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   1591232篇
  免费   133520篇
  国内免费   2561篇
耳鼻咽喉   21625篇
儿科学   52805篇
妇产科学   46271篇
基础医学   226023篇
口腔科学   47167篇
临床医学   140144篇
内科学   312156篇
皮肤病学   34056篇
神经病学   129229篇
特种医学   64714篇
外国民族医学   474篇
外科学   243262篇
综合类   39673篇
现状与发展   3篇
一般理论   544篇
预防医学   122115篇
眼科学   36317篇
药学   120942篇
  2篇
中国医学   2877篇
肿瘤学   86914篇
  2018年   14771篇
  2016年   12909篇
  2015年   15037篇
  2014年   20667篇
  2013年   31380篇
  2012年   42596篇
  2011年   44789篇
  2010年   26350篇
  2009年   25326篇
  2008年   43028篇
  2007年   45289篇
  2006年   46075篇
  2005年   44730篇
  2004年   44114篇
  2003年   42106篇
  2002年   41231篇
  2001年   75602篇
  2000年   78170篇
  1999年   66004篇
  1998年   16703篇
  1997年   15343篇
  1996年   15287篇
  1995年   15947篇
  1994年   14990篇
  1993年   14151篇
  1992年   55381篇
  1991年   53780篇
  1990年   52551篇
  1989年   50809篇
  1988年   47197篇
  1987年   46550篇
  1986年   44267篇
  1985年   42836篇
  1984年   32000篇
  1983年   27536篇
  1982年   16096篇
  1981年   14383篇
  1980年   13495篇
  1979年   30417篇
  1978年   21030篇
  1977年   17695篇
  1976年   16652篇
  1975年   17519篇
  1974年   21455篇
  1973年   20646篇
  1972年   18846篇
  1971年   17755篇
  1970年   16275篇
  1969年   15252篇
  1968年   13937篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
BACKGROUND AND PURPOSE:Collateral status and thrombus length have been independently associated with functional outcome in patients with acute ischemic stroke. It has been suggested that thrombus length would influence functional outcome via interaction with the collateral circulation. We investigated the individual and combined effects of thrombus length assessed by the clot burden score and collateral status assessed by a FLAIR vascular hyperintensity–ASPECTS rating system on functional outcome (mRS).MATERIALS AND METHODS:Patients with anterior circulation acute ischemic stroke due to large-vessel occlusion from the ASTER and THRACE trials treated with endovascular thrombectomy were pooled. The clot burden score and FLAIR vascular hyperintensity score were determined on MR imaging obtained before endovascular thrombectomy. Favorable outcome was defined as an mRS score of 0–2 at 90 days. Association of the clot burden score and the FLAIR vascular hyperintensity score with favorable outcome (individual effect and interaction) was examined using logistic regression models.RESULTS:Of the 326 patients treated by endovascular thrombectomy with both the clot burden score and FLAIR vascular hyperintensity assessment, favorable outcome was observed in 165 (51%). The rate of favorable outcome increased with clot burden score (smaller clots) and FLAIR vascular hyperintensity (better collaterals) values. The association between clot burden score and functional outcome was significantly modified by the FLAIR vascular hyperintensity score, and this association was stronger in patients with good collaterals, with an adjusted OR = 6.15 (95% CI, 1.03–36.81).CONCLUSIONS:The association between the clot burden score and functional outcome varied for different collateral scores. The FLAIR vascular hyperintensity score might be a valuable prognostic factor, especially when contrast-based vascular imaging is not available.

Therapeutic reperfusion with endovascular thrombectomy (EVT) is consistently associated with a better long-term functional outcome in anterior circulation acute ischemic stroke (AIS).1 Early reperfusion is the mainstay of therapy because it strongly predicts functional outcome.2 Many factors impact clinical outcomes, including the extent of clot and collateral supply.37The clot burden score (CBS) assessed by the T2* MR imaging sequence (T2*-CBS), which was adapted from the CTA-CBS,8 has been used to assess the extent of the clot9 and has been independently associated with functional outcome in patients undergoing EVT.10Good collaterals have been related to better clinical outcome through 2 distinct mechanisms. First, collaterals are thought to contribute to prolonged penumbra sustenance.11,12 Second, good retrograde collateral filling beyond the occlusion could promote successful reperfusion by providing more access to thrombolytics at the distal end of the clot and robust collaterals dissolving clot fragments in the distal vasculature.13,14 The Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration analysis suggested a benefit with EVT across all strata of collateral circulation status;15 however, patients with poor collaterals are less likely to benefit from EVT than those with better collaterals.Most interesting, FLAIR vascular hyperintensity (FVH) on baseline MR imaging could indicate the formation of a leptomeningeal collateral circulation and serve as a prognostic marker for patients with AIS.16-18 Both collaterals and the CBS were separately associated with functional outcome in patients undergoing EVT,10,16 but their combined effect regarding clinical outcome is still poorly understood and has been assessed and quantified only with CTA or contrast-enhanced MRA in patients with AIS.14,15 Furthermore, the lack of adjustment for possible confounders because of the small number of patients with very low collateral scores might also have influenced results in these studies.The purpose of this study was to determine whether there is an association between the CBS and FVH score and whether the association between the CBS and functional outcome is modified by the FVH score for patients who were treated by EVT for large-vessel occlusion within the framework of the Contact Aspiration versus Stent Retriever for Successful Revascularization (ASTER) and the THRombectomie des Artères CErebrales (THRACE) randomized trials.19,20  相似文献   
72.
To explore patients’ experiences of orthognathic treatment for facial asymmetry and their adaptation to facial changes after surgery, we did a qualitative, cross-sectional study of patients after treatment for non-cleft asymmetry at two UK sites. A total of 15 patients aged 19-40 years were approached after being identified using patient databases and clinical notes. Individual and photo-elicitation interviews were conducted covering experiences prior to treatment, during treatment, and after surgery. Interviews were transcribed and thematic narrative analysis undertaken. Participants were largely positive about their orthognathic treatment. The following themes were identified: preoperative (becoming aware, negative impacts of asymmetry, committing to treatment, establishing expectations), pre-surgery orthodontics and inpatient experiences (challenges and coping strategies, preparedness, support, and shared experiences); and postoperative (surgery as ‘worth it’, positive impacts of treatment, adapting to facial change). Undergoing orthognathic surgery was portrayed as a journey involving recognisable narratives (treatment unfinished, threat of liminality, treatment as resolution, and treatment as transformation). Patients’ experiences of facial asymmetry are associated with feeling ‘abnormal’, and negative impacts, and orthognathic treatment for facial asymmetry is worthwhile. Having the feeling that something is ‘wrong’ legitimised by clinicians allows patients access to a recognisable treatment narrative (resolution). Orthognathic treatment is also described as transformation from ‘normal abnormality’ to being ‘normal’. Nevertheless, the associated challenges can be frustrating, particularly if resolution is hard to envisage. Further psychological input could help patients cope with these challenges and the complex process of adapting to facial change.  相似文献   
73.
The first COVID-19 vaccination was given in December 2020 and there is an effort to vaccinate the international population on a massive scale. Common side effects from the vaccine include headache and tiredness. Regional lymphadenopathy has been described in relation to other vaccines. We describe two cases of supraclavicular reactive lymphadenopathy presenting in patients who had the COVID vaccination in the ipsilateral arm. Awareness of this diagnosis is important for patients presenting to the neck lump clinic.  相似文献   
74.
Throat packs are commonly used in maxillofacial surgeries. However, the evidence to support the benefits of their use is controversial. The aim of this study was to evaluate the effectiveness of throat packs in preventing postoperative nausea and vomiting, and their influence on the incidence of sore throat and dysphagia in patients undergoing orthognathic surgery. This was a prospective double-blind randomized study with 54 patients, who were randomized to two groups: with throat pack (n = 27) and without throat pack (n = 27). Fifty patients (25 in each group) were included in the analysis; 66% female and 34% male, mean age 29.44 ± 8.53 years. Postoperative nausea and vomiting (Kortilla scale), sore throat (visual analogue scale), and dysphagia were evaluated. Statistically significant differences in favour of the without-pack group were found for the variables throat pain at 24 hours (P = 0.002) and dysphagia at 2 hours (P = 0.007) and 24 hours (P < 0.001). There was no difference between the groups regarding postoperative nausea and vomiting (P = 1.00). The results of this study indicate that throat packs as utilized here do not prevent postoperative nausea and vomiting and are associated with worse sore throats and postoperative dysphagia.  相似文献   
75.
76.
Monitoring vascular perfusion of transferred tissue is essential in reconstructive surgery to recognize early flap failure. The aim of this study was to evaluate the ability of a digital surface scanner to detect vascular perfusion disorders through the monitoring of skin colour changes. A total of 160 surface scans of the forearm skin were performed with a TRIOS 3D scanner. Vascular compromise was simulated at different time-points by intermittent occlusion of the blood supply to the forearm skin (first the arterial blood supply and then the venous blood supply). Skin colour changes were examined according to the hue, saturation, and value colour scale. Colour differences were analysed with a paired t-test. Significant differences were observed between the colour of the normal skin and that of the vascular compromised skin (P < 0.01). The surface scanner could distinguish between arterial occlusion and venous congestion (P < 0.01). A digital surface scan is an objective, non-invasive tool to detect early vascular perfusion disorders of the skin.  相似文献   
77.
The aim of this study was to analyse the effect of body mass index (BMI), both low and high values, on the perioperative complication rate in patients with oral squamous cell carcinoma (OSCC). The medical records of 259 patients operated between 2014 and 2017 for OSCC were reviewed. Univariate and multivariate analyses were performed. Sixty of the 259 patients developed 87 complications. Low or high BMI was not associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade. Low BMI, American Society of Anesthesiologists score 2 and 3, a longer operating time, and increased blood loss were associated with a longer hospital stay. Low BMI was associated with a longer hospital stay. Neither low nor high BMI was associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade.  相似文献   
78.
The selection and implementation of a plan for maxillary surgery is of the utmost importance in achieving the desired outcome for the patient undergoing two-jaw orthognathic surgery. Some splint-based and splintless methods, accompanied by computer-assisted techniques, are helpful in improving surgical plan implementation. However, randomized controlled trials focused on this procedure are lacking. This study included 61 patients who underwent bimaxillary surgeries. The patients were randomly assigned to a conventional resin occlusal splint (CROS) group, a digital occlusal splint (DOS) group, or a digital templates (DT) group, in a 1:1:1 ratio. The mean linear distance between the planned and actual postoperative positions of eight selected points on the surfaces of the maxillary teeth was selected as the outcome measure. The distance was significantly smaller in the DT group (1.17 ± 0.66 mm) when compared to both the CROS group (2.55 ± 0.95 mm, P < 0.05) and DOS group (2.15 ± 1.12 mm, P < 0.05). However, the difference between the CROS group and DOS group was not statistically significant. These findings indicate that using digital templates results in the best performance in transferring the surgical plan to the operation environment as compared to the other two types of splints. This suggests that the application of digital templates could provide a reliable treatment option.  相似文献   
79.
80.
ObjectivesAlthough survival after a cancer diagnosis has improved considerably over the past 20 years, little is known about trends in health-related quality-of-life (HRQOL) for older prostate, breast, and lung cancer survivors.MethodsUsing a population-based registry with longitudinal patient reported outcomes (the National Cancer Institute Surveillance, Epidemiology and End Results database linked to Medicare Health Outcomes Survey), we analyzed Medicare Advantage patients diagnosed with cancer during 1998–2011, who completed surveys regarding HRQOL through 2013. ‘Early Era’ patients were treated during 1998–2003; ‘Late Era’ patients were treated during 2006–2011. After propensity score matching, post-diagnosis changes in health utility (HU), Physical Component Summary (PCS) and Mental Component Summary (MCS) scores were calculated and compared between the two eras.ResultWe identified 208 older patients with prostate, 276 with breast and 76 with lung cancer who were treated in the ‘Early Era’ and matched to equal numbers in the ‘Late Era’. Mean age of patients in early and late era was 72 and 73 years, respectively. The mean post-diagnosis decline in health utility for patients treated in the ‘Late Era’ was not significantly different from the ‘Early Era’ for any cancer (Prostate [early vs. late]: ?0.06 vs. -0.03, p = .09; Breast: ?0.03 vs. ?0.04, p = .65; Lung: ?0.07 vs. ?0.07, p = .95); nor for Physical Component Summary or Mental Component Summary scores.ConclusionOlder patients treated for prostate, breast or lung cancer in the later era reported similar outcomes of changes in HRQOL compared to earlier era patients.  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