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   3169790篇
  免费   262551篇
  国内免费   13824篇
耳鼻咽喉   43810篇
儿科学   100094篇
妇产科学   81626篇
基础医学   508865篇
口腔科学   84421篇
临床医学   279262篇
内科学   558126篇
皮肤病学   86080篇
神经病学   273760篇
特种医学   125903篇
外国民族医学   361篇
外科学   498149篇
综合类   96793篇
现状与发展   23篇
一般理论   2168篇
预防医学   264378篇
眼科学   71291篇
药学   214873篇
  22篇
中国医学   9234篇
肿瘤学   146926篇
  2021年   54794篇
  2020年   34961篇
  2019年   57943篇
  2018年   70357篇
  2017年   53717篇
  2016年   59298篇
  2015年   73581篇
  2014年   107659篇
  2013年   172747篇
  2012年   84917篇
  2011年   84021篇
  2010年   114533篇
  2009年   119781篇
  2008年   71780篇
  2007年   73769篇
  2006年   84751篇
  2005年   80764篇
  2004年   82563篇
  2003年   73972篇
  2002年   64002篇
  2001年   89256篇
  2000年   81848篇
  1999年   84991篇
  1998年   63486篇
  1997年   61811篇
  1996年   59532篇
  1995年   54953篇
  1994年   49154篇
  1993年   45934篇
  1992年   58564篇
  1991年   55243篇
  1990年   52413篇
  1989年   51802篇
  1988年   48346篇
  1987年   47268篇
  1986年   45311篇
  1985年   45504篇
  1984年   43097篇
  1983年   39921篇
  1982年   39852篇
  1981年   37600篇
  1980年   35567篇
  1979年   35104篇
  1978年   32166篇
  1977年   29719篇
  1976年   27289篇
  1975年   25800篇
  1974年   26285篇
  1973年   25136篇
  1972年   23662篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A total of 3,604 primary malignant tumours diagnosed histologically at the Departments of Pathology in Jordan during the period 1975-1979 were analysed. The relative frequency by age, sex and site of these tumours and age-standardised incidence rate are presented. Truncated standardised incidence rates for selected tumours were compared in Jordan and other countries. Except for the urinary bladder tumours, there is a striking resemblance between Jordan and other Middle Eastern countries in the pattern of tumour-occurrence in most sites. Skin malignancies are the dominant tumours in the general and male population, breast in female population and lymphomas in children. Noteworthy are the histologically advanced bladder cancers and the relatively young females affected by breast cancer at first diagnosis. Childhood tumours comprised 7.4% of the total cancers in the present study.  相似文献   
992.
993.
Biliopancreatic diversion is a very effective method for weight reduction. In some instances it is too effective and needs to be revised.  相似文献   
994.
995.
996.
997.
Previous studies of giant axonal neuropathy have reported clinical and pathological findings that indicate involvement of the central nervous system. We studied 3 boys with giant axonal neuropathy, who were 14 to 16 years of age, using auditory, visual, and somatosensory evoked potentials. Absence of waveforms and prolongation of peak and interwave latencies were found. Abnormalities were noted in all modalities. The auditory brainstem evoked response in particular indicated a significant increase in brainstem conduction time. These studies add clinical neurophysiological confirmation of the central nervous system involvement in this disorder and may also provide a means of quantitative evaluation of its progression.  相似文献   
998.
The simultaneous determination of cerebrospinal fluid (CSF) and plasma adenosine deaminase (ADA) activity was evaluated as a diagnostic aid in tuberculous meningitis (TBM). CSF and plasma ADA activity were determined in four groups of patients: (i) a 'no meningitis' group of 174 children investigated for possible meningitis, but found to be uninfected; (ii) an aseptic meningitis group of 40 children; (iii) a bacterial meningitis group of 31 children; and (iv) a TBM group of 27 patients (24 children and 3 adults). CSF ADA alone was determined in a further 23 children with aseptic meningitis, 19 with bacterial meningitis and 13 children and 7 adults with TBM. Both the CSF/plasma ADA ratio and the absolute CSF ADA activity were raised in TBM (mean values 0,24 and 12,61 U/I respectively) and bacterial meningitis (mean values 0,59 and 15,43 U/I respectively), but not in the aseptic meningitis group (mean values 0,06 and 2,00 U/I) or the 'no meningitis' group (mean values 0,04 and 1,51 U/I). Both values will distinguish TBM from aseptic meningitis, but do not appear to hold any marked advantages over conventional CSF criteria in the diagnosis of TBM.  相似文献   
999.
The removal of N-linked oligosaccharides by peptide-N4-[N-acetyl-beta-glucoseaminyl]asparagine amidase (previously known as aspartoglycosylamine amidohydrolase and abbreviated N-glycanase) from the surface of blood or insect-transmissible forms of Trypanosoma cruzi markedly increased the capacity of these organisms to associate with (i.e., bind and penetrate) either mouse peritoneal macrophages or rat heart myoblasts. This effect was evidenced by a significant elevation in both the percentage of infected host cells and the average number of parasites per 100 cells. Conversely, N-glycanase treatment of either host cell markedly reduced both parameters to levels significantly below those obtained with cells mock treated with medium alone. The N-glycanase effect on the parasites was inhibited by heat inactivation of the enzyme or by the presence of fetuin, an N-glycanase substrate. The enhanced capacity of N-glycanase-treated T. cruzi to engage the host cells started to subside 2 h after the treatment, indicating the reversibility of the effect. The decreased reactivity of N-glycanase-treated macrophages or myoblasts with T. cruzi suggests that N-linked oligosaccharides on these host cells are involved in the initial phase of the cell infection process. Instead, because T. cruzi interacted more effectively with host cells after treatment with N-glycanase, parasite surface N-linked oligosaccharides would seem to interfere with the association.  相似文献   
1000.
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