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   44篇
  免费   1篇
  2016年   1篇
  2013年   5篇
  2012年   2篇
  2010年   6篇
  2009年   2篇
  2008年   2篇
  2007年   3篇
  2006年   4篇
  2005年   1篇
  2004年   2篇
  2000年   1篇
  1996年   3篇
  1989年   1篇
  1958年   1篇
  1952年   4篇
  1951年   5篇
  1950年   2篇
排序方式: 共有45条查询结果,搜索用时 15 毫秒
1.
2.
This study reports the isolation and characterization of seven highly polymorphic microsatellite loci in Chthamalus montagui (Crustacea, Cirripedia). The loci were isolated from a library constructed from genomic DNA enriched for CA repeats. The markers yielded three to 43 alleles per locus (mean 16.7) in samples averaging 49 individuals. Observed heterozygosity ranged from 0.08 to 0.58 (mean 0.39). These microsatellite loci will be valuable tools for population genetic studies of this species.  相似文献   
3.
Abstract:  Several new specimens of Protoischnurus axelrodorum Carvalho and Lourenço and Araripescorpius ligabuei Campos from the Crato Formation, Brazil, are described. The preservation and recognition of new morphological features allows a re-diagnosis of both species and a modification of their familial placement. Protoischnurus axelrodorum is the oldest species belonging to the scorpionoid family Hemiscorpiidae Pocock (= Ischnuridae Simon; = Liochelidae Fet and Bechly) and the first Cretaceous record. It was originally placed in the extinct family Protoischnuridae Carvalho and Lourenço, which is here synonymized with Hemiscorpiidae. Araripescorpius ligabuei, now assigned to Chactidae Pocock, is the first chactoid recorded for the Cretaceous of Brazil. These findings confirm that the lineages of two modern families date back at least to the Early Cretaceous and, considering their current distribution, were probably present before the break-up of the supercontinent Gondwana. Palaeoecological inferences indicate the presence of tropical habitats in the vicinity of the Crato lake/lagoon.  相似文献   
4.
Eleven polymorphic microsatellite loci were isolated in the passeriform Petronia petronia using the enrichment protocol FIASCO (fast isolation by AFLP of sequences containing repeats). We detected three to 13 alleles per locus in 25 specimens collected from an Italian population. The level of expected heterozygosity ranged from 0.439 to 0.856. One locus is sex linked to the Z chromosome. The total exclusionary probabilities using these loci for the first and the second parent were 0.978 and 0.999, respectively. These are the first microsatellite loci characterized from the rock sparrow that can be used for estimating population structure and for large‐scale parentage analysis.  相似文献   
5.
6.
7.
The therevoid clade represents a group of four families (Apsilocephalidae, Evocoidae, Scenopinidae and Therevidae) of lower brachyceran Diptera in the superfamily Asiloidea. The largest of these families is that of the stiletto flies (Therevidae). A large‐scale (i.e. supermatrix) phylogeny of Therevidae is presented based on DNA sequence data from seven genetic loci (16S, 18S and 28S ribosomal DNA and four protein‐encoding genes: elongation factor 1‐alpha, triose phosphate isomerase, short‐wavelength rhodopsin and the CPSase region of carbamoyl‐phosphate synthase‐aspartate transcarbamoylase‐dihydroorotase). Results are presented from Bayesian phylogenetic analyses of approximately 8.7 kb of sequence data for 204 taxa representing all subfamilies and genus groups of Therevidae. Our results strongly support the sister‐group relationship between Therevidae and Scenopinidae, with Apsilocephalidae as sister to Evocoidae. Previous estimates of stiletto fly phylogeny based on morphology or DNA sequence data, or supertree analysis, have failed to find significant support for relationships among subfamilies. We report for the first time strong support for the placement of the subfamily Phycinae as sister to the remaining Therevidae, originating during the Mid Cretaceous. As in previous studies, the sister‐group relationship between the species‐rich subfamilies Agapophytinae and Therevinae is strongly supported. Agapophytinae are recovered as monophyletic, inclusive of the Taenogera group. Therevinae comprise the bulk of the species richness in the family and appear to be a relatively recent and rapid radiation originating in the southern hemisphere (Australia + Antarctica + South America) during the Late Cretaceous. Genus groups are defined for all subfamilies based on these results.  相似文献   
8.
Upwind orientation flights of codling moth males Cydia pomonella L. to a single source of sex pheromone (E,E)‐8,10‐dodecadienol (codlemone) are significantly reduced when blending it with pheromone antagonists, either with codlemone acetate, (E,E)‐8,10‐dodecadienyl acetate, or with the codlemone isomer (E,Z)‐8,10‐dodecadienol. However, once activated by a pheromone stimulus, males no longer distinguish between a pheromone source and these antagonistic blend sources. This shows that the pheromone stimulus required for the initiation of an upwind flight response differs from the stimulus for maintaining upwind flight and landing at the source. In contrast to pheromone antagonists, males discriminate between pheromone alone and a blend source of pheromone and the plant volatile pear ester, ethyl (2E,4Z)‐2,4‐decadienoate. This indicates a difference in the detection and neural integration of pheromone and plant volatile stimuli.  相似文献   
9.
10.
Carotenoids are fat-soluble pigments synthesised by photosynthetic organisms(Brush,1990).Conversely,animals are incapable of synthesizing carotenoids de novo,and they must obtain them through their diet.However,some animal species are able to make some alterations to the basic chemical structure,converting ingested carotenoids into more oxidized and differently coloured forms(Schiedt,1998).  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