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   4042篇
  免费   270篇
  国内免费   17篇
耳鼻咽喉   21篇
儿科学   119篇
妇产科学   93篇
基础医学   760篇
口腔科学   135篇
临床医学   335篇
内科学   713篇
皮肤病学   138篇
神经病学   609篇
特种医学   139篇
外科学   402篇
综合类   23篇
一般理论   2篇
预防医学   223篇
眼科学   67篇
药学   293篇
中国医学   2篇
肿瘤学   255篇
  2024年   2篇
  2023年   38篇
  2022年   53篇
  2021年   96篇
  2020年   81篇
  2019年   112篇
  2018年   99篇
  2017年   72篇
  2016年   110篇
  2015年   129篇
  2014年   165篇
  2013年   166篇
  2012年   307篇
  2011年   331篇
  2010年   192篇
  2009年   189篇
  2008年   315篇
  2007年   294篇
  2006年   282篇
  2005年   246篇
  2004年   282篇
  2003年   239篇
  2002年   211篇
  2001年   25篇
  2000年   27篇
  1999年   37篇
  1998年   41篇
  1997年   34篇
  1996年   26篇
  1995年   23篇
  1994年   28篇
  1993年   20篇
  1992年   12篇
  1991年   10篇
  1990年   4篇
  1986年   6篇
  1985年   3篇
  1984年   2篇
  1982年   2篇
  1977年   1篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1960年   1篇
  1947年   1篇
  1946年   1篇
排序方式: 共有4329条查询结果,搜索用时 15 毫秒
81.
Introduction: People with dementia may be unable to verbally express pain and suffer from untreated pain. Use of analgesics in people with dementia has increased during the last decade, in particular opioid analgesics with high potential for adverse effects.

Areas covered: This article presents a systematic review of the current evidence for safety and tolerability of analgesic drugs from randomized controlled trials in people with dementia. Relevant trials were identified by a literature search in the EMBASE, MEDLINE, and Cochrane databases from inception to November 2018. The search included the main terms ‘dementia’ and ‘analgesic’ or their subterms, and was filtered to limit results to clinical trials.

Expert opinion: Although pain treatment is increasingly recognized as an important clinical issue in people with advanced dementia, there is currently a lack of evidence to support safety evaluations of commonly used analgesics in this group. To inform treatment decisions and enable care providers to appropriately monitor patients at risk of adverse effects, it is necessary to conduct well-designed clinical trials to investigate the relative efficacy and safety of analgesics in people with dementia, with particular emphasis on harmful effects of long-term opioid use as well as short-term use of nonsteroidal anti-inflammatory drugs.  相似文献   

82.
A 100 μg/L or higher concentration of 11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannabinol (THC‐COOH) in blood serum is generally assumed to be associated with regular and/or heavy use of cannabis. At present, determination of the extent of cannabis use by means of the concentration of THC‐COOH in hair has not been assessed. Therefore, we aimed at establishing a threshold for THC‐COOH concentrations in hair to prove frequent consumption by comparing THC‐COOH concentrations in 129 corresponding serum and hair samples, respectively. The concentration of THC‐COOH in the serum was analyzed by gas chromatography–mass spectrometry and in the hair by liquid chromatography–tandem mass spectrometry. Data were statistically evaluated using receiver operating characteristic curves and contingency tables. Our results suggest that a THC‐COOH concentration of ≥4.2 pg/mg in hair was always accompanied by a THC‐COOH concentration of at least 100 μg/L in blood serum. Should this be confirmed by further studies of a larger study population, a hair concentration of 4.2 pg/mg THC‐COOH can be set as a threshold to predict regular and/or heavy consumption of cannabis even if no corresponding blood sample is available for analysis.  相似文献   
83.
Purpose: To describe a novel magnetic resonance imaging (MRI) postprocessing technique for the detection of periventricular nodular heterotopia (PNH) and to evaluate its diagnostic value. The method is a further development of voxel‐based morphometric analysis with focus on a region of interest around the lateral ventricles to increase the sensitivity and specificity for automated detection of abnormally located gray matter in this area. Methods: T1‐weighted MRI volume data sets were normalized and segmented in statistical parametric mapping (SPM 5 software), and the distribution of gray matter was compared to a normal database. As a new approach, individual masks derived from segmentation of the lateral ventricles were used to restrict the search for ectopic gray matter to the periventricular area. PNH were automatically detected by localizing the maximum deviation from the normal database in this area, provided that the z‐score exceeded a certain threshold. The optimal z‐score threshold for maximum sensitivity and specificity was determined by a receiver operating characteristic (ROC) curve analysis. The method was applied in 40 patients with PNH and 400 controls. Key Findings: PNH were detected in 37 of 40 patients, and false positives were found in 34 of 400 controls, amounting to 92.5% sensitivity and 91.5% specificity. In 17 of the patients in whom PNH could be identified, these lesions had been overlooked in the past, and in 8 patients even in the high‐resolution MRI subsequently used for postprocessing. Significance: The results suggest that automated morphometric MRI analysis with focus on ectopic gray matter in the periventricular areas facilitates the evaluation of MRI data and increases the sensitivity for the detection of PNH.  相似文献   
84.
85.
86.
87.
Background: Dermatitis herpetiformis is a chronic severely pruritic dermatosis. It is a cutaneous manifestation of celiac disease. The aim of our study was to collect clinical, histological and immunopathological data on patients who were treated in the University Departments of Dermatology in Würzburg and Lübeck from 1996 to 2008. Patients and Methods: We retrospectively analyzed 32 patients. Only patients with positive findings on direct immunofluorescence microscopy were included in this study. Results: All patients demonstrated skin lesions in the predilection areas of knees, elbows, gluteal region and scalp. The male to female ratio was 1.5 : 1 and the average age was 43 years. The interval between the first symptoms and diagnosis ranged from 6 weeks to 20 years. Direct immunofluorescence microscopy showed that granular IgA deposits were more often found continuously along the dermal‐epidermal junction rather than focally in the tips of the dermal papillae. Results of small intestinal biopsies were available from 29 patients and confirmed the presence of celiac disease in all cases. None of the patients reported gastrointestinal symptoms. IgA antibodies against tissue transglutaminase and epidermal transglutaminase were found in 88% and 94% of patient sera, respectively. Conclusions: The detection of IgA autoantibodies against epidermal transglut‐aminase is the most sensitive serological test in the diagnosis of dermatitis herpetiformis. Our observations confirm that patients with dermatitis herpetiformis usually do not demonstrate apparent gastrointestinal symptoms.  相似文献   
88.
Many community-based participatory research (CBPR) partnerships address social determinants of health as a central consideration. However, research studies that explicitly address racism are scarce in the CBPR literature, and there is a dearth of available community-generated data to empirically examine how racism influences health disparities at the local level. In this paper, we provide results of a cross-sectional, population-based health survey conducted in the urban areas of Genesee and Saginaw Counties in Michigan to assess how a sustained community intervention to reduce racism and infant mortality influenced knowledge, beliefs, and experiences of racism and to explore how perceived racism is associated with self-rated health and birth outcomes. We used ANOVA and regression models to compare the responses of intervention participants and non-participants as well as African Americans and European Americans (N = 629). We found that intervention participants reported greater acknowledgment of the enduring and differential impact of racism in comparison to the non-intervention participants. Moreover, survey analyses revealed that racism was associated with health in the following ways: (1) experiences of racial discrimination predicted self-rated physical health, mental health, and smoking status; (2) perceived racism against one’s racial group predicted lower self-rated physical health; and (3) emotional responses to racism-related experiences were marginally associated with lower birth-weight births in the study sample. Our study bolsters the published findings on perceived racism and health outcomes and highlights the usefulness of CBPR and community surveys to empirically investigate racism as a social determinant of health.  相似文献   
89.
HIV-1 negative factor (Nef) elevates virus replication and contributes to immune evasion in vivo. As one of its established in vitro activities, Nef interferes with T-lymphocyte chemotaxis by reducing host cell actin dynamics. To explore Nef’s influence on in vivo recirculation of T lymphocytes, we assessed lymph-node homing of Nef-expressing primary murine lymphocytes and found a drastic impairment in homing to peripheral lymph nodes. Intravital imaging and 3D immunofluorescence reconstruction of lymph nodes revealed that Nef potently impaired T-lymphocyte extravasation through high endothelial venules and reduced subsequent parenchymal motility. Ex vivo analyses of transendothelial migration revealed that Nef disrupted T-lymphocyte polarization and interfered with diapedesis and migration in the narrow subendothelial space. Consistently, Nef specifically affected T-lymphocyte motility modes used in dense environments that pose high physical barriers to migration. Mechanistically, inhibition of lymph node homing, subendothelial migration and cell polarization, but not diapedesis, depended on Nef’s ability to inhibit host cell actin remodeling. Nef-mediated interference with in vivo recirculation of T lymphocytes may compromise T-cell help and thus represents an important mechanism for its function as a HIV pathogenicity factor.  相似文献   
90.
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