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   59400篇
  免费   6367篇
  国内免费   220篇
耳鼻咽喉   701篇
儿科学   1973篇
妇产科学   1594篇
基础医学   6515篇
口腔科学   996篇
临床医学   12047篇
内科学   10251篇
皮肤病学   812篇
神经病学   5334篇
特种医学   1387篇
外国民族医学   1篇
外科学   6457篇
综合类   681篇
一般理论   54篇
预防医学   7798篇
眼科学   968篇
药学   3293篇
中国医学   67篇
肿瘤学   5058篇
  2024年   114篇
  2023年   844篇
  2022年   602篇
  2021年   1202篇
  2020年   1080篇
  2019年   1206篇
  2018年   1925篇
  2017年   1683篇
  2016年   1690篇
  2015年   1791篇
  2014年   2365篇
  2013年   3245篇
  2012年   3796篇
  2011年   4026篇
  2010年   2552篇
  2009年   2502篇
  2008年   3526篇
  2007年   3479篇
  2006年   3495篇
  2005年   3354篇
  2004年   3148篇
  2003年   2807篇
  2002年   2698篇
  2001年   910篇
  2000年   758篇
  1999年   870篇
  1998年   913篇
  1997年   821篇
  1996年   825篇
  1995年   645篇
  1994年   604篇
  1993年   527篇
  1992年   590篇
  1991年   546篇
  1990年   417篇
  1989年   424篇
  1988年   397篇
  1987年   361篇
  1986年   329篇
  1985年   296篇
  1984年   271篇
  1983年   236篇
  1982年   220篇
  1981年   213篇
  1980年   166篇
  1979年   198篇
  1978年   133篇
  1977年   143篇
  1976年   117篇
  1974年   122篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This study analyzed midwife and doula information on pregnancy and childbirth websites originating in the U.S. A two-fold sampling process of top Google search results and purposive sampling of pregnancy and childbirth websites was used. Most websites published articles about midwives and doulas making it relatively easy to find information if one were to search, but not necessarily if browsing commonly used websites. Themes on the websites’ scant discussion forums evidenced readers’ interest in midwife and doula services. Findings reveal a need to make discussion forums and midwife and doula services more accessible on pregnancy and childbirth websites.  相似文献   
992.
993.
994.
This multicenter study analyzed Nocardia spp., including extraction, spectral acquisition, Bruker matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identification, and score interpretation, using three Nocardia libraries, the Bruker, National Institutes of Health (NIH), and The Ohio State University (OSU) libraries, and compared the results obtained by each center. A standardized study protocol, 150 Nocardia isolates, and NIH and OSU Nocardia MALDI-TOF MS libraries were distributed to three centers. Following standardized culture, extraction, and MALDI-TOF MS analysis, isolates were identified using score cutoffs of ≥2.0 for species/species complex-level identification and ≥1.8 for genus-level identification. Isolates yielding a score of <2.0 underwent a single repeat extraction and analysis. The overall score range for all centers was 1.3 to 2.7 (average, 2.2 ± 0.3), with common species generally producing higher average scores than less common ones. Score categorization and isolate identification demonstrated 86% agreement between centers; 118 of 150 isolates were correctly identified to the species/species complex level by all centers. Nine strains (6.0%) were not identified by any center, and six (4.0%) of these were uncommon species with limited library representation. A categorical score discrepancy among centers occurred for 21 isolates (14.0%). There was an overall benefit of 21.2% from repeat extraction of low-scoring isolates and a center-dependent benefit for duplicate spotting (range, 2 to 8.7%). Finally, supplementation of the Bruker Nocardia MALDI-TOF MS library with both the OSU and NIH libraries increased the genus-level and species-level identification by 18.2% and 36.9%, respectively. Overall, this study demonstrates the ability of diverse clinical microbiology laboratories to utilize MALDI-TOF MS for the rapid identification of clinically relevant Nocardia spp. and to implement MALDI-TOF MS libraries developed by single laboratories across institutions.  相似文献   
995.
996.
997.
998.
BackgroundThe prevalence of fungal disease in cystic fibrosis (CF) and non-CF bronchiectasis is increasing and the clinical spectrum is widening. Poor sensitivity and a lack of standard diagnostic criteria renders interpretation of culture results challenging. In order to develop effective management strategies, a more accurate and comprehensive understanding of the airways fungal microbiome is required. The study aimed to use DNA sequences from sputum to assess the load and diversity of fungi in adults with CF and non-CF bronchiectasis.MethodsNext generation sequencing of the ITS2 region was used to examine fungal community composition (n = 176) by disease and underlying clinical subgroups including allergic bronchopulmonary aspergillosis, chronic necrotizing pulmonary aspergillosis, non-tuberculous mycobacteria, and fungal bronchitis. Patients with no known active fungal disease were included as disease controls.ResultsITS2 sequencing greatly increased the detection of fungi from sputum. In patients with CF fungal diversity was lower, while burden was higher than those with non-CF bronchiectasis. The most common operational taxonomic unit (OTU) in patients with CF was Candida parapsilosis (20.4%), whereas in non-CF bronchiectasis sputum Candida albicans (21.8%) was most common. CF patients with overt fungal bronchitis were dominated by Aspergillus spp., Exophiala spp., Candida parapsilosis or Scedosporium spp.ConclusionThis study provides a framework to more accurately characterize the extended spectrum of fungal airways diseases in adult suppurative lung diseases.  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