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11.
Anthropogenic activities have increased nitrogen (N) deposition in terrestrial ecosystems, which directly and indirectly affects soil biogeochemical processes, including soil respiration. However, the effects of the increases in N availability on soil respiration are not fully understood. In this study, soil respiration was measured using an infrared gas analyzer system with soil chambers under four N treatments (0, 5, 15, and 30 g N m-2 year-1 as control, low N (LN), moderate N (MN), and high N (HN), respectively) in camphor tree and slash pine forests in subtropical China. Results showed that soil respiration rates decreased by 37% in the camphor tree forest and 27% in the slash pine forest on average on an annual base, respectively, in the N-fertilized treatments when compared with the control. No significant differences were found in the soil respiration rate among the LN, MN, and HN treatments in both forest types as these fertilized plots reached an adequate N content zone. In addition, soil microbial biomass carbon (C) content and fine root biomass declined in N-treated plots compared to the control. Our results indicated that elevated N deposition might alter the tree growth pattern, C partitioning, and microbial activity, which further affect soil C sequestration by reducing soil respiration in subtropical forests of China. 相似文献
12.
[目的]研究低聚木糖对小鼠肠道菌群及润肠通便的影响。[方法]以BALB/c小鼠为试验对象,在连续给予高剂量(1.0g/kg.bw)、低剂量(0.5 g/kg.bw)的低聚木糖14 d后,测定小鼠粪便中双歧杆菌、乳杆菌、肠杆菌、肠球菌的含量;在连续给予高、低剂量的低聚木糖21 d后,以复方地芬诺酯建立小鼠便秘模型,测定给予低聚木糖后便秘小鼠的排首黑便时间、6 h内黑便重量及小肠推进率。[结果]与对照组相比,连续给予低聚木糖14 d后,低、高剂量组小鼠粪便内乳杆菌、双歧杆菌及B/E值均显著增加(P<0.05)。与灌服前相比,对照组肠球菌、乳杆菌显著增加(P<0.05);低、高剂量组肠杆菌显著减少(P<0.05),乳杆菌、双歧杆菌及B/E值显著增加。与模型对照组相比,连续给予低聚木糖21 d后,低、高剂量组的首粒排黑便时间显著缩短(P<0.05),排黑便总量显著增加(P<0.05),小肠推进率显著提高(P<0.01)。[结论]低聚木糖具有改善小鼠胃肠道菌群及润肠通便的功效。 相似文献
13.
14.
Dyeing and fastness properties of natural dyes extracted from eucalyptus leaves using padding techniques 总被引:1,自引:0,他引:1
A natural dye extracted from eucalyptus leaves was applied to a silk and wool fabric by the use of two padding techniques,
namely the pad-batch and pad-dry techniques under different conditions. Silk and wool fabrics dyed in a solution composed
of eucalyptus extract from leaves showed a shade of pale yellow to brown. The exception was when the fabric was dyed with
ferrous mordant, resulting in a shade of dark grayish-brown. The fastness properties ranged from good to excellent, while
light fastness was fair to good. 相似文献
15.
北京市各区县不透水面动态变化特征研究 总被引:1,自引:0,他引:1
利用多期Landsat MSS/TM数据对1992~1999、1999 ~ 2007和2007 ~ 2011年3个时段的北京市9个有代表性区县的不透水面变化特征进行分析.结果表明:经过近20年的发展,北京市各区县因为各种历史原因和所处的位置不同,向不透水面转化的地类存在着区位差异和动态特征.就面积而言:新增不透水面主要集中在发展新区的昌平、通州和顺义,其在各时期新增不透水面总和及增长率均远远超过拓展区的海淀、朝阳、丰台和石景山.早期各区县不透水面增加面积和速度均比较小,中期则大大增加,后期增加速度都有所放缓.不透水面比例显示:拓展区各区县的不透水面占各地类的比例从一开始(1992年)与耕地、绿地不相上下到后来逐渐占优(2007年),再到全部超过50%(2011年),占绝对优势,表明其用地结构却发生了质的变化,农业功能已很小.新区各区县不透水面比例虽然各时期均不断上升,但始终以耕地和绿地为主要用地类型.从不透水面来源看:1992 ~ 1999年,发展新区各区县是以耕地为不透水面主要来源;拓展区各区县则是以绿地和耕地转化为主要方式.1999 ~ 2007年,各区县由耕地转化所占比例都有所上升.2007~2011年,只有新区的区县仍以耕地为不透水面增加的主要来源,耕地和绿地转化为不透水面的趋势有所控制,城市生态环境保护政策的效果初步显现. 相似文献
16.
《Agricultural Water Management》1999,42(2):189-204
Data is presented comparing infiltration of irrigation and rain water to potato crops planted in ridges and beds in East Anglia, UK. An automatic soil water station (ASWS) was used to monitor soil water content and potential in the two cultivation systems. The ASWS data indicated that most of the water bypassed the potatoes planted in ridges as irrigation water applied to the crop from a boom irrigator was shed off the ridges infiltrating in the furrows. This was due to the water repellent nature of the sandy soil and meant that the irrigation water bypassed the potatoes. A soil water deficit built up in the core of the ridge as the crop grew and was not replenished by irrigations. A second early potato crop planted in beds was more successful at capturing water as the flat bed increased water infiltration around the crop. This has major implications for cultivation practice, scab control and crop water management. Instruments measuring soil water potential, content, temperature and rainfall were connected to a data logger powered by a solar panel and proved a successful way of monitoring infiltration. Hourly data was collected so that a high temporal resolution data set could be constructed in order to increase conceptual understanding of hydrological processes at a scale appropriate to the crop. 相似文献
17.
《Pesticide biochemistry and physiology》1987,28(2):163-171
Uptake, movement, and metabolism of unformulated ioxynil and bromoxynil salts were investigated in Matricaria inodora and Viola arvensis. The morphology of these two species did not give rise to different spray retention and contact angles. After 7 days, uptake of [14C]ioxynil-Na reached 8.26% of applied 14C activity in M. inodora and 16.77% of that in V. arvensis compared with 1.54 and 3.83%, respectively, for [14C]bromoxynil-K. Over 98% of the 14C activity detected in the plant after 7 days remained in the treated leaves of V. arvensis following [14C]ioxynil-Na treatment. However, 8.7% of the 14C activity detected in [14C]ioxynil-Na-treated M. inodora was recovered from the apex and developing leaves reflecting a greater translocation. [14C]Bromoxynil-K was more mobile in both species and after 7 days 87.5 and 91.39% were detected in the treated leaves of M. inodora and V. arvensis, respectively. In both species the majority of translocated 14C activity was recovered from the apex and developing leaves. Up to 20% of the applied [14C]ioxynil-Na and [14C]bromoxynil-K was not detected within the treated plant. Extraction of treated plants revealed no detectable metabolic breakdown of ioxynil-Na to halogenated derivatives in either species. However, metabolic breakdown of bromoxynil-K was apparent in V. arvensis. No significant root exudation was detected when [14C]ioxynil-Na and [14C]bromoxynil-K were applied to hydroponically grown S. media and V. arvensis. Losses of 14C activity were due to herbicide volatility or degradation to volatile products on the leaf surface. 相似文献
18.
The beneficial effect of nature on patients with mental disorders is of particular importance. There has been an increase in mental illnesses in recent years, but research on the design of healing gardens for mental and behavioural disorders remains limited. This paper is part of a wider study that aims to investigate the effect of selected design elements of healing gardens on patients with mental disorders. This study examines the effect of seasonal colour change in plantings in the design of healing gardens on patients suffering from psychotic disorders by using a questionnaire survey and by recording and analysing human behaviour. Images depicting seasonal colour change in different plantings were viewed on a computer monitor by patients. Patients’ behaviour was studied using biosensors for eye-tracking, facial expression analysis and galvanic skin response. The results showed that differences in gender and age between participants did not affect their preferences. However, it appeared to be more difficult to positively affect the emotions of male participants compared to female participants. Seasonal colour change in a tree canopy created positive and intense emotions in the patients. Based on the results, the use of deciduous trees is proposed in the design of healing gardens for patients with psychotic disorders to create seasonal colour change. Further research is necessary to obtain more detailed design recommendations for landscape architects. 相似文献
19.
吕俊杰 《农业图书情报学刊》2015,27(12):90-92
图书馆是学生的第二课堂,图书馆存在的价值和意义就在于满足读者的需求,服务教学与科研。然而,图书馆焦虑严重阻碍了读者对于图书馆的使用,使图书馆无法发挥其应有的作用。本文从图书馆三要素馆舍、馆藏、馆员3方面分析可能引起图书馆焦虑的原因,并指出此三方面具体的改进措施,以期找出化解图书馆焦虑的方法和途径。 相似文献
20.
Ebrima S. Dem Beatriz Rodríguez-Labajos Martin Wiemers Jürgen Ott Norbert Hirneisen Jesus Victor Bustamante Marlynne Bustamante Josef Settele 《Paddy and Water Environment》2018,16(4):725-735
This study relies on the Flying Beauties Citizen Science project conducted in the Philippines to assess personal motivations and learning outcomes of volunteers who were involved in documenting butterflies and dragonflies in rice ecosystems. While evaluation of motivations of volunteers in Citizen Science is not new, at least in affluent western countries, little is done in investigating volunteers’ motivations and learning outcomes of Citizen Science projects in low-income countries. Using surveys, we collected data from volunteers that were analysed qualitatively and quantitatively. We adopted a two stages evaluation format—before and after volunteers finished the project exercise. We compared pre-motivations to motivations attained and changes in level of knowledge before and after the project ended. We use Spearman’s Rho, Kendall’s Tau—nonparametric tests to draw correlations between variables. The results showed that key determinants that drove people to volunteer in the project were (a) learning about species and (b) being part of scientific research and the principal learning outcome was improved awareness about ecosystem functions of the species. 相似文献