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   1475781篇
  免费   116859篇
  国内免费   3494篇
耳鼻咽喉   19243篇
儿科学   47995篇
妇产科学   42298篇
基础医学   209294篇
口腔科学   40282篇
临床医学   131031篇
内科学   300036篇
皮肤病学   34880篇
神经病学   122672篇
特种医学   55320篇
外国民族医学   466篇
外科学   219263篇
综合类   33028篇
现状与发展   3篇
一般理论   509篇
预防医学   115865篇
眼科学   32796篇
药学   102887篇
  1篇
中国医学   3581篇
肿瘤学   84684篇
  2021年   11955篇
  2019年   12815篇
  2018年   18718篇
  2017年   13954篇
  2016年   15556篇
  2015年   17924篇
  2014年   24515篇
  2013年   36307篇
  2012年   50990篇
  2011年   53513篇
  2010年   30785篇
  2009年   28923篇
  2008年   49151篇
  2007年   51746篇
  2006年   52487篇
  2005年   50746篇
  2004年   48143篇
  2003年   45687篇
  2002年   43969篇
  2001年   74021篇
  2000年   75828篇
  1999年   62268篇
  1998年   17196篇
  1997年   15575篇
  1996年   15729篇
  1995年   14934篇
  1994年   13493篇
  1993年   12687篇
  1992年   45996篇
  1991年   43622篇
  1990年   41591篇
  1989年   39655篇
  1988年   36253篇
  1987年   35424篇
  1986年   32949篇
  1985年   31366篇
  1984年   23934篇
  1983年   20092篇
  1982年   12295篇
  1981年   10846篇
  1979年   20753篇
  1978年   14624篇
  1977年   12124篇
  1976年   11414篇
  1975年   11649篇
  1974年   14027篇
  1973年   13574篇
  1972年   12652篇
  1971年   11501篇
  1970年   10935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