检索结果-南通市图书馆

Griseofulvin enantiomers and bromine-containing griseofulvin derivatives with antifungal activity produced by the mangrove endophytic fungus Nigrospora ***1

引用

Marine Life Science & Technology 2024年第1期6卷 102-114页

作者： Ge Zou Wencong Yang Tao chen Zhaoming Liu Yan chen Taobo Li gulab Said Bing Sun Bo Wang Zhigang She School of chemistry Sun Yat-sen UniversityGuangzhou 510275China State Key Laboratory of Applied Microbiology Southern china Guangdong Provincial Key Laboratory of Microbial Culture Collection and ApplicationInstitute of MicrobiologyGuangdong Academy of SciencesGuangzhou 510070China School of Pharmacy Anhui Medical UniversityHefei 230032China Department of chemistry Women University SwabiSwabi 23430Pakistan

Marine microorganisms have long been recognized as potential sources for drug *** was one of the first antifungal natural products and has been used as an antifungal agent for *** this study,12 new griseofulvin derivatives[(±)-1-2,(+)-3,(±)-4,10-12,and 14-15]and two new griseofulvin natural products(9 and 16)together with six known analogues[(-)-3,5-8,and 13]were isolated from the mangrove-derived fungus Nigrospora ***1 treated with 0.3%Nacl or 2%NaBr in rice solid *** 2D structures and absolute configurations were established by extensive spectroscopic analysis(1D and 2D NMR,HRESIMS),EcD spectra,computational calculation,DP4+analysis,and X-ray single-crystal *** 1-4 represent the first griseofulvin enantiomers with four absolute configurations(2S,6'S;2R,6'R;2S,6'R;2R,6'S),and compounds 9-12 represent the first successful production of brominated griseofulvin derivatives from fungi via the addition of NaBr to the culture *** the antifungal assays,compounds 6 and 9 demonstrated significant inhibitory activities against the fungi colletotrichum truncatum,Microsporum gypseum,and Trichophyton mentagrophyte with inhibition zones varying between 28 and 41 mm(10μg/disc).The structure-activity relationship(SAR)was analyzed,which showed that substituents at c-6,c-7,c-6'and the positions of the carbonyl and double bond of griseofulvin derivatives significantly affected the antifungal activity.

关键词： Mangrove endophytic fungus Nigrospora sp. Griseofulvin Antifungal activity

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

The kilosecond variability of X-ray sources in nearby galaxies

引用

Research in Astronomy and Astrophysics 2013年第12期13卷 1445-1454页

作者： Soma Mandal Ranjeev Misra gulab c.Dewangan Department of Physics Taki Government College Inter-University centre for Astronomy and Astrophysics

chandra observations of 17 nearby galaxies were analyzed and 166 bright sources with X-ray counts 〉 100 were chosen for temporal analysis. Fractional root mean square （rms） variability amplitudes were estimated for light curves, binned at 4 kilosecond （ks）, with length 〈 40 ks. While there are nine ultra-luminous X- ray sources （ULXs） with unabsorbed luminosity （in the 0.3-8.0 keV band） L 〉 1039 erg s-1 in the sample for which the fractional rms variability is constrained to be 〈 10%, only two of them show variability. One of the variable ULXs exhibits a secular transition and has an ultra-soft spectrum with temperature - 0.3 keV while the other is a rapidly varying source in NGc 0628, which has previously been com- pared to the Galactic microquasar GRS 1915＋105. These results seem to indicate that ULXs are typically not highly variable on ks timescales, except for some ultra-soft ones. Among the relatively low luminosity sources （L - 10^38 erg s-1）, we find five of them to be variable. Apart from an earlier known source in NGc 1569, we identify a source in NGc 2403 that exhibits persistent high amplitude fluctuations. In general, the variability of the sources does not seem to be correlated with hardness, which indicates that they may not be due to variations in any absorbing material, but instead could reflect instabilities in the inner accretion disk.

关键词： galaxies: general --X-rays: binaries

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

Broad-band spectral study of LMXB black hole candidate 4U 1957+11 with NuSTAR

引用

Research in Astronomy and Astrophysics 2021年第9期21卷 11-20页

作者： Prince Sharma Rahul Sharma chetana Jain gulab c.ewangan Anjan Dutta Department of Physics and Astrophysics University of DelhiDelhi 110007India Hansraj college University of DelhiDelhi 110007India Inter-University centre for Astronomy and Astrophysics(IUcAA) Pune411007India Indian Institute of Science Education and Research(IISER)Mohali Punjab140306India

We present here the results of broadband spectral analysis of a low-mass X-ray binary and a black hole candidate 4 U 1957+*** source was observed nine times with the Nuclear Spectroscopic Telescope A rray(NuSTAR)between September 2018 and November *** these observations,the spectral state of 4 U 1957+11 evolved *** disc dominant spectra are described well with a hot,multicolor disc blackbody with disc temperature varying in the range kT_(in)~1.35-1.86 keV and a non-thermal component having a steep slope(Γ=2-3).A broad Fe emission line feature(5-8 keV)was observed in the spectra of all the *** relativistic disc model was used to study the effect of distance,inclination and the black hole mass on its *** indicate a higher spin for smaller distances and lower black hole *** smaller distances and higher masses,spin is maximum and almost independent of the *** inverse correlation exists between the spin and the spectral hardening factor for all the *** system prefers a moderate spin of about 0.85 for black hole masses between 4-6 M⊙for a 7 kpc distance.

关键词： accretion,accretion discs black hole physics X-rays:binaries X-rays:individualU 1957+11

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

Long-Term Effects of Different Passages of Vehicular Traffic on Soil Properties and carbon Storage of a crosby Silt Loam in USA

引用

Pedosphere 2019年第2期29卷 150-160页

作者： gulab Singh YADAV Rattan LAL Ram Swaroop MEENA Basant RIMAL carbon Management and Sequestration centre the Ohio State University

The passage of vehicles with heavy axle loads causes soil compaction, and this adversely affects soil properties and crop *** adverse effects can persist for several years due to significant changes in key soil properties. However, the mechanisms of the aforementioned effects are not well understood for conservation agriculture(cA)(e.g., no-till(NT)) wherein the use of heavy machinery is considerably common. Therefore, known compaction forces(0 Mg load for compaction(NT-0, control), two passages of 2.5 Mg water wagon axle load(NT-2), and four passages of 2.5 Mg water wagon axle load(NT-4)) were applied to all the plots annually for 20 consecutive years. The experiment was established in 1997 at the Waterman Agricultural and Natural Resources Laboratory(WANRL), Ohio State University, columbus, Ohio. Each treatment was replicated thrice. Soil samples were obtained in November2016 to determine the effects of variations in the axle load and vehicular passages on carbon(c) and nitrogen(N) storage and selected soil properties of a crosby silt loam soil under NT-based corn-soybean rotation with residue retention in central Ohio, USA. Three locations were also randomly selected in an adjoining natural woodlot(WL) soil plot and sampled(30 m away from the compaction field) to compare the effects of vehicular traffic on soil under NT with WL soil. Results revealed that soil bulk density(ρb) and total porosity at 0–10 and 10–20 cm depths were not affected by the passages of vehicular traffic for 20 years under the NT *** penetration resistance(PR)(1.86 and 2.03 MPa at 0–10 and 10–20 cm soil depths, respectively) was significantly higher under NT-4 compared with that under other treatments. Saturated hydraulic conductivity at 0–10 and 10–20 cm soil depths ranged from19.7 to 31.4 and 18.5 to 29.5 mm d^(-1), respectively, across all the treatments. The proportion of macroaggregates(> 0.25 mm) and microaggregates(c mean diam

关键词： carbon stock heavy machinery no-till residue retention soil aggregates soil compaction soil quality well-drained soil

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

UV and X-ray variability of the narrow-line Seyfert 1 galaxy Ark 564

引用

Research in Astronomy and Astrophysics 2016年第7期16卷 69-76页

作者： Savithri H.Ezhikode gulab c.Dewangan Ranjeev Misra Shruti Tripathi Ninan Sajeeth Philip Ajit K.Kembhavi Department of Physics St. Thomas College Kozhencherry Kerala 689641 India Inter-University centre for Astronomy & Astrophysics Post Bag 4 Ganeshkhind Pune 411 007 India Physics Department Bishop's University 2600 College Street Sherbrooke QC J1M1Z7 Canada

We analyze eight XMM-Newton observations of the bright Narrow Line Seyfert 1 galaxy Arakelian 564（Ark 564）. These observations, separated bye^6 days, allow us to look for correlations between the simultaneous ultraviolet（UV） emission（from th Optical Monitor） with not only the X-ray flux but also with different X-ray spectral parameters. The X-ray spectra from all the observations are found to be adequately fitted by a double comptonization model where the soft excess and the hard X-ray power law are represented by thermal comptonization in a low temperature plasma and hot corona, respectively. Apart from the fluxes of each component, the hard X-ray power law index is found to be variable. These results suggest that the variability is associated with changes in the geometry of the inner region. The UV emission is found to be variable and well correlated with the high energy index while the correlations with the fluxes of each component are found to be weaker. Using viscous timescale arguments we rule out the possibility that the UV variation is due to the fluctuating accretion rate in the outer disk. If the UV variation is driven by X-ray reprocessing, then our results indicate that the strength of the X-ray reprocessing depends more on the geometry of the X-ray producing inner region rather than on the X-ray luminosity alone.

关键词： galaxies active galaxies Seyfert galaxies individual(Ark 564) X-rays galaxies

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

Potential of conservation tillage and altered land configuration to improve soil properties,carbon sequestration and productivity of maize based cropping system in eastern Himalayas,India

引用

International Soil and Water conservation Research 2021年第2期9卷 279-290页

作者： gulab Singh Yadav Anup Das Subhash Babu Kamal Prasad Mohapatra Rattan Lal Dipjyoti Rajkhowa Indian council of Agricultural Research(IcAR) Research Complex for North Eastern HillRegionTripura CentreTripuraIndia IcAR eIndian Agricultural Research Institute New DelhiIndia IcAR-National Bureau of Plant Genetic Resources New DelhiIndia carbon Management and Sequestration center Ohio State UniversityColumbusUSA IcAR Research complex for NEH Region Nagaland CentreNagalandIndia

Poor soil properties especially low soil organic carbon(SOc)and nutrient and water retention capacities are major concern for sustainable agriculture in *** experiments were conducted to assess the effects of six combinations of tillage[conventional tillage(cT)and no-till(NT)]and land configurations[flat bed planting(FB),ridge and furrow planting(RF),and raised bed planting(RB)]on productivity and carbon(c)-sequestration potential of maize[(Zea mays L.)for green-cob in summer]-maize(for grains in rainy season)-field pea[(Pisum sativum *** winter]cropping system under humid mildtropical climate of Tripura,*** maize under NT-FB in 2012 and NT-RF in 2013 produced significantly higher green cob yield than that under ***,in rainy season,cT produced higher maize grain yield than NT *** pea seed yield was significantly the highest under *** two cropping cycles,NT systems had higher available N,P,K and 18.6e31.4%higher soil moisture content after rainy season maize than cT *** highest SOc-stock(0e30 cm)was observed under NT-FB,whereas,SOc-sequestration rate was maximum under NT-RB(0.85 Mg ha1 year1).Therefore,NT based systems can enhance the productivity and improve SOc-sequestration in cultivated soils of eastern ***,study recommended adoption of NT-RB/NT-FB to raise maize-maize-field pea system for improving productivity,improving c-sequestration and soil properties in the eastern Himalayas and similar eco-regions elsewhere.

关键词： Soil fertility carbon sequestration Soil moisture Low productivity Hill ecosystem

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

crop productivity,soil health,and energy dynamics of Indian Himalayan intensified organic maize-based systems

引用

International Soil and Water conservation Research 2021年第2期9卷 260-270页

作者： Raghavendra Singh Subhash Babu R.K.Avasthe gulab Singh Yadav Anup Das K.P.Mohapatra Amit Kumar Vinod K.Singh Puran chandra IcAR-National Organic Farming Research Institute GangtokSikkim737102India Division of Agronomy ICAR-Indian Agricultural Research InstituteNew Delhi110012India IcAR Research complex for NEH Region Tripura CentreLembucherraTripura799210India IcAR-National Bureau of Plant Genetic Resources New Delhi110012India

The sustainability of prevailing maize-fallow system in rainfed ecosystems of the Eastern Himalayan region(EHR)of India is often questioned due to poor economic return and negative impact on soil ***,the six cropping systems,maize-fallow(M-F),maize t cowpea-rapeseed(M t c-Rs),maize t cowpea-buckwheat(M t c-Bw),maize t cowpea-barley(M t ceB),maize t cowpea-garden pea(M t c-GP)and maize t cowpeaerajmash(M t c-R)in the main plot and three soil moisture conservation measures,no-mulch(NM),maize stover mulch(MSM)and maize stover t weed biomass mulch(MSM t WBM)in sub-plot were evaluated for four consecutive years(2014-18)at a Research Farm in fixed plot *** indicated that cowpea co-culture with maize and inclusion of winter crop increased maize yield by 6.2e23.5%over *** the systems,the M t c-GP recorded the highest crop *** residual effect of MSM t WBM increased maize grain yield by 19.1%over *** of maize t cowpea-winter crops significantly improved the available N(3.2e12.9%),P(3.6 e12.7%),K(1.9e26.3%),organic carbon(9.2e16.8%),microbial biomass carbon-MBc(15.2e43.9%)and dehydrogenases-DHA(17.2e42.3%)in soil at 0e15 cm depth as compared to *** M t c-GP also recorded maximum net return(US$2460 ha1),benefit:cost(B:c)ratio(2.86)and energy use efficiency(7.9%).The MSM t WBM recorded higher net return(US$1680 ha1)and B:c ratio(2.46)over ***,cowpea t maize-garden pea(M t c-GP)along with the application of MSM t WBM is a sustainable production practice to intensify the organically managed maize-fallow system in rainfed regions of the EHR of India and other similar ecosystems.

关键词： crop intensification Energy productivity Gross return Soil health Water productivity

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

Petrogenesis and Tectonic Significance of An Early Paleoproterozoic High-Mg Boninite-Norite-Diorite Suite of Rocks from the Bastar craton, central India

引用

Acta Geologica Sinica(English Edition) 2016年第S1期90卷 116-页

作者： Rajesh K.Srivastava gulab c.Gautam centre of Advanced Study in Geology Banaras Hindu University Department of Applied Geology Dr.Harisingh Gour Central University

Mafic/ultramafic rocks derived from high siliceous(high-Si)high magnesium(high-Mg)mantle melts are an important feature observed during early *** provide much important geological and petrological

关键词： high Si Petrogenesis and Tectonic Significance of An Early Paleoproterozoic High-Mg Boninite-Norite-Diorite Suite of Rocks from the Bastar craton central India

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

巴基斯坦原发性耐多药结核病流行情况

引用

国际结核病与肺部疾病杂志 2008年第2期3卷 73-77页

作者： A.Javaid R.Hasan A.Zafar A.Ghafoor A.J.Pathan A.Rab A.Sadiq c.M.Akram I.Burki K.Shah M.Ansari N.Rizvi S.U.Khan S.R.Awan Z.A.Syed Z.H.lqbal Z.Shaheen N.ur Rehman 邢超 Department of Pulmonology Postgraduate Medical InstituteLady Reading Hospital Peshawar Department of Microbiology Agha Khan University HospitalKarachi TB control Programme North West Frontier Province(NWFP)Peshawar Institute of chest Diseases Kotri Department of Pulmonology Ayub Teaching HospitalAbbotabad Oiha Institute of chest Diseases Karachi gulab Devi Hospital Lahore Lyari General Hospital Karachi National TB control Programme Islamabad Liaqat National Hospital Karachi Jinnah Postgraduate Medical centre Karachi King Edwards Medical University Lahore Nishtar Medical college Multan Allama Iqbal Medical Lahore Wyeth(Pvt) Limited KarachiPakistan

背景:巴基斯坦是世界第6位结核病高负担国家。据世界卫生组织(WHO)估计,巴基斯坦结核病发病率为181/10万,全国每年新增结核病患者28.6万例。来自于医院的资料表明:巴基斯坦耐多药结核病(MDR-TB)问题已十分严重,急需在社区水平对耐多药... 详细信息

背景:巴基斯坦是世界第6位结核病高负担国家。据世界卫生组织(WHO)估计,巴基斯坦结核病发病率为181/10万,全国每年新增结核病患者28.6万例。来自于医院的资料表明:巴基斯坦耐多药结核病(MDR-TB)问题已十分严重,急需在社区水平对耐多药结核病的严重程度开展评估。本研究为针对巴基斯坦耐药结核病流行状况开展的横段面研究,所使用的痰标本来自于巴基斯坦全国742例未经治疗的新诊断的肺结核患者。目的:评估巴基斯坦原发性耐药的流行情况结果:在672例痰培养阳性患者中,有76例(11.3%)出现了对1种或多种抗结核药物耐药。36例(5.4%)患者对链霉素(10μg/ml)耐药; 51例(7.6%)患者对异烟肼(1μg/ml)耐药;15例(2.2%)患者对利福平(5μg/ml)耐药;12例(1.8%)患者对乙胺丁醇(10μg/ml)耐药;22例(3.3%)患者对吡嗪酰胺耐药。有46例(6.8%)患者痰标本中分离的结核菌株耐1种抗结核药物, 10例(1.5%)同时耐2种抗结核药物,12例(1.8%)同时耐3种抗结核药物,6例(0.9%)同时耐4种抗结核药物,2例(0.3%)同时耐全部5种抗结核一线药。原发性耐多药率为1.8%,(n= 12)(异烟肼1μg/ml,利福平5μg/ml)。结论:研究结果表明,巴基斯坦原发性耐多药率<2%,需要进一步实施有效的DOTS策略。

关键词：原发性耐药耐多药结核病巴基斯坦

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

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

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

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：