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   2257篇
  免费   98篇
  国内免费   2篇
  2022年   30篇
  2021年   58篇
  2020年   24篇
  2019年   25篇
  2018年   34篇
  2017年   23篇
  2016年   50篇
  2015年   67篇
  2014年   79篇
  2013年   198篇
  2012年   122篇
  2011年   111篇
  2010年   115篇
  2009年   148篇
  2008年   86篇
  2007年   68篇
  2006年   70篇
  2005年   63篇
  2004年   64篇
  2003年   59篇
  2002年   58篇
  2001年   24篇
  2000年   37篇
  1999年   47篇
  1998年   46篇
  1997年   56篇
  1996年   19篇
  1995年   22篇
  1994年   15篇
  1993年   27篇
  1992年   10篇
  1989年   13篇
  1988年   16篇
  1987年   11篇
  1986年   15篇
  1985年   20篇
  1984年   13篇
  1983年   18篇
  1981年   21篇
  1980年   11篇
  1979年   17篇
  1978年   24篇
  1977年   26篇
  1976年   19篇
  1975年   18篇
  1974年   14篇
  1966年   10篇
  1964年   12篇
  1953年   11篇
  1949年   14篇
排序方式: 共有2357条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
A Search for Discrete Cholinergic Nuclei in the Human Ventral Forebrain   总被引:3,自引:1,他引:2  
Abstract: Slices cut from five frozen human brains were dissected into 2-mm cubes and assayed for choline acetyltransferase (ChAT) activity and protein content. A pattern of enrichment of ChAT activity was found ventral to the anterior commissure; this finding is consistent with the location of the enzyme in the cells of the nucleus basalis of Meynert. The region beneath the anterior commissure was the only place a discrete enrichment of activity could be found, and the precise topography of the enrichment was somewhat variable from brain to brain. The results are discussed in the light of recent knowledge concerning the source of the cortical cholinergic innervation.  相似文献   
5.
6.
7.
8.
Ohne ZusammenfassungAus der von der Deutschen Forschungsgemeinschaft eingerichteten, der Symbioseforschung dienenden Arbeitsstatte in Porto d'Ischia (Napoli).  相似文献   
9.
Summary Lacertilian species display a remarkable diversity in the organization of the neural apparatus of their pineal organ (epiphysis cerebri). The occurrence of immunoreactive S-antigen and opsin was investigated in the retina and pineal organ of adult lizards, Uromastix hardwicki. In this species, numerous retinal photoreceptors displayed S-antigen-like immunoreactivity, whereas only very few pinealocytes were labeled. Immunoreactive opsin was found neither in retinal photoreceptors nor in pinealocytes. Electron microscopy showed that all pinealocytes of Uromastix hardwicki resemble modified pineal photoreceptors. A peculiar observation is the existence of a previously undescribed membrane system in the inner segments of these cells. It is evidently derived from the rough endoplasmic reticulum but consists of smooth membranes. The modified pineal photoreceptor cells of Uromastix hardwicki were never seen to establish synaptic contacts with somata or dendrites of intrapineal neurons, which are extremely rare. Vesiclecrowned ribbons are prominent in the basal processes of the receptor cells, facing the basal lamina or establishing receptor-receptor and receptor-interstitial type synaptoid contacts. Dense-core granules (60–250 nm in diameter) speak in favor of a secretory activity of the pinealocytes. Attention is drawn to the existence of receptor-receptor and receptor-interstitial cell contacts indicating intramural cellular relationships that deserve further study.Supported by the Deutsche Forschungsgemeinschaft (Ko 758/31) and the Deutscher Akademischer Austauschdienst (Senior DAAD Research Fellowship to M.A.H.)  相似文献   
10.
Summary Immunocytochemical studies were performed to describe the characteristics of cell types and their distribution in the pars distalis of Japanese long-fingered bat, Miniopterus schreibersii fuliginosus, collected at various stages of the reproductive cycle. Six distinct cell types have been identified in the pars distalis by the unlabeled immunoperoxidase technique and by the ABC method. Growth hormone (GH) and prolactin (PRL) cells were immunostained with antisera against chicken GH and ovine PRL. The GH-immunoreactive cells were round or oval orangeophilic cells distributed throughout the pars distalis with prominent aggregation in the posterolateral region. The PRL cells were pleomorphic carminophilic cells that occurred in small groups within the central and dorsocaudal regions of the pars distalis. They were sparsely distributed in the central region of the pars distalis in the hibernating bats, but increased significantly in the pregnant and lactating bats. The adrenocorticotropic (ACTH) cells were large round or polygonal amphophilic cells in the rostroventral and ventrolateral regions of the pars distalis. The thyrotropic (TSH) cells were small rounded or polygonal and distributed mainly in the ventrolateral region of the pars distalis. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) cells were identified immunocytochemically with antisera against the specific beta subunits of ovine LH and rat FSH. There were two populations of LH and FSH cells, one aggregated in the zona tuberalis and the other scattered singly throughout the rest of the pars distalis. The aggregated cells were immunoreactive with both antisera directed to LH and FSH, while scattered cells were reactive solely with antiserum to either LH or FSH and exhibited seasonal variations. In females, the proportional volume of the pars distalis occupied by LH cells was significantly reduced during pregnancy and lactation. No evidence of involution was observed in pars distalis cells except for PRL cells in males or females during hibernation.  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