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1.
蒸压加气混凝土是一种新型的节能、环保墙体材料 ,它在基本建设中运用具有良好的综合经济效益和社会效益。这里以加气混凝土在建筑中的应用实例 ,从材料、施工、抹灰及存在的问题等方面论述了它的运用情况 ,可供有关设计和施工人员参考。 相似文献
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双孢蘑菇性亲和性相关分子标记的初步筛选 总被引:4,自引:0,他引:4
以传统的形态,生理生化分析和最新的DCS-PDMA性亲和性测定方法为基础, 结合群体分离分析和RAPD技术来源于同一双孢蘑菇异核体菌株的12个不育同核原生质体个体进行分析,筛选与性亲和性相关的分子标记。研究结果表明,供试的12个不育同核原生质体个体被分成两大类性亲和性类型,其中一类(A^ )包括不育同核原生质体个体B、C、D、E、F、G、H、I、J、L,另一类(A^-)则仅仅包括不育同核原生质体个体K和M,同时筛选到一个与性亲和性相关的分子标记OPA16 1500。从而为间地利用双孢蘑菇本身特有的交配型作标记来指导杂交育种工作和进一步将性亲和性基因定位分离克隆奠定了坚实的基础。 相似文献
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马力 《湖南农业大学学报(自然科学版)》2011,37(5):479-483
采用三速和单速循环风机,研究密集烤房不同循环风机对烤烟色素及感官质量的影响.结果表明:采用三速循环风机烤后烟叶的叶绿素a、叶绿素b含量分别为5.10、167.74 μg/g,分别为单速循环风机的72.11%和93.30%;叶黄素、β-胡萝卜素、类胡萝卜素含量分别为0.84、155.56、156.40 μg/g,分别为单... 相似文献
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SoilFlex‐LLWR: linking a soil compaction model with the least limiting water range concept 下载免费PDF全文
T. Keller A. P. da Silva C. A. Tormena N. F. B. Giarola K. M. V. Cavalieri M. Stettler J. Arvidsson 《Soil Use and Management》2015,31(2):321-329
Soil compaction impacts growing conditions for plants: it increases the mechanical resistance to root growth and modifies the soil pore system and consequently the supply of water and oxygen to the roots. The least limiting water range (LLWR) defines a range of soil water contents within which root growth is minimally limited with regard to water supply, aeration and penetration resistance. The LLWR is a function of soil bulk density (BD), and hence directly affected by soil compaction. In this paper, we present a new model, ‘SoilFlex‐LLWR’, which combines a soil compaction model with the LLWR concept. We simulated the changes in LLWR due to wheeling with a self‐propelled forage harvester on a Swiss clay loam soil (Gleyic Cambisol) using the new SoilFlex‐LLWR model, and compared measurements of the LLWR components as a function of BD with model estimations. SoilFlex‐LLWR allows for predictions of changes in LLWR due to compaction caused by agricultural field traffic and therefore provides a quantitative link between impact of soil loading and soil physical conditions for root growth. 相似文献
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The response of the soil food web structure to soil quality changes during long-term anthropogenic disturbance due to farming practices has not been well studied. We evaluated the effects of three tillage systems: moldboard plow/rotary harrow (MP), rotary cultivator (RC), and no-tillage (NT), three winter cover-crop types (fallow, FL; rye, RY; and hairy vetch, HV), and two nitrogen fertilization rates (0 and 100 kg N ha−1 for upland rice, and 0 and 20 kg N ha−1 for soybean production) on changes in nematode community structure. Sixty-nine taxa were counted, total nematode abundance (ALL), bacterial feeders (BAC), predators (PRD), omnivores (OMN), and obligatory root feeders (ORF) were more abundant in NT than in MP and RC, but fungal feeders and facultative root feeders (FFR) were more abundant in RC than in NT and MP. Cover crop also influenced nematode community structure; rye and hairy vetch were always higher in ALL, BAC, FFR, ORF, and OMN than fallow. Seasonal changes in nematode community structure were also significant; in particular, as soil carbon increased, nematode abundance also increased. The relationship between nematode indices and soil carbon was significant only in NT, but not in MP and RC. In NT, with increasing soil carbon, enrichment index and structure index (SI) were positive and significant and channel index was negative. Bulk density was significantly negatively correlated with FFR and ORF. Seasonal difference in nematode community between summer and autumn was larger in an upland rice rotation than in a soybean rotation. Over the nine-year experiment, SI increased not only in NT but also in MP and RC, suggesting that repeated similar tillage inversions in agroecosystems may develop nematode community structures adapted to specific soil environmental conditions. Because NT showed the highest values of both SI and soil carbon, the increase of soil carbon in NT is expected to have a great impact on developing a more diverse nematode community structure. 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(6):475-486
Abstract Samples of four soils having a wide range of volume weights (0.65, 1.02, 1.25, 1.62 g/cm3) were either weighed or measured by volume and extracted with: (a) the Bray P1 extractant, (b) the Mehlich double acid extractant for P, K, Ca, Mg, Mn, Zn and (c) neutral N NH4OAc for K, Ca, Mg all at a soil/extracting solution ratio of 1:10. The soil test results were recorded on a volume basis in mg/dm3 and on a weight basis in mg/kg. The test values for all macronutrients obtained with all extractants decreased, relative to a constant volume, with increasing VW of soil when analyzed and expressed on a weight basis. Results based on the use of a volume sample (scooped) but calculated on an assumed weight of soil changed the values in direct ratio of 1/assumed VW. The use of an assumed VW has no justification, since uniform soil test results can be obtained when expressed on a volume basis by either using a scooped sample of known volume or a weighed sample followed by multiplication with the VW of each soil. 相似文献
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Thirty-seven bulk tank milk (BTM) and individual milk samples of all contributing cows were tested for Coxiella burnetii detection by a real-time PCR assay and used to assess the relationship between the BTM PCR-response and (i) the within-herd prevalence of milk-shedder cows and (ii) the proportion of heavy milk-shedder cows. The within-herd prevalence of milk-shedder cows (i) was found to be significantly higher in herds with a positive BTM and (ii) increased significantly with the estimated titre in Coxiella burnetii obtained in positive BTM. The proportion of heavy milk-shedder cows among the milk-shedder cows increased significantly with an increased estimated titre in Coxiella burnetii in positive BTM. Therefore, a real-time PCR assay applied to BTM samples collected repeatedly over time appears to be a valuable tool to assess on a larger scale the status of herds towards Coxiella shedding, and to evaluate the efficiency of control actions aimed at controlling and/or preventing Coxiella shedding in dairy herds. 相似文献
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