂-soil tests was investigated in laboratory and pot experiments. Soil CaCO₃ contents > 10% increase the pH value of CAL solution and thus decrease phosphate extractability. The increase of pH also causes an inadequate assessment of plant available phosphate by H₂O- and CaCl₂-soil tests. The CAL soluble P content of the soil corrected by the pH value of the extraction solution was most suitable for the forecast of P uptake of corn in a pot trial. From both parameters P availability indices for calcareous soils can be calculated which are comparable with those in soils containing < 5% CaCO₃. The equation, which still has to be verified in field experiments, reads as CAL-P_corrected = CAL-P_measured · (1 + 0.83·〈pH-value_{CAL solution} — 4.1〉).     

溴虫腈的光催化降解研究

研究了溴虫腈光催化降解的过程,结果表明光催化降解速率大于光降解速率,且分别遵循动力学一级方程式C1=10.325e^-0.1635t,Ct=10.202e^-0.0069t,采用正交试验分析了各因素对溴虫腈光催化降解影响的顺序：纳米TiO2浓度＞溴虫腈初始质量浓度＞pH＞温度,其中纳米TiO2浓度影响特别显著,并确定了优化降解反应条件.     

旋装式柴油滤清器外泄漏分析

介绍了旋装式柴油滤清器几个关键的外泄漏点,分析其各自特点和成因,并从设计和生产工艺的角度上加以分析,探讨其解决方案和控制方法。     

Climate change and soil erosion on agricultural land in england and wales

To assess the effects of climate change on soil erosion we need to model changes in rate, frequency and extent of erosion. Present day rates of soil erosion for agricultural land in England and Wales are known from a national monitoring scheme and also from a local one. The latter, for the South Downs, covers a seven-year period and includes climatic data. This shows a strong correlation between total erosion and a Rainfall Index. The availability of these databases allows us to use existing models such as EPIC and an Expert System to predict erosion rates for postulated warmer and wetter (winter) conditions. EPIC is particularly suitable for specific sites where detailed data exists and crop yield implications can also be modelled. A rule-based Expert System approach allows us to examine erosion rates at a different scale across the landscape. We postulate that water erosion rates on arable land in the lowlands will increase markedly in severity, frequency and extent especially if land use changes. In the uplands predicted climatic warming suggests a longer growing season and fewer frosts: these may lead to a decrease in erosion of overgrazed eroding slopes. Increases in erosion rates are not inevitable if policy decisions are taken and implemented in good time.     

俄罗斯进口禁令对中国柑橘出口的影响

俄罗斯是中国第二大柑橘出口市场,我国柑橘对俄罗斯市场的依赖程度较强。因此,俄罗斯对我国柑橘进口禁令的颁布,会对我国柑橘出口造成较大影响,其中最严重的是宽皮柑橘和葡萄柚及柚的出口。所以,我国一方面需要加大科技投入力度,构建绿色安全的生产模式,提高柑橘产品质量。另一方面需要强化出口市场的目标导向性,加快建设柑橘出口基地,增强应对技术性贸易措施的能力。最后还需要积极开拓新的柑橘市场。     

响叶杨良种繁育研究进展

响叶杨是我国特有的速生阔叶用材树种。本文就响叶杨的优树选择、无性繁殖、杂交育种等方面的研究进展进行了比较全面的回顾,并指出了响叶杨以往研究所存在的不足,探讨了今后响叶杨遗传改良研究应着重解决的一些问题。     

地膜覆盖灌水技术在北方地区的应用

地膜覆盖可有效改善作物根部生态环境、减少地面糙率和地面蒸发。根据我国不同地区降雨、蒸发和作物种植等条件,提出长城风沙线以北高蒸发、少雨区,较为适宜的灌水方法有膜下滴灌技术、平膜覆盖膜孔灌水技术等;长城风沙线以南小麦适生区为中等降雨和蒸发强度地区,条播作物适宜的地膜灌水方法有垄膜覆盖膜缝灌水和膜孔灌水、平膜覆盖膜孔灌水等。