检索结果-南通市图书馆

The Pleistocene vermicular red earth in South China signaling the global climatic change: The molecular fossil record

引用

Science China Earth Sciences 2003年第11期46卷 1113-1120页

作者：谢树成易轶刘育燕顾延生马振兴林文姣王先彦刘刚梁斌朱宗敏 Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Institute of Geological Survey of Jiangxi Province Nanchang 330201 China

The trace molecular fossils identified in the Pleistocene vermicular red earth by using the gas chromatography-mass spectrometry (GC/MS) analysis include n-alkanes, n-alkanoic acids, n-alkanols and n-alkan-2-ones. The variations of the n-alkane parameters appear to bear signifi-cant climate information, in striking contrast to the oxygen-bearing molecules (n-alkanoic acids and n-alkanols) believed to be more easily reworked by post-depositional processes. Of importance in paleoclimate reconstruction are the ratios of C27/C31 n-alkane indicative of the replacement of woody plants by grassy vegetation, and C15—21/C22—33 n-alkane representative of the relative abun-dance between microorganisms and higher plants. The profile trends of the two n-alkane ratios are comparable to the marine oxygen isotope record among stages 4—20. These molecular fossil re-cords implicate that the Pleistocene vermicular red earth widespread in South China was formed in coupling to the global climatic change and could be an important climate carrier.

关键词： biomarker, paleosol, paleoclimate, molecular stratigraphy, molecular paleontology, Quaternary, China.

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

Selective chemical degradation of kerogen from Nenjiang Formation of the southern Songliao Basin

引用

Science China Earth Sciences 2007年第10期50卷 1504-1509页

作者： XIONG YongQiang WANG YongQuan WANG YanMei State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640China State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640China State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640China

A sequential selective chemical degradation has been performed on the kerogen from the Nenjiang Formation of the southern Songliao Basin by using a series of mild chemical degradations (alkaline hydrolysis, cleavage of ether-bonds and sulfur-bonds, and ruthenium tetroxide (RuO4) oxidation). Subsequently, the GC-MS analyses are carried out on different degradation products. The results show that chemical degradations can release a great number of GC/MS-determinable biomarkers from insoluble kerogen, such as, alkaline hydrolysis products mainly comprise n-alkanes, fatty acids and alkanols; thiophene compounds are predominantly ether-bound to kerogen matrix; the products from the cleavage of sulfur-sulfur and sulfur-carbon bonds in the kerogen include fatty acids, alkanols and some n-alkanes with high carbon numbers; RuO4 oxidation products are predominantly monocarboxylic acids and α,ω-dicarboxylic acids. The distributions of main degradation products indicate that organic matter in this kerogen is predominantly derived from algae and bacteria, and that small amounts of high plant-derived organic matter are possibly combined into kerogen matrix at the late stage by sulfur bonds and other means. This study will provide an important approach for further discussing sources of organic matter in source rocks and their depositional paleoenvironments.

关键词： kerogen, selective chemical degradation, biomarker, Songliao basin

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

Distributions of fatty acids in a stalagmite related to paleoclimate change at Qingjiang in Hubei,southern China

引用

Science China Earth Sciences 2005年第9期48卷 1463-1469页

作者： XIE Shucheng1,HUANG Junhua1,WANG Hongmei2,YI Yi1,HU Chaoyong1, CAI Yanjun3 & CHENG Hai4 1. Faculty of Earth Science,China University of Geosciences,Wuhan 430074,China 2. School of Environmental Studies,China University of Geosciences,Wuhan 430074,China 3. SKLLQG,Institute of Earth Environment,Chinese Academy of Sciences,Xi’an 710075,China 4. Department of Geology and Geophysics,University of Minnesota,MN55455,USA 1. Faculty of Earth Science China University of Geosciences 430074 Wuhan China 2. School of Environmental Studies China University of Geosciences 430074 Wuhan China 3. SKLLQG Institute of Earth Environment Chinese Academy of Sciences 710075 Xi’an China 4. Department of Geology and Geophysics University of Minnesota 55455 MN USA

Fatty acids extracted from a subtropical stalagmite at Qingjiang in Southern China’s Hubei Province were analysed using gas chromatography-mass spectrometry. These n-alkanoic acids range from C14 to C26 in carbon number, maximizing at C16, with a second dominance at C22. In contrast to the stalagmite analysed, the overlying soils are characterized by the dominance of heavy-molecular-weight homologues (>C20). The n-fatty acids in the stalagmite were proposed to be contributed by both the soil ecosystems and the microbes harboring in the percolating water and the cave. The ratios of unsaturated to saturated n-fatty acids (C16:1i/C16:0, C18:1/C18:0) appear to show trends comparable with the oxygen isotope records of the stalagmite carbonate, with enhanced values associated with the cold episode such as Heinrich event 1. This paleoclimate-dependent record of the n-fatty acids might reflect microbial changes in physiology and activity in response to the temperature. This record shows somewhat difference from the previous paleoclimate signal extracted from n-alkanols and n-alkan-2-ones of the same stalagmite. The acid record fails to document the well-known Younger Dryas event which was effectively shown by the latter two biomarkers derived from soil ecosystems. This discrepancy might result from the changing biogeochemical impact on different lipid fractions as well as the varied organism populations in different ecosystems.

关键词： biomarker, ecosystem, microbe, speleothem, paleoclimate, Quaternary.

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

Isolation of Cell-Free DNA from Seminal Fluid

引用

Journal of Pharmacy and Pharmacology 2017年第8期5卷 554-560页

作者： Tina Draskovic Faculty of Pharmaciy University of Ljubljana Ljubljana 1000 Slovenia

Cell-flee DNA （cfDNA） is small short double stranded molecule that is also found in seminal fluid. It is a product ofapoptotic cells in different developmental stages during spermatogenesis. To final concentration of total cfDNA in semen contributesalso cfDNA secreted from living cells and cfDNA that is result of different diseases e.g. prostate cancer or infertility. Amendedconcentration （high or low） can be connected to prostate cancer or male infertility and can represent important non-invasive diagnosticbiomarker for detection and prognosis of these pathological conditions. In this paper, I will discuss different approaches for isolation ofcfDNA from seminal fluid, which includes selection of the samples, separation, isolation, extraction, purification and analysis. Today＇smost popular approach for isolation is the use of commercial kits based on selective binding and elution on silica-membrane technology,magnetic-bead technology or extraction with organic solvents and salting out procedure. Furthermore I will present that I tried to isolatecfDNA from semen with QIAamp DNA Mini Kit to confirm the presence of cell-free DNA in our samples. In the end I will describeproblems we are facing during cfDNA measurement which are mainly associated with low concentration of cfDNA in samples.

关键词： Cell-free DNA, seminal fluid, diagnostic biomarker, prostate cancer, male infertility, cell-free DNA isolation, problems ofcell-free DNA measurement.

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

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

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：