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   2755274篇
  免费   203715篇
  国内免费   5040篇
耳鼻咽喉   40440篇
儿科学   84672篇
妇产科学   74185篇
基础医学   391003篇
口腔科学   79597篇
临床医学   241891篇
内科学   535661篇
皮肤病学   57664篇
神经病学   217519篇
特种医学   108816篇
外国民族医学   887篇
外科学   432353篇
综合类   62284篇
现状与发展   5篇
一般理论   941篇
预防医学   207077篇
眼科学   64116篇
药学   208005篇
  7篇
中国医学   5442篇
肿瘤学   151464篇
  2018年   27334篇
  2016年   23154篇
  2015年   26565篇
  2014年   37375篇
  2013年   56812篇
  2012年   77508篇
  2011年   81827篇
  2010年   48579篇
  2009年   45843篇
  2008年   78063篇
  2007年   83792篇
  2006年   84228篇
  2005年   82182篇
  2004年   80221篇
  2003年   77356篇
  2002年   75680篇
  2001年   129597篇
  2000年   133928篇
  1999年   113696篇
  1998年   31524篇
  1997年   28115篇
  1996年   28230篇
  1995年   26632篇
  1994年   25006篇
  1993年   23332篇
  1992年   90552篇
  1991年   88178篇
  1990年   85940篇
  1989年   83124篇
  1988年   76815篇
  1987年   75378篇
  1986年   70694篇
  1985年   68252篇
  1984年   51133篇
  1983年   43477篇
  1982年   25505篇
  1981年   23143篇
  1980年   21166篇
  1979年   47571篇
  1978年   33170篇
  1977年   28399篇
  1976年   25801篇
  1975年   28204篇
  1974年   33822篇
  1973年   32443篇
  1972年   30428篇
  1971年   28330篇
  1970年   26849篇
  1969年   25305篇
  1968年   22880篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.

Background

The optimal noninvasive test (NIT) for patients with diabetes and stable symptoms of coronary artery disease (CAD) is unknown.

Objectives

The purpose of this study was to assess whether a diagnostic strategy based on coronary computed tomographic angiography (CTA) is superior to functional stress testing in reducing adverse cardiovascular (CV) outcomes (CV death or myocardial infarction [MI]) among symptomatic patients with diabetes.

Methods

PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) was a randomized trial evaluating an initial strategy of CTA versus functional testing in stable outpatients with symptoms suggestive of CAD. The study compared CV outcomes in patients with diabetes (n = 1,908 [21%]) and without diabetes (n = 7,058 [79%]) based on their randomization to CTA or functional testing.

Results

Patients with diabetes (vs. without) were similar in age (median 61 years vs. 60 years) and sex (female 54% vs. 52%) but had a greater burden of CV comorbidities. Patients with diabetes who underwent CTA had a lower risk of CV death/MI compared with functional stress testing (CTA: 1.1% [10 of 936] vs. stress testing: 2.6% [25 of 972]; adjusted hazard ratio: 0.38; 95% confidence interval: 0.18 to 0.79; p = 0.01). There was no significant difference in nondiabetic patients (CTA: 1.4% [50 of 3,564] vs. stress testing: 1.3% [45 of 3,494]; adjusted hazard ratio: 1.03; 95% confidence interval: 0.69 to 1.54; p = 0.887; interaction term for diabetes p value = 0.02).

Conclusions

In diabetic patients presenting with stable chest pain, a CTA strategy resulted in fewer adverse CV outcomes than a functional testing strategy. CTA may be considered as the initial diagnostic strategy in this subgroup. (PROspective Multicenter Imaging Study for Evaluation of Chest Pain [PROMISE]; NCT01174550)  相似文献   
12.
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.

Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.

Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.

Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality.  相似文献   
13.
14.
15.
Purpose/aim: To focus on current aspects of primary thyroid lymphoma (PTL), which is a rare clinical entity usually manifested by a rapidly growing mass in the neck that can cause pressure symptoms.

Materials and Methods: Relevant papers in PubMed published through June 2017 were selected to track updated information about PTL with an emphasis on diagnosis and novel therapeutic management.

Results: The most frequent cases include non-Hodgkin lymphoma derived from B-cells, mainly diffuse large B-cell lymphoma (DLBCL) followed by mucosa-associated lymphoid tissue (MALT) lymphoma or a mixed type. Other subtypes are less common. Lymphomas derived from T-cells and Hodgkin lymphomas are extremely rare. Hashimoto's autoimmune thyroiditis has been implicated as a risk factor for lymphoma. At the molecular level, the Wnt5a protein and its receptor Ror2 are involved in the course of the disease. Ultrasonography, fine needle aspiration (FNA) biopsy, and core or open biopsy combined with new diagnostic facilities contribute to an accurate diagnosis. An increased potential exists for a cure without the need for a radical surgical procedure. Modern chemoradiation therapy plus the monoclonal antibody rituximab, which acts against CD20, have limited the need for surgical interventions and provide an excellent outcome in most cases. However, some cases have resulted in treatment failure or recurrence.

Conclusions: A multidisciplinary approach must be used to define the management policy in each case. Future efforts by researchers are likely to be focused on the molecular level.  相似文献   

16.

Background

Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain.

Methods

We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male).

Results

Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS2 score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians.

Conclusions

Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS2 scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation.  相似文献   
17.
18.

Background and aims

Since accelerated atherosclerosis has been reported in systemic lupus erythematosus (SLE), predictive biomarkers of cardiovascular disease (CVD) are needed. Among non-traditional risk factors, bone mineral density (BMD) has been related to CVD. However, its role in SLE remains controversial. This study aims to analyze the associations of subclinical atherosclerosis with traditional and non-traditional CV risk factors.

Methods and results

In a cross-sectional study, atherosclerosis burden was compared between 112 female SLE patients and 31 controls. Plaque number and carotid intima-media wall thickness (cIMT) were assessed by ultrasonography. In a retrospective study, BMD determinations obtained 5-years before the ultrasonography assessment were analyzed in a subgroup of 62 patients. Plaque frequency was increased in SLE, even in patients without CV events or carotid wall thickening. cIMT was increased in patients with CVD, positively correlated with body mass index (BMI). Interestingly, a paradoxical effect of BMI on carotid parameters was observed. Whereas underweight patients (BMI < 20) showed increased prevalence of carotid plaques with low cIMT, those with BMI > 30 showed higher cIMT and plaque burden. Overweight patients (25 < BMI<30) exhibited both elevated cIMT and plaque number. BMI was an independent predictor of BMD. In our retrospective study, patients with either clinical or subclinical CVD exhibited lower BMD levels than their CV-free counterparts. A low lumbar spine BMD independently predicted CVD development after adjusting for confounders.

Conclusion

SLE was associated with a higher subclinical atherosclerosis burden, a bimodal effect being observed for BMI. Decreased BMD can be a CV risk biomarker in SLE.  相似文献   
19.
Bernard–Soulier syndrome (BSS) is a rare autosomal recessively inherited bleeding disorder. Pregnancy in patients with BSS is characterized by ante‐, intra‐, or postpartum haemorrhage, which may be delayed and severe. There is no consensus in the management of BSS in pregnancy and so far only 16 pregnancies in nine patients have been described. We report a further three pregnancies in two women with the syndrome. We also outline our management of pregnant patients with BSS.  相似文献   
20.
Conclusion  Several quality-control measures take place before (patient and camera preparation) and during SPECT acquisition to achieve high-quality images. Not uncommonly, technologists and physicians are left with suboptimal images that have to be addressed to reach the “right answer” for patient diagnosis and hence management. In many cases patients may be reimaged, especially if the problem is detected early, but in other cases either the patient has left the nuclear laboratory or there is an inevitable problem that, even with reimaging, will not be resolved. In these situations the technologist and physician have to seek the available techniques to obtain the best images possible. These resources are discussed in this issue as an aid in quality control to obtain the best possible images.  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