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生产性服务业集聚一定会提升制造业的生产率吗?--来自微观企业的证据

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产经评论 2017年第6期8卷 70-80页

作者：黎日荣周政浙江树人大学浙江省现代服务业研究中心

制造业依然有进一步向城市集聚的趋势,生产性服务业集聚如何提高企业的生产效率需要更深入的研究。在什么条件下集聚才能避免拥挤效应,从而有效地提高集聚效应,对此,现有文献尚未作出很好的解释。对不同空间尺度下生产性服务业的溢出效... 详细信息

制造业依然有进一步向城市集聚的趋势,生产性服务业集聚如何提高企业的生产效率需要更深入的研究。在什么条件下集聚才能避免拥挤效应,从而有效地提高集聚效应,对此,现有文献尚未作出很好的解释。对不同空间尺度下生产性服务业的溢出效应,可使用中国220个地级及以上城市的工业企业数据进行分析。与已有文献普遍认为的生产性服务业集聚会提升制造业生产率不同,研究发现生产性服务业集聚的溢出效应在不同空间单元表现不同,在全市范围表现为显著的集聚效应,每平方公里增加100个生产性服务就业人口,企业的平均生产率提升19.52%;在市辖区表现为显著的拥挤效应,每平方公里增加100个生产性服务就业人口,企业的平均生产率下降19.87%。这表明只有与集聚区保持适度的距离才能更好地发挥集聚效应。通过分析不同规模城市发现,集聚效应只显著发生在生产性服务业高度集聚的大城市,说明生产性服务业要集聚到一定程度才显著发挥外溢作用。结论的政策含义是:地级市政府宜提高辖市辖县与辖区之间的交通便利性,辖市辖县专业发展制造业,以接受市辖区生产性服务业的集聚效应。

关键词：制造业生产性服务业集聚企业生产率集聚效应拥挤效应

Diffusion tensor imaging of the hippocampus reflects the severity of hippocampal injury induced by global cerebral ischemia/reperfusion injury

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Neural Regeneration Research 2022年第4期17卷 838-844页

作者： Wen-Zhu Wang Xu Liu zheng-Yi Yang Yi-zheng Wang Hai-Tao Lu China Rehabilitation Science Institute School of Rehabilitation MedicineCapital Medical UniversityBeijing Bo’ai HospitalChina Rehabilitation Research CenterBeijingChina Beijing Key Laboratory of Neural Injury and Rehabilitation BeijingChina Department of Rehabilitation Medicine Beijing Friendship HospitalCapital Medical UniversityBeijingChina Brainnetome Center Institute of AutomationChinese Academy of SciencesBeijingChina

At present,predicting the severity of brain injury caused by global cerebral ischemia/reperfusion injury(GCI/ri)is a clinical *** such an injury,clinical indicators that can directly reflect neurological dysfunction are *** change in hippocampal microstructure is the key to memory formation and *** tensor imaging is a highly sensitive tool for visualizing injury to hippocampal *** hippocampal microstructure,brain-derived neurotrophic factor(BDNF),and tropomyosin-related kinase B(Trk B)levels are closely related to nerve injury and the repair process after GCI/ri,whether these indicators can reflect the severity of such hippocampal injury remains *** address this issue,we established rat models of GCI/ri using the four-vessel occlusion *** tensor imaging parameters,BDNF,and Trk B levels were correlated with modified neurological severity *** results revealed that after GCI/ri,while neurological function was not related to BDNF and Trk B levels,it was related to hippocampal fractional *** findings suggest that hippocampal fractional anisotropy can reflect the severity of hippocampal injury after global GCI/*** study was approved by the Institutional Animal Care and Use Committee of Capital Medical University,China(approval ***-2015-139)on November 9,2015.

关键词： brain-derived neurotrophic factor diffusion tensor imaging fractional anisotropy value global cerebral ischemia/reperfusion injury hippocampus Trk B

消费税收入分配机制调整:法理检视与实现路径

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税务与经济 2019年第1期 93-100页

作者：郑日晟武汉大学法学院湖北武汉430074

"营改增"后,消费税收入分配机制调整对于化解地方政府财政困难具有积极意义。但是,消费税收入分配机制的调整还需要从税制功能、税法原则和征管效率三个方面进行法理论证,并在此基础上进行制度设计,以更好地实现消费税的改革目标与制度... 详细信息

"营改增"后,消费税收入分配机制调整对于化解地方政府财政困难具有积极意义。但是,消费税收入分配机制的调整还需要从税制功能、税法原则和征管效率三个方面进行法理论证,并在此基础上进行制度设计,以更好地实现消费税的改革目标与制度功能,体现财税体制改革的合法性与合理性、公平性与效率性、形式法治与实质法治之统一。在消费税收入分配机制改革的模式选择上,我国不宜对消费税采取中央税模式或地方税模式,而应采取"税基分享"的共享税模式,这有利于协调消费税制的不同功能,体现受益原则,提高税收征管效率,激励政府改善消费环境。在这一前提下,未来的消费税制设计还应统筹兼顾,处理好消费税收入分配机制改革与其他消费税改革措施的衔接关系。

关键词：营改增消费税收入分配税收收益权税制改革

Long Period Grating Imprinted on a Flat-Shaped Plastic Optical Fiber for Refractive Index Sensing

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Photonic Sensors 2023年第4期13卷 39-49页

作者： Yuan LIU Yanfei ZHOU Haiyang BAO Jie zheng State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun 130012China

A corrugated surface long period grating(LPG)was fabricated on a flat-shaped plastic optical fiber(POF)as a refractive index(ri)sensor by a simple pressing with the heat pressure and mechanical die press print *** light propagation characteristics of an LPG imprinted on a multi-mode POF were analyzed by the method of geometrical *** and experimental results showed that the structural parameters of the sensor affected the ri sensing performance,and the sensor with a thinner flat thickness,a deeper groove depth of the corrugated surface LPG,and a longer LPG exhibited better ri sensing *** the POF with a diameter of 1 mm was pressed with the heat pressure to a flat shape with a thickness of 600μm,an LPG with a period of 300μm,a groove depth of 200μm,and a length of 6 cm was fabricated on it,and the ri sensitivity of 1447%/riU was obtained with a resolution of 5.494×10^(−6) *** addition,the influences of the POF cladding,tilting of LPG,and bending of the sensing structure were *** results demonstrated that after removing the cladding and tilting or bending the LPG,the ri sensing performance was *** the LPG imprinted on the flat-shaped POF was bent with a curvature radius of 6/πcm,the highest sensitivity of 6563%/riU was achieved with a resolution of 2.487×10^(−9) riU in the ri range of 1.3330–*** proposed sensor is a low-cost solution for ri measurement with the features of easy fabrication,high sensitivity,and intensity modulation at the visible wavelengths.

关键词： Plastic optical fiber fiber optic sensor flat-shaped optical fiber long period grating refractive index sensing

Analysis of aroma-active compounds in three sweet osmanthus(Osmanthus fragrans) cultivars by GC-olfactometry and GC-MS

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2014年第7期15卷 638-648页

作者： Xuan CAI Rong-zhang MAI Jing-jing ZOU Hong-yan ZHANG Xiang-ling ZENG ri-ru zheng Cai-yun WANG Key Laboratory of Horticultural Plant Biology Ministry of Education Huazhong Agricultural University Guangxi Communications Investment Group Yulin Expressway Operation Co. Ltd.

Objective：Aroma is the core factor in aromatherapy. Sensory evaluation of aromas differed among three sweet osmanthus （Osmanthus fragrans） cultivar groups. The purpose of this study was to investigate the aroma-active compounds responsible for these differences. Methods： Gas chromatography-olfactometry （GC-O） and GC-mass spectrometry （GC-MS） were used to analyze the aroma-active compounds and volatiles of creamy-white （‘Houban yingui’, HBYG）, yellow （‘Liuye Jingui’, LYJG）, and orange （‘Gecheng Dangui’, GCDG） cultivars. Results：Seventeen aroma-active compounds were detected among 54 volatiles. trans-β-Ocimene, trans-β-ionone, and linalool, which were major volatiles, were identified as aroma-active, while cis-3-hexenyl butanoate,γ-terpinene, and hexyl butanoate were also aroma-active compounds, although their contents were low. Analysis of the odors was based on the sum of the modified frequency （MF） values of aroma-active compounds in different odor groups. HBYG contained more herb odors, contributed by cis-β-ocimene and trans-β-ocimene, while LYJG had more woody/violet/fruity odors released by trans-β-ionone, α-ionone, and hexyl butanoate. In GCDG, the more floral odors were the result of cis-linalool oxide, trans-linalool oxide, and linalool. Conclusions：Aroma-active compounds were not necessarily only the major volatiles：some volatiles with low content also contributed to aroma. The aroma differences among the three cultivars resulted from variation in the content of different odor groups and in the intensities of aroma-active compounds.

关键词： Gas chromatography-olfactometry (GC-O) Gas chromatography-mass spectrometry (GC-MS) Aroma Sweet osmanthus ( Osmanthus fragrans)

Enforcing Strong Stability of Explicit Runge-Kutta Methods with Superviscosity

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Communications on Applied Mathematics and Computation 2021年第4期3卷 671-700页

作者： zheng Sun Chi-Wang Shu Department of Mathematics The Ohio State UniversityColumbusOH 43210USA Division of Applied Mathematics Brown UniversityProvidenceRI02912USA

A time discretization method is called strongly stable(or monotone),if the norm of its numerical solution is *** this property is desirable in various of contexts,many explicit Runge-Kutta(RK)methods may fail to preserve *** this paper,we enforce strong stability by modifying the method with superviscosity,which is a numerical technique commonly used in spectral *** main focus is on strong stability under the inner-product norm for linear problems with possibly non-normal *** propose two approaches for stabilization:the modified method and the filtering *** modified method is achieved by modifying the semi-negative operator with a high order superviscosity term;the filtering method is to post-process the solution by solving a diffusive or dispersive problem with small *** linear problems,most explicit RK methods can be stabilized with either approach without accuracy ***,we prove a sharp bound(up to an equal sign)on diffusive superviscosity for ensuring strong *** nonlinear problems,a filtering method is *** examples with linear non-normal ordinary differential equation systems and for discontinuous Galerkin approximations of conservation laws are performed to validate our analysis and to test the performance.

关键词： Runge-Kutta(RK)methods Strong stability Superviscosity Hyperbolic conservation laws Discontinuous Galerkin methods

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宠物与儿童社会情绪的关系

中国心理卫生杂志 2007年第11期21卷 804-808页

作者：周霞郑日昌傅纳北京师范大学心理学院北京100875 北京师范大学教育学院北京100875

目的：研究宠物对儿童社会情绪的影响。方法：用自编问卷对197名养宠物犬的儿童及其家长和205名不养宠物的儿童及其家长进行调查。结果：养宠物犬的儿童与不养宠物的儿童在社会情绪三个指标上的差异有统计学显著性：相比不养宠物的儿童... 详细信息

目的：研究宠物对儿童社会情绪的影响。方法：用自编问卷对197名养宠物犬的儿童及其家长和205名不养宠物的儿童及其家长进行调查。结果：养宠物犬的儿童与不养宠物的儿童在社会情绪三个指标上的差异有统计学显著性：相比不养宠物的儿童，养宠物犬的儿童孤独感更少（x^2=39．15，P〈0．001），其报告单独在家感到孤独的占12．0％，不感到孤独的占80．2％，而不养宠物的儿童分别为38．7％、52．2％；养宠物犬的儿童分享倾向更强（x^2=8．20，P=0．017），其报告非常愿意和他人分享的占82．2％，只和喜欢的人分享的占14．7％，不愿意分享的占3．1％，而不养宠物的儿童分别为72．8％、25．7％、1．5％；养宠物犬的儿童更愿意照顾幼小儿童（x^2=25．88，P〈0．001），其报告非常愿意照顾他人的占40．1％，愿意的占49．7％，不愿意的占10．2％，而不养宠物的儿童分别为23．7％、47．4％、28．9％。此外，儿童与宠物亲密程度的诸多指标与分享倾向及照顾幼小儿童倾向正相关（r=0．17—0．35，P〈0．05或P〈0．01或P〈0．001）。与孤单感倾向负相关（r=-0．20--0．23，P均〈0．01）。结论：宠物与儿童社会情绪的发展之间存在某种联系，值得重视，应进行更深入的研究。

关键词：儿童心理社会情绪横断面调查宠物

环氧丁羟/蒙脱土增韧改性环氧树脂包覆层的制备及性能研究

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火炸药学报 2021年第3期44卷 349-355页

作者：肖然丛日敏丁政茂罗运军北京理工大学材料学院北京100081 高能量密度材料教育部重点实验室北京100081

为了对环氧树脂(EP)包覆层进行增韧改性,用环氧丁羟(EHTPB)剥离有机蒙脱土(OMMT),制成EHTPB/OMMT纳米复合增韧剂引入到环氧树脂体系中;通过傅里叶变换红外光谱(FTIR)、低场核磁(LF-NMR)、扫描电镜(SEM)、静态力学性能测试等,对改性环氧... 详细信息

为了对环氧树脂(EP)包覆层进行增韧改性,用环氧丁羟(EHTPB)剥离有机蒙脱土(OMMT),制成EHTPB/OMMT纳米复合增韧剂引入到环氧树脂体系中;通过傅里叶变换红外光谱(FTIR)、低场核磁(LF-NMR)、扫描电镜(SEM)、静态力学性能测试等,对改性环氧树脂包覆层的结构、增韧机理和力学性能进行了研究,测试了OMMT与EP质量比为0.2∶100样品的抗烧蚀性能和黏结性能。结果表明,当OMMT与EP质量比为0.2∶100时,EHTPB/OMMT/EP包覆层的弹性模量比空白样品降低184.61%,断裂伸长率提高287.55%;线烧蚀率为0.155mm/s,黏结强度为3.84MPa。分析认为,由于EHTPB为环氧树脂基体引入了大量橡胶柔性分子链,而OMMT片层结构能有效进行应力的传递,使体系吸收更多的断裂能,有效阻碍产生的微裂纹的扩散;且OMMT与EP、EHTPB分子链间通过氢键形成交联网络,提高了韧性。

关键词：材料科学环氧丁羟蒙脱土环氧树脂增韧改性

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冲压发动机-飞行器加速过程轨迹最优化研究

推进技术 2017年第8期38卷 1754-1760页

作者：杨晟博郑日升于达仁哈尔滨工业大学能源科学与工程学院黑龙江哈尔滨150001 北京电子工程总体研究所北京100084

为了研究吸气式飞行器加速过程的最优轨迹,针对一个以冲压发动机为动力的超声速飞行器,由起始状态19km(约2.7马赫)至终点状态25km(约6.0马赫)的加速爬升过程,提出了一种考虑发动机推进机理的加速过程轨迹最优化方法。将理想的冲压发动... 详细信息

为了研究吸气式飞行器加速过程的最优轨迹,针对一个以冲压发动机为动力的超声速飞行器,由起始状态19km(约2.7马赫)至终点状态25km(约6.0马赫)的加速爬升过程,提出了一种考虑发动机推进机理的加速过程轨迹最优化方法。将理想的冲压发动机模型与竖直平面飞行器动力学模型相结合,考虑不启动保护约束,分别定义了最小油耗和最小时间两种轨迹最优化问题,并应用高斯伪谱法进行求解。结果表明,轨迹最优化问题的实质是将发动机比冲和推力性能与飞行器动力学性能进行最优化匹配。最小油耗轨迹较最小时间轨迹增加了30.3%的加速时间,节约了4.7%的燃油消耗。不同的起飞重量对最小油耗轨迹有一定的影响,较大的起飞重量需要飞行器在爬升前获得更大的动压。

关键词：冲压发动机轨迹优化高斯伪谱法最小时间轨迹最小油耗轨迹