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811.
探讨了博罗县下村农场坡地赤红壤的结构特征及其生产意义。结果表明,下村农场坡地赤红壤的质地较粗,土壤的团聚体含量较高,土壤的孔隙性较差;土壤粘粒、有机质,尤其是后者对土壤结构状况影响很大,土壤结构系数与土壤粘粒含量呈显著正相关,土壤1—0.05mm粗微团聚体含量、10—0.25mm水稳性团聚体及其几何平均直径值,均与土壤有机质含量呈显著正相关。坡地土壤的开发利用,应注意防治水土流失,减少团聚体的破坏,并特别注重提高土壤有机质含量,以改善土壤结构状况。  相似文献   
812.
Summary. Sensitivities to methyl eugenol of three sibling species in the Bactrocera dorsalis complex were compared. The degree of species sensitivity to methyl eugenol, i.e. B. dorsalis > B. papayae > B. carambolae (in decreasing order), was concomitant with the species age-related response to methyl eugenol as previously reported. The ability to consume methyl eugenol by the three sibling species showed similar trend - the average ME consumption per male was 0.70 ml for B. dorsalis, 0.58 ml B. papayae and 0.18 μl B. carambolae. Results obtained were discussed in relation to area-wide control of fruit fly. Received 21 April 2002; accepted 9 July 2002  相似文献   
813.
Summary Males of a natural population of Antechinus stuartii (Marsupialia) were injected at the beginning of their short, synchronous breeding period with one of twelve gamma-emitting nuclides which are individually recognizable by their unique spectial properties. This label passed to the females during ejaculation and was identified when the females were captured and counted in a whole-body counter. This technique established mating success of males and provided an estimate of reproductive success.  相似文献   
814.
Rodents cause significant damage to lowland irrigated rice crops in the Red River Delta of Vietnam. A four-year study was conducted in 1999-2002 to examine the effectiveness of applying rodent control practices using the principles of ecologically based pest management. Four 100-150 ha study sites adjacent to villages were selected and farmers on two treated sites were asked to follow a set of rodent management practices, while farmers on the untreated sites were asked not to change their typical practices. Farmers on the treated sites were encouraged to use trap-barrier systems (TBS's; 0.065-ha early planted crop surrounded by a plastic fence with multiple capture traps; one TBS for every 10-15 ha), to work together over large areas by destroying burrows in refuge habitats soon after planting (before the rats reestablish in the fields and before the onset of breeding), synchronizing planting and harvesting of the their rice crops, cleaning up weeds and piles of straw, and keeping bund (embankment) size small (<30 cm) to prevent burrowing. A 75% reduction in the use of rodenticides and plastic barrier fences (without traps or an early crop) was achieved on treated sites. The abundance of rodents was low after implementation of the management practices across all sites. There was no evidence for an effect of treatment on the abundance of rodents captured each month using live-capture traps, and no difference in damage between treatments or in yields obtained from the rice crops. Therefore, ecologically based rodent management was equally effective as typical practices for rodent management. Farmers on the treated sites spent considerably less money applying rodent control practices, which was reflected in the comparative increase in the partial benefit:cost of applying ecologically based rodent management from 3:1 on treated sites and untreated sites prior to the implementation of treatments to 17:1 on treated sites in the final year of the project.  相似文献   
815.
本文结合实例介绍了大气颗粒物来源解析最常用的模型-化学质量平衡(CMB)的原理、有效方差最小二乘解法及诊断检验技术,并用MPIN矩阵检验了拟合元素对拟合源的灵敏度,奇异值分解法(SVD)鉴别了共线源,得出天津市经济技术开发区(TEDA)的TSP主要来源为风沙、扬尘,其次为燃煤飞灰和木灰。  相似文献   
816.
本文指出了现行银行存款余额调节表编制方法存在的问题,明确提出了银行存款余额调节表的编制方法的理论依据,建立了完整的银行存款余额调节表的编制方法体系。  相似文献   
817.
In late August 1994, an outbreak of human pneumonic/bubonic plague was reported in Surat, India. During the epidemic, large amounts of pesticides, such as benzene-hexachloride (BHC) and other organochlorinated compounds were used to control the vector that might have transmitted the plague. In order to evaluate the extent of contamination, both environmental samples (9 water samples and 4 soil samples) and biological samples (5 blood and urine samples) were collected and analyzed for organochlorine residues. Samples were analyzed after hexane extraction by gas chromatography equipped with electron capture detector (GC-ECD), using a PTE-5 capillary column. The results showed that the levels of 1,1-(2,2-dichloroethenylidene)-bis[4-chlorobenzene] (DDE), a major metabolite of DDT, were low in environmental samples (water, soil), while BHC levels were relatively high in one of the water sample as well as two soil samples. The BHC and DDE levels in the biological samples were not higher than those reported earlier from India, except for serum DDE. Further studies are needed to evaluate the effect of long-term exposure as the present study was based on limited samples.  相似文献   
818.
复合表面活性剂对燃煤陶瓷窑炉黑烟润湿作用的研究   总被引:1,自引:0,他引:1  
为了有效控制燃煤陶瓷窑炉黑烟的污染,根据理论和实验研究的结果,选择合适的润湿剂和助剂,研究了阴离子表面活性剂Y1、非离子表面活性剂F1与无机盐Z1复配后溶液表面张力的变化,筛选出了表面张力较小的配比。利用所选配比对燃煤陶瓷窑炉黑烟的润湿作用进行了Walker实验研究和理论分析。实验结果表明,0.5mmol/L Y1+50mmol/L Z1+0.03mmol/L F1的配比对黑烟的润湿作用较好。并对其润湿机理进行了探讨。  相似文献   
819.
浙江省生物多样性保护对策研究   总被引:5,自引:0,他引:5  
由于森林的破坏与片段化、湖泊面积缩小、水域污染、滩涂湿地围垦和物种资源过度开发利用等原因,使生物多样性严重受协。在对浙江省生物多样性保护进行系统研究的基础上,提出了浙江省生物多样性保护的目标和主要对策。  相似文献   
820.
目前 ,含油污水的处理多以回注地下作为处理目标。然而随着油田产生的含油污水日益增多 ,仅回注地下已不能满足生产需要 ,大量处理后的水不得不向地表水体排放。研究了如何处理含油污水并使之达到排放标准。采用PAC、Al2 (SO4 ) 3、PAM等絮凝剂对油田含油污水进行混凝试验研究。试验结果表明 :PAC与PAM复配比单独使用处理效果更好 ,尤其对COD具有很好的去除作用。混凝后含油污水再经过过滤吸附处理 ,完全可以达到GB 8978 1996排放标准  相似文献   
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