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   5613篇
  免费   245篇
  国内免费   20篇
耳鼻咽喉   34篇
儿科学   230篇
妇产科学   76篇
基础医学   518篇
口腔科学   105篇
临床医学   419篇
内科学   1232篇
皮肤病学   179篇
神经病学   416篇
特种医学   168篇
外科学   969篇
综合类   105篇
预防医学   233篇
眼科学   280篇
药学   498篇
  1篇
中国医学   36篇
肿瘤学   379篇
  2024年   2篇
  2023年   37篇
  2022年   115篇
  2021年   209篇
  2020年   105篇
  2019年   137篇
  2018年   157篇
  2017年   116篇
  2016年   163篇
  2015年   183篇
  2014年   266篇
  2013年   366篇
  2012年   527篇
  2011年   520篇
  2010年   275篇
  2009年   242篇
  2008年   382篇
  2007年   402篇
  2006年   369篇
  2005年   318篇
  2004年   312篇
  2003年   231篇
  2002年   176篇
  2001年   36篇
  2000年   34篇
  1999年   28篇
  1998年   25篇
  1997年   27篇
  1996年   18篇
  1995年   18篇
  1994年   15篇
  1993年   17篇
  1992年   4篇
  1991年   6篇
  1990年   12篇
  1989年   7篇
  1988年   4篇
  1987年   5篇
  1986年   1篇
  1985年   5篇
  1984年   1篇
  1983年   1篇
  1982年   3篇
  1980年   1篇
排序方式: 共有5878条查询结果,搜索用时 20 毫秒
61.
62.
63.
The recurrence of pressure ulcers (PrUs) and dehiscence of reconstructive flap have always been a problem. The present study aimed to evaluate the results of reconstructive flap surgeries in patients with spinal cord injury (SCI) having PrUs, using classic and modified flaps with improvisations to decrease wound dehiscence, flap necrosis and tension in flap. This is a prospective clinical study. The setting was a tertiary care centre in northern India. Thirty‐five patients with SCI having 37 stage III and IV PrUs. PrUs were treated using classic and modified flaps with improvisations. The outcome was evaluated using criteria of wound dehiscence, flap necrosis and recurrence. The results of flap surgery were excellent in 32 (86·48%) patients, good in 4 (10·81%) patients and poor in 1 (2·7%) patient. Partial flap necrosis (2·7%), low incidence of PrU recurrence rate at flap site (5·4%) and overall PrU recurrence (11·4%) were the complications observed. Improvisation of classic and modified techniques of flap surgeries along with reinforcement of general care principles of paraplegia can be effective in minimising complications often associated with PrU reconstructive surgery thus improving the ultimate outcome.  相似文献   
64.
65.
66.
Background: Extraction of the weak electrical activity of the “His Bundle” (HB) by noninvasive methods has not been very successful in the past. The study reassesses the use of signal averaged magnetocardiography (SAMCG), overcoming some of the limitations in earlier studies including in the signal averaging methodology. Methods: SAMCG on healthy subjects (14 male and 1 female) were performed using R‐peak as the fiducial point in all cases and also using QRS‐onset as the fiducial point in select cases. Results: A conspicuous feature (H) with a magnitude up to 200 femto Tesla (fT) attributed to the HB activity was observed in the PR segment at several spatial positions on the thorax, with onset at 35–50 ms before the QRS‐onset (V) in 15 out of 18 trials constituting 83% of cases studied. The QRS‐onset as the fiducial point resolved the feature better compared to the conventionally used R‐peak, especially in trials exhibiting spread in heart rate (HR). This is attributed to the fluctuations in QonRD (the time interval between QRS‐onset and R‐peak) compared to the temporal stability of the H‐V duration. Conclusions: SAMCG reveals a well‐resolved H feature. The double hump morphology of the feature extended at least up to a frequency of 150 Hz. The importance of the choice of QRS‐onset as the fiducial point is unequivocally demonstrated, illustrated by measurements on subjects exhibiting considerable heart rate variability. The latter has a general validity and should be applicable to SAECG as well.  相似文献   
67.
68.
69.
Conventional antimycobacterial screening involves CFU analysis, which poses a great challenge due to slow growth of mycobacteria. Recombinant strains carrying reporter genes under the influence of constitutive promoters allow rapid and wide screening of compounds but without revealing their modes of action. Reporter strains using pathway-specific promoters provide a better alternative but allow a limited screening of compounds interfering with only a particular metabolic pathway. This reduces these strains to merely a second-line screening system, as they fail to identify even the more potent compounds if they are not inhibiting the pathway of interest. In this study, we have generated a double recombinant Mycobacterium bovis BCG strain carrying firefly and Renilla luciferase genes as two reporters under the control of a constitutive and an inducible mycobacterial promoter. The presence of dual reporters allows simultaneous expression and analysis of two reporter enzymes within a single system. The expression profile of the firefly luciferase gene, rendered by a constitutive mycobacterial promoter, coincides with the decline in bacterial growth in response to a wide range of antimycobacterial drugs, while the enhanced expression of Renilla luciferase mirrors the selective induction of the reporter gene expression as a result of pathway-specific inhibition. Thus, the double recombinant strain allows the screening of both primary and rationally synthesized antimycobacterial compounds in a single assay. The inhibiting response of drugs was monitored with a dual-luciferase reporter assay which can be easily adapted in high-throughput mode.  相似文献   
70.
BackgroundHeart failure (HF) patients exhibit depression and executive function impairments that contribute to HF mortality. Using specialized magnetic resonance imaging (MRI) analysis procedures, brain changes appear in areas regulating these functions (mammillary bodies, hippocampi, and frontal cortex). However, specialized MRI procedures are not part of standard clinical assessment for HF (which is usually a visual evaluation), and it is unclear whether visual MRI examination can detect changes in these structures.Methods and ResultsUsing brain MRI, we visually examined the mammillary bodies and frontal cortex for global and hippocampi for global and regional tissue changes in 17 HF and 50 control subjects. Significantly global changes emerged in the right mammillary body (HF 1.18 ± 1.13 vs control 0.52 ± 0.74; P = .024), right hippocampus (HF 1.53 ± 0.94 vs control 0.80 ± 0.86; P = .005), and left frontal cortex (HF 1.76 ± 1.03 vs control 1.24 ± 0.77; P = .034). Comparison of the visual method with specialized MRI techniques corroborates right hippocampal and left frontal cortical, but not mammillary body, tissue changes.ConclusionsVisual examination of brain MRI can detect damage in HF in areas regulating depression and executive function, including the right hippocampus and left frontal cortex. Visual MRI assessment in HF may facilitate evaluation of injury to these structures and the assessment of the impact of potential treatments for this damage.  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