期刊文献+
共找到75篇文章
< 1 2 4 >
每页显示 20 50 100
原位汽化固定床反应器设计与试验
1
作者 张安东 孟嘉鑫 +2 位作者 刘婷婷 高亮 李志合 《农业装备与车辆工程》 2024年第3期1-5,共5页
生物油具有含氧量高、酸性强、稳定性差、热值低、成分复杂等缺点,为了对生物油进行提质处理,基于原位汽化策略设计了一种固定床反应器,采用浸渍法制备Ni基催化剂,以气体产率、碳转化率、氢气选择性为主要评价指标,探究3种废弃秸秆热解... 生物油具有含氧量高、酸性强、稳定性差、热值低、成分复杂等缺点,为了对生物油进行提质处理,基于原位汽化策略设计了一种固定床反应器,采用浸渍法制备Ni基催化剂,以气体产率、碳转化率、氢气选择性为主要评价指标,探究3种废弃秸秆热解生物油的催化重整制氢效果。利用烟气分析仪检测的实时数据,计算出玉米、茄子、辣椒秸秆热解生物油的产氢率分别为38%、40%、33%;通过扫描电镜联合能谱(SEM)分析发现,表面碳沉积导致催化剂逐渐失活及催化重整制氢能力减弱。原位汽化固定床反应器设计合理、性能可靠,改进优化了生物油重整制氢生产工艺,提高了产氢效率,有利于生物质热解液化产物的高值利用。 展开更多
关键词 固定床 催化重整 生物油 氢气
下载PDF
草本竞争对蒙古栎更新幼苗高生长的影响机理
2
作者 朱丙轩 储泽毅 +2 位作者 南宏伟 孟嘉欣 刘卫敏 《生态学报》 CAS CSCD 北大核心 2024年第15期6828-6840,共13页
因生态位的高度重叠,森林更新早期草本植物同更新幼苗间存在着激烈的光能、养分及水分竞争,由此显著影响到森林更新过程。以山西省庞泉沟自然保护区蒙古栎更新幼苗为研究对象,设置4种草本竞争模式(无竞争、全竞争、地上竞争、地下竞争),... 因生态位的高度重叠,森林更新早期草本植物同更新幼苗间存在着激烈的光能、养分及水分竞争,由此显著影响到森林更新过程。以山西省庞泉沟自然保护区蒙古栎更新幼苗为研究对象,设置4种草本竞争模式(无竞争、全竞争、地上竞争、地下竞争),2种土壤养分梯度(4 g/m^(2)、32 g/m^(2)),2种土壤养分分布模式(均质、异质),进行草本竞争盆栽试验。结果表明:1)草本竞争、土壤养分状况对幼苗更新均存在显著影响(P<0.05)。其中,幼苗各生长指标在无竞争、地下竞争处理间的差异,显著表明地下竞争效应的存在性,地上竞争效应同理。2)基于线性模型,对幼苗苗高、叶片总面积、叶片总生物量、三个细根亚径级根系表面积而言,草本竞争主效应的贡献率分别为80.66%、67.49%、49.39%、40.26%、59.09%、53.26%,同土壤养分浓度相比,草本竞争的森林更新效应更高;在土壤养分异质条件下,二者交互效应甚至显著大于土壤浓度主效应;草本竞争各组分分析结果表明地下竞争效应的贡献率始终处于主导地位。3)基于结构方程模型,揭示草本竞争森林更新效应及其内在组分的具体作用途径。在无竞争与全竞争处理下,幼苗更新潜力对光能吸收及养分吸收的标准化回归系数分别为0.61、0.46,表明草本竞争主要通过光能吸收影响幼苗的更新过程;草本竞争内在组分的群组分析中,地上竞争与地下竞争相应的标准化系数分别为0.31、0.74,表明后者是主要的作用途径。在定量评价草本竞争及其内在组分森林更新效应的基础上,深入探讨其作用机理,加深了人们对其在森林更新早期生态效应的认识,为森林更新实践提供理论指导。 展开更多
关键词 森林更新 草本竞争 交互效应 结构方程模型 更新潜力
下载PDF
上市公司信息披露质量对股价极端波动的影响研究
3
作者 周金蒨 孟佳欣 蒋文江 《金融经济》 2024年第5期19-31,共13页
本文以2017—2021年深圳证券交易所A股上市公司为样本,运用联合泊松混合模型,从暴涨和暴跌两个角度探究信息披露质量对股价极端波动的影响情况。研究发现,二者之间存在显著的负相关性,并且当股票价格受信息披露质量的影响出现极端波动时... 本文以2017—2021年深圳证券交易所A股上市公司为样本,运用联合泊松混合模型,从暴涨和暴跌两个角度探究信息披露质量对股价极端波动的影响情况。研究发现,二者之间存在显著的负相关性,并且当股票价格受信息披露质量的影响出现极端波动时,相对于暴涨,出现暴跌的风险更高。此外,本文还基于联合泊松混合模型中的随机效应,探究了信息披露质量对股价极端波动影响在不同行业之间的差异。通过分析这种差异性,选择适合的股票来构建投资组合,能够帮助不同类型的投资者选择相应投资策略,实现更有效的风险管理。 展开更多
关键词 信息披露质量 股价极端波动 联合泊松混合模型 板块随机效应 投资策略
下载PDF
Raising the Chinese Voice
4
作者 meng jiaxin 《China Today》 2024年第10期74-75,共2页
As China celebrates the 40th anniversary of joining the International Atomic Energy Agency,an expert talks about how her organization is nurturing talents for overseas projects.
关键词 VOICE OVERSEAS ANNIVERSARY
下载PDF
The Old City of Langzhong
5
作者 meng jiaxin 《China Today》 2024年第3期74-78,共5页
This well-preserved historic city in Sichuan Province can trace its origins back to a bygone age,boasting a diverse culture and impressive legacies spanning multiple fields.THE old city of Langzhong is located in Nanc... This well-preserved historic city in Sichuan Province can trace its origins back to a bygone age,boasting a diverse culture and impressive legacies spanning multiple fields.THE old city of Langzhong is located in Nanchong City of southwest China’s Sichuan Province.It is considered to be among the best known ancient cities in China and its history can be traced back 2,300 years.Langzhong used to be the capital of the ancient Shu State during the Warring States Period(475-221 BC),later becoming the seat of local governments through different dynasties and the provincial capital for 20 years during the late Ming(1368-1644)and early Qing(1644-1911)dynasties. 展开更多
关键词 Province. BECOMING SOUTHWEST
下载PDF
The Ancient Town of Nanxun
6
作者 meng jiaxin 《China Today》 2024年第4期76-79,共4页
Built in 1252 during the Southern Song Dynasty(1127-1279),Nanxun boasts a rich cultural legacy that has accumulated throughout 700 years.THE ancient town of Nanxun is located in Nanxun District of Huzhou City,east Ch... Built in 1252 during the Southern Song Dynasty(1127-1279),Nanxun boasts a rich cultural legacy that has accumulated throughout 700 years.THE ancient town of Nanxun is located in Nanxun District of Huzhou City,east China’s Zhejiang Province,nestled in the prosperous heart of the Yangtze River Delta region. 展开更多
关键词 YANGTZE Nan ANCIENT
下载PDF
Huangyao Ancient Town
7
作者 meng jiaxin 《China Today》 2024年第6期74-78,共5页
HUANGYAO Ancient Town is located in the northeast of Zhaoping County in Hezhou City,south China’s Guangxi Zhuang Autonomous Region.Around 60 kilometers from downtown,the ancient town covers an area of over 3.2 square... HUANGYAO Ancient Town is located in the northeast of Zhaoping County in Hezhou City,south China’s Guangxi Zhuang Autonomous Region.Around 60 kilometers from downtown,the ancient town covers an area of over 3.2 square kilometers.It traces its origin to the early days of the Song Dynasty(960-1279).The town expanded during the Ming Dynasty(1368-1644)and flourished during the Qing Dynasty(1644-1911). 展开更多
关键词 TOWN ANCIENT DYNASTY
下载PDF
Ancient Zhenyuan, Gateway to East Guizhou
8
作者 meng jiaxin 《China Today》 2024年第1期76-80,共5页
This ancient city has a history going back over 2,000 years.It has witnessed the fusion of multiple ethnic cultures including the Miao,Dong,and Han,and hosts a number of cultural heritage sites.THE old town of Zhenyua... This ancient city has a history going back over 2,000 years.It has witnessed the fusion of multiple ethnic cultures including the Miao,Dong,and Han,and hosts a number of cultural heritage sites.THE old town of Zhenyuan is located in Zhenyuan County,Qiandongnan Miao and Dong Autonomous Prefecture in southwest China’s Guizhou Province.Covering an area of just around three square kilometers,it sits on the banks of the Wuyang River and is surrounded by mountains.Zhenyuan has been a county for more than 2,281 years and was the prefectural capital during the Yuan(1271-1368)and Qing(1644-1911)dynasties.It is a multicultural region,with Miao,Dong,and other ethnic minorities making up nearly half of the population. 展开更多
关键词 GUIZHOU GATEWAY SOUTHWEST
下载PDF
The Magic of Water Towns: Wuzhen and Xitang
9
作者 meng jiaxin 《China Today》 2024年第8期74-79,共6页
The appeal of Wuzhen and Xitang continues in the modern era,attracting millions of visitors every year to explore their beauty and cultural legacy.WUZHEN and Xitang,two old towns in Zhejiang Province in east China,are... The appeal of Wuzhen and Xitang continues in the modern era,attracting millions of visitors every year to explore their beauty and cultural legacy.WUZHEN and Xitang,two old towns in Zhejiang Province in east China,are historically known as places of singular serenity and sublime beauty.Today,they are top tourist destinations because of their well-preserved landscapes,gleaming water bodies,and bracing water town air. 展开更多
关键词 MAGIC attracting LANDSCAPE
下载PDF
Stitching Together New Lives with Ancient Yi Embroidery
10
作者 meng jiaxin 《China Today》 2024年第3期58-62,共5页
1,000-year-old Yi embroidery is taking a new lease of life in the modern era."During my childhood,Yi embroidery was the bright detailed rhododendron delavayi flowers which my mom sewed on clothes;later after I gr... 1,000-year-old Yi embroidery is taking a new lease of life in the modern era."During my childhood,Yi embroidery was the bright detailed rhododendron delavayi flowers which my mom sewed on clothes;later after I grew up,it has also become the means I use to provide a living for my family,"said Jin Ruirui,a Yi embroidery inheritor.Jin was born in 1989 in Anali Village,Mouding County,Chuxiong Yi Autonomous Prefecture of southwest China’s Yunnan Province.She is a deputy to the 14th National People’s Congress(NPC)and the president of the Yi Embroidery Innovation Association for the young people in Mouding County.She is also the eighth generation inheritor of Yi embroidery in her family. 展开更多
关键词 TOGETHER FLOWERS SOUTHWEST
下载PDF
Zhujiajiao Ancient Town:Stepping Back in Time
11
作者 meng jiaxin 《China Today》 2024年第12期76-80,共5页
As one of the best-preserved ancient water towns in Shanghai,Zhujiajiao retains its charm in contemporary China,attracting millions of visitors annually to take in its scenic waterways,cultural customs and historical ... As one of the best-preserved ancient water towns in Shanghai,Zhujiajiao retains its charm in contemporary China,attracting millions of visitors annually to take in its scenic waterways,cultural customs and historical architecture. 展开更多
关键词 annually attracting ANCIENT
下载PDF
Centuries-Old Villages in Southern Anhui:Xidi and Hongcun
12
作者 meng jiaxin 《China Today》 2024年第5期76-80,共5页
Xidi and Hongcun are two of the most representative ancient villages in the southern part of Anhui Province.Dating back to the Song Dynasty,they still preserve hundreds of residential buildings from the Ming and Qing ... Xidi and Hongcun are two of the most representative ancient villages in the southern part of Anhui Province.Dating back to the Song Dynasty,they still preserve hundreds of residential buildings from the Ming and Qing Dynasties. 展开更多
关键词 Province. ANHUI hundreds
下载PDF
The Old Town of Lijiang
13
作者 meng jiaxin 《China Today》 2024年第2期74-78,共5页
With a history of more than 800 years,Lijiang boasts picturesque sceneries,diverse cultures,and an abundance of well-preserved historical sites.THE old town of Lijiang,also known as the town of Dayan,is located in Guc... With a history of more than 800 years,Lijiang boasts picturesque sceneries,diverse cultures,and an abundance of well-preserved historical sites.THE old town of Lijiang,also known as the town of Dayan,is located in Gucheng District in Lijiang City,southwest China’s Yunnan Province.The current structures of the town can be traced back to the end of the Song Dynasty(960-1279)and the early era of the Yuan Dynasty(1271-1368). 展开更多
关键词 Province. SOUTHWEST SCENE
下载PDF
Education Through Games
14
作者 meng jiaxin 《China Today》 2024年第10期72-73,共2页
An Olympic scholar is teaching the Olympic culture in schools so that youngsters learn perseverance,resilience and fair play.
关键词 CULTURE TEACHING SCHOOLS
下载PDF
Water Town Zhouzhuang
15
作者 meng jiaxin 《China Today》 2024年第9期76-79,共4页
Every year this scenic water town is crowded with tourists and is an ideal place for those interested in getting a glimpse of the landscape that is characteristic of traditional southern Chinese towns.
关键词 LANDSCAPE INTERESTED TOURIST
下载PDF
Ancient City of Pingyao
16
作者 meng jiaxin 《China Today》 2024年第7期74-78,共5页
Within the towering walls surrounding the ancient city of Pingyao stand over 3,000 ancient buildings,designed in a typical traditional Chinese county style and presenting Chinese ritual traditions and recounting the t... Within the towering walls surrounding the ancient city of Pingyao stand over 3,000 ancient buildings,designed in a typical traditional Chinese county style and presenting Chinese ritual traditions and recounting the tales of Shanxi merchants who once walked these streets. 展开更多
关键词 walls ANCIENT ANCIENT
下载PDF
Miao Silver CraftingTechniques of Fenghuang County
17
作者 meng jiaxin ZHOU SHUYI 《China Today》 2024年第11期F0003-F0003,共1页
WOMEN of the Miao ethnic group in China love silver ornaments.In ancient times,the Miao people were always traveling rather than settling down.Legend has it that Miao people reforged their valuables by placing them in... WOMEN of the Miao ethnic group in China love silver ornaments.In ancient times,the Miao people were always traveling rather than settling down.Legend has it that Miao people reforged their valuables by placing them into furnaces and crafting them into wearable accessories,enabling them to carry their assets with them when they traveled.This tradition continues to this day.The craftsmanship of silver ornaments by the Miao was rated as one of the representative items of national intangible cultural heritage in 2006.Miao people living in Fenghuang County of Hunan Province excel in this craftsmanship. 展开更多
关键词 SILVER SILVER TRAVEL
下载PDF
有机氮和“三氮”在西部煤矿区地下水库迁移转化的实验研究 被引量:10
18
作者 张庆 罗绍河 +5 位作者 赵丽 王世东 田云飞 张垒 孟嘉馨 张智吉 《煤炭学报》 EI CAS CSCD 北大核心 2019年第3期899-905,共7页
基于浅埋深、薄基岩、厚煤层的赋存条件,在我国西部煤矿区往往排出富含有机氮和无机氮(硝酸盐氮、亚硝酸盐氮或氨氮)的矿井水,如果不经过处理就直接排放,会给生态环境带来严重危害。作为实现保水采煤、生态保护的措施之一,地下水库技术... 基于浅埋深、薄基岩、厚煤层的赋存条件,在我国西部煤矿区往往排出富含有机氮和无机氮(硝酸盐氮、亚硝酸盐氮或氨氮)的矿井水,如果不经过处理就直接排放,会给生态环境带来严重危害。作为实现保水采煤、生态保护的措施之一,地下水库技术已在我国多个西部生态脆弱煤矿区得到了实施,然而有关水质保障及安全运行的研究报道甚少。研究通过矸石柱模拟补连塔矿地下水库的水文地质环境,结合水中TN、"三氮"等理化指标的测试,开展了矿井水中有机氮和"三氮"的迁移转化规律研究。研究结果表明:渗流流量均值0.51 mL/min、1 016 h(12.54个孔隙体积数PV)内,在模拟的水-岩间的缺氧环境中,同时存在有机氮的矿化作用、亚硝酸盐及硝酸盐的反硝化作用。在实验初期的1.19~2.47 PV,有机氮浓度快速下降,而氨氮浓度快速上升,这说明试验初期有机氮的氨化作用较强。之后有机氮的矿化作用逐渐减弱,导致水中氨氮含量逐渐减小并趋于稳定。在矿井水C/N为2.32~3.08的条件下,较强的还原作用导致亚硝酸盐的去除率在99.9%以上、硝酸盐的去除效率在74%~90%。矿井水TN的去除效率在57%~71%,由于淋滤用液硝酸盐含量较低,因此TN的去除主要与亚硝酸盐的减少有关。有机物降解过程低分子量有机酸的生成使得水中H^+含量升高、淋出液pH值始终低于淋滤用液。研究结果可为地下水库技术的有效实施提供水质保障和安全运行方面的借鉴。 展开更多
关键词 保水采煤 西部煤矿区 地下水库 矿井水 有机氮 无机氮 煤矸石
下载PDF
复杂遮荫下基于改进GWO的光伏多峰MPPT控制 被引量:11
19
作者 付文龙 孟嘉鑫 +1 位作者 张赟宁 徐潘 《太阳能学报》 EI CAS CSCD 北大核心 2023年第3期435-442,共8页
光伏阵列在复杂遮荫环境下的P-U曲线呈现多个峰值导致最大功率跟踪(MPPT)算法失效,为此提出双层控制模型,在上层模型中将Levy飞行和多项式变异策略嵌入灰狼算法,构建Levy-变异灰狼优化算法(LPGWO)搜索全局最大功率点;在下层模型中采用... 光伏阵列在复杂遮荫环境下的P-U曲线呈现多个峰值导致最大功率跟踪(MPPT)算法失效,为此提出双层控制模型,在上层模型中将Levy飞行和多项式变异策略嵌入灰狼算法,构建Levy-变异灰狼优化算法(LPGWO)搜索全局最大功率点;在下层模型中采用扰动观察法对最大功率点进行局部跟踪,进而有效降低复杂遮荫环境下的功率振荡。仿真结果表明,在多峰MPPT控制中,所提模型具有跟踪速度快、收敛精度高、整体功率振荡小等特点,能有效提升复杂遮荫环境下光伏阵列的最大功率跟踪效率和精度。 展开更多
关键词 光伏阵列 最大功率点跟踪 灰狼优化算法 扰动观察法 复杂遮荫
下载PDF
环境因子对白桦、五角枫幼苗生长的影响 被引量:1
20
作者 孟嘉欣 南宏伟 +1 位作者 郭晋平 刘卫敏 《广西林业科学》 2023年第4期468-475,共8页
为探讨环境因子对不同树种幼苗影响的作用机理,以白桦(Betula platyphylla)和五角枫(Acer mono)为试验对象,设置4种竞争方式(无竞争、全竞争、地上竞争和地下竞争)、4种土壤养分浓度(0、8、16和32 g/m2)及2种养分分布水平(均、异质),分... 为探讨环境因子对不同树种幼苗影响的作用机理,以白桦(Betula platyphylla)和五角枫(Acer mono)为试验对象,设置4种竞争方式(无竞争、全竞争、地上竞争和地下竞争)、4种土壤养分浓度(0、8、16和32 g/m2)及2种养分分布水平(均、异质),分析不同环境因子对幼苗生长的影响。结果表明,生态环境对幼苗生长的影响在自然界中普遍存在,各环境因子之间既存在独立性又存在相关性。草本竞争对幼苗生长的影响大于土壤养分状况,生存空间是影响幼苗生长的关键因素。草本竞争对于幼苗的生长存在不利影响;环境因子影响幼苗生长主要反映在幼苗的生物量分配状况上;环境因子对幼苗生长的影响在两种树种间存在显著差异。 展开更多
关键词 草本竞争 土壤养分 冗余分析 结构方程模型 白桦 五角枫
下载PDF
上一页 1 2 4 下一页 到第
使用帮助 返回顶部