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   2502303篇
  免费   220771篇
  国内免费   6137篇
耳鼻咽喉   38434篇
儿科学   77415篇
妇产科学   64994篇
基础医学   337927篇
口腔科学   69083篇
临床医学   238448篇
内科学   507647篇
皮肤病学   54806篇
神经病学   213227篇
特种医学   101090篇
外国民族医学   886篇
外科学   394399篇
综合类   56442篇
现状与发展   73篇
一般理论   978篇
预防医学   196729篇
眼科学   58365篇
药学   178580篇
  4篇
中国医学   4399篇
肿瘤学   135285篇
  2018年   30411篇
  2017年   24981篇
  2016年   27543篇
  2015年   30342篇
  2014年   46656篇
  2013年   64056篇
  2012年   73487篇
  2011年   77115篇
  2010年   51300篇
  2009年   52956篇
  2008年   73781篇
  2007年   76682篇
  2006年   79658篇
  2005年   75287篇
  2004年   71981篇
  2003年   68762篇
  2002年   68029篇
  2001年   115708篇
  2000年   119118篇
  1999年   101041篇
  1998年   30849篇
  1997年   28306篇
  1996年   28049篇
  1995年   27148篇
  1994年   24685篇
  1993年   22744篇
  1992年   80469篇
  1991年   77502篇
  1990年   74422篇
  1989年   71786篇
  1988年   66666篇
  1987年   65497篇
  1986年   62052篇
  1985年   58993篇
  1984年   44656篇
  1983年   38051篇
  1982年   23256篇
  1981年   20654篇
  1980年   19321篇
  1979年   41529篇
  1978年   29239篇
  1977年   24674篇
  1976年   23023篇
  1975年   24178篇
  1974年   29811篇
  1973年   28218篇
  1972年   26471篇
  1971年   24309篇
  1970年   22942篇
  1969年   21157篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  相似文献   
52.
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   
53.
54.
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