期刊文献+
共找到313,517篇文章
< 1 2 250 >
每页显示 20 50 100
SleepyFlyR:An R Package for Sleep and Activity Analysis in Drosophila
1
作者 MOU Yang PING Yong 《Journal of Shanghai Jiaotong university(Science)》 2025年第4期744-750,共7页
Drosophila melanogaster has been a popular model organism in the study of sleep and circadian rhythm.The Drosophila activity monitoring(DAM)system is one of the many tools developed for investigating sleep behavior in... Drosophila melanogaster has been a popular model organism in the study of sleep and circadian rhythm.The Drosophila activity monitoring(DAM)system is one of the many tools developed for investigating sleep behavior in fruit flies and has been acknowledged by researchers around the world for its simplicity and cost-effectiveness.Based on the simple activity data collected by the DAM system,a wide range of parameters can be generated for sleep and circadian studies.However,current programs that analyze DAM data cover a limited number of metrics and fail to provide individual data for the user to plot graphs and conduct analysis using other software.Therefore,we have developed SleepyFlyR,an R package that:(1)is simple and easy to use with a user-friendly user interface script;(2)provides a comprehensive analysis of sleep and activity parameters;(3)generates double-plotted graphs for sleep and activity patterns;(4)offers visualization of sleep and activity profiles across multiple days or within a single day;(5)calculates the changes of sleep and activity parameters between baseline and experiment;(6)stores both summary data and individual data in files with unique title. 展开更多
关键词 Drosophila melanogaster SLEEP R package Drosophila activity monitoring(DAM)system behavioral analysis
原文传递
Preoperative butyrylcholinesterase activity and risk of postoperative delirium:A meta-analysis
2
作者 Yuan-Li Qiu Cheng Song +1 位作者 Cui-Wan Huang Wei-Gang Shen 《World Journal of Psychiatry》 2026年第1期385-399,共15页
BACKGROUND Postoperative delirium(POD)is a common and serious complication in surgical patients,particularly older adults.Alterations in cholinergic function have been implicated in its pathophysiology.AIM To evaluate... BACKGROUND Postoperative delirium(POD)is a common and serious complication in surgical patients,particularly older adults.Alterations in cholinergic function have been implicated in its pathophysiology.AIM To evaluate the association between preoperative serum cholinesterase(ChE)activity—specifically butyrylcholinesterase(BuChE)and acetylcholinesterase(AChE)—and the risk of POD in adult surgical patients in a meta-analysis.METHODS A systematic search was conducted in PubMed,EMBASE,and Web of Science up to March 28,2025 for studies reporting preoperative serum BuChE or AChE activity in relation to subsequent POD incidence.Standardized mean differences(SMDs)and odds ratios(ORs)with 95%confidence intervals(CIs)were pooled using random-effects models.Subgroup and sensitivity analyses were performed based on follow-up duration and analytic models.RESULTS Thirteen studies(n=2730 patients)were included.Patients who developed POD had significantly lower preoperative BuChE activity than those who did not(SMD=-0.28;95%CI:-0.39 to-0.16;I²=18%).Higher BuChE activity was associated with a reduced risk of POD(OR per 100 unit increment=0.97;95%CI:0.95-0.99;I2=0%).In contrast,pooled AChE activity did not differ significantly between POD and non-POD groups(SMD=-0.25;95%CI:-0.53 to 0.03;P=0.08;I2=80%),and the ORs per 1 unit increment in AChE activity were not statistically significant(OR=0.98;95%CI:0.95-1.01).CONCLUSION Lower preoperative serum BuChE activity is associated with an increased risk of POD in adults undergoing surgery.BuChE activity may serve as a potential preoperative biomarker for POD risk stratification. 展开更多
关键词 ACETYLCHOLINESTERASE BUTYRYLCHOLINESTERASE activity Postoperative delirium META-ANALYSIS
暂未订购
Conductive materials change the composition and activity of butyrate-degrading enrichment cultures with hydrogen as the main electron shuttle
3
作者 Cátia S.N Braga João C.Sequeira +5 位作者 M.SaloméDuarte Gilberto Martins Inês A.C.Pereira c Luciana Pereira M.Madalena Alves Andreia F.Salvador 《Journal of Environmental Sciences》 2026年第1期624-634,共11页
Conductive materials(CM)can improve methane production(MP)efficiency in many methanogenic systems.However,several types of CM exist,and there are uncertainties regarding whether they all improve MP efficiency to the s... Conductive materials(CM)can improve methane production(MP)efficiency in many methanogenic systems.However,several types of CM exist,and there are uncertainties regarding whether they all improve MP efficiency to the same extent and modulate microbial communities in a similar way.To investigate that,different microbial enrichments with and without activated carbon(AC),magnetite(Mag),and zeolites(Zeo)(at 0.5 g/L)were developed.MP profiles and microbial composition changes were compared among enrichments.The behavior of all enrichments was different,although the initial inoculum sludge was the same.Lag phase duration was lower in AC enrichment,while the complete conversion of butyrate to methane was faster in Mag enrichment.Syntrophomonas was the most abundant bacterial genus in all enrichments,but changes in the methanogenic community were evident.Acetoclastic methanogens were more diverse in Mag enrichment,with microorganisms assigned to Methanosarcina and Methanothrix gener1,but Methanothrix was the only acetoclastic methanogen in the other enrichments.On the other hand,different species of hydrogenotrophic methanogens prevailed in distinct enrichments.The metatranscriptomics results revealed that the dominant mechanism of interspecies electron transfer in the AC enrichment utilized hydrogen as the electron carrier,and no evidences of direct interspecies electron transfer(DIET)could be found.These results showed how different CM modulate microbial communities and affect MP efficiency through mechanisms that do not necessarily involve DIET or mediation via CM. 展开更多
关键词 BUTYRATE METHANE Anaerobic enrichments Activated carbon MAGNETITE Zeolites
原文传递
Abnormal regional spontaneous brain activity in major depressive disorder with obesity comorbidity:A resting-state functional magnetic resonance imaging study
4
作者 Xiao-Fang Hou Bo-Hui Mei +10 位作者 Xia Wang Fu-Tao Zhao Lei He Qian-Yu Chen Chen Zang Chong Wang Yu-Feng Tang Xiao-Xin Li Hui-Fang Zhang Na Wang Bing Cao 《World Journal of Psychiatry》 2026年第1期335-345,共11页
BACKGROUND Major depressive disorder(MDD)and obesity(OB)are bidirectionally comorbid conditions with common neurobiological underpinnings.However,the neurocognitive mechanisms of their comorbidity remain poorly unders... BACKGROUND Major depressive disorder(MDD)and obesity(OB)are bidirectionally comorbid conditions with common neurobiological underpinnings.However,the neurocognitive mechanisms of their comorbidity remain poorly understood.AIM To examine regional abnormalities in spontaneous brain activity among patients with MDD-OB comorbidity.METHODS This study adopted a regional homogeneity(ReHo)analysis of resting-state functional magnetic resonance imaging.The study included 149 hospital patients divided into four groups:Patients experiencing their first episode of drug-naive MDD with OB,patients with MDD without OB,and age-and sex-matched healthy individuals with and without OB.Whole-brain ReHo analysis was conducted using SPM12 software and RESTplus toolkits,with group comparisons via ANOVA and post-hoc tests.Correlations between ReHo values and behavioral measures were examined.RESULTS ANOVA revealed significant whole-brain ReHo differences among the four groups in four key regions:The left middle temporal gyrus(MTG.L),right cuneus,left precuneus,and left thalamus.Post-hoc analyses confirmed pairwise differences between all groups across these regions(P<0.05).OB was associated with ReHo alterations in the MTG.L,right cuneus,and left thalamus,whereas abnormalities in the precuneus suggested synergistic pathological mechanisms between MDD and OB.Statistically significant correlations were found between the drive and fun-seeking dimensions of the behavioral activation system,as well as behavioral inhibition and the corresponding ReHo values.CONCLUSION Our findings provide novel evidence for the neuroadaptive mechanisms underlying the MDD-OB comorbidity.Further validation could lead to personalized interventions targeting MTG.L hyperactivity and targeting healthy food cues. 展开更多
关键词 Neuroimage COMORBIDITY Brain activity OBESITY Major depression Regional spontaneous
暂未订购
Geographical differentiation of riverine DOM composition and source apportionment:A case study of a riverine network of a mountainous stream,a Plain River,and an artificial canal
5
作者 Jun-wei Zhao Shuang-bing Huang +2 位作者 Zhao-xin Su Wei-Chao Huang Yong Qian 《Journal of Groundwater Science and Engineering》 2026年第1期59-68,共10页
To elucidate the geographical differentiation characteristics and driving mechanisms of Dissolved Organic Matter(DOM)in typical rivers,this study conducted a multi-spectral investigation on three representative river ... To elucidate the geographical differentiation characteristics and driving mechanisms of Dissolved Organic Matter(DOM)in typical rivers,this study conducted a multi-spectral investigation on three representative river types within Shandong Province:The mountainous Dawen River,the plain Tuhai River,and the artificial East Grand Canal.The DOM composition was analyzed using Ultraviolet-Visible(UV-Vis)absorption spectroscopy,Excitation-Emission Matrix(EEM)fluorescence spectroscopy,and parallel factor analysis(PARAFAC),while Principal Component Analysis(PCA)was employed to quantify the synergistic effects of natural processes and anthropogenic activities.Results revealed significant spatial heterogeneity in DOM composition and sources.The plain river exhibited the highest aromaticity(humic-like components:43.3%)due to long-term agricultural non-point source inputs and urban wastewater discharge.The mountain stream,shaped by complex terrain and relatively intact ecosystems,was dominated by autochthonous DOM derived from microbial metabolism,with higher Fluorescence Index(FI=2.12)and biological index(BIX=1.35)than other river types.The artificial canal retained protein-like components(64.2%),largely attributed to winter hydrological stagnation and disturbances from shipping activities.Further analysis demonstrated that geographical settings(e.g.,mountain terrain)and anthropogenic activities(e.g.,agriculture,shipping)jointly regulated DOM composition by altering the balance between input and transformation processes.Integrated fluorescence parameters and PCA results suggested differentiated management strategies:protecting ecological integrity in mountain streams to sustain selfpurification,enhancing non-point source interception in plain rivers,and mitigating shipping pollution in canals.This study systematically reveals the natural-anthropogenic coupling mechanisms driving DOM dynamics in northern China rivers,providing critical insights for precision water environment management at the watershed scale. 展开更多
关键词 Dissolved organic matter(DOM) UV-Vis spectroscopy Parallel factor analysis(PARAFAC) Geographical settings Anthropogenic activities
在线阅读 下载PDF
Association of FADS2 polymorphism rs174538 with fatty acid metabolism and disease severity in Japanese patients with Crohn’s disease
6
作者 Hideyuki Matsuzawa Zensho Ito +11 位作者 Kan Uchiyama Yutaro Motoi Yuichiro Ohtaki Yuko Iwashita Shizuka Suzuki Tatsuya Nakada Shigeo Koido Kana Kojima Kota Murohashi Masayuki Saruta Toshifumi Ohkusa Takahiro Kubota 《World Journal of Gastroenterology》 2026年第2期114-123,共10页
BACKGROUND Crohn’s disease(CD)is a chronic inflammatory bowel disease with unknown etiology.Inflammatory chemical mediators synthesized from arachidonic acid,an n-6 polyunsaturated fatty acid(PUFA),have been shown to... BACKGROUND Crohn’s disease(CD)is a chronic inflammatory bowel disease with unknown etiology.Inflammatory chemical mediators synthesized from arachidonic acid,an n-6 polyunsaturated fatty acid(PUFA),have been shown to activate CD.Additionally,n-3 PUFAs are metabolized by the same enzyme as n-6 PUFAs and known to inhibit the arachidonic acid cascade.Our previous study noted that the presence of erythrocyte membrane fatty acids is a characteristic finding in Japanese CD patients.It was thus speculated that FADS2 gene polymorphisms,which induce PUFA metabolizing enzymes,are involved in the pathogenesis of CD,though no such relationship was found.AIM To investigate the relationship of FADS2 polymorphisms with serum and erythrocyte membrane fatty acid composition ratios,and disease activity.METHODS Using previously reported findings regarding FADS2 genetic polymorphisms,the records of 52 CD patients undergoing treatment at Jikei University Kashiwa Hospital were analyzed.Mutations noted were divided into three groups;wild-type(GG),heterozygous mutants(GA),and homozygous(AA),with the activities of delta-6 and delta-5 desaturases compared using redefined d6d index(rd.d6di)and d5d index(d5di).Additionally,comparisons of serum and erythrocyte membranes for fatty acid composition,and also gene polymorphisms and CD activity index(CDAI)were performed.RESULTS The presence of the rs174538 mutation in FADS2 resulted in reduction of only rd.d6di in the erythrocyte membrane(P<0.01).In contrast,that mutation was found to be associated with d5di induced by FADS1 in serum(P=0.019)as well as the erythrocyte membrane(P<0.0001),and also with reduction in the fatty acid composition of arachidonic acid in both serum(P<0.0001)and the erythrocyte membrane(P<0.01).Regarding disease activity,a positive correlation of CDAI score with rd.d6di in both serum(P<0.05)and the erythrocyte membrane(P<0.05)was found only in the rs174538 wild-type group.In contrast,there was no correction between CDAI and d5di in either serum or erythrocyte membrane samples.CONCLUSION The rs174538 mutation alters the fatty acid profile through strong linkage to the FADS1 gene.In wild-type individuals,rd.d6di was positively correlated with CDAI,suggesting predictive utility of disease severity. 展开更多
关键词 Crohn’s disease FADS2 gene rs174538 FADS1 gene Crohn’s disease activity index
暂未订购
Experimental Verification of Intrinsic Pressure Framework in an Activity Landscape
7
作者 Zihao Sun Longfei Li +6 位作者 Chuyun Wang Jing Wang Huaicheng Chen Gao Wang Fangfu Ye Liyu Liu Mingcheng Yang 《Chinese Physics Letters》 2026年第1期322-326,共5页
The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence... The intrinsic pressure framework,which treats self-propelling force as an external force,provides a convenient and consistent description of mechanical equilibrium in active matter.However,direct experimental evidence is still lacking.To validate this framework,here we employ a programmable robotic platform,where a single light-controlled wheeled robot travels in an activity landscape.Our experiments quantitatively demonstrate that the intrinsic pressure difference across the activity interface is balanced by the emerged polarization force.This result unambiguously confirms the theoretical predictions,thus validating the intrinsic pressure framework and laying the experimental foundation for the intrinsic pressure-based mechanical description of dry active matter. 展开更多
关键词 intrinsic pressure framework activity landscape intrinsic pressure difference robotic platform programmable robotic platformwhere self propelling force polarization force mechanical equilibrium
原文传递
Illusion of inactivity:Revisiting progressive multiple sclerosis treatment paradigms
8
作者 Tal Ganz Tamir Ben-Hur 《Neural Regeneration Research》 2026年第3期1134-1135,共2页
Active inflammation in“inactive”progressive multiple sclerosis:Traditionally,the distinction between relapsing-remitting multiple sclerosis and progressive multiple sclerosis(PMS)has been framed as an inflammatory v... Active inflammation in“inactive”progressive multiple sclerosis:Traditionally,the distinction between relapsing-remitting multiple sclerosis and progressive multiple sclerosis(PMS)has been framed as an inflammatory versus degenerative dichotomy.This was based on a broad misconception regarding essentially all neurodegenerative conditions,depicting the degenerative process as passive and immune-independent occurring as a late byproduct of active inflammation in the central nervous system(CNS),which is(solely)systemically driven. 展开更多
关键词 inflammatory versus degenerative dichotomythis treatment paradigms illusion inactivity multiple sclerosis traditionallythe central nervous system cns which progressive multiple sclerosis active inflammation progressive multiple sclerosis pms
暂未订购
Characterization of apparent sulfur oxidation activity of thermophilic archaea in bioleaching of chalcopyrite 被引量:5
9
作者 朱薇 夏金兰 +2 位作者 彭安安 聂珍媛 邱冠周 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第8期2383-2388,共6页
The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi (JCM 8954), Metallosphaera sedula (YN 23), Acidianus manzaensis (YN 25) and Sulfolobus metallicus (YN 24) and the... The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi (JCM 8954), Metallosphaera sedula (YN 23), Acidianus manzaensis (YN 25) and Sulfolobus metallicus (YN 24) and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable. 展开更多
关键词 thermophilic archaea sulfur oxidation activity CHARACTERIZATION BIOLEACHING
在线阅读 下载PDF
Toxicity and Antifeedant Activity of Extracts from Walnut Green Husk against Wheat Aphid
10
作者 梁永锋 《Plant Diseases and Pests》 CAS 2010年第4期36-38,共3页
[Objective] The research aimed to study the toxicity and antifeedant activity of walnut green husk extract on wheat aphid. [Method] Using ultrasonic extraction, 5 kinds of different polarity solvents were used to prep... [Objective] The research aimed to study the toxicity and antifeedant activity of walnut green husk extract on wheat aphid. [Method] Using ultrasonic extraction, 5 kinds of different polarity solvents were used to prepare the extracts from walnut green husk. The toxicity and antifeedant activity on wheat aphid were determined, [ Result ] Walnut green husk extracts in the solvent of ethanol, acetone, ethyl acetate had higher toxicity and antifeedant activity on wheat aphid. When the concentration was 100 mg/ml, after 24 h, the toxicity and antifeedant activity of three kinds extracts on wheat aphid were greater than 84.35% and 66.98%, respectively. After 48 h, the toxicity and antifeedant activity were greater than 85.91% and 79.34%, respectively. Among 5 kinds extracts,ethanol extracts had the highest toxicity and antifeedant activity on wheat aphid. After 24 h, the corrected mortality rate was 93.64% and the antifeedant rate was 83.61%. After 48 h,the corrected mortality rate was 94.95% and antifeedant rate was 92.21%. Petroleum ether extract had the smallest toxicity and antifeedant activity on wheat aphid. After 24 h,the corrected mortality rate and antifeedant rate were 19.54% and 34.65%, respectively. After 48 h,the corrected mortality rate and antifeedant rate were 20.13% and 39. 03%, respectively. [ Conclsion] The extracts from walnut green husk with larger polarity solvent had better toxicity and higher antifeedant activity on wheat aphid. 展开更多
关键词 Walnut green husk EXTRACTS Wheat aphid Biological activity STUDIES
在线阅读 下载PDF
Study on the Insecticidal and Antifeedant Activity of Extracts from Portulaca oleracea L. on Aphis sp.
11
作者 梁永锋 《Agricultural Science & Technology》 CAS 2008年第4期137-140,共4页
[Objective] The experiment studied on insecticidal and antifeedant action of on Portulaca oleracea L.to provide theoretical basis for developing a new botanical insecticide by taking Portulaca oleracea L.as a raw mate... [Objective] The experiment studied on insecticidal and antifeedant action of on Portulaca oleracea L.to provide theoretical basis for developing a new botanical insecticide by taking Portulaca oleracea L.as a raw material.[Method] The insecticidal activities of the ethanol extracts and 5 kinds of extracts with petroleum ether,chloroform,ethyl acetate,n-butanol,water from Portulaca oleracea L..against Aphis sp.was studied;Leaves are using drug treatments of 5 extracts anti-feedant activity of Aphis sp.[Result] The results showed that 95% ethanol extract displayed high contact activity to Aphis sp.The corrected mortality after 48 h reached 95.4 % under the concentration of 50.00 mg·ml-1 and the insecticidal activities of 5 extracts against Aphis sp.was in the order that petroleum ether > chloroform > n-butanol > ethyl acetate >water.Five kinds of anti-feeding activity in the extract of the order for the water> ethyl acetate> n-butanol > chloroform >petroleum ether.[Conclusion] The extract from Portulaca oleracea L.has a strong contact toxicity of pesticide active on Aphis sp.substances and for a small polar compounds,the strong anti-feeding activity is a kind of larger polar compounds. 展开更多
关键词 PORTULACA OLERACEA L.extract AphiS sp. Poisoned Anti-feeding activity Research
在线阅读 下载PDF
Sphingomyelin synthase activity measurement by the fluorescent product in cell culture medium or animal plasma 被引量:1
12
作者 丁庭波 董继斌 +1 位作者 楼滨 蒋宪成 《Journal of Chinese Pharmaceutical Sciences》 CAS CSCD 2014年第4期256-261,共6页
Sphingolipids, a new class of lipid mediators, are involved in a variety of important physiological and pathological processes. Sphingomyelin synthase (SMS) is an enzyme to convert the ceramide (Cer.) and phosphat... Sphingolipids, a new class of lipid mediators, are involved in a variety of important physiological and pathological processes. Sphingomyelin synthase (SMS) is an enzyme to convert the ceramide (Cer.) and phosphatidylcholine into sphingomyelin (SM) and diacylglycerol, which plays a key role in sphingolipid biosynthesis. Two SMS isoforms, SMS1 and SMS2, have been identified with different subceUular localizations and expression level in tissues. Previous studies have shown that SMS may serve as a potential therapeutic target for the treatment of various diseases, such as cardiovascular and metabolic diseases. Thus, there is an urgent need for a rapid and sensitive method for SMS activity analysis. In our study, we developed a novel method for SMS activity by monitoring the appearance of the product, NBD-SM, in the tissue culture medium or blood and applied this method in cells and mice. In Huh7 cells, the interassay coefficient of variation of the SMS activity assay was (3.60±0.07)% . In wild type (WT) mice, we observed accumulation of NBD-SM in blood in a time dependent fashion. In SMS2 KO mice, NBD-SM in plasma collected at 5- (0%, P〈0.01), 30- (16%, P〈0.01), and 60 min (21%, P〈0.01) after injection of fluorescence liposome solution was significantly decreased compared with WT mice. However, in SMS1 KO mice, NBD-SM in plasma collected 5- and 30 min is similar to that in WT mice. Our results suggest that this method could be used for SMS activity measurement in vitro and in vivo. 展开更多
关键词 Sphingomyelin synthase SMS activity assay SMS inhibitor screening SphiNGOMYELIN CERAMIDE
原文传递
Bipolarins A–H, eight new ophiobolin-type sesterterpenes with antimicrobial activity from fungus Bipolaris sp. TJ403-B1 被引量:4
13
作者 LIU Meng-Ting HE Yan +2 位作者 SHEN Ling HU Zheng-Xi ZHANG Yong-Hui 《Chinese Journal of Natural Medicines》 SCIE CAS CSCD 2019年第12期935-944,共10页
Bipolarins A–H(1–8), eight new tetracyclic ophiobolin-type sesterterpenes featuring a rare oxaspiro[4.4]nonane moiety, were isolated from cultures of fungus Bipolaris sp. TJ403-B1. Their structures and absolute conf... Bipolarins A–H(1–8), eight new tetracyclic ophiobolin-type sesterterpenes featuring a rare oxaspiro[4.4]nonane moiety, were isolated from cultures of fungus Bipolaris sp. TJ403-B1. Their structures and absolute configurations were elucidated by comprehensive spectroscopic analyses, single-crystal X-ray diffraction experiments, electronic circular dichroism and 13 C NMR calculations. Additionally, compound 5 exhibited significant selective antimicrobial activity against Enterococcus faecalis with an MIC value 8 μg·mL^-1. 展开更多
关键词 Bipolaris sp. Ophiobolins SESTERTERPENES Antimicrobial activity
原文传递
基于Phi29 DNA聚合酶的新酶挖掘及表征 被引量:1
14
作者 郝梦瑶 胡玲玲 +4 位作者 韩明昊 李从雨 常宏 骆健美 江会锋 《生物工程学报》 北大核心 2025年第1期427-436,共10页
近年来,噬菌体Φ29(Phi29)DNA聚合酶因其具有恒温高保真扩增的能力,成为热点关注对象。为了进一步推进这类等温聚合酶的工业化应用,本研究将已表征的Phi29 DNA聚合酶序列针对微生物宏基因组进行新酶挖掘与表征。在植物宿主群体的宏基因... 近年来,噬菌体Φ29(Phi29)DNA聚合酶因其具有恒温高保真扩增的能力,成为热点关注对象。为了进一步推进这类等温聚合酶的工业化应用,本研究将已表征的Phi29 DNA聚合酶序列针对微生物宏基因组进行新酶挖掘与表征。在植物宿主群体的宏基因组中,鉴定出一种新酶——Php29 DNA聚合酶,该酶具有更高的链置换活性(与噬菌体Φ29的相似度达到59.5%)。实验验证结果表明,该酶也具备3ʹ→5ʹ核酸外切酶活性,其扩增产物可用于进一步的催化反应。Php29 DNA聚合酶的挖掘和验证为未来等温扩增酶的工业化应用提供了有益参考。 展开更多
关键词 新酶挖掘 phi29 DNA聚合酶 异源表达 滚环扩增 核酸外切酶活性
原文传递
GIS-Based Analysis of Relative Tectonic Activity along the Kazerun Fault Zone, Zagros Mountains, Iran: Insights from Data Mining of Geomorphic Data 被引量:2
15
作者 Ali Faghih Ahmad Nourbakhsh Timothy M.Kusky 《Journal of Earth Science》 SCIE CAS CSCD 2015年第5期712-723,共12页
This paper tests a data mining method for evaluation of the "IRTA"(Index of Relative Tectonic Activity) to investigate the impact of active tectonics on geomorphic processes and landscape development. Based upon K... This paper tests a data mining method for evaluation of the "IRTA"(Index of Relative Tectonic Activity) to investigate the impact of active tectonics on geomorphic processes and landscape development. Based upon K-means clustering of six basin-related geomorphic indices(the hypsometric integral, basin asymmetric factor, drainage density, basin shape ratio, mean axial slope of the channel and topographic roughness) that represent the relative strength of active tectonic deformation on topography and morphology, the relative tectonic activity along the Kazerun Fault Zone in the Zagros Mountains of Iran may be classified into low, moderate and high relative tectonic activity zones. The results allow the identification of the clusters of similarly deformed areas related to relative tectonic activity. The utilization of geomorphic parameters as well as IRTA with comparison to the field observations exhibit change in relative tectonic activities mostly corresponding to the change in mechanism of the prominent fault zones in the study area. 展开更多
关键词 active tectonics geomorphic index K-means clustering Kazerun Fault Zone ZAGROS Iran
原文传递
Antioxidant Activity <i>in Vitro</i>of Polysaccharide Extracted by Ultrasound with Different Powers from <i>Ophiopogon japonicas</i> 被引量:2
16
作者 Xiaomei Wang Tianzhu Zhang +3 位作者 Wenfei Zhang Mingming Zhang Songqi Zhu Haibo Liu 《American Journal of Plant Sciences》 2018年第9期1826-1834,共9页
The polysaccharides were extracted by different power ultrasound from Ophiopogon japonicas. The extraction yield and in vitro antioxidant activities including scavenging effect on hydroxyl radical, superoxide anion fr... The polysaccharides were extracted by different power ultrasound from Ophiopogon japonicas. The extraction yield and in vitro antioxidant activities including scavenging effect on hydroxyl radical, superoxide anion free radicals and DPPH were investigated. The results showed that with the increase of ultrasonic power, the yield of the polysaccharides decreased first and then increased. The antioxidant activity of polysaccharides increased first and then decreased with the increase of ultrasonic power. When the power was 400 W, the scavenging effect on superoxide anion and DPPH of the polysaccharides was the strongest, and the scavenging ability of hydroxyl radical was the strongest when the power was 560 W. Therefore, different ultrasonic power could affect the extraction yield and antioxidant activity of Ophiopogon japonicas polysaccharide. It will provide theoretical basis and experimental support for the application of ultrasonic extraction on polysaccharides from Ophiopogon japonicas. 展开更多
关键词 ULTRASOUND Ophiopogon japonicas Antioxidant activity
暂未订购
Separation and Anti-Hantaan Virus Activity of Extracts from Alternanthera philoxcroides in vitro and in vivo 被引量:2
17
作者 LIU Yingjuan YANG Zhanqiu DENG Haiying XIAO Hong QU Chunfeng 《Wuhan University Journal of Natural Sciences》 CAS 2007年第6期1143-1147,共5页
A water-soluble substance was extracted from the Chinese herb, Alternantheraphiloxcroides with hot water and alcohol. Aliquots of this initial extract were further fractionated by treatment with ether, ethyl acetate a... A water-soluble substance was extracted from the Chinese herb, Alternantheraphiloxcroides with hot water and alcohol. Aliquots of this initial extract were further fractionated by treatment with ether, ethyl acetate and alcohol respectively. The four extracts were assayed for anti-viral activity against three serum, Hantaan virus 114 (HV114), HV435 and A9 strains. Results show that the four extracts are capable of inhibiting Hantaan virus propagation, of which extract No. 1 has the best efficiency. The three dosage of extract No. 1, which are used upon three Hantaan virus serum IC50, are 153, 157, 154 μg/mL. New-born mice were made to be infected with HV114 and then fed in vivo with extract No.l on the 3rd, 10th and 14th days after being infected by the virus. The treatment continued for 8 days with a dosage of 2.5 g/kg. Result shows that survival rates of mice were 75%, 50% and 0, respectively. The median time to death (MTDs) of the three groups were 37, 30, 23 days. 展开更多
关键词 antiviral activity Alternanthera philoxcroides Hantaan virus cell culture animal experiment
暂未订购
Characterization of Aroma-Active Components and Antioxidant Activity Analysis of E-jiao(Colla CoriiAsini)from Different Geographical Origins 被引量:11
18
作者 Shan Zhang Lu Xu +3 位作者 Yang-Xi Liu Hai-Yan Fu Zuo-Bing Xiao Yuan-Bin She 《Natural Products and Bioprospecting》 CAS 2018年第2期71-82,共12页
E-jiao(Colla Corii Asini,CCA)has been widely used as a healthy food and Chinese medicine.Although authentic CCA is characterized by its typical sweet and neutral fragrance,its aroma components have been rarely investi... E-jiao(Colla Corii Asini,CCA)has been widely used as a healthy food and Chinese medicine.Although authentic CCA is characterized by its typical sweet and neutral fragrance,its aroma components have been rarely investigated.This work investigated the aroma-active components and antioxidant activity of 19 CCAs from different geographical origins.CCA extracts obtained by simultaneous distillation and extraction were analyzed by gas chromatography-mass spectrometry(GC-MS),gas chromatography-olfactometry(GC-O)and sensory analysis.The antioxidant activity of CCAs was determined by ABTS and DPPH assays.A total of 65 volatile compounds were identified and quantified by GC-MS and 23 aroma-active compounds were identified by GC-O and aroma extract dilution analysis.The most powerful aroma-active compounds were identified based on the flavor dilution factor and their contents were compared among the 19 CCAs.Principal component analysis of the 23 aroma-active components showed 3 significant clusters.Canonical correlation analysis between antioxidant assays and the 23 aroma-active compounds indicates strong correlation(r=0.9776,p=0.0281).Analysis of aroma-active components shows potential for quality evaluation and discrimination of CCAs from different geographical origins. 展开更多
关键词 Colla Corii Asini Aroma-active compounds Antioxidant activity CHEMOMETRICS
暂未订购
Conductive Polyaniline/Cellulose/Graphite Composite Films with High Thermal Stability and Antibacterial Activity 被引量:7
19
作者 JingHuan Chen JinGang Liu +3 位作者 WenTao Zhang Kun Wang XueRen Qian RunCang Sun 《Paper And Biomaterials》 2017年第1期40-51,共12页
Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide mon... Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications. 展开更多
关键词 CELLULOSE GRAphiTE POLYANILINE conductive film thermal stability antibacterial activity
在线阅读 下载PDF
Single Nucleotide Polymorphism of CYP3A4 Intron 2 and Its Influence on CYP3A4 mRNA Expression and Liver Enzymatic Activity in Human Liver 被引量:2
20
作者 黄敏 王汉明 +4 位作者 郭瑜 平洁 陈曼 徐丹 汪晖 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2015年第4期502-507,共6页
Summary: In adult liver, CYP3A4 plays an important role in the metabolism of a wide range of en- dogenous and exogenous compounds. To investigate whether there is a single nucleotide polymorphism (SNP) of CYP3A4 in... Summary: In adult liver, CYP3A4 plays an important role in the metabolism of a wide range of en- dogenous and exogenous compounds. To investigate whether there is a single nucleotide polymorphism (SNP) of CYP3A4 intron 2 in the liver and its effects on the mRNA expression and enzymatic activity of CYP3A4, genomic DNA was extracted from 96 liver tissue samples obtained from patients who had undergone liver surgery. An SNP of CYP3A4 intron 2 was identified by polymerase chain reaction (PCR)-single-strand confirmation polymorphism and DNA sequencing. The mRNA expression of CYP3A4 was determined by the fluorescence quantitative PCR technique. The enzymatic activity of CYP3A4 was measured using erythromycin and testosterone as probe substrates. Twelve patients were found to have the SNP/T4127G CYP3A4 within intron 2. The mRNA levels of CYP3A4 in wild-type and SNP/T4127G samples were 2.62±1.09 and 2.79±1.63, respectively (P〉0.05). Erythromycin N-demethylase activity in wild-type and SNP/T4127G samples were 121.2±32.8 and 124.7±61.6 nmol·mg^-1min^-1, respectively (P〉0.05). The activity of testosterone 613-hydroxylase was significantly different between wild-type (648±173 pmol·mg^-1·min^-1) and SNP/T4127G samples (540-4-196 pmol.mg-l-minl; P〈0.05). In conclusion, the SNP/T4127G of CYP3A4 intron 2 exists in the liver. This SNP does not affect the mRNA expression of CYP3A4 but significantly decreases the hepatic micro- somal testosterone 613-hydroxylase activity of CYP3A4. Furthermore, this study indicates that the ap- propriate selection of probe substrates is very important in studying the relationship between the geno- type and phenotype of CYP3A4. 展开更多
关键词 CYP3A4 single nucleotide polymorphism mRNA expression enzymatic activity human liver
暂未订购
上一页 1 2 250 下一页 到第
使用帮助 返回顶部