期刊文献+
共找到4,412篇文章
< 1 2 221 >
每页显示 20 50 100
Measurement of the Level of Knowledge of the Sands Used in Constructions in Togo
1
作者 Ezoba Nayo Kossi Bollanigni Amey +1 位作者 Essé MawuléEdorh Komla Assogba Kassegne 《Journal of Minerals and Materials Characterization and Engineering》 2024年第4期225-235,共11页
Faced with the proliferation of quarries extracting silty sand and river sand used in the building and public works sector in Togo, recognition of the granular properties of these materials remains a major challenge f... Faced with the proliferation of quarries extracting silty sand and river sand used in the building and public works sector in Togo, recognition of the granular properties of these materials remains a major challenge for builders. This study aims to take stock of the use of sand in construction in Togo. One hundred and eighteen (118) sand quarries in operation, including thirty-eight (38) silty sand quarries and eighty (80) river sand quarries, were identified following surveys carried out among stakeholders involved in the chain of construction on 40% of the national territory. It appears from these surveys that river sands (59.43% to 84.68%) are prioritized over silty sands (15.32% to 40.57%). Three (3) main reasons are behind the choice of sand type;namely, proximity (28%), cleanliness (25%), good appearance (25%). These three (03) reasons partly explain the strong dependence of users on the sands located in their vicinity as well as the related expenses. Thus, making data available on the characteristics of sand, the materials most used in construction in Togo, would contribute to improving the housing conditions of the Togolese population. . 展开更多
关键词 SANDS TOGO Reasons for Use Construction
下载PDF
Mechanism,Kinetics,and Thermodynamic Characteristics for the Demetallization of Used Lubricating Oil via Pyrolysis
2
作者 Yang Haiyu Jiang Zhenxin +2 位作者 Chu Qingyan Jiang Peng Wang Ming 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS CSCD 2023年第2期113-127,共15页
This study analyzed the pyrolysis mechanism,developed a pyrolysis kinetic model,and determined the corresponding thermodynamic parameters for the removal of calcium from used lubricating oil using sulfurized calcium a... This study analyzed the pyrolysis mechanism,developed a pyrolysis kinetic model,and determined the corresponding thermodynamic parameters for the removal of calcium from used lubricating oil using sulfurized calcium alkyl phenolate(T-115B)as a model compound.The pyrolysis process and products were evaluated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.Visual inspection indicated that the removal of calcium from T-115B depended primarily on the destruction of micelles caused by the pyrolysis of compounds at high temperatures.The pyrolysis characteristics of T-115B at different heating rates were investigated by thermogravimetry and differential thermal analysis,which revealed two distinct pyrolysis phases.Thus,the pyrolysis mechanism can be described by a twostep model.The activation energy and thermodynamic parameters(ΔH,ΔG,andΔS)were determined by applying the Kissinger-Akahira-Sunose,Flynn-Wall-Ozawa,Friedman,and Starink methods;the average activation energies for T-115B pyrolysis obtained using these methods were 115.80,119.84,124.96,and 116.14 kJ/mol,respectively.Further,both stages of the pyrolysis reaction followed Fn mechanisms with n=1.39 in the first stage and n=0.86 in the second stage.This study provides reliable and effective pyrolysis models along with kinetic and thermodynamic parameters to facilitate the largescale industrial application of used lubricating oil. 展开更多
关键词 used lubricating oil sulfurized calcium alkyl phenolate pyrolysis decomposition kinetics THERMODYNAMICS non-isothermal method
下载PDF
Waste Recovery and Sustainable Development. A Case Study of Material Development from Used Tires in Africa
3
作者 Bachirou Bogno Paul-Salomon Ngohe Ekam +3 位作者 Mohammadou Sali Dieudonné Kidmo Kaoga Abderrezak Guenounou Michel Aillerie 《Smart Grid and Renewable Energy》 2023年第6期107-129,共23页
This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for t... This paper outlines a mechanical transformation process for rubber recycling, demonstrating the development of a new material from used tires. With the crumbs obtained using a crusher-compactor, a novel material for the manufacture of O-rings has been developed, with properties close to those found on the market. The process includes an experimental methodology of a sulfur vulcanization system choice and the quantification of ingredients, as well as the experimental determination of cure parameters. Mechanical tests on the samples completed the work by providing the mechanical characteristics of both unaged and aged (thermo-oxidative ageing) novel material. This process has a high potential for sustainable development and industrialization, making it a valuable contribution to the recycling of rubber in African developing countries. 展开更多
关键词 Sustainable Development Circular Economy used Tires Elastomers Recycling Vulcanization Parameters
下载PDF
Changes in Water Use Efficiency Caused by Climate Change,CO_(2) Fertilization,and Land Use Changes on the Tibetan Plateau 被引量:2
4
作者 Binghao JIA Xin LUO +1 位作者 Longhuan WANG Xin LAI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第1期144-154,共11页
Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere... Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere.However,under the combination of climate change and human intervention,the change in WUE is still unclear,especially on the Tibetan Plateau(TP).Therefore,satellite remote sensing data and process-based terrestrial biosphere models(TBMs)are used in this study to investigate the spatiotemporal variations of WUE over the TP from 2001 to 2010.Then,the effects of land use and land cover change(LULCC)and CO_(2) fertilization on WUE from 1981-2010 are assessed using TBMs.Results show that climate change is the leading contributor to the change in WUE on the TP,and temperature is the most important factor.LULCC makes a negative contribution to WUE(-20.63%),which is greater than the positive contribution of CO_(2) fertilization(11.65%).In addition,CO_(2) fertilization can effectively improve ecosystem resilience on the TP.On the northwest plateau,the effects of LULCC and CO_(2) fertilization on WUE are more pronounced during the driest years than the annual average.These findings can help researchers understand the response of WUE to climate change and human activity and the coupling of the carbon and water cycles over the TP. 展开更多
关键词 water use efficiency gross primary productivity EVAPOTRANSPIRATION Tibetan Plateau carbon and water cycle
下载PDF
Study on Rational Fertilization Scheme for Mulberry(Morus alba Linn) Used for Tea 被引量:1
5
作者 殷浩 王丽 +4 位作者 佟万红 黄盖群 危玲 郑继川 刘刚 《Agricultural Science & Technology》 CAS 2016年第11期2546-2550,2559,共6页
[Objective] This study was conducted to investigate effects of application amounts of N, P and K and their ratio on tea quality components in mulberry leaves. [Method] Effects of sole application and combined applicat... [Objective] This study was conducted to investigate effects of application amounts of N, P and K and their ratio on tea quality components in mulberry leaves. [Method] Effects of sole application and combined application of N, P and K on the yield and tea quality components of spring mulberry leaves were studied by 3-factor 3-level experiment, based on previous experiments. [Result] Combined ap- plication of 3 of N, P and K was better than sole application and combined appli- cation of 2 from them. Insufficient or excessive fertilization both significantly reduced yield of mulberry leaves and contents of tea quality components, such as 1-de- oxynojimycin (DNJ), flavonoids, tea polyphenols and amino acids. With the yield of spring mulberry leaves as a target, it is advised to apply N, P and K at rates of 240, 150 and 60 kg/hm^2 , respectively. [Conclusion] This study provides reference and theoretical basis for the establishment of raw material base of high-quality mul- berry tea. 展开更多
关键词 NPK Mulberry used for tea YIELD Tea quality
下载PDF
Effects of Used Battery on Key Enzyme Activity during the Germination of Wheat Seeds
6
作者 张恒 许兆棠 +2 位作者 李帅庆 韩玉良 陈智 《Agricultural Science & Technology》 CAS 2013年第1期135-137,143,共4页
[Objective] This study aimed to explore the effects of used battery lixivium on wheat germination. [Method] The wheat seeds were treated with used battery lix- ivium at different concentrations to detect the change of... [Objective] This study aimed to explore the effects of used battery lixivium on wheat germination. [Method] The wheat seeds were treated with used battery lix- ivium at different concentrations to detect the change of activities of amylase, pro- tease, pyruvate dehydrogenase (PDH) and polyphenol oxidase (PPO) during the ger- mination period. [Result] The results showed that the used battery affected enzyme activity. With the increase of concentration of used battery lixivium, trends of the changes of amylase and protease activities were not different. The activities were en- hanced at low concentrations of lixivium, while were inhibited at high concentrations. The tends of changes of pyruvate dehydrogenase (PDH) and polyphenol oxidase (PPO) activities were not consistent with that of either amylase or protease, which showed continuous downward trends with the increasing concentration of used battery lixivium. [Conclusion] This study is of great practical significance for understanding the effects of used battery lixivium on the germination of wheat seeds. 展开更多
关键词 used battery lixivium Germination of wheat seeds Activities of amylase protease pyruvate dehydrogenase(PDH) and polyphenol oxidase(PPO)
下载PDF
would与used to
7
作者 蒋建平 《中学英语园地(高三版)》 2002年第5期17-18,共2页
would与used to都可用来表示过去经常发生的动作,常常可以互相换用。例如:
关键词 WOULD used to” 高中 英语 词语辨析
下载PDF
would和used to表示“过去常常”用法小议
8
作者 鲁红霞 《中小学英语教学与研究》 2005年第6期62-62,共1页
would表示过去的习惯、习性、倾向等,相当于used to(过去常常)。例如:
关键词 WOULD used to” 用法 中学 英语
下载PDF
Used一词的用法辨析
9
作者 冉明志 《攀枝花学院学报》 2003年第3期56-56,共1页
关键词 used 英语词汇 用法 语法 不及物动词 过去分词
下载PDF
There used to…的反意疑问部分是什么?
10
作者 常建清 《英语知识》 2003年第12期42-42,共1页
[问][415]《全国成人高考统考全真模拟试卷英语》(新世界出版社p.56)有一道试题: There used to be a coffer shop next to your house,______? A.wasn’t there B.didn’t there C.wasn’t it D.didn't it 答案为A。请问这个答案对... [问][415]《全国成人高考统考全真模拟试卷英语》(新世界出版社p.56)有一道试题: There used to be a coffer shop next to your house,______? A.wasn’t there B.didn’t there C.wasn’t it D.didn't it 答案为A。请问这个答案对吗? [答]《牛津高阶英汉双解词典》指出。 展开更多
关键词 “There used to…” 成人高考 全国统一考试 英语 模拟试题 选择题 反意疑问句 用法 试题分析
下载PDF
used to与be used to用法辨析
11
作者 贺杰 《英语教师(高中)》 2003年第16期30-30,共1页
关键词 used to” “be used to” 用法辨析 高中 英语 语法 词法
下载PDF
BEHAVIOR OF FLOW STRESS OF ALUMINUM SHEETS USED FOR PRESSURE CAN DURING COMPRESSION AT ELEVATED TEMPERATURE 被引量:9
12
作者 G.S. Fu W.Z. Chen K. W. Qian 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2005年第6期756-762,共7页
The behavior of flow stress of Al sheets used for pressure can prepared by different melt-treatment during plastic deformation at elevated temperature was studied by isothermal compression test using Gleeble1500 dynam... The behavior of flow stress of Al sheets used for pressure can prepared by different melt-treatment during plastic deformation at elevated temperature was studied by isothermal compression test using Gleeble1500 dynamic hot-simulation testing machine. The results show that the AI sheets possess the remarkable characteristic of steady state flow stress when they are deformed in the temperature range of 350-500℃ at strain rates within the range of 0.01-10.0s^-1. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate, and an Arrhenius relationship with the temperature, which implies that the process of plastic deformation at elevated temperature for this material is thermally activated. Compared with the AI pieces prepared by no or conventional melt-treatment, hot deformation activation energy of AI sheets prepared by high-efficient melt-treatment is the smallest ( Q= 168.0kJ/mol), which reveals that the hot working formability of this material is very better, and has directly to do with the effective improvement of its metallurgical quality. 展开更多
关键词 Al sheets used for can melt-treatment plastic deformation at elevatedtemperature flow stress hot deformation activation energy
下载PDF
Refining Effect of a New Al3Ti1B1RE Master Alloy on Al Sheets Used for Can Manufacture and Behavior of Rare Earths in Master Alloy 被引量:11
13
作者 傅高升 陈文哲 钱匡武 《Journal of Rare Earths》 SCIE EI CAS CSCD 2003年第5期571-576,共6页
The refining effect of Al3Ti1B1RE master alloy on Al sheets used for pressure can manufacture and the behavior of mixed rare earths in master alloy were investigated with XRD, OM, SEM and EDAX. It is found that the r... The refining effect of Al3Ti1B1RE master alloy on Al sheets used for pressure can manufacture and the behavior of mixed rare earths in master alloy were investigated with XRD, OM, SEM and EDAX. It is found that the refining effect of the refiner on the material has superiority over foreign or domestic Al5Ti1B refiner, and the refiner still retains its refining ability for 6 h after adding it to molten Al, thus improving the strength and plasticity of the material remarkably. The excellent refining effect and stability of AlTiBRE refiner result from that RE can lower the surface energy of molten Al and improve the wetting characteristics of molten Al on refinement nuclei such as TiAl 3, TiB 2, etc., thus giving full play to the effect of heterogeneous nucleation and impeding the congregating tendency of TiB 2 phase in molten Al. At the same time, RE gathering in front of solid/liquid interface are also easy to cause composition supercooling in molten Al, thus impeding the growth of α Al grains and promoting α Al nucleation on refinement nuclei. In addition, RE also play certain role in purification and grain refinement, or modification, especially their effect of purification can improve the metallurgical quality of AlTiBRE master alloy. 展开更多
关键词 matel materials Al sheets used for can manufacture grain refinement Al3Ti1B1RE master alloy refining mechanism rare earths
下载PDF
In vitro screening of traditionally used medicinal plants in China against Enteroviruses 被引量:13
14
作者 Jin-Peng Guo Ji Pang Xin-Wei Wang Zhi-Qiang Shen Min Jin Jun-Wen Li 《World Journal of Gastroenterology》 SCIE CAS CSCD 2006年第25期4078-4081,共4页
AIM: To search for new antiviral agents from traditional Chinese medicine, specifically anti-enterovirosuses agents. METHODS: The aqueous extracts (AE) of more than 100 traditionally used medicinal plants in China... AIM: To search for new antiviral agents from traditional Chinese medicine, specifically anti-enterovirosuses agents. METHODS: The aqueous extracts (AE) of more than 100 traditionally used medicinal plants in China were evaluated for their in vitro anti-Coxsackie virus B3 activities with a MTT-based colorimetric assay. RESULTS: The test for AE of 16 plants exhibited anti- Coxsackie virus B3 activities at different magnitudes of potency. They can inhibit three steps (inactivation, adsorption and replication) during the infection. Among the 16 plants, Sargentodoxa cuneata (Oliv.) Rehd. et Wils., Sophora tonkinensis Gapnep., Paeonia veitchii Lynch, Spatholobus suberectus Dunn. and Cyrtorniurn fortunei J, sm. also have activity against other enterovirus, including Coxsackie virus 135, Polio virus I, Echo virus 9 and Echo virus 29. Cell cytotoxic assay demonstrated that all tested AE had CC50 values higher than their EC50 values. CONCLUSION: The sixteen traditionally used medicinal plants in China possessed antMral activity, and some of them merit further investigations. 展开更多
关键词 Traditional used medicinal plant China Antiviral activity Enterovirus Sargentodoxa cuneata(O/iv) Reid. et. W/Is. Sophora tonkinensis Gapnep. Paeonia veitchii Lynch. Cyrtomium fortunei J. sm. Spatholobus suberectus Dunn
下载PDF
Dry reusing and wet reclaiming of used sodium silicate sand 被引量:4
15
作者 Zitian FAN Naiyu HUANG +1 位作者 Huafang WANG Xuanpu DONG 《China Foundry》 SCIE CAS 2005年第1期38-43,共6页
Based on the characteristics of used sodium silicate sand and the different use requirements for recycled sand, "dry reusing and wet reclaiming of used sodium silicate sand" is considered as the most suitabl... Based on the characteristics of used sodium silicate sand and the different use requirements for recycled sand, "dry reusing and wet reclaiming of used sodium silicate sand" is considered as the most suitable technique for the used sand. When the recycled sand is used as support sand, the used sand is only reused by dry process including breaking, screening, dust-removal, etc., and it is not necessary that the used sand is reclaimed with strongly rubbing and scraping method, but when the recycled sand is used as facing sand (or single sand), the used sand must be reclaimed by wet method for higher removal rate of the residual binders. The characteristics and the properties of the dry reused sand are compared with the wet reclaimed sand after combining the different use requirements of support sand and facing sand (or single sand), and above the most adaptive scheme has also been validated. 展开更多
关键词 used SODIUM SILICATE SAND DRY reusing WET reclaiming
下载PDF
Feature of flow stress of aluminum sheet used for can during hot compression 被引量:4
16
作者 傅高升 钱匡武 +1 位作者 陈文哲 康积行 《中国有色金属学会会刊:英文版》 CSCD 2000年第5期671-674,共4页
The flow stress feature of aluminum sheet used for pressure can during plastic deformation at elevated temperature was studied by isothermal compression test using Gleeble 1 500 dynamic materials testing machine. The ... The flow stress feature of aluminum sheet used for pressure can during plastic deformation at elevated temperature was studied by isothermal compression test using Gleeble 1 500 dynamic materials testing machine. The experimental results show that the steady state deformation is remarkable when the material is deformed in the temperature range of 350~500 ℃ at strain rates within the range of 10 -2 ~10.0 s -1 . The material is sensitive to positive strain rate. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate, and an Arrhenius relationship with the temperature. Semi empirical constitutive equations of the flow stress are derived from all experimental data for tested material during plastic deformation at elevated temperature by polyelement linear regression analysis. [ 展开更多
关键词 aluminum SHEET used for CAN high temperature PLASTIC deformation compression flow stress
下载PDF
Wet reclamation of sodium silicate used sand and biological treatment of its wastewater by Nitzschia palea 被引量:5
17
作者 Wang Huafang Fan Zitian +2 位作者 Yu Shaoqiang Liu Fuchu Li Xuejie 《China Foundry》 SCIE CAS 2012年第1期34-38,共5页
The massive amount of sodium silicate in the used sand was a pollution source, especially in the waste water from the wet reclamation of used sand. A new process of wet reclamation by biologically treating the waste w... The massive amount of sodium silicate in the used sand was a pollution source, especially in the waste water from the wet reclamation of used sand. A new process of wet reclamation by biologically treating the waste water produced during the wet reclamation process of used sand was studied in the paper. In the work, the precultivation of N. palea was performed firstly, and three different scrubbing solutions: (1) tap water, (2) modified medium for N. palea, and (3) filtrate of the broth treated by N. palea for 15 days, were used. The results of the primary investigation show that a de-skinning ratio of 90% is obtained when using the scrubbing solution containing modified medium for N. palea at the ratio 1:2 of sand and scrubbing solution, and the maximal concentrations of Na^+ and SiO3^2- are 1.49 g.L-1 and 0.51 g.L-1, respectively. The results of the optimal biomass, pH value decrease and Na^+ and SiO32 consumption indicate the optimal incubation conditions are at the irradiance of 5,000 lux and 25 ℃. Using the filtrate of the broth treated by N. palea for 15 days as the scrubbing solution directly, a de-skinning ratio of 93% is the highest compared to the results of the tap water and the modified medium for N. palea. In the biological process using N. palea, less water is used and little wastewater is produced, which is advantageous to the purpose of green manufacturing and environmental protection. 展开更多
关键词 sodium silicate used sand biological reclamation method N.palea
下载PDF
CELLULOSE MEMBRANE USED AS STATIONARY PHASE OF MEMBRANE AFFINITY CHROMATOGRAPHY 被引量:2
18
作者 Wei GUO Zhen Hua SHANG Yi Nian YU and Liang Mo ZHOU (Dalian Institute of Chemical Physics, Chinese, Academy of Sciences P.O. Box 100, Datian 116012) 《Chinese Chemical Letters》 SCIE CAS CSCD 1994年第10期869-872,共4页
Cellulose membrane was used as Stahonary phase Of affinity chromeqraphy. A  ̄ for theprepeboon Of microPOre cellulose membone born cellulose balm is describ6d. Terne dyeS,Cibacron BIne F3GA and cave Red KZBP were immo... Cellulose membrane was used as Stahonary phase Of affinity chromeqraphy. A  ̄ for theprepeboon Of microPOre cellulose membone born cellulose balm is describ6d. Terne dyeS,Cibacron BIne F3GA and cave Red KZBP were immobilbe as amnty figeds. UP tO IO0 mgCibacron BIne F3G^ can be coupled ontO 1 g merebrane mainx. A membene cadridge cocainingblue affinty membranes was also Prepared. The flux of the cadridge was much superior to that Ofcolumn PaCked ed agarose as sepadsn odium. On this cable, the Chromatography ofhuman seam albumin was performed. 展开更多
关键词 AS STATIONARY used MEMBRANE OF AFFINITY CELLULOSE
下载PDF
A reversibly used cooling tower with adaptive neuro-fuzzy inference system 被引量:2
19
作者 吴加胜 张国强 +3 位作者 张泉 周晋 郭永辉 沈炜 《Journal of Central South University》 SCIE EI CAS 2012年第3期715-720,共6页
An adaptive neuro-fuzzy inference system(ANFIS) for predicting the performance of a reversibly used cooling tower(RUCT) under cross flow conditions as part of a heat pump system for a heating mode in winter was demons... An adaptive neuro-fuzzy inference system(ANFIS) for predicting the performance of a reversibly used cooling tower(RUCT) under cross flow conditions as part of a heat pump system for a heating mode in winter was demonstrated.Extensive field experimental work was carried out in order to gather enough data for training and prediction.The statistical methods,such as the correlation coefficient,absolute fraction of variance and root mean square error,were given to compare the predicted and actual values for model validation.The simulation results predicted with the ANFIS can be used to simulate the performance of a reversibly used cooling tower quite accurately.Therefore,the ANFIS approach can reliably be used for forecasting the performance of RUCT. 展开更多
关键词 reversibly used cooling tower HEATING adaptive neuro-fuzzy inference system fuzzy modeling approach
下载PDF
Risk Analysis of Sulfites Used as Food Additives in China 被引量:7
20
作者 ZHANG Jian Bo ZHANG Hong +4 位作者 WANG Hua Li ZHANG Ji Yue LUO Peng Jie ZHU Lei WANG Zhu Tian 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2014年第2期147-154,共8页
This study was to analyze the risk of sulfites in food consumed by the Chinese people and assess the health protection capability of maximum-permitted level (MPL) of sulfites in GB 2760-2011. Sulfites as food additi... This study was to analyze the risk of sulfites in food consumed by the Chinese people and assess the health protection capability of maximum-permitted level (MPL) of sulfites in GB 2760-2011. Sulfites as food additives are overused or abused in many food categories. When the MPL in GB 2760-2011 was used as sulfites content in food, the intake of sulfites in most surveyed populations was lower than the acceptable daily intake (ADI). Excess intake of sulfites was found in all the surveyed groups when a high percentile of sulfites in food was intaken. Moreover, children aged 1-6 years are at a high risk to intake excess sulfites. The primary cause for the excess intake of sulfites in Chinese people is the overuse and abuse of sulfites by the food industry. The current MPL of sulfites in GB 2760-2011 protects the health of most populations. 展开更多
关键词 Risk Analysis of Sulfites used as Food Additives in China
下载PDF
上一页 1 2 221 下一页 到第
使用帮助 返回顶部