Characterization of a new lectin involved in the protoplast regeneration of <Emphasis Type="Italic">Bryopsis hypnoides</Emphasis>

A group of coenocytic marine algae differs from higher plants,whose totipotency depends on an intact cell(or protoplast).Instead,this alga is able to aggregate its extruded protoplasm in sea water and generate new mature individuals.It is thought that lectins play a key role in the aggregation process.We purified a lectin associated with the aggregation of cell organelles in Bryopsis hypnoides.The lectin was ca.27 kDa with a pI between pH 5 and pH 6.The absence of carbohydrate suggested that the lectin was ...     

�й���½�ٶȳ�ģ�ͽ��������о�

???й?????????????????????????????????5?????壬????????????????С???????÷?????С?????????????????????3????????????????о??й?????????????????????????????????????????????????????С???????÷????????壨??????????????????壩????????????????????|?????????????????????????????????????????????????С???????÷?????й????1°×1°?????????????????????????????????С??     

机载LiDAR生成亚热带森林林下DTM的地面误差分析

目前LiDAR技术已经成为DTM的主要生产方法。地面误差对LiDAR生成DTM的精度影响比较明显,特别是由于亚热带森林植被覆盖区LiDAR激光点云少,生成的DTM更复杂,需要分析地面误差对LiDAR生成林下DTM的精度影响。本文以华南农业大学增城教学科研基地为研究对象,从森林郁闭度和坡度两个方面探讨了地面误差对机载LiDAR数据生成林下DTM精度的影响。研究结果发现高程误差会随郁闭度的增大而增大;而随坡度变化趋势不明显,但是坡度为15°时成为误差的分水岭,其前后误差差异比较明显。总体而言,郁闭度的影响更为明显。     

广西两系杂交稻制种安全期气候分析

根据两系杂交水稻制种对气象条件的要求 ,利用广西 80多站的气象资料 ,统计分析了广西各地两系杂交水稻制种的安全期 ,提出了广西杂交水稻安全制种应注意的一些气候问题     

基岩地区地源热泵系统浅层地热地质条件评估工作方法

在北京地区建设地源热泵系统之前,需要开展浅层地热地质条件评估,以作为政府部门为地源热泵系统立酉备案的必要的技术文件,是一项专业前期可行性研究工作。其评估工作方法和内容,在基岩地区和第四系松散沉积区应有很大的不同。在基岩地区应倜重于野外实地调查,包括填制工作区地质图、工作区岩石特征,岩石完整性调查和水井普测等;并通过充分的资料收集和必要的勘查手段,查明工作区地层、岩石、构造等地质条件,特别是划分构造带、构造影响带范围,进而判断换热孔钻遇地层的可钻性和换热能力,进行相关技术和经济分析及评价。     

豫西老君山花岗岩体SHRIMP锆石U-Pb年龄及其地球化学特征

豫西老君山花岗岩体位于北秦岭造山带中黑沟—栾川区域性断裂带的南侧。通过系统的野外调查,将岩体划分为3个主要的成岩期次:第1期为含小斑细中粒黑云母二长花岗岩,第2期为中斑中粒黑云母二长花岗岩,第3期为大斑中粗粒黑云母二长花岗岩,具有同心环带分布特征。在矿物组成和岩石地球化学成分特点上,这3期花岗岩体基本相似,均由钾长石、斜长石、黑云母和石英组成,但在岩石结构上有明显差异。岩石具有高硅(SiO2>70%)、高碱(NaO+K2O=8.28%～9.53%)、低钙(CaO=0.68%～2.42%)的特点。在微量元素上,Ba、Sr、Nb、Zr、Th、Rb含量较高,Co、Ni、Cr、V、Sc含量低。岩体属于I型花岗岩。第2期和第3期花岗岩的SHRIMP锆石U-Pb测年结果分别为(111±1)Ma(MSWD=0.41)和(108±1)Ma(MSWD=0.39),岩体形成于早白垩世,是中国东部晚中生代大规模岩浆作用晚期的产物。     

Ekman边界层动力学的理论研究

大气边界层及其与自由大气之间的相互作用具有明显的非线性特征,而这些特征是经典Ekman理论所不能描述的,因此,发展中等复杂程度(介于完全模式与经典Ekman模型之间)的大气边界层动力学模式,简称中间模式,对人们从理论上认识大气边界层动力学过程的非线性特征具有重要意义。本文对目前最具代表性的几个中间边界层模型:地转动量近似边界层模型、Ekman动量近似边界层模型以及弱非线性边界层模型进行了总结和分析,阐述了Ekman层主要动力学特征。通过分析上述各模型的理论框架,揭示了各模型的物理意义及其在描述Ekman边界层基本动力特征上的优点和局限性,并指出尽管在细节定量描述上有差异,但各中间模型对Ekman层动力学特征的定性描述具有很好的一致性。对于这些Ekman边界层近似理论模型的进一步应用问题,主要回顾和总结了利用上述模型探讨地形边界层结构、大气锋生过程、低层锋面结构和环流以及边界层日变化、低空急流形成等动力学问题的研究,并对这些研究所揭示的Ekman层动力学特征及其对自由大气低层运动的影响进行了分析,结果表明,这些Ekman边界层近似模型可以较好地揭示大气边界层动力学特征,在大气边界层动力学及其与自由大气相互作用的研究上具有重要价值。另外,还对目前Ekman边界层理论研究中存在的问题进行了一些分析,提出了有待进一步研究的科学问题。     

贵州省习水县暴雨特征及成因分析

【目的】在极端天气频发的气候背景下,有必要进一步分析习水县暴雨天气时空分布特征。【方法】利用1959—2022年贵州省习水国家基本气象站逐日降水资料、2010—2022年24个乡镇区域站日降水资料,运用统计学及空间插值等方法,对习水县的暴雨时空分布特征及成因进行分析。【结果】习水县暴雨多发生在习水河谷和赤水河谷的迎风坡及东部喇叭口地形区域,空间分布特征为北多南少;年区域性暴雨日数呈增长趋势;区域性暴雨月变化呈“单峰”型分布特征,主要出现在5—9月,占比94%;区域性大暴雨日数月分布呈“双峰”型分布,峰值在6月、8月。习水县暴雨具有明显日变化特征,夜雨特征明显,大暴雨夜雨占比81.1%;区域性暴雨天气过程主要降水时段集中在19时—次日06时,占比76.9%。习水从春季至秋季都有暴雨出现,暴雨日数频次大值区自西向东移动,夏季暴雨出现最多,占比69%。将造成区域性暴雨天气的影响系统分为低涡切变型、冷锋低槽型、梅雨锋型、台风外围型等4种类型。低涡切变型产生暴雨最多,占比77.3%。【结论】习水县暴雨空间分布呈北多南少,区域性暴雨主要出现在5—9月,夜雨特征明显,该研究成果可为更好地开展习水县暴雨灾害性天气预报及气象服务工作提供参考。     

Landscape Dynamics and Driving Factors in Da＇an County of Jilin Province in Northeast China During 1956-2000

The landscape pattern of Da＇an County, Northeast China has undergone significant changes since the 1950s as a result of climatic change and human activities. The aim of this paper is to quantitatively study landscape pattern and its spatial dynamics of Da＇an County at the landscape level over the nearly 50-year span. Patch dynamics were examined according to land use and land cover change processes built from a series of images, as well as topographic maps, and temporal patterns built from landscape pattern metrics. The transition matrix of landscape patch types and changes of various landscape metrics were applied. The results showed that, from 1956 to 2000, the landscape within the study area had undertaken a complicated evolution in landscape structure and composition. The outstanding characteristic is that saline-alkali land increased and grassland decreased. As some smaller patches amalgamated, the heterogeneity of patch decreased. All those changes were the synthetic result of both climatic and anthropogenic influences, but the predominant factor was different in different parts. In the southern part of the study area, the landscape pattern changes resulted from the modification of climate obviously, while in the northern part, the landscape pattern changes were mainly caused by human activities, such as the conversion between farmland and saline-alkali land. This phenomenon showed that human activities played more important role in the north than in the south of Da＇an County.     

Study on the Global Carbon Assimilation System Based on Multisource Remote Sensing Data

The Paris agreement signed in April, 2016 aims to balance global anthropogenic carbon emissions and terrestrial carbon sinks by the middle of the 21^st century. To fulfill this goal, it is necessary to calculate carbon fluxes of different regions reliably. The global carbon assimilation system is an effective technique for achieving this goal. The Ministry of Science and Technology of China supports the project entitled as study on the global carbon assimilation system based on multisource remote sensing data through the national key research and development programs for global change and adaptation during the thirteen-five period. This project will develop synergic inversion techniques for retrieving key parameters of biological and atmospheric cycles and for assimilating multisource remote sensing and ground based data. Then, the high resolution global carbon assimilation system coupled with an ecological model will be constructed. This system is able to assimilate jointly multisource observation data and to optimize key model parameters, photosynthesis and respiration carbon fluxes of global terrestrial ecosystems, and anthropogenic carbon emission fluxes of key regions. This system will be used to study quantitatively the spatial and temporal patterns of carbon fluxes of global terrestrial ecosystems and anthropogenic carbon emission fluxes of key regions and to identify the mechanisms driving the global terrestrial carbon sinks and sources. The outputs of this study will be helpful for the fulfillment of the key research and development programs for global change and adaptation and provide valuable data and technical support for the decision-making in China.