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   4932315篇
  免费   388041篇
  国内免费   15415篇
耳鼻咽喉   69814篇
儿科学   160198篇
妇产科学   131550篇
基础医学   739623篇
口腔科学   135664篇
临床医学   451390篇
内科学   904444篇
皮肤病学   118535篇
神经病学   411046篇
特种医学   192852篇
外国民族医学   1299篇
外科学   743470篇
综合类   136431篇
现状与发展   24篇
一般理论   2794篇
预防医学   407449篇
眼科学   116782篇
药学   352636篇
  25篇
中国医学   13107篇
肿瘤学   246638篇
  2021年   57053篇
  2019年   59616篇
  2018年   76524篇
  2017年   58232篇
  2016年   64501篇
  2015年   76972篇
  2014年   111349篇
  2013年   177260篇
  2012年   140361篇
  2011年   148315篇
  2010年   131246篇
  2009年   131188篇
  2008年   134084篇
  2007年   144063篇
  2006年   151383篇
  2005年   145530篇
  2004年   146403篇
  2003年   136374篇
  2002年   125557篇
  2001年   196580篇
  2000年   193517篇
  1999年   174559篇
  1998年   75687篇
  1997年   70257篇
  1996年   68288篇
  1995年   63662篇
  1994年   57711篇
  1993年   53502篇
  1992年   128251篇
  1991年   123142篇
  1990年   118860篇
  1989年   115458篇
  1988年   106440篇
  1987年   104346篇
  1986年   98096篇
  1985年   95450篇
  1984年   77441篇
  1983年   68266篇
  1982年   51226篇
  1981年   47517篇
  1980年   44394篇
  1979年   67222篇
  1978年   52467篇
  1977年   46434篇
  1976年   43040篇
  1975年   43944篇
  1974年   48472篇
  1973年   46456篇
  1972年   43486篇
  1971年   40124篇
排序方式: 共有10000条查询结果,搜索用时 31 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