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   4340512篇
  免费   349504篇
  国内免费   14661篇
耳鼻咽喉   60267篇
儿科学   139384篇
妇产科学   114188篇
基础医学   666341篇
口腔科学   117936篇
临床医学   396345篇
内科学   788230篇
皮肤病学   107705篇
神经病学   368049篇
特种医学   169399篇
外国民族医学   753篇
外科学   655891篇
综合类   121221篇
现状与发展   24篇
一般理论   2614篇
预防医学   357945篇
眼科学   100933篇
药学   307428篇
  23篇
中国医学   11934篇
肿瘤学   218067篇
  2021年   56137篇
  2020年   35825篇
  2019年   58814篇
  2018年   74354篇
  2017年   56643篇
  2016年   62785篇
  2015年   75699篇
  2014年   109956篇
  2013年   175510篇
  2012年   124263篇
  2011年   129021篇
  2010年   125886篇
  2009年   127599篇
  2008年   115206篇
  2007年   122447篇
  2006年   131272篇
  2005年   125347篇
  2004年   126659篇
  2003年   116860篇
  2002年   106130篇
  2001年   166960篇
  2000年   162031篇
  1999年   148693篇
  1998年   71663篇
  1997年   67613篇
  1996年   65630篇
  1995年   61044篇
  1994年   54973篇
  1993年   51015篇
  1992年   106626篇
  1991年   101398篇
  1990年   97253篇
  1989年   94829篇
  1988年   87148篇
  1987年   85312篇
  1986年   80207篇
  1985年   78358篇
  1984年   65398篇
  1983年   58198篇
  1982年   47187篇
  1981年   43858篇
  1980年   41074篇
  1979年   55109篇
  1978年   44755篇
  1977年   39981篇
  1976年   36839篇
  1975年   36808篇
  1974年   39612篇
  1973年   37756篇
  1972年   35369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