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   4400999篇
  免费   364066篇
  国内免费   15737篇
耳鼻咽喉   62827篇
儿科学   137605篇
妇产科学   115394篇
基础医学   671602篇
口腔科学   123702篇
临床医学   400018篇
内科学   799160篇
皮肤病学   106879篇
神经病学   374959篇
特种医学   176683篇
外国民族医学   987篇
外科学   671804篇
综合类   126912篇
现状与发展   23篇
一般理论   2592篇
预防医学   372595篇
眼科学   103217篇
药学   311282篇
  26篇
中国医学   11501篇
肿瘤学   211034篇
  2021年   56366篇
  2019年   59133篇
  2018年   74088篇
  2017年   56600篇
  2016年   63466篇
  2015年   78381篇
  2014年   113057篇
  2013年   178405篇
  2012年   123248篇
  2011年   124818篇
  2010年   125146篇
  2009年   129243篇
  2008年   111296篇
  2007年   118572篇
  2006年   127973篇
  2005年   122915篇
  2004年   123282篇
  2003年   113735篇
  2002年   104651篇
  2001年   156764篇
  2000年   151480篇
  1999年   142939篇
  1998年   71840篇
  1997年   68078篇
  1996年   65948篇
  1995年   61790篇
  1994年   55877篇
  1993年   51827篇
  1992年   107910篇
  1991年   103685篇
  1990年   99055篇
  1989年   96455篇
  1988年   89760篇
  1987年   87993篇
  1986年   83696篇
  1985年   81637篇
  1984年   68570篇
  1983年   60931篇
  1982年   48848篇
  1981年   45421篇
  1980年   42774篇
  1979年   60661篇
  1978年   48798篇
  1977年   42986篇
  1976年   39883篇
  1975年   39841篇
  1974年   44881篇
  1973年   42706篇
  1972年   40242篇
  1971年   37033篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Intratumor heterogeneity is a main cause of the dismal prognosis of glioblastoma (GBM). Yet, there remains a lack of a uniform assessment of the degree of heterogeneity. With a multiscale approach, we addressed the hypothesis that intratumor heterogeneity exists on different levels comprising traditional regional analyses, but also innovative methods including computer-assisted analysis of tumor morphology combined with epigenomic data. With this aim, 157 biopsies of 37 patients with therapy-naive IDH-wildtype GBM were analyzed regarding the intratumor variance of protein expression of glial marker GFAP, microglia marker Iba1 and proliferation marker Mib1. Hematoxylin and eosin stained slides were evaluated for tumor vascularization. For the estimation of pixel intensity and nuclear profiling, automated analysis was used. Additionally, DNA methylation profiling was conducted separately for the single biopsies. Scoring systems were established to integrate several parameters into one score for the four examined modalities of heterogeneity (regional, cellular, pixel-level and epigenomic). As a result, we could show that heterogeneity was detected in all four modalities. Furthermore, for the regional, cellular and epigenomic level, we confirmed the results of earlier studies stating that a higher degree of heterogeneity is associated with poorer overall survival. To integrate all modalities into one score, we designed a predictor of longer survival, which showed a highly significant separation regarding the OS. In conclusion, multiscale intratumor heterogeneity exists in glioblastoma and its degree has an impact on overall survival. In future studies, the implementation of a broadly feasible heterogeneity index should be considered.  相似文献   
12.
Journal of Medical Ultrasonics - Chronic liver disease is still a major problem because disease progression will ultimately lead to liver cirrhosis. Portal hypertension is the hallmark in advanced...  相似文献   
13.
14.
15.
16.
17.
18.
19.
PurposeUnderstanding the value of genetic screening and testing for monogenic disorders requires high-quality, methodologically robust economic evaluations. This systematic review sought to assess the methodological quality among such studies and examined opportunities for improvement.MethodsWe searched PubMed, Cochrane, Embase, and Web of Science for economic evaluations of genetic screening/testing (2013-2019). Methodological rigor and adherence to best practices were systematically assessed using the British Medical Journal checklist.ResultsAcross the 47 identified studies, there were substantial variations in modeling approaches, reporting detail, and sophistication. Models ranged from simple decision trees to individual-level microsimulations that compared between 2 and >20 alternative interventions. Many studies failed to report sufficient detail to enable replication or did not justify modeling assumptions, especially for costing methods and utility values. Meta-analyses, systematic reviews, or calibration were rarely used to derive parameter estimates. Nearly all studies conducted some sensitivity analysis, and more sophisticated studies implemented probabilistic sensitivity/uncertainty analysis, threshold analysis, and value of information analysis.ConclusionWe describe a heterogeneous body of work and present recommendations and exemplar studies across the methodological domains of (1) perspective, scope, and parameter selection; (2) use of uncertainty/sensitivity analyses; and (3) reporting transparency for improvement in the economic evaluation of genetic screening/testing.  相似文献   
20.

The exercise pressor reflex is a feedback mechanism engaged upon stimulation of mechano- and metabosensitive skeletal muscle afferents. Activation of these afferents elicits a reflex increase in heart rate, blood pressure, and ventilation in an intensity-dependent manner. Consequently, the exercise pressor reflex has been postulated to be one of the principal mediators of the cardiorespiratory responses to exercise. In this updated review, we will discuss classical and recent advancements in our understating of the exercise pressor reflex function in both human and animal models. Particular attention will be paid to the afferent mechanisms and pathways involved during its activation, its effects on different target organs, its potential role in the abnormal cardiovascular response to exercise in diseased states, and the impact of age and biological sex on these responses. Finally, we will highlight some unanswered questions in the literature that may inspire future investigations in the field.

  相似文献   
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