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   4365847篇
  免费   350860篇
  国内免费   14688篇
耳鼻咽喉   60534篇
儿科学   140299篇
妇产科学   114881篇
基础医学   669475篇
口腔科学   118528篇
临床医学   400073篇
内科学   792176篇
皮肤病学   108025篇
神经病学   370486篇
特种医学   169984篇
外国民族医学   758篇
外科学   658676篇
综合类   121604篇
现状与发展   24篇
一般理论   2659篇
预防医学   361184篇
眼科学   101381篇
药学   308953篇
  23篇
中国医学   11944篇
肿瘤学   219728篇
  2021年   56491篇
  2020年   36049篇
  2019年   59106篇
  2018年   74811篇
  2017年   56998篇
  2016年   63161篇
  2015年   75994篇
  2014年   110322篇
  2013年   176120篇
  2012年   126422篇
  2011年   131476篇
  2010年   126699篇
  2009年   128124篇
  2008年   117255篇
  2007年   124658篇
  2006年   133270篇
  2005年   127364篇
  2004年   128483篇
  2003年   118556篇
  2002年   107775篇
  2001年   167194篇
  2000年   162300篇
  1999年   148895篇
  1998年   71789篇
  1997年   67693篇
  1996年   65705篇
  1995年   61111篇
  1994年   55036篇
  1993年   51068篇
  1992年   106809篇
  1991年   101542篇
  1990年   97424篇
  1989年   94969篇
  1988年   87302篇
  1987年   85444篇
  1986年   80332篇
  1985年   78490篇
  1984年   65487篇
  1983年   58290篇
  1982年   47234篇
  1981年   43905篇
  1980年   41123篇
  1979年   55241篇
  1978年   44827篇
  1977年   40037篇
  1976年   36894篇
  1975年   36864篇
  1974年   39704篇
  1973年   37834篇
  1972年   35443篇
排序方式: 共有10000条查询结果,搜索用时 375 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