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Search Results: 1 - 10 of 78295 matches for " Youqiang Chen "
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Fluorescence Detection and Discrimination of ss- and ds-DNA with a Water Soluble Oligopyrene Derivative
Youqiang Chen,Gaoquan Shi
Sensors , 2009, DOI: 10.3390/s90604164
Abstract: A novel water-soluble cationic conjugated oligopyrene derivative, oligo(N1,N1,N1,N4,N4,N4-hexamethyl-2-(4-(pyren-1-yl) butane-1,4-diaminium bromide) (OHPBDB), was synthesized by a combination of chemical and electrochemical synthesis techniques. Each oligomer chain has five pyrene derivative repeating units and brings 10 positive charges. OHPBDB showed high and rapid fluorescence quenching in aqueous media upon addition of trace amounts of single-stranded (ss) and double-stranded (ds) DNA. The Stern-Volmer constants for ss- and ds-DNA were measured to be as high as 1.3 × 108 mol-1·L and 1.2 × 108 mol-1·L, respectively. On the other hand, distinct fluorescence enhancement of OHPBDB upon addition of large amount of ss-DNA or ds-DNA was observed. Furthermore, ss-DNA showed much stronger fluorescence enhancement than that of ds-DNA, thus yielding a clear and simple signal useful for the discrimination between ss- and ds-DNA in aqueous media.

Zhu Jinmao,Chen Youqiang,

植物生态学报 , 1998,
Abstract: The quantitative characteristics and size class of populations of Castanopsis fargesii and Schima superba in northern Fujian province were analyzed in this paper.The results indicate that both of them were Pioneer populations in the area where disturbance by human beings took place in evergreen broad leaved forests.The disturbance of medium level by human being might enhance the development of C.fargesii population.,while,both lack of disturbance and strong, frequent human disturbance would limit the developmentof C.fargesii population.The S.superba population kept relatively steady in communities under natural disturbance,and its important value and proportion of higher size class increased.Disturbance by human beings restricted S.superba population and increased the proportion of lower size class. The more frequent disturbance by human occurred,the more difficultly S.superba population developed.

Chen Youqiang,Ye Bingying,Gao Yiping,Chen Wenlie,

植物科学学报 , 2000,
Abstract: 用焦锑酸钾沉淀的电镜细胞化学方法,研究了低温胁迫下枇杷幼叶细胞内Ca^2+水平变化。研究结果表明,枇杷幼叶细胞未经低温处理时,Ca^2+定位分布的沉淀颗凿在碍出现在细胞壁、细胞间隙、质膜和液泡;叶绿体、细胞质和细胞核中也有一些Ca^2+沉淀颗粒分布。楷杷幼叶经44h、4℃低温处理后,在质膜和液泡膜上Ca^2+沉淀颗粒分布。枇杷幼叶经44h、4℃低处理后,在质膜和液泡膜上Ca^2+的沉淀增多,细胞质
Construction of Saccharomyces cerevisiae mutant with knockout of SNF4 gene

Xiaohua Lin,Chongrong Ke,Bisha Wu,Yongbiao Zheng,Li Li,Youqiang Chen,Jianzhong Huang,

生物工程学报 , 2011,
Abstract: Construction and ethanol production effects of SNF4 gene knockout in Saccharomyces cerevisiae were described in this paper.For knockout of SNF4 gene in S.cerevisiae YS2,a PCR-amplified disruption cassette was used,encoding the short flanking homologous regions to the SNF4 gene and Kanr as selectable marker.The SNF4 gene disruption cassette was transformed into S.cerevisiae YS2 through LiAc/SS Carrier DNA/PEG.The positive transformants were grown on G418 plates and verified by PCR.The Kanr marker was rescued...
Geochemical characteristics and petrogenesis of the quartz syenite porphyry from Tongchang porphyry Cu(Mo-Au) deposit in Jinping County,Yunan Province

XU LeiLuo,BI XianWu,SU WenChao,QI YouQiang,LI Liang,CHEN YouWei,DONG ShaoHua,TANG YongYong,

岩石学报 , 2011,
Abstract: The Tongchang porphyry Cu(Mo-Au) deposit is located in southern segment of the Jinshajiang-Red River alkali-rich intrusive belt.The Tongchang quartz syenite porphyry intrusion is one important member of the Jinshajiang-Red River alkali-rich intrusions.Detailed geochemical study on the Tongchang quartz syenite porphyries indicates that it is characterized by high alkali,metaluminous to weakly peraluminous and enrichment in potassium,and belongs to shoshonitic rock.These rocks are obviously enriched in LILEs(...
Tectonic Setting of the Cu-Ni Sulfide-Bearing Mafic-Ultramafic Complexes in Northern Jilin Province, NE China  [PDF]
Dacheng Jia, Shen Liu, Hong Zhong, Guangying Feng, Youqiang Qi, Wen Gao, Xiao Zhang, Tao Jiang, Yongxin Mao
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.42030

There are series of Cu-Ni sulfide-bearing mafic-ultramafic intrusions widespread in north JilinProvince,Northeastern China. The intrusions formed in Xing’an-Mongolian Orogenic Belt near to the northeastern margin of North China Craton. The complexes were formed in almost same period according to the zircon U-Pb dating reported recently, which means that the complexes were formed in same tectonic period and belong to one tectonic magmatic event. The rock assemblages are different from the ophiolite type and Yidun type in orogenic belt. The mafic-ultramafic complexes formed in the range from 217 Ma to 232 Ma coeval with A-type granites in the area, which formed bimodal igneous rock assemblage. According to the regional angular unconformities, there were existed the orogenies of Caledonian, Hercynian, Early Indosinian, Late Indosinian and Yanshanian. The Early Indosinian coeval with orogenic I-type granites and sanukitie that suggesting the lithosphere thickening in the extrusion tectonic setting of orogenic processes, however the Late Indosinian coeval with bimodal igneous rock assemblage that suggesting the lithosphere thinning in the extension tectonic setting of post-orogenic processes in the Xing’an-Mongolian Orogenic Belt. Chemical composition of the mafic-ultramafic rocks has the characteristics of high-Mg and low-K tholeiites related with inter-continental post-orogenic tectonic setting. The trace elements indicate their formed in conditions of continental extension belt or initial rift and has the characteristics of revolution from

Improved Synthesis of 5-Substituted 1H-Tetrazoles via the [3+2] Cycloaddition of Nitriles and Sodium Azide Catalyzed by Silica Sulfuric Acid
Zhenting Du,Changmei Si,Youqiang Li,Yin Wang,Jing Lu
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044696
Abstract: A silica supported sulfuric acid catalyzed [3+2] cycloaddition of nitriles and sodium azide to form 5-substituted 1 H-tetrazoles is described. The protocol can provide a series of 5-substituted 1 H-tetrazoles using silica sulfuric acid from nitriles and sodium azide in DMF in 72%–95% yield.
Liangzhu Huang,Youqiang Li,Dongmei Gao,Zhenting Du
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812014158
Abstract: In the title compound, C18H15NO4, the benzene rings form quite different dihedral angles [16.07 (1) and 59.50 (1)°] with the central pyrrole ring, indicating a twisted molecule. Conjugation is indicated between the five- and six-membered rings by the lengths of the C—C bonds which link them [1.462 (3) and 1.477 (3) ]. The most prominent feature of the crystal packing is the formation of inversion dimers via eight-membered {...HNCO}2 synthons.
U-Pb Zircon Age, Geochemical and Sr-Nd Isotopic Constraints on the Age and Origin of the Granodiorites in Guilong, Southeastern Yunnan Province, Southern China  [PDF]
Shen Liu, Ruizhong Hu, Caixia Feng, Shan Gao, Guangying Feng, Youqiang Qi, Tao Wang, Ian M. Coulson, Yuhong Yang, Chaogui Yang
Open Journal of Geology (OJG) , 2012, DOI: 10.4236/ojg.2012.24023
Abstract: Post-collision felsic rocks in Southeastern Yunnan province contain granodiorites. U-Pb zircon ages, geochemical data and Sr-Nd isotopic data for these rocks are reported in the present paper. Laser ablation inductively coupled plasma mass spectrometry U-Pb zircon analyses yielded consistent age 252.5 ± 1.0 Ma for one sample of the felsic rocks. The granodiorites were characterized by variational and high (87Sr/86Sr)i, ranging from 0.7223 to 0.7236 and very low εNd (t) values from –29.1 to –30.4. In addition, these rocks are characterized by slight Eu negative anomalies, Nb, Ta, Ti and Sr negative anomalies on primitive mantle normalization spider. Geochemical and isotopic characteristics suggest that these rocks were derived from an enriched crust source. The granodiorites resulted from the fractionation of potassium feldspar, plagioclase and ilmenite or rutile. However, the granodiorites were unaffected by visible crustal contamination during ascent. As a result, the granodiorites may have been formed due to partial melting of crust-derived sedimentary rocks beneath southeastern Yunnan province, southern China.
Efficient 2,3-Butanediol Production from Cassava Powder by a Crop-Biomass-Utilizer, Enterobacter cloacae subsp. dissolvens SDM
Ailong Wang, Youqiang Xu, Cuiqing Ma, Chao Gao, Lixiang Li, Yu Wang, Fei Tao, Ping Xu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040442
Abstract: Background 2,3-Butanediol (BD) is considered as one of the key platform chemicals used in a variety of industrial applications. It is crucial to find an efficient sugar-utilizing strain and feasible carbon source for the economical production of BD. Methodology/Principal Findings Efficient BD production by a newly isolated Enterobacter cloacae subsp. dissolvens SDM was studied using crop-biomass cassava powder as substrate. The culture conditions and fermentation medium for BD production were optimized. Under the optimal conditions, 78.3 g l?1 of BD was produced after 24 h in simultaneous saccharification and fermentation (SSF), with a yield of 0.42 g BD g?1 cassava powder and a specific productivity of 3.3 g l?1 h?1. A higher BD concentration (93.9 g l?1) was produced after 47 h in fed-batch SSF. Conclusions/Significance The results suggest that strain SDM is a good candidate for the BD production, and cassava powder could be used as an alternative substrate for the efficient production of BD.
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