不同过滤条件下黄色物质的吸收光谱演化特征分析          下载免费PDF全文

吴永森  吴绍渊  魏然  张耀立 《海洋与湖沼》2008,39(6):585-590

在实验室对青岛近岸现场水样进行处理、分析，获得了原始状态下水样和被过滤（0.22μm,0.45μm）黄色物质水样的吸收光谱数据，除进一步验证了黄色物质光谱分布模式外，还测得黄色物质光吸收随滤膜孔径的变化。30个现场样品在波长380nm处吸收系数统计平均值^—Ay（380）分析表明，当使用0.45μm过滤器对水样进行处理，所获得的^—Ay（380）值要比未经过处理的现场水样所测得的^—Ay（380）值高约2.1％；而用0.22μm过滤器对现场水样进行处理，所获得的^—Ay（380）值要比未经过处理的现场样品所测得的^—Ay（380）值高约12．6％，要比用0．45μm过滤器处理的现场样品所测得的^—Ay（380）值高约10.3％，这些数据的获得为现有已获黄色物质数据的“归一化”和统一评判以及未来黄色物质测量数据的准确性判断与比较提供了参考。  相似文献   

Wind impact on pollutant transport in a shallow estuary   总被引：4，自引：0，他引：4  

XU Hongzhou  LIN Jing  SHEN Jian  WANG Dongxiao 《海洋学报(英文版)》2008,27(3):147-160

A three-dimensional numerical model, EFDC （ environmental fluid dynamics code） is applied to the Pamlico River Estuary （PRE） in eastern North Carolina of the United States to examine the wind impact on pollutant age distributions and residence time. A series of model experiments representing base case, remote-wind-induced water level set-up and local winds cases are conducted. Model results indicate that the pollutant mean age and the system residence time are functions of gravitational circulation in the PRE. The system responses to remote-wind-induced water level set-up are different in different portions of the PRE. Under such condition, dissolved substances in the upstream portion of the PRE have a younger age and shorter residence time （compared with the base case） , by contrast, they have a older age and longer residence time in the downstream portion of the PRE. Upriver and downriver local winds appear to have opposite impacts on pollutant age distributions. The substances are retained much longer within the PRE under upriver wind than those under downriver wind. The model results also suggest that across - river winds may lead to longer residence time through enhanced turbulence mixing, which slows down the gravitational circulation in the PRE.  相似文献   

中国中部地区技术关联对产业创新的影响研究     

郝均  曾刚  赵建吉  胡志强 《地理研究》2020,39(3):601-610

技术关联对地区产业创新和经济增长具有重要影响。本文从演化经济地理学认知邻近的视角出发,借助中部地区制造业企业数据和专利数据,运用技术关联分析方法,探究制造业四位数行业技术关联对产业创新的影响机制。结果表明：随着时间的推移,技术关联对创新能力较弱的中部地区产业创新的促进作用越来越强;对于资源型产业集中、经济发展前景不佳的山西省而言,技术关联的作用并不显著;技术关联对其他五省制造业创新具有正向作用,呈现中间强南北弱的空间格局;从产业门类看,技术关联对技术密集型产业创新促进作用最强,劳动密集型产业次之,资源密集型产业靠后,资本密集型产业最弱。  相似文献   

苹果手机零部件全球价值链的价值分配与中国角色演变   总被引：1，自引：2，他引：1  

康江江  张凡  宁越敏 《地理科学进展》2019,38(3):395-406

产品内分工已成为支配当代企业分工与产品生产的重要模式。研究智能手机生产网络价值分配格局,对辨析中国大陆企业在移动通讯产业价值链中所处地位与演进具有重要意义。论文利用2012—2017年苹果公司供应商数据,以其零部件价值含量与技术要求为测度标准,分析了苹果手机零部件全球价值链的分配特征以及中国大陆企业在其中的地位变化。发现：高价值环节的供应商主要以美国、日本、韩国为主,而中低价值环节则以中国台湾、日本和中国大陆供应商为主,且中国大陆与中国台湾在中间环节占据重要地位。处于价值链高端的供应商分支数量在中国大陆和美国缩减明显,日本、韩国较为稳定,中国台湾增加明显。在价值链的中低端环节,供应商分支趋向中国大陆集中。印度、巴西以及越南等地成为新的中低端价值环节转移承接地。近年来,中国大陆在苹果手机价值链的高端环节得到了提升,长三角、珠三角、京津冀、成渝、中原地区等地逐渐形成了苹果供应商分支的集聚区域,呈现出零部件生产的区域分工特征。长三角(上海-苏州为核心)与珠三角(深圳-东莞为核心),承接了价值链多个生产环节,是中国大陆嵌入苹果手机生产网络的主要阵地。成渝地区既承接了芯片类企业布局,也承接了价值链低端的组装代工和包装服务环节,呈现出在价值链两端双向承接的特征。环渤海、福建及湖南等地主要承接苹果手机价值链的中间环节,而中原地区主要以苹果手机组装与包装服务为主,承接价值链的低端环节。最后,论文从创新驱动、政府作用与外资等方面探讨了影响中国大陆地位提升的因素。  相似文献   

Wavelet analysis and nonparametric test for climate change in Tarim River Basin of Xinjiang during 1959–2006     

Jianhua Xu  Yaning Chen  Weihong Li  Minhe Ji  Shan Dong  Yulian Hong 《中国地理科学(英文版)》2009,19(4):306-313

Using wavelet analysis, regression analysis and the Mann-Kendall test, this paper analyzed time-series (1959–2006) weather data from 23 meteorological stations in an attempt to characterize the climate change in the Tarim River Basin of Xinjiang Uygur Autonomous Region, China. Major findings are as follows: 1) In the 48-year study period, average annual temperature, annual precipitation and average annual relative humidity all presented nonlinear trends. 2) At the 16-year time scale, all three climate indices unanimously showed a rather flat before 1964 and a detectable pickup thereafter. At the 8-year time scale, an S-shaped nonlinear and uprising trend was revealed with slight fluctuations in the entire process for all three indices. Incidentally, they all showed similar pattern of a slight increase before 1980 and a noticeable up-swing afterwards. The 4-year time scale provided a highly fluctuating pattern of periodical oscillations and spiral increases. 3) Average annual relative humidity presented a negative correlation with average annual temperature and a positive correlation with annual precipitation at each time scale, which revealed a close dynamic relationship among them at the confidence level of 0.001. 4) The Mann-Kendall test at the 0.05 confidence level demonstrated that the climate warming trend, as represented by the rising average annual temperature, was remarkable, but the climate wetting trend, as indicated by the rising annual precipitation and average annual relative humidity, was not obvious.  相似文献   

Historic changes in flux of matter and nutrient budgets in the Bohai Sea   总被引：1，自引：0，他引：1  

LIU Sumei  ZHANG Jing  GAO Huiwang  LIU Zhe 《海洋学报(英文版)》2008,27(5):81-97

Over the past four periods （ 1959--1960, 1982--1983, 1992--1993, and 1998--1999）, the ecosystem of the Bohai Sea changed due to both a significant decrease of river water discharge from the Huanghe River and a reduction of precipitation. The shifts in nutrient chemistry could result in changes in the phytoplankton composition with an increased potential for non-diatom algal blooms. Simple box model was used to estimate the water - mass balance and nutrient budgets for the Bohai Sea. Water budgets indicate that the residual flow changed from out of the Bohai Sea before 1993, but became inflow to the Bohai Sea after then. The nutrient budgets developed indicate that the Bohai Sea was a sink for nutrients except for phosphate in 1959--1960 and 1982-- 1983 and for silicate in 1982--1983. Net water flow transports nutrients out of the Bohai Sea in 1959--1960, 1982--1983 and 1992--1993, but into the sea in 1998--1999 due to climate changes, such as precipitation and subsequent freshwater discharge. The residual fluxes of nutrients are minor relative to atmospheric deposition and riverine inputs. Conversions of phosphate values to carbon by stoichiometric ratios were used to predict that the system was net heterotrophic before 1982--1983 and net autotrophic after then. Nutrient budgets can explain the change of nutrient concentrations in the Bohai Sea except nitrates, which should include the surface runoff.  相似文献   

Benthic nutrient recycling in shallow coastal waters of the Bohai Sea   总被引：3，自引：0，他引：3  

刘素美张经  陈洪涛T.Raabe 《中国海洋湖沼学报》2004,22(4):365-372

Sediment-water fluxes of N and P species in the Bohai Sea were investigated in September-October 1998 and April-May 1999. The benthic fluxes of nutrient species were determined by incubating sediment core samples with bottom seawater bubbled with air or nitrogen. NO^-2,NH4, dissolved organic nitrogen (DON) and phosphorus (DOP), total dissolved nitrogen (TDN) and phosphorus (TDP), and PO4^3- showed a net exchange flux from seawater to sediment, while NO^-3, dissolved inorganic nitrogen (DIN) and SiO3^2- were released from sediment to seawater in the Bohai Sea. Sediment-water nutrient exchange increases DIN and reduces the phosphorus load in the Bohai Sea. The release of silicate from sediment to overlying seawater reduces potential silicate limitation of primary production resulted from decrease of riverine discharge.The exchange flux of nutrients showed no obvious seasonal variation. The present study showed that the concentrations and composition of nutrients in the water column were affected by suspended sediment, and that not all the exchangeable phosphate in sediment could be released via sediment resuspension.  相似文献   

�ռ�����ؾֲ�ָ��Moranָ����Gϵ���о�   总被引：15，自引：0，他引：15  

张松林  张昆 《大地测量与地球动力学》2007,27(3):31-34

?о????????????????????????????Moran?????G???????????????????????Щ?д?????????????????м??????????????????????ó????G?????????Moran?????????  相似文献   

跨区域产业技术关联与产业创新——基于中国制造业的分析   总被引：1，自引：1，他引：1  

钱肖颖  孙斌栋 《地理科学进展》2020,39(11):1822-1831

产业分工联系是区域一体化的基础,但已有产业技术关联的文献主要关注区域内部,缺乏对跨区域产业技术关联的探究。由于中国省际产业联系数据难以获取,论文运用引力模型和交叉熵法,基于2002、2007、2012年30省的投入产出表拟合出省际产业贸易流量矩阵,并进一步计算跨区域产业技术关联指数。跨区域产业技术关联呈现不断加强的趋势,尤其是城市群内部各地区产业之间的联系。基于2002、2007、2012年中国30个省16个制造业部门的面板数据,使用固定效应模型进一步考察了跨区域产业技术关联对产业创新的影响。结果发现,跨区域产业技术关联有利于区域产业创新,但在本地产业技术联系较强的地区,跨区域产业技术关联对产业创新的正效应会被削弱,本地产业技术关联和省际产业技术关联之间存在“替代效应”,知识产权的地方保护主义是导致这一结果的可能原因。因此,政策上应倡导扫清制度障碍、完善知识产权保护制度,促进跨区域产业对本地的技术溢出,进一步推动区域产业创新。  相似文献   

中资企业研发国际化研究述评   总被引：2，自引：0，他引：2  

司月芳  延留霞  张翌 《地理研究》2020,39(5):1056-1069

中资跨国公司研发国际化服务于中国"全面提高开放型经济水平"和"创新驱动发展战略"两大政策方针,是重要的地理学研究前沿。本文系统评述了中资企业研发国际化的定义、理论基础、研究内容、数据和方法,发现基于发达国家跨国公司实践建立起的经典理论还不足以解释中资企业行为。相比于快速发展的中资企业跨国研发活动行为,现有的实证研究存在着研究视角、内容和方法的局限,未来应发扬地理学多尺度研究的优势,综合分析企业研发国际化与区域发展的互动机制;发扬地理学重视区域差异的优势,开展在"一带一路"国家中资企业研发国际化的异质性研究;发扬地理学重视实地调研的优势,综合多种方法和数据的相互印证。  相似文献