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   278篇
  免费   12篇
  国内免费   1篇
  2016年   8篇
  2015年   3篇
  2014年   7篇
  2013年   15篇
  2012年   20篇
  2011年   14篇
  2010年   23篇
  2009年   9篇
  2008年   20篇
  2007年   12篇
  2006年   13篇
  2005年   10篇
  2004年   7篇
  2003年   4篇
  2001年   3篇
  2000年   3篇
  1999年   5篇
  1997年   9篇
  1996年   9篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   6篇
  1988年   3篇
  1986年   2篇
  1985年   2篇
  1982年   2篇
  1976年   2篇
  1973年   3篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1965年   2篇
  1959年   2篇
  1958年   4篇
  1957年   4篇
  1956年   5篇
  1955年   4篇
  1954年   8篇
  1953年   1篇
  1952年   2篇
  1951年   1篇
  1950年   4篇
  1949年   2篇
  1948年   3篇
  1947年   1篇
  1936年   1篇
排序方式: 共有291条查询结果,搜索用时 562 毫秒
1.
SYNOPSIS. Structure and morphogenesis, and cytochemical data on Cochlodinium heterolobatum, a new species of unarmored dinoflagellate, were derived from living and fixed material from culture. C. heterolobatum is characterized by the torsion of the girdle which descends in a left-hand spiral 1.8 turns; the sulcus having a torsion of 0.8 turn; a sulcus loop in the epicone; a tongue-shaped lobe in the right hypocone; nucleus in the epicone; and a stigma in the left epicone. Trichocysts and behavior of the nucleus during typical and atypical divisions are described in cells from cultures of different ages. A small form with the specific characters was found. Intracellular bacteria were seen and their growth followed in individuals from cultures of different ages. A possible relationship between those bacteria and the accumulation of metabolites inside old cells is discussed.  相似文献   
2.
ABSTRACT. Three strains of Phytomonas serpens two from tomatoes, Lycopersicon esculentum one from the insect Phtia picta (Hemiptera, Coreidae), were cultivated in a chemically defined medium developed from a defined medium for cultivating insect flagellates. Besides organic growth factors required by other insect trypanosomatids this flagellate requires, serine and inositol. Glutamine stimulates growth, and, surprisingly, does not require heme.  相似文献   
3.
Potamolithus karsticus n. sp. and Potamolithus troglo-bius n.sp., two Brazilian aquatic cavesnails (Gastropoda: Hydrobiidae),are described. P. troglobius is blind and depigmented, and isthe first stygobiontic snail to be described from Brazil Additionally, specimens of Potamolithus ribeirensis Pilsbry,1911 were collected near the type locality for comparison withthe new cave species (Received 2 December 1993; accepted 20 June 1994)  相似文献   
4.
5.
6.
7.
8.
9.
ABSTRACT

The vocal repertoire of Amazona amazonica during its breeding season has been recorded from wild individuals in Santa Bárbara do Pará, Pará State, Brazil. At individual nests, we continuously recorded vocalizations and behaviour for four hours in the early morning and three hours in the late afternoon, three times a week throughout the breeding season. We identified nine vocalizations that we classified in three behavioural categories: (1) Flight call—emitted when parrots arrive in the nest area; (2) Perched contact calls—two different vocalizations, one of them related to feeding, were emitted when the pair was perched in the nest area and interacted socially between themselves or with other individuals; (3) Aggressive calls—emitted when birds were in a dangerous situation, i.e. alarm (three types of calls), agonistic contact and distress calls (two types of call). The Orange-winged Parrot is a highly social species and the complexity of its social interactions is reflected in the diversity of its vocal repertoire.  相似文献   
10.
Fifteen polymorphic microsatellite markers were isolated and characterized in two species of Bromeliaceae: Vriesea gigantea and Alcantarea imperialis. The number of alleles observed for each locus ranged from three to 16. The loci will be used for studies of the genetic structure of natural populations, reproductive biology, and evolutionary relationships among and within these genera. A cross‐amplification test in 22 taxa suggests that the markers will be useful for similar applications in numerous other bromeliad species.  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