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Protection Methods to Reduce Nitrogen and Phosphorus Losses from Sloping Citrus Land in the Three Gorges Area of China

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Pedosphere 2015年第3期25卷 478-488页

作者： XIA li-Zhong liU Guo-Hua WU Yong-Hong MA li li yun-dong Institute of Soil Science Chinese Academy of Sciences

The increased application of chemical fertilizers in citrus orchards and the non-point source nitrogen(N) and phosphorus(P)diffusion threaten the fresh water quality of the Three Gorges Reservoir area of China. A 10-year field trial on sloping citrus lands was conducted to evaluate five protection methods for reducing N and P losses: 1) intercropping with perennial white clover(CW); 2) straw mulching of the soil surface(CS); 3) intercropping with yellow daylily contour hedgerows(CH); 4) an impermeable membrane buried in the soil along the contour lines(CM); and 5) intercropping with a rotation of wheat and peanut(CWP). An area of conventional citrus management was also maintained as the control(CK). The results showed that CM and CH were the most effective methods for reducing surface runoff. The sediment yield were reduced at the highest rate by CW and CH and was also significantly reduced by CS. Reduced runoff volume and sediment yield were the crucial mechanism for the reductions in N and P losses. Compared with the control, CW, CS, CH, and CM reduced annual runoff by 9%, 13%, 25%, and 30%, sediment yield by 77%, 55%, 71%, and 28%,N loss by 10%, 23% 36%, and 37%, and P loss by 39%, 31%, 27%, and 25%, respectively. CW, CS, CH, and CM were effective in reducing N and P losses from the sloping citrus land. However, over the long-term, surface soil nutrient accumulation in CW, CS, and CH diminished the benefit of those methods in reducing N and P losses. In addition, CWP increased soil erosion and nutrient loss,which showed that citrus intercropping with other crops was an unsuitable method for citrus sloping land in the Three Gorges area.

关键词： contour hedgerows impermeable membrane intercropping runoff sediment straw mulching

Long-Term Effects of Inorganic and Organic Amendments on Organic Carbon in a Paddy Soil of the Taihu Lake Region,China

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Pedosphere 2011年第2期21卷 186-196页

作者： MA li YANG lin-Zhang XIA li-Zhong SHEN Ming-Xing YIN Shi-Xue li yun-dong Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 (China) Institute of Agricultural Sciences in Taihu Lake Region Jiangsu Academy of Agricultural Science Suzhou 215155 (China) College of Environmental Science and Engineering Yangzhou University Yangzhou 225009 (China)

A long-term experiment set up in 1980 compared the effects of applying manures and chemical fertilizers on a paddy soil in the Taihu Lake region, China. Of the fourteen randomly distributed treatments consisting of different combinations of organic manure, inorganic nitrogen （N）, phosphorus （P）, and potassium （K）, and rice straw, eight were selected for the present study in 2007. Application of organic manure plus straw significantly increased soil organic carbon （SOC） content of the topsoil （0-10 cm） compared to that of chemical fertilizers alone. The content of SOC was relatively stable in the 10-30 cm layer in the chemical fertilizer treatments and in the 20-40 cm layer in the manure treatments. The stable carbon isotope ratio （513C） ranged from -24% to -28% and increased gradually with depth. The content of SOC was significantly （P 〈 0.05） negatively correlated with 513C. In the 0-20 cm layer, the 513C value significantly decreased in the treatments of manure alone （M）, manure and chemical N and P fertilizers （MNP）, manure and chemical N, P, and K fertilizers （MNPK）, manure, rice straw, and chemical N fertilizer （MRN）, and chemical N fertilizer and rice straw （CNR）, as compared with the no-fertilizer control. In the 30-50 cm layer, however, the ratio significantly increased in all the treatments except Treatment CNR. Mineralization of organic C peaked in the first 2-4 d of incubation and gradually leveled off thereafter over the first 3 weeks, being faster in the manure treatments than the chemical fertilizer treatments. The average rate of mineralization varied from 55.36 to 75.46 mL CO2 kg-1 d-1 and that of stable mineralization from 10 to 20 mL CO2 kg-1 d-1. In eight weeks of incubation, cumulative mineralization was always higher in the manure treatments than the chemical fertilizer treatments, being the highest in Treatment MRN. Combined humus in the soil was mainly （over 50%） composed of tightly combined fraction. The loosely combined humus and its ratio o

关键词： chemical fertilizer humus mineralization organic manure stable carbon isotope ratio

Simulation-based optimization of inner layout of a theater considering the effect of pedestrians

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Chinese Physics B 2020年第3期29卷 285-291页

作者： Qing-Fei Gao Yi-Zhou Tao Yan-Fang Wei Cheng Wu li-yun dong Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China College of Science Shanghai Institute of TechnologyShanghai 201418China College of Physical Science and Technology Yulin Normal UniversityYulin 537000China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai 200072China

We propose an extended cellular automaton model based on the floor field. The floor field can be changed accordingly in the presence of pedestrians. Furthermore, the effects of pedestrians with different speeds are distinguished, i.e., still pedestrians result in more increment of the floor field than moving ones. The improved floor field reflects impact of pedestrians as movable obstacles on evacuation process. The presented model was calibrated by comparing with previous studies. It is shown that this model provides a better description of crowd evacuation both qualitatively and *** we investigated crowd evacuation from a middle-size theater. Four possible designs of aisles in the theater are studied and one of them is the actual design in reality. Numerical simulation shows that the actual design of the theater is *** we optimize the position of the side exit in order to reduce the evacuation time. It is shown that the utilization of the two exits at bottom is less than that of the side exits. When the position of the side exit is shifted upwards by about 1.6 m,it is found that the evacuation time reaches its minimum.

关键词： cellular automaton floor field crowd evacuation optimization of pedestrian facilities

OSCILLATION AMPliTUDE OF THE FREE END OF A FLEXIBLY MOUNTED RIGID CYliNDER IN TRIANGLE ARRANGEMENT

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Journal of Hydrodynamics 1998年第3期10卷 101-110页

作者： Xu, Youheng dong, liyun Huang, dongqun Fudan Univ Shanghai China

Oscillation amplitude of the free end of a group of the three cylinders was studied. The results of three cylinder arrangement were compared with those of two cylinders in tandem/side-by-side arrangement under the same condition. The experimental results show that the rear cylinder of the three cylinders is affected more seriously than that of two cylinders in contrast arrangement. The main direction of oscillation is changed. The transversal oscillation is stronger than the longitudinal oscillation in the three cylinder arrangement. The transversal oscillation is much weaker than the longitudinal oscillation in the two cylinders arrangement. The large transversal oscillations are attained for the rear cylinder in the third arrangement (two cylinders in tandem arrangement with a side cylinder) at S/D=2.5 and 3.0.

关键词： Cylinders (containers) Flow measurement Oscillations Stability Water wave effects

Thoughts and Practice on Some Problems about Research and Application of Two-line Hybrid Rice

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Rice science 2011年第2期18卷 79-85页

作者： CHEN li-yun LEI dong-yang TANG Wen-bang XIAO Ying-hui Rice Research Institution Hunan Agricultural University Changsha 410128 China

The main problems about research and application of two-line hybrid rice were reviewed, including the confusing nomenclature and male sterile lines classification, the unclear characteristics of photoperiod and temperature responses and the unsuitable site selection for male sterile line and hybrid dce seed production. In order to efficiently and accurately use dual-purpose genic male sterile lines, four types, including PTGMS （photo-thermo-sensitive genic male sterile rice）, TGMS （thermo-sensitive genic male sterile rice）, reverse PTGMS and reverse TGMS, were proposed. A new idea for explaining the mechanism of sterility in dual-purpose hybrid rice was proposed. The transition from sterile to fertile was involved in the cooperative regulation of major-effect sterile genes and photoperiod and/or temperature sensitive ones. The minor-effect genes with accumulative effect on sterility were important factors that affected the critical temperature of sterility transfer. In order to make better use of dual-purpose lines, the characterization of responses to photoperiod and temperature of PTGMS should be made and the identification method for the characterization of photoperiod and temperature responses of PTGMS should also be put forward. The optimal ecological site for seed production could be determined according to the historical climate data and the requirements for the meteorological conditions during the different periods of seed production.

关键词： two-line hybrid rice dual-purpose genic male sterile line photoperiod and temperature characteristics seed production seed propagation

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计算机通信网中的窗口体制分析

国防科技大学学报 2000年第2期22卷 78-81页

作者：李冬云中南工业大学计算机系湖南长沙410007

给出了计算机通信网中的窗体制描述 ,针对数据链路层和网络层运用的窗体制 ,分别进行了分析。讨论了不同层次上窗体制运用中的参数。

关键词：计算机通信网络窗口体制数据链路层

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初中英语教师专业发展研究:现状与对策

河北师范大学学报（教育科学版） 2012年第6期14卷 33-38页

作者：李冬耘廊坊师范学院外国语学院河北廊坊065000

针对我省参加2010年"国培计划"的156名初中英语教师,从生活状况、工作环境、教学情况、科研情况、专业现状、发展需求6个方面进行了专业发展现状调查。调查显示我省初中英语教师的职业幸福感偏低,专业满意度偏低;由于担心影响考试成绩,... 详细信息

针对我省参加2010年"国培计划"的156名初中英语教师,从生活状况、工作环境、教学情况、科研情况、专业现状、发展需求6个方面进行了专业发展现状调查。调查显示我省初中英语教师的职业幸福感偏低,专业满意度偏低;由于担心影响考试成绩,不少学校没有实施教改,"穿新鞋,走老路"的现象广泛存在;教师普遍缺乏专业发展的自觉性和动力;教师排斥理论学习、排斥教研/科研。基于调查结果,对我省初中英语教师专业发展提出一些建议和对策。

关键词：专业发展初中英语教师现状对策

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一般支撑条件下横向流中弹性圆柱的响应

工程力学 2015年第2期32卷 227-232,256页

作者：李云东杨翊仁李鹏西南交通大学力学与工程学院成都610031 四川理工学院理学院自贡643000

该文以横向流方形圆柱阵中的单根、两端带有一般支撑条件圆柱的流致振动现象进行研究。考虑圆柱的横向变形及其对轴力的影响,建立了系统动力学方程。分析了系统的稳定性及在不同流速条件下出现的复杂非线性行为,该文以分岔图、相平面图... 详细信息

该文以横向流方形圆柱阵中的单根、两端带有一般支撑条件圆柱的流致振动现象进行研究。考虑圆柱的横向变形及其对轴力的影响,建立了系统动力学方程。分析了系统的稳定性及在不同流速条件下出现的复杂非线性行为,该文以分岔图、相平面图、庞加莱映射图来刻画流速变化对圆柱振动的影响。研究结果表明,系统的初始预应力,降低了圆柱的稳定性;当流速较小时,系统首先表现为周期运动;随着流速增大,系统进入概周期运动,该系统未发生混沌运动。

关键词：圆柱阵流致振动概周期分岔庞加莱映射

维普期刊数据库博看期刊

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英语专业新生培训课程的实验报告

山西师大学报（社会科学版） 2005年第3期32卷 140-144页

作者：李冬耘廊坊师范学院外语系河北廊坊065000

大学新生面对新的学习环境、学习内容、教学方法、管理模式等,感到不适应、不知所措,影响了他们的学习积极性。学生非常需要教师的指导。培训课程首先通过问卷调查形式了解学生的语言学习观念和语言学习策略,根据其中反映出的问题,教师... 详细信息

大学新生面对新的学习环境、学习内容、教学方法、管理模式等,感到不适应、不知所措,影响了他们的学习积极性。学生非常需要教师的指导。培训课程首先通过问卷调查形式了解学生的语言学习观念和语言学习策略,根据其中反映出的问题,教师有针对性地在语言学习理论,语言学习策略,学习任务和学习要求等方面对学生进行指导、培训,目的是帮助学生尽快适应大学学习,学会如何学习外语,成为独立的学习者。

关键词：新生学习者培训语言学习策略语言学习观念