首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   51篇
  免费   1篇
  国内免费   12篇
  2020年   1篇
  2017年   2篇
  2016年   1篇
  2015年   1篇
  2014年   3篇
  2013年   6篇
  2012年   1篇
  2011年   5篇
  2010年   1篇
  2009年   4篇
  2008年   7篇
  2007年   6篇
  2006年   5篇
  2005年   1篇
  2004年   2篇
  2002年   1篇
  2001年   1篇
  2000年   2篇
  1998年   2篇
  1997年   2篇
  1996年   1篇
  1994年   2篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
  1988年   3篇
  1984年   1篇
排序方式: 共有64条查询结果,搜索用时 15 毫秒
1.
菲菊头蝠回声定位信号特征及下丘神经元频率调谐   总被引:1,自引:1,他引:0  
研究了菲菊头蝠自由飞行状态下的回声定位信号和下丘神经元的声反应特性。菲菊头蝠在自由飞行时发射的CF/FM型回声定位叫声含2-3个谐波,主频为105.3±1.7kHz,时程为39.5±9.6ms,脉冲间隔为73.9±16.0ms。在所记录到的159个下丘神经元中,E型(Echolocation)神经元为32.7%(52/159),其中CF1型(Constantfrequency)占11.3%(18/159),FM1型(Frequencymodulated)占20.1%(32/159),FM2型占1.3%(2/159);NE型(Nonecholocation)神经元的比例为67.3%(107/159)。这些神经元的最佳频率(Bestfrequency,BF)与记录深度之间存在线性关系(r=0.9471,P<0.01)。E型神经元的深度范围为349-1855(1027.5±351.6)μm,阈值范围为6-74(43.1±14.5)dBSPL,潜伏期范围为10.0-26.0(14.6±3.8)ms。NE型神经元的分别为93.0-1745.0(733.3±290.3)μm、2-70(36.5±23.8)dBSPL、5.0-23.0(13.5±3.7)ms。记录到的53个IC神经元的调谐曲线(Frequencytuningcurve,FTC)均为开放型,51个为单峰型,2个为双峰型。单峰型神经元中大部分为狭窄型(Q10dB>5),占70.6%(36/51),E型神经元全部为狭窄型,Q10dB为10.4±7.1(5.5-31.6),其中CF1型为18.3±11.2(5.5-31.6),FM1型为8.7±4.7(5.5-24.3),FM2型为6.9±0.3(6.7-7.1);NE型神经元既有宽阔型也有狭窄型,Q10dB为6.6±5.1(1.6-25.6)。两个双峰型FTC主、副峰分别偏向高、低频区,高频边对应的是E型神经元。  相似文献   
2.
This study describes the postnatal development of body mass, forearm length and epiphyseal phalangeal gap in a free ranging population of the Long-fingered Bat, Miniopterus schreibersii pallidus Thomas, 1907, in a maternity roost in the Mahidasht cave in western Iran. The pups at birth had a mean body mass of 3.74?±?0.09 g and forearm length of 24.3?±?0.31mm. The length of forearm and body mass increased linearly during first two weeks, and thereafter maintained an apparent stability. The epiphyseal gap of the fourth metacarpal phalangeal joint increased until the thirteenth day, then decreased linearly until the 70th day and thereafter fused. The rate of body mass gain and forearm growth during the first 13 days was 0.54 g/day and 1.39 mm/day, respectively. Initiation of flight occurred three weeks after birth. A method of estimating age was derived from the values of the forearm length and the total gap of the fourth metacarpal-phalangeal joint during the pre-flight and post-flight periods.  相似文献   
3.
采用6种不同的培养基,分别于25℃、32℃、42℃以及50℃培养分离从而对某一中国白酒酒曲中的丝状真菌菌群进行研究.从酒曲中共分离得到886株丝状真菌,分属于接合菌,子囊菌和无性型真菌的20属,45种.其中最为丰富的是无性型真菌(28种),其次是接合菌(10种)和子囊菌(7种).对发酵起主要作用的为那些嗜热和耐热的种属,包括:宛氏拟青霉,伞枝梨头霉,梳棉状嗜热丝孢菌,微小根毛霉,金孢霉属一种和红曲属的几个种.文中还对一些在发酵中起重要作用的丝状真菌的特性进行了探讨.  相似文献   
4.
回声定位声波地理差异及其形成原因是蝙蝠生态学研究领域一个基本而关键的问题,对于探索物种生存机制、物种形成及其保护具有重要科学意义。本研究从较大地理尺度上(9个地理种群)研究了菲菊头蝠(Rhinolophus pusillus)回声定位声波结构的地理差异,并进一步探讨了影响回声定位声波地理种群差异的因素。结果表明,菲菊头蝠雌性的体型较雄性略大,其主频较高。不同地理种群之间回声定位声波差异明显,包括脉冲持续时间、脉冲间隔、主频以及带宽在不同的地理种群之间均表现出一定程度的差异。进一步分析发现,不同地理种群之间的雌性菲菊头蝠前臂长和体重均与主频呈较弱的负相关,降雨量与雌性的主频呈较强的正相关;而不同地理种群之间的雄性前臂长、体重和降雨量与回声定位声波参数均无相关性;此外,地理距离、温度、湿度均与雌雄回声定位声波参数无相关性。本研究结果表明,菲菊头蝠不同地理种群间的回声定位声波出现明显差异,其中,体型和降雨量为主要影响因子,说明蝙蝠回声定位叫声的进化主要受到了当地生境的影响,表现出动物对不同生境的适应性进化。  相似文献   
5.
6.
研究了石菖蒲4种溶剂无水乙醇、丙酮、乙酸乙酯、石油醚提取物对玉米象、谷蠹、长角扁谷盗和锯谷盗4种储粮害虫的驱避作用和触杀作用。结果表明:石菖蒲4种溶剂提取物对4种试虫均有明显的驱避作用和触杀作用,处理60 h的平均驱避等级均达到Ⅲ级以上,对4种试虫的触杀死亡率均达到41.11%以上。  相似文献   
7.
菲菊头蝠是分布于亚热带和热带的翼手目种类,在中国大陆南部和海南岛有广泛分布。为探讨热带菲菊头蝠是否具有冬眠期(12 月至翌年2 月)储精现象及生殖腺组织结构的变化,对海南岛的菲菊头蝠成年雄蝠和成年雌蝠生殖系统在冬眠期间的变化进行了石蜡切片观察。结果显示:成年雄蝠在冬眠期间附睾内储存大量精子,推测其储存时间超过2 个月;冬眠期间曲细精管横截面积、精子细胞数量和间质细胞数量在冬眠期逐月显著性减少,精原细胞和精母细胞的数量在12 月与翌年1 月间均无显著性变化,而在冬眠末期的2 月显著增多。在雌蝠子宫和卵巢内均未发现精子储存现象,但卵巢内具有初级卵泡和次级卵泡,雄蝠在冬眠期间曲细精管逐月萎缩,但生精上皮精母细胞的数量在冬眠末期明显上升。  相似文献   
8.
微小根毛霉致病株的原生质体形成条件   总被引:9,自引:0,他引:9  
建立了重要医学真菌──肺微小根毛霉的原生质体生成系统。采用溶细胞酶以及蜗牛酶与纤维素酶联合作用的方式获得了大量原生质体,处于指数生长期、生长旺盛的幼龄菌丝对破壁酶比生长缓慢或老龄菌丝更敏感;作为渗透压稳定剂,无机盐类要好于有机物;原生质体的较适生成温度为31℃。  相似文献   
9.
The large bent-wing bat, Miniopterus schreibersii (Kuhl 1819), has a long history of taxonomic uncertainty and many populations are known to be in a state of decline. Microsatellite loci were developed for the taxonomic and population genetic assessment of the Australian complex of this species. Of the 33 primer sets designed for this research, seven (21%) were deemed suitably polymorphic for population-level analyses of the Australian taxa, with five (71%) of these loci revealing moderate to high levels of polymorphism (PIC = 0.56 to 0.91). The cross-taxa utility of the M. schreibersii microsatellite markers was assessed in the microbat (Chiroptera) family Miniopteridae. Sub-species and species covering the Miniopteridae's global distribution (with the exception of the Middle East) were selected, numbering 25 taxa in total. Amplification was successful for 26 loci, of which 20 (77%) were polymorphic. High cross-taxa utility of markers was observed with amplification achieved for all taxa for between four (20%) and 20 (100%) loci, and polymorphism was considered moderate to high (PIC = 0.47-0.91) for 12 (60%) of these loci. The high cross-taxa utility of the microsatellites reported herein reveal versatile and cost-effective molecular markers, contributing an important genetic resource for the research and conservation of Miniopteridae species worldwide.  相似文献   
10.
The endemic fauna of the Comoro Archipelago is composed of a mixture of taxa originating from Africa and Madagascar. Bats are the only native land dwelling mammals on this archipelago, but the biogeographical origins for the vast majority of species within this group are ambiguous. We report here genetic analyses based on two mitochondrial DNA markers to infer the origin of Comorian bats belonging to a reputed species complex of Miniopterus that is further distributed across Africa and Madagascar. Phylogenetic reconstructions show that east African M. minor are not closely related to the insular Miniopterus of Madagascar and the Comoros (Grande Comore and Anjouan). The latter cluster into two distinct, monophyletic clades (Clade 1 and Clade 2). Representatives of these clades occur sympatrically both on the Comoros and on Madagascar, and are distinguished by a large genetic distance (K2P: 9.9% for cytochrome b). No haplotypes are shared between any islands, suggesting the absence of contemporary gene flow. Populations of the widespread Clade 1 are furthermore characterized by a significant inter‐island structure (ΦCT = 0.249), and by high haplotype and nucleotide diversities (h = 0.90–0.98, π = 0.04–0.06). Demographic analyses of Clade 1 suggest secondary contact between two distinct phylogroups (Subclade 1 A and 1B) that reached Grande Comore and Anjouan, and a large, stable population with a long evolutionary history on Madagascar. These results and the current distribution of related lineages suggest that the Comoros were colonized independently at least two or three times by ancestors from Madagascar.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号