基于地理国情的深度学习分类容错性研究

地理国情监测获取的地表覆盖分类成果具有覆盖区域全、精细度高、时相新等优势,具有作为深度学习分类模型训练样本的能力和优势,能够大大减少样本获取的成本.但是,受数据源、时相以及采集标准等因素的影响,直接使用地表覆盖数据作为样本,往往与模型训练采用的影像存在一定的误差.研究采用深度学习语义分割算法,比较了人工标注样本以及不同...     

NO在两种圆柏属植物叶片抗冻过程中的信号功能研究

通过测定自然降温过程中抗氧化系统、膜脂过氧化、NO释放量、NO合成酶(NOS)和硝酸还原酶(NR)活性的季节变化,研究植物内源NO在圆柏属植物祁连圆柏(Sabina przewalskii)和圆柏(Sabina chinensis)叶抗冻过程中的信号功能.结果表明:随温度降低,过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸氧化酶(APX)活性和谷胱甘肽(GSH)、脯氨酸(Pro)、类胡罗卜素(Car)含量增加并在冬季达最大值,NO释放率、NOS和NR活性以及丙二醛(MDA)含量也显著增加并在9月和2月出现两峰值;两树种叶中的抗氧化酶活性和抗氧化剂含量都与平均温度和MDA含量负相关,而且NO的产生总是发生在抗氧化酶活性和抗氧化剂含量增加之前,表明抗氧化系统在清除氧自由基抑制膜脂过氧化提高抗冻性方面具有重要作用,NO作为信号分子可能激活了抗氧化系统诱导植物抗冻性.在抗冻过程中,祁连圆柏叶的NO释放率、NOS和NR活性、抗氧化酶活性以及抗氧化剂含量都高于圆柏,表明祁连圆柏具有较强的适应性策略.     

屏障效应对生物地球化学异常形成的影响及找矿有效指示植物的选择

采用光谱仪及透射电子显微镜对广西几个金属矿床的生物地球化学异常和植物细胞微观特征进行了研究,结果发现:生物地球化学异常对土壤地球化学异常有明显的物质性继承关系;生物地球化学异常的物质以金属聚集体(电子致高密度体物质)的形式沉淀在植物液胞中或细胞壁及膜边缘,其对植物的伤害可能只达到细胞或组织的水平.生物地球化学异常的形成...     

Effect of soil salinity on cold tolerance of mangrove Kandelia candel

Analysis of cold tolerance on mangrove Kandelia candel leaf growing in different soil salinity along Jiulong River Estuary in South China showed that the cold tolerance decreased as the increase of soil salinity. The lethal temperatures of K. candel leaf were-10.4,-9.9 and-8.6℃ in Liaodong, Baijiao and Aotou, respectively. Under 1-2℃ cold stress treatment on detached leaves of K. candel, their caloric value gradually decreased, while electrolyte leakage gradually increased. The leaf＇s caloric value and electrolyte leakage in Aotou with higher soil salinity varied more largely than those in Liaodong with lower soil salinity. In K. candel leaf, total water content lowered a little, bound water content rose significantly and free water content dropped significantly with duration of cold stress. At the same time, reduction sugar, soluble sugar and starch content gradually decreased and sucrose content gradually increased. Bound water, free water and sucrose content in K. candel leaf from Aotou with higher soil salinity changed more slowly than those from Liaodong with lower soil salinity, but reduction sugar, soluble sugar and starch content in K. candel leaf from Aotou had faster variations than those from Liaodong. These data indicated that soil salinity can reduce cold tolerance of K.candel leaf by increasing negative effect of salt ions in cell membrane, inhibiting variations of water content, and aggravating consumption of material and energy.     

Uncertainties in global warming science and near-term emission policies

Abstract

It is argued here that stringent, early emission reductions are necessary in order to minimize ‘dangerous anthropogenic interference in the climate system’ (DAI), the stated Objective of Article 2 of the UNFCCC (United Nations Framework Convention on Climate Change). Given probability distribution functions (pdfs) for climate sensitivity and the temperature threshold for harm consistent with currently available evidence, and accepting a 10% risk of unacceptable damage as the threshold for ‘danger’, it is not possible to avoid DAI. Having adopted a precautionary approach in setting emission trajectories, the possibility arises that future resolution of uncertainties concerning climate sensitivity and the harm threshold may show the climate sensitivity to be low (1–2 K) and the harm threshold high (2 K rather than 1 K). Using a simple coupled climate-carbon cycle model, it is shown that if the climate sensitivity were to be definitively determined to be 2 K in 2020, then the emission reductions achieved by that time and planned for the next two decades are still fully needed. Only if climate sensitivity is very low (1 K) and the harm threshold is high (2 K) would the emissions achieved by 2020 not have been fully necessary. However, this would still lead to changes in ocean chemistry that are likely to be highly detrimental to marine life. Thus, when the full spectrum of impacts is considered, there is no plausible set of assumptions under which stringent near-term emission reductions are rendered unnecessary.     

Fe^2＋浓度对Acidithiobacillus ferrooxidans耐铜性的影响

嗜酸性氧化亚铁硫杆菌（Acidithiobacillus ferrooxidans）是铜矿生物冶金中应用最广泛的微生物之一。但在冶金过程中淋滤出来的Cu2＋等重金属逐渐积累,达到一定的浓度后就会抑制A.ferrooxidans的生长,从而降低冶金的效率。本文着重研究了Fe2＋初始浓度对A.ferrooxidans耐铜性的影响。实验中ρ（Cu2＋）变化范围为0～5.0 g/L。结果表明,当ρ0（Fe2＋）为6.7 g/L时,A.ferrooxidans仅在Cu2＋为0～0.4 g/L的体系中能显著地氧化Fe2＋进行生长;当Cu2＋≥0.5 g/L时,A.ferrooxidans生长完全受到抑制。将ρ0（Fe2＋）增加到8.9 g/L,A.ferroox-idans在0.5、1.0、2.0和3.0 g/L Cu2＋的培养基中也能明显氧化Fe2＋,并最终将其完全氧化,Cu2＋对A.ferrooxidans生长抑制作用仅出现在4.0和5.0 g/L Cu2＋的体系中。因此提高体系中亚铁离子的浓度能提高菌体对Cu2＋的耐受力。研究结果对铜矿的生物冶金具有重要意义。     

条纹锯鮨对盐度胁迫的耐受力及淡水胁迫恢复的初步研究

本文研究了条纹锯鮨(Centropristis striata)鱼种对低盐度胁迫的耐受力,以及淡水胁迫后最适恢复时间范围.实验结果表明:规格(20.32±9.67)cm的鱼种在0盐度的半致死时间为(1.63±0.23)h,规格(10.20±0.63)cm的鱼种在0盐度的半致死时间为(0.77±0.23)h.同时,2种规...     

Effect of soil salinity on cold tolerance of mangrove Kandelia candel

Analysis of cold tolerance on mangroveKandelia candel leaf growing in different soil salinity along Jiulong River Estuary in South China showed that the cold tolerance decreased as the increase of soil salinity. The lethal temperatures ofK. candel leaf were −10.4, −9.9 and −8.6 °C in Liaodong, Baijiao and Aotou, respectively. Under 1–2°C cold stress treatment on detached leaves ofK. candel, their caloric value gradually decreased, while electrolyte leakage gradually increased. The leaf's caloric value and electrolyte leakage in Aotou with higher soil salinity varied more largely than those in Liaodong with lower soil salinity. InK. candel leaf, total water content lowered a little, bound water content rose significantly and free water content dropped significantly with duration of cold stress. At the same time, reduction sugar, soluble sugar and starch content gradually decreased and sucrose content gradually increased. Bound water, free water and sucrose content inK. candel leaf from Aotou with higher soil salinity changed more slowly than those from Liaodong with lower soil salinity, but reduction sugar, soluble sugar and starch content inK. candel leaf from Aotou had faster variations than those from Liaodong. These data indicated that soil salinity can reduce cold tolerance ofK. candel leaf by increasing negative effect of salt ions in cell membrane, inhibiting variations of water content, and aggravating consumption of material and energy. Supported by the Found for Outstanding Young Teacher, the Ministry of Education, China.     

Relationship of minimum winter temperature and temperature seasonality to the northern range limit and species richness of trees in North America

Biologists have considered both winter coldness and temperature seasonality as major determinants of the northern limits of plants and animals in the Northern Hemisphere,which in turn drive the well-known latitudinal diversity gradient.However,few studies have tested which of the two climate variables is the primary determinant.In this study,we assess whether winter coldness or temperature seasonality is more strongly associated with the northern latitudinal limits of tree species and with tree species richness in North Amedca.Tree species were recorded in each of 1198 quadrats of 110 km × 110 km in North America.We used correlation and regression analyses to assess the relationship of the latitude of the northern boundary of each species,and of species richness per quadrat,with winter coldness and temperature seasonality.Species richness was analyzed within 38 longitudinal,i.e.,north-south,bands (each being ＞1100 km long and 110 km wide).The latitudes of the north-ern range limits of tree species were three times better correlated with minimum temperatures at those latitudes than with temperature seasonality.On average,minimum temperature and temperature seasonality together explained 81.5％ of the variation in the northern range limits of the tree species examined,and minimum temperature uniquely explained six-fold (33.7％versus 5.8％) more of this variation than did temperature seasonality.Correlations of tree species richness with minimum temperatures were stronger than correlations with tempera-ture seasonality for most of the longitudinal bands analyzed.Compared to temperature sea-sonality,winter coldness is more strongly associated with species distributions at high lati-tudes,and is likely a more important driver of the latitudinal diversity gradient.     

天津厚蟹对盐度和温度的耐受性

研究了天津厚蟹Helice tientsinensis对盐度和温度的耐受性。天津厚蟹对盐度的耐受能力极强,在温度9~34℃盐度为0的淡水介质中均能存活96h以上;在10℃、20℃及30℃的高渗介质中暴露96h后,天津厚蟹全部存活的盐度分别是65、56和50,全部死亡的盐度分别为83、74和68。天津厚蟹对低温的耐受力较强,在0、30和50盐度水平下,耐受低温的能力差别较大,能耐受96h的最低温度分别是9℃、2℃和6℃。天津厚蟹对高温也有较强的耐受能力,在0、30和50盐度水平下,分别在34℃、36℃和35℃下能耐受96h;盐度50温度38℃时,在开始的24h内无死亡,但48h后死亡率急剧上升,同样规律也出现在30和0溶液中,前者温度是39℃,后者为35℃。研究结果还表明盐度和温度的交互效应显著,二者的交互作用对天津厚蟹的存活亦有显著性影响(P0.05),温度升高(从10℃到20℃再到30℃)致使其耐盐能力显著下降,而盐度的剧烈变化(从30到50或从30到0)也致使其耐温能力显著下降。