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   4624137篇
  免费   384026篇
  国内免费   16041篇
耳鼻咽喉   66748篇
儿科学   143833篇
妇产科学   122751篇
基础医学   699026篇
口腔科学   131581篇
临床医学   420426篇
内科学   839655篇
皮肤病学   109659篇
神经病学   394102篇
特种医学   185076篇
外国民族医学   1067篇
外科学   704958篇
综合类   138880篇
现状与发展   24篇
一般理论   2704篇
预防医学   389903篇
眼科学   110253篇
药学   330026篇
  21篇
中国医学   12186篇
肿瘤学   221325篇
  2021年   55885篇
  2019年   58751篇
  2018年   73989篇
  2017年   56255篇
  2016年   62770篇
  2015年   75686篇
  2014年   110505篇
  2013年   175941篇
  2012年   127729篇
  2011年   132439篇
  2010年   125689篇
  2009年   127914篇
  2008年   119156篇
  2007年   127703篇
  2006年   136296篇
  2005年   131344篇
  2004年   132474篇
  2003年   122898篇
  2002年   113294篇
  2001年   169265篇
  2000年   166209篇
  1999年   152151篇
  1998年   73273篇
  1997年   69149篇
  1996年   66947篇
  1995年   62848篇
  1994年   56978篇
  1993年   52857篇
  1992年   114947篇
  1991年   110165篇
  1990年   105452篇
  1989年   102518篇
  1988年   95584篇
  1987年   94049篇
  1986年   89158篇
  1985年   87363篇
  1984年   72859篇
  1983年   64641篇
  1982年   50761篇
  1981年   47021篇
  1980年   44233篇
  1979年   65896篇
  1978年   52240篇
  1977年   45858篇
  1976年   42600篇
  1975年   42526篇
  1974年   48733篇
  1973年   46847篇
  1972年   44000篇
  1971年   40382篇
排序方式: 共有10000条查询结果,搜索用时 281 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