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   10935篇
  免费   981篇
  国内免费   874篇
耳鼻咽喉   88篇
儿科学   146篇
妇产科学   142篇
基础医学   1310篇
口腔科学   127篇
临床医学   1435篇
内科学   1622篇
皮肤病学   129篇
神经病学   590篇
特种医学   503篇
外国民族医学   10篇
外科学   997篇
综合类   1737篇
现状与发展   4篇
一般理论   1篇
预防医学   762篇
眼科学   466篇
药学   1143篇
  8篇
中国医学   595篇
肿瘤学   975篇
  2024年   30篇
  2023年   153篇
  2022年   428篇
  2021年   548篇
  2020年   388篇
  2019年   366篇
  2018年   402篇
  2017年   335篇
  2016年   336篇
  2015年   479篇
  2014年   585篇
  2013年   527篇
  2012年   818篇
  2011年   924篇
  2010年   611篇
  2009年   437篇
  2008年   632篇
  2007年   538篇
  2006年   532篇
  2005年   555篇
  2004年   348篇
  2003年   305篇
  2002年   258篇
  2001年   224篇
  2000年   289篇
  1999年   276篇
  1998年   189篇
  1997年   154篇
  1996年   171篇
  1995年   122篇
  1994年   115篇
  1993年   71篇
  1992年   74篇
  1991年   70篇
  1990年   79篇
  1989年   59篇
  1988年   58篇
  1987年   57篇
  1986年   45篇
  1985年   36篇
  1984年   21篇
  1983年   21篇
  1982年   13篇
  1981年   15篇
  1980年   14篇
  1979年   10篇
  1977年   11篇
  1976年   14篇
  1974年   6篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
201.
Antiphospholipid antibodies (aPL) have been detected in various liver diseases, particularly cirrhosis. The role of alcoholic consumption per se has been suggested. The aim of our study was to assess the prevalence of aPL in patients with alcoholic liver disease at various states and to correlate the presence of aPL with both liver injury and alcoholic consumption. Three groups were prospectively included. Group A: 74 controls (age- and sex-matched); group B: 46 patients with alcoholic steatosis; group C: 28 patients with alcoholic cirrhosis. For each patient, lupus anticoagulant, anticardiolipin antibodies and anti-beta2-glycoprotein I antibodies were tested. The prevalence of aPL (presence of at least one positive test) was 5% in group A, 20% in group B and 50% in group C (P < 0.04). No correlation appeared between aPL and Child Pugh score in group C. No correlation was found between the presence of aPL and alcohol intake in patients with either steatosis or cirrhosis. Our study confirms that aPL positivity is more frequently encountered in patients with alcoholic liver disease than in controls. Their prevalence increases with the degree of histological damage but not with the level of alcoholic intake.  相似文献   
202.
Atherosclerosis is regarded as the disease of the arterial vasculature. The main characteristics of atherosclerosis are the abnormal accumulation of lipids, increased inflammatory cells, matrix deposits, and proliferation of smooth muscle cells. Diabetes mellitus, obesity, and hyperlipidemia are the most studied risk factors of atherosclerosis. One least studied risk factor is the uric acid (UA), a high UA in circulation is interlinked with many pathological processes. Several epidemiological studies suggest elevated UA levels as an essential biomarker in the forecast of several cardiovascular diseases. Available evidence claims that UA upholds the atherosclerosis process via disturbing lipid metabolism, reducing the nitric oxide synthesis in endothelial cells, promoting the proliferation of vascular smooth muscle cells, and overwhelms inflammation. In endothelial dysfunction and coronary artery lesions, UA is considered as an independent predictor. The updated studies on the involvement of hyperuricemia in atherosclerosis prove that treatment with xanthine oxidase (XO) inhibitors not just benefits the treatment of hyperuricemia but also reduces the burden of atherosclerosis to a greater extent. In this review, we highlight how the hyperuricemia affects vascular integrity, causes atherosclerosis, and the mechanism of action of XO inhibitors on atherosclerosis.  相似文献   
203.
A device for continuous monitoring of central fixation utilizes birefringence, the property of the Henle fibers surrounding the human fovea, to change the polarization state of light. A circular scan of retinal birefringence, where the scanning circle encompasses the fovea, allows identification of true central fixation—an assessment much needed in various applications in ophthalmology, psychology, and psychiatry. The device allows continuous monitoring for central fixation over an extended period of time in the presence of fixation targets and distracting stimuli, which may be helpful in detecting attention deficit hyperactivity disorder, autism spectrum disorders, and other disorders characterized by changes in the subject’s ability to maintain fixation. A proof-of-concept has been obtained in a small study of ADHD patients and normal control subjects.  相似文献   
204.
This meta-analysis evaluated preoperative aspiration culture for diagnosing prosthetic joint infection (PJI) in total hip arthroplasty (THA) and total knee arthroplasty (TKA). The pooled sensitivity and specificity were 0.72 (95% confidence interval, 0.65 to 0.78) and 0.95 (0.93 to 0.97), respectively. Subgroup analyses revealed nonsignificant worse diagnostic performance for THA than for TKA (sensitivity, 0.70 versus 0.78; specificity, 0.94 versus 0.96). Preoperative aspiration culture has moderate to high sensitivity and very high specificity for diagnosing PJI.  相似文献   
205.
Primary open-angle glaucoma (POAG) has been suggested to be a neurodegenerative disease associated with altered cerebral vascular hemodynamics and widespread disruption of neuronal activity within the visual, working memory, attention and executive networks. We hypothesized that disturbed neurovascular coupling in visual and higher order cognitive cortices exists in POAG patients and correlates with glaucoma stage and visual field defects. Through multimodal magnetic resonance imaging, we evaluated the cerebral blood flow (CBF)-functional connectivity strength (FCS) correlations of the whole gray matter and CBF/FCS ratio per voxel for all subjects. Compared with normal controls, POAG patients showed reduced global CBF-FCS coupling and altered CBF/FCS ratios, predominantly in regions in the visual cortex, salience network, default mode network, and dorsal attentional network. The CBF/FCS ratio was negatively correlated with glaucoma stage, and positively correlated with visual field defects in the lingual gyrus in POAG patients. Moreover, early brain changes were detected in early POAG. These findings indicate neurovascular coupling dysfunction might exist in the visual and higher order cognitive cortices in POAG patients and its clinical relevance. The results may contribute to the monitoring of POAG progression and provide insight into the pathophysiology of the neurodegenerative process in POAG.  相似文献   
206.
Acute gastroenteritis caused by human noroviruses (NoVs) has become an important public health problem worldwide. This study was carried out to investigate the rates of NoV infections and the genetic characteristics of NoVs in adult outpatients with acute gastroenteritis in Ji’nan, a large eastern city in China. A total of 480 fecal samples were collected from outpatients at the Shandong University Qilu Hospital between June 2010 and May 2011. Of the collected samples, 42 (42/480, 8.75 %) were positive for NoVs by RT-PCR, and seven different genotypes were identified: GI-1, GI-4, GII-1, GII-3, GII-4, GII-6 and GII-13, of which GII-4 was the most prevalent (29/42, 69.0 %). Phylogenetic and Simplot analyses showed that three recombinant strains were detected: two GII-4 polymerase/GII-3 capsid recombinants and one GII-6 polymerase/GII-4 capsid recombinant. This study indicated that NoV was a common causative agent of sporadic acute gastroenteritis in adults in Ji’nan, China, and that NoV GII-4 was the predominant strain during this period. Three recombinant strains were identified in which GII-6 polymerase/GII-4 capsid was detected for the first time in China.  相似文献   
207.
Coronavirus disease 2019 (COVID-19) is an infectious disease that emerged at the end of 2019. On 30 January 2020, the World Health Organization (WHO) classified it as a pandemic. To examine the psychological effects on dental care providers in China in the midst of the COVID-19 outbreak and factors closely associated with those effects, we conducted a cross-sectional study online with 4 widely used self-administered questionnaires: the Patient Health Questionnaire-9, the General Anxiety Disorder-7, the Perceived Stress Scale-10, and the Acute Stress Disorder Scale. Univariate and multivariate analyses were performed to evaluate the variables that potentially affected the mental health of emergency dental care providers. As a result, 969 out of 1035 questionnaires were included in the analysis, with 642 respondents reporting more than 1 symptom (66.3%). The symptom of perceived stress was reported by the largest proportion of the respondents (66.2%, n = 641), and anxiety the least (7.1%, n = 69). After adjustment for confounders, it was found that dental practitioners with preexisting physical health conditions were at higher risk of depression (odds ratio [OR], 1.972; 95% CI, 1.128-3.448; P = .017), and perceived stress (odds ratio, 2.397 95% CI, 1.283-4.478; P = .006). Additionally, feelings of fear, helplessness, or terror resulting from the possibility of contracting COVID-19 were significantly associated with the prevalence of all the 4 psychological symptoms observed (P < .05). In the present study, we found that dental care providers suffered psychological depression, stress, anxiety, and posttraumatic stress disorder (PTSD) during COVID-19, which indicates the importance of psychological support at times of major epidemic outbreaks.Chinese Clinical Trial Registry number: ChiCTR2000031538.  相似文献   
208.
Although bilateral megaureters are not an infrequent occurrence in the urinary tract, bilateral megaureters associated with bilateral renal pelvis dilatation and a giant urinary bladder appear to be rare. In this paper, a cadaver case of an adult Japanese male with bilateral megaureters is described. In addition to describing and illustrating this case, the anatomy and etiology of these anomalous structures is discussed with a brief review of the literature.  相似文献   
209.
210.
We propose an effective and practical decoding method of different mental states for potential applications for the design of brain-computer interfaces, prediction of cognitive behaviour, and investigation of cognitive mechanism. Functional near infrared spectroscopy (fNIRS) signals that interrogated the prefrontal and parietal cortices and were evaluated by generalized linear model were recorded when nineteen healthy adults performed the operation span (OSPAN) task. The oxygenated hemoglobin changes during OSPAN, response, and rest periods were classified with a support vector machine (SVM). The relevance vector regression algorithm was utilized for prediction of cognitive performance based on multidomain features of fNIRS signals from the OSPAN task. We acquired decent classification accuracies for OSPAN vs. response (above 91.2%) and for OSPAN vs. rest (above 94.7%). Eight of the ten cognitive testing scores could be predicted from the combination of OSPAN and response features, which indicated the brain hemodynamic responses contain meaningful information suitable for predicting cognitive performance.  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