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   2768980篇
  免费   211064篇
  国内免费   4605篇
耳鼻咽喉   39474篇
儿科学   85555篇
妇产科学   71890篇
基础医学   406933篇
口腔科学   76904篇
临床医学   253241篇
内科学   532515篇
皮肤病学   56926篇
神经病学   223774篇
特种医学   110264篇
外国民族医学   933篇
外科学   418416篇
综合类   61486篇
现状与发展   3篇
一般理论   1060篇
预防医学   220650篇
眼科学   64492篇
药学   209234篇
  5篇
中国医学   5169篇
肿瘤学   145725篇
  2018年   28199篇
  2016年   24058篇
  2015年   27065篇
  2014年   38498篇
  2013年   58288篇
  2012年   79957篇
  2011年   85120篇
  2010年   49879篇
  2009年   47074篇
  2008年   80251篇
  2007年   85888篇
  2006年   86446篇
  2005年   84014篇
  2004年   81048篇
  2003年   78312篇
  2002年   77194篇
  2001年   126265篇
  2000年   130621篇
  1999年   110163篇
  1998年   31587篇
  1997年   28465篇
  1996年   28323篇
  1995年   27290篇
  1994年   25622篇
  1993年   24044篇
  1992年   89030篇
  1991年   87820篇
  1990年   85319篇
  1989年   82404篇
  1988年   76613篇
  1987年   75521篇
  1986年   71260篇
  1985年   68081篇
  1984年   51324篇
  1983年   43726篇
  1982年   26001篇
  1981年   23215篇
  1980年   21821篇
  1979年   48360篇
  1978年   34061篇
  1977年   28342篇
  1976年   27301篇
  1975年   29401篇
  1974年   35754篇
  1973年   33910篇
  1972年   31761篇
  1971年   29419篇
  1970年   27681篇
  1969年   25663篇
  1968年   23511篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
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   
52.
53.
54.
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   
55.
56.
Endoscopic clips have been used mainly for control of gastrointestinal (GI) bleeding and occasionally for closure of GI perforations. However, closure of spontaneous esophageal perforation (Boerhaave's syndrome) by clipping has not been reported. We described successful non-surgical closure of spontaneous esophageal perforation by endoscopic clipping in a patient with bilateral pyopneumothorax and septicemia.  相似文献   
57.
58.
59.
60.
CONTEXT: Although the nonmedical use of stimulant drugs such as cocaine and methamphetamine is increasingly common in many rural areas of the United States, little is known about the health beliefs of people who use these drugs. PURPOSE: This research describes illicit stimulant drug users' views on health and health-related concepts that may affect their utilization of health care services. METHODS: A respondent-driven sampling plan was used to recruit 249 not-in-treatment, nonmedical stimulant drug users who were residing in 3 rural counties in west central Ohio. A structured questionnaire administered by trained interviewers was used to collect information on a range of topics, including current drug use, self-reported health status, perceived need for substance abuse treatment, and beliefs about health and health services. FINDINGS: Participants reported using a wide variety of drugs nonmedically, some by injection. Alcohol and marijuana were the most commonly used drugs in the 30 days prior to the interview. Powder cocaine was used by 72.3% of the sample, crack by 68.3%, and methamphetamine by 29.7%. Fair or poor health status was reported by 41.3% of the participants. Only 20.9% of the sample felt they needed drug abuse treatment. Less than one third of the sample reported that they would feel comfortable talking to a physician about their drug use, and 65.1% said they preferred taking care of their problems without getting professional help. CONCLUSIONS: Stimulant drug users in rural Ohio are involved with a range of substances and hold health beliefs that may impede health services utilization.  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