982 resultados para 332.251
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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%.
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: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
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鲇形目鱼类包括31个科, 二千余种, 分布全球。我国产鲇类鱼11科、28属、111种。文中给出了在我国的科级分布表,分布最广的是鲇科,主要集中在华东区和华南区,是宁蒙区的唯一鲇类鱼 代表;以下按次序是Chang科、Zhao科、胡子鲇科、长臀Wei科、刀鲇科、Mang科和粒鲇科等。该文还列出了鲇类鱼在我国的种级分布表,按种数列前五位 的是:怒澜亚区(44种)、珠江亚区(34种)、江淮亚区(25种)、川西亚区(22种)和浙闽亚区(20种)。提示,华南区是我国鲇类鱼的分布中心。表3参3
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用力偏倚(FB)法,由体系的晶体点阵构型出发到达平衡态所需的循环数为Metroplis法的武分之二。为了得到较好的结构信息所需的构型数也仅为后者的五分之二。虽然每个循环所需机时为Metropolis法的1.6倍,仍是一加速收敛的好方法。此外进一步支持了以分子的平移扩散作为判别抽样效率的判据,指出接受几率在0.33—0.36之间的步长可能是合适的。此外还统计了和丙氨酸作用大于2kcal/mol的分子座标,使它们与丙氨酸-水分子径向分布图的峰值相对应。图2表2参9
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描述了采自四川秀山和贵州梵净山的蝗虫一新属二新种。命名为: 异翅蝗属Heferopterus gen. nov.新属和贵州扁角蚱Flatocerus guizhouensis sp. nov.新种。模式标本存作者单位。图2表1参7
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鸡胚背根神经节培养法是测定神经生长因子(NGF)和神经营养因子活性的重要方法。我们通过考察培养基、鸡血浆和鸡胚浸液的比例、背根神经节部位、培养时间等条件对NGF刺激神经节生长的影响,从而建立了一套检测NGF活性的优化条件。在含20%鸡血浆和15%鸡胚浸液的DMEM的培养基中,利用伊莎褐鸡胚腰部的背根神经节,在终浓度为30ng/ml 的蛇毒NGF的刺激下,培养36h可以得到理想的实验结果。该条件重复性好、分辨率高、简单实用。
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Sexual dimorphism in the dentition and skeleton of the four extant species of snub-nosed langurs, Rhinopithecus (R.) bieti, R. (R.) brelichi, R. (R.) roxellana and R. (Presbytiscus) avunculus, was studied. The species shared a similar general pattern of sexual dimorphism, but were found to differ in respects that appear to reflect the influence of disparate socioecological and environmental factors. All the species showed marked canine dimorphism, but the very high degree of canine dimorphism in R. bieti appeared to be due to the intensity of intermale competition for mates during a temporally restricted breeding season, and possibly also to the intensity of competition between males for other resources during other times of the year. Sexual dimorphism in the postcranial skeleton of Rhinopithecus species was also most pronounced in R. bieti and may be related to the relatively higher frequency of terrestrial locomotion in males of the species. (C) 1995 Wiley-Liss, Inc.
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Globally unstable wakes with co-flow at intermediate Reynolds numbers are studied, to quantify important spatial regions for the development and control of the global instability. One region of high structural sensitivity is found close to the inlet for all wakes, in agreement with previous findings for cylinder wakes. A second, elongated region of high structural sensitivity is seen downstream of the first one for unconfined wakes at Re = 400. When base flow modifications are considered, a spatially oscillating sensitivity pattern is found inside the downstream high structural sensitivity region. This implies that the same change in the base flow can either destabilize or stabilize the flow, depending on the exact position where it is applied. It is shown that the sensitivity pattern remains unchanged for different choices of streamwise boundary conditions and numerical resolution. Actual base flow modifications are applied in selected configurations, and the linear global modes recomputed. It is confirmed that the linear global eigenvalues move according to the predicted sensitivity pattern for small amplitude base flow modifications, for which the theory applies. We also look at the implications of a small control cylinder on the flow. Only the upstream high sensitivity region proves to be robust in terms of control, but one should be careful not to disturb the flow in the downstream high sensitivity region, in order to achieve control. The findings can have direct implications on the numerical resolution requirements for wakes at higher Reynolds numbers. Furthermore, they provide one more possible explanation to why confined wakes have a more narrow frequency spectrum than unconfined wakes.