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   4858215篇
  免费   377997篇
  国内免费   15340篇
耳鼻咽喉   67841篇
儿科学   155691篇
妇产科学   128714篇
基础医学   732300篇
口腔科学   134357篇
临床医学   447285篇
内科学   881993篇
皮肤病学   118476篇
神经病学   404586篇
特种医学   189718篇
外国民族医学   935篇
外科学   728652篇
综合类   134684篇
现状与发展   24篇
一般理论   2778篇
预防医学   398841篇
眼科学   114935篇
药学   350531篇
  26篇
中国医学   13320篇
肿瘤学   245865篇
  2021年   56982篇
  2019年   59366篇
  2018年   76073篇
  2017年   58124篇
  2016年   64506篇
  2015年   76969篇
  2014年   111394篇
  2013年   177282篇
  2012年   139257篇
  2011年   146572篇
  2010年   130754篇
  2009年   130920篇
  2008年   131912篇
  2007年   141452篇
  2006年   149147篇
  2005年   143035篇
  2004年   143643篇
  2003年   133522篇
  2002年   122444篇
  2001年   195396篇
  2000年   191800篇
  1999年   172770篇
  1998年   75176篇
  1997年   69979篇
  1996年   68038篇
  1995年   63504篇
  1994年   57266篇
  1993年   53099篇
  1992年   125794篇
  1991年   120357篇
  1990年   116157篇
  1989年   113148篇
  1988年   103905篇
  1987年   101548篇
  1986年   96031篇
  1985年   93194篇
  1984年   75788篇
  1983年   66609篇
  1982年   50680篇
  1981年   46743篇
  1980年   43877篇
  1979年   65350篇
  1978年   51049篇
  1977年   45711篇
  1976年   41832篇
  1975年   42831篇
  1974年   47046篇
  1973年   45087篇
  1972年   42413篇
  1971年   39292篇
排序方式: 共有10000条查询结果,搜索用时 625 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