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981.
为了研究饱和效应对大孔径闪烁仪估算区域显热通量的影响,在2014年8—9月期间进行试验,以具有抗饱和性能的双光路BLS900型闪烁仪为参考,以孔径尺寸为0.075 m(文中简记为LAS1)、0.15 m(文中简记为LAS2)的中国产ZZLAS型闪烁仪为研究对象,通过光学传播原理计算出饱和修正系数,并对ZZLAS型闪烁仪的观测结果进行饱和修正分析。结果表明:LAS1的饱和修正系数为1.034,LAS2的饱和修正系数为1.019。试验观测中LAS1饱和率为24.58%,LAS2饱和率为2.04%,进行饱和修正后,LAS1的有效饱和修正率为12.87%。与BLS900相比,LAS1修正后显热通量均方根误差变为25.67 W/m2;LAS2的饱和修正率仅为0.32%,修正前后显热通量均方根误差基本无变化。进行饱和修正前,对BLS900与LAS1观测的显热通量进行F检验,未达到显著水平(P=0.15);通过计算得出的修正系数修正后,达到极显著水平(P=0.004);而利用BLS900的实时修正系数进行修正后,接近显著水平(P=0.06)。利用试验计算得出的饱和修正系数修正后,显热通量与参考标准的误差范围为1.28~53.42 W/m2,比修正前更接近BLS900的观测结果。研究对农田、人工林下垫面条件下的观测结果采用文中的饱和修正方法进行验证,结果也表明,经饱和修正后,闪烁仪观测的显热通量更接近BLS900的观测结果。当ZZLAS型闪烁仪发生明显饱和现象时,利用光学传播原理计算得出的修正系数对饱和数据进行修正效果显著。 相似文献
982.
Competitive sorption between imidacloprid and imidacloprid-urea on soil clay minerals and humic acids 总被引:1,自引:0,他引:1
Soil organic matter and clay minerals are responsible for the adsorption of many pesticides. Adsorption and competitive sorption of imidacloprid on clay minerals and humic acids (HA) were determined using the batch equilibration method. The sorption coefficient of imidacloprid on humic acids was significantly higher than that on Ca-clay minerals, indicating that soil organic matter content was a more important property in influencing the adsorption of imidacloprid. Competitive sorption was investigated between imidacloprid and its main metabolite imidacloprid-urea on HA and Ca-clay minerals. The results showed that the sorption capacity of imidacloprid on clay minerals and HA was reduced in the presence of the metabolite, implying that imidacloprid-urea could occupy or block adsorption sites of imidacloprid on soil, potentially affecting the fate, transport, and bioavailability of imidacloprid in the environment. The interactions between a Ca-clay or HA-clay mixture and adsorption of imidacloprid and imidacloprid-urea were studied using IR differential spectra on thin films made of the adsorbent. The possible mechanisms were discussed from the shift of characteristic IR absorption bands of imidacloprid and imidacloprid-urea after sorption. 相似文献
983.
城乡交错带土地利用变化及其生态效应 总被引:8,自引:1,他引:8
以泰安市岱岳区为例,运用1990年和2003年的土地利用数据,采用GIS与实地调查相结合,运用Costanza等提出的生态服务价值系数,分析了城乡交错带土地利用变化与生态服务价值的响应。结果表明:研究区1990~2003年间,建设用地、园地、水域呈增加趋势。林地、耕地、未利用土地呈减少趋势。区域生态服务总价值随土地利用类型的变化而变化,生态服务功能在气候调节、气体调节、废物处理、土壤形成与保护和食物生产等方面有所下降,而在娱乐休闲、侵蚀控制和原材料方面生态服务功能增强,说明城市的快速发展在一定程度上影响了城乡交错带的生态环境。 相似文献
984.
985.
为了实现对柴油机故障诊断系统的最小化和系统诊断模型的通用化,该文主要在机械设备的故障诊断数据处理方面,在对特征量提取算法、主特征量提取算法、神经元网络专家系统进行深入比较研究的基础上,建立了机械设备故障诊断系统统一的数据结构和模型算法,结合MATLAB的工具包实现了机械故障诊断系统(MFDS)软件包的开发。并在6135柴油机上试验,对测量取得的数据经过MFDS的学习与诊断,结果表明该系统可以快速准确地给出诊断结果,对完善柴油机等复杂机械系统的故障诊断理论和水平具有实际意义。 相似文献
986.
臭氧结合拮抗酵母对草莓采后灰霉病的控制 总被引:4,自引:2,他引:4
为了寻找一种能够代替化学杀菌剂控制草莓采后病害的方法,试验研究了臭氧与罗伦隐球酵母(Cryptococcus laurentii (Ku?erath) Skinner)结合使用对草莓采后灰霉病的控制效果的影响。研究表明,臭氧处理能显著降低草莓采后灰霉病发病率、抑制草莓水果伤口处致病菌数目和抑制霉菌孢子的萌发。经过2 d的贮藏,臭氧处理与罗伦隐球酵母结合使用草莓灰霉病的发病率为29.63%,显著低于对照处理(70.37%),同时也低于臭氧处理及罗伦隐球酵母单独处理的发病率(分别为48.15%和44.44%)。在20℃和4℃下培养,罗伦隐球酵母在水果伤口处能迅速地增长,并持续保持较高水平。臭氧处理与罗伦隐球酵母结合处理能诱导草莓果实的多酚氧化酶(PPO)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、过氧化氢酶(CAT)和b-1,3-葡聚糖酶(GLU)活性的提高,同时可以抑制脂氧合酶(LOX)活性的增加。 相似文献
987.
Li-Li Xu Wei Li Yu-Ming Wei You-Liang Zheng 《Genetic Resources and Crop Evolution》2009,56(3):377-391
The genetic variations of high-molecular-weight (HMW) glutenin subunits in 1051 accessions of 13 Triticum subspecies were investigated using sodium dodecyl sulfate polyacrylamide-gel electrophoresis. A total of 37 alleles were
detected, resulting in 117 different allele combinations, among which 20, 68 and 29 combinations were observed in diploid,
tetraploid and hexaploid wheats, respectively. Abundance and frequency of allele and combinations in tetraploid wheats were
higher than these in hexaploid wheats. Allele Glu-A1c was the most frequent subunit at Glu-A1 locus in tetraploid and hexaploid wheats. Consequently, the results also suggested that the higher variations occurred at
Glu-B1 locus compared to Glu-A1 and Glu-D1. Therefore, carthlicum wheat possessing the allele 1Ay could be presumed a special evolutional approach distinguished from other tetraploid species.
Furthermore, this provides a convenient approach of induction of the 1Ay to common wheat through direct cross with carthlicum wheat. Alleles Glu-B1c and Glu-B1i generally absent in tetraploid wheats were also found in tetraploid wheats. Our results implied that tetraploid and hexaploid
wheats were distinguished in dendrogram, whereas carthlicum and spelta wheats and however displayed the unique performance. In addition, founder effect, no-randomness of diploidization, mutation
and artificial selection could cause allele distribution of HMW-GS in Triticum. All alleles of HMW-GS in Triticum could be further utilized through hybrid in the quality improvement of common wheat. 相似文献
988.
Proper spatial and temporal treatments of climate change scenarios projected by General Circulation Models (GCMs) are critical to accurate assessment of climatic impacts on natural resources and ecosystems. The objective of this study was to evaluate the site-specific impacts of climate change on soil erosion and surface hydrology at the Changwu station of Shaanxi, China using a new spatiotemporal downscaling method. The Water Erosion Prediction Project (WEPP) model and climate change scenarios projected by the U.K. Hadley Centre's GCM (HadCM3) under the A2, B2, and GGa emissions scenarios were used in this study. The monthly precipitation and temperature projections were downloaded for the periods of 1900–1999 and 2010–2039 for the grid box containing the Changwu station. Univariate transfer functions were derived by matching probability distributions between station-measured and GCM-projected monthly precipitation and temperature for the 1950–1999 period. The derived functions were used to spatially downscale the GCM monthly projections of 2010–2039 in the grid box to the Changwu station. The downscaled monthly data were further disaggregated to daily weather series using a stochastic weather generator (CLIGEN). The HadCM3 projected that average annual precipitation during 2010–2039 would increase by 4 to 18% at Changwu and that frequency and intensity of large storms would also increase. Under the conventional tillage, simulated percent increases during 2010–2039, compared with the present climate, would be 49–112% for runoff and 31–167% for soil loss. However, simulated soil losses under the conservation tillage during 2010–2039 would be reduced by 39–51% compared with those under the conventional tillage in the present climate. The considerable reduction in soil loss in the conservation tillage indicates the importance of adopting conservation tillage in the region to control soil erosion under climate change. 相似文献
989.
摘要利用EST-SSR分子标记对大白菜种质资源基因库中686份样品所代表的1900份大白菜种质资源进行分析研究。构建大白菜种质资源的核心种质并且形成核心种质的EST—SSR指纹图谱库。结果表明利用4组鉴定白菜品种的EST—SSR的特异性标记组合,获得近158个EST—SSR多态的标记,对大白菜种质资源基因库中686份样品所代表的1900份大白菜种质资源进行核心种质的构建提供了分析数据。形成的核心种质包括168份样品,占库存资源的8.8%,它的多态位点百分率保持了原群体的100%。所构建的核心种质涵盖了原资源的绝大部分区域来源的品种,包含了早、中、晚熟品种中所有典型的大白菜类型和其相关的特征特性。并进一步进行了核心种质资源遗传多样性分析。核心种质的EST—SSR指纹图谱库中,每一份样品的指纹都是唯一的,为登记、评价、整理、分发、繁殖等种质资源库的管理和育种者对其材料的利用提供了重要的有价值的信息。EST-SSR标记组合是构建中国大白菜核心种质及其指纹图谱的经济、高效的方法。 相似文献
990.
橡胶树内生真菌ITBB2-1具有很强的抗盐性,在培养基中添加2倍海水盐度的NaCl能显著促进菌落的生长。采用两种方法研究利用花粉管通道法将ITBB2-1耐盐基因导入拟南芥。多数耐盐转基因植株畸形,生长发育不正常。通过对一千两百余株转基因植株的筛选,获得了耐盐性显著提高、生长发育正常的转基因植株3个。对主要农艺性状统计分析发现,转基因植株叶片的长度、宽度和面积均比野生型植株小,差异达极显著水平。转基因植株SR3的角果长度仅为野生型的64.5%,SR1和SR2的角果长度与野生型无显著差异。本研究表明,在真菌耐盐机制尚未得到研究和耐盐基因尚未克隆的情况下,可以采用花粉管通道法将其耐盐特性导入高等植物中。 相似文献