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   3425595篇
  免费   246670篇
  国内免费   9361篇
耳鼻咽喉   48382篇
儿科学   111476篇
妇产科学   97315篇
基础医学   482011篇
口腔科学   97260篇
临床医学   308519篇
内科学   669378篇
皮肤病学   81699篇
神经病学   279970篇
特种医学   132724篇
外国民族医学   1122篇
外科学   516660篇
综合类   72841篇
现状与发展   11篇
一般理论   1305篇
预防医学   256833篇
眼科学   79077篇
药学   252568篇
  11篇
中国医学   7130篇
肿瘤学   185334篇
  2018年   36018篇
  2017年   27981篇
  2016年   32183篇
  2015年   36247篇
  2014年   50130篇
  2013年   75662篇
  2012年   99872篇
  2011年   105777篇
  2010年   63811篇
  2009年   61185篇
  2008年   99445篇
  2007年   106415篇
  2006年   107956篇
  2005年   103858篇
  2004年   100317篇
  2003年   97179篇
  2002年   94073篇
  2001年   160926篇
  2000年   165001篇
  1999年   139573篇
  1998年   40175篇
  1997年   35834篇
  1996年   35494篇
  1995年   34238篇
  1994年   31581篇
  1993年   29611篇
  1992年   109129篇
  1991年   105356篇
  1990年   102383篇
  1989年   99316篇
  1988年   91599篇
  1987年   89845篇
  1986年   84877篇
  1985年   81129篇
  1984年   60799篇
  1983年   51652篇
  1982年   30954篇
  1981年   27740篇
  1979年   55280篇
  1978年   39284篇
  1977年   33853篇
  1976年   31057篇
  1975年   34039篇
  1974年   40128篇
  1973年   38521篇
  1972年   36393篇
  1971年   33960篇
  1970年   31679篇
  1969年   30565篇
  1968年   28358篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
951.
952.
953.
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   
954.
955.
A national conference on organ donation after cardiac death (DCD) was convened to expand the practice of DCD in the continuum of quality end-of-life care. This national conference affirmed the ethical propriety of DCD as not violating the dead donor rule. Further, by new developments not previously reported, the conference resolved controversy regarding the period of circulatory cessation that determines death and allows administration of pre-recovery pharmacologic agents, it established conditions of DCD eligibility, it presented current data regarding the successful transplantation of organs from DCD, it proposed a new framework of data reporting regarding ischemic events, it made specific recommendations to agencies and organizations to remove barriers to DCD, it brought guidance regarding organ allocation and the process of informed consent and it set an action plan to address media issues. When a consensual decision is made to withdraw life support by the attending physician and patient or by the attending physician and a family member or surrogate (particularly in an intensive care unit), a routine opportunity for DCD should be available to honor the deceased donor's wishes in every donor service area (DSA) of the United States.  相似文献   
956.
目的:在瑞典儿童群体中,研究瑞典语译的出院后行为学问卷调查(PHBQ)的有效性和可行性。方法:利用回译的方法,将PHBQ翻译成瑞典语。340名2~13岁间的小儿被纳入研究对象,均曾有过麻醉下接受选择性外科手术或诊断过程的住院史。利用旋光性甲戊炔醇主成分分析的探测性因素分析法分析结果。选择一匹配于该模型的可靠的适合度测量法,利用证实性的因素分析,检查数据的适合度(所有因素P〉0.09)。  相似文献   
957.
958.
Effect of catalase supplementation in storage media for avulsed teeth   总被引:1,自引:0,他引:1  
Abstract – The type of liquid medium used to store avulsed teeth prior to replantation has been shown to affect the long‐term prognosis. One possibility is that some storage media contain hydrogen peroxide (H2O2) that may be toxic to periodontal ligament cells. Therefore, the aim of this study was to determine if the addition of catalase to storage media improved the prognosis of replanted dog teeth. Forty‐eight mongrel premolar roots were endodontically treated, extracted, randomly divided and placed into one of four storage media: Hank's balanced salt solution (HBSS), containing no antioxidant); Viaspan, containing the antioxidant, glutathione, or the same two media supplemented with catalase(100 U ml?1) for 1, 5, or 26 h prior to replantation. After 2 months, the dogs were euthanized and the roots histologically examined to evaluate the attachment tissues. Regardless of the storage medium used, overall healing was excellent and only 4% of the roots displayed inflammatory or replacement resorption. When roots from the different storage media were compared, those stored in HBSS were found to display the highest incidence of surface resorption (55.7%). Supplementation of HBSS with catalase resulted in a lower level of surface resorption (48.6%) that was statistically significant (P < 0.05). Roots stored in Viaspan – or + catalase displayed even lower levels of surface resorption (41.3 and 38.2%, respectively). The improvement observed with catalase‐supplemented HBSS was confined to the 45‐min incubation period; only Viaspan – or + catalase reduced surface resorption at the 5‐ and 26‐h incubations. Collectively, these data demonstrate that roots stored in media containing antioxidant activity undergo less surface resorption. These results suggest that low levels of H2O2 in storage media for avulsed teeth may adversely affect periodontal ligament cells.  相似文献   
959.
960.
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