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151.
152.
Drying Enhancement of Rough Rice by an Electric Field 总被引:4,自引:0,他引:4
Corona discharge produced by a multiple point-to-plate high-voltage electric field (HVEF) was used to investigate the enhancement of rough rice drying and its effect on rice fissuring and germination. The HVEF consisted of a 16 needle point cathode with a direct current power supply, and a grounded stainless steel plate anode. The drying rate of the treated rough rice was notably greater than that of the control, and the drying rate was described by an exponential model. There was a good agreement between the predicted and experimental results (coefficient of determination R2=0·98). The electric field treatment significantly enhanced drying but had no effect on rice fissuring at a lower temperature. The average drying rate of the treated rice increased 2·83, 1·59 and 1·63 times at 25, 40 and 50°C, respectively, compared to the corresponding control. The drying rate also increased with increasing electric field strength. The electric field treatment did not have significant effects on the percentage of kernels having heavy fissures or the germination rate of rough rice (probability P>0·05). The total number of fissured kernels in the treated sample was increased compared to the control. 相似文献
153.
Grazing intensity alters soil respiration in an alpine meadow on the Tibetan plateau 总被引:2,自引:0,他引:2
Grazing intensity may alter the soil respiration rate in grassland ecosystems. The objectives of our study were to (1) determine the influence of grazing intensity on temporal variations in soil respiration of an alpine meadow on the northeastern Tibetan Plateau; and (2) characterise the temperature response of soil respiration under different grazing intensities. Diurnal and seasonal soil respiration rates were measured for two alpine meadow sites with different grazing intensities. The light grazing (LG) meadow site had a grazing intensity of 2.55 sheep ha−1, while the grazing intensity of the heavy grazing (HG) meadow site, 5.35 sheep ha−1, was approximately twice that of the LG site. Soil respiration measurements showed that CO2 efflux was almost twice as great at the LG site as at the HG site during the growing season, but the diurnal and seasonal patterns of soil respiration rate were similar for the two sites. Both exhibited the highest annual soil respiration rate in mid-August and the lowest in January. Soil respiration rate was highly dependent on soil temperature. The Q10 value for annual soil respiration was lower for the HG site (2.75) than for the LG site (3.22). Estimates of net ecosystem CO2 exchange from monthly measurements of biomass and soil respiration revealed that during the period from May 1998 to April 1999, the LG site released 2040 g CO2 m−2 y−1 to the atmosphere, which was about one third more than the 1530 g CO2 m−2 y−1 released at the HG site. The results suggest that (1) grazing intensity alters not only soil respiration rate, but also the temperature dependence of soil CO2 efflux; and (2) soil temperature is the major environmental factor controlling the temporal variation of soil respiration rate in the alpine meadow ecosystem. 相似文献
154.
为防止盆地低洼处出现盐渍化、节约水资源,用数值模拟和田间中子仪试验相结合的方法,研究了内蒙古孪井灌区包气带的水分运移规律.数学模拟结果与田间实测土壤含水率吻合良好.在此基础上模拟计算出漫灌与喷灌条件下不同灌溉量和不同蒸发量对水分运移的影响以及水分随时间在深度上的分布情况,结果表明1200m/hm2喷灌定额下得农田水分无效消耗最小,从而得出节水高产的喷灌灌溉模式. 相似文献
155.
2004年在我国西南地区的新垦红壤山地建立了烟草基地,该基地的地理位置是N26°28′~29′,E101°51′~53′,开发总面积约为267hm2。2005年和2006年连续两年基地的烤烟都出现了大面积的烟叶呈‘倒勺子状’翻卷的症状,初步诊断是生理缺钙所致[1~3]。已有研究[2,3]从田间考察、对土壤和有机肥的检测、病株的组织分析以及水培试验等证明该症状是由于使用了一种含有过量磷酸根、硫酸根等阴离子的商品有机肥1号(是某肥料厂专门为该基地生产的一批有机肥)所诱发的,其机理是过量的磷酸根和硫酸根与根际土壤中本来就不富裕的有效钙反应形成磷酸钙沉淀和难溶性的硫酸钙,使烟株难以吸收足够的钙而诱发缺 相似文献
156.
韭菜栽培品种遗传多样性的ISSR和RAPD研究 《勤云标准版测试》2005,(4)
利用RAPD(RandomAnaplifiedPolymorphicDNA)和ISSR(Inter-simpleSequenceRepeat)两种分子标记技术对20份韭菜栽培品种进行了遗传多样性研究。结果表明,筛选后选用的12个ISSR引物和15个RAPD引物分析分别产生了258和101条扩增产物带,其中多态性条带(即20个韭菜品种中一个或多个但不是全部具有的带)分别为132和40条,分别占总数的51.2%和39.6%。,也就是说12个ISSR引物和15个SSR引物对韭菜不同品种的扩增可分别产生51.2%和39.6%的多态性带。根据两种标记的结果,利用NTSYS软件计算Nei氏遗传距离,然后以Nei氏遗传距离矩阵按UPGMA方法进行聚类分析,发现供试材料之间具有较低的遗传多样性。其品种间遗传距离分别只有0.02-0.2和0.04-0.13,且大部分品种并没有按来源省份聚在一起。鉴于此,又对两种标记的多样性分析结果利用Mantel(1968)检验进行相关性检测,发现两种结果存在较低的相关性:r=0.47174,P<0.05。 相似文献
157.
158.
159.
Dawei Yu Jiayao Feng Huimin You Shipeng Zhou Yan Bai Jincan He Hua Cao Qishi Che Jiao Guo Zhengquan Su 《Marine drugs》2022,20(1)
Chitosan obtained from abundant marine resources has been proven to have a variety of biological activities. However, due to its poor water solubility, chitosan application is limited, and the degradation products of chitosan oligosaccharides are better than chitosan regarding performance. Chitosan oligosaccharides have two kinds of active groups, amino and hydroxyl groups, which can form a variety of derivatives, and the properties of these derivatives can be further improved. In this review, the key structures of chitosan oligosaccharides and recent studies on chitosan oligosaccharide derivatives, including their synthesis methods, are described. Finally, the antimicrobial and antitumor applications of chitosan oligosaccharides and their derivatives are discussed. 相似文献
160.
生物入侵机理研究进展 总被引:4,自引:0,他引:4
综述生物入侵机理的生态学研究、生理学研究、分子生物学研究,并展望今后的研究方向。 相似文献