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   2378822篇
  免费   195295篇
  国内免费   4223篇
耳鼻咽喉   34324篇
儿科学   72853篇
妇产科学   63026篇
基础医学   335675篇
口腔科学   67644篇
临床医学   215865篇
内科学   469175篇
皮肤病学   48013篇
神经病学   201215篇
特种医学   96095篇
外国民族医学   886篇
外科学   360813篇
综合类   56235篇
现状与发展   1篇
一般理论   977篇
预防医学   190987篇
眼科学   55557篇
药学   178046篇
  4篇
中国医学   4393篇
肿瘤学   126556篇
  2018年   24414篇
  2016年   20785篇
  2015年   23451篇
  2014年   33756篇
  2013年   51245篇
  2012年   69196篇
  2011年   72796篇
  2010年   42794篇
  2009年   41007篇
  2008年   68853篇
  2007年   73193篇
  2006年   74077篇
  2005年   72087篇
  2004年   69362篇
  2003年   67042篇
  2002年   66277篇
  2001年   112489篇
  2000年   116561篇
  1999年   98361篇
  1998年   27884篇
  1997年   25546篇
  1996年   25469篇
  1995年   24638篇
  1994年   23186篇
  1993年   21567篇
  1992年   79408篇
  1991年   76409篇
  1990年   73597篇
  1989年   70862篇
  1988年   65867篇
  1987年   64813篇
  1986年   61344篇
  1985年   58420篇
  1984年   44245篇
  1983年   37681篇
  1982年   22916篇
  1981年   20353篇
  1980年   19050篇
  1979年   41318篇
  1978年   29004篇
  1977年   24360篇
  1976年   22844篇
  1975年   23980篇
  1974年   29650篇
  1973年   28054篇
  1972年   26233篇
  1971年   24163篇
  1970年   22762篇
  1969年   21095篇
  1968年   19147篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
    
Ohne Zusammenfassung
Endpunkt- und Verlaufsmessungen bei entzündlichen rheumatischen Erkrankungen in Studien und Praxis
  相似文献   
43.
OBJECTIVE: To explore the impact of timing and type of ultrasound, particularly three-dimensional (3D), exposure on maternal-fetal attachment and maternal health behavior during pregnancy. METHODS: Subjects were 68 women aged 18 years or older expecting their first child who presented for a routine ultrasound scan at around either 12 or 18 weeks' gestation in Nepean Hospital, Western Sydney. Women completed questionnaires assessing maternal-fetal attachment and health behavior, and were then allocated arbitrarily to either two-dimensional (2D) or 3D ultrasound examination. Repeat questionnaires were completed 1 week later. RESULTS: Maternal-fetal attachment increased after both 2D and 3D ultrasound exposure, and the effect was moderated by the timing of exposure, with women receiving their first ultrasound examination at around 12 weeks showing the greatest change. Alcohol consumption was the only behavior to show significant change following ultrasound exposure, with a reduction in the reported average number of drinks per week. There was no significant difference in the pattern of change for 2D compared with 3D ultrasound exposure, and no effect of ultrasound exposure on maternal perception of the fetus. CONCLUSIONS: Ultrasound has a positive impact on maternal-fetal attachment, particularly in the first trimester. 3D ultrasound did not offer enhanced benefits. Associations between ultrasound exposure and alcohol consumption warrant further investigation. Larger samples are needed to clarify the moderating effects of gestational age and type of ultrasound exposure.  相似文献   
44.
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   
45.
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   
46.
47.
48.
49.
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   
50.
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