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141.
为探讨不同生草年限梨园土壤钙、镁、铁、锌、锰含量变化,在东营市孤岛镇12年生‘黄金梨’[Pyrus pyrifolia (Burm.f.) ‘Nakai’]种植园,设置生草3年、生草4年和生草8年3个处理,以清耕梨园为对照,通过电感耦合等离子体发射光谱仪分别测定株间和行间表层(0~20 cm)和亚表层(20~40 cm)土壤钙、镁、铁、锌、锰的含量。梨园生草后,土壤全钙、全镁、全铁、全锌、全锰含量均有所升高。株间表层(0~20 cm)土壤分别升高25.35%~58.00%,8.83%~24.73%,15.30%~40.55%,17.93%~57.94%,11.86%~28.12%;株间亚表层(20~40 cm)土壤升高11.44%~39.08%,3.17%~38.53%,6.69%~38.25%,17.87%~57.12%,3.31%~34.00%;行间表层(0~20 cm)土壤升高24.36%~53.05%,31.70%~63.81%,33.58%~66.05%,24.34%~55.81%,35.79%~73.21%;行间亚表层(20~40 cm)土壤升高18.29%~52.92%,27.77%~69.69%,27.45%~72.19%,19.02%~62.75%,32.70%~81.69%。梨园生草后能显著提高土壤各层全钙、全镁、全铁、全锌和全锰含量,且均表现为生草8年>生草4年>生草3年>清耕。土壤全钙、全镁、全铁、全锌、全锰含量在不同土层中表现不一,但多随土壤深度增加而升高,且行间含量高于株间。 相似文献
142.
城中村是我国快速城市化进程中的一个特殊产物,通常存在人口密集、建筑私自改造等问题。开展城中村的识别和监测对城乡统筹规划以及精细化治理等具有重要意义。基于深度学习提出了一种新的城中村遥感识别模型,该模型包括一个多尺度扩张卷积模块和一个非局部特征提取模块,前者能够聚合多层级空间特征以适应城中村形状、尺度的变异性;后者用于提取全局语义特征以提高城中村的类间可分性。选取北京市二环与六环之间的区域作为研究区,实验结果表明本文模型取得了较好的识别效果,总体精度可达94.27%,Kappa系数为0.8839,且效果优于传统模型。本文研究表明,基于多尺度扩张卷积神经网络进行城中村遥感识别是可行且有效的,可为城乡统筹规划提供精确的城中村空间分布数据。 相似文献
143.
通过对比生物质、燃煤及两者1∶1的混合燃料在燃煤炉具中采暖及炊事两种工况下的能量效率、排放特征及经济性能,具体量化生物质混燃的技术优势,为清洁低廉的生物质能在农村地区的推广提供理论依据。结果显示,在燃煤炉具中混合燃料燃烧时的能源效率明显高于生物质燃料,且其采暖工况效率高于炊事工况效率近20%。相比于燃煤,混燃时主要气态污染物SO2、NO、NO2综合减排效果良好,PM2.5排放量远低于国标限值(100mg/MJ)。其主要有机污染排放PAHs也能得到有效控制,尤其是高环PAHs在采暖和炊事工况下的减排率可分别达到34%和87%。而相比于生物质,混燃时CO排放较少,在采暖工况下减排率为46%,炊事工况则为61%。此外由于人为操作较少,采暖工况下的污染排放量较为稳定。混合燃料价格较低,单位能量价格为0.039元/MJ,而单位质量价格仅为燃煤的1/2,燃烧器可使用低成本燃煤炉具,避免使用价格昂贵的生物质专用炉具,可确保低收入家庭居民日常用能支出维持在经济承受能力范围之内。 相似文献
144.
通过添加不同浓度猕猴桃汁、香蕉汁、梨汁、苹果汁、白萝卜汁、胡萝卜汁、土豆汁、红薯汁等8种有机物及柠檬酸钠组合,研究其对春兰根状茎增殖及抗褐化效果的影响。结果表明,单独添加猕猴桃汁100.0 g·L-1、梨汁100.0 g·L-1或柠檬酸钠1.0 g·L-1比对照能显著促进根状茎增殖,增殖中生长倍数分别为3.9、2.4和2.2,梨汁和猕猴桃汁处理中,根状茎中细胞分裂相关基因CgCki、CgCKS、CgClins、CgE2F和CgRb表达量显著提高。1/2MS+NAA5.0 mg·L-1+活性炭1.0 g·L-1+猕猴桃汁100.0 g·L-1+柠檬酸钠1.0 g·L-1组合对春兰根状茎增殖及抗褐化效果最好,根状茎增殖的生长倍数为4.2,细胞分裂相关基因CgCDKS、CgCki、CgCKS、CgClins、CgE2F和CgRb表达显著提高。因此,在春兰组培快繁过程中猕猴桃汁+柠檬酸钠组合可以有效地促进根状茎增殖,并防止根状茎褐化。 相似文献
145.
146.
G.D. Hallowell DipACVIM T.J. Potter BVetMed I.M. Bowen PhD 《Journal of Veterinary Cardiology》2007,9(2):91-98
ObjectiveThe objective of the study was to report normal ultrasonographic appearance and intra-cardiac dimensions in two dairy breeds and to calculate cardiac output (CO) using echocardiography.BackgroundIntra-cardiac dimensions, time indices and CO estimation have not previously been reported in adult cattle.Animals, materials and methodsEchocardiograms were obtained from healthy adult dairy cows (10 Jersey (J) and 12 Holstein Friesians (HF)) in the body weight range of 400 to 700 kg. Standard echocardiographic images were obtained from the left and right hemithoraces. Velocity time integrals were obtained in order to calculate CO using pulsed wave Doppler of aortic flow in the J cows. Measurements obtained included pulmonary artery and aortic diameters, left and right ventricular diameters (and calculated fractional shortening and left ventricular ejection fraction), left atrial size and time indices assessing valve function.ResultsHF cows had significantly (p < 0.05) larger pulmonary artery and aortic diameters, larger left atrial diameters and left ventricular internal diameters during diastole, but these were not different when corrected for body weight. Left and right ventricular dimensions, adjusted for body weight, were significantly larger (p = 0.02 and p = 0.035 respectively) in J cows when compared to HF cows. No differences were noted in the time indices between the two groups. No significant differences were noted in intra-operator variability and the only significant difference in inter-operator variability was in measurement of the pulmonary artery (p = 0.03; ICC = 0.63).ConclusionsIt is possible to obtain repeatable, reliable echocardiograms in order that meaningful intra-cardiac dimensions can be obtained in adult dairy cattle. 相似文献
147.
P N Olson R A Bowen P W Husted T M Nett 《American journal of veterinary research》1981,42(9):1618-1620
A specific radioimmunoassay was used to measure concentrations of hydrocortisone (cortisol) in the serum and plasma of 4 dogs. Differences (P greater than 0.05) in concentrations of cortisol were not found between serum and plasma (from EDTA-treated and heparinized blood samples). Differences (P greater than 0.05) in serum or plasma concentrations of cortisol were not found between samples stored at 4 C for various times (10 minutes, 10 hours, 40 hours) after collection, but before removal of RBC. In a study designed to determine the stability of cortisol in serum samples stored at room temperature, degradation was dependent on the initial serum concentrations of cortisol. Decreases (P greater than 0.05) did not occur in concentrations of cortisol in serum samples stored up to 15 days when initial concentrations of cortisol were less than 15 ng/ml. However, when initial concentrations of cortisol were approximately 55 ng/ml and 80 ng/ml, significant (P greater than 0.05) degradation occurred after 9 and 5 days of storage, respectively. Results of this investigation indicate that either serum or plasma of dogs is suitable for radioimmunoassay of cortisol and that samples (with and without added coagulants) incubated at 4 C may be left uncentrifuged for up to 40 hours without cortisol degradation. However, prolonged storage of serum at room temperature is detrimental, particularly for samples having large concentrations of cortisol. 相似文献
148.
149.
150.
Bowen IS 《Science (New York, N.Y.)》1960,131(3401):649-650