期刊文献+
共找到37,874篇文章
< 1 2 250 >
每页显示 20 50 100
KaKs_Calculator 2.0:A Toolkit Incorporating Gamma-Series Methods and Sliding Window Strategies 被引量:113
1
作者 Dapeng Wang Yubin Zhang +2 位作者 Zhang Zhang Jiang Zhu Jun Yu 《Genomics, Proteomics & Bioinformatics》 SCIE CAS CSCD 2010年第1期77-80,共4页
We present an integrated stand-alone software package named KaKs_Calculator 2.0 as an updated version. It incorporates 17 methods for the calculation of nonsynonymous and synonymous substitution rates; among them, we ... We present an integrated stand-alone software package named KaKs_Calculator 2.0 as an updated version. It incorporates 17 methods for the calculation of nonsynonymous and synonymous substitution rates; among them, we added our modified versions of several widely used methods as the gamma series including y-NG, y-LWL, ),-MLWL, y-LPB, y-MLPB, y-YN and y-MYN, which have been demonstrated to perform better under certain conditions than their original forms and are not implemented in the previous version. The package is readily used for the identification of positively selected sites based on a sliding window across the sequences of interests in 5' to 3' direction of protein-coding sequences, and have improved the overall performance on sequence analysis for evolution studies. A toolbox, including C++ and Java source code and executable files on both Windows and Linux platforms together with a user instruction, is downloadable from the website for academic purpose at https://sourceforge.net/projects/kakscalculator2/. 展开更多
关键词 Ka/Ks gamma-series methods sliding window positively selected sites
原文传递
Correlation and Path Analysis for Growth Traits in F_1 Population of Pearl Oyster Pinctada martensii 被引量:34
2
作者 邓岳文 杜晓东 +2 位作者 王庆恒 符韶 黄荣莲 《Marine Science Bulletin》 CAS 2008年第2期68-73,共6页
120 pearl oysters (Pinctada martensii) were randomly sampled from F1 population, and shell length, shell width, shell height, shell weight and total weight of each sample were measured. Correlation and path analysis... 120 pearl oysters (Pinctada martensii) were randomly sampled from F1 population, and shell length, shell width, shell height, shell weight and total weight of each sample were measured. Correlation and path analysis were conducted on the basis of measurement data. The results showed that shell length, shell width, shell height, shell weight and total weight were significantly correlated (P 〈 0.05). Total weight was significantly and positively correlated with shell weight (r = 0.8970), shell height (r = 0.6974), shell width (r = 0.6521) and shell length (r = 0.5486). Shell weight, shell height, shell width and shell length had positive and direct effects on total wet weight, with the values of 0.6356, 0.1872, 0.1814 and 0.0599, respectively. The results indicated that growth traits (shell length, shell width, shell height, shell weight and total wet weigh) of the F1 population could be improved by direct or indirect selection. 展开更多
关键词 Pinctada martensii selected line F1 growth traits CORRELATION path analysis
下载PDF
Tales of the Tail and Sperm Head Aches --Changing concepts on the prognostic significance of sperm pathologies affecting the head, neck and tail 被引量:17
3
作者 Hector E Chemes Cristian Alvarez Sedo 《Asian Journal of Andrology》 SCIE CAS CSCD 2012年第1期14-23,174,共11页
This article presents an update on the variable prognostic significance of different sperm pathologies in patients with severe male factor infertility due to morphology and motility disorders. Severe asthenozoospermia... This article presents an update on the variable prognostic significance of different sperm pathologies in patients with severe male factor infertility due to morphology and motility disorders. Severe asthenozoospermia is one of the leading causes of male infertility as spermatozoa cannot reach the oocyte and/or penetrate normally. Identifying structural causes of sperm immotility was of great concern before the advent of intracytoplasmic sperm injection (ICSI), because immotility was the limiting factor in the treatment of these patients. In these cases, in vitro methods are used to identify live spermatozoa or stimulate sperm motility to avoid selection of non-viable cells. With these advances, fertilization and pregnancy results have improved dramatically. The identification of genetic phenotypes in asthenozoospermia is important to adequately inform patients of treatment outcomes and risks. The one sperm characteristic that seriously affects fertility prognosis is teratozoospermia, primarily sperm head and neck anomalies. Defects of chromatin condensation and acrosomal hypoplasia are the two most common abnormalities in severe teratozoospermia. The introduction of microscopic methods to select spermatozoa and the development of new ones to evaluate sperm quality before ICSI will assure that ultrastructural identification ofsperm pathologies will not only be of academic interest, but will also be an essential tool to inform treatment choice. Herein, we review the differential roles played by sperm components in normal fertilization and early embryo development and explore how assisted reproductive technologies have modified our concepts on the prognostic significance of sperm pathologies affecting the head, neck, mid-piece and tail. 展开更多
关键词 acrosomal hypoplasia chromatin anomalies fertility prognosis intracytoplasmic sperm injection intracytoplasmic injection of morphologically selected spermatozoa sperm neck defects sperm pathologies tail abnormalities TERATOZOOSPERMIA
下载PDF
35kV电缆设计中三芯与单芯电缆的选择与比较 被引量:18
4
作者 韩立奎 王海涛 韩晓冰 《电线电缆》 2011年第5期15-16,22,共3页
电力电缆的三芯与单芯的选取一般遵循如下规律:6~10 kV电缆选择三芯电缆,66 kV及以上电缆选择单芯电缆。但是35 kV电压等级电缆既有三芯又有单芯,如何正确的选取是广大工程技术人员需要面对的一道难题。通过对35 kV三芯与单芯电缆的分... 电力电缆的三芯与单芯的选取一般遵循如下规律:6~10 kV电缆选择三芯电缆,66 kV及以上电缆选择单芯电缆。但是35 kV电压等级电缆既有三芯又有单芯,如何正确的选取是广大工程技术人员需要面对的一道难题。通过对35 kV三芯与单芯电缆的分析与比较,明确了各自的适用环境与条件,可以为广大电力技术人员在工程实践中选用电缆提供一定的借鉴与帮助。 展开更多
关键词 电缆线路设计 三芯电缆 单芯电缆 比较 选用
下载PDF
凡口铅锌矿尾矿的综合利用 被引量:13
5
作者 曾懋华 龙来寿 +2 位作者 奚长生 彭翠红 方振鹏 《韶关学院学报》 2004年第12期56-59,共4页
通过对凡口铅锌矿尾矿的综合利用现状调查与分析,结合我国当今尾矿回收利用的新技术,提出了一种适合凡口铅锌矿尾矿综合利用的新方法,通过对尾矿中有价金属的再选、对+0.019mm的尾矿进行采空区的充填、将-0.019mm的尾矿用于制地面砖和... 通过对凡口铅锌矿尾矿的综合利用现状调查与分析,结合我国当今尾矿回收利用的新技术,提出了一种适合凡口铅锌矿尾矿综合利用的新方法,通过对尾矿中有价金属的再选、对+0.019mm的尾矿进行采空区的充填、将-0.019mm的尾矿用于制地面砖和水泥熟料,最后采用堆土复垦方法处理,最终可达到无尾矿矿山的目标. 展开更多
关键词 凡口铅锌矿 尾矿 综合利用 尾矿再选 充填
下载PDF
油松种子园无性系花量和生长量调查及其评价 被引量:11
6
作者 秦月明 安守芹 黄荣凤 《内蒙古林学院学报》 1996年第1期9-15,共7页
调查结果表明,油松无性系花量的变异很大。雌花在冠层外围均有分布,以中层较多,雄花主要分布在下层。花量最多的无性系是最少的倍数:雄花为225.8倍,雌花为8.4倍。花量与生长量指标非常密切相关。应用座标法对无性系进行评... 调查结果表明,油松无性系花量的变异很大。雌花在冠层外围均有分布,以中层较多,雄花主要分布在下层。花量最多的无性系是最少的倍数:雄花为225.8倍,雌花为8.4倍。花量与生长量指标非常密切相关。应用座标法对无性系进行评价,选出优良无性系占调查总数的26.7%,雄雌花量分别比平均值超过53.2%和40.5%。这些调查结果为种子园的经营管理提供了依据。 展开更多
关键词 种子园 无性系 花量 选择 油松
下载PDF
基于立体化形式的高校公共体育教材建设研究 被引量:11
7
作者 杨敏 钟利 +1 位作者 武卫 王勇 《体育与科学》 CSSCI 北大核心 2007年第6期90-92,53,共4页
高校公共体育教材建设是提高公共体育教育教学质量的重要环节,而立体化的体育教材又是一种新型的整体教育教学解决方案,是教材建设的一种创新,引领了教材建设的新观念、新思想。本文采用文献资料、专家访谈、分析等研究方法,阐述了立体... 高校公共体育教材建设是提高公共体育教育教学质量的重要环节,而立体化的体育教材又是一种新型的整体教育教学解决方案,是教材建设的一种创新,引领了教材建设的新观念、新思想。本文采用文献资料、专家访谈、分析等研究方法,阐述了立体化教材的涵义和建设的必要性,总结分析了我国高校体育教材建设的现状,提出构建标准化的立体化体育教材选编体系。并从多层次讨论了其建设的内容、实施步骤与思路,在教材撰写的原则、内容和结构上既能体现体育的学科特点,又能实现标准化的目标要求,以推动公共体育教学改革的深入进行,使之成为既有价值的学术创造,又能对高校公共体育领域具有广泛指导意义的新型教材。 展开更多
关键词 公共体育 立体化教材 选编 原则 结构 特点
下载PDF
以柠条为主要基质栽培食用菌的配方筛选研究 被引量:12
8
作者 刘秉儒 宋乃平 +2 位作者 苏建宇 贺永喜 牛瑛萍 《北方园艺》 CAS 北大核心 2012年第24期168-170,共3页
以宁夏荒漠草原的柠条粉碎料为试材,以柠条粉占78%(A)、68%(B)和58%(C)的3种不同培养基为主料,以不添加和添加10%、20%玉米芯配制栽培料,研究了不同培养料配方对平菇、金针菇、黑木耳生物学转化率的影响,以期筛选柠条作为主要基质的适... 以宁夏荒漠草原的柠条粉碎料为试材,以柠条粉占78%(A)、68%(B)和58%(C)的3种不同培养基为主料,以不添加和添加10%、20%玉米芯配制栽培料,研究了不同培养料配方对平菇、金针菇、黑木耳生物学转化率的影响,以期筛选柠条作为主要基质的适宜比例。结果表明:3种蘑菇都能够在以柠条粉为主料的培养基中正常生长并形成子实体,平菇、金针菇、黑木耳的生物学转化率分别达64.9%、62.5%和42.9%,但同种类蘑菇不同配方的生物学转化率有差别,在栽培的3种蘑菇中,生物学转化率由大到小的配方顺序均为C>B>A,而且差异显著;同时,在生物学转化率最高的C配方中,产量高低顺序是:平菇>金针菇>黑木耳。这说明在以柠条为主要基质的栽培料中添加一定比例的玉米芯,可以提高菌种的生长速度,缩短生产周期,提高生物学转化率与产量;在相同的配方中,平菇的生物学转化率显著高于其它蘑菇,因此柠条占58%、玉米芯占20%的C配方可作为最优栽培方案。 展开更多
关键词 柠条粉 食用菌 基质 筛选 生物学转化率
下载PDF
Growth performance and physiological parameters of the second generation selected and control groups of Pinctada martensii 被引量:10
9
作者 DENG Yuewen YU Ziniu +2 位作者 DU Xiaodong WANG Qingheng FU Shao 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2011年第2期120-125,共6页
In May of 2007,the second generation selected (SS) and control (SC) groups of pearl oyster Pinctada martensii were established by selecting 10% breeders with the largest and mean shell length,respectively,from the... In May of 2007,the second generation selected (SS) and control (SC) groups of pearl oyster Pinctada martensii were established by selecting 10% breeders with the largest and mean shell length,respectively,from the first generation selected group.Growth performance of the SS and SC groups were compared on the basis of measurement data at Days 8,18,60,95,195 and 365.On Day 365,100 individuals (60.0–75.0 mm at shell length) were sampled from each group and then subjected to the experiment where physiological parameters such as filtrate rate,oxygen consumption and ammonia excretion were measured at 15,20,25 and 30°C.The results show that the SS group had significantly larger mean shell length and shell height than the SC group at Days 8,18,60,95,195 and 365 (P 0.05).The genetic gains at different ages varied from 6.0% to 17.0% for shell length and 5.7% to 14.6% for shell height,respectively.At 15,20,25 and 30 ° C,the SS groups had significantly larger filtrate rate than the SC group (P 0.05).At 15 and 25 °C,the differences in oxygen consumption rate between the SS and SC groups were not significant (P 0.05).At 20 and 30 °C,however,the oxygen consumption rate of the SS group was significantly larger than the SC group (P 0.05).At 15,20,25 and 30 °C,there were no significant differences in ammonia excretion rate between the SS and SC groups (P 0.05).The present results indicate that there existed considerable genetic variability in the base population and a further selection could be likely fruitful.Mass selection for faster growth might produce animals that had higher intake of metabolizable energy by virtue of faster filtrating behavior. 展开更多
关键词 Pinctada martensii the second generation selected group GROWTH genetic gains physiological parameters
下载PDF
青少年排球二传的培养和训练 被引量:7
10
作者 沈岚 《南京体育学院学报(自然科学版)》 2002年第3期31-33,共3页
文章介绍了青少年排球二传队员的选材条件和技术、意识及训练的要求和方法,强调了二传队员的重要地位和作用,指出其培养和训练应从青少年抓起。
关键词 青少年 排球 二传队员 选材 训练
下载PDF
美日参比制剂目录的介绍与我国参比制剂目录遴选原则的探讨 被引量:9
11
作者 黄海伟 牛剑钊 +1 位作者 林兰 张启明 《药物分析杂志》 CAS CSCD 北大核心 2013年第11期2009-2012,共4页
美国和日本对参比制剂都有明确的规定,并建立了详细的参比制剂目录,也可称之为"橙皮书",而在我国,尚未建立参比制剂目录。此次《国家药品安全"十二五"规划》仿制药质量一致性评价正好是我国药品参比制剂目录(橙皮书... 美国和日本对参比制剂都有明确的规定,并建立了详细的参比制剂目录,也可称之为"橙皮书",而在我国,尚未建立参比制剂目录。此次《国家药品安全"十二五"规划》仿制药质量一致性评价正好是我国药品参比制剂目录(橙皮书)建立的契机。本文对美国和日本参比制剂目录进行了介绍,进一步探讨如何在我国建立参比制剂目录,对参比制剂的遴选方式和遴选流程提出建议。 展开更多
关键词 参比制剂 遴选 橙皮书 美国 日本
原文传递
气相色谱-负化学源质谱联用法测定水产品及食用油中氟乐灵的残留量 被引量:9
12
作者 王莉 夏广辉 +5 位作者 沈伟健 吴斌 张睿 陆慧媛 沈崇钰 赵增运 《色谱》 CAS CSCD 北大核心 2014年第3期314-317,共4页
建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取,4℃冷藏后,采用分散型固相萃取法净化,由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证... 建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取,4℃冷藏后,采用分散型固相萃取法净化,由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证,同位素内标法定量。在1~40μg / L 范围内氟乐灵农药的线性关系良好;方法定量限(LOQ)为0.02μg / kg;对鳗鱼、烤鳗、梭子蟹、小龙虾、猪油和橄榄油等6种复杂基质进行1.0、2.0和3.0μg / kg 等3个水平的添加回收试验,平均回收率均处于80%~100%之间,RSD≤10.3%;无干扰现象出现。该方法可作为水产品及食用油中氟乐灵残留检测的确证方法。 展开更多
关键词 分散型固相萃取 气相色谱-负化学离子源质谱联用 选择离子监测 氟乐灵 水产品 食用油 disperse solid phase extraction( DSPE) gas chromatography-negative chemical ionization mass SPECTROMETRY ( GC-MS NCI ) selected ion monitoring ( SIM )
下载PDF
Inflammation-associated microsatellite alterations:Mechanisms and significance in the prognosis of patients with colorectal cancer 被引量:7
13
作者 Minoru Koi Stephanie S Tseng-Rogenski John M Carethers 《World Journal of Gastrointestinal Oncology》 SCIE CAS 2018年第1期1-14,共14页
Microsatellite alterations within genomic DNA frameshift as a result of defective DNA mismatch repair(MMR). About 15% of sporadic colorectal cancers(CRCs) manifest hypermethylation of the DNA MMR gene MLH1, resulting ... Microsatellite alterations within genomic DNA frameshift as a result of defective DNA mismatch repair(MMR). About 15% of sporadic colorectal cancers(CRCs) manifest hypermethylation of the DNA MMR gene MLH1, resulting in mono-and di-nucleotide frameshifts to classify it as microsatellite instability-high(MSI-H) and hypermutated, and due to frameshifts at coding microsatellites generating neo-antigens, produce a robust protective immune response that can be enhanced with immune checkpoint blockade. More commonly, approximately 50% of sporadic nonMSI-H CRCs demonstrate frameshifts at di-and tetra-nucleotide microsatellites to classify it as MSIlow/elevated microsatellite alterations at selected tetranucleotide repeats(EMAST) as a result of functional somatic inactivation of the DNA MMR protein MSH3 via a nuclear-to-cytosolic displacement. The trigger for MSH3 displacement appears to be inflammation and/or oxidative stress, and unlike MSI-H CRC patients, patients with MSI-L/EMAST CRCs show poor prognosis. These inflammatory-associated microsatellite alterations are a consequence of the local tumor microenvironment, and in theory, if the microenvironment is manipulated to lower inflammation, the microsatellite alterations and MSH3 dysfunction should be corrected. Here we describe the mechanisms and significance of inflammatory-associated microsatellite alterations, and propose three areas to deeply explore the consequences and prevention of inflammation's effect upon the DNA MMR system. 展开更多
关键词 MICROSATELLITE instability MICROSATELLITE stable Elevated MICROSATELLITE alterations at selected TETRANUCLEOTIDE REPEATS COLORECTAL cancer MISMATCH repair INFLAMMATION MSH3
下载PDF
Investigating on casting mold (or core) making with coated sand by the selected laser sintering 被引量:6
14
作者 Zitian FAN Naiyu HUANG +1 位作者 Yan LI Zhili LIU 《China Foundry》 SCIE CAS 2004年第2期122-126,共5页
Using a special coated sand as the material of the selected laser sintering (SLS), the authors test and investigate the strength change of the test samples in terms of different sintering parameters (scanning speed, l... Using a special coated sand as the material of the selected laser sintering (SLS), the authors test and investigate the strength change of the test samples in terms of different sintering parameters (scanning speed, laser power, sintering thickness, and so on). The characteristics of coated sand hardening by laser beam are analyzed. The sintered mold (or core) for given casting is poured with molten metal. 展开更多
关键词 rapid prototyping selected laser sintering(SLS) laser scanning casting mold(core) technological parameters
下载PDF
Thermal preference, thermal tolerance and the thermal dependence of digestive performance in two Phrynocephalus lizards (Agamidae), with a review of species studied 被引量:7
15
作者 Yanfu QU Hong LI +2 位作者 Jianfang GAO Xuefeng XU Xiang JI 《Current Zoology》 SCIE CAS CSCD 北大核心 2011年第6期684-700,共17页
We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards (P. frontalis and P. versicolor), and compared data among lizards so far s... We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards (P. frontalis and P. versicolor), and compared data among lizards so far studied worldwide. Mean values for selected body temperature (Tsel) and critical thermal maximum (CTMax) were greater in P versicolor, whereas mean values for critical thermal minimum (CTMin) did not differ between the two species. The two lizards differed in food intake, but not in food passage time, apparent digestive coefficient (ADC) and assimilation efficiency (AE), across the experimental tem- peratures. Four general conclusions can be drawn from published data. Firstly, thermal preference and thermal tolerance differ among lizards differing in distribution, temporal activity pattern and habitat use. Lizards in thermally more variable regions are better able to tolerate low and high temperatures. Diurnal lizards generally select higher body temperatures than nocturnal lizards, and lizards using habitats with direct sun exposure generally selected higher body temperatures and are better able to tolerate high temperatures. Secondly, CTMax is positively correlated with Tsel. Lizards more likely exposed to extremely high temperatures while active select higher body temperatures than those using shaded habitats. Thirdly, the effects of body temperature on food intake, food passage time, ADC and AE differ among lizards, but it seems to be common among lizards that ADC and AE are less thermally sensitive than food intake and food passage time. Lastly, ADC is dependent on the type of food ingested, with insectivorous lizards digesting food more efficiently than herbivorous lizards 展开更多
关键词 LIZARDS selected body temperature Critical thermal limits Food intake Food passage time Apparent digestivecoefficient Assimilation efficiency
原文传递
芽菜用小粒大豆新品种吉育109的选育 被引量:7
16
作者 马晓萍 邱红梅 +4 位作者 杨振宇 陈健 高淑芹 侯云龙 王跃强 《大豆科技》 2015年第5期56-58,共3页
大豆新品种吉育109是吉林省大豆研究中心育成的芽菜用大豆新品种。区域试验平均产量2 196.2公斤/公顷,较对照品种吉育105增产13.1%。生产试验平均产量2 318.2公斤/公顷,较对照品种吉育105增产14.3%。该品种为亚有限、百粒重12.8克,为芽... 大豆新品种吉育109是吉林省大豆研究中心育成的芽菜用大豆新品种。区域试验平均产量2 196.2公斤/公顷,较对照品种吉育105增产13.1%。生产试验平均产量2 318.2公斤/公顷,较对照品种吉育105增产14.3%。该品种为亚有限、百粒重12.8克,为芽菜用小粒大豆品种。抗逆性强、早熟、稳产,有广阔的推广前景。 展开更多
关键词 芽菜用小粒大豆 吉育109 选育
下载PDF
路易·艾黎与杜甫 被引量:7
17
作者 刘晓凤 王祝英 《杜甫研究学刊》 2009年第4期95-101,108,共8页
新西兰人路易.艾黎(Rewi Alley)是中国人民的忠实朋友,为中国的解放和建设事业奉献了一生。他热爱中国文化,深入学习和研究中国历史,并且不断向外介绍中国优秀文化,将大量的中国古典诗歌翻译成英文,介绍给英语世界。他尤其喜爱杜甫诗歌... 新西兰人路易.艾黎(Rewi Alley)是中国人民的忠实朋友,为中国的解放和建设事业奉献了一生。他热爱中国文化,深入学习和研究中国历史,并且不断向外介绍中国优秀文化,将大量的中国古典诗歌翻译成英文,介绍给英语世界。他尤其喜爱杜甫诗歌,尊崇杜甫精神,他创作诗歌怀念诗圣,寻访诗圣遗迹,将杜甫诗歌翻译成英文,他的《杜甫诗选》是向英语世界读者专门介绍诗圣诗歌和诗圣伟大精神的翻译著作。与他之前的其他杜诗译者相比,艾黎是位特别的杜诗翻译者,他长期居住在中国,他对中国传统文化有深入的了解,对中国人民充满感情。他推重杜甫,认同诗圣精神,并且身体力行,他在中国学习和工作的过程也是他实践诗圣精神的过程。 展开更多
关键词 路易·艾黎 《杜甫吟》 《杜甫诗选》(DU FU selected POEMS) 实践杜甫精神
下载PDF
实现自我存在的历程——《小王子》的存在主义解读 被引量:7
18
作者 刘晓倩 《曲靖师范学院学报》 2011年第1期45-49,共5页
法国著名童话作家圣.埃克苏佩里的童话《小王子》,充分地体现了一整套20世纪以萨特为代表的法国存在主义理论。运用存在主义理论中关于行动与存在、自由与选择、主体与客体以及荒诞等概念,对《小王子》的文本进行仔细的解读,可以得出这... 法国著名童话作家圣.埃克苏佩里的童话《小王子》,充分地体现了一整套20世纪以萨特为代表的法国存在主义理论。运用存在主义理论中关于行动与存在、自由与选择、主体与客体以及荒诞等概念,对《小王子》的文本进行仔细的解读,可以得出这样的结论:小王子的整个游历的过程就是一个实现自我存在的历程。 展开更多
关键词 童话 小王子 存在主义 行动 选择 荒诞
下载PDF
Complex positive selection pressures drive the evolution of HIV-1 with different co-receptor tropisms 被引量:5
19
作者 ZHANG ChiYu DING Na +1 位作者 CHEN KePing YANG RongGe 《Science China(Life Sciences)》 SCIE CAS 2010年第10期1204-1214,共11页
HIV-1 co-receptor tropism is central for understanding the transmission and pathogenesis of HIV-1 infection. We performed a genome-wide comparison between the adaptive evolution of R5 and X4 variants from HIV-1 subtyp... HIV-1 co-receptor tropism is central for understanding the transmission and pathogenesis of HIV-1 infection. We performed a genome-wide comparison between the adaptive evolution of R5 and X4 variants from HIV-1 subtypes B and C. The results showed that R5 and X4 variants experienced differential evolutionary patterns and different HIV-1 genes encountered various positive selection pressures, suggesting that complex selection pressures are driving HIV-1 evolution. Compared with other hypervariable regions of Gp120, significantly more positively selected sites were detected in the V3 region of subtype B X4 variants, V2 region of subtype B R5 variants, and V1 and V4 regions of subtype C X4 variants, indicating an association of positive selection with co-receptor recognition/binding. Intriguingly, a significantly higher proportion (33.3% and 55.6%, P【0.05) of positively selected sites were identified in the C3 region than other conserved regions of Gp120 in all the analyzed HIV-1 variants, indicating that the C3 region might be more important to HIV-1 adaptation than previously thought. Approximately half of the positively selected sites identified in the env gene were identical between R5 and X4 variants. There were three common positively selected sites (96, 113 and 281) identified in Gp41 of all X4 and R5 variants from subtypes B and C. These sites might not only suggest a functional importance in viral survival and adaptation, but also imply a potential cross-immunogenicity between HIV-1 R5 and X4 variants, which has important implications for AIDS vaccine development. 展开更多
关键词 HIV-1 co-receptor tropism adaptive evolution positively selected site R5 and X4 GP120 EPITOPES
原文传递
Effects of Multiple Strengthening Treatments on Mechanical Properties and Stability of Nanoscale Precipitated Phases in an Aluminum-Copper-Lithium Alloy 被引量:5
20
作者 S.Ahmadi H.Arabi A.Shokuhfar 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2010年第12期1078-1082,共5页
Effects of multiple strengthening treatments (i.e. ag mechanical properties and stability of nanoscale prec in this research. Various tests such as hardness, tensi ng either at three or four consecutive temperatures... Effects of multiple strengthening treatments (i.e. ag mechanical properties and stability of nanoscale prec in this research. Various tests such as hardness, tensi ng either at three or four consecutive temperatures) on pitated phases in an AA2090 alloy have been evaluated e, electrical resistance, differential scanning calorimetric (DSC), and transmission electron microscopy (TEM) have been performed. The results show that the ultimate tensile strength (UTS) and the yield strength of the samples aged at four consecutive temperatures (i.e. natural aging+190℃+150℃+100℃) can be increased approximately to 660 and 610 MPa, respectively. It is also found that precipitation of T1 phase occurs during multiple aging process of the alloy and the higher amounts of enthalpies shown in DSC charts are linked to higher volume fraction of this precipitate. Furthermore, TEM observations reveal that T1 phase has plate shape morphology and its crystal structure is in the form of hcp with lattice parameters of a=0.467 nm and c=0.878 nm. 展开更多
关键词 Multiple strengthening Thermo mechanical treatment (TMT) selected area electron diffraction (SAED) pattern Inter planar spacing (d)
原文传递
上一页 1 2 250 下一页 到第
使用帮助 返回顶部