检索结果-南通市图书馆

Temporal and spatial distribution of dissolved copper,lead,zinc and cadmium in the Changjiang Estuary and its adjacent waters

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2008年第4期27卷 73-82页

作者： wang changyou wang Xiulin wang Baodong ZHANG Chuansong SHI Xiaoyong ZHU Chenjian College of Chemistry ＆ Chemical Engineering Ocean University of China Qingdao 266100 China First Institute of Oceanography State Oceanic Administration Qingdao 266061 China

Heavy metal concentrations were measured in the Changjiang Estuary and its adjacent waters. Results from a systematic survey in April 2002 to March 2003 indicate that the ranges of the concentrations of dissolved copper, lead, zinc and cadmium in the study waters are 1.01 - 6.86, 0. 10 - 0.39,3.17 - 9.12 and 0.011 - 0. 049 μg/dm^3 , respectively. Similar to zinc, the behavior of dissolved copper was essentially conservative, but high scatter has been observed for high salinity samples, which can be attributed to the decomposition or mineralization of organic matter by bacteria. Dissolved lead may have active behavior with an addition at high salinity. Overall concentrations of dissolved cadmium increase with salinity. The mean values of these dissolved metals calculated for the surface waters were higher than those for the middle and bottom ones. External inputs of dissolved heavy metals to the surface waters were the likely explanation for these higher values. The maximum seasonal average values of dissolved copper and zinc were found in summer, reflecting higher amounts of riverine input in this season. In contrast, the maximum seasonal average values of dissolved lead and copper were found in winter and the lowest ones in summer, respectively, which might be asso- ciated with a combination of low concentration with heterogeneous scavenging. Concentrations of these dissolved metals found for the Changjiang Estuary fall in the range observed for the other estuaries but are noticeably higher than those from uncontaminated rivers, except for cadmium. Compared with observations for the Changjiang Estuary in the last two decades, it is clear that the Changjiang estuarine waters has been contaminated with copper, lead, zinc and cadmium during China＇ s industrialization, but concentrations of them have decreased in the last few years.

关键词： heavy metals distribution biological activity East China Sea Changjiang Estuary

On a delay ratio-dependent predator-prey system with feedback controls and shelter for the prey

在线全文

学校读者我要写书评

暂无评论

International Journal of Biomathematics 2018年第7期11卷 287-316页

作者： changyou wang Linrui Lit Yuqian Zhou Rui Li College of Applied Mathematics Chengdu University of Information Technology Chengdu Sichuan 610225P.R.China Basic Courses Department Institute of Disaster Prevention SanheHebei 065201P.R.China College of Automation Chongqing University of Posts and Telecommunzcations Chongqing 400065 P.R.China

In this paper,a class of three-species multi-delay Lotka-Volterra ratio-dependent predator-prey model with feedback controls and shelter for the prey is considered.A set of easily verifiable sufficient conditions which guarantees the permanence of the system and the global attractivity of positive solution for the predator-prey system are established by developing some new analysis methods and using the theory of differentim inequalities as well as constructing a suitable Lyapunov ***,some conditions for the existence,uniqueness and stability of positive periodic solution for the corresponding periodic system are obtained by using the fixed point theory and some new analysis *** addition,some numerical solutions of the equations describing the system are given to show that the obtained criteria are new,general,and easily ***,we still solve numerically the corresponding stochastic predator-prey models with multiplicative noise sources,and obtain some new interesting dynamical behaviors of the *** the same time,the influence of the delays and shelters on the dynamics behavior of the system is also considered by solving numerically the predator-prey models.

关键词： Predator-prey model feedback control delay permanence attractive periodic solution

On the Uniqueness of Heat Flow of Harmonic Maps and Hydrodynamic Flow of Nematic Liquid Crystals

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2010年第6期31卷 921-938页

作者： Fanghua LIN changyou wang Courant Institute of Mathematical Sciences New York University New York NY 10012 USA Department of Mathematics University of Kentucky Lexington KY 40506 USA.

For any n-dimensional compact Riemannian manifold (M,g) without boundary and another compact Riemannian manifold (N,h), the authors establish the uniqueness of the heat flow of harmonic maps from M to N in the class C([0,T),W1,n). For the hydrodynamic flow (u,d) of nematic liquid crystals in dimensions n = 2 or 3, it is shown that the uniqueness holds for the class of weak solutions provided either (i) for n = 2, u ∈ Lt∞ L2x∩L2tHx1, ▽P∈ Lt4/3 Lx4/3 , and ▽d∈ L∞t Lx2∩Lt2Hx2; or (ii) for n = 3, u ∈ Lt∞ Lx2∩L2tHx1∩ C([0,T),Ln), P ∈ Ltn/2 Lxn/2 , and ▽d∈ L2tLx2 ∩ C([0,T),Ln). This answers affirmatively the uniqueness question posed by Lin-Lin-wang. The proofs are very elementary.

关键词： Hydrodynamic flow Harmonic maps Nematic liquid crystals Uniqueness

Role of Resuspended Sediments as Sources of Dissolved Inorganic Phosphorus Along Different Dimensions in the Subei Shoal, South Yellow Sea, China

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2023年第1期22卷 161-170页

作者： wang changyou ZHENG Ping SU Rongguo LUO Zhuhua ZHANG Yuanzhi MAO Longjiang School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationOcean University of ChinaQingdao 266100China Key Laboratory of Marine Biogenetic Resources Third Institute of OceanographyMinistry of Natural ResourcesXiamen 361005China

Several studies have documented that during‘green tide’events,comprising green macroalgae blooms in aquatic ecosystems,dissolved inorganic phosphorus(DIP)levels remain relatively steady despite the absorption of a large amount of *** this study,surface sediment samples and a sediment core were extracted using a modified sequential extraction scheme,and water and surface sediment samples were analyzed in April 2017 to better understand phosphorus(P)cycling and replenishment in Subei *** used a simple model on equilibrium of adsorption-desorption to present the buffering capacity of *** total P(TP)in the surface sediments ranged from 12.2 to 28.4μmol g^(-1)(average 15.5μmol g^(-1))and was dominated by inorganic ***,exchangeable P,reactive and reductive Fe/Al bound P,and authigenic apatite P significantly decreased northward and eastward from Subei shoal,contrary to the detrital P and organic P *** and particulate inorganic P in the water samples ranged from 0.01 to 0.54μmol L^(-1)(average 0.19μmol L^(-1))and 0.9 to 19.6μmol g^(-1)(average 4.9μmol g^(-1)),*** applied model showed that suspended particulate matter is an important regulator of DIP ***,modification of SPM can alter the DIP buffering *** calculated buffering capacity in the surface layer of the sea water was>60 within Subei shoal and always>10 along the path of floating Ulva prolifera,providing a reasonable explanation for the steady concentration of DIP and its replenishment during the blooming of this green macroalgae.

关键词： phosphorus speciation sediment buffering capacity South Yellow Sea

Predicting Ecological Distribution of the Toxic Dinoflagellate Alexandrium minutum in China Sea Using Ecological Niche Modeling

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2023年第4期22卷 1119-1128页

作者： wang changyou ZHENG Ping GU Haifeng LUO Zhaohe LUO Zhuhua MAO Longjiang ZHANG Yuanzhi School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China Key Laboratory of Marine Biogenetic Resources Third Institute of OceanographyMinistry of Natural ResourcesXiamen 361005China

Alexandrium minutum from the China Sea produces a range of toxins and causes damage to the local ecosystems and *** is essential to understand environmental factors affecting potential *** distributions of *** in the China Sea were predicted based on maximum entropy modeling,and dominant environmental variables were studied through analyses of variable contributions and response *** results showed that highly suitable areas were mainly located in the southwest of the Yellow Sea,the Laizhou Bay,and north of Haizhou *** coast of the South China Sea was predicted as a low-suitability area,and the coast of the East China Sea as an unsuitable *** temperature of the coldest month(T_min)had the largest drop in permutation importance but a low percent *** probability of presence of *** increased with increasing concentration of nitrate(NO3−)and annual mean temperature(T_ann)over a wide range of *** response curves decreased with increasing concentration of phosphate(PO43−)and ratio of NO_(3)^(−)to PO_(4)^(3−)(N_P_ratio)when PO_(4)^(3)−is above 0.049μmolL^(-1) and N_P_ratio above 4,indicating that low values of PO_(4)^(3−) concentration and N_P_ratio favour the occurrence of *** a predictor,the variance of annual temperature(T_Var)had the highest percent contribution and ***_(4)^(3−) was predicted to have much more information than the other variables,and exhibited the second largest drop in permutation importance and percent *** T_Var and PO_(4)^(3−) are the most important dominant predictor variables.

关键词： Alexandrium minutum MaxEnt,habitat suitability environmental variable potential distributions

直肠癌低位前切除术中保留左结肠动脉对低位前切除综合征发生率的影响

在线全文

学校读者我要写书评

暂无评论

中华普通外科杂志 2025年第2期40卷 88-93页

作者：张峻岭丰硕吴涛王长友陈国卫姜勇孙烈刘涛王金贵窦伟冬武颖超汪欣北京大学第一医院胃肠外科北京　100034 华北理工大学胃肠肿瘤外科，唐山　063210

目的探讨低位直肠癌患者术中保留左结肠动脉（LCA）对术后短期肛门功能和生活质量的影响。方法前瞻性纳入2022年1月至2023年12月期间北京大学第一医院胃肠外科的292例直肠癌患者，根据手术中是否保留LCA将患者分为两组，采用LARS量表和E... 详细信息

目的探讨低位直肠癌患者术中保留左结肠动脉（LCA）对术后短期肛门功能和生活质量的影响。方法前瞻性纳入2022年1月至2023年12月期间北京大学第一医院胃肠外科的292例直肠癌患者，根据手术中是否保留LCA将患者分为两组，采用LARS量表和EORTC QLQ-CR29生活质量问卷评估术后肛门功能和生活质量。结果两组在手术出血量、根部淋巴结清扫数量、术后排气时间方面差异均无统计学意义（均P>0.05）。保留LCA组在术后1个月和3个月的LARS评分低于非保留组，特别是在排气失禁、稀便漏出和排便次数方面差异均有统计学意义（均P0.05）。结论在直肠癌低位前切除术中保留LCA有助于降低术后低位前切除综合征的发生率，泌尿系统症状及性功能损害较轻。

关键词：直肠肿瘤结肠动脉综合征泌尿生殖功能直肠切除术

Projective synchronization of a nonautonomous delayed neural networks with Caputo derivative

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Biomathematics 2024年第7期17卷 241-272页

作者： changyou wang Zongxin Lei Lili Jia Yuanhua Du Qiuyan Zhang Jun Liu College of Applied Mathematics Chengdu University of Information Technology Chengdu 610225P.R.China Dianchi College of Yunnan University Kunming Yunnan 650228P.R.China School of Mathematical Sciences Sichuan Normal University Chengdu 610066P.R.China School of Automation Chengdu University of Information Technology Chengdu 610225P.R.China

In this paper,the projective synchronization problem of nonautonomous neural networks with time delay and Caputo derivative is ***,by introducing time delay and variable coefficient into the known neural network model,the neural network that can more accurately describe the interaction between neurons is ***,based on the improved neural network model,two global synchronization schemes are achieved,***,by constructing two novel Lyapunov functions and utilizing the properties of delay fractional-order differential inequalities,the asymptotic stability of the zero equilibrium point of the error system obtained from the master-slave systems is proved by some new developing analysis methods,respectively,and some criteria for global projective synchronization of delayed nonautonomous neural networks with Caputo derivatives are obtained,respectively,under two new synchronous *** addition,the correctness of the theoretical results obtained in this paper is verified by some numerical simulation.

关键词： Time delay Caputo derivative nonautonomous neural network projective synchronization

ON A MULTI-DELAY LOTKA-VOLTERRA PREDATOR-PREY MODEL WITH FEEDBACK CONTROLS AND PREY DIFFUSION

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2019年第2期39卷 429-448页

作者： changyou wang Nan LI Yuqian ZHOU Xingcheng PU Rui LI College of Applied Mathematics Chengdu University of Information Technology Department of Applied Mathematics Southwestern University of Finance and Economics College of Automation Chongqing University of Posts and Telecommunications

This article is focusing on a class of multi-delay predator-prey model with feedback controls and prey diffusion. By developing some new analysis methods and using the theory of differential inequalities as well as constructing a suitable Lyapunov function, we establish a set of easily verifiable sufficient conditions which guarantee the permanence of the system and the globally attractivity of positive solution for the predator-prey ***, some conditions for the existence, uniqueness and stability of positive periodic solution for the corresponding periodic system are obtained by using the fixed point theory and some new analysis techniques. In additional, some numerical solutions of the equations describing the system are given to verify the obtained criteria are new, general, and easily verifiable. Finally, we still solve numerically the corresponding stochastic predator-prey models with multiplicative noise sources, and obtain some new interesting dynamical behaviors of the system.

关键词： predator-prey model: delay diffusion: permanence attractivity periodic solution

Response of harmful dinoflagellate distribution in the China seas to global climate change

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2024年第12期43卷 102-112页

作者： changyou wang Yuxing Tang Bernd Krock Yiwen Xu Zhuhua Luo Zhaohe Luo School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Alfred Wegener Institut Helmholtz Zentrum für Polar-und MeeresforschungBremerhaven D-27570Germany Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China Key Laboratory of Marine Biogenetic Resources Third Institute of OceanographyMinistry of Natural ResourcesXiamen 361005China

By establishing a distribution and environmental factor database of 21 typical harmful dinoflagellates in global waters,the MaxEnt model was used to predict shifts in the habitat of harmful dinoflagellates in Chinese waters under global climate *** results revealed that offshore distance was the most important predictive factor and that surface seawater temperature(SST),primary productivity,and nitrate concentration were the key ecological factors influencing the distribution of harmful *** the low greenhouse gas emission scenario defined by the Intergovernmental Panel on Climate Change(IPCC),by approximately 2050,17 of the 21harmful dinoflagellate species in high-suitability areas(HSA)will migrate northward,six species will migrate eastward,and six species will expand their *** 2100,approximately 18 of the 21 harmful dinoflagellate species in HSA will have migrated northward,seven species will have migrated eastward,and four species will have expanded their ***,the HSA content of highly toxic Alexandrium minutum is expected to increase by 13.4%and 9.4%by 2050 and 2100,*** the high greenhouse gas emissions,there will be 17species migrating northward,6 species migrating eastward,and 4 species increasing in their size in HSA by 2050;moreover,there will be 16 species migrating northward,2 migrating eastward,and 4 species according to their size of HSA by ***,the HSA of *** is predicted to increase by 7.0%and 25.9%by 2050 and 2100,***,***,which is currently seldom present in the China seas,is predicted to exhibit an HSA in most coastal areas of the Yellow Sea,the Bohai Sea,the Hangzhou Bay,the Zhejiang Coast,and the Beibu Gulf of the South China ***,the HSA of Noctiluca scintillans,a typical red-tide species,will be reduced by 7%–90%.The northward migration of Karenia mikimotoi exceeded 100 km and 300 km under low and high greenhouse gas emission scenarios,respec

关键词： harmful dinoflagellate climate change suitable habitat MaxEnt species distribution shifts