首页 | 官方网站   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   5541篇
  免费   393篇
  国内免费   9篇
医药卫生   5943篇
  2024年   12篇
  2023年   69篇
  2022年   79篇
  2021年   212篇
  2020年   124篇
  2019年   187篇
  2018年   222篇
  2017年   159篇
  2016年   174篇
  2015年   168篇
  2014年   212篇
  2013年   310篇
  2012年   436篇
  2011年   490篇
  2010年   231篇
  2009年   260篇
  2008年   373篇
  2007年   426篇
  2006年   337篇
  2005年   342篇
  2004年   265篇
  2003年   277篇
  2002年   228篇
  2001年   37篇
  2000年   24篇
  1999年   38篇
  1998年   36篇
  1997年   24篇
  1996年   23篇
  1995年   18篇
  1994年   13篇
  1993年   11篇
  1992年   6篇
  1991年   13篇
  1990年   5篇
  1989年   25篇
  1988年   6篇
  1987年   2篇
  1986年   2篇
  1985年   6篇
  1984年   10篇
  1983年   4篇
  1982年   9篇
  1981年   7篇
  1980年   8篇
  1979年   4篇
  1978年   2篇
  1977年   3篇
  1976年   2篇
  1968年   3篇
排序方式: 共有5943条查询结果,搜索用时 15 毫秒
61.
Bacterial vaginosis (BV) is the most common gynecological infection in the United States. Diagnosis based on Amsel''s criteria can be challenging and can be aided by laboratory-based testing. A standard method for diagnosis in research studies is enumeration of bacterial morphotypes of a Gram-stained vaginal smear (i.e., Nugent scoring). However, this technique is subjective, requires specialized training, and is not widely available. Therefore, a highly accurate molecular assay for the diagnosis of BV would be of great utility. We analyzed 385 vaginal specimens collected prospectively from subjects who were evaluated for BV by clinical signs and Nugent scoring. We analyzed quantitative real-time PCR (qPCR) assays on DNA extracted from these specimens to quantify nine organisms associated with vaginal health or disease: Gardnerella vaginalis, Atopobium vaginae, BV-associated bacteria 2 (BVAB2, an uncultured member of the order Clostridiales), Megasphaera phylotype 1 or 2, Lactobacillus iners, Lactobacillus crispatus, Lactobacillus gasseri, and Lactobacillus jensenii. We generated a logistic regression model that identified G. vaginalis, A. vaginae, and Megasphaera phylotypes 1 and 2 as the organisms for which quantification provided the most accurate diagnosis of symptomatic BV, as defined by Amsel''s criteria and Nugent scoring, with 92% sensitivity, 95% specificity, 94% positive predictive value, and 94% negative predictive value. The inclusion of Lactobacillus spp. did not contribute sufficiently to the quantitative model for symptomatic BV detection. This molecular assay is a highly accurate laboratory tool to assist in the diagnosis of symptomatic BV.  相似文献   
62.
63.
64.
A total of 779 patients operated on for vestibular schwannoma mostly by the translabyrinthine approach in Denmark during the period 1976-2000 answered a questionnaire about various postoperative consequences. In this paper we describe the patients' facial function evaluated by professionals one year postoperatively and self-evaluated by each patient according to the House-Brackmann scale at the time of the questionnaire. The patients' self-evaluation was more pessimistic than that of the professionals with 26% reporting House-Brackmann grade IV-VI, compared with 20%. One hundred and seventeen (15%) of 779 patients considered their facial palsy to be a big problem and 125 patients (16%) were interested in surgical treatment for the sequelae of facial palsy. Seventy-eight (10%) had already had some kind of operation, usually the VII-XII coaptation. Thirty-three of 61 patients who had already been operated on for facial palsy were interested in further surgical treatment. One hundred and ninety-five patients (25%) had some kind of operation on the eye, mostly (88%) a tarsorrhaphy. Reanimation procedures such as a palpebral gold weight or a spring, apparently still have a small place in Denmark. In conclusion, there seem to be a considerable and unmet need for surgical reanimation of facial function in patients with facial palsy after operations for vestibular schwannoma in Denmark.  相似文献   
65.

Background

For patients with hepatocellular carcinoma (HCC) not eligible for surgical resection, radiofrequency ablation (RFA) is a promising technique that reduces the risk of disease progression.

Objectives

To evaluate whether the trend of image guidance for RFA is moving toward the more expensive computed tomography (CT) technology and to determine the clinical benefits of CT guidance over the ultrasound (US) guidance.

Methods

A cohort of 463 patients was identified from the Surveillance, Epidemiology, and End Results and Medicare–linked database. The temporal trends in use of image guidance were assessed using the Cochrane–Armitage test. The associations between modality of image guidance and survival, complications, and costs were assessed using the Cox regression model, the logistic regression model, and the generalized linear model, respectively.

Results

The use of CT-guided RFA increased sharply, from 20.7% in 2002 to 75.9% in 2011. Compared with CT-guided RFA, those who received US-guided RFA had comparable risk of periprocedural and delayed postprocedural complications. Stratified analyses by tumor size also showed no statistically significant difference. In adjusted survival analysis, no statistically significant difference was observed in overall and cancer-specific survival. Nevertheless, the cost of CT-guided RFA ($2847) was higher than that of US-guided RFA ($1862).

Conclusions

Despite its rapid adoption over time, CT-guided RFA incurred higher procedural costs than US-guided RFA but did not significantly improve postprocedural complications and survival. Echoing the American Board of Internal Medicine’s Choosing Wisely campaign and the American Society of Clinical Oncology’s Value of Cancer Care initiative, findings from our study call for critical evaluation of whether CT-guided RFA provides high-value care for patients with HCC.  相似文献   
66.
67.
68.
The cerebral metabolic rate of oxygen (CMRO2) is the rate of oxygen consumption by the brain, and is thought to be a direct index of energy homeostasis and brain health. However, in vivo measurement of CMRO2 is challenging, in particular for the neonatal population, in whom conventional radiotracer methods are not applicable because of safety concerns. In this study, we propose a method to quantify global CMRO2 in neonates based on arteriovenous differences in oxygen content, and employ separate measurements of oxygenation and cerebral blood flow (CBF) parameters. Specifically, arterial and venous oxygenation levels were determined with pulse oximetry and the novel T2 relaxation under spin tagging (TRUST) MRI, respectively. Global CBF was measured with phase contrast (PC) flow velocity MRI. The proposed method was implemented on a standard 3‐T MRI scanner without the need for any exogenous tracers, and the total scan duration was less than 5 min. We demonstrated the feasibility of this method in 12 healthy neonates within an age range of 35–42 gestational weeks. CMRO2 values were successfully obtained from 10 neonates. It was found that the average CMRO2 in this age range was 38.3 ± 17.7 µmol/100 g/min and was positively correlated with age (p = 0.007; slope, 5.2 µmol/100 g/min per week), although the highest CMRO2 value in this age range was still less than half of the adult level. Test–retest studies showed a coefficient of variation of 5.8 ± 2.2% between repeated CMRO2 measurements. In addition, given the highly variable blood flow velocity within this age range, it is recommended that the TRUST labeling thickness and position should be determined on a subject‐by‐subject basis, and an automatic algorithm was developed for this purpose. Although this method provides a global CMRO2 measure only, the clinical significance of an energy consumption marker and the convenience of this technique may make it a useful tool in the functional assessment of the neonatal population. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
69.
70.
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-23

京公网安备 11010802026262号