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线上线下混合实验教学模式研究 被引量:145
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作者 马超 曽红 王宏祥 《实验室研究与探索》 CAS 北大核心 2019年第5期185-189,共5页
MOOC是目前高校教学采用的一种重要方法,实验教学是培养学生实践动手能力和创新能力的主要途径。在将MOOC应用于实验教学可行性分析的基础上,提出了一种线上线下混合实验教学新模式。这种教学模式以"学生为主体、教师为主导"... MOOC是目前高校教学采用的一种重要方法,实验教学是培养学生实践动手能力和创新能力的主要途径。在将MOOC应用于实验教学可行性分析的基础上,提出了一种线上线下混合实验教学新模式。这种教学模式以"学生为主体、教师为主导"的教学理念为基础,融合了MOOC线上教学与实验线下课堂教学的优点,设计了课前预习、课堂实验、课后分析以及拓展训练4个环节,能够对学生展开综合培养。将该实验教学模式应用到学校机械设计课程实验教学中,结果表明,不仅能够提高学生对知识的理解和掌握,还能提高他们的自主学习能力、实践能力和创新能力。 展开更多
关键词 混合实验教学模式 线上线下 自主学习 实践能力 创新能力
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经济周期下的中国制造企业服务转型:嵌入还是混入 被引量:70
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作者 陈漫 张新国 《中国工业经济》 CSSCI 北大核心 2016年第8期93-109,共17页
服务转型是制造企业由产品生产商转为服务提供商的重新定位过程。实施嵌入式服务转型的企业提供与现有产品在价值链上拥有战略匹配关系的服务;而实施混入式服务转型的企业在产品之外,开发与产品不相关的新服务业务。本文基于305家上市... 服务转型是制造企业由产品生产商转为服务提供商的重新定位过程。实施嵌入式服务转型的企业提供与现有产品在价值链上拥有战略匹配关系的服务;而实施混入式服务转型的企业在产品之外,开发与产品不相关的新服务业务。本文基于305家上市制造企业2001—2013年的面板数据,检验了两种服务转型模式对企业绩效(托宾Q值)的影响。研究发现,嵌入式服务转型能够提升企业绩效,而混入式服务转型对企业绩效无显著作用。并且,在经济紧缩期,虽然大企业和小企业均可实施嵌入式服务转型以提升产品附加价值,但是小企业不可实施混入式服务转型,以避免在经济不景气时分散企业资源。在经济扩张期,大企业应当实施嵌入式服务转型以延伸价值链,小企业实施混入式服务转型以拓展业务范围,但是大企业不可实施混入式服务转型,以避免经营过程中的战略失衡。 展开更多
关键词 服务转型 嵌入 混入 经济扩张 经济紧缩
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表面活性剂的复配及其工业应用 被引量:53
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作者 杨锦宗 张淑芬 《日用化学工业》 CAS CSCD 北大核心 1999年第2期26-32,共7页
介绍了各种类型表面活性剂的复配及在18种行业中工业级的应用情况
关键词 表面活性剂 应用 复合配方 配方
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Unstable Head-Flow Characteristic Generation Mechanism of a Low Specific Speed Mixed Flow Pump 被引量:53
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作者 Masahiro MIYABE Hideaki MAEDA +1 位作者 Isamu UMEKI Yoshinori JITTANI 《Journal of Thermal Science》 SCIE EI CAS CSCD 2006年第2期115-120,144,共7页
This paper treats the flow instabilities in a mixed flow pump with a vaned diffuser. Test pump has a positive slope of a head-flow performance curve at 65% flow rate of BEP (Best Efficiency Point) because of a rotatin... This paper treats the flow instabilities in a mixed flow pump with a vaned diffuser. Test pump has a positive slope of a head-flow performance curve at 65% flow rate of BEP (Best Efficiency Point) because of a rotating stall. Dynamic Particle Image Velocimetry (PIV) and pressure fluctuation measurements are used for investigating the propagation mechanism of a rotating stall. It was found that unstable performance was caused by periodical large scale abrupt backflow generated from the vaned diffuser to the outlet of impeller. Further, the relation between the static pressure at the inlet of diffuser vane and the internal flow condition was clarified. From these experimental results, in order to improve the positive slope of a head-flow performance curve, to suppress the growth of strong vortex toward the inlet of diffuser vane was proved to be a key point. 展开更多
关键词 mixed flow pump vaned diffuser flow instabilities rotating stall dynamic PIV
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福建含笑杉木混交林生物量和土壤肥力的研究 被引量:39
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作者 郑郁善 黄宝龙 《南京林业大学学报(自然科学版)》 CAS CSCD 1998年第2期49-52,共4页
对福建含笑纯林和混交林进行造林试验,研究了5年生不同造林模式的林分生物量和培肥土壤能力。结果表明,福建含笑和杉木行间混交林具有较高的林分总生物量和乔木层生物量(85.48t/hm2、78.48t/hm2),而杉木纯林... 对福建含笑纯林和混交林进行造林试验,研究了5年生不同造林模式的林分生物量和培肥土壤能力。结果表明,福建含笑和杉木行间混交林具有较高的林分总生物量和乔木层生物量(85.48t/hm2、78.48t/hm2),而杉木纯林和乔木层总生物量均最低,仅为52.04t/hm2和43.04t/hm2。行间混交模式的土壤团聚体最好,结构破坏率小,土壤容重下降;土壤孔隙度和土壤通气度增大,分别比杉木纯林大14.5%和3.66%。行间混交林土壤有机质、氮、磷、钾含量明显高于杉木纯林,土壤酶活性明显加强,更有利于林木生长。 展开更多
关键词 福建 含笑 杉木 混交林 生物量 土壤肥力
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脂肪干细胞HLA分子表达与体外抑制淋巴细胞增殖的实验研究 被引量:34
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作者 崔磊 尹烁 +4 位作者 杨平 刘波 张英 刘伟 曹谊林 《中华医学杂志》 CAS CSCD 北大核心 2005年第27期1890-1894,共5页
目的研究脂肪干细胞(adiposederivedstemcells,ADSCs)表面免疫分子的表达以及体外调节淋巴细胞反应的功能,以期为组织工程提供同种异体种子细胞来源。方法从临床脂肪抽吸术丢弃脂肪组织中分离获取脂肪干细胞(共3例),体外培养至第2代,流... 目的研究脂肪干细胞(adiposederivedstemcells,ADSCs)表面免疫分子的表达以及体外调节淋巴细胞反应的功能,以期为组织工程提供同种异体种子细胞来源。方法从临床脂肪抽吸术丢弃脂肪组织中分离获取脂肪干细胞(共3例),体外培养至第2代,流式细胞仪检测免疫分子HLAI、HLAII的表达。1×105个/孔ADSC细胞刺激异体淋巴细胞,观察细胞增殖情况。以植物血凝素(PHA,2μg/ml)刺激淋巴细胞后,分别以(1×102、1×103、1×104、1×105)细胞/孔数量的异体脂肪干细胞加入反应体系中,观察淋巴细胞增殖情况;另一组在刺激同时加入白介素2(IL2,0.5ng/ml),检测脂肪干细胞抑制作用的逆转。分别以1×102~5细胞/孔数量的“第三者”脂肪干细胞或经IFNγ作用后脂肪干细胞加入混合双向淋巴细胞反应体系中,观察淋巴细胞增殖抑制情况。结果脂肪干细胞表达HLAI类分子,但未检测到HLAII类分子阳性表达。人IFNγ刺激48h后,HLAI表达未见明显增高,HLAII类分子表达明显增高。异体或经IFNγ作用的脂肪干细胞均未能刺激淋巴细胞体外增殖。脂肪干细胞可明显抑制PHA刺激的淋巴细胞增殖,IL2可逆转脂肪干细胞的抑制作用。脂肪干细胞可明显抑制双相混合淋巴细胞反应,抑制作用呈脂肪干细胞细胞数量依赖性;经IFNγ作用后抑制作用未见明显减弱。结论ADSC可在体外抑制淋巴细胞增殖反应,具有一定的调节淋巴细胞反应的能力,有可能成为组织工程或细胞治疗中同种异体细胞来源。 展开更多
关键词 脂肪干细胞 体外抑制 分子表达 实验研究 HLAII类分子 混合淋巴细胞反应 淋巴细胞增殖反应 细胞增殖情况 IFN-γ 流式细胞仪检测 细胞抑制作用 细胞增殖抑制 细胞体外增殖 免疫分子 细胞来源 同种异体 组织工程 反应体系
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Solid-state fermentation of corn-soybean meal mixed feed with Bacillus subtilis and Enterococcus faecium for degrading antinutritional factors and enhancing nutritional value 被引量:48
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作者 Changyou Shi Yu Zhang +1 位作者 Zeqing Lu Yizhen Wang 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2017年第4期925-933,共9页
Background: Corn and soybean meal(SBM) are two of the most common feed ingredients used in pig feeds.However, a variety of antinutritional factors(ANFs) present in corn and SBM can interfere with the bioavailability o... Background: Corn and soybean meal(SBM) are two of the most common feed ingredients used in pig feeds.However, a variety of antinutritional factors(ANFs) present in corn and SBM can interfere with the bioavailability of nutrients and have negative health effects on the pigs. In the present study, two-stage fermentation using Bacillus subtilis followed by Enterococcus faecium was carried out to degrade ANFs and improve the nutritional quality of corn and SBM mixed feed. Furthermore, the microbial composition and in vitro nutrient digestibility of inoculated mixed feed were determined and compared those of the uninoculated controls.Results: During the fermentation process, B. subtilis and lactic acid bacteria(LAB) were the main dominant bacteria in the solid-state fermented inoculated feed, and fermentation produced a large amount of lactic acid(170 mmo L/kg),which resulted in a lower pH(5.0 vs. 6.4) than the fermented uninoculated feed. The amounts of soybean antigenic proteins(β-conglycinin and glycinin) in mixed feed were significantly decreased after first-stage fermentation with B. subtilis. Inoculated mixed feed following two-stage fermentation contained greater concentratioin of crude protein(CP), ash and total phosphorus(P) compared to uninoculated feed, whereas the concentrations of neutral detergent fiber(NDF), hemicellulose and phytate P in fermendted inoculated feed declined(P < 0.05) by 38%, 53%, and 46%,respectively. Notably, the content of trichloroacetic acid soluble protein(TCA-SP), particularly that of small peptides and free amino acids(AA), increased 6.5 fold following two-stage fermentation. There was no difference in the total AA content between fermented inoculated and uninoculated feed. However, aromatic AAs(Phe and Tyr) and Lys in inoculated feed increased, and some polar AAs, including Arg, Asp, and Glu, decreased compared with the uninoculated feed. In vitro dry matter and CP digestibility of inoculated feed improved(P < 0.05) compared with the uninoculated feed.Conclusions: Our results s 展开更多
关键词 ANTINUTRITIONAL factors (ANFs) In VITRO DIGESTIBILITY mixed feed NUTRITIONAL value Two-stage fermentation
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P2P模式的系统结构研究 被引量:23
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作者 王丹 魏红 《沈阳航空工业学院学报》 2003年第2期35-37,共3页
本文首先介绍了什么是P2P和它的基本运作模式。
关键词 计算机 P2P模式 运作模式 资源共享 用户结点 网络互连
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纯林、混交林型园林绿地的生态效益 被引量:43
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作者 刘娇妹 李树华 +2 位作者 吴菲 刘剑 张志国 《生态学报》 CAS CSCD 北大核心 2007年第2期674-684,共11页
试验选择元大都城垣遗址公园西段4块不同结构类型的绿地为研究对象,即草坪、刺槐纯林、油松纯林、刺槐-油松混交林,每一块试验地的面积在1000m2左右,进行了连续8d的测试,通过试验观测与调查资料的分析,得出4块不同结构类型的园林绿地在... 试验选择元大都城垣遗址公园西段4块不同结构类型的绿地为研究对象,即草坪、刺槐纯林、油松纯林、刺槐-油松混交林,每一块试验地的面积在1000m2左右,进行了连续8d的测试,通过试验观测与调查资料的分析,得出4块不同结构类型的园林绿地在水平方向和垂直方向上温度、湿度、风速的分布规律及差异。结果表明,在水平方向上,在3种天气条件下,油松纯林的水平日平均温度最低、相对湿度最高;在晴朗天气一天中的高温时段,草坪的温度最高,相对湿度最低,刺槐-油松混交林的相对湿度最高,温度最低。在水平方向上,经SPSS方差分析,4种绿地间的温、湿度差异均达到显著水平(α=0.05)。在垂直方向上,4种绿地的温度随着高度的升高逐渐升高,而相对湿度则随着高度的升高而逐渐降低;相对于其他绿地,混交林的温度和相对湿度变化比较复杂。刺槐-油松混交林的降温增湿效果最好,草坪的降温增湿效果最差。混交林型绿地降低风速的效果好于2种纯林。根据4种绿地在夏季的降温增湿效应提出混交林是园林绿地中生态效益较好的植物配置模式并提出了营造城市园林绿地植物景观的建议。 展开更多
关键词 园林绿地 混交林 生态效益 温度 相对湿度 风速
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Mixed Logit模型及其在交通方式分担中的应用研究 被引量:36
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作者 王树盛 黄卫 陆振波 《公路交通科技》 CAS CSCD 北大核心 2006年第5期88-91,共4页
离散选择模型的典型代表Logit模型简洁易用的特点使其在经济、交通等领域得到了广泛的应用,但同时Logit模型的两个重要缺陷限制了其应用范围。在分析了Logit模型固有的两个缺陷和Mixed Logit模型的良好性质后,比较了Logit模型与Mixed Lo... 离散选择模型的典型代表Logit模型简洁易用的特点使其在经济、交通等领域得到了广泛的应用,但同时Logit模型的两个重要缺陷限制了其应用范围。在分析了Logit模型固有的两个缺陷和Mixed Logit模型的良好性质后,比较了Logit模型与Mixed Logit模型的差异,对Mixed Logit模型的算法进行了研究,并借助SAS统计软件提供的仿真算法给出了详细的工程实践应用范例。结果表明,Mixed Logit模型有着更丰富的物理含义,对个人出行交通方式选择行为的描述更符合实际。 展开更多
关键词 离散选择模型 mixed LOGIT模型 方式分担
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Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection for circumferential mixed hemorrhoids 被引量:44
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作者 Ming Lu Guang-Ying Shi +3 位作者 Guo-Qiang Wang Yan Wu Yang Liu Hao Wen 《World Journal of Gastroenterology》 SCIE CAS 2013年第30期5011-5015,共5页
AIM:To identify a more effective treatment protocol for circumferential mixed hemorrhoids.METHODS:A total of 192 patients with circumferential mixed hemorrhoids were randomized into the treatment group,where they unde... AIM:To identify a more effective treatment protocol for circumferential mixed hemorrhoids.METHODS:A total of 192 patients with circumferential mixed hemorrhoids were randomized into the treatment group,where they underwent Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection,or the control group,where traditional external dissection and internal ligation were performed.Postoperative recovery and complications were monitored.RESULTS:The time to wound healing was 12.96 ± 2.25 d in the treatment group shorter than 19.58 ± 2.71 d in the control group.Slight pain rate was 58.3% in the treatment group higher than 22.9% in the control group;moderate pain rate was 33.3% in the treatment group lower than 56.3% in the control group severe pain rate was 8.4% in the treatment group lower than 20.8% in the control group.No edema rate was 70.8% in the treatment group higher than 43.8% in the control group;mild local edema rate was 26% in the treatment group lower than 39.6% in the control group obvious local edema was 3.03% in the treatment group lower than 16.7% in the control group.No stenosis rate was 85.4% in the treatment group higher than 63.5% in the control group;moderate stenosis rate was 14.6% in the treatment group Lower than 27.1% in the control group severe anal stenosis rate was 0% in the treatment group lower than 9.4% in the control group.CONCLUSION:Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection is the optimal treatment for circumferential mixed hemorrhoids and can be widely applied in clinical settings. 展开更多
关键词 MILLIGAN-MORGAN HEMORRHOIDECTOMY mixed HEMORRHOIDS ANAL CUSHION Internal SPHINCTER
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WOMBAT—A tool for mixed model analyses in quantitative genetics by restricted maximum likelihood (REML) 被引量:44
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作者 MEYER Karin 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2007年第11期815-821,共7页
WOMBAT is a software package for quantitative genetic analyses of continuous traits, fitting a linear, mixed model; estimates of covariance components and the resulting genetic parameters are obtained by restricted ma... WOMBAT is a software package for quantitative genetic analyses of continuous traits, fitting a linear, mixed model; estimates of covariance components and the resulting genetic parameters are obtained by restricted maximum likelihood. A wide range of models, comprising numerous traits, multiple fixed and random effects, selected genetic covariance structures, random regression models and reduced rank estimation are accommodated. WOMBAT employs up-to-date numerical and computational methods. Together with the use of efficient compilers, this generates fast executable programs, suitable for large scale analyses. Use of WOMBAT is illustrated for a bivariate analysis. The package consists of the executable program, available for LINUX and WINDOWS environments, manual and a set of worked example, and can be downloaded free of charge from http://agbu. une.edu.au/-kmeyer/wombat.html 展开更多
关键词 SOFTWARE Variance components Genetic parameters mixed model Restricted maximum likelihood
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田林老山中山两类森林凋落物研究 被引量:28
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作者 梁宏温 《生态学杂志》 CAS CSCD 北大核心 1994年第1期21-26,共6页
田林老山中山两类森林凋落物研究梁宏温(广西农学院林学分院,南宁530001)StudiesontheLitterfallofTwoForestTypcsinMid—AltitudeofLaoshanMountaini... 田林老山中山两类森林凋落物研究梁宏温(广西农学院林学分院,南宁530001)StudiesontheLitterfallofTwoForestTypcsinMid—AltitudeofLaoshanMountaininTianlinCounty.¥L... 展开更多
关键词 evergreen and deciduous broadleaved mixed forest.Chinese fir plantation litterfall nutrient element return decompositon rate.
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Senome-wide Association Studies in Maize: Praise and Stargaze 被引量:39
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作者 Yingjie Xiao Haijun Liu +2 位作者 Liuji Wu Marilyn Warburton Jianbing Yan 《Molecular Plant》 SCIE CAS CSCD 2017年第3期359-374,共16页
Genome-wide association study (GWAS) has become a widely accepted strategy for decoding genotype- phenotype associations in many species thanks to advances in next-generation sequencing (NGS) technol- ogies. Maize... Genome-wide association study (GWAS) has become a widely accepted strategy for decoding genotype- phenotype associations in many species thanks to advances in next-generation sequencing (NGS) technol- ogies. Maize is an ideal crop for GWAS and significant progress has been made in the last decade. This review summarizes current GWAS efforts in maize functional genomics research and discusses future prospects in the omics era. The general goal of GWAS is to link genotypic variations to corresponding dif- ferences in phenotype using the most appropriate statistical model in a given population. The current re- view also presents perspectives for optimizing GWAS design and analysis. GWAS analysis of data from RNA, protein, and metabolite-based omics studies is discussed, along with new models and new popula- tion designs that will identify causes of phenotypic variation that have been hidden to date. The joint and continuous efforts of the whole community will enhance our understanding of maize quantitative traits and boost crop molecular breeding designs. 展开更多
关键词 GWAS OMICS mixed model population design functional genomics Zea mays
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Application and Prospect of Mixed Reality Technology in Medical Field 被引量:39
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作者 Hong-zhi HU Xiao-bo FENG +4 位作者 Zeng-wu SHAO Mao XIE Song XU Xing-huo WU Zhe-wei YE 《Current Medical Science》 SCIE CAS 2019年第1期1-6,共6页
Mixed reality(MR)technology is a new digital holographic image technology,which appears in the field of graphics after virtual reality(VR)and augmented reality(AR)technology,a new interdisciplinary frontier.As a new g... Mixed reality(MR)technology is a new digital holographic image technology,which appears in the field of graphics after virtual reality(VR)and augmented reality(AR)technology,a new interdisciplinary frontier.As a new generation of technology,MR has attracted great attention of clinicians in recent years.The emergence of MR will bring about revolutionary changes in medical education training,medical research,medical communication,and clinical treatment.At present,MR technology has become the popular frontline information technology for medical applications.With the popularization of digital technology in the medical field,the development prospects of MR are inestimable.The purpose of this review article is to introduce the application of MR technology in the medical field and prospect its trend in the future. 展开更多
关键词 mixed REALITY AUGMENTED REALITY VIRTUAL REALITY education SURGERY
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基于选择试验模型的生态系统服务支付意愿差异及全价值评估——以渭河流域为例 被引量:36
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作者 史恒通 赵敏娟 《资源科学》 CSSCI CSCD 北大核心 2015年第2期351-359,共9页
对流域生态系统服务进行全价值评估有利于相关流域治理政策的建立,实现流域的可持续发展。本文应用选择试验模型法,对我国流域生态系统服务的非市场价值进行评估,并以渭河流域陕西段为例进行实证研究。在生态功能属性和指标的合理选取... 对流域生态系统服务进行全价值评估有利于相关流域治理政策的建立,实现流域的可持续发展。本文应用选择试验模型法,对我国流域生态系统服务的非市场价值进行评估,并以渭河流域陕西段为例进行实证研究。在生态功能属性和指标的合理选取基础上进行选择试验模型设计和问卷调查,进一步分析渭河流域城乡居民对流域生态系统服务的认知差异,以及测算相关样本的支付意愿,最终进行非市场价值估算。研究结果表明:1相对于城镇居民,农村居民不在意水土流失方面生态系统服务的改善,而更关心水资源数量和质量,以及自然景观和生态旅游条件等方面的改善;2渭河流域居民对水资源质量这一生态指标具有最高的支付意愿,对水土流失强度这一生态指标具有次高的支付意愿,而对自然景观这一生态指标具有最低的支付意愿;3陕西省渭河流域平均每户居民每年愿意为渭河流域生态系统服务的改善支付624.22元,且城镇居民的支付意愿(830.34元/户)明显高于农村居民(525.46元/户)。陕西省渭河流域生态系统服务每年的非市场价值为8.68亿元。 展开更多
关键词 渭河流域 生态系统服务 全价值评估 选择试验模型 mixed LOGIT模型 支付意愿
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Cu–Mn–Ce ternary mixed-oxide catalysts for catalytic combustion of toluene 被引量:32
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作者 Hanfeng Lu Xianxian Kong +2 位作者 Haifeng Huang Ying Zhou Yinfei Chen 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第6期102-107,共6页
Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene ... Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1:2:4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the Ce O2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species. 展开更多
关键词 Cu-Mn-Ce mixed oxide Toluene Catalytic combustion Volatile organic compounds(VOCs)
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苜蓿和无芒雀麦混播草地种间竞争研究 被引量:33
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作者 陈积山 朱瑞芬 +2 位作者 高超 邸桂俐 张月学 《草地学报》 CAS CSCD 北大核心 2013年第6期1157-1161,共5页
为解决东北绥化地区冬春饲料不足,拓宽饲草料来源,以紫花苜蓿(Medicago satirva L.)和无芒雀麦(Bromus inermis L.)2种牧草5个豆禾混播比例建立混播草地,在4个生育期测定牧草高度、牧草产量、相对产量及相对产量总和,比较其混播牧草产... 为解决东北绥化地区冬春饲料不足,拓宽饲草料来源,以紫花苜蓿(Medicago satirva L.)和无芒雀麦(Bromus inermis L.)2种牧草5个豆禾混播比例建立混播草地,在4个生育期测定牧草高度、牧草产量、相对产量及相对产量总和,比较其混播牧草产量和组分等生产性能,探索高产优质混播草地建植与持续管理的调控机制。结果表明:5个混播组合和2个单播的产草量高低依次为AB_5>B>AB_4=AB_3>A>AB_1>AB_2,其中AB_5(无芒雀麦20%+苜蓿80%)混播组合产草量分别是单播苜蓿产量的1.28倍,是单播无芒雀麦的1.05倍,增产效果明显,体现了混播草地的生产力优势。通过混播草地种间竞争力变化的综合比较,AB_5组合在抽穗/开花期刈割时获得干产草量为12933.75 kg·hm^(-2),在本研究区建立高产优质多年生混播人工草地较为理想。 展开更多
关键词 混播 竞争力 无芒雀麦 苜蓿
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SEMI-GLOBAL C^1 SOLUTION TO THE MIXED INITIAL-BOUNDARY VALUE PROBLEM FOR QUASILINEAR HYPERBOLIC SYSTEMS 被引量:31
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作者 LI TA-TSIEN (LI DAQIAN), JIN YI Department of Mathematics, Fudan University, Shanghai 200433, China. 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2001年第3期325-336,共12页
By means of an equivalent invariant form of boundary conditions, the authors get the exis- tence and uniqueness of semi-global C1 solution to the mixed initial-boundary value problem for quasilinear hyperbolic systems... By means of an equivalent invariant form of boundary conditions, the authors get the exis- tence and uniqueness of semi-global C1 solution to the mixed initial-boundary value problem for quasilinear hyperbolic systems with general nonlinear boundary conditions. 展开更多
关键词 Semi-global C^1 solution mixed initial-boundary value problem Quasilinear hyperbolic system
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Eco-physiological Characteristics of Alfalfa Seedlings in Response to Various Mixed Salt-alkaline Stresses 被引量:30
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作者 Yong-Lin Peng Zhan-Wu Gao Ying Gao Guo-Fang Liu Lian-Xi Sheng De-Li Wang 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2008年第1期29-39,共11页
Soil salinization and alkalization frequently co-occur in nature, but little is known about the mixed effects of salt-alkaline stresses on plants. An experiment with mixed salts (NaCI, Na2SO4, NaHCO3 and Na2CO3) and... Soil salinization and alkalization frequently co-occur in nature, but little is known about the mixed effects of salt-alkaline stresses on plants. An experiment with mixed salts (NaCI, Na2SO4, NaHCO3 and Na2CO3) and 30 salt-alkaline combinations (salinity 24-120 mmollL and pH 7.03-10.32) treating Medicago sativa seedlings was conducted. The results demonstrated that salinity and alkalinity significantly affected total biomass and biomass components of seedlings. There were interactive effects of salt composition and concentration on biomass (P 〈 0.001). The interactions between salinity and alkalinity stresses led to changes in the root activity along the salinity gradient (P 〈 0.001). The effects of alkalinity on seedling survival rate were more significant than those of salinity, and the seedlings demonstrated some physiological responses (leaf electrolyte leakage rate and proline content) in order to adapt to mixed salt-alkaline stresses. It was concluded that the mixed salt-alkaline stresses, which differ from either salt or alkali stress, emphasize the significant interaction between salt concentration (salinity) and salt component (alkalinity). Further, the effects of the interaction between high alkalinity and salinity are more severe than those of either salt or alkali stress, and such a cooperative interaction results in more sensitive responses of ecological and physiological characteristics in plants. 展开更多
关键词 alfalfa (Medicago sativa) ALKALINITY mixed salt-alkaline stress salinity seedling.
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