我国医疗器械产业集中度影响因素的实证研究

文章首先对我国医疗器械产业集中度进行测算,发现产业集中度呈持续上升态势.之后,采用线性回归分析和灰色关联分析对我国医疗器械产业集中度的影响因素进行分析.回归分析显示规模经济、生产企业进入率和股权投资有助于提高产业集中度,而产品差异率则阻碍了产业集中度的提高.灰色关联分析显示上述4种因素均对产业集中度具有重要影响,我国医疗器械产业集中度的变化是4种因素共同作用的结果.     

安徽省承接产业转移与创新产出的非均衡格局研究

优化承接产业转移和创新产出空间布局对充分发挥产业转移的创新效应具有重要意义.采用地理集中度、不一致指数、不均衡指数及回归分析等方法对2010—2016年安徽省承接产业转移与创新产出的空间格局及影响因素进行研究.结果表明:1)安徽省承接产业转移和创新产出地理集中度具有较强的一致性,皖江城市带的集中度都高,而皖西、皖北、皖南的大部分地区集中度低;2)安徽省大部分地市的产业转移集中度超前于创新产出集中度,皖江城市带除了合肥市、安庆市外以及皖西北大部分地区的不一致指数都呈上升趋势,皖西以及皖南大部分地区的不一致指数呈下降趋势;3)安徽省承接产业转移与创新产出的不均衡指数呈波动-稳定-明显上升的阶段特征;4)安徽省创新能力的提升主要依靠科技投入,但产业转移的溢出效应作用同样较显著.FDI、传统基础设施条件、科技人才、经济发展和科技政策的作用也相对较大,通讯基础设施水平和创新联系的作用较小.     

基于SSM-GIS的山西省资源型县域经济发展时空演变及发展机制研究

改革开放以来,资源型县域凭借资源优势和市场机遇,使得以煤炭资源为主要生产对象的第二产业迅速成为主导产业.本文运用变异系数、人均产值系数和偏离—份额分析等方法,对2005年~2015年山西省17个资源型县域总体经济和第二产业发展的时空演变格局进行分析.结果表明:(1)资源型县域经济呈现发展差异在波动中逐步扩大的趋势;(2)第二产业在山西省和全国产业发展水平中具有较高地位,相对优势明显;(3)空间上,第二产业专业化程度和产业集中度呈"火"字布局;(4)第二产业发展机制类型主要分为结构优化且竞争力增强型、结构优化但竞争力减弱型.     

产品市场竞争对资本结构的双维度影响机制研究——基于微观和中观视角

随着产品市场竞争会对资本结构产生影响这一观点逐渐被学术界所肯定,学者们发现企业自身具有的竞争优势与所处的行业环境都会对企业的资本结构决策行为产生影响。从微观(企业)层面和中观(产业)层面入手,分析企业市场势力、产业集中度以及二者的共同作用对资本结构决策的影响机理。研究发现:在垄断型行业,企业市场势力与负债水平呈负相关;在竞争型行业,企业市场势力与负债水平呈正相关。即产业集中度负向调节企业市场势力与资本结构的负向相关关系。因此,处于不同行业环境、竞争优势不同的企业要选择适合自己的负债水平,实施合理的竞争战略。     

环境能源约束下的中国石化产业全要素生产率Malmquist指数分析

在环境和能源因素约束的视角下,运用Malmquist指数法对中国石化产业的全要素生产率进行测算,探讨了中国石化产业全要素生产率,结果表明,在考虑了环境和能源因素后,2001-2010年我国石化产业全要素生产率的平均增长率为10.2％,主要原因是技术进步水平的提高;如不考虑能源和环境因素,石化产业的全要素生产率呈下降趋势,属于能源消耗和污染物排放较大的行业.     

1960—2011年秦岭南北地表干湿变化时空特征

运用P-M模型、气候倾向率及相关分析等方法,分析秦岭南北近52年地表干湿变化特征及其影响因素.结果表明:(1)潜在蒸散量(ET0)和干燥度指数(I)均呈现由南向北逐渐增加的空间分布型式;(2)ET0呈下降趋势,降速为-0.314mm/a(P0.05),其中1993年之前下降趋势显著,为-2.699mm/a(P0.01);(3)I呈缓慢上升趋势,增速为0.022/10a,在空间上呈现中部下降、两侧上升的分布型式,上升和下降趋势区域分别占62.62%和37.38%;(4)各年代干湿分界线变化显著,20世纪90年代最干旱,21世纪干燥程度有所缓解;(5)秦岭南北地表干湿状况及干湿分界线的变化主要归因于相对湿度、日照时数及降水量的变化.     

中国沿海集装箱港口集中度研究

利用行业集中度对我国沿海集装箱港口行业的市场结构演化过程进行分析.分析发现,近30年来,我国集装箱港口行业的市场结构由最初的寡占Ⅰ型发展到如今的寡占Ⅲ型,并且集中度有进一步下降的趋势,市场结构向寡占Ⅳ型发展.对比美国集装箱港口集中度发现,近10年来,我国集装箱港口集中度略高于美国,两国同属于寡占Ⅲ型的市场结构.但我国集装箱吞吐量是美国的3.59倍,我国前4位港口的平均集装箱吞吐量是美国的4倍,港口运输压力明显大于美国.过大的运输压力会给港口及其所在城市带来相应的负面影响.因此,在边缘挑战机制的作用下,我国沿海集装箱港口集中度有进一步下降的空间.     

中国煤炭产业集中度影响因素分析

在产业组织理论经典的SCP(结构-行为-绩效)分析范式中,市场结构通过影响市场行为,进而可以影响市场绩效.调整和改善不合理的市场结构是提高目标市场绩效的重要手段.产业集中度是重要的市场结构指标,它的变化的影响因素一直是产业经济学研究的重要内容.文章将产业组织理论和计量经济方法相结合,运用统计学相关方法及统计软件,对我国煤炭产业集中度的主要影响因素进行定量的实证分析,最终确立期初集中度、进入壁垒、市场容量、扩张能力等指标与煤炭产业集中度之间的数量关系,为制定我国煤炭产业又好又快发展的产业政策提供参考.     

边疆省区旅游经济系统脆弱性评价、影响因素及其应对策略——以云南省为例

以云南省16个市州为研究单元,运用综合指数法及障碍度模型探究2004-2016年云南省各市州旅游经济系统脆弱性的时空格局演变特征及其影响因素.结果表明:(1)2004-2016年云南省各市州旅游经济系统脆弱性总体呈下降趋势,其绝对差异与相对差异均呈波动下降态势;(2)旅游经济系统脆弱性空间分布格局日益均衡,高脆弱性市州空间集聚态势明显,"核心—边缘"式空间结构逐渐形成,低脆弱性市州呈现"趋同俱乐部"空间态势,边境市州脆弱性低于内陆市州;(3)云南省六大旅游区旅游经济系统脆弱性均呈下降趋势,其中以滇西北下降幅度最大,滇东北与滇东南下降幅度较小;(4)敏感性对旅游经济系统脆弱性发挥主导作用,其应对能力的主要制约因素是基础设施建设滞后与区域经济对外开放程度偏低.     

河南省承接产业转移与环境污染非均衡格局研究

采用地理集中度、不一致指数、不均衡指数及回归分析等方法对2007—2016年河南省承接产业转移与环境污染的时空格局演变及影响因素进行研究.结果表明,河南省承接产业转移的空间分布总体趋向集中,具有明显的边缘-核心结构,市域差异显著;与产业转移集聚格局不同,河南省环境污染集中度时空格局变化较明显,由"西北高东南低"演变为"北高南低"的空间格局;整体来说,河南省大部分地区以环境污染集聚超前于产业转移集聚为主,而产业转移集聚相对超前的市域主要分布在豫东地区,产业转移集聚与环境污染集聚基本一致的地区由2个增加到7个,二者一致性越来越显著,且在空间分布上有向南推进的趋势;河南省2007—2016年承接产业转移与环境污染分布的不均衡指数均为正数,且呈波动下降趋势,由2007年的0.029 5下降到2016年的0.024 0,二者集聚格局有趋同态势,相关性日益显著;对环境污染影响最大且是正向影响的因素为能源消费量,规模以上工业企业RD人员数、专利数的回归系数都为负值,表明加快河南省工业企业能源消费类型转型.加大人才资本、技术的引进力度,着力改善各行业生产技术是促进河南省承接产业转移与环境状况协调发展的关键.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.