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   37篇
  免费   1篇
  国内免费   2篇
  2024年   1篇
  2020年   1篇
  2018年   1篇
  2017年   2篇
  2014年   1篇
  2013年   4篇
  2012年   3篇
  2011年   3篇
  2009年   2篇
  2008年   3篇
  2007年   3篇
  2006年   2篇
  2005年   2篇
  1998年   1篇
  1997年   1篇
  1991年   2篇
  1985年   1篇
  1981年   1篇
  1974年   1篇
  1968年   1篇
  1958年   3篇
  1957年   1篇
排序方式: 共有40条查询结果,搜索用时 15 毫秒
31.
对产自越南的荨麻科楼梯草属植物一新种金喜楼梯草(Elatostema kimhyense Y.G.Wei & V.T.Do)作了描述和绘图。该种生长于海拔350~400和1 100~1 200 m的石灰岩山地林下。该新种与越南楼梯草(E.vietnamense Q.Lin & L.D.Duan)接近,区别在于其拥有肉质茎,羽状脉,叶背面、苞片和小苞片被微硬毛。  相似文献   
32.
ldne is a program with a Visual Basic interface that implements a recently developed bias correction for estimates of effective population size (N(e) ) based on linkage disequilibrium data. The program reads genotypic data in standard formats and can accommodate an arbitrary number of samples, individuals, loci, and alleles, as well as two mating systems: random and lifetime monogamy. ldne calculates separate estimates using different criteria for excluding rare alleles, which facilitates evaluation of data for highly polymorphic markers such as microsatellites. The program also introduces a jackknife method for obtaining confidence intervals that appears to perform better than parametric methods currently in use.  相似文献   
33.
该文报道了中国苦苣苔科(Gesneriaceae)一新记录属——四轮苣苔属(Tetraphyllum Griff. ex C. B. Clarke)。该新记录属,即四轮苣苔属仅有3种,其中密花四轮苣苔[T. confertiflorum(Drake)B. L. Burtt]在我国首次记录。该研究提供了该属的形态描述和分种区别特征,并提供了该种的详细形态描述及彩色照片。凭证标本馆藏于广西植物研究所标本馆(IBK)和上海辰山植物标本馆(CSH)。  相似文献   
34.
1. The consequences of symbiont transmission strategies are better understood than their adaptive causes. 2. Feather mites are permanent ectosymbionts of birds assumed to be transmitted mainly vertically from parents to offspring. The transmission of Proctophyllodes doleophyes Gaud (Astigmata, Proctophyllodidae) was studied in two European populations of pied flycatchers, Ficedula hypoleuca Pallas (Passeriformes, Muscicapidae). 3. The vertical transmission of this mite species is demonstrated here with an acaricide experiment. This study also compared (for two distant populations during 4 years) patterns in reductions in mite intensity in adult birds, from egg incubation to chick‐rearing periods, with the predictions of three hypotheses on how host survival prospects and mite intraspecific competition might drive feather mites' transmission strategy. 4. The results are in agreement with previous studies and show that feather mites transmit massively from parents to chicks. 5. The magnitude of the transmission was closer to that predicted by the hypothesis based on intraspecific competition, while a bet‐hedging strategy is also partially supported.  相似文献   
35.
Living culture forms of “Leptomonas pessoai” cross protected mice against T. cruzi challenge infection. Circulating antibodies have been detected in the immunized mice by immunodiffusion analysis, passive hemagglutination, complement fixation test and antibody binding assay; these antibodies cross reacted with T. cruzi extracts. A cellular immune response was indicated by leucocyte migration inhibition using L. pessoai and T. cruzi antigens, strongly suggesting a role for cell-mediated immunity in the mechanism of protection induced by L. pessoai.  相似文献   
36.
37.
Sequence variation at the intron-1 of the voltage-gated sodium channel gene in Anopheles gambiae M- and S-forms from Cameroon was assessed to explore the number of mutational events originating knockdown resistance ( kdr ) alleles. Mosquitoes were sampled between December 2005 and June 2006 from three geographical areas: (i) Magba in the western region; (ii) Loum, Tiko, Douala, Kribi, and Campo along the Atlantic coast; and (iii) Bertoua, in the eastern continental plateau. Both 1014S and 1014F kdr alleles were found in the S-form with overall frequencies of 14% and 42% respectively. Only the 1014F allele was found in the M-form at lower frequency (11%). Analysis of a 455 bp region of intron-1 upstream the kdr locus revealed four independent mutation events originating kdr alleles, here named MS1 -1014F, S1-1014S and S2-1014S kdr- intron-1 haplotypes in S-form and MS3-1014F kdr- intron-1 haplotype in the M-form. Furthermore, there was evidence for mutual introgression of kdr 1014F allele between the two molecular forms, MS1 and MS3 being widely shared by them. Although no M/S hybrid was observed in analysed samples, this wide distribution of haplotypes MS1 and MS3 suggests inter-form hybridizing at significant level and emphasizes the rapid diffusion of the kdr alleles in Africa. The mosaic of genetic events found in Cameroon is representative of the situation in the West–Central African region and highlights the importance of evaluating the spatial and temporal evolution of kdr alleles for a better management of insecticide resistance.  相似文献   
38.
On importance resampling for the bootstrap   总被引:1,自引:0,他引:1  
DO  KIM-ANH; HALL  PETER 《Biometrika》1991,78(1):161-167
  相似文献   
39.
The production of mutations in cellular oncogenes such as ras is involved in the development of many human cancers. These mutations result in the expression of mutant forms of the encoded p21 protein which can potentially serve as a biomarker for this carcinogenic process. Workers exposed to vinyl chloride (VC) who are at risk for the development of the sentinel neoplasm angiosarcoma of the liver (ASL) represent a model population for the study of such a mutant p21ras biomarker, since VC is known to cause a specific ras mutation in ASL. In order to determine the relationship between VC exposure and this biomarker, serum samples from a cohort of 225 French VC workers and 111 age-sex-race-smoking-drinking matched unexposed controls were examined for the presence of mutant p21ras by immunoblotting with a mouse monoclonal antibody specific for the mutant protein. Stratifying the exposed workers by degree of VC exposure in estimated ppm-years by quartiles yielded a statistically significant trend for increasing odds ratio for sero-positivity of the p21ras biomarker with increasing exposure. These results suggest that this serum biomarker is related to VC exposure and may be an early indicator of carcinogenic risk in exposed individuals.  相似文献   
40.
ADRIAN A. BARNETT  SARAH A. BOYLE  MARILYN M. NORCONK  SUZANNE PALMINTERI  RICARDO R. SANTOS  LIZA M. VEIGA  THIAGO H.G. ALVIM  MARK BOWLER  JANICE CHISM  ANTHONY DI FIORE  EDUARDO FERNANDEZ‐DUQUE  ANA C. P. GUIMARÃES  AMY HARRISON‐LEVINE  TORBJØRN HAUGAASEN  SHAWN LEHMAN  KATHERINE C. MACKINNON  FABIANO R. DE MELO  LEANDRO S. MOREIRA  VIVIANE S. MOURA  CARSON R. PHILLIPS  LILIAM P. PINTO  MARCIO PORT‐CARVALHO  ELEONORE Z. F. SETZ  CHRISTOPHER SHAFFER  LÍVIA RODRIGUES DA SILVA  SULEIMA DO S. B. DA SILVA  RAFAELA F. SOARES  CYNTHIA L. THOMPSON  TATIANA M. VIEIRA  ARIOENE VREEDZAAM  SUZANNE E. WALKER‐PACHECO  WILSON R. SPIRONELLO  ANN MACLARNON  STEPHEN F. FERRARI 《American journal of primatology》2012,74(12):1106-1127
Neotropical monkeys of the genera Cacajao, Chiropotes, and Pithecia (Pitheciidae) are considered to be highly arboreal, spending most of their time feeding and traveling in the upper canopy. Until now, the use of terrestrial substrates has not been analyzed in detail in this group. Here, we review the frequency of terrestrial use among pitheciin taxa to determine the ecological and social conditions that might lead to such behavior. We collated published and unpublished data from 14 taxa in the three genera. Data were gleaned from 53 published studies (including five on multiple pitheciin genera) and personal communications of unpublished data distributed across 31 localities. Terrestrial activity was reported in 61% of Pithecia field studies (11 of 18), in 34% of Chiropotes studies (10 of 29), and 36% of Cacajao studies (4 of 11). Within Pithecia, terrestrial behavior was more frequently reported in smaller species (e.g. P. pithecia) that are vertical clingers and leapers and make extensive use of the understory than in in the larger bodied canopy dwellers of the western Amazon (e.g. P. irrorata). Terrestrial behavior in Pithecia also occurred more frequently and lasted longer than in Cacajao or Chiropotes. An apparent association was found between flooded habitats and terrestrial activity and there is evidence of the development of a “local pattern” of terrestrial use in some populations. Seasonal fruit availability also may stimulate terrestrial behavior. Individuals also descended to the ground when visiting mineral licks, escaping predators, and responding to accidents such as a dropped infant. Overall, the results of this review emphasize that terrestrial use is rare among the pitheciins in general and is usually associated with the exploitation of specific resources or habitat types. Am. J. Primatol. 74:1106‐1127, 2012. © 2012 Wiley Periodicals, Inc.  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