检索结果-南通市图书馆

Mechanism of ultrasonic strengthening fluidity of low mature shale oil: A case study of the first member of Lucaogou Formation, western Jimusaer Sag, Northwest China

引用

Petroleum Science 2023年第6期20卷 3337-3347页

作者： Bo-Yang wang Bo Liu Yun-Fei Cui zi-long wang Key Laboratory of Continental Shale Hydrocarbon Accumulation and Efficient Development Ministry of EducationNortheast Petroleum UniversityDaqing163318HeilongjiangChina No.203 Exploration Team Jilin Bureau of Coalfield GeologySiping136000JilinChina

The low mature shale oil resources of Lucaogou Formation in Jimusar Sag have a great potential, but the heavy oil quality limits large-scale economic development significantly. Ultrasonic is a typical representative of heavy oil viscosity reduction and anhydrous fracturing technology, and how to understand the action characteristics and mechanism of ultrasonic effect on reservoir is a critical issue to enhance shale oil production in the industrialized application of power ultrasonic. Therefore, the comparative experiments with different time of power ultrasonic loading were conducted to analyze the response mechanism of reservoir characteristics and the change of fluid mobility. The results indicate that the ultrasonic treatment is ameliorative to the pore-fracture structure, and the improvement degree is controlled by the mechanical vibration and cavitation of ultrasound. Generally, the location with weak cementation strength or relatively developed microcrack is preferred to pore expansion. After the ultrasonic treatment, the shale oil quality becomes lighter, and the transformation of shale oil from adsorbed to free, is accelerated due to enhanced fluidity. Pore-expanding effect and fluid mobility enhancement are essential aspects of the power ultrasonic loading to improve the recovery of low mature shale oil. The results of this study support the feasibility analysis of ultrasonic enhanced shale oil exploitation theoretically.

关键词： Ultrasonic Shale oil Reservoir properties Mobility Recovery

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

Preparation and properties of hot-deformed magnets processed from nanocrystalline/amorphous Nd-Fe-B powders

引用

Rare Metals 2021年第8期40卷 2033-2039页

作者： Peng Zhao Yang Luo Dun-Bo Yu Hai-Jun Peng Wen-long Yan zi-long wang Xin-Yuan Bai National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsBeijing100088China Grirem Advanced Materials Co. LtdBeijing100088China

The hot-deformed magnets processed from nanocrystalline/amorphous Nd-Fe-B powders were preparedunderdifferenthot-pressingtemperatures(600-750℃,at intervals of 25℃)by the self-made hotpressing *** microstructure and magnetic properties of hot-deformed magnets prepared at different temperatures were also *** the temperature is above 650℃,the density of magnet reaches 7.5 g·cm^(-3).The optimum magnetic properties of magnetic induction intensity of B_(r)=1.3 T,optimum energy product of(BH)_(max)=282.5 kJ·m^(-3),intrinsiccoercivityof H_(cj)=1130.0 kA·m-1 of hot-deformed magnets are obtained at hot-pressing temperature of 650℃.X-ray diffractometer pattern shows that the(00 L)texture has been *** the microstructural characteristic,on the one hand,the good magnetic performance is attributed to the fine platelet-like grains with an average length of 410-440 nm at the hot-pressing temperature range from625 to 675℃.On the other hand,the unaligned coarse grains are observed in all the *** the areal fraction of those is gradually increasing with the rise of the hot-pressing temperature,which tends to deteriorate the magnetic *** composition map shows the accumulation of Nd/Pr-rich phase in the coarse grains’region.

关键词： Nanocrystalline/amorphous powders Hotpressing temperature Hot-deformed Magnets Magnetic properties Microstructure

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

csd alleles in the red dwarf honey bee （Apis florea, Hymenoptera： Apidae） show exceptionally high nucleotide diversity

引用

Insect Science 2011年第6期18卷 645-651页

作者： Zhi-Yong Liu zi-long wang Xiao-Bo Wu Wei-Yu Yan Zhi-Jiang Zeng Honeybee Research Institute Jiangxi Agricultural University Experimental Animal Center Institute of Occupational Disease Prevention Nanchang China

The single locus complementary sex determination （sl-csd） gene is the primary gene determining the gender of honey bees （Apis spp.）. While the csd gene has been well studied in the Western honey bee （Apis mellifera）, and comparable data exist in both the Eastern honey bee （Apis cerana） and the giant honey bee （Apis dorsata）, no studies have been conducted in the red dwarf honey bee, Apisflorea. In this study we cloned the genomic region 3 of the A. florea csd gene from 60 workers, and identified 12 csd alleles. Analysis showed that similar to A. mellifera, region 3 of the csd gene contains a RS domain at the N terminal, a proline-rich domain at the C terminal, and a hypervariable region in the middle. However, the A. florea csd gene possessed a much higher level of nucleotide diversity, compared to A. mellifera, A. cerana and Apis dorsata. We also show that similar to the other three Apis species, in A. florea, nonsynonymous mutations in the csd gene are selectively favored in young alleles.

关键词： balancing selection complementary sex determination csd allele nucleotidediversity polymorphism positive selection

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

Simultaneous switching of supramolecular chirality and organizational chirality driven by Coulomb expansion

引用

Nano Research 2022年第6期15卷 5316-5321页

作者： Ming-Xia Shi Jiyu Xu Kai Sun Min-long Tao Ji-Yong Yang Da-Xiao Yang zi-long wang Zuo Li Jun-Zhong wang Qi-Kun Xue Sheng Meng School of Physical Science and Technology Southwest UniversityChongqing 400715China Institute of Physics Chinese Academy of SciencesBeijing 100190China Department of Physics Tsinghua UniversityBeijing 100084China

Chiral switching is a fascinating topic and plays an important role in construction of ***,due to the complexity and flexibility of noncovalent interactions,switching the chirality of entire supramolecular assemblies has hitherto remained a *** we report the electric field-controlled chirality switching of pentacene pinwheel arrays and two-dimensional(2D)network *** molecules on Cd(0001)surface form the porous network structure with building blocks of hexamer *** by the electric field from a scanning tunneling microscopy(STM)tip,the supramolecular chirality of pentacene pinwheels and the organizational chirality of entire network domains can be simultaneously switched from one enantiomorph to ***,such chiral switching is reversible and repeatable under successive voltage ***-principles calculations demonstrate that electric field significantly modulates the interfacial charge transfer and induces the Coulomb expansion of pentacene layers,and the subsequent reaggregation leads to the chiral flipping of the supramolecular pinwheels and 2D *** results provide a new strategy for dynamic control of the 2D chiral structures and help to steer the supramolecular assembly toward homochirality.

关键词： network switched expansion

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

Structure and magnetic properties of melt-spun Sm-Fe-Nb ribbons and their nitrides

引用

Rare Metals 2018年第3期37卷 232-236页

作者： Wen-long Yan Yang Luo Dun-Bo Yu Gui-Yong Wu Ning-Tao Quan Yuan-Fei Yang Hai-Jun Peng zi-long wang National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsGrirem Advanced Materials Co. Ltd.

SmFe（10-x）Nbx（x = 0, 0.1, 0.2, 0.3） ribbons and their nitrides were prepared by melt-spinning, followed by annealing and subsequent nitriding. The structure and magnetic properties were investigated by means of X-ray diffraction（XRD） using the Rietveld method, vibrating sample magnetometer（VSM）, transmission electron microscope（TEM） and Mossbauer spectroscopy. XRD analysis shows that the addition of Nb can impede the precipitation of Sm2 Fe（17） and a-Fe phases and the Nb atoms occupy 2 e site in the alloys. At 300 K, the mean hyperfine fields of 2 e site are 29.58 T with Nb doping at x = 0.1 and the corresponding Curie temperature is 552 K. The optimal properties of remanence of Br = 0.9 T, intrinsic coercivity of H（cj）= 741.5 kA·m^-1, and maximum magnetic energy product of（BH）（max）= 124.2 kJ·m-（-3） are gained at x = 0.10 in the nitrides.

关键词： Melt-spinning SmFe10-xNbx powders Magnetic properties XRD Rietveld Mssbauer spectroscopy

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 highly selective C-rhamnosyltransferase from Viola tricolor and insights into its mechanisms

引用

Acta Pharmaceutica Sinica B 2023年第8期13卷 3535-3544页

作者： Bo-Yun Han zi-long wang Junhao Li Qing Jin Hao-Tian wang Kuan Chen Yang Yi Hansgren Xue Qiao Min Ye State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical SciencesPeking UniversityBeijing 100191China Department of Physics and Astronomy Uppsala UniversityUppsala SE-75120Sweden College of Life Science Anhui Agricultural UniversityHefei 230036China Peking University-Yunnan Baiyao International Medical Research Center Beijing 100191China

C-Glycosides are important natural products with various *** plant biosynthetic pathways,the C-glycosylation step is usually catalyzed by C-glycosyltransferases(CGTs),and most of them prefer to accept uridine 5’-diphosphate glucose(UDP-Glc)as sugar *** CGTs favoring UDP-rhamnose(UDP-Rha)as sugar donor has been reported,thus ***,we report the first selective C-rhamnosyltransferase VtCGTc from the medicinal plant Viola *** could efficiently catalyze C-rhamnosylation of 2-hydroxynaringenin 3-C-glucoside,and exhibited high selectivity towards *** for the sugar donor selectivity of VtCGTc were investigated by molecular dynamics(MD)simulations and molecular mechanics with generalized Born and surface area solvation(MM/GBSA)binding free energy ***144 played a vital role in recognizing UDP-Rha,and the V144T mutant could efficiently utilize *** work provides a new and efficient approach to prepare flavonoid C-rhamnosides such as violanthin and iso-violanthin.

关键词： Flavonoid C-glycoside C-rhamnosyltransferase Biosynthesis Catalytic mechanisms Sugardonorselectivity

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

The integrative analysis of microRNA and mRNA expression in Apis mellifera following maze-based visual pattern learning

引用

Insect Science 2014年第5期21卷 619-636页

作者： Qiu-Hong Qin zi-long wang Liu-Qing Tian Hai-Yan Gan Shao-Wu Zhang Zhi-Jiang Zeng Honeybee Research Institute Jiangxi Agricultural University Nanchang China ARC Center of Excellence in Vision Science Research School of Biology The Australian National University Canberra ACT Australia

The honeybee （Apis mellifera） is a social insect with strong sensory capacity and diverse behavioral repertoire and is recognized as a good model organism for studying the neurobiological basis of learning and memory. In this study, we analyzed the changes in microRNA （miRNA） and messenger RNA （mRNA） following maze-based visual learning using next-generation small RNA sequencing and Solexa/lllumina Digital Gene Expression tag profiling （DGE）. For small RNA sequencing, we obtained 13 367 770 and 13 132 655 clean tags from the maze and control groups, respectively. A total of 40 differentially expressed known miRNAs were detected between these two samples, and all of them were up-regulated in the maze group compared to the control group. For DGE, 5 681 320 and 5 939 855 clean tags were detected from the maze and control groups, respectively. There were a total of 388 differentially expressed genes between these two samples, with 45 genes up-regulated and 343 genes down-regulated in the maze group, compared to the control group. Additionally, the expression levels of 10 differentially expressed genes were confirmed by quantitative reverse transcription polymerase chain reaction （qRT-PCR） and the expression trends of eight of them were consistent with the DGE result, although the degree of change was lower in amplitude. The integrative analysis of miRNA and mRNA expression showed that, among the 40 differentially expressed known miRNAs and 388 differentially expressed genes, 60 pairs of miRNA/mRNA were identified as co-expressed in our present study. These results suggest that both miRNA and mRNA may play a pivotal role in the process of learning and memory in honeybees. Our sequencing data provide comprehensive miRNA and gene expression information for maze-based visual learning, which will facilitate understanding of the molecular mechanisms of honeybee learning and memory.

关键词： Apis mellifera Y-maze learning and memory microRNA DGE differential expression

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

Permanent magnetic properties of Nd-Fe-B melt-spun ribbons with Y substitution

引用

Rare Metals 2020年第1期39卷 55-61页

作者： Cao-Huan Zhang Yang Luo Dun-Bo Yu Ning-Tao Quan Gui-Yong Wu Ya-Kun Dou Zhou Hu zi-long wang National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsBeijing100088China Grirem Advanced Materials Co.Ltd Beijing100088China

Phase constituents,microstructures and magnetic properties of melt-spun Nd12-xYxFe81B6 Nb ribbons were investigated *** influence of Y substitution for Nd on the phase stability,grain size and magnetic exchange coupling was *** is found that all the ribbons crystallize in the tetragonal 2:14:1 structure,i.e.,with single hard magnetic phase at the roll speed of25 m *** the increase in Y doping,Curie temperature(Tc)increases,while the coercivity decreases monoclinic ***,remanence magnetization(Br)and maximum energy product((BH)max)fluctuate and the maximum value is obtained at certain amount of *** optimum magnetic properties of intrinsic coercivity of intrinsic coercivity(Hcj)=908.2 kA·m-1 and(BH)max=118.52 kJ·m-3 are achieved when x=*** can be attributed to the strengthened exchange coupling between the neighboring nanograins in Nd-Y-Fe-B meltspun powder based on the Henkel ***,Y substitution also significantly improves the temperature stability of magnetic *** coercivity temperature coefficient ofβ=-0.157%·℃-1 and remanence temperature coefficient ofα=-0.32%·℃-1 are gained,which are greatly reduced compared with those of the undoped Nd-Fe-B compounds.

关键词： Rapid quenching (Nd,Y)-Fe-B alloy Exchange coupling Thermal stability

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

An Ideal Hallmark Closest to Complete Cure of Chronic Hepatitis B Patients:High-sensitivity Quantitative HBsAg Loss

引用

Journal of Clinical and Translational Hepatology 2023年第1期11卷 197-206页

作者： zi-long wang Jia-Rui Zheng Rui-Feng Yang Lin-Xiang Huang Hong-Song Chen Bo Feng Peking University People’s Hospital Peking University Hepatology InstituteBeijing Key Laboratory of Hepatitis C and Immunotherapy for Liver DiseasesBeijingChina

In the era of antiviral therapy,the main goal of treatment has shifted from the persistent inhibition of hepatitis B virus(HBV)replication to the pursuit of serological clearance of HBs surface antigen(HBsAg).Based on the life cycle of HBV,HBsAg originates from covalently closed circular DNA(cccDNA)and integrated HBV DNA,thus reflecting their transcriptional *** HBsAg loss may mean elimination or persistent inactivity of the HBV genome including cccDNA and integrated HBV *** loss improves the recovery of abnormal immune function,which in turn,may further promote the clearance of residual *** with functional cure and the great improvement of clinical outcomes,the continuous seroclearance of high-sensitivity quantitative HBsAg may represent the complete cure of chronic hepatitis B(CHB).For many other risk factors besides HBV itself,patients with HBsAg loss still need regular *** this review,we summarized the evolution of CHB treatment,the origin of serum HBsAg,the pattern of HBsAg seroclearance,and the effect of HBsAg loss on immune function and disease *** addition,we discuss the significance of high-sensitivity HBsAg detection and its possibility as a surrogate of complete cure.

关键词： Hepatitis B virus Chronic hepatitis B HBsAg Immunoassay Functional cure Complete cure Biomarker

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

Lower alanine aminotransferase levels are associated with increased all-cause and cardiovascular mortality in nonalcoholic fatty liver patients

引用

World Journal of Hepatology 2023年第6期15卷 813-825页

作者： Jia-Rui Zheng zi-long wang Su-Zhen Jiang Hong-Song Chen Bo Feng Peking University Hepatology Institute Peking University People's HospitalBeijing 100044China

BACKGROUND Serum alanine aminotransferase(ALT) levels are often considered a marker to evaluate liver disease and its *** To investigate the association between ALT levels and all-cause and cause-specific mortality in patients with nonalcoholic fatty liver disease(NAFLD).METHODS The Third National Health and Nutrition Examination Survey(NHANES-Ⅲ) from 1988 to 1994 and NHANES-Ⅲ-related mortality data from 2019 onward were used to obtain the necessary data for the study. NAFLD was defined as hepatic steatosis, as diagnosed by ultrasound, with no other liver diseases. ALT levels were categorized into four groups according to the different recommended upper limits of normal(ULN) in men and women: < 0.5 ULN, 0.5-1 ULN, 1-2 ULN, and ≥ 2 ULN. The hazard ratios for all-cause mortality and cause-specific mortality were analyzed using the Cox proportional hazard *** Multivariate logistic regression analysis demonstrated that the odds ratio of NAFLD correlated positively with increased serum ALT levels. In patients with NAFLD, all-cause mortality and cardiovascular mortality were the highest when ALT was < 0.5 ULN, yet cancer-related mortality was the highest when ALT was ≥ 2 ULN. The same results could be found in both men and women. Univariate analysis showed that severe NAFLD with normal ALT levels had the highest allcause and cause-specific mortality, but the difference was not statistically significant after adjustment for age and multivariate *** The risk of NAFLD was positively correlated with ALT level, but all-cause and cardiovascular mortality were the highest when ALT was < 0.5 ULN. Regardless of the severity of NAFLD, normal or lower ALT levels were associated with higher mortality than elevated ALT levels. Clinicians should be aware that high ALT levels indicate liver injury, but low ALT levels are associated with a higher risk of death.

关键词： Non-alcoholic fatty liver disease Alanine aminotransferase Mortality NHANES-Ⅲ

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：