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981.
982.
圆紫菜人工色素突变体的诱导与分离 总被引:1,自引:0,他引:1
为获得圆紫菜人工色素突变体,本文使用一定剂量的紫外线辐照其叶状体,培养数天后,在叶状体上出现了少量颜色变异细胞,它们呈斑点状无规则地分布在野生型细胞中间。再培养2~3周,这些色素变异细胞分裂形成了不同颜色的细胞块,其颜色呈浅绿黄、橄榄色、草绿、绿褐、黄褐、浅褐、深紫红和浅紫红色等。在辐照强度0~80 μW/cm2范围内,叶状体上色素变异细胞块出现的频率随辐照强度的增加而增加,但增加至80 μW/cm2以上时,随着辐照强度的增加,色素变异细胞块出现的频率反而下降,这表明80 μW/cm2为有效的辐照强度。将色素变异细胞块切下,置入充气瓶内充气培养,待其释放出单孢子,随后从单孢子萌发体中挑选出了黄褐、橄榄色、红色、褐红等纯色的突变体,并利用叶状体单性生殖分别获得它们的遗传纯合丝状体(品系)。各突变品系的F1叶状体与各自母体的颜色一样,说明其颜色是可稳定遗传的。与野生型品系相比,各色素突变品系的F1叶状体的生长速度、活体吸收光谱、3种主要光合色素和色素蛋白的含量及它们相互间的比值均发生了明显改变。 相似文献
983.
在InSAR干涉图数据处理过程中,通常会由于轨道参数不准确而导致去平地效应后,干涉图中仍残留部分线性相位。为避免线性趋势对数据处理结果精度的影响,提出了一种基于干涉图条纹频率检测的去除线性趋势精化方法:首先,通过Chirp Z变换精化干涉图条纹频率估计,计算出精确到0.1的线性相位条纹数;然后,模拟线性相位并从干涉图中去除。利用通过模拟和真实数据对提出的方法进行验证分析,实验结果表明:该方法能够更加彻底地去除干涉图中残留的线性趋势,对提高InSAR技术的监测精度具有一定意义。 相似文献
984.
Clarifying the distribution and dynamics of soil moisture during the freeze–thaw process is crucial for surface ecology and is an objective requirement to investigate the mechanism of changes during the groundwater recharge process in a freeze–thaw zone. Based on the monitoring data of soil moisture and temperature in the Changbai Mountain area, the freeze–thaw process is classified into four periods. This study investigates the hydrothermal migration processes during different periods. The simultaneous heat and water model is used to simulate and analyse the infiltration of soil moisture into groundwater under five precipitation insurance rates. The results are as follows: (1) The smaller the soil depth, the stronger is the correlation between soil temperature and air temperature during the freeze–thaw process. (2) The redistribution of soil moisture before and after freeze–thaw is significantly affected by the soil texture, and soil permeability affects the recharge of soil moisture from the upper region to the lower region during the thawing period. (3) Groundwater receives vertical infiltration recharge mainly during non-freezing and is supplied by freezing and snowmelt recharge during the stable thawing period. The percentage of soil water infiltration during the stable thawing period in the total annual infiltration increases gradually with the precipitation insurance rate. 相似文献
985.
Against the background of climate change, the global carbon and water cycle has undergone significant changes, and it is of great significance to explore the interrelationships of the carbon and water cycles in different regions to cope with future climate change. In this study, based on gross primary productivity (GPP) and precipitation (PRE) data, the precipitation use efficiency (PUE) of the Loess Plateau (LP) was calculated, and the Sen trend analysis and Mann-Kendall test were used to analyse the temporal and spatial variation characteristics of PUE, as well as the first-order difference method was used to derive the relative contributions to quantify the impact of vegetation growth and meteorological factors on PUE. The results show that (1) from 2001 to 2018, the spatial distribution pattern of vegetation PUE exhibited an increasing trend from northwest to southeast. On the time scale, the multi-year average value of PUE was 1.17 gC m−2 mm−1, showing an overall upward trend. Among the different land cover types, paddy fields had the highest PUE level, and sparse grassland had the lowest; (2) LAI had the highest relative contribution to vegetation PUE, followed by temperature (Temp), net radiation of the ground surface (RN), specific humidity (Shum), and wind speed (WS). LAI contributes positively to 88.9% of the area. RN positively influences high-altitude areas, while Shum had a larger area with a negative contribution. The contribution of Temp increases from northwest to southeast, and WS has balanced positive and negative contributions; (3) LAI is the dominant factor for the spatial and temporal variation of PUE in the LP, and the size of the areas where different meteorological factors dominate the changes of PUE are as follows: WS > Shum>RN > Temp. At high altitudes, the dominant meteorological driver is WS, while at low altitudes, the dominant climate driver is Shum. This study is of guiding significance for the ecological restoration and management of the LP, and it can also provide a scientific basis for the improvement of ecosystems and the sustainable management of water resources in the context of global climate change. 相似文献
986.
987.
988.
我国洞体应变固体潮调和分析结果 总被引:3,自引:1,他引:2
本文扼要介绍了我国洞体应变观测现状,公布了18个台站的调和分析结果,同时公布了国外同类仪器优质台站的计算结果,以作比较。 相似文献
989.
990.