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   1367282篇
  免费   93151篇
  国内免费   4305篇
耳鼻咽喉   17121篇
儿科学   44068篇
妇产科学   36778篇
基础医学   200999篇
口腔科学   36676篇
临床医学   132177篇
内科学   262815篇
皮肤病学   26563篇
神经病学   114430篇
特种医学   49032篇
外国民族医学   368篇
外科学   186764篇
综合类   29172篇
现状与发展   1篇
一般理论   482篇
预防医学   116176篇
眼科学   29503篇
药学   100729篇
  36篇
中国医学   3221篇
肿瘤学   77627篇
  2021年   11483篇
  2019年   12445篇
  2018年   16686篇
  2017年   12676篇
  2016年   13712篇
  2015年   15621篇
  2014年   21420篇
  2013年   32897篇
  2012年   45532篇
  2011年   48261篇
  2010年   27935篇
  2009年   25645篇
  2008年   44092篇
  2007年   46389篇
  2006年   46505篇
  2005年   45002篇
  2004年   42884篇
  2003年   40782篇
  2002年   39523篇
  2001年   61096篇
  2000年   62695篇
  1999年   52551篇
  1998年   14898篇
  1997年   13501篇
  1996年   13336篇
  1995年   12668篇
  1994年   11804篇
  1993年   11066篇
  1992年   41707篇
  1991年   40880篇
  1990年   39557篇
  1989年   37458篇
  1988年   34709篇
  1987年   33801篇
  1986年   32269篇
  1985年   30758篇
  1984年   23163篇
  1983年   19718篇
  1982年   11916篇
  1979年   20885篇
  1978年   14914篇
  1977年   12158篇
  1976年   11949篇
  1975年   12187篇
  1974年   14859篇
  1973年   14525篇
  1972年   13402篇
  1971年   12458篇
  1970年   11511篇
  1969年   10436篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
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   
52.
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   
53.
54.
55.
56.
57.
French asthma patients may be supervised by general practitioners (GPs) and/or specialists. Therefore, this study examined asthma management in patients exclusively supervised by specialists (SPE), GPs, (GP) and both (GP+SPE group), and compared the findings. Asthma patients were consecutively recruited in 348 pharmacies. Each patient completed a questionnaire providing data on personal characteristics, asthma management, perception of disease and asthma supervision. Asthma control was measured using the Asthma Control Test. Questionnaires were linked to computerised records of medications which had been dispensed before inclusion in the study. From the 1,256 patients (mean age = 36.1 yrs, 54.3% females), 11.4, 36.6, and 52.0% were placed in the SPE, GP, and GP+SPE groups, respectively. During the previous 4 weeks, most patients in the SPE group were properly controlled (52.2 versus 26.4 and 21.5% in GP and GP+SPE groups, respectively). The SPE group made more use of fixed combinations of long-acting beta agonist and inhaled corticosteroid, while receiving less short-acting beta agonists, antitussives and antibiotics. Striking differences in symptoms and asthma management were observed according to the type of asthma supervision. The current results strongly support the need to improve the management of asthma in primary care, and the coordination of care between general practitioners and specialists.  相似文献   
58.
59.
Research coordinators in intensive care are a growing specialty about which little is known. This cross-sectional study surveyed the Australia and New Zealand Intensive Care Research Coordinators' Group (n = 49) regarding demographics, education, employment history, job structure, and role content. Most research coordinators were highly qualified and experienced nurses who undertake pharmaceutical trials, multicenter projects, departmental medical and nursing research, audits and data registries, and their own projects.  相似文献   
60.
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