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   2414篇
  免费   143篇
  国内免费   28篇
耳鼻咽喉   3篇
儿科学   205篇
妇产科学   37篇
基础医学   215篇
口腔科学   71篇
临床医学   262篇
内科学   569篇
皮肤病学   40篇
神经病学   87篇
特种医学   379篇
外科学   147篇
综合类   43篇
预防医学   190篇
眼科学   31篇
药学   138篇
  1篇
中国医学   1篇
肿瘤学   166篇
  2021年   19篇
  2020年   17篇
  2019年   19篇
  2018年   35篇
  2017年   26篇
  2016年   35篇
  2015年   41篇
  2014年   51篇
  2013年   74篇
  2012年   51篇
  2011年   53篇
  2010年   53篇
  2009年   87篇
  2008年   48篇
  2007年   57篇
  2006年   64篇
  2005年   59篇
  2004年   51篇
  2003年   58篇
  2002年   51篇
  2001年   44篇
  2000年   46篇
  1999年   57篇
  1998年   115篇
  1997年   125篇
  1996年   117篇
  1995年   86篇
  1994年   94篇
  1993年   110篇
  1992年   42篇
  1991年   40篇
  1990年   47篇
  1989年   84篇
  1988年   75篇
  1987年   53篇
  1986年   60篇
  1985年   71篇
  1984年   38篇
  1983年   30篇
  1982年   29篇
  1981年   47篇
  1980年   30篇
  1979年   37篇
  1978年   18篇
  1977年   26篇
  1976年   27篇
  1975年   15篇
  1974年   9篇
  1973年   11篇
  1970年   10篇
排序方式: 共有2585条查询结果,搜索用时 406 毫秒
41.
42.
Rigor and resistance to stretch in vertebrate smooth muscle   总被引:2,自引:0,他引:2  
  相似文献   
43.
44.
45.
46.
Surfactant protein A (SP-A), a member of the collectin family, selectively binds to Pneumocystis carinii and mediates interactions between pathogen and host alveolar macrophages in vitro. To test the hypothesis that mice lacking SP-A have delayed clearance of Pneumocystis organisms and enhanced lung injury, wild-type C57BL/6 (WT) and SP-A-deficient mice (SP-A(-/-)) with or without selective CD4(+)-T-cell depletion were intratracheally inoculated with Pneumocystis organisms. Four weeks later, CD4-depleted SP-A-deficient mice had developed a more severe Pneumocystis infection than CD4-depleted WT (P. carinii pneumonia [PCP] scores of 3 versus 2, respectively). Whereas all non-CD4-depleted WT mice were free of PCP, intact SP-A(-/-) mice also had evidence of increased organism burden. Pneumocystis infection in SP-A-deficient mice was associated histologically with enhanced peribronchial and/or perivascular cellularity (score of 4 versus 2, SP-A(-/-) versus C57BL/6 mice, respectively) and a corresponding increase in bronchoalveolar lavage (BAL) cell counts. Increases in SP-D content, gamma interferon, interleukin-4, interleukin-5, and tumor necrosis factor alpha in BAL fluid occurred but were attenuated in PCP-infected SP-A(-/-) mice compared to WT mice. There were increases in total BAL NO levels in both infected groups, but nitrite levels were higher in SP-A(-/-) mice, indicating a reduction in production of higher oxides of nitrogen that was also reflected in lower levels of 3-nitrotyrosine staining in the SP-A(-/-) group. We conclude that despite increases in inflammatory cells, SP-A-deficient mice infected with P. carinii exhibit an enhanced susceptibility to the organism and attenuated production of proinflammatory cytokines and reactive oxygen-nitrogen species. These data support the concept that SP-A is a local effector molecule in the lung host defense against P. carinii in vivo.  相似文献   
47.
BackgroundMinimal invasive surgery (MIS) is increasingly used for the correction of congenital diaphragmatic hernia (CDH) and esophageal atresia (EA). It is important to master these complex procedures, preferably preclinically, to avoid complications. The aim of this study was to validate recently developed models to train these MIS procedures preclinically.MethodsTwo low cost, reproducible models (one for CDH and one for EA) were validated during several pediatric surgical conferences and training sessions (January 2017–December 2018), used in either the LaparoscopyBoxx or EoSim simulator. Participants used one or both models and completed a questionnaire regarding their opinion on realism (face validity) and didactic value (content validity), rated on a five-point-Likert scale.ResultsOf all 60 participants enrolled, 44 evaluated the EA model. All items were evaluated as significantly better than neutral, with means ranging from 3.7 to 4.1 (p < 0.001). The CDH model was evaluated by 48 participants. All items scored significantly better than neutral (means 3.5–3.9, p < 0.001), with exception of the haptics of the simulated diaphragm (mean 3.3, p = 0.054). Both models were considered a potent training tool (means 3.9).ConclusionThese readily available and low budget models are considered a valid and potent training tool by both experts and target group participants.Type of studyProspective study.Level of evidenceLevel II.  相似文献   
48.
Lung carcinoma remains one of the most frequent and aggressive human neoplasms. Fortunately, in the last decades, the increasing knowledge of the molecular mechanisms leading to cancer development has allowed the use of targeted therapies with improvement of prognosis in many patients. Clinical management has also changed after the introduction of endobronchialultrasonographic bronchoscopy that allows a conservative staging of lung tumors, avoiding the need of mediastinoscopy for lymph node staging. Lung pathologists and cytopathologists are facing the challenge of giving the more comprehensive prognostic and predictive information with ever smaller tissue or cytological samples. The aim of this review is to summarize the molecular testing for non-small cell lung carcinoma and how pathologists can contribute to the patient's outcome with a conscious management of biological samples.  相似文献   
49.
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