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   3412758篇
  免费   249298篇
  国内免费   10807篇
耳鼻咽喉   45586篇
儿科学   112197篇
妇产科学   94457篇
基础医学   484041篇
口腔科学   94321篇
临床医学   320059篇
内科学   665440篇
皮肤病学   78097篇
神经病学   283146篇
特种医学   129046篇
外国民族医学   1047篇
外科学   499415篇
综合类   71992篇
现状与发展   6篇
一般理论   1343篇
预防医学   272551篇
眼科学   76555篇
药学   250044篇
  12篇
中国医学   7483篇
肿瘤学   186025篇
  2019年   27663篇
  2018年   38873篇
  2017年   29652篇
  2016年   33903篇
  2015年   38289篇
  2014年   52770篇
  2013年   80412篇
  2012年   107513篇
  2011年   113812篇
  2010年   68259篇
  2009年   64667篇
  2008年   105770篇
  2007年   111988篇
  2006年   113647篇
  2005年   109081篇
  2004年   104651篇
  2003年   100899篇
  2002年   97527篇
  2001年   159177篇
  2000年   163392篇
  1999年   137952篇
  1998年   40257篇
  1997年   35761篇
  1996年   35758篇
  1995年   34509篇
  1994年   31856篇
  1993年   29961篇
  1992年   108309篇
  1991年   104733篇
  1990年   101556篇
  1989年   97729篇
  1988年   89776篇
  1987年   88043篇
  1986年   83027篇
  1985年   79331篇
  1984年   59330篇
  1983年   50647篇
  1982年   30175篇
  1981年   26904篇
  1979年   52949篇
  1978年   37600篇
  1977年   31532篇
  1976年   29783篇
  1975年   31364篇
  1974年   37425篇
  1973年   35830篇
  1972年   33481篇
  1971年   31153篇
  1970年   28837篇
  1969年   27302篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Poor results after surgery for bronchioloalveolar carcinoma.   总被引:2,自引:0,他引:2  
BACKGROUND: Bronchioloalveolar carcinoma (BAC) is suggested to be less aggressive than other types of lung cancer. To assess the option of treatment modification, actual outcome data were studied and compared with results for other types of lung cancer. METHOD: Retrospective analysis of all consecutive patients who underwent resection for stage I lung cancer in our hospital. For 18 BAC cases, histological specimens were re-evaluated and in three cases diagnosis was revised. RESULTS: In the period 1989 through 2000, 15 patients with BAC and 260 patients with other tumour types underwent surgery in our hospital. Five-year survival rates were 24 and 53%, respectively, (p = 0.01). CONCLUSIONS: Given the poor results after standard surgery, parenchyma-sparing operations do not seem justified in patients with invasive BAC.  相似文献   
992.
993.
994.
995.
996.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
997.
A very high ventilatory response to hypoxia is believed necessary to reach extreme altitude without oxygen. Alternatively, the excessive ventilation could be counterproductive by exhausting the ventilatory reserve early on. To test these alternatives, 11 elite climbers (2004 Everest-K2 Italian Expedition) were evaluated as follows: 1) at sea level, and 2) at 5,200 m, after 15 days of acclimatisation at altitude. Resting oxygen saturation, minute ventilation, breathing rate, hypoxic ventilatory response, maximal voluntary ventilation, ventilatory reserve (at oxygen saturation = 70%) and two indices of ventilatory efficiency were measured. Everest and K2 summits were reached 29 and 61 days, respectively, after the last measurement. Five climbers summited without oxygen, the other six did not, or succeeded with oxygen (two climbers). At sea level, all data were similar. At 5,200 m, the five summiters without oxygen showed lower resting minute ventilation, breathing rate and ventilatory response to hypoxia, and higher ventilatory reserve and ventilatory efficiency, compared to the other climbers. Thus, the more successful climbers had smaller responses to hypoxia during acclimatisation to 5,200 m, but, as a result, had greater available reserve for the summit. A less sensitive hypoxic response and a greater ventilatory efficiency might increase ventilatory reserve and allow sustainable ventilation in the extreme hypoxia at the summit.  相似文献   
998.
There are no data available combining transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and positron emission tomography (PET) in the staging of nonsmall cell lung cancer (NSCLC). The aim of the current study was to determine if these two methods can enhance the negative predictive value of the individual modality alone, for a specific lymph node station, and if this integrated approach can reduce the number of mediastinoscopies. A total of 113 patients with enlarged mediastinal lymph nodes (> or = 1 cm), who underwent both TBNA and PET scanning, were included. In 51 patients, histopathology, confirmed by surgical lymph node dissection, was compared with PET results and TBNA. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy to detect malignant lymphadenopathy was 68 (13/19), 89 (119/134), 46 (13/28), 95 (119/125) and 86% (132/152) for PET, respectively; 54% (6/11), 100 (53/53), 100 (6/6), 91 (53/58) and 92% (59/64), respectively for TBNA; and 100 (11/11), 94 (50/53), 79 (11/14), 100 (50/50) and 95 (61/64) for combined TBNA and PET, respectively. Combination of transbronchial needle aspiration and positron emission tomography has the potential to allow adequate mediastinal staging of nonsmall cell lung cancer with enlarged lymph nodes in most patients without the need for mediastinoscopy.  相似文献   
999.
1000.
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