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   503篇
  免费   36篇
耳鼻咽喉   10篇
儿科学   11篇
妇产科学   53篇
基础医学   72篇
口腔科学   16篇
临床医学   39篇
内科学   84篇
皮肤病学   21篇
神经病学   41篇
特种医学   4篇
外科学   53篇
综合类   8篇
预防医学   52篇
眼科学   47篇
药学   24篇
肿瘤学   4篇
  2023年   4篇
  2022年   4篇
  2021年   14篇
  2020年   6篇
  2019年   10篇
  2018年   6篇
  2017年   7篇
  2016年   8篇
  2015年   5篇
  2014年   18篇
  2013年   19篇
  2012年   22篇
  2011年   26篇
  2010年   8篇
  2009年   11篇
  2008年   28篇
  2007年   24篇
  2006年   21篇
  2005年   18篇
  2004年   21篇
  2003年   23篇
  2002年   14篇
  2001年   10篇
  2000年   11篇
  1999年   12篇
  1998年   4篇
  1997年   4篇
  1995年   4篇
  1994年   7篇
  1992年   13篇
  1991年   12篇
  1990年   9篇
  1989年   9篇
  1988年   11篇
  1987年   8篇
  1986年   10篇
  1985年   14篇
  1983年   5篇
  1982年   3篇
  1981年   5篇
  1980年   5篇
  1979年   11篇
  1978年   12篇
  1977年   4篇
  1976年   3篇
  1974年   2篇
  1973年   6篇
  1972年   4篇
  1971年   3篇
  1970年   6篇
排序方式: 共有539条查询结果,搜索用时 15 毫秒
81.
The incidence of lethal, serious and trivial malformations was determined in a consecutive series of 675 infants who weightd 1500 g or less (very low birth weight infants). All patients were born in one maternity hospital. Most of the 169 survivors were followed until at least five years of age. Of these children, 15 had a trivial malformation that either disappeared spontaneously or was corrected surgically. A further five children have a significant or serious residual defect. There were 506 perinatal and infant deaths and 51 of the babies who died had malformations confirmed at necropsy. In 30 of these, death was inevitable. There were 10 seriously malformed infants for whom survival was possible, but in six cases, the diagnosis was obvious at birth. The patients were treated between 1966 and 1970 when techniques of intensive care were evolving. Consequently, some of the infants who died would have survived with the treatment now available. Amongst the perinatal deaths in this report, only 2.0% had a serious malformation compatible with survival.  相似文献   
82.
Many patients are admitted to emergency facilities without positive identification. In the past, these patients were usually assigned a temporary alias name (i.e., John Doe, Jane Doe) which was then changed after positive identification. We have discerned several problems with this procedure and have subsequently developed a coordinated system of alias identification in our hospital. This system allows for: a large pool of distinct alias identities, pre-assignment of hospital numbers to unidentified patients before arrival, and a smooth administrative transition as records are changed from the alias to the true identity.  相似文献   
83.
84.
85.
86.
87.
88.
89.
PURPOSE: To document the existence of idiopathic bilateral optic atrophy (BOA) in rhesus macaque monkeys and to characterize the structural and functional consequences of this condition. METHODS: In vivo assessment of retinal and optic nerve structure included fundus biomicroscopy and stereophotography. Functional analyses included transient pattern-reversal electroretinography (PERG) and full-field flash ERG, with both white flashes while dark adapted and red flashes on a blue background used to assess the photopic negative response (PhNR). Also measured were visual evoked cortical potentials (VEPs) and multifocal (mf)ERGs, with both a standard fast and slowed (7F) stimulation sequence. Post mortem histologic evaluation was performed on a subset of five animals with BOA and compared with data from 22 healthy normal animals. Blood tests, including vitamin E, B(12), folate, lead, and complete blood cell count with differential were obtained on the four animals that remained alive. RESULTS: Animals with BOA showed temporal pallor of the optic nerve head and thinning of the retinal nerve fiber layer (RNFL) between the temporal vascular arcades (i.e., of the papillomacular bundle). Severity of optic atrophy and RNFL loss varied between animals from mild to severe, but was similar in the two eyes of each animal. Functional changes included greater loss of the PERG N95, compared with the P50 component and substantial reduction of mfERG high-frequency components. The mfERG low-frequency components were slightly larger than normal. None of the full-field flash ERG amplitudes (a-wave, b-wave, oscillatory potentials, or PhNR) was significantly different from normal. There were no consistent abnormalities found in the results of any blood test. Histologic findings included axonal loss and gliosis limited to the temporal optic nerve, reduction of nuclei within the retinal ganglion cell layer, and thinning of the temporal retinal RNFL. CONCLUSIONS: The existence of BOA in nonhuman primates warrants caution on the part of investigators who use these animals in experimental models of ophthalmic disease.  相似文献   
90.
The utility of plasmid DNA as an immunogen has been limited by its weak immunogenicity. In the present study, we evaluated the ability of a family of linear polyethylenimine (PEI) polymers, complexed to plasmid DNA, to augment DNA expression in vivo and to enhance antigen‐specific adaptive immune responses. We showed that four of five structurally different PEIs that we evaluated increased in vivo DNA expression 20‐ to 400‐fold, and enhanced DNA‐induced epitope‐specific CD8+ T‐cell responses 10‐ to 25‐fold in BALB/c and C57BL/6J mice respectively, when delivered intravenously. Functional studies of the PEI‐DNA‐induced CD8+ T‐cell responses demonstrated that formulation of DNA with PEI was associated with increased numbers of cells secreting type I cytokines. In addition, PEI‐DNA complexes improved antigen‐specific TH1‐helper cell and humoral responses. Most importantly, the PEI‐DNA complexes elicited memory cellular responses, capable of rapid expansion and accelerated clearance of a lethal dose of recombinant Listeria monocytogenes. Lastly, we identified physical properties of PEI‐DNA complexes that are associated with enhanced DNA‐elicited immunogenicity. These findings demonstrate that PEI polymers can play an important role in the development of DNA‐based vaccines in the setting of infectious disease prevention and cancer therapy.  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