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1. chinaXiv:201801.00128 [pdf]

Habitat, occurrence and conservation status of the Saharo-Macaronesian and Southern-Mediterranean element Fagonia cretica L. (Zygophyllaceae) in Italy

Giovanni SPAMPINATO; Carmelo M MUSARELLA; Ana CANO-ORTIZ; Giuseppe SIGNORINO
分类: 生物学 >> 植物学

Fagonia cretica L. is an important component of Mediterranean dry grasslands and a rare and isolated species of Italian flora. In this study, an assessment is presented on the distribution, habitat, and conservation status of F. cretica in Italy. The results of field investigation and herbarium analysis show that this species grows in a small area within the southern Calabria region characterized by a warmest and driest Mediterranean climate on the Italian peninsula. F. cretica is a semi-desert plant species growing in Italy in only one peripheral and isolated population at the northern limit of its distribution. Plant community analysis, using the phytosociological method, shows that F. cretica grows in wintergreen perennial dry grasslands dominated by Lygeum spartum and Hyparrhenia hirta. F. cretica plant communities are located in thermo-xeric habits such as south-, southeast- and east-facing slopes on clays and sandy clays in southern Calabria. The population of F. cretica is fragmented in six neighbouring localities, with two of which belonging to a Site of Community Importance (SCI). The conservation status of F. cretica population is not very good, and is defined as “Critically Endangered” in accordance with IUCN criteria. There are many threats affecting the F. cretica population in Italy, primarily the changes in land uses due to urban expansion and reforestation with exotic plants. The southern end of the Italian peninsula hosts other plants from thermo-xeric habits that do not adapt to the current local climate. This territory can be considered as a microrefugia for plants currently distributed in the arid territory of the southern Mediterranean. These results contribute to the discussion of some conservation measures, and the possibility of establishing a micro-reserve. For all these reasons, we propose to include F. cretica in the lists of protected plant species at regional (Calabria) and country (Italy) scales in Italy.

提交时间: 2018-01-10 来自合作期刊:《Journal of Arid Land》 点击量7下载量5 评论 0

2. chinaXiv:201801.00129 [pdf]

Utilizing a new soil effective temperature scheme and archived satellite microwave brightness temperature data to estimate surface soil moisture in the Nagqu region, Tibetan Plateau of China

TIAN Hui; Mudassar IQBAL
分类: 农、林、牧、渔 >> 土壤学

Since the early 2000s, many satellite passive microwave brightness temperature (BT) archives, such as the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) BTs, have become the useful resources for assessing the changes in the surface and deep soil moistures over both arid and semi-arid regions. In this study, we used a new soil effective temperature (Teff) scheme and the archived AMSR-E BTs to estimate surface soil moisture (SM) over the Nagqu region in the central Tibetan Plateau, China. The surface and deep soil temperatures required for the calculation of regional-scale Teff were obtained from outputs of the Community Land Model version 4.5 (CLM4.5). In situ SM measurements at the CEOP-CAMP/Tibet (Coordinated Enhanced Observing Period Asia-Australia Monsoon Project on the Tibetan Plateau) experimental sites were used to validate the AMSR-E-based SM estimations at regional and single-site scales. Furthermore, the spatial distribution of monthly mean surface SM over the Nagqu region was obtained from 16 daytime AMSR-E BT observations in July 2004 over the Nagqu region. Results revealed that the AMSR-E-based surface SM estimations agreed well with the in situ-based surface SM measurements, with the root mean square error (RMSE) ranging from 0.042 to 0.066 m3/m3 and the coefficient of determination (R2) ranging from 0.71 to 0.92 during the nighttime and daytime. The regional surface soil water state map showed a clear spatial pattern related to the terrain. It indicated that the lower surface SM values occurred in the mountainous areas of the northern, mid-western and southeastern parts of Nagqu region, while the higher surface SM values appeared in the low elevation areas such as the Tongtian River Basin, Namco Lake and bog meadows in the central part of Nagqu region. Our analysis also showed that the new Teff scheme does not require special fitting parameters or additional assumptions, which simplifies the data requirements for regional-scale applications. This scheme combined with the archived satellite passive microwave BT observations can be used to estimate the historical surface SM for hydrological process studies over the Tibetan Plateau regions.

提交时间: 2018-01-10 来自合作期刊:《Journal of Arid Land》 点击量7下载量5 评论 0

3. chinaXiv:201801.00130 [pdf]

Influences of calcium silicate on chemical forms and subcellular distribution of cadmium in Amaranthus hypochondriacus L.

Lu, Huanping; Li, Zhian; Wu, Jingtao; Shen, Yongd; Li, Yingwen; Zou, Bi; Tang, Yetao; Zhuang, Ping
分类: 生物学 >> 植物学

A pot experiment was conducted to investigate the effects of calcium silicate (CS) on the subcellular distribution and chemical forms of cadmium (Cd) in grain amaranths (Amaranthus hypochondriacus L. Cv. 'K112') grown in a Cd contaminated soil. Results showed that the dry weight and the photosynthetic pigments contents in grain amaranths increased significantly with the increasing doses of CS treatments, with the highest value found for the treatment of CS3 (1.65 g/kg). Compared with the control, application of CS4 (3.31 g/kg) significantly reduced Cd concentrations in the roots, stems and leaves of grain amaranths by 68%, 87% and 89%, respectively. At subcellular level, CS treatment resulted in redistribution of Cd, higher percentages of Cd in the chloroplast and soluble fractions in leaves of grain amaranths were found, while lower proportions of Cd were located at the cell wall of the leaves. The application of CS enhanced the proportions of pectate and protein integrated forms of Cd and decreased the percentages of water soluble Cd potentially associated with toxicity in grain amaranths. Changes of free Cd ions into inactive forms sequestered in subcellular compartments may indicate an important mechanism of CS for alleviating Cd toxicity and accumulation in plants.

提交时间: 2018-01-10 点击量8下载量6 评论 0

4. chinaXiv:201801.00131 [pdf]

Assessment of influences of cooking on cadmium and arsenic bioaccessibility in rice using in vitro physiologically based extraction test

Zhuang, Ping; Zhang, Chaosheng; Li, Yingwen; Zou, Bi; Mo, Hui; Wu, Kejun; Wu, Jingtao; Li, Zhian
分类: 生物学 >> 生态学

The health risks associated with the consumption of rice may decrease if consumers use cooking practices which can reduce the concentrations of metal(loid)s and their bioaccessibility. The effects of cooking on the bioaccessibility of Cd and As in three contamination levels of rice were studied. The results indicated that cooking reduced bioaccessibility of Cd and As in rice. Cooking resulted in a significant increase in Cd and As concentrations in the residual fraction. Low volume cooking rice to dryness remove total Cd by about 10% for rice A and B, while middle or high volume water had no effect on Cd bioaccessibility in all rice types. In contrast, low volume cooking did not remove As, but a significant decrease was observed when cooking with middle or high volume water. This study provides information for a better understanding of more realistic estimation of metal(loid)s exposure from rice and the possible health risks.

提交时间: 2018-01-10 点击量7下载量5 评论 0

5. chinaXiv:201801.00132 [pdf]

热力学与传热学的共性理论基础——可逆与不可逆过程普适的有效能方程

陈则韶; 李川; 王刚
分类: 动力与电气工程 >> 工程热物理学

回顾总结了热力学与传热学共性理论基础研究的系列成果,从正视热力学第二定律、“熵产”理论在实际应用中存在的问题入手,以势能理论为依据,用相对环境平衡态的势能为基准态势能定义了能量中的有效能和无效能。这种定义具有与“?”相同的性质,又能从定义式直接写出有效能函数的表达式。继而利用热力学第一定律方程,推导出了普适的有效能方程、有效能率方程,并与熵方程、火积耗散方程和?方程进行了比较。前者方程各项都只与状态有关,都能独立计算出来,而后三个方程都有一项与不可逆过程有关的补缺项。把有效能率方程应用于传热过程,导出了传热效率的表达式;应用于实际热机系统,导出了传热与热力耦合系统的输出功率、输入热流率、效率、换热器传热系数以及热源参数之间的关系,并举例应用于系统优化设计。本文构建的热力学和传热学共性理论,为热机与换热器耦合进行热力系统综合分析和协调优化提供了理论基础。

提交时间: 2018-01-10 来自合作期刊:《工程热物理学报》 点击量5下载量5 评论 0

7. chinaXiv:201801.00134 [pdf]

深圳近海表层浮游细菌分布特征及其环境影响因素

李建洋,赵月,谢宁栋,王雅琼,冷科明,陈子熙,汪光义
分类: 生物学 >> 生态学

于2015年3月、5月、8月和10月在深圳市近岸海域(珠江口、深圳湾和大亚湾)采集表层水样,利用流式细胞仪测定总浮游细菌、高DNA含量亚群细菌(HNA)、低DNA含量亚群细菌(LNA)的丰度,分析它们的时空分布特点,阐释环境因子对浮游细菌时空分布格局的影响。结果表明,珠江口、深圳湾和大亚湾海域表层浮游细菌的平均丰度依次降低,分别为3.82×106个/mL、7.67×106个/mL和3.38×106个/mL。珠江口海域浮游细菌丰度由远岸到近岸递增,深圳湾海域湾内各站位浮游细菌丰度差异较小,大亚湾海域浮游细菌丰度空间差异不显著(P > 0.05)。浮游细菌丰度时间差异主要受温度影响,空间差异主要受营养盐和叶绿素a影响。HNA亚群丰度时空差异性比LNA亚群的大,HNA亚群受温度影响显著(P < 0.01),而LNA亚群与温度相关性不显著(P > 0.05)。环境对HNA和LNA亚群丰度的影响有许多相似之处,但两者对某些环境因子有着不同的响应,说明它们在近海表层生态系统中可能扮演着部分重叠但略有不同的角色。

提交时间: 2018-01-10 来自合作期刊:《生态学报》 点击量9下载量7 评论 0

8. chinaXiv:201801.00135 [pdf]

基于MaxEnt的西藏飞蝗在中国的适生区预测

王茹琳,李庆,封传红,石朝鹏
分类: 生物学 >> 生态学

西藏飞蝗是青藏高原本地特有物种,为青稞和牧草的重要害虫,近年来危害范围有扩大蔓延趋势。研究并明确西藏飞蝗在中国的适生区域,对制定该虫的早期监测、预警及控制措施意义重大。近年来最大熵理论在物种适生研究领域得到广泛应用,基于西藏飞蝗的分布信息和环境变量,采用MaxEnt生态位模型和ArcGIS对其在中国的潜在分布区进行预测,用ROC曲线检测模型精度、刀切法(jackknife test)筛选主导环境变量及其适宜值。两次模拟的AUC值分别为0.996和0.993,预测结果与实际拟合度很高。西藏飞蝗在中国的高适生区主要位于四川的甘孜州,西藏的昌都地区、林芝地区、山南地区及拉萨市,中适生区则以高适生区为中心向外扩散,集中在青藏高原东部地区。海拔、8月份平均雨量、1月份平均雨量、等温性、12-2月份的平均温度是影响西藏飞蝗潜在分布的主要环境变量。

提交时间: 2018-01-10 来自合作期刊:《生态学报》 点击量10下载量8 评论 0

9. chinaXiv:201801.00136 [pdf]

UV-B长期胁迫对麦长管蚜子代种群动态的影响

车文艳,梁霞,王萍,赵惠燕
分类: 生物学 >> 生态学

为了探明UV-B长期辐射亲代麦长管蚜Sitobion avenae Fabricius后对其子代种群动态的影响。采用特定年龄生命表方法,设置不同强度(0,0.50,0.70 mW/cm2)UV-B连续多代处理麦长管蚜成虫,统计麦长管蚜分别经历UV-B辐射一代,六代,十一代,十五代后其子代麦长管蚜存活率和繁殖力、繁殖参数、种群参数的变化。结果表明:(1)经UV-B处理亲代麦长管蚜后,其子代种群的内禀增长率r与周限增长率λ在低强度处理组各世代之间无显著差异,在高强度处理组各世代之间呈先上升后下降的趋势。(2)处理组麦长管蚜种群繁殖力F、净增殖率R0、平均世代周期T、产卵天数和成蚜寿命均在G7代达到最大值,且与对照组无显著差异。(3)亲代麦长管蚜经UV-B胁迫处理后对子代种群的存活率影响显著。研究结论:亲代麦长管蚜经过不同代数的UV-B胁迫,可显著影响子代的生长发育与繁殖,且对处于不同世代的子代生态学指标产生不同影响。研究的创新点在于探究亲代麦长管蚜经历紫外胁迫后对其子代生长、发育与繁殖的影响,为逆境胁迫下蚜虫的生态遗传与进化机理提供理论依据。

提交时间: 2018-01-10 来自合作期刊:《生态学报》 点击量8下载量6 评论 0

10. chinaXiv:201801.00137 [pdf]

基于植物区系的雷州半岛天然林群落树种特征研究

韩维栋,黄剑坚
分类: 生物学 >> 生态学

传统涉及植物区系和重要值的研究思路通常先分析该地区的植物区系组成,然后再分析该区域某个区系中某个优势种的重要值。该种思路存在未能完全同时反映不同区系不同植物物种参与群落构建和其在群落中的地位等缺陷。为了解决上述问题,构建物种群落指数,以雷州半岛天然季雨林的木本植物为对象开展研究。基于雷州半岛8个区域的80个20 m×20 m固定样地的实测数据,通过植物区系+重要值的方式构建物种群落指数开展研究。(1)湛江云脚村群落、湛江湖光岩、雷州鹰峰岭、雷州足荣村、徐闻双洋村、廉江高桥和廉江谢鞋山皆以热带区系分布为主导,数值皆大于0.8以上。廉江根竹嶂地理位置特殊,以9区系东亚和北美洲间断分布为主,数值接近0.5。(2)第2区系树种在雷州半岛群落树种组成和构建中处于优势地位,最高值为0.4261,朴树和鹅掌柴为优势种;第3区系树种和第6区系树种处于劣势地位;第4区系树种处于优势地位,最高值为0.3339,橄榄为优势种;第5区系树种处于优势地位,最高为0.3787,阴香和樟树为优势种;第7区系树种在雷州半岛地区群落内分布较为均衡,普遍适应各个样地。本研究表明,雷州半岛地区带有明显的热带性区系特征;物种群落指数能够较好的体现雷州半岛样地各个区系树种在植物群落组成的特征。

提交时间: 2018-01-10 来自合作期刊:《生态学报》 点击量2下载量2 评论 0

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