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   4262篇
  免费   465篇
  国内免费   101篇
耳鼻咽喉   80篇
儿科学   62篇
妇产科学   173篇
基础医学   244篇
口腔科学   58篇
临床医学   364篇
内科学   529篇
皮肤病学   61篇
神经病学   86篇
特种医学   340篇
外国民族医学   2篇
外科学   956篇
综合类   423篇
预防医学   98篇
眼科学   28篇
药学   100篇
  6篇
中国医学   68篇
肿瘤学   1150篇
  2024年   12篇
  2023年   81篇
  2022年   135篇
  2021年   189篇
  2020年   204篇
  2019年   207篇
  2018年   184篇
  2017年   201篇
  2016年   195篇
  2015年   193篇
  2014年   286篇
  2013年   239篇
  2012年   278篇
  2011年   275篇
  2010年   219篇
  2009年   212篇
  2008年   224篇
  2007年   238篇
  2006年   223篇
  2005年   162篇
  2004年   117篇
  2003年   117篇
  2002年   105篇
  2001年   84篇
  2000年   66篇
  1999年   64篇
  1998年   52篇
  1997年   30篇
  1996年   32篇
  1995年   23篇
  1994年   28篇
  1993年   15篇
  1992年   10篇
  1991年   17篇
  1990年   13篇
  1989年   12篇
  1988年   13篇
  1987年   10篇
  1986年   7篇
  1985年   9篇
  1984年   8篇
  1983年   4篇
  1982年   8篇
  1981年   9篇
  1980年   5篇
  1979年   3篇
  1978年   3篇
  1976年   2篇
  1975年   3篇
  1972年   1篇
排序方式: 共有4828条查询结果,搜索用时 78 毫秒
81.
82.
PURPOSE: Current American Joint Committee on Cancer and the Union Internationale Contre le Cancer TNM classification disregards location of positive nodes, discontinuing N3 category, which constitutes a major modification to 1987 version. This study was designed to assess the impact of the recategorization of former N3 cases and the reliability of the current N1-N2 subcategorization of Stage III patients. METHODS: Prospectively collected data from 1,391 patients (55.8 percent males; median age, 64 (range, 21–97) years), operated on with curative intent between 1980 and 1999, were analyzed. The median follow-up was 60 (interquartile range, 27–97) months with 129 cases lost to follow-up. RESULTS: Of positive node cases, 25.3 percent were former N3. Among them, 30.5 percent migrated to the N1 group and 69.5 percent to the N2 group. The proportions of former N3 cases in N1 and N2 groups were 12.5 percent and 46.1 percent, respectively (P < 0.001). Node-positive patients had an actuarial five-year survival rate of 56.7 percent (95 percent confidence interval, 53–59), with a significant difference between N1/N2 categories (63.6 vs. 44.1 percent, respectively; P < 0.001). Although apical node involvement and more than three positive nodes were associated with poorer outcomes in univariate analysis, only the number of positive nodes had independent association (hazard ratio, 1.6 (range, 1.2–2.2); P < 0.001). Integration of former N3 cases did not modify outcomes. CONCLUSIONS: The recategorization of former N3 involved a high proportion of positive node cases. Current N1/N2 categories clearly defined different outcomes and were not modified by the integration of former N3.  相似文献   
83.
Background: T1 mapping allows quantitative assessment of “diffuse” deposition of amyloid protein in the myocardium. Early detection of cardiac involvement and potential prognostic improvement could benefit patients with AL amyloidosis.

Objectives: This study aims to evaluate the regional variation of amyloid infiltration in the left ventricle and the prognostic value of T1 mapping in patients with AL amyloidosis.

Methods: We prospectively enrolled 77 patients with AL amyloidosis who underwent cardiac magnetic resonance on a 3.0-T scanner. Native T1 and extracellular volume (ECV) were quantitated on the basal, mid, and apical levels of the left ventricle. Late gadolinium enhancement (LGE) pattern (no or non-specific LGE, sub-endocardial LGE, and transmural LGE) was also assessed. Forty healthy subjects served as controls. The primary end point was all-cause mortality.

Results: Basal ECV (26.9?±?2.8% versus 31.1?±?4.9%, p?<?.001) were lower than apical ECV in the healthy controls; however, basal ECV (60.6?±?11.5% versus 53.0?±?9.6%, p?=?.003) were significantly higher than apical ECV in patients with transmural LGE. During the follow-up period (median duration, 28?months; 25th–75th percentile, 13.5–38.0?months), 46 patients died. Basal ECV has the largest area under the curve of 0.845 (95% CI, 0.747–0.917) to predict all-cause mortality. Multivariable Cox analysis indicated that basal ECV was an independent prognostic factor and showed incremental prognostic value beyond NYHA class, Mayo stage, and LGE pattern.

Conclusion: We demonstrated that T1 mapping may have the potential to detect a characteristic amyloid deposition with a decreasing gradient from base to apex. Furthermore, myocardial ECV indicated that basal amyloid infiltration provided robust and incremental prognostic value in patients with AL amyloidosis.  相似文献   

84.

Background

The World Wide Web allows access to patient/care partner perspectives on the lived experience of dementia. We were interested in how symptoms that care partners target for tracking relate to dementia stage, and whether dementia could be staged using only these online profiles of targeted symptoms.

Objectives

To use clinical data where the dementia stage is known to develop a model that classifies an individual’s stage of dementia based on their symptom profile and to apply this model to classify dementia stages for subjects from a Web-based dataset.

Methods

An Artificial Neural Network (ANN) was used to identify the relationships between the dementia stages and individualized profiles of people with dementia obtained from the 60-item SymptomGuide (SG). The clinic-based training dataset (n=320), with known dementia stages, was used to create an ANN model for classifying stages in Web-based users (n=1930).

Results

The ANN model was trained in 66% of the 320 Memory Clinic patients, with the remaining 34% used to test its accuracy in classification. Training and testing staging distributions were not significantly different. In the 1930 Web-based profiles, 309 people (16%) were classified as having mild cognitive impairment, 36% as mild dementia, 29% as moderate, and 19% as severe. In both the clinical and Web-based symptom profiles, most symptoms became more common as the stage of dementia worsened (eg, mean 5.6 SD 5.9 symptoms in the MCI group versus 11.9 SD 11.3 in the severe). Overall, Web profiles recorded more symptoms (mean 7.1 SD 8.0) than did clinic ones (mean 5.5 SD 1.8). Even so, symptom profiles were relatively similar between the Web-based and clinical datasets.

Conclusion

Symptoms targeted for online tracking by care partners of people with dementia can be used to stage dementia. Even so, caution is needed to assure the validity of data collected online as the current staging algorithm should be seen as an initial step.  相似文献   
85.
黎燕  林燕凤  梁彦 《全科护理》2021,19(8):1061-1064
目的:观察护理服务精准加载法在永久性肠造口病人中的应用效果。方法:选择收治于我院接受低位直肠癌永久性肠造口者88例为研究样本,以随机数字表法分为试验组和对照组各44例,对照组按永久性肠造口常规护理执行,试验组接受护理服务精准加载法干预,对两组干预后的各观察指标进行比较。结果:试验组永久性肠造口者干预后的肠造口自我效能评分和自我护理能力评分显著高于对照组,肠造口相关并发症发生率显著低于对照组(P<0.05)。结论:采用护理服务精准加载法对永久性肠造口病人施加干预,可显著提升该类病人肠造口自我效能与自护水平,降低肠造口相关并发症发生率。  相似文献   
86.
The albumin:globulin (A:G) ratio, adult comorbidity evaluation 27 (ACE-27), and TMN staging have been shown to be strong predictive indicators of the survival of patients with many types of tumours. We have investigated the prognostic value of pretreatment based on the A:G ratio combined with TMN staging and ACE-27 in patients with squamous cell carcinoma (SCC) of the maxillary sinus. We studied 196 patients, and the prognostic value was explored by univariate and multivariate Cox’s hazards analysis. Multivariate analyses suggested that pretreatment A:G ratio was independently associated with overall survival (hazard ratio (HR) 1.542, 95% CI 1.219 to 1.991, p = 0.002); disease-specific survival, (HR 1.499, 95% CI 1.197 to 1.842, p = 0.001); and disease-free survival (HR 1.452, 95% CI 1.207 to 1.834, p < 0.001). Additional prognostic factors shown in the survival analyses included ACE-27, pathological T stage, and pathological N stage. Pretreatment A:G ratio combined with ACE-27 and TMN staging were powerful prognostic indicators of outcome in patients with SCC of the maxillary sinus, which has potentially important ramifications for stratification of the disease in the future.  相似文献   
87.
正确的植入位点对于种植修复的长期稳定有效十分重要,为提高植入的精准度,临床上越来越多地使用外科导板、手术导航等来控制位点,引导种植体的植入。但是一方面由于这类数字化手段存在过程繁琐、费用较高等问题,大量的病例仍然是由自由手植入的;另一方面,在术前、术中、术后缺乏快速实用的实测位点的方法,不少病例只有术后锥形束CT检查时才发现位点不良,改正位点的代价不小。本文介绍一种适用于各类种植系统的全程植入位点的实测方法及其引导的精准植入技术。本技术由实测尺子引导,包括测量尺和术中定位尺两部分。术前使用测量尺测量术区三维空间,根据实测数据结合锥形束CT数据进行种植方案和数量引导设计,术中用实测尺子引导全程种植,兼顾实测核查。这种方法实现了植入手术从术前空间分析、术中精准植入引导及术后位点实测评价的全程可量化,可全程及时调整位点,提高了植入精度,是一项适宜推广的牙种植实用技术。  相似文献   
88.
目的:探讨MRI平扫结合扩散加权成像(DWI)在直肠癌中的临床应用价值.方法:对28例直肠癌患者行MRI平扫及DWI检查,评价肿瘤形态、T分期、淋巴结转移、环周切缘(CRM)状态、肿瘤下缘距肛缘的距离,并与术后病理结果进行对照.MRI与病理对T分期、N分期及环周切缘受累评估的一致性采用Kappa检验.结果:MRI平扫及DWI能准确显示肿瘤的部位及形态.MRI平扫结合DWI对28例直肠癌T分期总的诊断符合率为78.57%(22/28),T1~T2期、T3期、T4期的诊断符合率分别为85.71%、78.57%、92.86%,MRI与病理对T分期的诊断具有较高的一致性(Kappa值=0.656).MRI平扫结合DWI对判断N分期的符合率为71.43% (20/28),判断淋巴结转移的敏感度为66.67%(6/9),特异度为73.68%(14/19),MRI与病理对N分期的诊断具有中度一致性(Kappa值=0.489).MRI判定CRM状态的总体符合率为85.71% (24/28),敏感度为90.90%(10/11),特异度为82.35%(14/17),阳性预测值为76.92%(10/13),阴性预测值为93.33%(14/15),MRI与病理对环周切缘受累的评估具有较高的一致性(Kappa值=0.710).MRI矢状面图像能测量18例下段直肠癌肿瘤下缘距肛缘的曲线距离.结论:MRI平扫结合DWI对直肠癌、T分期、环周切缘状态的判断及肿瘤下缘距肛缘的距离的测量有重要临床价值.  相似文献   
89.
90.
Preoperatively evaluating the resectability of pancreatobiliary cancers is difficult. The aim of this study was to investigate the benefit of staging laparoscopy in unresectable pancreatobiliary cancers. Between 2010 and 2013, 25 patients with pancreatobiliary cancers underwent staging laparoscopy after conventional tumor staging; they were compared with 10 patients who had unresectable or metastatic tumors that were found during laparotomy. Staging laparoscopy did not show unresectable factors in 11 patients, and resections were performed in these patients. Unresectable factors were found in other 14 patients who underwent staging laparoscopy. In these patients, chemotherapy was started after median postoperative day 3 (range, 2–10 days). This period was significantly longer in patients who received unnecessary laparotomy; chemotherapy was started after median postoperative day 11 (range, 6–15 days). These results suggest that staging laparoscopy, while avoiding laparotomy with unsuccessful resection, can lead to rapid induction of chemotherapy for unresectable pancreatobiliary cancers.  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