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微博舆论的自净化力与和谐社会的构建 被引量:2
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作者 唐爱芳 《经济研究导刊》 2012年第5期264-265,共2页
微博作为自媒体新典型代表,不仅成为草根舆论监督及时便捷的平台,而且成为迅速制止流言传播的最有效渠道,具备意想不到的"自净化力"。但是,微博舆论是一把"双刃剑",它会成为谣言滋生地,会被某些公众人物操控话语权... 微博作为自媒体新典型代表,不仅成为草根舆论监督及时便捷的平台,而且成为迅速制止流言传播的最有效渠道,具备意想不到的"自净化力"。但是,微博舆论是一把"双刃剑",它会成为谣言滋生地,会被某些公众人物操控话语权,易形成"多数暴政",造成"群体极化"现象。因此,推进网络文明建设,加快微博立法,引导、培养"意见领袖"等"新意见阶层",掌握"第一时间"法则等对于微博舆论的引导策略就显得尤为重要。 展开更多
关键词 微博 净化力 和谐社会
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低温下净化力仍很高的汽车排气用催化剂
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《现代化工》 CAS CSCD 北大核心 2004年第4期70-70,共1页
关键词 催化剂 汽车 尾气净化 低温 净化力
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冬、夏两季组合湿地系统的净化力对比分析 被引量:8
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作者 陈涛 于鲁冀 +1 位作者 柏义生 范鹏宇 《环境工程》 CAS CSCD 北大核心 2018年第5期16-20,共5页
建立了用以处理污染河流水体的"表面流湿地-垂直流湿地-稳定塘"组合人工湿地系统,日处理水量为7万t,水力停留时间为24 h,对比分析了组合人工湿地系统冬、夏两季的水体净化力。结果表明:冬、夏两季组合湿地系统出水中COD、氨氮... 建立了用以处理污染河流水体的"表面流湿地-垂直流湿地-稳定塘"组合人工湿地系统,日处理水量为7万t,水力停留时间为24 h,对比分析了组合人工湿地系统冬、夏两季的水体净化力。结果表明:冬、夏两季组合湿地系统出水中COD、氨氮、TP、TN月均值可达GB 3838—2002《地表水环境质量标准》IV类标准,不同单元之间净化力差异显著,垂直流湿地贡献率最大;组合湿地系统对COD和氨氮去除率存在显著的季节性差异,冬季对COD和氨氮的平均去除率分别为25.97%和30.26%,显著低于夏季的43.07%和54.20%;组合湿地系统对氮、磷去除效果季节性差异不显著,冬季对TN和TP的平均去除率分别为48.35%和59.26%,而夏季组合湿地系统对TN和TP的平均去除率分别为48.87%和55.26%。要克服冬季对组合湿地系统净化力的影响,需考虑增强垂直流湿地单元的吸附过滤功能和提高湿地系统冬季的生物活性。 展开更多
关键词 污染河流水体 组合人工湿地 垂直流湿地 季节效应 净化力
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中国共产党政治文化领导力的意涵与提升
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作者 雷青松 《领导科学》 北大核心 2021年第22期16-19,共4页
中国共产党的党内政治文化是党的领导力的价值密码,其内含的政治信仰、政治价值、政治情感等汇成了党的领导力基础。百年大党历经革命、建设、改革不同历史时期形成的优良的党内政治文化,化为党的领导力实践向度的重要表征,可以概括为... 中国共产党的党内政治文化是党的领导力的价值密码,其内含的政治信仰、政治价值、政治情感等汇成了党的领导力基础。百年大党历经革命、建设、改革不同历史时期形成的优良的党内政治文化,化为党的领导力实践向度的重要表征,可以概括为引领力、塑造力、传播力、净化力的合力。若从政党治理战略视角去思考,要想全面提升党的领导力,需要以上述“四力”为基点,以政治文化自信锻造党的领导力,以政治文化自硬塑强党的领导力,以政治文化自觉淬炼党的领导力。 展开更多
关键词 中国共产党 政治文化 领导 引领 塑造 传播 净化力
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Spatio-temporal distribution of net primary productivity along the northeast China transect and its response to climatic change 被引量:9
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作者 朱文泉 潘耀忠 +1 位作者 刘鑫 王爱玲 《Journal of Forestry Research》 SCIE CAS CSCD 2006年第2期93-98,共6页
An improved Carnegie Ames Stanford Approach model (CASA model) was used to estimate the net primary productivity (NPP) of the Northeast China Transect (NECT) every month from 1982 to 2000. The spatial-temporal d... An improved Carnegie Ames Stanford Approach model (CASA model) was used to estimate the net primary productivity (NPP) of the Northeast China Transect (NECT) every month from 1982 to 2000. The spatial-temporal distribution of NPP along NECT and its response to climatic change were also analyzed. Results showed that the change tendency of NPP spatial distribution in NECT is quite similar to that of precipitation and their spatial correlation coefficient is up to 0.84 (P 〈 0.01). The inter-annual variation of NPP in NECT is mainly affected by the change of the aestival NPP every year, which accounts for 67.6% of the inter-annual increase in NPP and their spatial correlation coefficient is 0.95 (P 〈 0.01). The NPP in NECT is mainly cumulated between May and September, which accounts for 89.8% of the annual NPP. The NPP in summer (June to August) accounts for 65.9% of the annual NPP and is the lowest in winter. Recent climate changes have enhanced plant growth in NECT. The mean NPP increased 14.3% from 1980s to 1990s. The inter-annual linear trend of NPP is 4.6 gC·m^-2·a^-1, and the relative trend is 1.17%, which owns mainly to the increasing temperature. 展开更多
关键词 China Transect Remote sensing Net primary productivity (NPP) Climatic change Spatio-temporal distribution
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Seasonal Dynamics of Terrestrial Net Primary Production in Response to Climate Changes in China 被引量:32
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作者 朴世龙 方精云 陈安平 《Acta Botanica Sinica》 CSCD 2003年第3期269-275,共7页
Study on seasonal responses of terrestrial net primary production (NPP) to climate changes is to help understand feedback between climate systems and terrestrial ecosystems and mechanisms of increased NPP in the north... Study on seasonal responses of terrestrial net primary production (NPP) to climate changes is to help understand feedback between climate systems and terrestrial ecosystems and mechanisms of increased NPP in the northern middle and high latitudes. In this study, time series dataset of normalized difference vegetation index (NDVI) and corresponding ground-based information on vegetation, climate, soil, and solar radiation, together with an ecological process model, were used to explore the seasonal trends of terrestrial NPP and their geographical differences in China from 1982 to 1999. As the results,. seasonal total NPP in China showed a significant increase for all four seasons (spring, summer, autumn and winter) during the past 18 years. The spring NPP indicated the largest increase rate, while the summer NPP was with the largest increase in magnitude. The response of NPP to climate changes varied with different vegetation types. The increased NPP was primarily led by an advanced growing season for broadleaf evergreen forest, needle-leaf evergreen forest, and needle-leaf deciduous forest, whilst that was mainly due to enhanced vegetation activity (amplitude of growth cycle) during growing season for broadleaf deciduous forest, broadleaf and needle-leaf mixed forest, broadleaf trees with groundcover, perennial grasslands, broadleaf shrubs with grasslands, tundra, desert, and cultivation. The regions with the largest increase in spring NPP appeared mainly in eastern China, while the areas with the largest increase in summer NPP occurred in most parts of Northwestern China, Qinghai-Xizang Plateau, Mts. Xiaoxinganling-Changbaishan, Sanjiang Plain, Songliao Plain, Sichuan Basin, Leizhou Peninsula, part of the middle and lower Yangtze River, and southeastern mountainous areas of China. In autumn, the largest NPP increase appeared in Yunnan Plateau-Eastern Xizang and the areas around Hulun Lake. Such different ways of the NPP responses depended on regional climate attributes and their changes. 展开更多
关键词 Carnegie-Ames-Stanford-Approach (CASA) model net primary production (NPP) seasonal change normalized difference vegetation index (NDVI) climate change
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Interannual Variation in Terrestrial Ecosystem Carbon Fluxes in China from 1981 to 1998 被引量:35
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作者 曹明奎 陶波 +2 位作者 李克让 邵雪梅 Stephen D PRIENCE 《Acta Botanica Sinica》 CSCD 2003年第5期552-560,共9页
A dynamic biogeochemical model was used to estimate the responses of China's terrestrial net primary productivity (NPP), soil heterotrophic respiration (HR) and net ecosystem productivity (NEP) to changes in clima... A dynamic biogeochemical model was used to estimate the responses of China's terrestrial net primary productivity (NPP), soil heterotrophic respiration (HR) and net ecosystem productivity (NEP) to changes in climate and atmospheric CO2 from 1981 to 1998. Results show that China's total NPP varied between 2.89 and 3.37 Gt C/a and had an increasing trend by 0.32% per year, HR varied between 2.89 and 3.21 Gt C/a and grew by 0.40% per year, Annual NEP varied between -0.32 and 0.25 Gt C but had no statistically significant interannual trend. The positive mean NEP indicates that China's terrestrial ecosystems were taking up carbon with a total carbon sequestration of 1.22 Gt C during the analysis period. The terrestrial NEP in China related to climate and atmospheric CO2 increases accounted for about 10% of the world's total and was similar to the level of the United States in the same period. The mean annual NEP for the analysis period was near to zero for most of the regions in China, but significantly positive NEP occurred in Northeast China Plain, the southeastern Xizang (Tibet) and Huang-Huai-Hai Plain, and negative NEP occurred in the Da Hinggan Mountains, Xiao Hinggan Mountains, Loess Plateau and Yunnan-Guizhou Plateau. China's climate at the time was warm and dry relative to other periods, so the estimated NEP is probably lower than the average level. China's terrestrial NEP may increase if climate becomes wetter but is likely to continue to decrease if the present warming and drying trend sustains. 展开更多
关键词 China net primary productivity (NPP) soil heterotrophic respiration (HR) net ecosystem productivity (NEP) climate change
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Effect of complex melt-refining treatment on microstructure and mechanical properties of sand-cast Mg–10Gd–3Y–0.5Zr alloy 被引量:3
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作者 梅俊 刘文才 +6 位作者 吴国华 张杨 张逸韬 洪毅恺 张若曦 肖旅 丁文江 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第6期1811-1821,共11页
The effect of complex melt-refining treatment (melt flux incorporating with rotating gas bubble stirring) on microstructure and mechanical behavior of the sand-cast Mg-10Gd-3Y-0.5Zr alloy was investigated. In additi... The effect of complex melt-refining treatment (melt flux incorporating with rotating gas bubble stirring) on microstructure and mechanical behavior of the sand-cast Mg-10Gd-3Y-0.5Zr alloy was investigated. In addition, the melt purifying mechanism of the complex melt-refining treatment for the sand-cast alloy was discussed systematically. The results show that the new melt-refining method can significantly improve melt quality and mechanical behavior of the tested alloy, i.e., compared to the reference unpttdfied alloy, the volume fraction of inclusions decreased from 0.47% to 0.28%, the ultimate tensile strength and elongation for T6-treated alloy increased from 245 MPa and 0.7% to 312 MPa and 4.5%, respectively. Especially, combining 1% flux with rotating gas bubble stirring can get even better purifying effectiveness than conventional sole 2% flux purification; the use of melt flux decreased by 50% and significantly reduced environmental pollution. 展开更多
关键词 magnesium alloy sand-cast PURIFICATION complex melt-refining mechanical property
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Study on Absorptive Capacity to Formaldehyde and Physiological and Biochemical Changes of Scindapsus aureus Based on the Regulation of LaCl_3 被引量:2
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作者 闫生荣 花海蓉 +1 位作者 张跃群 周青 《Agricultural Science & Technology》 CAS 2015年第12期2596-2599,共4页
[Objective] This study was to analyze LaCl3 sprayed onto Scindapsus au- reus on Chlorophyll content and plasmamembrane permeability of leaves of Scindap- sus aureus, in order to determinate a suitable dosage of LaCl3.... [Objective] This study was to analyze LaCl3 sprayed onto Scindapsus au- reus on Chlorophyll content and plasmamembrane permeability of leaves of Scindap- sus aureus, in order to determinate a suitable dosage of LaCl3. [Method] With Scindapsus aureus as the test subject, 110 households of 20 communities in the New District of Nantong were selected to investigate formaldehyde concentration in indoor air; and effect of LaCl3 on absorptive capacity to formaldehyde of Scindapsus aureus was studied through fumigating in laboratory. Simultaneously, its physiological and biochemical mechanism of formaldehyde resistance was studied. [Result] The re- sults showed that formaldehyde pollution of indoor air was serious in the New District of Nantong, and the degree of pollution was related to the time after decoration. The suitable concentration of LaCl3 for Scindapsus aureus was 20 mg/L. The ability to ab- sorb formaldehyde of Scindapsus aureus, which was calculated by per unit leaf area, was enhanced after spraying the suitable concentration of LaCl3 by 19.75%. When Scindapsus aureus was stressed by formaldehyde, chlorophyll content decreased by 39.87%, membrane permeability and cumulative MDA amount increased by 8.17% and 56.92%, respectively, and POD activity increased by 11.32%. However, by com- paring the group pre-sprayed with LaCl3 and the group not sprayed with LaCl3 under formaldehyde stress, chlorophyll content of Scindapsus aureus reduced lessly, mem- brane permeability and MDA both increased lessly, while POD activity increased more. [Conclusion] This study provides a new thinking direction for broadening of rare earth application and control measures of indoor air pollution. 展开更多
关键词 LACL3 Scindapsus aureus Absorptive capacity to formaldehyde Physio- logical and biochemical mechanism
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Electrochemical hydrogen compression and purification versus competing technologies: Part Ⅰ. Pros and cons 被引量:3
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作者 Maha Rhandi Marine Trégaro +2 位作者 Florence Druart Jonathan Deseure Marian Chatenet 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第5期756-769,共14页
It is undisputed that hydrogen will play a great role in our future energetic mix, because it enables the storage of renewable electricity(power-to-H2) and the reversible conversion into electricity in fuel cell, not ... It is undisputed that hydrogen will play a great role in our future energetic mix, because it enables the storage of renewable electricity(power-to-H2) and the reversible conversion into electricity in fuel cell, not to speak of its wide use in the(petro)chemical industry. Whereas in these applications, pure hydrogen is required, today’s hydrogen production is still largely based on fossil fuels and can therefore not be considered pure. Therefore, purification of hydrogen is mandatory, at a large scale. In addition, hydrogen being the lightest gas, its volumetric energy content is well-below its competing fuels, unless it is compressed at high pressures(typically 70 MPa), making compression unavoidable as well. This contribution will detail the means available today for both purification and for compression of hydrogen. It will show that among the available technologies, the electrochemical hydrogen compressor(EHC), which also enables hydrogen purification, has numerous advantages compared to the classical technologies currently used at the industrial scale. EHC has their thermodynamic and operational advantages, but also their ease of use. However, the deployment of EHCs will be viable only if they reach sufficient performances, which implies some specifications that their base materials should stick to. The present contribution will detail these specifications. 展开更多
关键词 Electrochemical hydrogen compression Hydrogen energy Electrochemical hydrogen purification Thermdynamics EFFICIENCY
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Impacts of land use and climate change on regional net primary productivity 被引量:8
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作者 高志强 刘纪远 +4 位作者 曹明奎 LI Kerang TAO Bo 《Journal of Geographical Sciences》 SCIE CSCD 2004年第3期349-358,共10页
Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Glob... Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Global Production Efficiency Model (GLO-PEM) for detecting thewidespread spatial and temporal characteristics of the impacts of climate and land use change onthe regional NPP. Our results show that over the past 20 years, the mean annual temperature in thestudy region has remarkably increased by more than 0.064 ℃, but over the same period, there hasbeen a 1.49 mm decrease in annual precipitation and decrease in NPP by an annual rate of 6.9 TgC.The NPP changes in the study region were greatly affected by the average temperature andprecipitation by ten-day periods as well as the seasonal temperature and precipitation in the studyregion. The correlation between seasonal NPP and seasonal precipitation and temperature is highlyconsistent with land cover spatially, and the correlation coefficient changes with the changes ofvegetation types. The analysis reveals that the related areas in land use change only take up 5.45%of the whole studied region, so the climate changes dominate the impacts on the NPP in the wholestudy region (90% of the total). However, land use plays an absolute dominative role in areas withland cover changes, accounting for 97% of the total. From 1981 to 2000, the NPP in the whole studyregion remarkably reduced due to obvious precipitation decrease and temperature rise. Between twoperiods of land use (about 10 years), the changes in climate are predicted to promote a decrease inNPP by 78 ( + -0.6) TgC, and integrated impacts of climate changes and land use to promote adecrease in NPP by 87(+-0.8) TgC. 展开更多
关键词 climate change land use change NPP GLO-PEM North China Northeast China
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Calculation of Environmental Capacity of Petroleum Hydrocarbon in Jiaozhou Bay 被引量:1
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作者 李克强 王修林 +4 位作者 邓宁宁 石晓勇 祝陈坚 韩秀荣 胡海燕 《Marine Science Bulletin》 CAS 2004年第1期53-59,共7页
The method has been established to calculate the environmental capacity (ECO), surplus environment capacity (SECO) of water with respect to marine petroleum hydrocarbons associated with oil (PHAOs) and the self-purifi... The method has been established to calculate the environmental capacity (ECO), surplus environment capacity (SECO) of water with respect to marine petroleum hydrocarbons associated with oil (PHAOs) and the self-purification capacity (SPCO) of main self-purification process to PHAOs in the Jiaozhou Bay, China, according to the dynamic model for distribution of marine PHAOs among multiphase environments. The variation of concentration of PHAOs in the Jiaozhou Bay is well simulated by the dynamic model. Based on the model, the ECo, SECo of water with respect to PHAOs in the Jiaozhou Bay were calculated during the last 10 years under the first-class and second-class quality standard requirement, according to SPCO of main self-purification process to PHAOs. The results show that about 200 tons of PHAOs could be discharged into the Jiaozhou Bay for maintaining the first class seawater quality standard, and about 600 tons of PHAOs for the second class seawater quality standard later. 展开更多
关键词 petroleum-hydrocarbon Jiaozhou Bay environmental capacity self-purification capacity kinetic model
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Study on the Ability of Coriander Water Purification
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作者 Shijie Tang 《International Journal of Technology Management》 2014年第2期20-22,共3页
In order to study on the water purification ability of coriander, according to the material of Iris pseudacorus, Pontederia cordata, Thalia dealbata, coriander, Lythrum salicaria as the research object, the paper carr... In order to study on the water purification ability of coriander, according to the material of Iris pseudacorus, Pontederia cordata, Thalia dealbata, coriander, Lythrum salicaria as the research object, the paper carries on the analysis and comparison of water purification ability under greenhouse conditions in the 3~6 month period. The results showed: N, P content of coriander organizational changes before and after the test. Physiological responses of different plants, coriander is not sensitive to the physiological responses to stress of sewage, sewage adaptability is relatively strong. Judging from the effect of different plants to the water, then spent force has highest the removal rate for TN, coriander has the strongest absorption capacity for TP, water purification plant is excellent 展开更多
关键词 sewage submerging CORIANDER purifying effect
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Improving Simulation of the Terrestrial Carbon Cycle of China in Version 4.5 of the Community Land Model Using a Revised V_(cmax) Scheme 被引量:4
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作者 WANG Yuan-Yuan XIE Zheng-Hui +1 位作者 JIA Bing-Hao YU Yan 《Atmospheric and Oceanic Science Letters》 CSCD 2015年第2期88-94,共7页
The maximum rate of carboxylation (Vcax) is a key photosynthetic parameter for gross primary produc- tion (GPP) estimation in terrestrial biosphere models. A set of observation-based Vcax values, which take the ni... The maximum rate of carboxylation (Vcax) is a key photosynthetic parameter for gross primary produc- tion (GPP) estimation in terrestrial biosphere models. A set of observation-based Vcax values, which take the ni- trogen limitation on photosynthetic rates into consideration, are used in version 4.5 of the Community Land Model (CLM4.5). However, CLM4.5 with carbon-nitrogen (CN) biogeochemistry (CLM4.5-CN) still uses an inde- pendent decay coefficient for nitrogen after the photosyn- thesis calculation. This means that the nitrogen limitation on the carbon cycle is accounted for twice when CN bio- geochemistry is active. Therefore, to avoid this double nitrogen down-regulation in CLM4.5-CN, the original Vcmax scheme is revised with a new one that only accounts for the transition between Vcmax and its potential value (without nitrogen limitation). Compared to flux tower- based observations, the new Vcmax scheme reduces the root-mean-square error (RMSE) in GPP for China's Mainland by 13.7 g C m-2 yr-1, with a larger decrease over humid areas (39.2 g C m 2 yr-1). Moreover, net primary production and leaf area index are also improved, with reductions in RMSE by 0.8% and 11.5%, respectively. 展开更多
关键词 CLM4.5 Vcmax gross primary production net primary production leaf area index
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Impacts of Climate Change on Forest Ecosystems in Northeast China 被引量:12
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作者 WANG Xiao-Ying ZHAO Chun-Yu JIA Qing-Yu 《Advances in Climate Change Research》 SCIE 2013年第4期230-241,共12页
This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China. The results show that in the context of global and regional warming, the growing season of coniferous ... This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China. The results show that in the context of global and regional warming, the growing season of coniferous forests has been increasing at an average rate of 3.9 d per decade. Regional warming favors the growth of temperate broad-leaved forests and has a detrimental effect on the growth of boreal coniferous forests. Over the past hundred years, the forest edge of the cool temperate zone in the southern Daxing'anling region has retreated 140 km northward. From 1896 to 1986, the northern boundary of broad-leaved forests in Heilongjiang province has extended northwestward about 290 km. Future climatic changes (until 2060) may lead to the northern deciduous needle forests moving out of China's territory altogether. The occurrence cycles of pests and diseases have shortened; their distribution ranges have expanded. The life cycle of tent caterpillars (Malacosoma neustria testacea Motschulsky) has shortened from 14-15 years in the past to 8-10 years now. The pine caterpillar (Dendrolimus tabulaeformis Tsai et Liu), which has spread within western Liaoning province and the nearby areas, can now be found in the north and west. Lightning fires in the Daxing'anling region have significantly increased since 1987, and August has become the month when lightning fires occur most frequently. Overall, the net primary productivity (NPP) of forest in Northeast China has increased. The NPP in 1981 was around 0.27 Pg C, and increased to approximately 0.40 Pg C in 2002. With the current climate, the broad-leaved Korean pine forest ecosystem acts as a carbon sink, with a carbon sink capacity of 2.7 Mg C hm-2. Although the carbon sink capacity of the forest ecosystems in Northeast China has been weakened since 2003, the total carbon absorption will still increase. The forest ecosystems in Northeast China are likely to remain a significant carbon sink, and will play a positive role in the mitigation of climate change. 展开更多
关键词 Northeast China forest ecosystem climate change
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Flocculation Kinetics of Chitosan 被引量:2
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作者 陈亮 林志艳 陈东辉 《Journal of Donghua University(English Edition)》 EI CAS 2003年第1期1-3,共3页
Under the various conditions, the experiments of flocculation of bentonite solution with chitosari were carried out. And the flocculation kinetics was studied by the changes of floe size along with time. The results s... Under the various conditions, the experiments of flocculation of bentonite solution with chitosari were carried out. And the flocculation kinetics was studied by the changes of floe size along with time. The results show that hydraulic gradient G (s-1) plays a key role in growing up of floe size and both of molecular weight and initial turbidity of bentonite solution influence the floe size in steady state and the time needed for steady floe size. 展开更多
关键词 CHITOSAN FLOCCULATION KINETICS
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Effect of Biodiesel on Oxidation Stability, Detergency and Antiwear Ability of Diesel Oil 被引量:9
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作者 Wu Jiang Chen Boshui +1 位作者 Fang Jianhua Wang Jiu (Department of Petrochemistry, Logistical Engineering University, Chongqing 401311) 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2011年第4期58-63,共6页
Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicat... Different contents of biodiesel and petrodiesel were incorporated into diesel engine oils. The oxidative stability, detergency and antiwear performance of the formulated diesel oils were evaluated. The results indicated that, compared with petrodiesel, biodiesel was more liable to promote oxidation degradation of diesel oils, leading to worse oxidative stability, detergency and antiwear ability of the oils. 展开更多
关键词 BIODIESEL diesel oil oxidation stability DETERGENCY antiwear ability
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Antioxidant power of phytochemicals from Psidium guajava leaf 被引量:14
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作者 钱和 NIHORIMBEREVenant 《Journal of Zhejiang University Science》 CSCD 2004年第6期676-683,共8页
Dried ground leaves of Psidium guajava L. (guava) were extracted by water and aqueous ethyl alcohol 50% (1:10) ratio, and the total phenolic content in the extracts was determined spectrophotometrically according to ... Dried ground leaves of Psidium guajava L. (guava) were extracted by water and aqueous ethyl alcohol 50% (1:10) ratio, and the total phenolic content in the extracts was determined spectrophotometrically according to Folin- Ciocalteu’s phenol method and calculated as gallic acid equivalent (GAE). Remarkably high total phenolic content 575.3 ±15.5 and 511.6±6.2 mg of GAE/g of dried weight material (for ethanol guava leaf extracts and water guava leaf extracts, respectively) were obtained. The antioxidant activity of lyophilized extracts was determined at ambient temperature by means of a 2,2-diphenyl-1-picrylhydryzyl (DPPH˙) colorimetry with detection scheme at 515 nm. The activity was evalu- ated by the decrease in absorbance as the result of DPPH˙ color change from purple to yellow. The higher the sample concentration used, the stronger was the free radical-scavenging effect. The results obtained showed that ascorbic acid was a substantially more powerful antioxidant than the extracts from guava leaf. On the other hand, the commercial guava leaf extracts and ethanol guava leaf extracts showed almost the same antioxidant power whereas water guava leaf extracts showed lower antioxidant activity. The parameter EC50 and the time needed to reach the steady state to EC50 concentration ( TEC50 ) affected the antiradical capacity of the sample. The antioxidant efficiency (AE) has been shown to be a more ade- quate parameter for selecting antioxidants than the widely used EC50. This study revealed that guava leaf extracts comprise effective potential source of natural antioxidants. 展开更多
关键词 Antioxidant capacity Radical-scavenging activity DPPH˙ free-radical COLORIMETRY GUAVA POLYPHENOL
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Nitrogen and phosphorus budgets of the Changjiang River estuary 被引量:2
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作者 李祥安 俞志明 +2 位作者 宋秀贤 曹西华 袁涌铨 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2011年第4期762-774,共13页
Eutrophication has emerged as a key environmental problem in Chinese coastal waters, especially in the Changjiang (Yangtze) River estuary. In this area, large nutrient inputs result in frequent harmful algal blooms an... Eutrophication has emerged as a key environmental problem in Chinese coastal waters, especially in the Changjiang (Yangtze) River estuary. In this area, large nutrient inputs result in frequent harmful algal blooms and serious hypoxia in bottom waters. Four cruises were made in the estuary in 2006 to assess the concentration and distribution of dissolved inorganic nitrogen (DIN) and phosphorus (DIP). The concentration of DIN decreased gradually in a linear relationship with salinity from the river mouth to outer waters, while DIP was relatively more dispersed. A modified box budget method was used to estimate nutrient fluxes in the estuary and its adjacent waters. Water and nutrient budgets as well as primary production and denitrification rates were estimated from the box budget model. Estimated water residence time in the estuary was about 11 d. The turbid mixing zone released 33% of DIN and 49% of DIP, while in the adjacent outer sea 17.9 mmol DIN/m2·d and 0.36 mmol DIP/m2·d were fixed. Dissolved inorganic phosphorus was imported from the deep open sea waters, supporting primary production and population growth in this zone. Net ecosystem production (NEP) was calculated at 38.2 mmol/m2·d in the outer estuary and the estimated rate (N-fixation minus denitrification) was negative (1.92 mmol/m2·d), implying that a large amount of input nitrogen was taken up by algae and recycled through denitrification in bottom water and sediment. 展开更多
关键词 NITROGEN PHOSPHORUS NUTRIENTS TRANSPORT budget model Changjiang (Yangtze) River estuary
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Long Term Evaluation of Green Vegetation Cover Dynamic in the Atacora Mountain Chain(Togo) and its Relation to Carbon Sequestration in West Africa 被引量:2
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作者 Fousseni FOLEGA Yao Agbélessessi WOEGAN +7 位作者 Dourma MARRA Kperkouma WALA Komlan BATAWILA Jean Leonardo SEBURANGA ZHANG Chun-yu PENG Dao-li ZHAO Xiu-hai Koffi AKPAGANA 《Journal of Mountain Science》 SCIE CSCD 2015年第4期921-934,共14页
The research was done in the Atacora Mountain chain in Togo which tended to assess the change of vegetation cover during a 24-year period.It also aims to evaluate the dynamic of the net primary productivity(NPP) of th... The research was done in the Atacora Mountain chain in Togo which tended to assess the change of vegetation cover during a 24-year period.It also aims to evaluate the dynamic of the net primary productivity(NPP) of the living plants over the same period.The Landsat imagery covering three different periods(1987, 2000, and 2011) was pre-processed to correct atmospheric and radiometric parameters as well as gapfilling the 2011 SCL-off images.Then, the vegetation indices such as NDVI(normalized difference vegetation index), SR(simple ratiovegetation index), SAVI(soil-adjusted vegetation index), and CASA(carnegie- ames- stanford approach)model for NPP were applied on these images after masking the study area.The results showed a quiet decrease in the vegetation cover.The vegetation loss was more significant from 2000 to 2011 than from1987 to 2000, and anthropogenic activities can be deemed as the main cause of the vegetation loss.The biomass assessment by NPP computation also showed a decrease over the time.Similar to the change of the vegetation cover, the ecosystem net productivity was very low in 2011 compared to 2000 and 1987.It seems that the general health condition of thevegetation, including its potentiality in carbon sinking,was negatively affected in this area, which has already been under threatened.A perpetual monitoring of these ecosystems by means of efficient techniques could enhance the sustainable management tools of in the framework of reducing emissions from deforestation and forest degradation(REDD). 展开更多
关键词 Vegetation cover NPP Carbon sinking Biomass TOGO
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