九龙江流域河流磷输出对土地利用模式及水文状况的响应

本研究应用现场监测、地理信息技术(GIS)、模型模拟和数理统计等方法,基于2015年3月至2017年2月九龙江流域不同主导土地利用类型源头小流域和两条干流河流表层水总磷(TP)、总溶解态磷(TDP)和颗粒态磷(PP)的浓度监测,探究河流磷浓度与输出负荷的时空变化特征,揭示九龙江流域磷输出对土地利用模式及水文状况的响应.结果发现,九龙江流域河流磷浓度和磷输出负荷具有明显的时空变异性.在空间上,农业流域>城市流域>自然流域,西溪>北溪.在季节上,不同类型流域不同形态磷浓度总体表现为春、冬季节较高,而夏、秋季节较低.TP、TDP、和PP输出负荷春、夏季高于秋、冬季,与径流深度的变化趋势基本一致.磷浓度、输出负荷与林地和裸地面积百分比呈负相关关系,与耕地、果园面积百分比呈正相关关系.但不同季节,磷浓度和输出负荷对土地利用和水文状况的响应存在差异,在夏季的相关性最强.结果表明农业非点源污染是九龙江流域河流磷的关键源,提升林地比例有助于保持水土,改善河流水质,尤其在雨季.国家自然科学基金项目(41471154)厦门大学校长基金项目(20720150129

B_2×B_2的全纯自同构群

讨论B2×B2上的全纯自同构群,并计算它的B ergm an核函数及其自同构的Jacob i行列式

Preliminary Analysis of Spatiotemporal Variation of Water Quality and Its Influencing Factors in the Jiulong River Watershed

选取闽东南九龙江流域21个典型小流域开展2010年丰(8月)、平(11月)、枯(2月)3个水期的基流水质监测,并借助gIS、多元统计分析方法识别流域水质的时空分布特征及其影响因素,为九龙江流域水质监测、管理与控制提供依据.结果表明,九龙江水质枯水期最差,平水期次之,丰水期水质较好.表征生活污水、工业废水的污染因子对水质变化的贡献率为45.58%,表征农业污染的主成分的贡献率为21.28%.nH4+-n、SrP、高锰酸盐指数、k+、Cl-、Mg2+、nA+浓度与建设用地比例、人口密度呈显著的正相关,nO3--n浓度与耕地比例有显著的正相关,自然用地面积比例与nO3--n、k+、Cl-、nA+浓度有显著的负相关.建设用地比例较大、人口较密集的小流域nH4+-n、SrP、高锰酸盐指数、k+、Cl-的浓度较高,耕地比例较大的小流域nO3--n浓度则较高.在流域水质管理上,建议提高污水处理率,并重视由于化肥施用导致的农业非点源污染对水质的影响.Twenty one sub-watersheds in the Jiulong River watershed were chosen for in-situ monitoring water quality of baseflow in flood season,dry season and average season in 2010.Geographical information system and multivariate analysis were coupled to characterize the spatiotemporal variation of water quality and identify its influencing factors.The results show that the water quality in dry season is the worst whereas the water quality in flood season is comparatively good.The first principal component representing sanitary and industrial wastewater pollution,explained 45.58% of the total variance of water quality.The second principal component concerning pollution due to agricultural activities,explained 21.28% of the total variance.NH+4-N,SRP,potassium permanganate index,K+,Cl-,Mg2+ and Na+had a significantly positive correlation with percentage of built-up and density of population.NO-3-N was correlated positively with percentage of cropland.The sub-watersheds with high proportion of build-up area and density of population show high concentration of NH+4-N,SRP,potassium permanganate index,K+,Cl-.Comparatively,the sub-watersheds with high percentage of cropland show high level of nitrate concentration.Improvement of the wastewater treatment efficiency and increased recognition of agricultural non-point source pollution were finally highlighted from watershed management perspectives.国家自然科学基金项目(40901100;40810069004);福建省自然科学基金项目(2009J01222

基于增量式自学习策略的多语言翻译模型

针对源语言到目标语言缺乏平行语料的情况,提出了一种基于增量式自学习策略的多语言翻译模型,即利用中介语双语语料训练源语言到目标语言的翻译模型.在Transformer架构下,相比于基于中介语和直接在伪平行语料上训练的普通双语翻译模型,使用该方法在第十四届全国机器翻译研讨会(CWMT 2018)多语言翻译评测数据集上的机器双语互译评估(BLEU)值提升了0.98个百分点.在此基础上,还对比了不同的预处理方法、训练策略以及多模型的平均和集成策略,其中多模型集成策略的BLEU值上可在多模型策略的基础上进一步提升0.53个百分点.国家科技支撑计划项目(2012BAH14F03);;国家自然科学基金(61573294);;教育部博士点基金(20130121110040);;国家语委委托项目(WT135-10);国家语委甲骨文专项(YWZ-J010

Study on the variation of the iodine nutrition status among children aged 8 to 10 and pregnant women in Xiamen city after the implement of new standard of iodized salt supply

目的研究新标碘盐供应前后厦门市沿海8-10岁儿童和孕妇的碘营养变化情况,为下一步碘缺乏病防控策略调整提供实证依据。方法在新标碘盐供应前及食用新标碘盐后的第3、6、9个月调查厦门市翔安区8-10岁学生和孕妇的尿碘、尿比重、碘盐覆盖率、碘盐合格率、合格碘盐食用率和居民日人均食盐摄入量。结果自来水水碘含量为4.2μg/l,基线调查、第二、三次评估日人均食盐摄入量均数分别为5.7、6.9、6.9 g;基线调查、第一、第二、三次评估,8-10岁学生碘盐合格率和合格碘盐食用率都分别为97.1、93.1、98.0和98.0,盐碘中位数分别为28.7、24.7、24.0、25.3 Mg/kg,尿碘中位数分别为132.0、177.7、181.7和134.5μg/l,尿比重均值分别为1.0157、1.0196、1.0213和1.0184;孕妇碘盐合格率分别为97.8%、84.6%、84.4%和90.2%,盐碘中位数分别为27.8、25.7、24.3和23.7Mg/kg,尿碘中位数分别为103.8、128.5、138.9和100.2μg/l,尿比重均值分别为1.0123、1.0153、1.0180和1.0143;尿碘与采样季节、气候及尿比重有关,尿碘值与尿比重呈正相关关系。结论新标碘盐实施前后,8-10岁儿童碘营养总体处于适宜水平,但孕妇碘营养均不足,要采取措施加强孕妇碘营养,保障人群健康素质。Objective To investigate the variation of iodine nutrition among children aged 8 to 10 and pregnant women after the implement of new standard of iodized salt supply, and to provide evidence for the further adjustment of control strategy against iodine deficiency disease.Method Survey has been performed to acquire the urinary iodine, specific gravity, iodized salt coverage rate, iodized salt qualification rate, qualified iodized salt consumption rate and average daily salt intake among children aged 8 to10 and pregnant women in Xiamen city.It has been conducted for 3 times repeatedly with a regular interval of 3 months after the implement of new standard.Results The tap water iodine content was 4.2 μg / L.The average daily salt intake of baseline survey, second and third assessment was 5.7, 6.9 and 6.9 g respectively.The iodized salt coverage rates among children aged 8 to10 and pregnant women were all reached 100% in 4 assessments.Among children aged 8 to 10, iodized salt qualification rate and qualified iodized salt consumption rate for 4 assessments were 97.1, 93.1, 98.0 and 98.0 respectively.Median of iodine salt samples was 28.7, 24.7, 24.0 and 25.3 mg / kg, respectively.The median of urinary iodine was 132.0,1 77.7, 181.7 and134.5 μg / L,respectively.The mean of specific gravity was 1.0184, 1.0157, 1.0196 and 1.0213, respectively.Among the pregnant women, the iodized salt qualification rate and qualified iodized salt consumption rate of pregnant women were 97.8, 84.6, 84.4 and 90.2%, respectively.Median of iodine salt samples was 27.8, 25.7, 24.3 and 23.7 mg / kg, respectively.Median of urinary iodine was 103.8, 128.5, 138.9 and 100.2 μg / L,respectively.Mean of specific gravity was 1.0123,1.0153,1.0180 and 1.0143, respectively.Urinary iodine was correlated with season of sampling, climate and specific gravity, and urinary iodine was positively correlated with specific gravity.Conclusion The iodine nutrition status of children aged 8 to 10 was remained in adequate level regardless of the implement of new standard of iodized salt.However, the results suggested that the corresponding indicator among pregnant women was in a relatively low level.Proper countermeasure should be taken to enhance the iodine su-pply among them and to further secure the quality of general population

Single-crystal-like hematite colloidal nanocrystal clusters: synthesis and applications in gas sensors, photocatalysis and water treatment

A facile and efficient one-pot solvothermal synthetic route based on a simplified self-assembly is proposed to fabricate spherical hematite colloidal nanocrystal clusters (CNCs) of uniform shape and size. The as-prepared hematite CNCs are composed of numerous nanocrystals of approximately 20 nm in size, and present a single-crystal-like characteristic. A possible formation process based on the nucleation-oriented aggregation-recrystallization mechanism is proposed. Our experiments demonstrated that both the surfactant and the mixed solvent play very critical roles in controlling the size of primary nanocrystals and the final morphology of single-crystal-like spherical CNCs. Compared with other hematite nanostructures, the spherical hematite CNCs show outstanding performance in gas sensing, photocatalysis and water treatment due to their large surface area and porous structure. In addition, interesting tertiary CNCs formed by further assembly of secondary spherical CNCs were observed for the first time.NNSFC,20525103,20531050,20721001,20725310,20801045,2007CB81530

The Modulation of Teletext Decoder and the Analysis of the CoeFFicient of Error Code

本文联系XT—5131P/S（T）图文电视接收机解码器的研制实践分析误码的原因和讨论降低误码率的方法。In the light of the practice in developing the decoder of XT 5131 P/S(T)teletext receiver,an analysis is made of the causes of error codes ,and measures to reducethe coeFFicient of error codes are suggested

微波等离子体化学法合成TiN纳米粉体材料研究

利用TiCl_4(蒸汽)+N_2+H_2气相反应体系,采用微波等离子体加强气相化学反应法制备出了TiN纳米粉体材料。利用XRD、TEM、BET以及激光粒度分析等研究分析了粉体的物相、形貌、比表面积、粒径等性质。结果表明用微波等离子体化学法,在微波输出功率为4KW,常压条件下可获得外观为黑色的TiN纳米粉体材料,其平均粒径在20-40nm之间,比表面积在30-60m~2/g之间

Holomorphic automorphism group of B2×B 2

摘　要　讨论B2×B2 上的全纯自同构群, 并计算它的Bergman 核函数及其自同构的Jacobi 行 列式. Abstract　In th is paper w e first investigate the holomorph ic automorph ism group of B 2×B 2, then calculate the Bergman kernel and the Jacobi determ inant of the automorph ism of B 2×B 2.国家自然科学基金(10501036; 10271097) ; 福建省自然科学基金资助项目(J 0511003