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861.
严明  贺少帅  汪承义  文强  何建军 《测绘科学》2016,41(9):16-19,190
针对光行差几何定位误差研究的不足,该文从光行差原理出发,推导出卫星对地观测中的光行差几何定位偏差计算公式,仿真光行差至少产生17m的几何定位偏差;然后在卫星遥感图像严密几何定位处理中,使用给出的视向量光行偏差角校正模型,实时校正严密几何定位模型中存在的光行差位置偏差,并给出校正模型。实际应用结果表明,该方法能够提高卫星遥感图像的几何定位精度。  相似文献   
862.
为研究单条胶黏藻(Dumontia simplex Cotton)的孢子发育类型和生活史,探明其孢子发育的最适环境因子,在实验室条件下,通过培养观察,研究不同温度、光照强度和盐度对其孢子(果孢子和四分孢子)早期发育的影响。结果表明:(1)孢子发育过程中无丝状体出现,孢子的发育类型为直接盘状体型。(2)温度、光照强度和盐度对其孢子的早期发育均有影响,温度6—30°C范围内,果孢子发育的最适温度为9°C,四分孢子为9—12°C;光强80—400μmol/(m2·s)范围内,果孢子发育的最适光强为160μmol/(m2·s),四分孢子为160—200μmol/(m2·s);盐度15—50范围内,孢子(果孢子和四分孢子)发育的最适盐度为30。(3)单条胶黏藻生活史由单倍的雌、雄配子体和二倍的果孢子体及四分孢子体构成,配子体和四分孢子体外形一致,交替出现,属于典型的同型世代交替。  相似文献   
863.
We conducted a study that shows that light and dark conditions do not affect the uptake rates of ammonium and nitrate by the seagrass Zostera noltei. This is an important advantage over some seaweed species in which these rates are severely reduced at night. In the light, the ammonium uptake rates were initially higher (15 and 20 μmol·g?1·h?1) and stabilized at a rate of 5 μmol·g?1·h?1 after 1 h, whereas in the dark the rates remained constant at a rate of 10 μmol·g?1·h?1 over the first 180 min of incubation. The rates of nitrate uptake in the light were high within the first 120 min of incubation (7.2–11.1 μmol·g?1·h?1) and decreased afterwards to lower values (0.8–3.9 μmol·g?1·h?1), whereas in the dark the rates fluctuated around 0.0–11.1 μmol·g?1·h?1 throughout the whole incubation time (7 h). The soluble sugar content of Z. noltei leaves increased significantly with both ammonium and nitrate incubations in the light, indicating the metabolic outcome of photosynthesis. In the dark, there was no significant variation in either the soluble sugar or in the starch content of leaves, rhizomes or roots in either the ammonium or nitrate incubations. However, the total starch content of plants decreased at night whereas the total soluble sugars increased, suggesting a process of starch catabolism to generate energy with the consequent production of smaller monosaccharide products. The starch content of rhizomes decreased significantly during the light incubations with nitrate but not with ammonium. These results suggest that carbohydrate mobilization is necessary for Z. noltei to account for extra energetic costs needed for the uptake and assimilation of nitrate. Furthermore, our results suggest that nitrate uptake, at least during the day, requires the mobilization of starch whereas the uptake of ammonium does not.  相似文献   
864.
概述了玉米连阴雨灾害的研究方法和研究现状,重点对玉米连阴雨灾害研究方法、连阴雨灾害指标、玉米耐阴指标及耐阴机理等进行了总结与评述。目前,研究已初步形成了玉米连阴雨气象灾害指标和玉米品种的耐阴性评价指标,并从玉米生长发育、光合生理、碳氮代谢和分子生物学等角度对玉米耐阴机制进行了有益的探索。但目前尚未有明确的灾损评估指标,品种耐阴性评价指标尚未统一,前人研究多注重阴雨天气带来的光辐射减弱的影响,后续研究需考虑土壤墒情和气温因素与光辐射对玉米产量的协同影响规律。加强玉米品种耐阴性评价指标的研究和耐阴种质的筛选,以减缓连阴雨灾害对玉米生产的不利影响。  相似文献   
865.
We tested 288 pieces of the polished cabochon jadeite-jade with high quality green and smooth surfaces using the colorimeter Color i5 based on the CIE 1976 L~*a~*b~* uniform color space. The color changes after alternating three CIE standard light sources D_(65),A and CWF were compared,and the degree of metamerism was evaluated. The results show that the CIE standard light sources D_(65),A and CWF increase the chroma of green and turn bluish green into vivid green,which are similar or to nearly colorless and transparent glass-like samples with fine textures. When the three light sources were individually alternated,the lightness of the jadeite-jades showed little change,but the tone changed significantly. Metamerism occurred only in 3 pairs among the 16 samples that were selected by cluster analysis for quality,and the metamerism colors were highly consistent of L~*D_(65)∈(43.47,46.75),C~*D_(65)∈(65.20,68.80) and ho~*D_(65)∈(138.10,140.23). We can conclude that the jadeite-jade green gradually turns to blue when the color temperature of the light source increases. But when considering both the light sources and the samples,D_(65) is more suitable to be the light source of jadeite-jade green when compared with the light sources CWF and A. Compared with the CIE standard green and high chroma green,high-quality jadeite-jade green has a slight yellow tone,low lightness and high chroma. The special metamerism index decreased to 1 when the light source alternated among D_(65),A and CWF. Therefore,the color of jadeite-jade green might be slightly influenced by alternating of the light sources.  相似文献   
866.
Vegetation gross primary production (GPP) is an important variable for the carbon cycle on the Qinghai-Tibetan Plateau (QTP). Based on the measurements from 12 eddy covariance flux sites, we validated a light use efficiency model (i.e. EC-LUE) to evaluate the spatial-temporal patterns of GPP and the effect of environmental variables on QTP. In general, EC-LUE model performed well in predicting GPP at different time scale over QTP. Annual GPP over the entire QTP ranged from 575 to 703 Tg C, and showed a significantly increasing trend from 1982 to 2013. However, there were large spatial heterogeneities in long-term trends of GPP. Throughout the entire QTP, air temperature increase had a greater influence than solar radiation and precipitation (PREC) changes on productivity. Moreover, our results highlight the large uncertainties of previous GPP estimates due to insufficient parameterization and validations. When compared with GPP estimates of the EC-LUE model, most Coupled Model Intercomparison Project (CMIP5) GPP products overestimate the magnitude and increasing trends of regional GPP, which potentially impact the feedback of ecosystems to regional climate changes.  相似文献   
867.
翟正  王学军  鲍燕  綦艳丽  韩冬梅  林晶  王大洋 《地质论评》2021,67(Z1):67z1133-67z1134
正东营凹陷历经近60年的勘探,已达到高勘探程度阶段,勘探层系逐渐由中浅层向深层转移。然而,相较中浅层勘探,深层油气勘探程度较低,传统的油气地球化学分析技术难以直接应用于深层油气地球化学研究,对深层油气资源潜力的认识不足。因此,本文采用了化学态生物标志化合物提取、  相似文献   
868.
The non‐aqueous phase liquid simulator was used to model and interpret the occurrence of a thin benzene‐contaminated soil layer 9.0 m below the groundwater table in an abandoned gas plant site. The simulator was first evaluated in column tests under similar conditions to the contaminated site. Saturation–capillary pressure (S–P) relationships were extended from the laboratory scale of the column tests to the field scale of the subsurface at the abandoned site. Dynamic boundary conditions were established in order to prevent the model from generating excessive vertical velocities. The modelled benzene layer formation process agreed well with the in situ observations. With falling and then rising of the water table, benzene release from the surface migrated downward and then upward and distributed itself below and above the water table. Biochemical degradation of benzene made the distribution discontinuous in the subsurface. These two factors resulted in the thin benzene‐contaminated layer below the groundwater table. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
869.
青海省草地资源净初级生产力遥感监测   总被引:8,自引:1,他引:7  
在研究特定区域的草地光能利用率和环境影响因素典型特点的基础上,建立基于光能利用率的草地NPP遥感估算模型,模拟并分析2006年青海省草地FPAR、光能利用率、NPP的空间分布和季相变化特征。研究结果表明,2006年青海省草地净初级生产力平均值为173.28 gC/(m2.a)。青海省东南部、南部和青海湖周围三个地区,是青海省草地NPP较高的区域。不同草地类型的NPP存在差异,高覆盖度草地的单位面积平均NPP为193.82 gC/(m2.a),中覆盖度草地NPP为157.14 gC/(m2.a),低覆盖度草地NPP为121.08 gC/(m2.a)。  相似文献   
870.
针对现有三维地图在光照与阴影表达上存在的表现手法单一、调节功能欠缺、认知作用有限等诸多不足,从色彩学的角度探讨光照与阴影的颜色随经纬度和时间变化而变化的规律,充分考虑人们的空间认知习惯,建立一种简单可行的三维地图光影模型,可以非常方便、逼真地模拟任何地方的光照与阴影时空变化过程及规律,为人们在使用已有三维建模软件或利用组件式技术开发三维地图可视化软件时提供依据,以增强三维地图的视觉表达效果。  相似文献   
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