检索结果-南通市图书馆

Chronic administration of sildenafil improves erectile function in a rat model of chronic renal failure

Asian Journal of Andrology 2015年第5期17卷 797-801,I0008-I0009页

作者： Nilgun Gurbuz arif kol Tumay Ipekci Erhan Ates Asli Baykal Mustafa F Usta Department of Biochemistry Akdeniz University School of Medicine Antalya Turkey Department of Urology Section of Andrology Akdeniz University School of Medicine Antalya Turkey

The relationship between erectile dysfunction （ED） and chronic renal failure （CRF） has been reported in several studies. This study aimed to investigate whether the chronic use of sildenafil could enhance the erectile capacity in CRF-induced rats. In addition, we assessed the effect of that treatment on certain molecules, which have been suggested to play crucial roles in erectile physiology and CRF-related ED as well. Three groups of animals were utilized：（1） age-matched control rats, （2） CRF-induced rats, （3） CRF-induced rats treated with chronic administration of sildenafil （5 mg kg^-1 p.o. for 6 weeks [treatment started after 6 weeks of CRF induction]）. At 3 months, all animals underwent cavernosal nerve stimulation （CNS） to assess erectile function. Penile tissue advanced glycation end products （AGE＇s）/5-hydroxymethyl-2-furaldehyde, malondialdehyde （MDA）, cGMP （ELISA）, inducible nitric oxide synthase （iNOS） and neuronal NOS （nNOS）（Western blot） analyses were performed in all rat groups. CRF-induced rats had a significant decrease in erectile function when compared to control rats （P 〈 0.05）. The increase in both intracavernosal pressure （ICP） and area under the curve of CRF-induced rats treated with sildenafil （Group 3） was greater than CRF-induced rats （Group 2）. Additionally, sildenafil treatment decreased AGE, MDA and iNOS levels, while it preserved nNOS and cGMP contents in CRF-induced penile tissue. Decreased AGE, MDA, iNOS and increased nNOS, cGMP levels at the sildenafil-treated group increased both ICP and Total ICP to CNS, which led to improve erectile function in CRF-induced rats. The results of the present study revealed the therapeutic effect of chronic sildenafil administration on erectile function in CRF-induced rats.

关键词： chronic renal failure erectile function sildenafil

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

Local symmetries of finite type hypersurfaces in C^2 Dedicated to Professor Sheng GONG on the occasion of his 75th birthday

引用

Science China Mathematics 2006年第11期49卷 1633-1641页

作者： kol■ Martin Depart. of Mathematical Analysis Masaryk University Janackovo Nam. 2A662 95 BrnoCzech Republic

The first part of this paper gives a complete description of local automorphism groups for Levi degenerate hypersurfaces of finite type in C2. It is also proved that, with the exception of hypersurfaces of the form v = |z|k, local automorphisms are always determined by their 1-jets. Using this result, the second part describes special normal forms which by an additional normalization eliminate the nonlinear symmetries of the model and allows to decide effectively about local equivalence of two hypersurfaces given in this normal form.

关键词： normal form finite type hypersurfaces local equivalence problem finite jet determination stability group.

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 procedural footprint enhancement of global topographic surface with multiple levels of detail

引用

International Journal of Digital Earth 2020年第4期13卷 527-545页

作者： Lukáš Brůha Jan kolář Faculty of Science Department of Applied Geoinformatics and CartographyCharles University in PraguePragueCzech Republic Grifinor Project CopenhagenDenmark

Virtual globes are technologies for visual navigation through a threedimensional,multi-resolution model of the entire *** representations used in virtual globes,however,lack geometric flexibility at high-resolution levels of the planet-wide terrain *** is a problem especially if boundaries between individual geospatial features and the terrain are important.A novel integration of individual polygonal boundaries with a specific multi-resolution representation of the planet-wide terrain is developed in this *** the preparation stage,the integration relies on an original simplification algorithm applied to the polygonal boundaries between geospatial features and the *** output is a multiple level-of-detail(LOD)geometry,which can be combined with a known multi-LOD representation of the terrain that uses run-time *** data representation is suitable for storage in existing database systems,avoids any data redundancy across LODs,and is even independent of the subdivision schema that partitions the planet’s surface for the sake of dealing with *** runtime,a novel reconstruction algorithm stitches geometric parts from different LODs together in a manner that augments the multi-LOD representation of the *** a certain proximity range from a given position,the method reconstructs a scene that preserves topological relations between the boundaries of geospatial features with the *** method also guarantees that certain nearest proximity to the given position consists of the best geometries that correspond to the original *** properties of the method close up the gap between a mere exploratory visualization of static,pre-generated models and the models supporting geospatial analysis,which is deemed crucial for applications in Geographic Information Systems,Building Information Modelling and other software industries.A prototype implementation and experiment results that prove this method are also prese

关键词： Feature-based topography multiple level-of-detail procedural modeling vector data organization geometry reconstruction

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

科教协同、小组化讨论在基础医学教学中的运用

引用

基础医学教育 2024年 901-905页

作者：郑莉灵周龙张汕 kol Jia Yong 于淼诗音李笑雨王国珍周以侹浙江大学基础医学院生物化学系浙江大学基础医学院生物物理学系

基础医学是医学院的一门重要基础学科。目前不少高校师资老化,基础医学教科书更新不够快,教学方式仍是传统“填鸭式”的灌输教学,缺乏科研思维能力的培养和思政教育。针对这些不足,浙江大学基础医学院引入优质青年师资,提倡以科研反哺教... 详细信息

基础医学是医学院的一门重要基础学科。目前不少高校师资老化,基础医学教科书更新不够快,教学方式仍是传统“填鸭式”的灌输教学,缺乏科研思维能力的培养和思政教育。针对这些不足,浙江大学基础医学院引入优质青年师资,提倡以科研反哺教学,开展小组讨论的教学模式,通过最新文献补充教材,由浅入深引导学生了解最新的科研进展,逐步培养学生的科研思维能力。这种科教协同与小组化讨论模式在基础医学教育中的融合运用将有助于提高教育质量,培养适应现代化科学发展的高素质医学生。

关键词：基础医学科教协同小组化讨论生物化学与分子生物学综合能力

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Diversity of foliar endophytes in wind-fallen Picea abies trees

引用

Fungal Diversity 2012年第3期54卷 69-77页

作者： Ondřej Koukol Miroslav kolařík Zuzana kolářová Petr Baldrian Department of Botany Faculty of ScienceCharles University in PragueBenátská212801 Prague 2Czech Republic Laboratory of Genetics Physiology and Bioengineering of FungiInstitute of Microbiology of the ASCRv.v.i.Vídeňská108314220 Prague 4Czech Republic Laboratory of Environmental Microbiology Institute of Microbiology of the ASCRv.v.i.Vídeňská108314220 Prague 4Czech Republic

The unmanaged Norway spruce montane forests in the Bohemian Forest National Park(Czech Republic)suffered from repeated large-scale bark beetle outbreaks in last *** this study,the diversity of culturable foliar endophyte microfungi in needles originating from eleven recently wind-fallen trees in this area was *** aims were to describe their diversity and to determine the relative host and organ specificities of isolated endophyte species to estimate the species pool and abundance of foliar endophytes before the forest *** were isolated from surface-sterilized needles,and the outgrowing strains were identified based on morphological and molecular characteristics(analyses of ITS1,ITS2 and partial 28S rDNA).Fungal communities in the needles were diverse,with ascomycetes(mostly anamorphs of Helotiales)dominating *** most frequent species(Phacidiopycnis sp.,Cistella acuum,Sirococcus *** two species of Chalara)did not correspond with those recorded in previous studies of Picea *** example,the widely distributed Lophodermium piceae was rarely recorded in this *** pattern may be caused by different methods of sterilization and cultivation or by physiological characteristics of the needles,or it may reflect the species distribution in the studied *** of the Helotiales,along with sequences from GenBank,showed substantial overlap in host affinities,most prominently between Pinus and Picea,and also among species from distant plant lineages.

关键词： Morphospecies ITS rDNA Culturable microfungi Phacidiopycnis Host affinity

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

澜湄开放教育及柬埔寨远程教育的未来

引用

云南开放大学学报 2024年第1期26卷 10-19页

作者：春昌丹科尔·森哈克沃克·索万纳罗特 IIC University of Technology Phnom Penh Cambodia

This journal article delves into the future of distance learning in Cambodia and the potential for collaboration with the Mekong-Lancang Open Education initiative. It explores how distance learning can successfully address the current issues the Cambodian educational system is currently facing. The article discusses the goals and opportunities for collaboration that the Mekong-Lancang Open Education initiative presents, as well as the difficulties and potential solutions involved in implementing distance learning in Cambodia. Moreover,the article also offers insightful case studies and best practices from other countries, offering valuable insights and lessons for Cambodia. Lastly, the article concludes with policy recommendations for the future of distance learning in Cambodia. Future research and studies should concentrate on continually evaluating and improving the Mekong-Lancang Open Education Initiative to ensure that it effectively meets the educational needs of students and educators.

关键词： Distance Learning Mekong-Lancang Open Education Education Challenges Collaboration Policy Recommendations

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

Security Analysis of IEEE802.11i in Wireless Local Area Network

Security Analysis of IEEE802.11i in Wireless Local Area Netw...

引用

作者： kol Phanna 中南大学

学位级别：硕士

随着无线局域网（WLAN）的不断普及,企业和教育机构越来越关注无线网络的安全问题。无线网络的安全非常重要,因为安全的网络不仅可以阻止计算机访问未经授权的网页,还能避免给计算机带来损害。随着服务变得越来越流行,无线技术也得到了... 详细信息

随着无线局域网（WLAN）的不断普及,企业和教育机构越来越关注无线网络的安全问题。无线网络的安全非常重要,因为安全的网络不仅可以阻止计算机访问未经授权的网页,还能避免给计算机带来损害。随着服务变得越来越流行,无线技术也得到了改进,因此,安全成了人们必须重视的首要问题。 IEEE802.1X安全协议作为第一个无线网络通信标准,一直被广泛使用。但是该标准却存在数据的机密性与安全性问题。而最新的WLAN安全协议标准IEEE802.11i-2004（802.11i）则解决了这些问题,IEEE802.11i严格确保了无线局域网络的安全性。无线网络通信标准802.11i安全协议确保无线网络的安全。论文首先介绍了无线网络通信标准IEEE802.11以及该标准存在有问题,然后课题着重研究了IEEE802.11i无线安全,相比于IEEE802.11它涉及到许多改进：提升加密算法AES的性能、完善密钥的管理。IEEE802.11i作为IEEE802.11的一个修定标准,更好地加强了无线局域网的安全性。802.11i通过使用临时密钥完整性协议（TKIP）提高有线等效密码（WEP）的安全性。在820.11i标准中,WLAN使用的有线等效密码（WEP）技术被WPA2取代,WPA2使用的是更高级的加密标准（AES-CCMP）新技术。本研究课题接着分析了在强健安全网络（RSN）方面,IEEE802.11i的优势,它取代了之前的强健安全网络（PreRNS）,提供了新的安全保障,尤其是数据的保密性和完整性。Rijndael提出的AES可以阻止计算机进入未经允许访问的网络,也就是在CCMP的AES加密模式下可以防止黑客侵入。同时,它还设法减少如今网络存在的大量威胁,这些威胁曾一直给使用无线网络的公司带来不可预测的风险。但是,AES算法的密码长度只有128位,论文针对这一问题,讨论了不同于Rijndael的AES算法的一种新的密码算法,相比于Rijndael在AES算法中使用的128位密码长度,新算法使用200位的密码长度,与之进行对比新算法明显提高了密码的安全性能。

关键词： Counter-mode/CBC-MAC协议临时密钥完整性协议高级加密标准 Rijndael算法

来源：

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Analysis of Geometrical Parameters of Tubular TY-Joints on Stress Concentration Factors Due to Axial Loads

引用

Journal of Marine Science and Application 2022年第2期21卷 133-143页

作者： Mohamadou Aminou Sambo Guy Richard kol Gambo Betchewe Faculty of Sciences University of MarouaMaroua P.O.Box 46Cameroon National Advance School of Mines and Petroleum Industries University of MarouaMaroua P.O.Box 46Cameroon School of Geology and Mining Engineering University of NgaoundéréNgaoundéréP.O.Box 454Cameroon

In this paper,the influence of geometric parameters on the stress concentration factors due to three different types of axial loading on 81 TY tubular structures is *** results reveal that,geometric parameters have a considerable impact on the variation of stress concentration factors on tubular TY-joints under axial ***,the highest stress concentration factor values are observed on the vertical brace than on the inclined *** finite element results of the tubular structures were verified by parametric equations and experimental data.A parametric study was carried out by analyses using the nonlinear regression method to obtain parametric *** equations are used to calculate stress concentration factors and to analyse the fatigue resistance of TY-joints due to axial loads.

关键词： Offshore structure Tubular TY-joint Stress Concentration Factor Fatigue Axial load

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

Analysis of Stress Concentration Factors due to in-Plane Bending and out-of-Plane Bending Loads on Tubular TY-Joints of Offshore Structures

引用

Journal of Marine Science and Application 2022年第4期21卷 78-94页

The aim of this work is to study the stress distributions and the location of hot spots stress in the vicinity of the intersection lines of the tubular elements of the tubular *** the finite element models,we analyze the effects of geometrical parameters on the stress concentration factor in the case of in-plane bending and out-of-plane bending loads,around the weld toe of the tubular *** results reveal the location of the maximum stress concentration factor at the heel or toe in the case of in-plane bending loads and at the saddle point in the case of out-of-plane bending *** parametric equations are established and used to calculate the stress concentration factor at critical locations using the non-linear regression *** results obtained from the finite element analysis are close to the results of the parametric equations and the experimental data from the previous work.

关键词： Offshore platform Tubular TY-joint Stress concentrations Fatigue In-plane bending Out-of-plane bending

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

褪黑素合成酶基因转化烟草及转化植株抗氧化系统变化

引用

生物工程学报 2009年第7期25卷 1014-1021页

作者：王英娟贾敬芬步怀宇赵宇玮许耀 Carl Hirschie Johnson Jan kolár 西北大学生命科学学院陕西省生物技术重点实验室西安710069 Department of Biology Box1812-BVanderbilt University Institute of Experimental Botany Academy of Sciences of the Czech Republic

通过根癌农杆菌(含植物表达载体YXu55)介导的转化技术,将褪黑素生物合成酶-芳烷基胺N-乙酰转移酶(Arylalkylamine N-acetyltransferase,AANAT)与羟基吲哚O-甲基转移酶(Hydroxyindole O-methyltransferase,HIOMT)基因导入到烟草(秦烟95)中。对所获得的庆大霉素抗性烟草株系进行Southern blotting和RT-PCR分子生物学检测,结果表明,AANAT-HIOMT基因已成功地整合到烟草基因组中,并且可以在mRNA水平上进行转录。用反相高效液相色谱法(RP-HPLC)测定转化株系的褪黑素含量表明,转AANAT-HIOMT基因烟草株系的褪黑素含量均明显高于pZP122(不含AANAT和HIOMT基因的空白质粒)转基因株系和未转基因的对照植株,证明AANAT-HIOMT基因在转基因植株中的表达增强了褪黑素的合成能力。对不同株系抗氧化系统的部分指标进行了测定,并与其亲本对照植株比较,发现AANAT-HIOMT基因在转基因植物中的表达引起超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性增加,谷胱甘肽(GSH)浓度以及总抗氧化能力升高,且没有引起膜脂质过氧化物丙二醛(MDA)的变化,说明转基因烟草抗氧化潜能得到提高。

关键词：烟草褪黑素褪黑素合成酶基因遗传转化抗氧化

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

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：