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   2397916篇
  免费   181700篇
  国内免费   4878篇
耳鼻咽喉   33447篇
儿科学   79716篇
妇产科学   69171篇
基础医学   345530篇
口腔科学   66623篇
临床医学   211869篇
内科学   470443篇
皮肤病学   53711篇
神经病学   192185篇
特种医学   92220篇
外国民族医学   793篇
外科学   363693篇
综合类   54127篇
现状与发展   4篇
一般理论   743篇
预防医学   184769篇
眼科学   55108篇
药学   175610篇
  2篇
中国医学   5205篇
肿瘤学   129525篇
  2018年   25273篇
  2017年   19207篇
  2016年   21737篇
  2015年   24629篇
  2014年   34508篇
  2013年   51814篇
  2012年   70565篇
  2011年   75202篇
  2010年   44402篇
  2009年   42109篇
  2008年   70855篇
  2007年   75768篇
  2006年   76747篇
  2005年   74704篇
  2004年   71812篇
  2003年   68873篇
  2002年   67272篇
  2001年   113244篇
  2000年   115956篇
  1999年   97392篇
  1998年   27842篇
  1997年   25074篇
  1996年   25187篇
  1995年   23896篇
  1994年   21995篇
  1993年   20673篇
  1992年   75849篇
  1991年   73511篇
  1990年   71644篇
  1989年   69084篇
  1988年   63768篇
  1987年   62530篇
  1986年   59005篇
  1985年   56327篇
  1984年   42521篇
  1983年   36494篇
  1982年   21962篇
  1981年   19531篇
  1979年   38934篇
  1978年   27578篇
  1977年   23282篇
  1976年   22125篇
  1975年   23601篇
  1974年   28094篇
  1973年   27081篇
  1972年   25584篇
  1971年   23538篇
  1970年   22167篇
  1969年   20984篇
  1968年   19725篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a rare malignant tumour of the skin, with an estimated incidence of 0.8 to five cases per 1 million people per year. OBJECTIVE: To study epidemiological, immunohistochemical and clinical features, delay in diagnosis, type of treatment and outcome of DFSP from 1982 to 2002. METHODS: Using data from the population-based cancer registry, 66 patients with pathologically proved DFSP were included (fibrosarcomatous DFSP were excluded). Each patient lived in one of the four departments of Franche-Comté (overall population of 1 million people) at the time of diagnosis. The main data sources came from public and private pathology laboratories and medical records. The rules of the International Agency for Research on Cancer were applied. RESULTS: The estimated incidence of DFSP in Franche-Comté was about three new cases per 1 million people per year. Male patients were affected 1.2 times as often as female patients were. The trunk (45%) followed by the proximal extremities (38%) were the most frequent locations. DFSP occurred mainly in young adults between 20 and 39 years of age. Mean age at diagnosis was 43 years, and the mean delay in diagnosis was 10.08 years. Our 66 patients initially underwent a radical local excision. Among them, 27% experienced one or more local recurrences during 9.6 years of follow-up. There was one regional lymph node recurrence without visceral metastases. These recurrences were significantly related to the initial peripheral resection margins. We observed a local recurrence rate of 47% for margins less than 3 cm, vs. only 7% for margins ranging from 3 to 5 cm [P=0.004; OR=0.229 (95%, CI=0.103-0.510)]. The mean time to a first local recurrence was 2.65 years. Nevertheless, there was no death due to the DFSP course at the end of the follow-up, and the final outcome was favourable. CONCLUSION: Our study emphasizes the importance of wide local excision with margins of at least 3 cm in order to prevent local recurrence. However, the recent development of inhibitors of signal transduction by the PDGFB pathway should soon modify the surgical strategy, which is often too mutilating.  相似文献   
102.
103.
A 65-year-old man developed acute limb ischemia, severe abdominal wall and lower limb livedo reticularis following a coronary angiogram. The differential diagnoses of acute limb ischemia and multiple cholesterol emboli syndrome (MCES) are discussed. This work was performed at Long Island Jewish Medical Center, 270-05, 76th Avenue, New Hyde Park, NY 11040.  相似文献   
104.
105.
106.
107.
108.
109.
110.
Previously we derived independent estimates of the effect of the dopamine D2 receptor (DRD2) Ser311Cys polymorphism on risk for schizophrenia using fixed- and random-effects meta-analyses. Both analyses identified a significant association between the Cys allele and schizophrenia, but neither included all available data. Furthermore, genotype data were not evaluated in either analysis, thus precluding any determination of the mode of inheritance. The present study was conducted to resolve discrepancies between the existing meta-analyses, and provide more comprehensive and accurate estimates of the nature and magnitude of the influence of the Ser311Cys polymorphism on risk for schizophrenia. All discrepancies between the two sets of previously meta-analyzed studies were identified and resolved to the mutual satisfaction of the authors, and the final dataset was analyzed independently by fixed- and random-effects meta-analyses. A total of 27 samples, comprising 3,707 schizophrenia patients and 5,363 control subjects, were included in the analyses of allelic association, while smaller numbers of studies and subjects were included in each of the genotypic association analyses. A significant effect of the Cys allele was observed under both fixed-effects (odds ratio [OR] = 1.4; P = 0.002) and random-effects (OR = 1.4; P = 0.007) models. Cys/Ser heterozygotes were at elevated risk for schizophrenia when compared to Ser/Ser homozygotes (fixed- and random-effects OR = 1.4, p(s) or= 0.948). There was no evidence of heterogeneity, excessive influence of any single study, or publication bias in any of the analyses, suggesting that the effect of this DRD2 polymorphism on schizophrenia risk is reliable and uniform across populations, and our estimates of its magnitude are robust and accurate.  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