Journals
  Publication Years
  Keywords
Search within results Open Search
Please wait a minute...
For Selected: Toggle Thumbnails
Estimation of Agricultural Non-point Source Pollution Loads Based on Improved Export Coefficient Model
HU Qing, GUO Huaicheng, WANG Yuqi, ZHANG Yang, LI Zheng, FU Zhenghui, LU Wentao
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (4): 739-748.   DOI: 10.13209/j.0479-8023.2021.049
Abstract661)   HTML    PDF(pc) (1455KB)(93)       Save
The Dianchi watershed Basin was selected as a typical watershed. Considering the differences of regional natural geography, hydrometeorology and human activities, using 1 km×1 km grid data, the detailed simulation calculation of the pollutants entering the water source of agricultural sources is carried out. The rainfall driving factors, terrain driving factors, surface runoff factor, underground storage/groundwater runoff factor and interception factor are obtained. The average comprehensive water inflow coefficients of TN and TP from agricultural sources in Dianchi Basin in 2016 are 0.447 and 0.342 respectively, and the actual water inflow loads of TN and TP from agricultural sources in 2016 are 577.39 t and 167.62 t respectively. The results show that the discharge of agricultural source pollutants and the load of influent water have significant spatial variation in Dianchi Lake Basin. 81.0% of nitrogen and 74.2% of phosphorus were concentrated in Caohai land area and the north coast of the open sea. The largest emission was in the upper reaches of Panlong River, with nitrogen and phosphorus accounting for 21.9% and 20.2% respectively. It is also found that livestock and poultry breeding account for more than 90% of the total TN and TP emissions of from agricultural sources, which should be the focus of agricultural source pollution control. 
Related Articles | Metrics | Comments0
Cognitive Appraisal and Meaning in Life in Recalling of Past Events: The Emotion as a Mediator
PANG Zhuoyue, ZHUANG Shujie, WANG Yuqian, GAN Yiqun
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (5): 977-986.   DOI: 10.13209/j.0479-8023.2019.069
Abstract891)   HTML    PDF(pc) (696KB)(270)       Save
The purpose of this paper is to investigate the relationship among cognitive appraisal, emotion and meaning in life when individuals recall past events. Before and after 171 college students’ writing on the same thing about the national college entrance examination, this study set a structural equation model to explore the mediation effect of emotion between cognitive appraisal and meaning in life. After the effect of gender, year, pretest of emotion and meaning in life were controlled, results indicated that positive appraisal and negative appraisal could predict meaning in life through positive emotion instead of negative emotion.
Related Articles | Metrics | Comments0
Ecological Tension Index Assessment in China Based on RBFN Model
WANG Yuqi, CHENG Shupeng, LU Wentao, FU Zhenghui, GUO Huaicheng
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (1): 182-188.   DOI: 10.13209/j.0479-8023.2018.091
Abstract868)   HTML    PDF(pc) (1601KB)(205)       Save

This paper select related indexes of ecological tension to establish the RBFN (radial basis function network) model, which is trained and tested according to the research results of ecological tension at different time in different regions. Then, the model is used to evaluate ecological tension of China’s 31 provinces, autonomous regions and municipalities in 2008 and 2013, and the evaluation results visualization expressed with GIS. The results show that the half area is the ecological pressure security status, and Beijing has the largest ecological pressure all the time; 22 provincial administrative regions’ ecological tension are aggravated from 2008 to 2013; regionally, the ecological pressure is the largest in North China, and the smallest in the northwest.

Related Articles | Metrics | Comments0
Numerical Simulation Analysis for Low Temperature Plasma Ignition of Propane/Air
MU Yuntao;ZHENG Dianfeng;WANG Yuqing;LI Lihan;ZHANG Huiqiang
   2015, 51 (5): 791-798.   DOI: 10.13209/j.0479-8023.2015.083
Abstract1252)      PDF(pc) (3148KB)(680)       Save
In order to study the initiate mechanism of pulse detonation engine ignited by low temperature plasma through numerical simulation method, the low temperature plasma ignition discharge area was simplified into heat kernel with high temperature and high pressure considering the propane/air chemical reaction kinetics mechanism. The laminar finite-rate model in the FLUENT was used to simulate the combustion process from deflagration to detonation transition (DDT) initiated by low temperature plasma, and the process was analyzed minutely. The experimental results show that it is feasible to simplify the low temperature plasma ignition to the fire kernel of a certain pressure and temperature in numerical simulation under a reasonable boundary condition that the pressure is atmospheric pressure and the wall temperature is normal temperature. The ignition delay and measurement error results in that the detonation wave development time of the numerical simulation is shorter than that of experimental result. The measurement value of the experiment is close to the result in numerical simulation under the condition of normal pressure heat kernel and normal temperature wall.
Reference | Related Articles | Metrics | Comments0
Study on the Subcellular Distribution of Sm and Yb in Rat Liver Using Enriched Stable Isotope Tracer
LI Fuliang,WANG Yuqi,ZHANG Zhiyong,SUN Jingxin,CHAI Zhifang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract589)            Save
The enriched stable isotope tracer technique combined with Neutron Activation Analysis (NAA) and differential centrifugation was utilized to investigate the subcellular distribution of rare earth elements Sm and Yb in rat liver. 152Sm and 168Yb were selected for experiment as representatives of the light and heavy REEs, respectively. In order to verify the analytical quality, some standard reference materials were used. The distribution in subcellular fractions was similar for Sm and Yb, the highest contents of Sm and Yb were found in mitochondria, while the lowest in nuclei.
Related Articles | Metrics | Comments0
Determination of Rare Earth Elements in Chloroplasts by Neutron Activation Analysis
ZHANG Zhiyong,WANG Yuqi,LI Fuliang,CHAI Zhifang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract671)            Save
The contents of 8 rare earth elements(REEs)in chloroplasts of Brassia napus were determined by instrumental neutron activation analysis. The results indicated that there were trace amounts of REEs in the chloroplasts, which corresponded to 1 atom of REEs per 2000 chlorophyll molecules. This content was lower than the microelements already known essential for the process of photosynthesis such as Fe, Mn and Cu.
Related Articles | Metrics | Comments0