982 resultados para 332.224


Relevância:

10.00% 10.00%

Publicador:

Resumo:

把1870-2001年来自美国"现代灵长类文献题录数据库"、"维普中文数据库"及"中国灵长类研究文献题录"的资料按4个时期(I:1870-1949;Ⅱ:1950-1965;Ⅲ:1966-1977;Ⅳ:1978-2001)分类整理.此外,使用了"科学引文数据库(扩展版)".结果如下:(1)1870-2001年共有20 52篇文献,2个文献数量高峰分别出现于1950-1965和1978-2001年;科研部门所发表的论文占54.2%,并随时间而增加;而国外部门则随之减少.(2)2 052篇文献中,超过9%的文献为SCI所收录,其中1966-1977年被SCI收录的文献百分比最高;在全部被SCI收录的文献中又以科研部门的占优势(59.1%);但国外部门则以其30.1%的文献被SCI收录而领先.(3)统计了灵长类研究9个领域文献百分比及其变化,其中1978-2001间生态学和行为、神经生物学、繁殖和饲养快速发展;化石灵长类、形态学和解剖学减少;分类及分布、细胞及分子进化显得不甚突出;在第Ⅱ时期和第Ⅳ时期疾病防治研究相当多;保护生物学得到越来越多的关注.第Ⅳ时期作者数量最多,但每个作者的文献平均数却不如第Ⅰ时期.一般地说,在SCI收录的作者中以中国作者居多,但在第I时期唯一被SCI收录的作者则是一名外国学者;在第Ⅲ时期外国作者占被收录作者数的60%.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

细胞膜流动性通常是指膜脂质的流动性。神经细胞膜功能的正常进行要求膜脂质保持适宜的流动状 态。膜流动性改变将导致膜电位、离子通透性、跨膜物质运输、信号转导等一系列改变。老年动物及阿尔茨海 默氏病(AD) 患者脑神经细胞膜流动性显著降低, 主要与自由基增多引起的脂质过氧化反应、神经细胞钙平衡 失调有关, 此外, 还与其脑内神经元上的受体密度、β- 淀粉样蛋白沉积有关。促智药(吡咯烷酮类、人参皂 甙、银杏叶提取物EGb761) 能明显增强老年动物及AD 患者脑神经细胞膜的流动性。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

:本文以野生猕猴为实验对象,以血清皮质 醇含量为指标,研究了野生猕猴 被捕获与给予氯丙嗪、Vc等药物后上述指标的变化。结果 表明:(1)野生猕猴在被捕获 后的1~2周内,血清皮质醇一直维持在一个高水平状态(24.7 8±0.20μg/dl,24.88 ±0.58μg/dl);(2)氯丙嗪可使动物行为处于一种安静状态, 但 并不降低血清皮质醇水 平(28.73±6.16μg/dl),(3)Vc可改善动物的精神状态,使血清 皮质醇略低(21.00 ±2.90μg/dl)(P>0.05),(4)氯丙嗪和Vc合用后,血清皮质 醇与单独使用氯丙嗪无明显 差异(28.07±4.45μg/dl)。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

:用紫撬泽兰精油的20℃~150。C,150℃一200℃,20.0℃,230℃.230屯。300℃和300℃以上馏协,分剐以 稚.簦嘴,L的熏蒸浓爰楚理米象、玉采象、簿豆象牵蚕熹象,螬幕表磷凄5争犍静中,娃15。℃~200℃馏傍转荣虫活性 最高,其洗是20℃一150℃和200℃~230气馏份,而300℃以上馏份的杀虫活性靛低。进一步的生测结装表明.150屯一 200℃增傍对米象、玉来氧、绿黛象和善豆象24h的l(葡分莉为15 5li4,17.8124,培.0302和16.2671mg/Lo

Relevância:

10.00% 10.00%

Publicador:

Resumo:

该文记述果蝇属拱背果蝇亚属黑色拱背果蝇种组三新种: 锚形拱背果蝇 Drosophila (Lordiphosa) archoroides sp. nov, 毛拱背果蝇 Drosophila (Lordiphosa) penicilla sp. nov. 和钳拱背果蝇 Drosophila (Lordiphosa) forcipata sp. nov.. 附中国10个种的检索表。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

通过分析咖啡旋皮天牛 Acalolepta cervinus (Hope)和咖啡灭字虎天牛 Xylotrechus quadripes Chevr.的生态对策、种间竞争策略,并结合有害生物综合管理(IPM)理论、咖啡林生态系统的特性、咖啡天牛的发生特点,提出了咖啡天牛的防治策略。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The reproductive traits of Gymnocypris selincuoensis from Selincuo Lake and its tributaries were investigated in 1997 and 1998. The youngest mature male was age 7 with a standard length (SL) of 172.0 mm, and the youngest mature female was age 8 with a SL of 194.0 mm. The L(50)s Of SL and age at first maturity were respectively 250.32 mm and age 9 for males and 224.71 mm and age 8 for females. The gonadosomatic index (GSI) significantly changed with seasons for mature individuals but not for immature individuals. GSIs of mature females at stages IV and V of ovary development increased with SL and reached a maximum value at the SL range from 370 mm to 390 mm; the GSIs of mature males were negatively correlated with SL. The breeding season lasted from early April to early August. Egg size did not significantly change with SL but increased with the delay of spawning. The individual absolute fecundity varied from 1,341 to 28,002 eggs (mean 12,607+/-7,349), and the individual relative fecundity varied from 6.4 to 42.0 eggs.g(-1) (mean 25.5+/-9.7). The individual fecundity increased with total body weight; it also increased with SL for those of SL less than 370 mm. There was a rest of spawning for mature individuals.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A chymotrypsin inhibitor, designated NA-CI, was isolated from the venom of the Chinese cobra Naja atra by three-step chromatography. It inhibited bovine (x-chymotrypsin with a K-i of 25 nM. The molecular mass of NA-CI was determined to be 6403.8 Da by matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) analysis. The complete amino acid sequence was determined after digestion of S-carboxymethylated inhibitor with Staphylococcus aureus V8 protease and porcine trypsin. NA-CI was a single polypeptide chain composed of 57 amino acid residues. The main contact site with the protease (PI) has a Phe, showing the specificity of the inhibitor. NA-CI shared great similarity with the chymotrypsin inhibitor from Naja naja venom (identities = 89.5%) and other snake venom protease inhibitors. (C) 2003 Elsevier Inc. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study investigates the structural behavior of precracked reinforced concrete (RC) T-beams strengthened in shear with externally bonded carbon fiber-reinforced polymer (CFRP) sheets. It reports on seven tests on unstrengthened and strengthened RC T-beams, identifying the influence of load history, beam depth, and percentage of longitudinal steel reinforcement on the structural behavior. The experimental results indicate that the contributions of the external CFRP sheets to the shear force capacity can be significant and depend on most of the investigated variables. This study also investigates the accuracy of the prediction of the fiber-reinforced polymer (FRP) contribution in ACI 440.2R-08, UK Concrete Society TR55, and fib Bulletin 14 design guidelines for shear strengthening. A comparison of predicted values with experimental results indicates that the guidelines can overestimate the shear contribution of the externally bonded FRP system. © 2012, American Concrete Institute.

Relevância:

10.00% 10.00%

Publicador:

Relevância:

10.00% 10.00%

Publicador:

Relevância:

10.00% 10.00%

Publicador:

Relevância:

10.00% 10.00%

Publicador: