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   952137篇
  免费   65684篇
  国内免费   2432篇
耳鼻咽喉   12956篇
儿科学   30865篇
妇产科学   27606篇
基础医学   133193篇
口腔科学   25196篇
临床医学   82927篇
内科学   192028篇
皮肤病学   19695篇
神经病学   76476篇
特种医学   37371篇
外国民族医学   336篇
外科学   146445篇
综合类   19590篇
一般理论   353篇
预防医学   71918篇
眼科学   20869篇
药学   67267篇
中国医学   1856篇
肿瘤学   53306篇
  2019年   7372篇
  2018年   10191篇
  2017年   8076篇
  2016年   8683篇
  2015年   9885篇
  2014年   13964篇
  2013年   21778篇
  2012年   29318篇
  2011年   31252篇
  2010年   18750篇
  2009年   17776篇
  2008年   29717篇
  2007年   31540篇
  2006年   31639篇
  2005年   31249篇
  2004年   29939篇
  2003年   28903篇
  2002年   28215篇
  2001年   41820篇
  2000年   42897篇
  1999年   36735篇
  1998年   10614篇
  1997年   9724篇
  1996年   9540篇
  1995年   8891篇
  1994年   8486篇
  1993年   7903篇
  1992年   28438篇
  1991年   27202篇
  1990年   26605篇
  1989年   25545篇
  1988年   23741篇
  1987年   23343篇
  1986年   22418篇
  1985年   21312篇
  1984年   15992篇
  1983年   13648篇
  1982年   8287篇
  1979年   14677篇
  1978年   10320篇
  1977年   8685篇
  1976年   8207篇
  1975年   9006篇
  1974年   10765篇
  1973年   10221篇
  1972年   9692篇
  1971年   8943篇
  1970年   8600篇
  1969年   8033篇
  1968年   7697篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
43.
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis.  相似文献   
44.
The purpose of this study is to determine the role of liver biopsy and outcome of patients undergoing donor evaluation for adult-to-adult right hepatic lobe living donor liver transplantation (LDLT). Records of patients presenting for a comprehensive donor evaluation between 1997 and February 2005 were reviewed. Liver biopsy was performed only in patients with risk factors for abnormal histology. Two hundred and sixty patients underwent a comprehensive donor evaluation and 116 of 260 (45%) were suitable for donation, 14 of 260 (5.4%) did not complete evaluation and 130 of 260 (50%) were rejected. Four patients underwent unsuccessful hepatectomy surgery due to discovery of intraoperative abnormalities. Between 1997 and 2001, the acceptance rate of donor candidates (63%) was higher than 2002-2005 (36%), p < 0.0001. Sixty-six of the 150 eligible patients (44%) fulfilled criteria for liver biopsy and 28 of 66 (42%) had an abnormal finding. Less than half of the patients undergoing donor evaluation were suitable donors and the donor acceptance rate has declined over time. A large proportion of the patients undergoing liver biopsy have abnormal findings. Our evaluation process failed to identify 4 of 103 who had aborted donor surgeries.  相似文献   
45.
We previously reported poorer survival among non-Hispanic blacks and Hispanics with idiopathic pulmonary fibrosis (IPF) compared to non-Hispanic whites at our center. In the current study, we hypothesized that these disparities would exist in a nationwide cohort of wait-listed patients with IPF. We performed a retrospective cohort study of 2635 patients with IPF listed for lung transplantation between 1995 and 2003 at 94 transplant centers in the United States. The age-adjusted mortality rate was higher among non-Hispanic blacks [hazard ratio (HR) = 1.24, 95% confidence interval (CI) 1.06-1.45, p = 0.009] and Hispanics (HR = 1.29, 95% CI 1.06-1.56, p = 0.01) compared to non-Hispanic whites. These findings persisted after adjustment for transplantation, medical comorbidities and socioeconomic status. Worse lung function at the time of listing appeared to explain some of these differences (HR for non-Hispanic blacks after adjustment for forced vital capacity percent predicted = 1.16, 95% CI 0.98-1.36, p = 0.09; HR for Hispanics = 1.21, 95% CI 0.99-1.48, p = 0.056). In summary, black and Hispanic patients with IPF have worse survival than whites after listing for lung transplant.  相似文献   
46.
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   
47.
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   
48.
49.
50.
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