长期轮作施肥对土壤有机质及其组分的影响

研究了长期轮作施肥对土壤有机质及其组分的影响，结果表明：在不施肥耕种条件下，通过粮豆轮作，基本可以维持土壤有机质的平衡，但其活性有机质含量、腐殖酸总量及胡敏酸含量却在不断下降，单施化肥，开始时土壤有机质含量降低，以后随耕种年限的延长，基本可以维持在较低水平，活性有机质、腐殖酸总量、胡敏酸和胡敏素含量降低，富里酸含量提高；施用有机肥处理，特别是施用高量有机肥，有利于提高胡敏酸和胡敏素比例，而减少富里酸的生成，培肥作用较为明显。     

试论我党对所有制结构理论的探索与创新

多年来,我党在不断深化对社会主义认识的基础上,对传统所有制结构理论进行了大胆的探索与创新,丰富和发展了马克思主义关于所有制问题的理论.党的十六大在此基础上进一步强调,要把坚持公有制的主体地位和促进非公有制经济发展统一于社会主义现代化建设的进程中.同时提出理顺收入分配关系,"完善保护私人财产的法律制度".显示了党和政府坚持现阶段"基本经济制度"这一政策的长期性、连续性和稳定性.对引导我国多种所有制经济的健康发展,必然产生深远影响.     

利用中温沥青试制浸渍剂沥青

为生产高质量电极用浸渍剂沥青，利用煤油、洗油两种溶剂按一定的比例通过沉降法来处理软沥青，使软沥青中的喹啉不溶物大大降低，生产出了高质量的浸渍剂沥青。试验表明，煤油与洗油的最佳比例为0．90：1、溶剂与软沥青的最佳比例为0．80：1。中试生产的浸渍剂沥青QI为0．1％～0．5％，质量指标接近发达国家水平，产品在生产电极浸渍试验中的应用效果良好。     

Impact of Membrane Surface Modification on the Treatment of Surface Water

New polyethersulfone (PES) based membranes for ultrafiltration (UF) were developed by blending a surface-modifying macromolecule (SMM) in the casting solution, in an attempt to minimize the impact of fouling. Fouling was evaluated using concentrated Ottawa River water (CORW), either unfractionated or fractionated via UF. These membranes also included some polyvinylpyrrolidone (PVP), a pore forming additive. A statistical analysis was conducted to evaluate the impact of some variables on the treatment of the surface water. The independent variables included PVP/PES ratio in the casting solution, with and without SMM, and the nature of the feed CORW [low molecular weight (LMW) fraction, unfractionated, high molecular weight (HMW) fraction]. The performance variables studied were total organic carbon (TOC) removal, the foulant accumulation at the membrane surface after filtration, the flux reduction, and the final permeate flux. The most important variable was the feed water. Filtration of LMW had a higher final flux, less fouling, but slightly lower TOC removal. The SMM did not significantly impact the membrane performance. TOC removal was high, compared with results reported in the literature for UF membranes.     

Staged Coagulation for Treatment of Refractory Organics

Seasonal periods of high rainfall have been shown to cause elevated natural organic matter (NOM) loadings at treatment works. These high levels lead to difficulties in removing sufficient NOM to meet trihalomethane standards, and hence better alternative treatments are required. Here the removal of NOM was investigated by conventional coagulation treatment using both bulk and fractionated NOM. Initial experiments showed that over 70% removal of the hydrophobic and hydrophilic acid fractions was achieved at the works, while only 16% of the hydrophilic nonacid fraction was being removed. Bench scale jar testing of the isolated NOM fractions demonstrated that high removals of the hydrophobic fractions were achieved and that optimized conditions increased removal of the hydrophilic fractions, indicating that staged coagulation could be of benefit in the removal of the recalcitrant fractions. Experiments using optimized staged coagulation indicated that a small increase in the removal of the total NOM of this water was possible when compared to conventional treatment.     

设施栽培条件下土壤养分及有机质组成变化趋势的研究

以黄泛平原壤质潮土不同年限的设施栽培土壤为研究对象,探讨了设施栽培条件对土壤养分及土壤有机质组成的影响。结果表明,设施栽培土壤碱解氮、速效磷、速效钾、盐分含量均明显高于大田,其含量主要取决于施用化学肥料的种类和数量,随栽培年限的增加而增加;土壤有机质、腐殖酸、胡敏酸含量随种植年限有升高趋势;HA/FA与栽培年限显著相关,表示设施栽培条件下,土壤熟化程度随有机肥料的逐年施用而有所提高,但HA/FA变化幅度不大,这可能与设施栽培形成的高温高湿条件及施用有机肥料中难分解物质的含量有关。     

昆虫病毒在害虫生物防治中的应用

利用昆虫病毒防治害虫是生物防治的一种有效方法。主要针对昆虫病毒的作用机制、后效作用以及重组昆虫病毒和昆虫病毒感染增效物质等方面进行了阐述。     

Mass spectrometry of atmospheric aerosols--recent developments and applications. Part I: Off-line mass spectrometry techniques

Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of mass spectrometry. Mass spectrometry provides high sensitivity with a fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of mass spectrometry of atmospheric aerosols. In Part I of this two-part review, we concentrate on off-line mass spectrometry techniques, which require sample collection on filters but can provide detailed molecular speciation. In particular, off-line mass spectrometry techniques utilizing tandem mass spectrometry experiments and high resolution mass analyzers provide improved insight into secondary organic aerosol formation and heterogeneous reaction pathways through detailed structural elucidation at the molecular level.     

Indoor air quality in Portuguese schools: levels and sources of pollutants

Indoor air quality (IAQ) parameters in 73 primary classrooms in Porto were examined for the purpose of assessing levels of volatile organic compounds (VOCs), aldehydes, particulate matter, ventilation rates and bioaerosols within and between schools, and potential sources. Levels of VOCs, aldehydes, PM_2.5, PM₁₀, bacteria and fungi, carbon dioxide (CO₂), carbon monoxide, temperature and relative humidity were measured indoors and outdoors and a walkthrough survey was performed concurrently. Ventilation rates were derived from CO₂ and occupancy data. Concentrations of CO₂ exceeding 1000 ppm were often encountered, indicating poor ventilation. Most VOCs had low concentrations (median of individual species <5 μg/m³) and were below the respective WHO guidelines. Concentrations of particulate matter and culturable bacteria were frequently higher than guidelines/reference values. The variability of VOCs, aldehydes, bioaerosol concentrations, and CO₂ levels between schools exceeded the variability within schools. These findings indicate that IAQ problems may persist in classrooms where pollutant sources exist and classrooms are poorly ventilated; source control strategies (related to building location, occupant behavior, maintenance/cleaning activities) are deemed to be the most reliable for the prevention of adverse health consequences in children in schools.