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   460篇
  免费   25篇
  国内免费   5篇
耳鼻咽喉   4篇
儿科学   9篇
妇产科学   19篇
基础医学   86篇
口腔科学   11篇
临床医学   51篇
内科学   68篇
皮肤病学   16篇
神经病学   33篇
特种医学   10篇
外科学   23篇
综合类   5篇
预防医学   56篇
眼科学   14篇
药学   58篇
中国医学   6篇
肿瘤学   21篇
  2023年   14篇
  2022年   19篇
  2021年   38篇
  2020年   37篇
  2019年   26篇
  2018年   35篇
  2017年   22篇
  2016年   23篇
  2015年   30篇
  2014年   16篇
  2013年   37篇
  2012年   38篇
  2011年   36篇
  2010年   21篇
  2009年   12篇
  2008年   16篇
  2007年   15篇
  2006年   13篇
  2005年   5篇
  2004年   5篇
  2003年   4篇
  2002年   3篇
  2001年   5篇
  2000年   5篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1996年   1篇
  1994年   1篇
  1989年   1篇
  1988年   1篇
  1985年   2篇
  1976年   2篇
  1971年   1篇
排序方式: 共有490条查询结果,搜索用时 15 毫秒
1.
2.
3.
Purpose: Injuries are one of the leading causes of death and lead to a high social and financial burden. Injury patterns can vary significantly among different age groups and body regions. This study aimed to evaluate the relationship between mechanism of injury, patient comorbidities and severity of injuries. Methods: The study included trauma patients from July 2016 to June 2018, who were admitted to Sina Hospital, Tehran, Iran. The inclusion criteria were all injured patients who had at least one of the following: hospital length of stay more than 24 h, death in hospital, and transfer from the intensive care unit of another hospital. Data collection was performed using the National Trauma Registry of Iran minimum dataset. Results: The most common injury mechanism was road traffic injuries (49.0%), followed by falls (25.5%). The mean age of those who fell was significantly higher in comparison with other mechanisms (p < 0.001). Severe extremity injuries occurred more often in the fall group than in the vehicle collision group (69.0% vs. 43.5%, p < 0.001). Moreover, cases of severe multiple trauma were higher amongst vehicle collisions than injuries caused by falls (27.8% vs. 12.9%, p = 0.003). Conclusion: Comparing falls with motor vehicle collisions, patients who fell were older and sustained more extremity injuries. Patients injured by motor vehicle collision were more likely to have sustained multiple trauma than those presenting with falls. Recognition of the relationship between mechanisms and consequences of injuries may lead to more effective interventions.  相似文献   
4.
Sexuality and Disability - Sexual problems of hemodialysis patients are one of the most significant factors affecting their quality of life and families. On the other hand, an essential part of the...  相似文献   
5.
An automated sleep staging based on analyzing long-range time correlations in EEG is proposed. These correlations, indicating time-scale invariant property or self-similarity at different time scales, are known to be salient dynamical characteristics of stage succession for a sleeping brain even when the subject suffers a destructive disorder such as Obstructive Sleep Apnea (OSA). The goal is to extract a set of complementary features from cerebral sources mapped onto the scalp electrodes or from a number of denoised EEG channels. For this purpose, source localization/extraction and noise reduction approaches based on Independent Component Analysis were used prior to correlation analysis. Feature extracted segments were then classified in one of the five classes including WAKE, STAGE1, STAGE2, SWS and REM via an ensemble neuro-fuzzy classifier. Some techniques were employed to improve the classifier’s performance including Scaled Conjugate Gradient Method to speed up learning the ANFIS classifiers, a pruning algorithm to eliminate irrelevant fuzzy rules and the 10-fold cross-validation technique to train and test the system more efficiently. The performance of classification for two strategies including (1) feature extraction from effective cerebral sources and (2) feature extraction from selected channels of denoised EEG signals was compared and contrasted in terms of training errors and test accuracies. The first and second strategies achieved 92.23 and 88.74% agreement with human expert respectively which indicates the effectiveness of the staging system based on cerebral sources of activity. Our results further indicate that the misclassification rates were almost below 10%. The proposed automated sleep staging system is reliable due to the fact that it is based on the underlying dynamics of sleep staging which is less likely to be affected by sleep fragmentations occurred repeatedly in OSA.  相似文献   
6.
The present study aimed to investigate the applicability of Universal Thermal Climate Index (UTCI) as an innovative and science-based index in public health researches, in occupational heat stress assessment. All indoor and outdoor workers (200 people) of Brick industries of Shahroud, Iran participated in the research. First, the environmental variables such as air temperature, wet-bulb temperature, globe temperature, air velocity and relative humidity were measured; then UTCI and WBGT (wet-bulb globe temperature) indices were calculated. Simultaneously, physiological parameters including systolic and diastolic blood pressure, oral temperature, skin temperature, tympanic temperature and heart rate of workers were measured. UTCI and WBGT indices were 34.2 ± 2°C, 21.8 ± 1.8°C in the outdoor environments and 38.1 ± 4.4°C, 24.7 ± 3.3°C at the indoor environments, respectively. There were the weak inverse relationships between UTCI and WBGT indices at the outdoor environments and physiological responses such as systolic blood pressure, and diastolic blood pressure. However, there were no similar results for indoor environments. The significant relationships were found between UTCI and WBGT at both indoor and outdoor environments. Both UTCI and WBGT indices are suitable for assessing the occupational heat stress. Although, UTCI index seems more appropriate for heat stress assessment in the environments with low humidity and air velocity.  相似文献   
7.
8.
The radioprotective effect of Achillea millefolium L (ACM) extract was investigated against genotoxicity induced by ionizing radiation (IR) in human lymphocytes. Peripheral blood samples were collected from human volunteers and incubated with the methanolic extract of ACM at different concentrations (10, 50, 100, and 200 μg/mL) for 2 hours. At each dose point, the whole blood was exposed in vitro to 2.5 Gy of X-ray and then the lymphocytes were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis-blocked binucleated cell. Antioxidant capacity of the extract was determined using free radical-scavenging method. The treatment of lymphocytes with the extract showed a significant decrease in the incidence of micronuclei binucleated cells, as compared with similarly irradiated lymphocytes without any extract treatment. The maximum protection and decrease in frequency of micronuclei were observed at 200 μg/mL of ACM extract which completely protected genotoxicity induced by IR in human lymphocytes. Achillea millefolium extract exhibited concentration-dependent radical-scavenging activity on 1,1-diphenyl-2-picryl hydrazyl free radicals. These data suggest that the methanolic extract of ACM may play an important role in the protection of normal tissues against genetic damage induced by IR.  相似文献   
9.
Modification of various properties of graphene oxide (GO) films on SiO2/Si substrate under KrF laser radiation was extensively studied. X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and the electrical resistance measurements were employed to correlate the effects of laser irradiation on structural, chemical and electrical properties of GO films under different laser fluences. Raman spectroscopy shows reduced graphene oxide patterns with increased I2D/IG ratios in irradiated samples. X-ray photoelectron spectroscopy shows a high ratio of carbon to oxygen atoms in the reduced graphene oxide (rGO) films compared to the pristine GO films. X-ray diffraction patterns display a significant drop in the diffraction peak intensity after laser irradiation. Finally, the electrical resistance of irradiated GO films reduced by about four orders of magnitudes compared to the unirradiated GO films. Simultaneously, reduction and patterning of GO films display promising fabrication technique that can be useful for many graphene-based devices.

Modification of various properties of graphene oxide (GO) films on SiO2/Si substrate under KrF laser radiation was extensively studied.  相似文献   
10.
OBJECTIVES: Previous studies showed that antiphospholipid antibodies (aPL) are frequent in the sera of leprosy patients and are most probably directed against body tissue cardiolipins. Some groups have demonstrated differences between the binding specificity of "autoimmune-aPL" and "non-autoimmune-aPL". It is widely accepted that a plasma protein, beta 2-Glycoprotein I (beta 2-GPI), is required for the binding of autoimmune anticardiolipin antibodies (aCL) to cardiolipin. However, some reports suggested heterogeneity of leprosy aCL with respect to their beta 2-Glycoprotein I (beta 2GPI) dependency, although no thromboembolic complications have been reported. This study was designed to assess the specificity of aPL by investigating the prevalence of aCL, anti-phosphatidylserine (aPS), anti-phosphatidylinositol (aPI), anti-beta 2GPI and antiprothrombin (aPT) antibodies, and evaluate their clinical significance in a group of patients with lepromatous leprosy. PATIENTS AND METHODS: 35 lepromatous leprosy patients were selected randomly from an Egyptian leprosarium as a study group. 35 normal household contact controls were selected matching the study group for both sex and age. aCL, aPS, aPI, aPT, anti-beta 2GPI and beta 2-dependent aCL antibodies were investigated by ELISA in all patients and controls. RESULTS: aCL antibodies were more frequent in leprosy patients than in controls [13/35 (37%) vs. 3/35 (9%), respectively, p = 0.02] and significantly correlated with Raynaud's phenomenon, skin nodules, chronic skin ulcers and urticarial skin rash. No association was found with hypopigmentation, hyperpigmentation and saddle nose. None of the patients presented aPS nor aPI. Only 1 subject from the control group presented aPI along with aCL. aPT were present in 2/35 (5.7%) and anti-beta 2GPI in 1/35 (2.9%) leprotic patients. None of the individuals from the control group presented aPT nor anti-beta 2GPI. CONCLUSIONS: An association was found between the presence of aCL and certain dermatological manifestations of leprosy, such as Raynaud's phenomenon, skin nodules, chronic skin ulcers and urticarial skin rash. As in other infectious diseases, there was a lack of beta 2GPI-dependency and an absence of thrombotic complications.  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