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   543篇
  免费   49篇
  国内免费   5篇
耳鼻咽喉   4篇
儿科学   21篇
妇产科学   23篇
基础医学   69篇
口腔科学   11篇
临床医学   58篇
内科学   159篇
皮肤病学   15篇
神经病学   22篇
特种医学   26篇
外科学   39篇
综合类   10篇
预防医学   25篇
眼科学   29篇
药学   53篇
中国医学   1篇
肿瘤学   32篇
  2024年   2篇
  2023年   12篇
  2022年   40篇
  2021年   58篇
  2020年   38篇
  2019年   40篇
  2018年   44篇
  2017年   39篇
  2016年   31篇
  2015年   17篇
  2014年   33篇
  2013年   42篇
  2012年   47篇
  2011年   39篇
  2010年   18篇
  2009年   18篇
  2008年   14篇
  2007年   16篇
  2006年   14篇
  2005年   7篇
  2004年   6篇
  2003年   12篇
  2002年   5篇
  2000年   2篇
  1998年   2篇
  1995年   1篇
排序方式: 共有597条查询结果,搜索用时 15 毫秒
11.

Much concern was directed towards the crucial role of recombinant tissue plasminogen activator (rt-PA) in improving neuroplasticity in patients with acute ischemic stroke. The aim of the work to investigate the effect of treating patients with acute ischemic stroke with rt-PA, on the level of brain derived neurotrophic factor (BDNF) as a marker of neuroplasticity. This study was conducted on 47 patients presenting with acute ischemic stroke (during the first 4.5 h from stroke onset); 26 patients of them eligible for receiving rt-PA (patient group) and 21 patients having contraindications for treatment with rt-PA (control group). Neurological, radiological and laboratory assessment (including BDNF serum level) were done for both groups at stroke onset (before receiving rt-PA) and at day 7. There was a statistically significant increase in BDNF serum level from day 1 to day 7 in rt-PA treated patients in comparison to control group (P-value? 0.001). Serum level of BDNF is significantly higher at the onset of stroke in female patients and non-smokers than males or smokers (P-value?=?0.011, 0.01 respectively). There was no effect of either age, body mass index, hypertension, diabetes, drug abuse, past or family history of stroke, valvular heart diseases, atrial fibrillation, cardiomyopathy, ejection fraction, carotid atherosclerotic changes, lipid profile or uric acid, on BDNF serum level measured at the onset of stroke. Treatment of patients with acute ischemic stroke with rt-PA causes significant improvement in neuroplasticity through increasing BDNF serum level.

  相似文献   
12.
Methotrexate (MTX) is a widely used chemotherapeutic agent; nevertheless, the nephrotoxicity associated with its use has limited its clinical use. Rebamipide (REB) is a gastro-protective agent with diverse promising biological activities. Here, we investigated the renoprotective effects of REB against MTX-induced nephrotoxicity in rats. Male Wistar rats were allocated into four groups: the normal control group, the REB group (100 mg kg−1 day−1, PO, for 12 days), the MTX group (which received a single injection of 20 mg/kg, ip), and the REB + MTX group (which received 100 mg kg−1 day−1 REB for 7 days before and 5 days after being injected with 20 mg/kg MTX). Interestingly, MTX triggered kidney injury, characterized by renal dysfunction along with histopathological alterations. Moreover, increased reactive oxygen species level and inflammatory response were detected in the kidney of MTX-treated rats. However, REB prevented MTX-induced oxidative kidney injury and boosted an antioxidant balance. Mechanistically, REB markedly activated the NRF-2 protein and upregulated the expression of both SIRT-1 and FOXO-3 genes. Additionally, REB administration strongly inhibited the inflammatory response by downregulating both NF-κB-p65 and TLR-4. Finally, the coadministration of REB and MTX activated the mTOR/PI3K/AKT signaling pathway. Simultaneously, REB treatment attenuated the reduction in glomerular size, the widening of the capsular spaces, and the tubular cell damage due to MTX administration. Taken together, these results indicate the potential of REB as adjuvant therapy to prevent nephrotoxicity in patients receiving MTX treatment.  相似文献   
13.
Natural use of language involves at least two individuals. Some studies have focused on the interaction between senders in communicative situations and how the knowledge about the speaker can bias language comprehension. However, the mere effect of a face as a social context on language processing remains unknown. In the present study, we used event-related potentials to investigate the semantic and morphosyntactic processing of speech in the presence of a photographic portrait of the speaker. In Experiment 1, we show that the N400, a component related to semantic comprehension, increased its amplitude when processed within this minimal social context compared to a scrambled face control condition. Hence, the semantic neural processing of speech is sensitive to the concomitant perception of a picture of the speaker’s face, even if irrelevant to the content of the sentences. Moreover, a late posterior negativity effect was found to the presentation of the speaker’s face compared to control stimuli. In contrast, in Experiment 2, we found that morphosyntactic processing, as reflected in left anterior negativity and P600 effects, is not notably affected by the presence of the speaker’s portrait. Overall, the present findings suggest that the mere presence of the speaker’s image seems to trigger a minimal communicative context, increasing processing resources for language comprehension at the semantic level.  相似文献   
14.
ObjectiveThis study aimed to assess the effect of different storage media on the hardness and monomer elution of CAD/CAM composite blocks.MethodsFive resin-composite blocks (RCB), one polymer-infiltrated ceramic network (PICN) block (Enamic (EN)), one ceramic-filled poly ether ether ketone (PEEK) block (Dentokeep (DK)), and one feldspathic ceramic block. Microhardness was measured using a Vickers indenter tester (FM-700, Future Tech Corp., Japan). In addition 4 conventional resin-composites were investigated for monomer elution using high performance liquid chromatography (HPLC) after storage in different media for 3 months. The data were analysed by three-way ANOVA, two-way ANOVA, one-way ANOVA, Tukey’s post hoc test and the independent t-test (α = 0.05 for all tests).ResultsThe specimens stored in the water had a hardness reduction ranging from 0.9% to 24.4%. In artificial saliva, the specimens had a hardness reduction ranging from 2.8% to 23.2%. The hardness reduction percentage in 75% Ethanol/Water (E/W) ranged between 3.8% and 35.3%. All materials, except GR (resin-composite block) and DK (Polyetheretherketone (PEEK)), showed a variable extent of monomer elution into 75% E/W with significantly higher amounts eluted from conventional composites. GRA and GND (conventional resin-composites) eluted TEGDMA in artificial saliva and GRA eluted TEGDMA in water.SignificanceThe hardness of CAD/CAM composite blocks was affected by different storage media, and they were not as stable as ceramic, with PICN exhibited superior hardness stability to all of the resin-composite blocks in all the storage media and was comparable to ceramic block. The hardness reduction percentage of the CAD/CAM composite blocks was influenced by the filler loading and resin-matrix composition.Minimal or no monomer elution from CAD/CAM blocks was detected.  相似文献   
15.
Aging is an unavoidable fate that afflicts all life, during this process in mammals reactive oxygen species (ROS) are generated which stimulate tyrosinase, elastase and collagenase activities that actively participate in skin aging. Therefore, the maintenance of antioxidant homeostasis is an important anti-aging strategy for skin. Nature has excellent anti-aging remedies that act externally as well as internally to delay the visual signs of aging. In view of this fact, the present study investigates the in vitro anti-aging activity of five medicinal plants belonging to phenolic rich families namely Rosmarinus officinalis, Lavandula officinalis, Matricaria chamomilla, Camellia sinensis and Pelargonium graveolens. The selected plants are those most frequently used in the preparation of ethnomedicinal recipes for the prevention or treatment of aging. The inhibitory effects of the ethanolic and aqueous extracts of the five selected plants on the activity of tyrosinase, elastase, and collagenase enzymes were investigated. Furthermore, the chemical composition of the plants and the antioxidant capacity of their extracts were assessed. The results showed that R. officinalis had the highest total phenolics content which was correlated with its potent antioxidant and anti-aging activities. To pinpoint the active metabolites in the tested extracts, we evaluated the metabolite variations using ultra-performance liquid chromatography coupled with high resolution electrospray ionization-tandem mass spectrometry (UPLC-HR-ESI-MS/MS). Multivariate data analysis (MVDA) revealed that R. officinalis significantly accumulated metabolites from the aromatic diterpenoid, flavonoid and phenolic acid classes. These results indicate that rosemary can be used for further development of topical preparations with anti-aging properties.

Aging is an unavoidable fate that afflicts all life, during this process in mammals, reactive oxygen species (ROS) are generated which stimulate tyrosinase, elastase and collagenase activities that actively participate in skin aging.  相似文献   
16.
17.
The low dose of radiation (LDR) has received growing attention for its beneficial neuroprotective effect. This study was designed to investigate the enhancing effect of LDR on the antidepressant potential of resveratrol against diazepam‐induced depression in mice. Female mice divided into five groups; control, diazepam (2 mg/kg), LDR (0.5Gy) + diazepam, resveratrol (20 mg/kg) + diazepam, LDR + resveratrol+diazepam. Mice received diazepam showed depressive symptoms as evidenced by decreased locomotor activity in the open field and increased immobility time in the forced swimming and tail suspension tests integrated with a marked decline in biogenic amines (serotonin, norepinephrine, and dopamine) in brain tissues. These effects were ameliorated by LDR or resveratrol administration demonstrating an antidepressant activity. Interestingly, LDR triggered the antidepressant effect of resveratrol as it restored the changes in behavioral tests, neurotransmitters, and neuro‐histoarchitecture. In conclusion, these findings suggested that LDR could be considered as a novel adjuvant that augmented the resveratrol antidepressant effect and might serve as a potential therapeutic approach for depression.  相似文献   
18.
Colon cancer is a complex disease that involves numerous genetic alterations that change the normal colonic mucosa into invasive adenocarcinoma. In the current study, the protective effects of inulin (prebiotic), Lactobacillus casei (L. casei, probiotic) and their combination (synbiotic) on 1,2-dimethylhydrazine (DMH)-induced colon cancer in male Swiss mice were evaluated. Animals were divided into: Control group, DMH-treated group, DMH plus inulin, DMH plus L. casei and DMH plus inulin plus L. casei-treated groups. Fecal microbiome analysis, biochemical measurements, histopathological examination of the colon tissues, immunostaining and Western blotting analysis of β-catenin, GSK3β and JNK-1 were performed. The prebiotic-, probiotic- and synbiotic-treated groups showed decreased levels of carcinoembryonic antigen and a lower number of aberrant crypt foci compared to the DMH-treated group with the synbiotic group exhibiting a superior effect. Furthermore, all treatments showed a body weight-reducing effect. Administration of inulin, L. casei or their combination increased the expression level of phospho-JNK-1 while they decreased the expression level of β-catenin and phospho-GSK3β. Remarkably, L. casei treatment resulted in enrichment of certain beneficial bacterial genera i.e. Akkermansia and Turicibacter. Therefore, administration of L. casei and inulin as a synbiotic combination protects against colon cancer in mice.

The lactobacillus casei and inulin modulate the expression of JNK-1, GSK3β and β-catenin proteins and enrich the beneficial bacteria to protect from colon cancer in mice.  相似文献   
19.
20.
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