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   840篇
  免费   37篇
  国内免费   3篇
耳鼻咽喉   6篇
儿科学   41篇
妇产科学   41篇
基础医学   133篇
口腔科学   28篇
临床医学   81篇
内科学   158篇
皮肤病学   18篇
神经病学   42篇
特种医学   21篇
外科学   58篇
综合类   11篇
预防医学   48篇
眼科学   38篇
药学   103篇
中国医学   7篇
肿瘤学   46篇
  2024年   1篇
  2023年   9篇
  2022年   28篇
  2021年   55篇
  2020年   22篇
  2019年   36篇
  2018年   41篇
  2017年   33篇
  2016年   38篇
  2015年   35篇
  2014年   48篇
  2013年   67篇
  2012年   86篇
  2011年   86篇
  2010年   30篇
  2009年   37篇
  2008年   49篇
  2007年   37篇
  2006年   16篇
  2005年   35篇
  2004年   27篇
  2003年   14篇
  2002年   20篇
  2001年   2篇
  1999年   3篇
  1998年   3篇
  1997年   2篇
  1996年   4篇
  1995年   3篇
  1994年   3篇
  1992年   2篇
  1991年   4篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
排序方式: 共有880条查询结果,搜索用时 15 毫秒
51.
52.
53.
Objective To estimate the heavy metal content in soil and selected medicinal plants procured from environmentally different sites of the same city. Methods Soil and plant samples of Abutilon indicum, Calotropis procera, Euphorbia hirta, Peristrophe bycaliculata, and Tinospora cordifolia were collected from 3 environmentally different sites of the city: heavy traffic area (HTA), industrial area (IA), and residential area (RA). Pb by inductively coupled plasma emission spectrometry and compared Cd, Cr, and Ni were estimated in soil and plant samples Results The level of heavy metal was higher in soil than in plant parts studied. Accumulation of heavy metals varied from plant to plant. Pb was the highest in Calotropis procera root from HTA site and the lowest in Peristrophe bycaliculata whole plant from IA site. It was also lower in residential area than in heavy traffic area. Conclusion The level of heavy metal content differed in the same medicinal plant collected from environmentally different sites of the same city. Thus, it reiterates our belief that every medicinal plant sample should be tested for contaminant load before processing it further for medication.  相似文献   
54.
Kinematic properties of trunk extension are considered sensitive differentiators of movement between asymptomatic and low back pain subjects. The aim of this study was to quantify the continuous interaction of the hip and lumbar spine kinematics and temporal characteristics as a function of direction during the task of trunk bending backwards and returning to the upright position in healthy young subjects. The sagittal hip and lumbar spine kinematics during the extension task were examined in 18 healthy male subjects. Five trials of trunk extension were recorded for each subject and paired t-tests were then used to determine significant differences (P < 0.05) between the mean lumbar and the hip time-normalized kinematic and temporal variables. The data from the full cycle of trunk extension was analyzed with respect to movement initiation, time to reach peak velocity and peak angular displacement during the full cycle of trunk extension. Three distinct phases of movements were identified based on the continuous movement trajectories of velocity and angular displacement in the lumbar spine and hip; that of extension, return and, a terminal overcorrection phase. There were significant differences identified in the respective mean peak angular velocities of the lumbar spine (21.7 +/- 8.6, 37.0 +/- 14.7, 8.3 +/- 5.0 deg/s) when compared with those of hip (14.6 +/- 6.1, 21.7 +/- 8.5, 5.4 +/- 3.5 deg/s) in each of these three phases. The lumbar spine initiated the movement of trunk extension when bending backwards and returning to the upright position significantly early than that of the hip. These results highlight that in normal healthy adults there is the tendency for the lumbar spine to dominate over the hip during the task of backward trunk bending in terms of the amount and velocity of movement. At the end of extension the kinematics of the lumbar spine and hip kinematic are characterized by a terminal overcorrection phase marking the completion of the movement.  相似文献   
55.
The lungs and hearts of 15 swine were surgically harvested intact and studied in the fresh state. The lymphatics of the lung and mediastinum were cannulated and contrast medium was introduced by retrograde injection to identify the visceral pleural lymphatics and deep lymphatics of the lung. Radiographic x-ray, CT, MR, and color photographic images were obtained. Collateralization, extravasation (bronchorrhea), perivascular stasis, and circumvention were demonstrated. Lymphatic communication with the contralateral lung, thoracic duct, heart, and the diaphragm was demonstrated. The findings correlate with the lymphangiographic display of lymphedema of the extremities, obstruction to lymph flow secondary to congenital abnormalities, trauma, tumor, and infections. Our results support the view that stents and/or large bore needles may be introduced into the superficial lymphatics of the lung. The lymphatics of the lung may be anastomosed post lung transplantation and thus possibly reduce passive congestion that occurs in the early postoperative period. The authors postulate that tumor cells and infectious agents may be spread from one lung to the other by the anatomical pathways demonstrated.  相似文献   
56.
The development of agents that affect two or more relevant targets has drawn considerable attention in treatment of AD. Diallyl disulfide (DADS), an active principle of garlic, has been reported to prevent APP processing by amyloidogenic pathway. Recently, we have reported a new series of DADS derivatives and our findings revealed that compound 7k and 7l could provide good templates for developing new multifunctional agents for AD treatment. Thus, the present study was constructed to investigate the neuroprotective effect of DADS analogues (7k and 7l) against Aβ-induced neurotoxicity in SH-SY5Y human neuroblastoma cells and in ameliorating the cognition deficit induced by scopolamine in rat model. The results indicated that compound 7k and 7l significantly inhibited Aβ1–42-induced neuronal cell death by inhibiting ROS generation. Moreover, they prevented apoptosis, in response to ROS, by restoring normal Bax/Bcl-2 ratio. Furthermore, it was observed that scopolamine-induced memory impairment was coupled by alterations in neurotransmitters, acetylcholinesterase activity and oxidative stress markers. Histological analysis revealed severe damaging effects of scopolamine on the structure of cerebral cortex and hippocampus. Administration of compounds 7k and 7l at 5 mg/kg significantly reversed scopolamine-induced behavioural, biochemical, neurochemical and histological changes in a manner comparable to standard donepezil. Together the present findings and previous studies indicate that compounds 7k and 7l have neuroprotective and cognition-enhancing effects, which makes them a promising multi-target candidate for addressing the complex nature of AD.  相似文献   
57.
Nephropathic cystinosis is a rare, inherited metabolic disease caused by functional defects of cystinosin associated with mutations in the CTNS gene. The mechanisms underlying the phenotypic alterations associated with this disease are not well known. In this study, gene expression profiles in peripheral blood of nephropathic cystinosis patients (N = 7) were compared with controls (N = 7) using microarray technology. In unsupervised hierarchical clustering analysis, cystinosis samples co-clustered, and 1,604 genes were significantly differentially expressed between both groups. Gene ontology analysis revealed that differentially expressed genes in cystinosis were enriched in cell organelles such as mitochondria, lysosomes, and endoplasmic reticulum (p ≤ 0.030). The majority of the differentially regulated genes were involved in oxidative phosphorylation, apoptosis, mitochondrial dysfunction, endoplasmic reticulum stress, antigen processing and presentation, B-cell-receptor signaling, and oxidative stress (p ≤ 0.003). Validation of selected genes involved in apoptosis and oxidative phosphorylation was performed by quantitative real-time polymerase chain reaction (PCR). Electron microscopy and confocal imaging of cystinotic renal proximal tubular epithelial cells further confirmed anomalies in the cellular organelles and pathways identified by microarray analysis. Further analysis of these genes and pathways may offer critical insights into the clinical spectrum of cystinosis patients and ultimately lead to novel links for targeted therapy.  相似文献   
58.
The objective of this study was to develop and characterize a novel dithranol-containing phospholipid microemulsion systems for enhanced skin permeation and retention. Based on the solubility of dithranol, the selected oils were isopropyl myristate (IPM) and tocopherol acetate (TA), and the surfactants were Tween 80 (T80) and Tween 20 (T20). The ratios of cosurfactants comprising of phospholipids and ethanol (1?:?10) and surfactant to co-surfactant (1?:?1 and 2.75?:?1) were fixed for the phase diagram construction. Selected microemulsions were evaluated for globule size, zeta potential, viscosity, refractive index, per cent transmittance, stability (freeze thaw and centrifugation), ex vivo skin permeation and retention. The microemulsion systems composed of IPM and T80 with mean particle diameter of 72.8?nm showed maximum skin permeation (82.23%), skin permeation flux (0.281?mg/cm2/h) along with skin retention (8.31%) vis-à-vis systems containing TA and T20. The results suggest that the developed novel lecithinized microemulsion systems have a promising potential for the improved topical delivery of dithranol.  相似文献   
59.
60.
An atypical presentation of post-kala-azar dermal leishmaniasis is reported to highlight the importance of suspecting dermatosis in patients from areas endemic for kala-azar.  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