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   1049篇
  免费   90篇
  国内免费   4篇
耳鼻咽喉   8篇
儿科学   40篇
妇产科学   58篇
基础医学   185篇
口腔科学   10篇
临床医学   84篇
内科学   193篇
皮肤病学   27篇
神经病学   95篇
特种医学   32篇
外科学   109篇
综合类   2篇
预防医学   86篇
眼科学   12篇
药学   95篇
肿瘤学   107篇
  2024年   2篇
  2023年   5篇
  2022年   15篇
  2021年   29篇
  2020年   27篇
  2019年   41篇
  2018年   32篇
  2017年   34篇
  2016年   42篇
  2015年   28篇
  2014年   51篇
  2013年   68篇
  2012年   94篇
  2011年   80篇
  2010年   44篇
  2009年   54篇
  2008年   78篇
  2007年   86篇
  2006年   59篇
  2005年   64篇
  2004年   43篇
  2003年   38篇
  2002年   30篇
  2001年   9篇
  2000年   10篇
  1999年   5篇
  1998年   6篇
  1997年   10篇
  1996年   4篇
  1994年   3篇
  1992年   4篇
  1990年   4篇
  1989年   3篇
  1988年   4篇
  1987年   3篇
  1986年   3篇
  1985年   6篇
  1981年   1篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1972年   2篇
  1970年   1篇
  1937年   2篇
  1936年   3篇
  1934年   1篇
  1933年   1篇
排序方式: 共有1143条查询结果,搜索用时 31 毫秒
41.
42.
Although spatial smoothing of fMRI data can serve multiple purposes, increasing the sensitivity of activation detection is probably its greatest benefit. However, this increased detection power comes with a loss of specificity when non-adaptive smoothing (i.e. the standard in most software packages) is used. Simulation studies and analysis of experimental data was performed using the R packages neuRosim and fmri. In these studies, we systematically investigated the effect of spatial smoothing on the power and number of false positives in two particular cases that are often encountered in fMRI research: (1) Single condition activation detection for regions that differ in size, and (2) multiple condition activation detection for neighbouring regions. Our results demonstrate that adaptive smoothing is superior in both cases because less false positives are introduced by the spatial smoothing process compared to standard Gaussian smoothing or FDR inference of unsmoothed data.  相似文献   
43.
Patients with Shwachman–Diamond syndrome (SDS) do not only experience well‐described physical features like skeletal abnormalities and hematological dysfunctions, but recent studies also suggested attention and working memory deficits in SDS. Indeed, a recent structural magnetic resonance imaging (MRI) study demonstrated smaller brain regions in SDS. Regarding attention and working memory, however, an important role for the neurotransmitter dopamine is well established. Therefore, in this study we assessed in vivo dopamine transporters (DATs; a specific marker of dopaminergic cells expressed in nerve terminals) and performed structural MRI in SDS. In 6 and 5 young SDS patients, respectively, we were able to acquire DAT single photon emission computed tomography (SPECT) and MRI examinations, and the data were compared to age‐matched control data. Striatal DAT binding was significantly increased in SDS patients as compared to controls. In addition, we observed significantly smaller volumes particularly posteriorly and caudally located in the brain: the corpus callosum, brainstem, and cerebellum. Also the thalamus was smaller in SDS patients than in controls. In conclusion, our data replicate earlier findings on smaller brain regions in SDS. In addition, our novel molecular imaging data suggest that SDS patients may have a dysregulated dopaminergic system. These findings may be of relevance to increase our understanding of behavioral and cognitive deficits in SDS. © 2012 Wiley Periodicals, Inc.  相似文献   
44.
Patient matched instrumentation is a new operative tool in the field of total knee arthroplasty. Custom made cutting blocks are designed to perform distal femoral and tibial bone cuts according to a pre-operative planning. This study evaluates the Visionaire system of Smith & Nephew. Thirty-one patients, operated with the Visionaire technique, were compared to an equal control group for different clinical and radiographic outcome parameters. Between both groups, no statistical significant difference could be found in post-operative pain, satisfaction, functional outcome, hospital stay, blood loss, radiographic alignment and precision of bone cuts. Only tibial plateau backslope can be created with more precision in the Visionaire group. But there was a statistical significant difference for residual flexion deformity after a mean follow-up time of 200 days.  相似文献   
45.

Objective

To assess undiagnosed and comorbid disorders in patients referred to a tertiary care center with a presumed diagnosis of chronic fatigue syndrome (CFS).

Methods

Patients referred for chronic unexplained fatigue entered an integrated diagnostic pathway, including internal medicine assessment, psychodiagnostic screening, physiotherapeutic assessment and polysomnography + multiple sleep latency testing. Final diagnosis resulted from a multidisciplinary team discussion. Fukuda criteria were used for the diagnosis of CFS, DSM-IV-TR criteria for psychiatric disorders, ICSD-2 criteria for sleep disorders.

Results

Out of 377 patients referred, 279 (74.0%) were included in the study [84.9% female; mean age 38.8 years (SD 10.3)].A diagnosis of unequivocal CFS was made in 23.3%. In 21.1%, CFS was associated with a sleep disorder and/or psychiatric disorder, not invalidating the diagnosis of CFS. A predominant sleep disorder was found in 9.7%, 19.0% had a psychiatric disorder and 20.8% a combination of both. Only 2.2% was diagnosed with a classical internal disease.In the total sample, a sleep disorder was found in 49.8%, especially obstructive sleep apnea syndrome, followed by psychophysiologic insomnia and periodic limb movement disorder. A psychiatric disorder was diagnosed in 45.2%; mostly mood and anxiety disorder.

Conclusions

A multidisciplinary approach to presumed CFS yields unequivocal CFS in only a minority of patients, and reveals a broad spectrum of exclusionary or comorbid conditions within the domains of sleep medicine and psychiatry. These findings favor a systematic diagnostic approach to CFS, suitable to identify a wide range of diagnostic categories that may be subject to dedicated care.  相似文献   
46.
BACKGROUND: Asthma and excessive body weight frequently coexist, whereas the exact relationship between the 2 diseases is unknown. OBJECTIVE: To study whether asthma combined with excessive body weight has a greater effect on quality of life in children than the separate effects of asthma or excessive body weight alone. METHODS: In a cross-sectional design, 1758 school children (age 7-10 years) participated: 4 study groups were composed of children with asthma and with/without excessive body weight, and healthy controls with/without excessive body weight. Diagnosis of asthma was defined by either a doctor's diagnosis or by core questions of the International Study of Asthma and Allergies in Childhood questionnaire in combination with either reversible airway obstruction or bronchial hyperresponsiveness. Excessive body weight was defined by using international cutoff points for body mass index. Quality of life was evaluated by the Pediatric Asthma Quality of Life Questionnaire. RESULTS: For all domains of quality of life, children with both asthma and excessive body weight had lower scores than children with either asthma alone or excessive body weight alone. Compared with healthy controls, the score was 25% lower in children with asthma and excessive body weight, 14% lower in children with asthma and normal weight, and only 1% lower in overweight controls. CONCLUSION: Excessive body weight is associated with an additional decrease in quality of life in children with asthma. CLINICAL IMPLICATIONS: Clinicians should be aware of the interaction between asthma and excessive body weight and the effect on quality of life and should give extra attention to children with both conditions.  相似文献   
47.
Stereo vision enhances the learning of a catching skill   总被引:1,自引:0,他引:1  
The aim of this study was to investigate the contribution of stereo vision to the acquisition of a natural interception task. Poor catchers with good (N = 8; Stereo+) and weak (N = 6; Stereo-) stereo vision participated in an intensive training program spread over 2 weeks, during which they caught over 1,400 tennis balls in a pre-post-retention design. While the Stereo+ group improved from a catching percentage of 18% to 59%, catchers in the Stereo- group did not significantly improve (from 10 to 31%), this progress being indifferent from a control group (N = 9) that did not practice at all. These results indicate that the development and use of of compensatory cues for depth perception in people with weak stereopsis is insufficient to successfully deal with interceptions under high temporal constraints, and that this disadvantage cannot be fully attenuated by specific and intensive training.  相似文献   
48.
Aims: Alcohol advertising, in the form of product placement, has been shown to influence the viewer’s alcohol consumption. However, it is not just the portrayal itself that affects behavioural outcomes; the particular message that is conveyed in an alcohol portrayal may actually influence consumer behaviour in a manner known as “framing”. Therefore, the prevalence and framing of alcohol portrayals in movies was investigated by focussing on product placement strategies, several portrayal characteristics and compliance with relevant guidelines/laws. Furthermore, a comparison is made between movies sponsored by an alcohol brand and non-sponsored movies.

Methods: Sixteen Dutch movies (of which 50% were sponsored) underwent content analysis using a four-category, 21-item coding scheme. Alcohol was present in every movie and a total of 937 alcohol portrayals were analysed.

Findings: The results show that the alcohol portrayals were predominantly positive. In the sponsored movies, more liquor was consumed and alcohol portrayals had a lower plot connection.

Conclusions: In general, the differences between alcohol portrayals in movies sponsored by an alcohol brand compared with non-sponsored movies were rather small. However, the portrayals sometimes offend the legislation regarding regular alcohol commercials, and given the effects of alcohol portrayals on young viewers, this needs attention.  相似文献   

49.
Nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to have weak but beneficial effects on bone health, including fracture risk, but many epidemiological studies are likely confounded. We explored the relationship between NSAIDs and fracture risk in a post hoc analysis of a well-documented, randomized, placebo-controlled study of the bisphosphonate, clodronate, in which treatment reduced osteoporotic fracture risk by 23%. Concurrent medication use at baseline was used to identify those prescribed oral NSAIDs. Only verified, incident fractures were included in the analysis. A total of 1082 (20.8%) women reported use of NSAIDs at baseline. They were slightly, but significantly, younger (mean 79 versus 80 years, p = 0.004), heavier (mean 66.7 versus 64.7 kg, p < 0.001) than nonusers, with slightly higher femoral neck bone mineral density (FN-BMD, 0.66 versus 0.64 g/cm2, p < 0.001). In an adjusted model, NSAID use was associated with a significant increase in osteoporotic fracture risk over the 3-year study period (hazard ratio [HR] 1.27; 95% confidence interval [CI], 1.01–1.62; p = 0.039). However, this increase in risk was not statistically significant in the placebo group (HR 1.11; 95% CI, 0.81–1.52). In women receiving clodronate, the effect of the bisphosphonate to reduce osteoporotic fracture risk was not observed in those receiving NSAIDs (HR 0.95; 95% CI, 0.65–1.41; p = 0.81) in contrast to those not using NSAIDs (HR 0.71; 95% CI, 0.58–0.89; p = 0.002). In a subset with hip BMD repeated at 3 years, BMD loss during clodronate therapy was greater in those women receiving NSAIDs than in nonusers (eg, total hip −2.75% versus −1.27%, p = 0.078; femoral neck −3.06% versus −1.12%, p = 0.028), and was not significantly different from that observed in women receiving placebo. The efficacy of the bisphosphonate, clodronate, to reduce fracture risk was largely negated in those receiving NSAIDs. Although the mechanism is unclear, this clinically significant observation requires exploration in studies of commonly used bisphosphonates. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).  相似文献   
50.
Congenital left ventricular diverticula are rare cardiac malformations that usually remain asymptomatic. However, life-threatening complications as ventricular arrhythmias, systemic embolism, spontaneous rupture and development of valvular regurgitation, are described. Diagnosis is based on excluding coronary artery disease, traumatic or inflammatory causes, and other underlying cardiomyopathies. Treatment is directed towards the potential complications, yielding mainly therapy of ventricular arrhythmia. Surgical resection is required for larger-sized congenital aneurysms with adverse hemodynamic effects. We present two cases of a left ventricular diverticulum causing cardiac arrhythmia which led to further surgical treatment.  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