检索结果-南通市图书馆

Differences in major ions as well as hydrogen and oxygen isotopes of sediment pore water and lake water

Water Science and Engineering 2018年第2期11卷 147-156页

作者： Zhuo Zhang hua-ming guo Zhen Wang State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences MOE Key Laboratory of Groundwater Circulation & Environment Evolution China University of Geosciences School of Water Resources and Environment China University of Geosciences

Isotopic and chemical compositions of pore water(PW) are highly relevant to environmental and forensic study. Five lake water(LW)samples and five sediment samples were collected to investigate the effects of pore sizes of sediments on PW chemistry and stable isotopes and determine mechanisms controlling their variations. Six pore water fractions were extracted from different-sized pores in each sediment sample at six sequential centrifugal speeds for chemical and isotopic analysis. The sediments consisted mainly of quartz, feldspar, and clay minerals. The hydrogen and oxygen isotopic compositions of PW are mainly controlled by the overlying LW, although the lag effect of exchange between overlying LW and PW results in isotopic differences when recharge of LW is quicker than isotopic exchange in PW. Identical isotopic compositions of PW from sediments with different pore sizes indicate that isotopic exchange of water molecules with different pore sizes is a quick process. The ratio of average total dissolved solid(TDS) concentration of PW to TDS concentration of LW shows a strong relationship with adsorption capacity of sediments, demonstrating that remobilization of ions bound to sediments mainly causes a chemical shift from LW to *** of Ca^(2+), Mg^(2+),and Cl^-in PW remain unchanged,while concentrations of Na^+,K^+,and SO_4^(2-) slightly increase with decreasing pore size. Chemical differences of PW from sediments with different pore sizes are governed by ion adsorption properties and surface characteristics of different-si zed particles.

关键词： Pore size Centrifugal extraction Hydrogen and oxygen isotopes Major ions Remobilization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Well-defined Hierarchical Hydrogen Bonding Strategy to Polyureas with Simultaneously Improved Strength and Toughness

引用

Chinese Journal of Polymer Science 2019年第12期37卷 1257-1266,I0007页

作者： Ting Li Tian-Ze Zheng Zhao-Xia guo Jun Xu Bao-hua guo Key Laboratory of Advanced Materials (Ministry of Education) Department of Chemical Engineering Tsinghua University

A well-defined quadruple hydrogen bonding strategy involving dimerization of 2-ureido-4[1H]-pyrimidone(UPy)units is innovatively designed to prepare polyureas with high overall mechanical *** polyureas containing different amounts of UPy units were synthesized by replacing a portion of isophorone diisocyanate(IPDI)with a UPy-derived *** formation of quadruple hydrogen bonds in hard segments via UPy dimers was confirmed by nuclear magnetic resonance(NMR)and Fourier transform infrared spectroscopy(FTIR).The mechanical properties of the polyureas were evaluated by uniaxial tensile *** to the polyurea without UPy units,remarkable improvements in Young’s modulus,tensile strength,and toughness were simultaneously achieved when UPy units were *** mechanism behind the strong strengthening effect rooted in the stronger intermolecular forces among hard segments brought by the quadruple hydrogen bonds,which were stronger than the inherent bidentate and monodentate hydrogen bonds among urea groups,and the slower soft segmental dynamics reaveled by both increased Tg and relaxation time of the soft *** mechanism behind the strong toughening effect was ascribed to more effective energy dissipation brought by the quadruple hydrogen bonds that served as stronger sacrificial bonds upon *** work may offer new insight into the design of polyurea elastomers with comprehensively improved mechanical properties.

关键词： Mechanical properties Strength Toughness Quadruple H-bonds Polyurea elasomers

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Single-tube-genotyping of gastric cancer related SNPs by directly using whole blood and paper-dried blood as starting materials

引用

World Journal of Gastroenterology 2006年第24期12卷 3814-3820页

作者： huan huang Ying Bu guo-hua Zhou Medical School Nanjing University Nanjing 210093 China and China Pharmaceutical University Nanjing 210009 China huadong Research Institute for Medicine and Biotechnics Nanjing 210002 China

AIM: To demonstrate an inexpensive method for typing gastric cancer related single nucleotide polymorphisms (SNPs) using whole blood or paper-dried blood as starting materials. METHODS: PCR amplification is directly carried out from the whole blood or paper-dried blood sample without any DNA extraction step. Before PCR, a blood sample, four primers, and all of biological reagents necessary for PCR were added at a time; After PCR, the amplified products were directly separated by slab gel electrophoresis or microchip CE without any purification. SNP typing was performed by tetra-primer PCR with two inner primers specific to each allele and two outer primers defining the length of allele-specific amplicons. Genotypes were directly discriminated by the size of amplicons specific to each allele, thereby avoiding any post-PCR process. RESULTS: Using a special PCR buffer, inhibitory substances in blood (including the anticoagulant in blood) and filter paper were effectively suppressed; a 'true' single-tube-genotyping is thus realized. We successfully determined genotypes IL-1B-511 and IL-1B-31 polymorphisms at the gene IL-1B by using whole-blood and paper-dried blood samples as starting materials respectively. The method is so sensitive that 0.5-1.0μL of blood sample is enough to give a satisfactory typing results. The genotyping results were confirmed by RFLP-PCR using purified genome DNA, indicating that amplification specificity was not affected by inhibitory components (including coagulants) in blood or filter paper. CONCLUSION: Compared with SNP typing methods based on purified DNA, the proposed method is labor saving, simple, inexpensive, and less cross-contaminated. It is promising to use this method to type other SNPs.

关键词： Gastric cancer Whole blood Paper-driedblood Tetra-PCR SNP IL-1B-31 IL-1B-511

来源：

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

辅助生殖技术受孕对双绒毛膜双羊膜囊双胎妊娠早产发生风险的影响研究

引用

中国实用妇科与产科杂志 2024年第2期40卷 235-238页

作者：吴凯佳贾燕张国华王亚男张晶石家庄市第四医院河北石家庄050011

目的探讨辅助生殖技术(assisted reproductive technology,ART)受孕对双绒毛膜双羊膜囊双胎妊娠早产发生风险的影响。方法回顾性分析2018年1月至2022年12月于石家庄市第四医院产检并分娩至少一胎活产的双绒毛膜双羊膜囊双胎妊娠2501例... 详细信息

目的探讨辅助生殖技术(assisted reproductive technology,ART)受孕对双绒毛膜双羊膜囊双胎妊娠早产发生风险的影响。方法回顾性分析2018年1月至2022年12月于石家庄市第四医院产检并分娩至少一胎活产的双绒毛膜双羊膜囊双胎妊娠2501例。依据受孕方式,分为自然受孕组(n=1223)和ART组(n=1278),比较两组早产发生率及早产儿不良结局事件发生比例。结果ART组早产发生率显著高于自然受孕组(52.35%vs.48.24%,P0.05)。结论与自然受孕相比,ART受孕方式可显著增加双绒毛膜双羊膜囊双胎妊娠早产发生率,尤其增加孕32周前早期早产的发生以及自发性早产的发生,同时ART早产儿出生体重更低,入住NICU率高、住院时长偏长。因此,对ART受孕的双绒毛膜双羊膜囊双胎孕妇应加强孕期保健及管理,积极预防早期早产的发生。

关键词：双胎妊娠早产辅助生殖技术双绒毛膜双羊膜囊双胎

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

江苏省特色学徒制的发展现状与推进策略

引用

江苏经贸职业技术学院学报 2024年第3期 59-62页

作者：申燕萍周国华常州工业职业技术学院信息工程学院江苏常州213164

现代学徒制和企业新型学徒制共同组成中国特色学徒制。江苏省作为职业教育的改革先锋,两种学徒制试点工作均走在全国前列。目前,现代学徒制已成为校企合作的重要途径,为企业输送了大量“定制”人才;企业新型学徒制为构建现代化产业体系... 详细信息

现代学徒制和企业新型学徒制共同组成中国特色学徒制。江苏省作为职业教育的改革先锋,两种学徒制试点工作均走在全国前列。目前,现代学徒制已成为校企合作的重要途径,为企业输送了大量“定制”人才;企业新型学徒制为构建现代化产业体系提供了有力支撑。江苏省存在两种学徒制财政支持政策不一、小微企业参与有难度、教学监控评价体系不健全、双导师制度未能有效落实等问题。需要统一两种学徒制的财政补贴政策;强化制度建设,加大扶持力度;建立质量标准,加大监管力度;校企协同建设一体化师资队伍。

关键词：江苏省企业现代学徒制企业新型学徒制职业院校

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Global Classical Solution for a Three-dimensional Viscous Liquid-gas Two-fluid Flow Model with Vacuum

引用

Acta Mathematicae Applicatae Sinica 2014年第4期30卷 989-1006页

作者： Lei YAO Jing YANG Zhen-hua guo School of Mathematics and Center for Nonlinear Studies Northwest University

This is a continuation of the paper （J. Math. Phys., 52（2011）, 093102）. We consider the Cauchy problem to the three-dimensional viscous liquid-gas two-fluid flow model. The global existence of classical solution i... 详细信息

关键词： Viscous liquid-gas two-fluid flow model classical solution vacuum

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

马铃薯茎叶还田对土壤理化性质及细菌群落结构的影响

引用

西南农业学报 2024年第1期37卷 145-153页

作者：周远平罗文娇周平王琼郭华春云南农业大学农学与生物技术学院昆明650201 云南农业大学机电工程学院昆明650201

【目的】探究马铃薯茎叶还田对土壤理化性质和细菌群落结构的影响。【方法】基于土壤理化分析和Illumina高通量测序技术,对比分析马铃薯茎叶还田(处理组R)与不还田(处理组NR)土壤理化指标和细菌群落结构的差异。【结果】与处理CK相比,... 详细信息

【目的】探究马铃薯茎叶还田对土壤理化性质和细菌群落结构的影响。【方法】基于土壤理化分析和Illumina高通量测序技术,对比分析马铃薯茎叶还田(处理组R)与不还田(处理组NR)土壤理化指标和细菌群落结构的差异。【结果】与处理CK相比,马铃薯茎叶还田提高土壤pH及有机质、碱解氮、有效磷、速效钾含量,其中速效钾含量增幅最大,达42.36~141.53 mg/kg。马铃薯茎叶还田显著影响土壤细菌群落结构,在第45、90天时,还田处理土壤中12个细菌类群丰度显著提高,且还田处理较不还田处理土壤细菌群落的物种多样性显著提高。各处理土壤细菌群落的种间互作关系主要发生在酸杆菌门、放线菌门(Actinobacteriota)和变形菌门,且马铃薯茎叶还田处理较不还田处理,土壤细菌群落种间互作强度显著提高。相关性分析表明,Latescibacterota、脱硫菌门(Desulfobacterota)与有效磷含量呈极显著负相关,与碱解氮、有机质含量呈显著正相关;粘球菌门(Myxococcota)、Bdellovibrion⁃ota、髌骨菌门(Patescibacteria)、肠杆菌门(Entotheonellaeota)、芽单胞菌门(Gemmatimonadota)、硝化螺旋菌门(Nitrospirota)、变形菌门(Proteobacteria)与速效钾含量呈显著正相关。【结论】马铃薯茎叶还田处理可以提高土壤养分含量,显著提高土壤细菌群落的物种多样性及群落物种互作强度,土壤速效钾、有效磷、碱解氮及有机质含量等理化指标与土壤细菌群落物种组成存在显著的相关关系。

关键词：马铃薯茎叶还田土壤理化性质细菌群落

来源：

维普期刊数据库

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Facile Preparation of Electromagnetic Interference Shielding Materials Enabled by Constructing Interconnected Network of Multi-walled Carbon Nanotubes in a Miscible Polymeric Blend

引用

Chinese Journal of Polymer Science 2020年第6期38卷 593-598页

作者： Qi-Yan Zhang Han-Song Li Bao-hua guo Zhao-Xia guo Jian Yu Key Laboratory of Advanced Materials(Ministry of Education) Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

Electromagnetic interference(EMI)shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation *** with their metal counterparts,conductive polymer composites(CPCs)have unique advantages of lightweight,corrosive resistance,low cost,and excellent processability,and are therefore an ideal choice for developing high-performance EMI shielding ***,CPCs based EMI shielding materials are limited to high filler loading,which caused poor mechanical properties and ***,we demonstrate a facile and highly scalable approach to develop high-performance EMI shielding materials with low filler loading by using miscible poly(phenylene oxide)/polystyrene(PPO/PS)blend as the *** contrast to PS/carbon nanotubes(CNTs)composites,PPO/PS/CNTs composites show much higher EMI shielding effectiveness caused by good dispersion of CNTs and highly interconnected conductive *** excellent EMI shieling effectiveness of 23-25 dB is achieved for PPO/PS/10%CNTs composites with a thickness of only 375 pm;which is superior to most of reported polymer/CNTs composites prepared by *** addition,the results show that although absorption is the major shielding mechanism,the contribution of reflection is also important and closely related to the connectivity of conductive network,as well as the electrical conductivity of the CPCs.

关键词： Conductive polymer composites Polymer blend Electromagnetic interference shielding Conductive network Dispersion

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

贵州省一起产气荚膜梭菌引起食源性疾病暴发事件的调查及病原体溯源

引用

中国食品卫生杂志 2024年第5期36卷 557-563页

作者：张莉代华简洁黄靖宇蒋家俊周亚娟田继贵朱姝廖春李军李薇薇郭华贵州医科大学公共卫生与健康学院劳动卫生与环境卫生学系贵州贵阳550025 贵州省疾病预防控制中心贵州贵阳550004 国家食品安全风险评估中心北京100022 贵阳市疾病预防控制中心贵州贵阳550000

目的对贵阳市某学校由产气荚膜梭菌引起发的食源性疾病暴发事件开展流行病学调查和病因食品和病原的溯源分析,探讨全基因组测序新技术在食源性疾病暴发溯源中的应用。方法采用现场流行病学分析,采集可疑生物样本,食品样本和外环境样本... 详细信息

目的对贵阳市某学校由产气荚膜梭菌引起发的食源性疾病暴发事件开展流行病学调查和病因食品和病原的溯源分析,探讨全基因组测序新技术在食源性疾病暴发溯源中的应用。方法采用现场流行病学分析,采集可疑生物样本,食品样本和外环境样本进行常规的实验室病原分离及沙门菌、致泻大肠埃希菌、金黄色葡萄球菌、蜡样芽胞杆菌和产气荚膜梭菌的病原鉴定。对分离的病原菌进行毒素基因检测和全基因组测序溯源分析。结果22名病例症状以腹痛(95.45%,21/22)、腹泻(95.45%,21/22)为主;流行曲线为点源暴露模式,潜伏期为6-15 h。在5份肛拭子样本、3份粪便样本和1份留样早餐肉末食品样本中分离出产气荚膜梭菌,且均检出肠毒素cpe基因,所有样本均未检出沙门菌、致泻大肠埃希菌、金黄色葡萄球菌和蜡样芽胞杆菌。其中早餐肉末食品样品中经全基因组测序分析对比发现产气荚膜梭菌为3.5×10^(5) CFU/g,经全基因组测序分析比对发现,来源于早餐肉末食品和肛拭子样本的产气荚膜梭菌,其分子分型为ST139型,菌株均携带cpe毒力基因。结论通过现场调查和溯源分析,判定产气荚膜梭菌污染早餐肉末是导致此次食源性疾病暴发的原因。全基因组测序新技术在食源性疾病暴发中可起到精准溯源作用。

关键词：产气荚膜梭菌食源性疾病暴发事件毒素基因溯源分析食源性致病菌

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A remote sensing system of vehicle emissions based on tunable diode laser technology

引用

Journal of Environmental Sciences 2006年第1期18卷 154-157页

作者： ZENG Jun guo hua-fang HU Yue-ming College of Automation Science and Engineering South China University of Technology Guangzhou 510640 China

As being an effective real-time method of monitoring vehicle emissions on-road, a remote sensing system based on the tunable diode laser （TDL） technology was presented, and the key technologies were discussed. A field test in Guangzhou（Guangdong, China） was performed and was found that the factors, such as slope, instantaneous speed and acceleration, had significant influence on the detectable rate of the system. Based on the results, the proposal choice of testing site was presented.

关键词： remote sensing tunable diode laser vehicle emission detectable rate

来源：

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：