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   2069695篇
  免费   165572篇
  国内免费   4799篇
耳鼻咽喉   28889篇
儿科学   65722篇
妇产科学   60118篇
基础医学   295567篇
口腔科学   58065篇
临床医学   184326篇
内科学   405176篇
皮肤病学   46552篇
神经病学   170777篇
特种医学   80558篇
外国民族医学   626篇
外科学   313866篇
综合类   52378篇
现状与发展   4篇
一般理论   704篇
预防医学   162982篇
眼科学   48207篇
药学   148755篇
  1篇
中国医学   4464篇
肿瘤学   112329篇
  2018年   21878篇
  2017年   16795篇
  2016年   19023篇
  2015年   21588篇
  2014年   30680篇
  2013年   46181篇
  2012年   62416篇
  2011年   65864篇
  2010年   38670篇
  2009年   36866篇
  2008年   61324篇
  2007年   65488篇
  2006年   65927篇
  2005年   64083篇
  2004年   61699篇
  2003年   59177篇
  2002年   57143篇
  2001年   96826篇
  2000年   99118篇
  1999年   82836篇
  1998年   24083篇
  1997年   21808篇
  1996年   21749篇
  1995年   20646篇
  1994年   19082篇
  1993年   17893篇
  1992年   64783篇
  1991年   62341篇
  1990年   60290篇
  1989年   57635篇
  1988年   53471篇
  1987年   52343篇
  1986年   49294篇
  1985年   47301篇
  1984年   36321篇
  1983年   30804篇
  1982年   19193篇
  1981年   17330篇
  1979年   34083篇
  1978年   24267篇
  1977年   20271篇
  1976年   18915篇
  1975年   19854篇
  1974年   24354篇
  1973年   23470篇
  1972年   22189篇
  1971年   20351篇
  1970年   19401篇
  1969年   18370篇
  1968年   16953篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The increased number of lymphocytes in airways during an asthmatic response is believed to be the result of increased recruitment of these cells. However, it is possible that a decreased apoptotic rate could also contribute to the increased number. The aim of the present study was to investigate whether allergen airway provocation influences the apoptotic phenotype of lung and peripheral blood lymphocytes (PBL) in subjects with atopic asthma. Bronchoalveolar lavage (BAL) lymphocytes and PBL from 12 asthmatic subjects previously challenged with allergen (n = 7) or saline (n = 5) were exposed to the apoptotic stimulus tributyltin (TBT) in vitro and assayed for apoptosis. Airway allergen provocation resulted in decreased sensitivity of BAL lymphocytes to TBT-induced apoptosis, with 42.2% (range 33.9-62.5%) apoptotic cells before challenge versus 23.5% (range 15.3-42.4%) after challenge, while PBL were unaffected. The increased apoptosis resistance correlated with higher numbers of Bcl-2-expressing lymphocytes. Interestingly, baseline caspase-3-like activity was significantly elevated in viable BAL lymphocytes compared with viable PBL, and was unaltered by allergen exposure. In conclusion, allergen inhalation renders bronchoalveolar lavage lymphocytes more resistant to apoptosis while peripheral blood lymphocytes were not influenced at all, indicating that the apoptotic phenotype of airway lymphocytes may play a role in asthmatic inflammation.  相似文献   
32.
33.
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   
34.
35.
36.
37.
38.
39.
40.
Cutaneous plasmacytosis is a rare disorder characterized by a benign proliferation of mature plasma cells that appears as multiple dark-brown to purplish skin lesions, often associated with polyclonal hypergammaglobulinaemia. We present the case of a 55-year-old Caucasian man who suffered from a cutaneous plasmacytosis associated with two different carcinomas. Cutaneous plasmacytosis seems to be a reactive process because most cases reported are not associated with any apparent underlying disease. Nevertheless, because few reported cases were associated with malignancies, screening of additional neoplasms would be justified.  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