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51.
Mak-Mensah Erastus Zhao Wucheng Zhou Xujiao Zhang Dengkui Zhao Xiaole Wang Qi Obour Peter Bilson 《Journal of Soils and Sediments》2022,22(10):2750-2764
Journal of Soils and Sediments - On a global scale, water resources are under intense stress due to climate change. It is, therefore, crucial to understand how in situ water harvesting techniques... 相似文献
52.
通过向玉米辽旅群体中导入血缘相近、脱水速率快的9份欧美种质,构建成含有不同比例欧美种质的3份旅欧群体,能显著改善收获时含水量、出籽率、生育期、穗粗和穗行数等重要性状,且保持原始群体优良的产量一般配合力,显著提高出籽率、穗长和行粒数的一般配合力。杂种优势分析结果表明,旅欧群体所配制的组合有效提升出籽率、收获时含水量、生育期和其他穗部性状的杂种优势,与塘四平头类群的杂优模式存在极高的产量应用潜力,为改良本土种质资源适宜机械化收获和探索欧美种质新的杂优模式奠定基础。 相似文献
53.
Soil water affects transpiration response to rainfall and vapor pressure deficit in poplar plantation 总被引:2,自引:0,他引:2
Lixin Chen Zhiqiang Zhang Tonggang Zha Kangle Mo Yan Zhang Xianrui Fang 《New Forests》2014,45(2):235-250
Influences of environmental factors on transpiration are interactive. Sensitivities of transpiration responses to both evaporative demand and rainfall under contrasting soil water conditions constitute the physiological basis of the drought tolerance of trees. Such knowledge is practically significant for plantation management, especially for irrigation management. We therefore conducted a 6-year study on the transpiration of a poplar plantation in temperate China to elucidate the existence and pattern of the influence of the soil water over stand transpiration responses to (1) vapor pressure deficit (VPD), the major indicator of air dryness and (2) the rainfall, in terms of total amount and event size. The results showed that the response of plantation transpiration (E c ) to VPD was conditioned by soil moisture. There was a significant difference in the frequency distribution of maximum sap flux under contrasting soil relative extractable water. E c after rainfall of different sizes varied under similar VPD. The increasing occurrences of only large rainfall events led to enhanced total E c during the growing season, but prolonged rainless intervals did not lead to a continuous decrease of E c , suggesting appreciable supplements from the soil water were present to sustain transpiration. In addition, the balance of soil water between replenishment and extraction also conditioned the influence of rainfall over subsequent E c during the respective rainless intervals. Based on the E c responses to VPD and rainfall under different soil moisture levels, irrigation that directly replenishes the deep soil layers in order to alleviate water stress on transpiration during the small-rain event-dominated growing season is an effective and water-saving approach to guarantee trees survival during drought period. 相似文献
54.
甩挂运输作为一种节能减排、低碳高效的运输方式,也是我国目前大力倡导推行的运输方式之一,甩挂运输不仅是发展低碳物流的手段,也是企业提高工作效率,获得更大的经济效益和社会效益的可行之举.在国家政策和行业发展的推动下,甩挂运输必将成为运输行业的发展趋势.本文对甩挂运输的工作原理进行介绍,并针对甩挂运输的车队运营组织模式进行分析,将其分为4大类.结合图像对每一类运营组织模式的特点进行研究,并通过实例分析,得出该类模式的适用情况.通过系统的比较和分析这4种不同的车队组织运营模式,从理论上为物流运输企业开展甩挂运输的车队运营组织模式选择提供决策依据. 相似文献
55.
Proliferative kidney disease (PKD), caused by the myxozoan endoparasite Tetracapsuloides bryosalmonae, is of serious ecological and economical concern to wild and farmed salmonids. Wild salmonid populations have declined due to PKD, primarily in rivers, in Europe and North America. Deep lakes are also important habitats for salmonids, and this work aimed to investigate parasite presence in five deep Norwegian lakes. Kidney samples from three salmonid species from deep lakes were collected and tested using real-time PCR to detect PKD parasite presence. We present the first detection of T. bryosalmonae in European whitefish in Norway for the first time, as well as the first published documentation of the parasite in kidneys of Arctic charr, brown trout and whitefish in four lakes. The observed prevalence of the parasite was higher in populations of brown trout than of Arctic charr and whitefish. The parasite was detected in farmed, but not in wild, charr in one lake. This suggests a possible link with a depth of fish habitat and fewer T. bryosalmonae-infected and PKD-affected fish. Towards a warmer climate, cold hypolimnion in deep lakes may act as a refuge for wild salmonids, while cold deep water may be used to control PKD in farmed salmonids. 相似文献
56.
本研究从广西花坪自然保护区采集的土壤中筛选获得了一株产糖化酶丝状真菌菌株57-45,通过形态学观察和真菌内转录间隔区(internal transcribed spacer,ITS)序列比对分析,将其初步鉴定为曲霉属(Aspergillus sp.)的一个种。纯化真菌57-45所产的一种胞外糖化酶经过硫酸铵分级沉淀、疏水层析和阴离子交换层析三步蛋白质纯化步骤,得到在SDS-PAGE上约60kD的单一蛋白质条带,薄层层析分析表明该纯化的蛋白质水解可溶性淀粉的产物只有葡萄糖,证明该纯化的蛋白质为糖化酶。纯化的糖化酶Km值为1.9mg/mL,Vmax为4148μmol/(min·mg),最适作用pH5.5,最适作用温度50℃,在同步糖化发酵中有应用的潜力。金属离子Fe3+、Zn2+、Cu2+对酶活有较强的抑制作用,EDTA对酶活有较强的促进作用。本文结果将为进一步研究曲霉糖化酶的酶学特性提供新的材料。 相似文献
57.
从GenBank中获取新型甲型H1N1流感病毒(2009年流行株)HA和NA基因序列,通过多重序列比对之后,设计合成H1和N1基因特异性的引物和探针,用来建立新的甲型H1N1亚型流感病毒的多重实时RT-PCR检测方法.合成的两条荧光探针分别标记FAM和CY5荧光报告基团,荧光淬灭均使用BHQ基团.多重实时RT-PCR实验在ABl7500实时PCR仪上进行,经过40个循环的扩增之后,阳性对照出现标准的S型曲线,并且具有良好的特异性,可以很好地将新的甲型H1N1与传统的甲型H1N1以及H3N2、H5N1、H6N2和H9N2等流感病毒区分.多重实时RT-PCR可以检测到10个拷贝的模板,灵敏度接近检测方法的极限.检测时间短,从加样到反应结束只需要90 min.在对243例发热病人临床样品检测过程中发现7例阳性,1351份猪临床样品检测中未发现阳性,该检测结果和采用中国检验检疫科学研究院研制的试剂盒获得的检测结果一致.本研究所建立的快速、准确和高敏感性的多重实时RT-PCR方法非常适用于新型甲型H1N1流感病毒的实验室筛查. 相似文献
58.
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60.
Mathew J. Reeves Charles R. Curtis Mo D. Salman John S. Reif Ted S. Stashak 《Preventive veterinary medicine》1990,9(4):241-257
A survey of 1965 equine colic cases was conducted from August 1985 to July 1986 ten equine referral hospitals located througout the U.S.A. Two-thirds of the cases were randomly selected for model development (1336), while the remaining cases (629) were used only for subsequent validation of the model. The following outcomes were defined: (1) died or killed prior to discharge from the hospital; or (2) alive at the time of discharge. Only variables which were significant (P<0.05) in an initial bivariate screening procedure and for which there were less than 400 missing values were considered in the multivariable modelling. A multivariable logistic regression model was constructed using a stepwise algorithm. The model used 666 cases and included the following variables: peripheral pulse (normal or weak), pulse rate, surgical or medical treatment, packed cell volume, self-inflicted trauma (absent or present) and capillary refill time. For each horse in the validation data set which had the appropriate variables recorded (n=335), the estimated expected probability of death (expected value) was calculated using the logistic regression equation. Using Bayes theorem, the post-test probability was calculated from the expected value (an estimate of the test odds) and the present probability (the case-fatality rate at each institution). Nomograms of predictive values for different case-fatality rates and expected values were constructed. Hosmer-Lemeshow goodness-of-fit statistics indicated that the model fitted the model data set well but the validation set poorly. However, when the observed case-fatality rates were compared with the average post-test probabilities for 0.10 increments of post-test probability, qualitatively, the model's performance was better. 相似文献