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   99489篇
  免费   7277篇
  国内免费   513篇
耳鼻咽喉   1238篇
儿科学   2426篇
妇产科学   1435篇
基础医学   12827篇
口腔科学   2438篇
临床医学   9845篇
内科学   21999篇
皮肤病学   1553篇
神经病学   9469篇
特种医学   4032篇
外国民族医学   1篇
外科学   16531篇
综合类   884篇
一般理论   200篇
预防医学   6867篇
眼科学   1870篇
药学   6141篇
中国医学   143篇
肿瘤学   7380篇
  2023年   778篇
  2022年   1217篇
  2021年   3336篇
  2020年   1832篇
  2019年   2854篇
  2018年   3360篇
  2017年   2380篇
  2016年   2565篇
  2015年   2889篇
  2014年   3994篇
  2013年   5122篇
  2012年   7778篇
  2011年   7905篇
  2010年   4337篇
  2009年   3772篇
  2008年   6517篇
  2007年   6321篇
  2006年   6132篇
  2005年   6080篇
  2004年   5496篇
  2003年   5026篇
  2002年   4556篇
  2001年   711篇
  2000年   570篇
  1999年   754篇
  1998年   947篇
  1997年   743篇
  1996年   609篇
  1995年   602篇
  1994年   484篇
  1993年   502篇
  1992年   424篇
  1991年   367篇
  1990年   353篇
  1989年   323篇
  1988年   331篇
  1987年   316篇
  1986年   328篇
  1985年   338篇
  1984年   414篇
  1983年   364篇
  1982年   407篇
  1981年   387篇
  1980年   298篇
  1979年   189篇
  1978年   225篇
  1977年   210篇
  1976年   170篇
  1975年   161篇
  1974年   173篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
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   
3.
4.
5.
6.
Among the chief limitations in achieving early detection and control of animal‐origin influenza of pandemic potential in high‐risk livestock populations is the existing lag time between sample collection and diagnostic result. Advances in molecular diagnostics are permitting deployment of affordable, rapid, highly sensitive, and specific point‐of‐capture assays, providing opportunities for targeted surveillance driving containment strategies with potentially compelling returns on investment. Interrupting disease transmission at source holds promise of disrupting cycles of animal‐origin influenza incursion to endemicity and limiting impact on animal production, food security, and public health. Adoption of new point‐of‐capture diagnostics should be undertaken in the context of promoting robust veterinary services systems and parallel support for operationalizing pre‐authorized plans and communication strategies that will ensure that the full potential of these new platforms is realized.  相似文献   
7.
8.
This article describes a case of anaphylaxis secondary to chlorhexidine during urethral catheterisation. Despite little evidence for the use of antiseptic lubricants in preventing catheter-associated urinary tract infections, the distribution and use of such products continues to be widespread. Chlorhexidine-free lubricating gel is widely available and should be used for urological procedures wherever possible.  相似文献   
9.
(+/?)3,4‐methylenedioxymethamphetamine (MDMA, “ecstasy”) is an abused psychostimulant that produces strong monoaminergic stimulation and whole‐body hyperthermia. MDMA‐induced thermogenesis involves activation of uncoupling proteins (UCPs), primarily a type specific to skeletal muscle (UCP‐3) and absent from the brain, although other UCP types are expressed in the brain (e.g. thalamus) and might contribute to thermogenesis. Since neuroimaging of brain temperature could provide insights into MDMA action, we measured spatial distributions of systemically administered MDMA‐induced temperature changes and dynamics in rat cortex and subcortex using a novel magnetic resonance method, Biosensor Imaging of Redundant Deviation in Shifts (BIRDS), with an exogenous temperature‐sensitive probe (thulium ion and macrocyclic chelate 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetramethyl‐1,4,7,10‐tetraacetate (DOTMA4?)). The MDMA‐induced temperature rise was greater in the cortex than in the subcortex (1.6 ± 0.4 °C versus 1.3 ± 0.4 °C) and occurred more rapidly (2.0 ± 0.2 °C/h versus 1.5 ± 0.2 °C/h). MDMA‐induced temperature changes and dynamics in the cortex and body were correlated, although the body temperature exceeded the cortex temperature before and after MDMA. Temperature, neuronal activity, and blood flow (CBF) were measured simultaneously in the cortex and subcortex (i.e. thalamus) to investigate possible differences of MDMA‐induced warming across brain regions. MDMA‐induced warming correlated with increases in neuronal activity and blood flow in the cortex, suggesting that the normal neurovascular response to increased neural activity was maintained. In contrast to the cortex, a biphasic relationship was seen in the subcortex (i.e. thalamus), with a decline in CBF as temperature and neural activity rose, transitioning to a rise in CBF for temperature above 37 °C, suggesting that MDMA affected CBF and neurovascular coupling differently in subcortical regions. Considering that MDMA effects on CBF and heat dissipation (as well as potential heat generation) may vary regionally, neuroprotection may require different cooling strategies. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
10.
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