全文获取类型
收费全文 | 3419篇 |
免费 | 278篇 |
国内免费 | 3篇 |
出版年
2022年 | 29篇 |
2021年 | 43篇 |
2020年 | 21篇 |
2019年 | 39篇 |
2018年 | 43篇 |
2017年 | 32篇 |
2016年 | 64篇 |
2015年 | 128篇 |
2014年 | 112篇 |
2013年 | 181篇 |
2012年 | 228篇 |
2011年 | 248篇 |
2010年 | 155篇 |
2009年 | 132篇 |
2008年 | 190篇 |
2007年 | 231篇 |
2006年 | 202篇 |
2005年 | 172篇 |
2004年 | 178篇 |
2003年 | 195篇 |
2002年 | 179篇 |
2001年 | 41篇 |
2000年 | 33篇 |
1999年 | 54篇 |
1998年 | 45篇 |
1997年 | 38篇 |
1996年 | 31篇 |
1995年 | 39篇 |
1994年 | 31篇 |
1993年 | 29篇 |
1992年 | 40篇 |
1991年 | 43篇 |
1990年 | 33篇 |
1989年 | 37篇 |
1988年 | 24篇 |
1987年 | 27篇 |
1986年 | 22篇 |
1985年 | 26篇 |
1984年 | 32篇 |
1983年 | 21篇 |
1982年 | 22篇 |
1981年 | 24篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1977年 | 14篇 |
1976年 | 9篇 |
1975年 | 15篇 |
1974年 | 15篇 |
1969年 | 9篇 |
1968年 | 14篇 |
排序方式: 共有3700条查询结果,搜索用时 6 毫秒
1.
2.
Halasz Norbert; Nowycky Martha C.; Shepherd Gordon M.; Hofelt Tomas 《Chemical senses》1985,10(2):203-218
aftographic exeperiments on the localization of radiolabelednoradrenaline, dopamine and dopa, as well as immunohistochemicalstudies on hydroxylase-like activity, are summarized and comparedin both rat and turtle olfactory bulbs. Evoked field potentialstudies on effects of dopamine are also discussed. The histochemicalstudies suggest that dopaminergic periglomerular neurons arethe most significant cellular component of the catecholaminergicsystem in the olfactory bulb of both species. Scattered fluorescentcell group was also present in the internal plexiform layerand superficial granule cell layer of the turtle olfactory bulb.Other fibres, not related to intrinsic bulbar neuronal cellbodies, were also labeled, mostly in the granule cell layerbut also in the external plexiform layer. These might belongto a centrifugal catecholaminergic system from brain stem neurons.In the in vitro turtle olfactory bulb, dopamine and apomorphinedepressed the amplitude of field potentials evoked by a singlevolley in the olfactory nerve or lateral olfactory tract, andreduced the depression and latency of reponses when paired volleywere delivered. It is suggested that catecholaminergic systemsplay a key role in modulating mitral cell activity through actionsin both superficial (glomerular) and deep (granule) layers.This may involve direct actions, or other, non-catecholaminergicinterneurons. 相似文献
3.
Purification of transcription factor IIIB from HeLa cells 总被引:17,自引:0,他引:17
4.
5.
6.
Deon. C. Nel Peter G. Ryan Jeanne L. Nel Norbert T. W. Klages Rory P. Wilson Graham Robertson & Geoff N. Tuck 《Ibis》2002,144(3):E141-E154
Wandering Albatrosses Diomedea exulans are frequently killed when they attempt to scavenge baited hooks deployed by long-line fishing vessels. We studied the foraging ecology of Wandering Albatrosses breeding on Marion Island in order to assess the scale of interactions with known long-line fishing fleets. During incubation and late chick-rearing, birds foraged further away from the island, in warmer waters, and showed high spatial overlap with areas of intense tuna Thunnus spp. long-line fishing. During early chick-rearing, birds made shorter foraging trips and showed higher spatial overlap with the local Patagonian Toothfish Dissostichus eleginoides long-line fishery. Tracks of birds returning with offal from the Toothfish fishery showed a strong association with positions at which Toothfish long-lines were set and most diet samples taken during this stage contained fishery-related items. Independent of these seasonal differences, females foraged further from the islands and in warmer waters than males. Consequently, female distribution overlapped more with tuna long-line fisheries, whereas males interacted more with the Toothfish long-line fishery. These factors could lead to differences in the survival probabilities of males and females. Non-breeding birds foraged in warmer waters and showed the highest spatial overlap with tuna long-line fishing areas. The foraging distribution of Marion Island birds showed most spatial overlap with birds from the neighbouring Crozet Islands during the late chick-rearing and non-breeding periods. These areas of foraging overlap also coincided with areas of intense tuna long-line fishing south of Africa. As the population trends of Wandering Albatrosses at these two localities are very similar, it is possible that incidental mortality during the periods when these two populations show the highest spatial overlap could be driving these trends. 相似文献
7.
8.
G Jahn I Dusanter-Fourt P A Kelly L M Houdebine J Djiane 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1987,184(1):19-23
A specific homologous radioimmunoassay was developed to measure rabbit beta-casein in rabbit mammary gland with a sensitivity of 0.5 ng/ml protein. It was used to measure casein concentration during pregnancy and in organ culture of mammary gland explants. Casein was detectable in virgin mammary glands, showed a small increase during the first half of pregnancy, increased more than 20-fold between Days 21 and 27, and diminished somewhat on the first days of lactation. After 24 hr of culture, mammary gland explants had no detectable casein, but the addition of increasing concentrations of prolactin to a culture medium which contained insulin (5 micrograms/ml) and cortisol (0.5 microgram/ml) induced a regular increase in the casein content of the tissue. Casein started to increase when 10 ng/ml of prolactin was present and maximal values were achieved for 100 ng/ml of the hormone. 相似文献
9.
10.
Norbert Rieder 《Hydrobiologia》1987,145(1):175-181
A group of nine sensory setae is found on the tip of the antennula ofDaphnia magna in both sexes. Inside a seta four dendrites are situated, each with one receptor cilium. The receptor cilia extend through
a liquor space into the exterior part of the seta.
The exterior part of the liquor space is divided from the interior part by a knob-like thickening of the innermost layer of
the epicuticle, the basal bead. The basal bead narrows the liquor space and the receptor cilia. The interior part of the liquor
space is surrounded by five sheath cells, the exterior part by a thin cuticle. In the exterior part the receptor cilia branch
partly and reach a terminal pellet on the tip of the seta. The terminal pellet is a thickened part of the epicuticle. It is
permeable to several dissolved substances.
It is the exterior part of the receptor that projects over the tip of the antennula and seems to be the entire seta. During
the premoult the fifth sheath cell builds up the articulation of the seta, the fourth the basal bead, and the third the shaft
of the seta. The first sheath cell forms the cuticular sheath.
The organ seems to be a chemoreceptor, but the adequate stimulus is as yet unknown. 相似文献