检索结果-南通市图书馆

Web search and data mining of natural products and their bioactivities in PubChem

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

Science China Chemistry 2013年第10期56卷 1424-1435页

作者： hAO Ming ChENG Tiejun WANG Yanli BRYANT h. stephen National Center for Biotechnology Information National Library of Medicine National Institutes of HealthBethesda MD 20894 USA

Natural products,as major resources for drug discovery historically,are gaining more attentions recently due to the advancement in genomic sequencing and other technologies,which makes them attractive and amenable to drug candidate *** and mining the bioactivity information of natural products are extremely important for accelerating drug development process by reducing ***,a number of publicly accessible databases have been established to facilitate the access to the chemical biology data for small molecules including natural ***,it is imperative for scientists in related fields to exploit these resources in order to expedite their researches on natural products as drug leads/candidates for disease ***,as a public database,contains large amounts of natural products associated with bioactivity *** this review,we introduce the information system provided at PubChem,and systematically describe the applications for a set of PubChem web services for rapid data retrieval,analysis,and downloading of natural *** hope this work can serve as a starting point for the researchers to perform data mining on natural products using PubChem.

关键词： natural products drug discovery PubChem public database data mining

Enemy release at range edges:do invasive species escape their herbivores as they expand into new areas?

在线全文

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2016年第5期9卷 636-647页

作者： Justin S.h.Wan stephen P.Bonser Evolution and Ecology Research Centre School of BiologicalEarth and Environmental SciencesUNSW AustraliaSydneyNew South Wales 2052Australia

Aims We test the hypothesis that invasive plant species at their range edges experience lower herbivory and allocate less to defense at the edge of an expanding range edge than from more central parts of their distribution,during secondary invasion in a new *** plants are often able to spread rapidly through new *** success of invasive species in new ranges is frequently attributed to enemy release in these new areas and associated evolutionary changes minimizing allocation to defense in favor of growth and *** release could also explain rapid advances of invasive species upon arriving in new *** invasive species accumulate enemies over time in a new location,then these species may experience a release from their enemies at expanding range *** release at these range fronts may accelerate range *** We used populations of four woody invasive species within the invaded range,and four native control *** quantified leaf herbivory and leaf physical defense traits at both range central and range edge locations,over two 1-month sampling periods,sampled 7 months *** Findings herbivory at the range edge did not differ to the range center but patterns were not consistent across *** was a trend for lower herbivory at the range edge for Lantana camara,which was reflected in lower leaf ***,leaf toughness was greater at the range edge location across invasive and control *** defenses were different among range locations in a few species,though most species show the same trend,suggesting higher herbivory pressures at the range edge location or differences may be due to climatic *** of *** were significantly less tough at range edges,suggesting that some species can potentially escape their enemies at range ***,our results overall do not support the hypothesis that plants at the edge of their ranges experience reduced impact from their enem

关键词： Australian woodlands enemy release hypothesis herbivory invasion dynamics physical defense range edge

Autosub6000:A Deep Diving Long Range AUV

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

Journal of Bionic Engineering 2009年第1期6卷 55-62页

作者： stephen McPhail Underwater Systems Laboratory National Marine Facilities DivisionNational Oceanography CentreSouthampton SO14 3ZHUK

With an ultimate range up to 1000 km,a maximum operating depth of 6000 m,and a generous payload capacity,Autosub6000 is well placed to become one of the world's most capable deep diving Autonomous Underwater Vehicles(AUVs). Recently,Autosub6000 successfully completed its first deep water engineering trials,and in September 2008,fitted with a multibeam sonar,will carry out its first science *** paper will describe how we are tackling the design issues that specifically affect a deep diving AUV which must be capable of operating with true autonomy,independently of the mother ship, namely:carrying adequate energy for long endurance and range,coping with varying buoyancy,and maintaining accurate navigation throughout missions lasting up to several *** from the recent engineering trails are presented,and future missions and development plans are discussed.

关键词： AUV robotics navigation lithium polymer battery deep ocean research

Generalized Parallel Signature Analyzers with External Exclusive-OR Gates

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 1986年第4期1卷 49-61页

作者：沈理 stephen Y.h.Su Institute of Computing Technology Academia Sinica Beijing Watson School State University of New York Binghamton NY 13901

A new generalized parallel signature analyzer with external Exclusive-OR gates(GPSA-EE)*** allows the signature analyzer to have twice the number of inputs compared with an originalparallel signature *** equivalence between a GPSA-EE and an SSA-EE(serial signatureanalyzer)is *** the concept of multiple signatures,the error detection capability of signatureanalyzer can be enhanced by changing the connection between signature analyzer and circuit-under-test,or changing the characteristic polynomial p(x)of signature analyzer.

关键词： Generalized Parallel Signature Analyzers with External Exclusive-OR Gates LFSR IE PSA EE 丹一

Manipulation of the intestinal microbiome-a slow journey to primetime

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2023年第21期11卷 4975-4988页

作者： Ofra Kriger-Sharabi stephen D h Malnick David Fisher Institute of Gastroenterology Assuta Medical CenterAshdod 7747629Israel Department of Internal Medicine Kaplan Medical CenterRehovot 76100Israel Department of Endocrinology Soroka Medical CenterBeer Sheva POB 151Israel

The gut microbiota has important functions in the regulation of normal body *** of the microbiota are being increasingly linked to various disease *** microbiome has been manipulated via the administration of stool from animals or humans,for more than 1000 ***,fecal microbiota transplantation can be performed via endoscopic administration of fecal matter to the duodenum or colon or via capsules of lyophilized *** recently fecal microbial transplantation has been shown to be very effective for recurrent Clostridoides difficile infection(CDI).In addition there is some evidence of efficacy in the metabolic syndrome and its hepatic manifestation,metabolic associated fatty liver disease(MAFLD),irritable bowel syndrome(IBS)and inflammatory bowel disease(IBD).We review the current literature regarding the microbiome and the pathogenesis and treatment of CDI,MAFLD,IBS and IBD.

关键词： Gut microbiota Fecal microbiota transplantation Clostridoides difficile Metabolic associated fatty liver disease Irritable bowel syndrome Inflammatory bowel disease

Palaeogeographic variation in the Permian-Triassic boundary microbialites:A discussion of microbial and ocean process esafter the end-Permian mass extinction

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

Journal of Palaeogeography 2017年第2期6卷 97-107页

作者： stephen Kershaw Department of Life Sciences Brunel University Kingston Lane Uxbridge UB8 3PH UK

Shallow marine carbonate sediments that formed after the end-Permian mass extinction are rich in a thin(maximum ca.15 m) deposit of *** communities that constructed the microbialites have geographic variability of composition,broadly divisible into two groups:1) eastern Tethys sites are calcimicrobe-dominated(appearing as thrombolites in the field),with rare occurrence of sedimentconstructed microbialites and uncommon cements either within microbial structure or as inorganic precipitates,2) other Tethys sites are sediment-dominated structures forming stromatolites and thrombolites,composed of micrites and cements,with some inorganic *** other Tethys locations include western and central Tethys sites but their palaeogeographic positions depend on the accuracy of continental reconstructions,of which there are several *** contrast to geographic variation of microbialites,the conodont hindeodus parvus,which appeared after the extinction and defines the base of the Triassic,is widespread,indicating easy lateral migration throughout *** animals were active nekton,although being small animals were presumably at least partly carried by water currents,implying active Tethyan surface water circulation after the extinction ***-extinction ammonoid taxa,presumed active swimmers,show poor evidence of a wide distribution in the Griesbachian beds immediately after the extinction,but are more cosmopolitan higher up,in the Dienerian strata in *** shelly fossils also have poorly defined distributions after the extinction,but ostracods show some wider distribution suggesting migration was possible after the *** there is a contrast between the geographic differences of microbialites and some shelly *** the cause of geographic variation of post-extinction microbialites is problematic and may include one or more of the following possibilities:1) because calcifying microbial organisms th

关键词： Stromatolite Thrombolite Microbialite Permian-Triassic boundary Conodonts Tethys Mass extinction

Free vibration and transient response of double curved beams connected by intermediate straight beams

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 37-62页

作者： R.A.JAFARI-TALOOKOLAEI h.GhANDVAR E.JUMAEV S.KhATIR T.CUONG-LE School of Mechanical Engineering Babol Noshirvani University of Technology Department of Mechanical Engineering Faculty of Engineering New Uzbekistan University University of Business and Science Center for Engineering Application and Technology Solutions Ho Chi Minh City Open University

This paper investigates the free vibration and transient response of interconnected structures including double curved beams and intermediate straight beams,which are all constructed from functionally graded porous(FGP) materials. The strain potential and kinetic energies of each beam along with the work done by the external force are calculated. Additionally, a higher-order beam element is introduced to derive stiffness and mass matrices, along with the force vector. The curved and straight beams are discretized, and their assembled stiffness, mass matrices, and force vectors, are *** conditions at the joints are used to derive the total matrices of the entire structure. Subsequently, the natural frequencies and transient response of the system are determined. The accuracy of the mathematical model and the self-developed computer program is validated through the comparison of the obtained results with those of the existing literature and commercial software ANSYS, demonstrating excellent ***, a comprehensive study is conducted to investigate the effects of various parameters on the free vibration and transient response of the considered structure.

关键词：

Soil hydraulic Properties： Influence of Tillage and Cover Crops

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2018年第3期28卷 430-442页

作者： Samuel I. hARUNA stephen h. ANDERSON Nsalambi V. NKONGOLO Syaharudin ZAIBON School of Agriculture College of Basic and Applied Sciences Middle Tennessee State University 1301 East Main Street Murfreesboro TN 37132-0001( USA) Department of Soil Environmental and Atmospheric Sciences 302 Anheuser-Busch Natural Resources Building University of Mis-souri Columbia MO 65211-0001( USA) Institut Facultaire des Sciences Agronomiques (IFA-Yangambi) Boite Postale Kisangani 1232( Democratic Republic of Congo) Department of Land Management Faculty of Agriculture University Putra Malaysia 43400 Serdang Selangor Malaysia

Understanding the effects of cover crops and tillage on soil physical properties is important for determining soil productivity. This study was conducted at Lincoln University＇s Freeman Center, USA to evaluate the effects of tillage and cover crop management on soil hydraulic properties. The field site included three replicate blocks in a randomized complete block design with each plot measuring 21.3 m in length and 12.2 m in width. Treatment factors were tillage at two levels （moldboard plow tillage vs. no tillage） and cover crop at two levels （cereal rye （Secale cereal） cover crop vs. no cover crop）. Soil samples were collected in late spring/early summer from each treatment at 10-cm depth increments from the soil surface to a depth of 40 cm using cores （76.2-mm diameter and 76.2-mm length）. Soil bulk density was 13% lower with tillage compared with no-tillage. Volumetric water content was significantly higher at 0.0 and -0.4 kPa pressures with tillage compared with no tillage. Tillage increased the proportion of coarse mesopores by 32gc compared with no tillage, resulting in 87% higher saturated hydraulic conductivity （Ksat）. Cover crop increased the proportion of macropores by 24~ compared with no cover crop; this can potentially increase water infiltration and reduce runoff. As a result of higher macroporosity, Ksat was higher under cover crop compared with no cover crop. This study demonstrated that tillage can benefit soil hydraulic properties in the short term, but these effects may not persist over time. Cover crops may slightly improve soil hydraulic properties, but longer term studies are needed to evaluate the long-term effects.

关键词： pore size distribution saturated hydraulic conductivity soil bulk density soil water retention volumetric water content

Combining Aluminum heat Treat with hot Isostatic Pressing: A Comparison of Structure, Properties, and Processing Routes for a Cast AI-Si-Mg Alloy

在线全文

学校读者我要写书评

暂无评论

材料热处理学报 2004年第5期25卷 546-551页

作者： stephen J. Mashl Body cote hIP Inc. Andover Massachusetts USA

Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal?, a proprietary, aluminum specific, hot isostatic pressing (hIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response from that seen in conventional processing. This paper reviews the results of experiments performed to Al-Si-Mg (A356.0) castings subjected to both combined and conventional processing routes. Results indicate that the combined hIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.

关键词： Al-Si-Mg合金热处理热等静压缩 hIP 机械性质疲劳寿命