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   3332篇
  免费   263篇
  国内免费   14篇
耳鼻咽喉   50篇
儿科学   92篇
妇产科学   93篇
基础医学   469篇
口腔科学   44篇
临床医学   312篇
内科学   777篇
皮肤病学   81篇
神经病学   386篇
特种医学   92篇
外科学   317篇
综合类   20篇
一般理论   1篇
预防医学   286篇
眼科学   92篇
药学   177篇
中国医学   5篇
肿瘤学   315篇
  2024年   6篇
  2023年   55篇
  2022年   109篇
  2021年   227篇
  2020年   95篇
  2019年   134篇
  2018年   150篇
  2017年   107篇
  2016年   104篇
  2015年   115篇
  2014年   169篇
  2013年   182篇
  2012年   272篇
  2011年   301篇
  2010年   143篇
  2009年   133篇
  2008年   210篇
  2007年   227篇
  2006年   201篇
  2005年   167篇
  2004年   146篇
  2003年   113篇
  2002年   110篇
  2001年   9篇
  2000年   6篇
  1999年   16篇
  1998年   14篇
  1997年   10篇
  1996年   12篇
  1995年   9篇
  1994年   8篇
  1993年   5篇
  1992年   2篇
  1991年   2篇
  1990年   3篇
  1989年   5篇
  1988年   4篇
  1986年   6篇
  1985年   3篇
  1984年   2篇
  1981年   3篇
  1980年   2篇
  1963年   1篇
  1946年   1篇
  1940年   1篇
  1938年   1篇
  1923年   1篇
  1911年   1篇
  1907年   1篇
  1905年   1篇
排序方式: 共有3609条查询结果,搜索用时 15 毫秒
51.
The question of how far pollen can move between plants has implications for topics as diverse as habitat fragmentation, conservation management, and the containment of genetically modified crops. The monoecious African fig tree Ficus sycomorus L. relies on the small, short-lived, night-flying, host-specific fig wasp Ceratosolen arabicus Mayr for pollination. We used microsatellite markers to characterize a geographically isolated riparian population of F. sycomorus growing along the Ugab River in the Namib Desert, Namibia, together with paternity analysis of seedlings from known mothers, to map pollen movement within this population. In this way we tracked insect movements between individually recognizable trees by means of their pollen cargo and documented the movement of C. arabicus between known trees separated by more than 160 km, with a mean distance for confirmed successful pollination events of 88.6 km. The predominant observed movement of pollinators was in a westerly direction, toward the sea, reflecting seasonal nighttime wind direction and the wind-borne dispersal of fig wasps. Our results suggest the existence of an extensive panmictic population of trees that are well suited to overcome the effects of geographical isolation.  相似文献   
52.
Bilateral dissection of 15 formalin embalmed cadaver legs was performed in order to study the anatomic pattern of the peroneal artery (PA) and its cutaneous perforating vessels (CB). The total number of CB from the PA was 125 or an average of 4.17 branches per leg. CB were distributed in the superoinferior axis between 18.25 and 84.25% of the length of the fibula and their average length was 5 ± 1.8 cm. 86/125 (68.8%) of the CB were classified as myocutaneous branches (MC) that penetrated muscle before reaching the skin, whereas 39/125 (31.2%) were septocutaneous branches (SC) that passed through the intermuscular septum. The mean distance between the posterior border of the fibula and the site where the perforators emerged was 1.88 ± 0.79 cm for the SC and 1.21 ± 0.87 cm for the MC. These anatomic findings should encourage the surgeon to design the skin paddle in the boundary between the middle and the distal third of the fibular length about 2 cm behind the posterior fibular border on the posterolateral leg, where the number of CB is maximal. Clin. Anat. 22:826–833, 2009. © 2009 Wiley‐Liss, Inc.  相似文献   
53.
54.
Objectives. Numeracy, the ability to process basic mathematical concepts, may affect responses to graphical displays of health risk information. Displays of probabilistic risk information using grouped dots are easier to understand than displays using dispersed dots. However, dispersed dots may better convey the randomness with which health threats occur, so increasing perceived susceptibility. We hypothesized that low numeracy participants would better understand risks presented using grouped dot displays, while high numeracy participants would have good understanding, regardless of display type. Moreover, we predicted that dispersed dot displays, in contrast to grouped dot displays, would increase risk perceptions and worry only for highly numerate individuals. Design and method. One hundred and forty smokers read vignettes asking them to imagine being at risk of Crohn's disease, in a 2(display type: dispersed/grouped dots)×3(risk magnitude: 3%/6%/50%)×2(numeracy: high/low) design. They completed measures of risk comprehension, perceived susceptibility and worry. Results. More numerate participants had better objective risk comprehension, but this effect was not moderated by display type. There was marginally significant support for the predicted numeracy × display type interaction for worry about Crohn's disease, but not for perceived susceptibility to the condition. Conclusions. Dispersed dot displays somewhat increase worry in highly numerate individuals, but only numeracy influenced objective risk comprehension. The most effective display type for communicating risk information will depend on the numeracy of the population and the goal(s) of the communication.  相似文献   
55.
56.
57.
58.
BackgroundConventional catheter ablation involves prolonged exposure to ionizing radiation, potentially leading to detrimental health effects. Minimal fluoroscopy (MF) represents a safer alternative, which should be explored. Data on the safety and efficacy of this technique are limited.HypothesisOur hypothesis is that MF is of equal efficacy and safety to conventional catheter ablation with the use of fluoroscopy by performing a meta‐analysis of both randomized controlled trials (RCTs) and real‐world registry studies.MethodsPubmed and Embase were searched from their inception to July 2020 for RCTs, cohort and observational studies that assessed the outcomes of catheter ablation using a MF technique versus the conventional approach.ResultsFifteen studies involving 3795 patients were included in this meta‐analysis. There was a significant reduction in fluoroscopy and procedural time with no difference in acute success (odds ratio [OR]:0.74, 95% CI: 0.50–1.10, p = .14), long‐term success (OR:0.92, 95% CI: 0.65–1.31, p = .38), arrhythmia recurrence (OR:1.24, 95% CI: 0.75–2.06, p = .97) or rate of complications. (OR:0.83, 95% CI: 0.46–1.48, p = .65). Additionally sub‐group analysis for those undergoing catheter ablation for atrial fibrillation (AF) did not demonstrate a difference in success or complication rates (OR:0.86, 95% CI: 0.30–2.42, p = .77). Multivariate meta‐regression did not identify the presence of moderator variables.ConclusionThis updated meta‐analysis demonstrated an overall reduction in procedural and fluoroscopy time for those undergoing a minimal fluoroscopic approach. There was no significant difference in either acute or chronic success rates or complications between a MF approach and conventional approach for the management of all arrhythmias including those undergoing catheter ablation for AF.  相似文献   
59.
60.
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