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Accessibility Comparison and Spatial Differentiation of Xi’an Scenic Spots with Different Modes Based on Baidu Real-time Travel

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Chinese Geographical Science 2019年第5期29卷 848-860页

作者： WANG Li CAO Xiaoshu LI Tao GAO Xingchuan School of Geography and Tourism Shaanxi Normal UniversityXi’an710119China Tourism College and Institute of Human Geography Xi’an International Studies UniversityXi’an710128China Northwest Land and Resource Research Centre ShaanxiNormal UniversityXi’an710119China

A study of the accessibility of a city’s scenic spots via different travel modes can contribute to optimization of tourism-related transportation while improving tourists’ travel-related satisfaction levels and advancing tourism. We systematically analyzed the accessibility of 56 scenic spots in Xi’an City, China, via car and public transport travel modes using the real-time travel function of the Baidu Maps API(Application Programming Interface) along with spatial analysis methods and the modal accessibility gap index of scenic spots. We obtained the following results. First, maximum and minimum travel times using public transport exceeded those using cars. Moreover, the accessibility of scenic spots via cars and public transport presented a circular spatial pattern of increasing travel time from the center to the periphery. Contrasting with travel by public transport, car travel showed a clear time-space compression effect. Second, accessibility of the scenic spots via cars and public transport showed some spatial heterogeneity, with no clear advantages of car accessibility in the central urban area. However, advantages of car accessibility were increasingly evident moving from the center to the periphery. Third, whereas the correlation of the modal accessibility gap index of scenic spots in Xi’an with global space was significantly positive, local spatial interdependence was only evident in some inner city areas and in marginal areas. Moreover, spatial heterogeneity was evident in two regions but was insignificant in other areas, indicating that the spatial interdependence of the modal accessibility gap index in most scenic spots was not apparent in terms of the overall effect of public transport routes, road networks, and the distribution of scenic spots. The improvement of public transport coverage in marginal areas and the optimization of public transport routes in central urban areas are essential tasks for improving travel using public transport in the future.

关键词： Baidu real-time travel car accessibility public transport accessibility modal accessibility gap scenic spots Xi’an City

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Developing sustainable summer maize production for smallholder farmers in the North China Plain: An agronomic diagnosis method

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Journal of Integrative Agriculture 2019年第8期18卷 1667-1679页

作者： CHEN Guang-feng CAO Hong-zhu CHEN Dong-dong ZHANG Ling-bo ZHAO Wei-li ZHANG Yu MA Wen-qi JIANG Rong-feng ZHANG Hong-yan ZHANG Fu-suo College of Resources and Environmental Sciences China Agricultural University Beijing 100193 P.R.China College of Resources and Environment Science Hebei Agricultural University Baoding 071001 P.R.China Key Laboratory of Plant-Soil Interactions Ministry of Education Beijing 100193 P.R.China National Agricultural Technology Extension and Service Center Ministry of Agriculture and Rural Affairs Beijing 100125 P.R.C hina

With an increasing population and changing diet structure, summer maize is increasingly becoming an important energy crop in China. However, traditional farmer practices for maize production are inefficient and unsustainable. To ensure food security and sustainable development of summer maize production in China, an improved, more sustainable farmer management system is needed. Establishing this system requires a comprehensive understanding of the limitations of current farming practice and the ways it could be improved. In our study, 235 plots from three villages in the North China Plain(NCP) were monitored. Maize production on farms was evaluated;our results showed that the maize yield and nitrogen partial factor productivity(PFPN) were variable on smallholder farms at 6.6–13.7 t ha^–1 and 15.4–88.7 kg kg^–1, respectively.Traditional farming practices also have a large environmental impact(nitrogen surplus:–64.2–323.78 kg ha^–1). Key yield components were identified by agronomic diagnosis. Grain yield depend heavily on grain numbers per hectare rather than on the 1 000-grain weight. A set of improved management practices(IP) for maize production was designed by employing a boundary line(BL) approach and tested on farms. Results showed that the IP could increase yield by 18.4% and PFPN by 31.1%, compared with traditional farmer practices(FP), and reduce the nitrogen(N) surplus by 57.9 kg ha^–1. However,in terms of IP effect, there was a large heterogeneity among different smallholder farmers’ fields, meaning that, precise technologies were needed in different sites especially for N fertilizer management. Our results are valuable for policymakers and smallholder farmers for meeting the objectives of green development in agricultural production.

关键词： smallholder farmers sustainable production yield gap agronomic diagnosis North China Plain

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中药材规范化生产(gap)10年:成果、问题与建议

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中国中药杂志 2014年第7期39卷 1143-1151页

作者：郭兰萍张燕朱寿东王桂华王秀张小波陈美兰何雅莉韩邦兴陈乃富黄璐琦中国中医科学院中药资源中心北京100700 道地药材国家重点实验室北京100700 中国中药协会北京100075 皖西学院生物与制药工程学院安徽六安237012

该文旨在总结中药材gap实施过程中取得的成果,在分析其存在问题的基础上,就中药材gap的进一步推行提出建议。作者认为中药材gap推行10年取得了很大成果,包括①颁布了中药材gap认证的一系列管理办法;②中药材规模化面积不断扩大;③农民... 详细信息

该文旨在总结中药材gap实施过程中取得的成果,在分析其存在问题的基础上,就中药材gap的进一步推行提出建议。作者认为中药材gap推行10年取得了很大成果,包括①颁布了中药材gap认证的一系列管理办法;②中药材规模化面积不断扩大;③农民及企业规范化种植中药材的意识增强;④形成了一批中药材gap基地;⑤中药材栽培理论和方法不断完善;⑥培养了一大批中药材gap生产及认证的专家和学者。gap生产中存在的问题主要包括:①对gap及其认证的认识和理解亟需深化;②gap认证基地布局不够合理;③地缘经济及小农经济耕作是中药材规范化和规模化生产的瓶颈;④比较效益偏低限制了gap的发展;⑤优良品种选育基础空白;⑥栽培技术不成熟导致生产过程风险较大;⑦土壤微生态恶化及连作障碍制约了中药材gap基地的可持续发展。为进一步促进中药材gap健康有序发展,作者提出以下建议:①改变生产模式,全面推动中药材gap生产;②建立健全中药材标准体系,推行中药材优质优价;③充分考虑地缘经济文化,大力推行中药材定向培育;④强化基础研究和成果转化推广,为中药材生产提供技术保障;⑤深化对gap的理解,大力推行生态种植和精细农业克服连作障碍。作者认为,虽然仍面临大量管理和技术问题,但中药材gap早已深入人心,并展现出巨大的前景。未来时日,随着人们对gap认识理解的不断加深,以及科技的巨大进步,gap生产将会不断与精准农业、生态农业等现代农业理论、方法及技术融合,并展现出更大的潜力和更广阔的前景。

关键词：中药材 gap 规范化生态种植精准农业

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Tech no logy gap,Reverse Technology Spillover and Domestic Innovation Performanee in Outward Foreign Direct Investment:Evidenee from China

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China & World Economy 2019年第2期27卷 1-23页

作者： Jin Hong Chongvang Zhou Yanrui Wu Ruicheng Wang Dora Marinova University of Science and Technology of China China University of Western Australia Australia. Nanjing University of Science and Technology China Curtin University Australia

This research adds to the literature studying the effects of outward foreign direct investment(OF DI)on domestic innovation performance and the moderating effect of a technology gap between host and home countries.New definitions of observed technology gap and expected technology'gap are proposed.An observed technology gap captures the existing differences in technology level between establishments,regions or countries.An expected technology'gap is an indication of the effort of imitating and learning from technology leaders.The corresponding measures and effects of observed and expected technology gaps on OFDI-induced reverse technology spillover are analyzed.OFDI in developed countries promotes innovation performance.However,OFDI in emerging markets hampers innovation performance.It is also found that regions with a wider observed technology^gap and a narrower expected technology gap can benefit more from OFDI.

关键词： innovation performance outward foreign direct investment reverse technology spillover technology gap

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Experimental study of the gap between track slab and cement asphalt mortar layer in CRTS I slab track

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Journal of Modern Transportation 2018年第3期26卷 173-178页

作者： Tao Wang Hengqiong Jia Zike Liu Zhao Wei Xiao Xie Shaoliang Wu Haiyan Li Metals and Chemistry Research Institute Academy of Railway Sciences China

gap exists in the interface of cement asphalt emulsion mortar and CRTS I track slab universally, which is more severe at four corners than other parts of the track slab. In this work, the temperature and elevation of CRTS I slab track with and without rail were measured continuously to study the influence mechanism of rail on the gap. The results show that the alternating temperature gradient of track slab is the main reason that causes the gap, and laying rail can efficiently decrease the gap size in the slab track without rail. Compared with the slab track without rail, the maximum elevation occurred at the corner, the maximum gapwidth and the maximum gap depth of the slab track with rail laid were decreased by 0.45 mm （25.7%）, 0.75 mm （46.6%） and 9.5 mm （59.4%）, respectively; meanwhile, the disqualification ratio at corners was reduced to 5.9%, which is 50% less than that of the track without rail. When elevation mismatch occurs in adjacent track slabs, a gasket should be placed at rail-bearing bed below the track slab in order to avoid the lower slab being dragged up by the higher slab and the further occurrence of new gap.

关键词： Ballastless track Rail Tracks lab CAmortar gap

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gap基含能热塑性弹性体的合成与表征

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火炸药学报 2014年第5期37卷 62-66页

作者：刘丽平黄振亚王鑫南京理工大学化工学院江苏南京210094

以聚叠氮缩水甘油醚(gap)为软段,1,4-丁二醇(BDO)和4,4′-二苯基甲烷二异氰酸酯(MDI)为硬段,采用熔融预聚体法合成了gap基含能热塑性弹性体(ETPE)。研究了扩链剂加料方式、催化剂用量、异氰酸酯指数、硬段含量等因素对弹性体力学性能的... 详细信息

以聚叠氮缩水甘油醚(gap)为软段,1,4-丁二醇(BDO)和4,4′-二苯基甲烷二异氰酸酯(MDI)为硬段,采用熔融预聚体法合成了gap基含能热塑性弹性体(ETPE)。研究了扩链剂加料方式、催化剂用量、异氰酸酯指数、硬段含量等因素对弹性体力学性能的影响。采用傅里叶变换红外光谱(FT-IR)、凝胶渗透色谱(GPC)、热台显微镜、差示扫描量热(DSC)、热重分析(TG)表征了ETPE的性能。结果表明,采用恒速滴加扩链剂方法合成的ETPE具有良好的热稳定性和力学性能。当催化剂质量分数为0.6‰,异氰酸酯指数(R)为0.98,硬段质量分数(Y)为35%时,热塑性弹性体的数均相对分子质量为52 312,软化点为96℃,拉伸强度为14.52MPa,断裂伸长率为518.78%。

关键词：有机化学聚叠氮缩水甘油醚含能热塑性弹性体含能黏合剂 gap ETPE

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Causes of maize density loss in farmers’ fields in Northeast China

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Journal of Integrative Agriculture 2019年第8期18卷 1680-1689页

作者： ZHAO Ying-jie XING Sen ZHANG Qing-song ZHANG Fu-suo MA Wen-qi Key Laboratory of Plant-Soil Interactions Ministry of Education Beijing 100193 P.R.China College of Resources and Environmental Sciences China Agricultural University Beijing 100193 P.R.China College of Resources and Environmental Science Hebei Agricultural University Baoding 071001 P.R.China

Increasing plant density is an effective and important way to reduce maize yield gaps in Northeast China. However, the fact is that a significant plant density gap exists between optimum plant density and actual plant density in farmers’ fields.To quantify the density gap between planned planting density and final harvest plant density(HPD), we studied 60 farmers’ fields on three types of soil for three crop seasons from 2015 to 2017 by measuring their plant-plant distance, actual seedlings density(ASD), final HPD and yield. We also explored the potential causes of density loss by digging the places where the seedlings were missing for two consecutive years in 2016–2017. Results show that the three-year average HPD in farmers’ fields was 59 699 plants ha^–1, which was significantly lower than the planned density, including both the machine setting density(MSD;67 962 plants ha^–1) and theoretical plant density(TPD;67 467 plants ha^–1). No significant difference was found in HPD between years and soil types. However, for MSD and TPD, the average value in 2015 was significantly higher than that in 2016 and 2017. No significant difference between soil types was observed. Furthermore,the results from 2016 till 2017 indicated that a lack of seeds in the soil, a failure to germinate due to low-quality seeds,and a lack of seedlings breaking out of the soil due to environmental problems explained approximately 60.88, 10.33 and 28.80% of density loss, respectively. According to our survey, 63% of farmers did not know their own TPD and HPD, and 54% of farmers did not know the density loss. Therefore, we argue that farmers’ limited knowledge of density and density loss is an urgent problem that needs to be solved in maize production. These observations will be useful for determining best management practices for maize production and for providing helpful suggestions for machine improvement.

关键词： plant density maize production density loss density gap farmers’ fields

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一类组合群论问题的研究

一类组合群论问题的研究

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作者：田开宇江苏大学

学位级别：硕士

本文考虑的是一个组合群论问题。设G是一个群,A={a1,a2,…,an}是G的一个n元子集,并且定义A2={ai| 1 ≤i,j ≤n}。若G是阿贝尔群,则显然有|A2|≤n(n+1)/2。如果对于有限群G的任意n元子集A,都有|A2|≤n(n+1)/2,则G被称为Bn群[1]。因此,Bn... 详细信息

本文考虑的是一个组合群论问题。设G是一个群,A={a1,a2,…,an}是G的一个n元子集,并且定义A2={ai| 1 ≤i,j ≤n}。若G是阿贝尔群,则显然有|A2|≤n(n+1)/2。如果对于有限群G的任意n元子集A,都有|A2|≤n(n+1)/2,则G被称为Bn群[1]。因此,Bn群可以看作是阿贝尔群的推广。在[2]中,Berkovich,Freiman和Praeger给出了小平方性质的定义:如果对于一个有限群G的任意n元子集A,|A2|gap,解决了一类B(n,k)群的刻画问题。特别地,本文给出了 B(6,22),B(6,23),B(6,24),B(7,29),B(7,30),B(8,36),B(8,37)和 B(9,45)群的描述,完善了 B(n,k)群的理论。

关键词： B(n,k)群 Bn群小平方性质 gap

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三磷酸甘油醛(gap)具有抑制多种植物病毒侵染的作用

三磷酸甘油醛(GAP)具有抑制多种植物病毒侵染的作用

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中国植物病理学会2023年学术年会

作者：左登攀刘玉姿陈政松胡汝检何梦君张宗英王颖王斌韩成贵中国农业大学植物病理学系农业农村部作物有害生物监测与绿色防控重点实验室

已有研究表明植物初级代谢途径在植物防御中发挥重要作用,植物防御反应的复杂系统需要大量的能量供应,这些能量主要来源于初级代谢过程。初级代谢相关基因下调所节省的能量可能被转移用于防御反应。初级代谢及其代谢产物在植物防御反应... 详细信息

已有研究表明植物初级代谢途径在植物防御中发挥重要作用,植物防御反应的复杂系统需要大量的能量供应,这些能量主要来源于初级代谢过程。初级代谢相关基因下调所节省的能量可能被转移用于防御反应。初级代谢及其代谢产物在植物防御反应中的作用,仍需要进行更多深入的研究来确定防御反应中涉及的相关组分及其分子机制。糖代谢作为初级代谢的核心,是植物重要的能量来源和重要有机物储存成分。糖作为信号分子参与植物昼夜变化、非生物和生物胁迫以及激素信号等协调植物新陈代谢和生长发育。在植物与病原物互作过程中,糖能提供防御反应所需的大部分能量并能作为信号分子调控植物免疫,在植物与病原物互作中发挥着越来越重要的作用。笔者实验室前期研究发现芸薹黄化病毒(BrYV)编码的移动蛋白(MP)在病毒侵染和致病过程中具有重要作用。利用MP筛选鉴定到与之互作的拟南芥叶绿体内膜丙糖磷酸转运器蛋白(TPT),BrYV侵染和转基因MP都能导致AtTPT转录水平和蛋白水平下调。遗传学试验结果表明TPT的过表达拟南芥植株显著提高了对BrYV的抗性,且TPT具有对多种病原菌的广谱抗性。进一步研究表明TPT的抗病毒功能可能依赖其底物转运能力,推测TPT的转运底物(gap等)在抗病中发挥重要作用。因此,利用注射浸润和喷施方法验证了只有gap能显著抑制多种植物病毒的侵染,如BrYV、芜菁花叶病毒(TuMV)、黄瓜花叶病毒(CMV)、马铃薯卷叶病毒(PLRV)和烟草花叶病毒(TMV)等,gap还能抑制丁香假单胞菌(Pseudomonas syringae pv.tomato DC 3000)和灰霉菌(Botrytis cinerea)的侵染。进一步利用转录组学和体外喷施实验分析发现,gap处理显著提高了植物防御相关基因和相关防御激素响应基因的表达,gap还能显著激活MAPK防御信号通路。本研究首次揭示了光合作用重要中间产物gap具有抗病毒和抗多种病原菌的作用,为深入研究gap发挥抗病作用的分子调控机制打下重要工作基础。

关键词：芸薹黄化病毒 gap 抑制病毒活性植物防御相关基因

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gap和GMP认证对泰国榴莲向中国出口的影响分析

GAP和GMP认证对泰国榴莲向中国出口的影响分析

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作者：陈慧东北财经大学

学位级别：硕士

随着经济的发展,人们越来越重视生活质量的提高,对于食品的品类和质量要求也不断提升。以榴莲为代表的泰国热带水果深受中国消费者欢迎,人们也更加重视水果的新鲜程度和口感。中国政府不断对进口产品尤其是进口水果采取高标准、严要求... 详细信息

随着经济的发展,人们越来越重视生活质量的提高,对于食品的品类和质量要求也不断提升。以榴莲为代表的泰国热带水果深受中国消费者欢迎,人们也更加重视水果的新鲜程度和口感。中国政府不断对进口产品尤其是进口水果采取高标准、严要求的管理措施,避免从任何国家和地区把不安全的产品、病害等带入中国。中国对所有原产于泰国的榴莲实施了 GMP认证和gap认证,对包括榴莲、山竹、龙眼、荔枝和芒果在内的5种进口水果实施重点检查。面对这种情况,泰国政府将采取何种态度来面对中国所要求的GMP和gap认证?泰国的榴莲生产商、种植农民又将以何种姿态来面对?泰国对中国的榴莲出口销售量会产生哪些影响?所有的这些问题对于探究贸易政策变化对出口方的影响有着重要意义,对泰中两国之间的贸易往来产生着深远又具有现实意义的影响。本文通过理论与实证分析,来回答这些问题并给出相应建议。首先,整理和总结了与主题相关的文献资料和新闻资讯,分析了技术性贸易壁垒对进出口的积极影响和消极影响。在短期时间内,技术性贸易壁垒会阻碍贸易的自由发展,但对于贸易长期发展十分有利。其次,阐述了泰国榴莲的种植、品种、质量,以及泰国种植者和出口商并没有十分重视gap和GMP认证的现实情况,导致gap与GMP在泰国认证覆盖率很低的状况。第三,利用双重差分(DID)模型与三重差分(DDD)模型预测实施gap和GMP认证后对泰国榴莲出口中国的变化。通过控制变量法对所得数据进行取样、分组、比较、分析,双重差分方法实证表明新的认证标准实行之后,泰国对华出口协议内水果额相比于非协议水果出口有了明显增加;三重差分方法实证检验结果表明相比于其它协议内水果而言,新认证标准的实行对榴莲出口的影响效果更大。最后,基于实证结果,本文以泰国种植者和出口商的角度建议:一是小农户合并升级,进行现代化管理,加速农业转型,提高核心竞争力;二是重视生产流程,把控环节细节,提高产品品质。从泰国政府的角度建议:一是推进泰国国内生产实名制,完善监督体制,使得产品有责可追;二是政府应该加强对农户的教育指导,增大宣传力度,提高群众意识;三是政府可运用大数据分析,公开产品最新走向,引导种植者和出口商生产更符合消费者的产品;四是政府需严格把控认证流程,保证gap与GMP证书的含金量,使得gap与GMP这两个证书成为消费者真正信任的标志。本文创新点主要分为两个方面:第一,研究内容上,本文从探讨gap和GMP认证对泰国榴莲出口的认证的基础上,深入研究在中国严格实行gap和GMP认证后,泰国榴莲出口到中国的变化数量及其所产生的影响,并以此研究结论为依据,对泰国政府、中国政府以及在进出口贸易过程中受到贸易影响的种植者、出口商和泰国政府提供适当的建议和措施,以便贸易交往中的各方都能够及时做出正确的措施,弥补技术性贸易壁垒在短期内造成的负面影响。第二,研究方法上,本文用计量方法实证研究gap和GMP认证有关的影响因素,并通过DID模型与DDD模型来分析实施gap和GMP认证后对泰国榴莲出口中国的影响因素变化,通过对控制变量法来对所得数据进行取样、分组、比较、分析。通过安慰剂检测以保证实证结果的稳健性和全面性。通过结合两个模型研究,得出新政策实行之后对于泰国出口榴莲的实际影响。

关键词：技术性贸易壁垒 gap GMP 榴莲出口

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