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991.
肉类腐败变质时菌落总数(SPC)临界值的研究 总被引:1,自引:0,他引:1
本研究各用五组猪、牛、羊肉、在常温下置放,然后比较其感官指标、微生物指标、理化指标、测定肉类腐败变质时的菌落总角定其腐败变质时的临界值,借以快速确定肉类商品的货架期是否已经结束。 相似文献
992.
在测试并确定农业生态系统各项参数和状态变量的基础上, 应用数学模型方法建立了松嫩平原玉米带农业生态系统的能流型, 进行了结构与功能的分析, 探讨了不同农业技术模式、土壤有机质和农田产量之间消长的关系。结果认为, 实现农业的持续发展, 应采取有机无机相结合的农业技术体系。 相似文献
993.
994.
L. Z. Liang X. Q. Zhao X. Y. Yi Z. C. Chen X. Y. Dong R. F. Chen R. F. Shen 《Soil Use and Management》2013,29(2):161-168
Intensive vegetable cultivation has developed very rapidly in China, and investigation of current soil nutrient problems in vegetable fields and their potential environmental risk is important for local soil nutrient management strategies. Three hundred and sixty‐six soil samples were collected from greenhouse vegetable fields, open vegetable fields and rice/wheat rotation fields in southern Jiangsu Province, the most intensive vegetable‐producing areas in Yangtze River Delta, China, for the analysis of their soil fertility status. Soil acidification and P enrichment were the main problems identified in this area of vegetable production, with about 20 and 17% of the open and greenhouse vegetable field soils, respectively, being extremely acid with soil pH values below 5.0. In contrast, no soils under rice/wheat rotation fields were as acidic. Percentages of sites with Olsen‐P concentrations < 90 mg/kg were 61, 85 and 0% for soils growing greenhouse vegetable, field vegetable and rice/wheat, respectively. The nitrogen (N) surplus for vegetable fields exceeded 170 kg/ha/crop, and the phosphorus (P) surplus exceeded 40 kg/ha/crop. Thus, current vegetable production leads to potential environmental risks of N and P pollution of nearby aquatic bodies. Insufficient supplementation with potassium fertilizers was found in some vegetable fields. Several ameliorative measures are proposed. 相似文献
995.
R. E. Jaimez O. Vielma F. Rada C. García-Núñez 《Journal of Agronomy and Crop Science》2000,185(2):113-119
The degree of crop sensitivity to water deficit, during the different developmental stages of a plant, is an important aspect to consider in tropical semiarid regions. The effect of water deficit on flowering dynamics and fruit production of sweet pepper (Capsicum chinense) was evaluated under several water regimes, during three consecutive years. A complete randomized block design with three replicates was employed. Flowering dynamics and fruit production were measured weekly, and water potentials were obtained twice during the experiments. For all years, flowering began at approximately 70 days after transplanting. In the most favourable year (trial 1996), there were no differences in total flower and fruit production in terms of irrigation frequency. For the other less favourable years, flowering and fruit production were significantly different between irrigation frequencies. Our results show that low water availability, prior to flowering, reduces the number of flowers produced and retards the occurrence of maximum flowering. On the other hand, a water deficit during the period between flowering and fruit development reduces final fruit production. This suggests that a water deficit during this last stage affects final yield to a greater extent. 相似文献
996.
由于我国档案价值鉴定理论和观念的长期滞后,导致人们在认识上存在许多“误区”。一、对“丰富馆藏”的理解片面,效益观念淡漠;二、忽略了对永久、长期档案的价值鉴定;三、档案价值鉴定是否重要是由档案数量的多少来决定的;四、鉴定难,销毁更难。文章详细探讨了产生这些“误区”的原因,以及由此带来的负面效应,并提出了正确的认识和今后努力的方向。 相似文献
997.
杂交粳稻泗优422制种特性探讨 总被引:1,自引:0,他引:1
观察了731A、六千辛A、轮回422、77302的开花习性,并对其相互杂交的结实率进行了调查。与六千辛A相比,731A开花持续天数较短,开颖角度较小,柱头外露率低,开闭时间略长。在相同授粉条件下,731A与轮回422的结实率低于六千辛A与77302。 相似文献
998.
曾福生 《湖南农业大学学报(自然科学版)》1997,23(1):83-87
在分析了结构变革与农业增长方式转变关系的基础上,提出了结构优化的经济学原理,并探讨了我国农业经济结构调整的具体方向。 相似文献
999.
阐述了在胶南自然条件下生产无公害绿茶的主要技术,从环境选择、地力改善、肥料施用、病虫害管理等方面进行了详细的论述,为江北无公害绿茶生产提供了良好的借鉴。 相似文献
1000.
Changes in the bone mineral content (BMG) during the first 4 lactations were continuously studied between July 1977 and February 1982 in a total number of 103 dairy cows of different breeds and rearing intensities. The BMG was measured by dichromatic photon absorptiometry in 2 coccygeal vertebrae. Although great individual variations were found, the changes in BMG during the lactation followed a typical pattern with high values during the dry period and low values after calving and during mid-lactation. The influence of body weight on the BMC value is discussed. The changes in BMC were more accentuated during the first lactation, as compared to the subsequent lactations. This could indicate a metabolically more active skeleton in younger cows. In this study no difference in BMC pattern was observed between cows affected or not affected by parturient paresis. 相似文献