全文获取类型
收费全文 | 509篇 |
免费 | 21篇 |
国内免费 | 1篇 |
出版年
2014年 | 7篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 15篇 |
2010年 | 38篇 |
2009年 | 24篇 |
2008年 | 19篇 |
2007年 | 29篇 |
2006年 | 23篇 |
2005年 | 15篇 |
2004年 | 5篇 |
2002年 | 5篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1987年 | 7篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1980年 | 10篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 8篇 |
1972年 | 11篇 |
1971年 | 10篇 |
1968年 | 6篇 |
1966年 | 4篇 |
1959年 | 8篇 |
1957年 | 7篇 |
1956年 | 8篇 |
1955年 | 9篇 |
1954年 | 7篇 |
1953年 | 8篇 |
1952年 | 4篇 |
1951年 | 4篇 |
1950年 | 9篇 |
1949年 | 4篇 |
1948年 | 6篇 |
1941年 | 5篇 |
排序方式: 共有531条查询结果,搜索用时 171 毫秒
141.
FRANK WUNDERLICH HELLA STÜBIG EBERHARD K
NIGK 《The Journal of eukaryotic microbiology》1982,29(1):49-59
Thin-sectioning and freeze-etching electron microscopy were applied to explore the structure and the temperature- and Ca2+-response of the different host and parasite membranes during intraerythrocytic development of Plasmodium knowlesi in Macacca mulatta. The plasma membrane of uninfected erythrocytes is temperature- and Ca2+-responsive: chilling to 4°C and exposure to 5 mM Ca2+ induces a slight decrease in IMP-frequency and the emergence of small IMP-devoid patches on P-faces. On parasite infection, the erythrocyte membrane becomes modified as indicated by an enhanced temperature-response and the appearance of caveolae, ca. 70–90 nm in diameter. The frequency of these caveolae is increased in schizont-infected erythrocytes. Moreover, electron dense plaques, ca. 40 nm in width, appear just beneath the erythrocyte membrane in late trophozoites and schizonts, thus indicating a further modification of the host cell membrane during parasite development. The membrane of the parasitophorous vacuole, derived from the host plasma membrane, dramatically reduces the IMP-frequency especially on the P-face upon parasite infection. This leads to an apparent reversal of the IMP-distribution persisting throughout the whole infection cycle. The parasite plasma membrane forms local compaction domains with the nuclear envelope in ca. 30% of the ring-stages and trophozoites, which disappear in late trophozoites and schizonts. Moreover, the IMP-frequency on plasma membrane fracture faces almost doubles during parasite development. Chilling induces a decrease in the IMP-frequency on P-faces of the plasma membrane. Surprisingly, however, the parasite plasma membrane and the vacuolar membrane respond to externally applied Ca2+ with almost a doubling of the IMP-frequency. The different parasite endomembranes also undergo characteristic changes during parasite development. 相似文献
142.
Homologies of the forewing venation pattern of the order Mantodea (Insecta: Dictyoptera) consistent with the accepted insect wing venation groundplan are proposed. A comparative morphological analysis was carried out based on a broad taxonomic sample of extant taxa. Besides macromorphological aspects, focus is given to the pattern of the tracheal system as a basis for establishing primary homologies. All extant praying mantids exhibit a composite stem composed of the posterior radius (RP) and the media (M) and most praying mantids exhibit a fusion of the anterior branch of RP + M with the anterior radius (RA). The wing venation of the species ?Mesoptilus dolloi, previously assigned to the polyphyletic fossil assemblage ‘Protorthoptera’, is re‐interpreted in the light of the new homology statement. Our interpretation suggests that it is a putative stem‐Mantodea, as are some other ‘protorthopterous’ taxa. This hypothesis implies that the total‐group Mantodea arose as soon as the Late Carboniferous, i.e. about 175 million years earlier than previously estimated. This analysis contributes to the view that most of the Late Carboniferous ‘Protorthoptera’ are stem‐representatives of the major polyneopteran clades (e.g. cockroaches, grasshoppers and crickets, rock‐crawlers), suggesting a survivorship of several main Pterygota lineages at the end‐Permian extinction event higher than previously expected. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 79–113. 相似文献
143.
144.
FRANK GLAW MIGUEL VENCES FRANCO ANDREONE DENIS VALLAN 《Zoological Journal of the Linnean Society》2001,133(4):495-529
A systematic revision of the Malagasy frogs hitherto attributed to the Boophis difficilis group is presented. The difficilis holotype is not conspecific with other specimens hitherto named Boophis difficilis but belongs to the B. tephraeomystax group based on lack of webbing between fingers and the presence of heterogeneously granular ventral skin. Rhacophorus difficilis Boettger, 1892 is considered as junior synonym of Boophis tephraeomystax. The Boophis difficilis group is dissolved and its species are transferred to a new species group named after Boophis majori , the oldest of the included taxa. All species of the B. majori group, their type specimens, and their geographical distributions are revised based on new morphological, bioacoustic and ecological data. Five new species of the group from the eastern rainforests of Madagascar are described. Morphological differentiation within the B. majori group is low, although some species can be distinguished by characters such as snout-vent length, relative tympanum size, or coloration. The most reliable character for species identification are advertisement calls which are strikingly different between most species of the group. Species diversity in Boophis is highest in central eastern Madagascar and gets lower at the northern and southern borders of the island. Available data do not allow a comprehensive phylogenetic analysis of the B. majori group, but a northern subgroup of small species without red coloration and a southern subgroup of larger species with distinct red pigments can be distinguished. Osteological data for B. miniatus are provided. Within Boophis , representatives of all species groups except the B. tephraeomystax group are characterized by a synapomorphic reduction of the anterolateral hyoidal process. 相似文献
145.
146.
147.
148.
149.
150.