全文获取类型
收费全文 | 453篇 |
免费 | 8篇 |
专业分类
461篇 |
出版年
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 13篇 |
2012年 | 20篇 |
2011年 | 20篇 |
2010年 | 22篇 |
2009年 | 24篇 |
2008年 | 10篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 4篇 |
2004年 | 8篇 |
1999年 | 5篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1972年 | 9篇 |
1971年 | 11篇 |
1969年 | 4篇 |
1965年 | 4篇 |
1959年 | 6篇 |
1958年 | 4篇 |
1956年 | 3篇 |
1954年 | 5篇 |
1953年 | 3篇 |
1952年 | 4篇 |
1951年 | 4篇 |
1950年 | 4篇 |
1929年 | 3篇 |
排序方式: 共有461条查询结果,搜索用时 0 毫秒
51.
52.
The Ovule and 'Seed' of Araucaria Bidwilli with Discussion of the Taxonomy of the Genus II. Taxonomy
This paper deals with the taxonomic and historical backgroundof the genus Araucaria with a discussion and evaluation of charactersused as a basis for sectional division. The three existing sectionsare more clearly delimited and a new section-Sectio Bunya-isproposed for A. Bidwilli, which is removed from section Columbea.A key to the four sections is given. 相似文献
53.
54.
55.
56.
57.
58.
ABSTRACT. The circadian locomotor (walking) rhythms of individual forager honeybees ( Apis mellifera ligustica L.) were measured under a variety of conditions. In constant dark the rhythms exhibited endogenous periodicities that were less than 24 h, whereas under constant light the periods tended to be greater than 24 h. Individual honeybees readily entrained to photoperiods, displaying a diurnal pattern of entrainment with most of the activity occurring in late photophase. Evidence is presented which suggests that foraging behaviour and general locomotor behaviour may be governed by two different circadian clock systems. 相似文献
59.
The posterior oesophagus of N. reticulatus (Linnaeus) consistsof two histologically distinct regions. The epithelium of thethickened segment in the visceral haemocoel is virtually uniform.The cells are lipid-rich and can take up lipid from food. Inaddition, enzyme histochemistry indicates a capacity for theuptake of sugars and amino acids. The basal plasmalemma is elaboratelyinfolded and associated with numerous elongate mitochondria,features indicating an active ion pump. The physiological roleof this pump is unknown. (Received 26 March 1985; accepted 10 May 1985) 相似文献
60.
ELISABETH RUNGGER-BRÄNDLE WERNER W. FRANKE MARY OSBORN KLAUS WEBER 《Differentiation; research in biological diversity》1978,10(1-3):187-191
Tubulin-containing structures of the male germ cells of Drosophila hydei crossreact in indirect immu-nofluorescence microscopy with antibody directed against homogeneous porcine brain tubulin. There is no detectable difference in reactivity between germ cells of wildtype flies and the mutant l(3)pl (lethal-polyploid) which is characterized by microtubular abnormalities. However, the technique of indirect immunofluorescence microscopy allows the direct visualization of several abnormalities in the arrangement of the microtubular system of the mutant, particularly in the axonemal complex. 相似文献