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   1975257篇
  免费   149317篇
  国内免费   4297篇
耳鼻咽喉   26067篇
儿科学   64987篇
妇产科学   54672篇
基础医学   289877篇
口腔科学   54255篇
临床医学   178247篇
内科学   387411篇
皮肤病学   45903篇
神经病学   154892篇
特种医学   74273篇
外国民族医学   531篇
外科学   294159篇
综合类   44732篇
现状与发展   5篇
一般理论   618篇
预防医学   151933篇
眼科学   45180篇
药学   142875篇
  3篇
中国医学   5270篇
肿瘤学   112981篇
  2019年   15720篇
  2018年   22408篇
  2017年   17094篇
  2016年   19369篇
  2015年   21567篇
  2014年   30254篇
  2013年   45042篇
  2012年   60725篇
  2011年   64390篇
  2010年   37965篇
  2009年   36144篇
  2008年   59572篇
  2007年   63341篇
  2006年   64326篇
  2005年   61672篇
  2004年   59435篇
  2003年   56478篇
  2002年   54671篇
  2001年   99834篇
  2000年   101950篇
  1999年   84377篇
  1998年   23175篇
  1997年   20585篇
  1996年   20825篇
  1995年   19795篇
  1994年   18014篇
  1993年   16853篇
  1992年   63963篇
  1991年   61771篇
  1990年   59638篇
  1989年   57502篇
  1988年   52530篇
  1987年   51245篇
  1986年   48182篇
  1985年   45692篇
  1984年   34366篇
  1983年   28963篇
  1982年   17130篇
  1981年   15171篇
  1979年   30516篇
  1978年   21468篇
  1977年   17965篇
  1976年   17098篇
  1975年   18069篇
  1974年   21453篇
  1973年   20670篇
  1972年   19384篇
  1971年   17745篇
  1970年   16947篇
  1969年   15602篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
73.
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   
74.
75.
OBJECTIVE: Antidepressants are commonly used drugs with potential for numerous drug interactions. This study aims to systematically review the literature on drug interactions with antidepressants. METHODS: We searched MEDLINE (1966 to November 2003) and EMBASE (1980 to 2003), using the heading drug interactions combined with individual antidepressant names. We restricted searches to English-language articles and human studies. We screened drug interaction texts and review articles for relevant studies. We included articles reporting original human data on drug interactions with antidepressants commonly used in North America. Articles were independently evaluated by 2 reviewers on clinical effect, clinical significance, and quality of evidence. Discrepancies were resolved by consensus. RESULTS: There were 904 eligible interactions, involving 9509 patients, for a total of 598 summary interactions. Of these, 439 (73%) demonstrated an interaction, 148 (25%) had no effect, and 11 (2%) had conflicting evidence. For 510 interactions (85%), the quality of evidence was poor. It was fair for 67 (11%) interactions and good for 10 (2%) interactions. There were no interactions with excellent quality of evidence. There were 145 (24%) interactions of major clinical significance. These were predominantly hypertensive emergencies and serotonin syndrome. Most interacting drugs had central nervous system (CNS) activity. As expected, monoamine oxidase inhibitors (MAOIs) appear to be the most problematic family in terms of potential for serious drug interactions. CONCLUSIONS: Drug interactions with antidepressants are an important cause for concern, but this concern is based primarily on poor evidence. We recommend caution when combining antidepressants with other CNS drugs, particularly when coadministering MAOIs with other substances.  相似文献   
76.
77.
78.
79.
Preventing unintended pregnancies through access to modern family planning could avert 20-35% of maternal deaths, saving the lives of more than 100,000 women each year. Obstacles to wider access still exist, but they may be overcome by overt policy commitment to reproductive health services, partnership between stakeholders, community involvement and quality programs.  相似文献   
80.
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