检索结果-南通市图书馆

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

宁夏天然草地土壤有机碳分布格局及驱动因素

草原与草坪 2024年第4期44卷 1-8页

作者：李旭梅杨钧李小伟周亮黄文广杨君珑宁夏大学农学院宁夏银川750021 宁夏草原工作站宁夏银川750021

【目的】草地作为重要的土壤碳库,探究其有机碳的分布格局及影响因素对缓解温室效应、草地生态系统评价以及退化草地生态恢复具有重要意义。【方法】以宁夏3种类型天然草地(草甸草原、典型草原、荒漠草原)为研究对象,在195个样地测定0~2... 详细信息

【目的】草地作为重要的土壤碳库,探究其有机碳的分布格局及影响因素对缓解温室效应、草地生态系统评价以及退化草地生态恢复具有重要意义。【方法】以宁夏3种类型天然草地(草甸草原、典型草原、荒漠草原)为研究对象,在195个样地测定0~20 cm和20~40 cm土层土壤有机碳(Soil Organic Carbon,SOC)含量,利用分段结构方程模型(Segmented structural equation model)揭示土壤SOC含量与地理、气候、植被、和土壤因子的关系。【结果】在水平方向上0~20 cm和20~40 cm土层SOC平均含量分别为9.46和8.25 g/kg,草甸草原>典型草原>荒漠草原;在垂直剖面上SOC平均含量随土层深度增加而减少;由南到北呈递减的变化趋势。分段结构方程表明:在0~20和20~40 cm土层中SOC含量与TN、TP和丰富度指数呈极显著正相关(P土壤因子(0.21)>丰富度指数(0.12)。20-40 cm土层中,总效应由大到小依次为土壤因子(0.39)>气候因子(0.23)>丰富度指数(0.13)。【结论】分段结构方程结果显示雨热条件是影响表层土壤SOC含量的主要因子,TN和TP是影响深层土壤SOC含量的主要因子。

关键词：宁夏天然草地有机碳环境因子结构方程模型

Concentrated Fluoride-medium Route to Synthesis of One-dimensional Fluoroaluminophosphate Chain (C_4H_(15)N_3)[AlPO_4F_2]

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2010年第5期26卷 699-701页

作者： liU Yang HAN Yi-de li Yi SONG xiao-wei li Ji-yang YU Ji-hong XU Ru-ren State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 P. R. China

A new one-dimensional（ID） fluoroaluminophosphate chain（C4H15N3）[AlPO4F2]（denoted AIPO-CJ28） was synthesized in the concentrated fluoride synthetic medium with a gel composition of 1.0Al（OPr^1）a：1.0H3PO4： 5.4DETA：1.3HF：2.0H2O（DETA=diethylenetriamine）. The reagents were mixed directly without introducing additional water solvent. The 1D chain is constructed by alternating AlO2F2 arid doubly bridging PO4 tetrahedra to form the simplest serrate chain. AIPO-CJ28 can be transformed to another 1D aluminophosphate chain A1PO-CSC upon further crystallization at 230 ℃.

关键词： Fluoroaluminophosphate Concentrated fluoride-medium Phase transformation Chain structure

Effect of Aluminium Nanoparticles on the Performance of Bulk Heterojunction Organic Solar Cells

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2012年第9期29卷 211-214页

作者： YANG Shao-Peng YAO Ming JIANG Tao li Na ZHANG Ye li Guang li xiao-wei FU Guang-Sheng College of Physics Science and Technology Hebei UniversityBaoding 071002

Al nanoparticles(NPs)are incorporated in the active layers to enhance the performance of organic solar cells(OSCs).The improved short circuit current Jsc and power conversion efficiency(PCE)for OSCs with Al NPs are observed.A final PCE of 3.66wt%is achieved,which is an improvement of more than 30wt%compared to a standard cell with a PCE of 2.84wt%.When the mass of Al NPs is 10wt%of OSCs,the device performance is *** optical performance of OSCs reveals that the absorption from sunlight *** external quantum efficiency spectra suggests that the Al NPs in the active layers influence the efficiency of converting photons into electrons,which leads to the improvements in the *** enhanced photovoltaic performance induced by incorporating Al NPs in the active layer is discussed in the terms of increasing charge separation at the donor-acceptor interface and the effectively decreasing transmission distance of charge in polymer.

关键词： Solar performance nanoparticles

高分辨T2联合弥散加权成像在直肠癌术前TNM分期评估中的应用价值

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国肛肠病杂志 2024年第6期44卷 5-7页

作者：李晓维张伯英程秋波轩翠华联勤保障部队第九八九医院磁共振室河南洛阳471000

目的:探讨高分辨磁共振(MR)T2加权成像(T2WI)联合弥散加权成像(DWI)在直肠癌患者术前TNM分期中的应用价值。方法:选取2021年1月至2023年1月,本院收治的102例直肠癌患者,术前均行T2WI和DWI序列扫描,以病理诊断结果为金标准,采用Kappa一... 详细信息

目的:探讨高分辨磁共振(MR)T2加权成像(T2WI)联合弥散加权成像(DWI)在直肠癌患者术前TNM分期中的应用价值。方法:选取2021年1月至2023年1月,本院收治的102例直肠癌患者,术前均行T2WI和DWI序列扫描,以病理诊断结果为金标准,采用Kappa一致性检验法评估T2WI联合DWI行TNM分期的一致性。结果:T2WI联合DWI诊断直肠癌T分期的总准确率为90.20%(92/102),与病理T分期的一致性极好(Kappa值=0.864,P<0.05),其中T1、T2、T3和T4期的灵敏度、特异度及准确度分别为100.00%、98.84%、99.02%;82.35%、95.29%、93.14%;92.00%、93.06%、92.62%;84.21%、100.00%、97.06%。T2WI联合DWI诊断直肠癌N分期的总准确率为79.41%(81/102),与病理N分期的一致性良好(Kappa值=0.705,P<0.05),其中N0、N1、N2期的灵敏度、特异度和准确度分别为87.30%、87.18%、87.25%;56.52%、86.08%、79.41%;81.25%、94.19%、92.16%。结论:T2WI联合DWI诊断直肠癌TNM分期的准确度较高,有助于为临床诊断提供参考依据。

关键词：直肠癌 T2加权成像弥散加权成像 TNM分期

Primary mixed germ cell tumor of the liver with sarcomatous components

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2010年第5期16卷 652-656页

作者： Xu, Ai-Min Gong, Shao-Juan Song, wei-Hua li, xiao-wei Pan, Chun-Hua Zhu, Jun-Jun Wu, Meng-Chao Second Mil Med Univ Dept Intervent Radiotherapy 3 Eastern Hepatobiliary Surg Hosp Shanghai 200438 Peoples R China

Germ cell tumor(GCT)of the liver is extremely rare. Here,we describe a case of hepatic mixed GCT with significant sarcomatous components and elevated serum α-fetoprotein(AFP)in a 34-year-old ***,the tumor was composed of two GCTs components:yolk sac tumor and immature *** predominant components of immature teratoma consisted of several types of tissue that represented different germinal layers(endoderm,mesoderm and ectoderm) and showed varying degrees of differentiation with significant sarcomatous *** yolk sac component showed positivity for AFP and cytokeratin(AE1/ AE3).The immature teratoma components showed positivity for varying differentiation *** cytogenetic analysis revealed that the yolk sac tumor and immature teratoma were positive for i(12p)and 12p *** particular,the rhabdomyoblastic components also showed typical i(12p)and 12p *** suggested that sarcomatous components may be associated with dedifferentiation or malignant transformation of certain mesenchymal components within teratoma.

关键词： Germ cell tumor Teratoma Sarcoma liver neoplasms

Influence of topography on the fine structures of stratospheric gravity waves:An analysis using COSMIC-2 temperature data

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2024年第3期8卷 497-513页

作者： JiaRui wei xiao liu JiYao Xu QinZeng li Hong Gao State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Institute of Electromagnetic Wave School of PhysicsHenan Normal UniversityXinxiang Henan 453000China

We derive the potential energy of gravity waves(GWs)in the upper troposphere and stratosphere at 45°S-45°N from December 2019 to November 2022 by using temperature profiles retrieved from the Constellation Observing System for Meteorology,Ionosphere,and Climate-2(COSMIC-2)*** to the dense sampling of COSMIC-2,in addition to the strong peaks of gravity wave potential energy(GWPE)above the Andes and Tibetan Plateau,we found weak peaks above the Rocky,Atlas,Caucasus,and Tianshan *** land-sea contrast is responsible for the longitudinal variations of the GWPE in the lower and upper *** 40°N/S,the peaks were mainly above the topographic regions during the *** 20°N/S,the peaks were a slight distance away from the topographic regions and might be the combined effect of nontopographic GWs and mountain *** the Equator,the peaks were mainly above the regions with the lowest sea level altitude and may have resulted from *** results indicate that even above the local regions with lower sea level altitudes compared with the Andes and Tibetan Plateau,the GWPE also exhibits fine structures in geographic *** found that dissipation layers above the tropopause jet provide the body force to generate secondary waves in the upper stratosphere,especially during the winter months of each hemisphere and at latitudes of greater than 20°N/S.

关键词： topography fine structures stratospheric gravity waves Constellation Observing System for Meteorology Ionosphere and Climate-2(COSMIC-2) dissipation layers

Coupling effect of cement-stabilization and biopolymer-modification on the mechanical behavior of dredged sediment

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3284-3298页

作者： Lei Lang Jiangshan li xiao Huang Ping Wang wei Zhang State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Hubei Provincial Key Laboratory of Contaminated Sludge and Soil Science and Engineering Wuhan430071China University of Chinese Academy of Sciences Beijing100049China

Nowadays,biopolymer stabilization as a promising eco-friendly approach in soft ground improvement has attracted wide ***,the feasibility of using biopolymer as a green additive of cementstabilized dredged sediment(CDS)with high water content is still *** this study,guar gum(GG)and xanthan gum(XG)were adopted as typical biopolymers,and a series of unconfined compressive strength(UCS),splitting tensile strength(STS)and scanning electron microscopy(SEM)tests were performed to evaluate the mechanical and microstructural properties of XG-and GG-modified CDSs considering several factors including biopolymer modification,binderesoil ratio and wateresolid ***,the micro-mechanisms revealing the evolutions of mechanical properties of biopolymermodified CDS were *** results indicate that the addition of XG can effectively improve the strength of CDS,while the GG has a side *** XG content of 9%was recommended,which can improve the 7 d-and 28 d-UCSs by 196%and 51.8%,together with the 7 d-and 28 d-STSs by 118.3%and 42.2%,*** the binderesoil ratio or decreasing the wateresolid ratio significantly improved the strength gaining but aggravated the brittleness characteristics of *** XG to CDS contributed to the formation of microstructure with more compactness and higher cementation degrees of ordinary Portland cement(OPC)-XG-stabilized DS(CXDS).The micro-mechanism models revealing the interactions of multiple media including OPC cementation,biopolymer film bonding and bridging effects inside CXDS were *** key findings confirm the feasibility of XG modification as a green and high-efficiency mean for improving the mechanical properties of CDS.

关键词： Dredged sediment(DS) Stabilization Biopolymer modification Mechanical properties Micro-mechanism

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

外墙干挂石材内粘贴岩棉保温施工方法研究

建筑技术开发 2024年第10期51卷 100-102页

作者：王春艳张家浩李晓伟王哲中建二局第三建筑工程有限公司北京100070 中建三局集团有限公司武汉430064

随着绿色节能环保意识的加强,人们对建筑物的美观程度、施工质量及耐久性都提出了更高的要求。传统的涂料施工存在质感较差、寿命周期短、漏水等缺陷。然而保温砌块大多无法满足节能要求,而外贴保温板,日久经风雨等恶劣气候侵蚀易脱落... 详细信息

随着绿色节能环保意识的加强,人们对建筑物的美观程度、施工质量及耐久性都提出了更高的要求。传统的涂料施工存在质感较差、寿命周期短、漏水等缺陷。然而保温砌块大多无法满足节能要求,而外贴保温板,日久经风雨等恶劣气候侵蚀易脱落。干挂石材、粘贴保温板施工方法可以较好地解决上述问题。该种外墙保温系统大多由专业分包队伍进行施工,且多使用吊篮作业。本研究主要介绍如何合理安排二者工序的穿插,降低施工成本,保证工程质量。

关键词：干挂石材岩棉板埋板

Generalized Ridge and Principal Correlation Estimator of the Regression Parameters and Its Optimality

在线全文

学校读者我要写书评

暂无评论

Journal of Mathematical Research and Exposition 2009年第5期29卷 882-888页

作者： GUO Wen Xing ZHANG Shang li XUE xiao wei School of Science Beijing Jiaotong University Beijing 100044 China

In this paper,we propose a new biased estimator of the regression parameters,the generalized ridge and principal correlation *** present its some properties and prove that it is superior to LSE(least squares estimator),principal correlation estimator,ridge and principal correlation estimator under MSE(mean squares error) and PMC(Pitman closeness) criterion,respectively.

关键词： linear regression model generalized ridge and principal correlation estimator mean squares error Pitman closeness criterion.