检索结果-南通市图书馆

Using a Gaussian mathematical model to define eruptive stages of young volcanic rocks in Tengchong based on laser 40Ar/39Ar dating

引用

Science China Earth Sciences 2020年第5期63卷 662-673页

作者： Xinwei ZHAO Jing ZHOU Fang MA Jianqing JI Alan DEINO School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking UniversityBeijing 100871China Berkeley Geochronology Center Berkeley CA94709USA

Reconstruction of Quaternary environments,late Cenozoic geodynamics and evaluation of volcanic hazards,all depend on the precise delineation of eruptive *** recent years,laser 40Ar/39Ar dating methods have been widely used for dating young volcanic rocks,given their stable automated testing process,very low background level and high sensitivity,which meet the requirements for precise dating of young *** paper applied high-precision laser 40Ar/39Ar dating to the main volcanic units in the Tengchong area and obtained ages in the range of 0.025–5.1 Ma using conventional data processing ***,conventional dating highlighted issues related to very low radiogenic 40Ar content,accidental errors and poor data stability,which led to huge age ***,lacking a unified timescale,conventional methods were unable to strictly define the stages of the Tengchong volcanic eruptions,leading to ongoing *** this study,we applied a Gaussian mathematical model to deal with all 378 original ages from 13 *** apparent age-probability diagram,consisting of three independent waveforms,have been *** corresponding isochron ages of these three waveforms suggest there were three volcanic eruptive stages,namely during the Pliocene(3.78±0.04 Ma),early Middle Pleistocene(0.63±0.03 Ma)and late Middle Pleistocene to early Late Pleistocene(0.139±0.005 Ma).These results accurately define eruptive stages in the Tengchong area.

关键词： Laser 40Ar/39Ar dating Gaussian mathematical model Eruptive stages Apparent age-probability diagram Age deviations Isochron age

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

Remaining Useful Life Prediction of Rolling Element Bearings Based on Different Degradation stages and Particle Filter

引用

Transactions of Nanjing University of Aeronautics and Astronautics 2019年第3期36卷 432-441页

作者： LI Qing MA Bo LIU Jiameng Beijing Key Laboratory of High?End Mechanical Equipment Health Monitoring and Self?recovery Beijing University of Chemical Technology

A method is proposed to improve the accuracy of remaining useful life prediction for rolling element bearings,based on a state space model(SSM)with different degradation stages and a particle *** model is improved by a method based on the Paris formula and the Foreman formula allowing the establishment of different degradation *** remaining useful life of rolling element bearings can be predicted by the adjusted model with inputs of physical data and operating status *** late operating trend is predicted by the use of the particle filter *** rolling bearing full life experimental data validate the proposed ***,the prediction result is compared with the single SSM and the Gamma model,and the results indicate that the predicted accuracy of the proposed method is higher with better practicability.

关键词： different life stages of state space model remaining useful life prediction of rolling element bearing particle filter

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

Quantitative division of succession and spatial patterns among different stand developmental stages in Changbai Mountains

引用

Journal of Mountain Science 2019年第9期16卷 2063-2078页

作者： GONG Zhi-wen KANG Xin-gang GU Li College of Economics and Management Research Center of Resource Economics and Environment Management Northwest A8J7 University Yangling 712100 China College of Forestry Northwest A&F University Yang ling 712100 China College of Forestry Beijing Forestry University Beijing 100083 China

Broadleaf-Korean pine forests exhibit high species richness and distinctive species composition, which are currently becoming more dominant among natural forests in Changbai Mountains of northeastern China. Understanding the ecological process of restored vegetation is quite important for ecosystem reconstruction. Distinguishing stand development stages and analyzing the dynamic spatial patterns could provide insights into significant community coexistence mechanisms. In the present study, eight permanent study areas were established according to the substituting space for time method in Changbai Mountains of north-eastern China. The optimal division method was used to quantify the successional series into different stand development stages, and the point pattern analysis method(L(r) function) was used to analyse the dynamic changes in spatial patterns and interspecific associations. Our results suggested that:(1) The stand development process was divided into five stages: the first three stages were poplar-birch secondary forests in different stages of recovery, the fourth stage was thespruce-fir mixed forest, and the last stage was the primary broadleaf-Korean pine forest;(2) The spatial pattern showed an aggregated distribution at a small scale and changed to a random distribution as the scale increased in poplar-birch secondary forests, but the spatial pattern appeared to be randomly distributed in spruce-fir mixed forest and broadleafKorean pine forest;(3) The interspecific associations between pioneer species and climax species changed from negative to positive among the different stand stages, and environmental resources were shared among these species. Interspecific differences in shade tolerance among the tree species were key determinants of forest dynamics and structure. Our study is vital to the understanding of the forest development;thus, the spatial change features should receive greater attention when forest management is being planned and restoratio

关键词： Dynamic spatial patterns Interspecific association Optimal division method Stand developmental stages Space for time substitution

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

Two stages of isotopic exchanges experienced by the Ertaibei granite pluton, northern Xinjiang, China

引用

Science China Earth Sciences 2000年第6期43卷 605-616页

作者：刘伟 Research Center for Mineral Resources Exploration Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100101 China

18O/16O and D/H of coexisting feldspar, quartz, and biotite separates of twenty samples collected from the Ertaibei granite pluton, northern Xinjiang, China are determined. It is shown that the Ertaibei pluton experienced two stages of isotopic exchanges. The second stage of18O/16O and D/H exchanges with meteoric water brought about a marked decrease in the δ18O values of feldspar and biotite from the second group of samples. The D/H of biotite exhibits a higher sensitivity to the meteoric water alteration than its18O/16O. However, the first stage of18O/16O exchange with the18O-rich aqueous fluid derived from the dehydration within the deep crust caused the Δ18OQuartz-Feldspar reversal. It is inferred that the dehydration-melting may have been an important mechanism for anatexis. It is shown that the deep fluid encircled the Ertaibei pluton like an envelope which serves as an effective screen to the surface waters.

关键词： two stages of isotopic exchange quartz-feldspar 18O/16O reversal dehydration-induced partial melting granite northern Xinjiang.

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

Effect of common salt on laboratory reared immature stages of Aedes aegypti(L)

引用

Asian Pacific Journal of Tropical Medicine 2010年第3期3卷 173-175页

作者： Mukhopadhyay AK Tamizharasu W Satya Babu P Goutam Chandra Hati AK National Institute of Communicable Diseases Regional Filaria Training & Research Center Department of Zoology The University of Burdwan School of Tropical Medicine

Objective:To observe the effect of common salt(NaCl) on immature stages of laboratory reared Aedes aegypti(L).Methods:A laboratory colony of Aedes aegypti mosquitoes of Rajahmundry strain was established in the laboratory of National Institute for Communicable Disease(NICD), Rajahmundry unit at(26±2)℃with relative humidity of(70±10)%.1.00%,1.25%and 1.50% solutions of common salt(NaCl) were selected to observe the susceptibility status of immature stages of Aedes aegypti in ***:Fifty percent larvae of Aedes aegypti died within 19,31 and 48 hours when exposed to 1.50%,1.25%and 1.00%common salt solution, *** percent of the larvae died within 29,57 and 108 hours when exposed to the same salt solutions,*** high pupal mortality was observed varying from 81.8% to 40.0%.Formation of pupae was found inversely proportional in the presence of concentration of common salt in breeding ***:With easy availability,less toxicity and long lasting nature,common salt may be applied in unused containers,especially in junkyards where surveillance mechanism is poor along with other conventional vector control methods in order to control breeding of Aedes aegypti,the vector of dengue/ dengue hemorrhagic fever and chikungunya.

关键词： Common salt Immature stages Aedes aegypti(L) Control

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

stages and Characteristics of Metropolitan Administrative Division Adjustment in China Since 1997

引用

China City Planning Review 2014年第3期23卷 6-14页

作者： Zhendong LUO Xin WANG Lei GENG School of Architecture and Urban Planning Nanjing University School of Architecture and Urban Planning Nan-jing University Research Institute of Urban Planning and Design Nanjing University

Administrative division adjustments(hereinafter referred to as ADA) proceed throughout China's rapid urbanization, especially during the process of metropolitanization. It has become an integral part of the transformation of China's urban and regional governance. Based on an analysis of ADA cases at the metropolitan level since 1997, this paper suggests that the stages and characteristics of ADA in China are closely related to the metropolitanization process. The internal dynamics and external constraints jointly created two stages of ADA at the metropolitan level in China, namely, a first stage from 1997 to 2007 and a second stage from 2008 to now. In the first stage, ADA primarily aimed at turning counties into districts, to meet the metropolis' demands for expansion. In the second stage, local governments laid equal stress on the two approaches of ADA, i.e., turning counties into districts and district restructuring. Such a change corresponded to the diversification of development demands of the metropolitan area. The evolution of ADA from the first stage to the second not only reflects the changing characteristics of metropolitanization at different times, but also demonstrates the viability of ADA as a means to improve the governance structure of the metropolitan area. ADA at the metropolitan level in China since 1997 basically accommodates the development of space and governance in the metropolitan area, which promotes the rapid development of a large metropolitan area.

关键词： metropolitan area administrative division adjustment(ADA) stages characteristics

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

Tolerance to Salinity of Sesame Genotypes in Different Phenological stages

引用

American Journal of Plant Sciences 2017年第8期8卷 1904-1920页

作者： Janivan Fernandes Suassuna Pedro Dantas Fernandes Marcos Eric Barbosa Brito Nair Helena Castro Arriel Alberto Soares de Melo Josely Dantas Fernandes Department of Biology State University of Paraiba UEPB Campina Grande Brazil Department of Agricultural Engineering Federal University of Campina Grande UFCG Campina Grande Brazil Department of Agricultural Science Federal University of Campina Grande UFCG Pombal Brazil Embrapa-Brazilian Agricultural Research Corporation Campina Grande Brazil Department of Agrobiology and Agriculture State University of Paraiba UEPB Lagoa Seca Brazil

The sesame crop is usually avoided in salt-affected areas because of the various effects of saline stress on plants. Besides varying between species, salinity effects are known to vary for genotypes of the same species as well as plant development stages. Thus, through the irrigation of plants with saline water, this study evaluates tolerance to saline stress of new sesame genotypes in different phenological stages. Three experiments were carried out under greenhouse conditions, using the sesame genotypes BRS Seda, LAG-927561 and LAG-26514. Water with different levels of electrical conductivity (ECw = 0.6, 1.6, 2.6, 3.6 and 4.6 dS m-1) was used to irrigate plants during germination and initial growth stages, as well as the entire crop cycle. Tolerance to saline stress (3.6 dS m-1) during growth and production stages was also studied. Salinity did not affect sesame germination, but seedling growth was hindered from the ECw of 1.6 dS m-1 onwards, and plant height was the most affected growth variable. Seed production is affected by salinity, regardless of the phenological stage in which plants are exposed to salinity. The strains LAG-927561 and LAG-26514 show promising signs in studies on adaptation to saline stress.

关键词： Sesamum indicum Development stages Saline Stress Relative Crop Yield

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

Chemical Composition and Antioxidant Activity of <i>Bunchosia glandulifera</i>Fruit at Different Ripening stages

引用

Food and Nutrition Sciences 2018年第10期9卷 1147-1159页

作者： Daiane Einhardt Blank Danize Justen Sara Fraga Carlos Roberto Peixoto Neusa Fernandes de Moura Natural Products Research Group Federal University of Rio Grande Santo Ant&ocirc nio da Patrulha Brazil

Bunchosia glandulifera belongs to the family Malpighiaceae and is popularly known as “caferana” in the city of Santo Antonio da Patrulha. The fruits have a high economic value and their inclusion in the diet has health benefits. They are natural sources of antioxidants because of the presence of bioactive compounds. However, their chemical composition can be influenced by the maturation process. This study aims to evaluate the changes in the bioactive antioxidant compounds in the pulp and seeds of B. glandulifera fruit during different stages of ripening. The fruits, were analyzed for caffeine, carotenoids, flavonoids, vitamin C, and total phenolic content as well as for antioxidant activity, at four different stages of ripening. An increase in bioactive compounds was observed from the second maturation stage to the ripened fruit, and the ripened fruit had the highest bioactive compound content. Phenolic compound and carotenoid levels were found to be highest in the pulp. Carotenoid content showed a positive correlation with the antioxidant activity. Colorimetric analysis also showed a high correlation between the levels of carotenoids and color change during the ripening stages.

关键词： Bunchosia glandulifera Ripening stages Caffeine Carotenoids Flavonoids Antioxidant Activity Vitamin C Phenolic Content

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

Qualitative and Quantitative Analysis of the Inorganic Materials Changes with Time in the stages of the Wastewater Treatment Plant

引用

Engineering（科研） 2012年第8期4卷 409-415页

作者： Falah Bani Hani Mohammad Abdallah Qasaimeh Ahmad Qasaimeh Civil Engineering Department Jerash University Jerash Jordan Department of Chemical Engineering Al-Huson University College Al-Balqa’ Applied University Salt Jordan

Due to the importance of the inorganic materials removal from wastewater, experimental and analytical study to the concentration change with time of these materials became essential. In this work, experimental analyses were performed to investigate the concentration changes of inorganic compounds during stages of activated sludge wastewater treatment plants at different sites in Jordan. The aim of this research is to examine the performance of the plants in treating pollutants and inorganic materials, and verify the quantitative and qualitative changes with time. Samples from the treatment stages were monthly taken and analyzed in the laboratory along a period of one year. The concentration changes of the inorganic solids in wastewater passing through treatment stages and aeration tank were recorded. Results show that the conventional treatment of the wastewater within different conditions in the year is not effective to decrease the concentrations of the inorganic compounds. Based on these results, we recommend adding tertiary advanced treatment unit in order to get acceptable water quality allowable to be reused for different purposes.

关键词： Water Treatment Inorganic Compounds Operational stages Concentration Changes

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

Study on the Effects of Extreme Precipitation for Seven Growth stages of Winter Wheat in Northern Weihe Loess Plateau, China

引用

Journal of Water Resource and Protection 2020年第4期12卷 358-380页

作者： Ouk Sereyrorth Baowen Yan Khem Chunpanha Porn Lybun Pich Linvolak College of Water Resources and Architectural Engineering Northwest A&F University Xianyang China Faculty of Hydrology and Water Resources Engineering Institute of Technology of Cambodia Phnompenh Cambodia

The research on the characteristic frequency of precipitation is a great significance for guiding regional agricultural planning, water conservancy project designs, and drought and flood control. Droughts and floods occurred in northern Weihe Loess Plateau, affecting growing and yield of winter wheat in the area. Based on the daily precipitation data of 29 meteorological stations from 1981 to 2012, this study is to address the analysis of three different frequencies of annual precipitation at 5%, 50%, and 95%, and to determine the amount of rainfall excess and water shortage during seven growth stages of winter wheat at 5%, 10%, and 20% frequencies, respectively. Pearson type III curve was selected for this study to analyze the distribution frequency of annual rainfall and rainfall amount following seven growth stages of winter wheat crop in 29 stations of Northern Weihe loess plateau. As a result of our study, annual precipitation is gradually increasing from southwest to northeast of Northern Weihe loess plateau. The highest amount of annual precipitation occurred in the Baoji area and the lowest precipitation covered by the northwest area of Northern Weihe loess plateau. Moreover, the amount of rainfall of seven growth stages indicates that excessive rainfall occurs not only in the first stage (sowing to tillering) and seventh stage (flowering to ripening) but also in second stage (tillering to wintering). In the seventh stage, a large amount of excessive rainfall occurred in Changwu, Bin, Qianyang, Fengxiang, Baojiqu, and Baojixian. Moreover, water shortage is distributed in the third stage (from wintering to greening), the fourth stage (from greening to jointing), the fifth stage (from jointing to heading), and the sixth stage (from heading to flowering). Furthermore, the worst water shortages occurred in Hancheng, Heyang, Chengcheng, Pucheng, Dali, Tongchuan, and Fuping in the fourth stage (greening to jointing stage). Even though we study the crop water requi

关键词： Extreme Precipitation Annual Precipitation Seven Growth stages Winter Wheat Crop Rainfall Excess Water Shortage Northern Weihe Loess Plateau

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：