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   2117篇
  免费   184篇
  国内免费   220篇
儿科学   23篇
妇产科学   30篇
基础医学   186篇
临床医学   81篇
内科学   140篇
皮肤病学   1篇
神经病学   1065篇
特种医学   11篇
外科学   53篇
综合类   142篇
现状与发展   1篇
预防医学   46篇
眼科学   172篇
药学   434篇
  1篇
中国医学   125篇
肿瘤学   10篇
  2024年   8篇
  2023年   29篇
  2022年   67篇
  2021年   92篇
  2020年   82篇
  2019年   66篇
  2018年   72篇
  2017年   91篇
  2016年   80篇
  2015年   101篇
  2014年   131篇
  2013年   251篇
  2012年   129篇
  2011年   164篇
  2010年   164篇
  2009年   140篇
  2008年   138篇
  2007年   129篇
  2006年   127篇
  2005年   86篇
  2004年   75篇
  2003年   61篇
  2002年   70篇
  2001年   37篇
  2000年   26篇
  1999年   19篇
  1998年   27篇
  1997年   18篇
  1996年   13篇
  1995年   10篇
  1994年   7篇
  1993年   6篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
排序方式: 共有2521条查询结果,搜索用时 15 毫秒
41.
Aim: Oligomannurarate 971 derived from a marine plant has shown neuroprotective effects. In this study we synthesized a series of truncated derivatives of the oligosaccharide, and investigated the effect of these derivatives against Aβ peptide toxicity in vitro. Methods: The sulfoxide method was applied to synthesize the derivatives. SH-SY5Y human neuroblastoma cells were treated with Aβ1-40 (2 pmol/L), and the cell viability was detected using a CCK8 assay. Results: A series of β-(1,4)-D-mannosyl oligosaccharide, ranging from the disaccharide to the hexasaccharide, were synthesized. Addition of 10 pmol/L β-(1,4)-D-mannobiose 6, β-(1,4)-D-mannotriose 9 or β-(1,4)-D-mannotetraose 12 in SH-SY5Y cells significantly attenuated Aβ1-40-induced toxicity. The efficacies were similar to those caused by 10 pmol/L oligomannurarate 971 or alzhemed. Other oligosaccharides including oligomaltoses and oligocelluloses were less active. Conclusion: Synthetic homogeneous short chain β-(1,4)-D-mannans shows neuroprotective effect against Aβ peptide toxicity similar to that of heterogeneous oligomannurarate 971 and alzhemed.  相似文献   
42.
Brachial plexus injury is frequently induced by injuries, accidents or birth trauma. Upper limb function may be partially or totally lost after injury, or left permanently disabled. With the de- velopment of various medical technologies, different types of interventions are used, but their effectiveness is wide ranging. Many repair methods have phasic characteristics, i.e., repairs are done in different phases. This study explored research progress and hot topic methods for pro- tection after brachial plexus injury, by analyzing 1,797 articles concerning the repair of brachial plexus injuries, published between 2004 and 2013 and indexed by the Science Citation Index database. Results revealed that there are many methods used to repair brachial plexus injury, and their effects are varied. Intervention methods include nerve transfer surgery, electrical stimula- tion, cell transplantation, neurotrophic factor therapy and drug treatment. Therapeutic methods in this field change according to the hot topic of research.  相似文献   
43.
Background: Dopamine replacement therapies (levodopa, dopamine receptor agonists, anticholinergics, monoamine oxidase B inhibitors, and catechol-O-methyltransferase inhibitors) remain the cornerstones of therapeutic interventions for Parkinson's disease (PD). Despite the treatment options for PD symptoms, a cure remains elusive. An optimal treatment would be one that combined relief in both motor and nonmotor symptoms with neuroprotective properties. Safinamide is an investigational drug for PD currently in development as add-on therapy to both dopamine agonists and levodopa. Safinamide is a unique molecule with a novel mode of action, targeting both dopaminergic and glutaminergic systems, and potentially provides motor symptom control. Preliminary results from experimental models suggest potential neuroprotective effects. Studies on the potential effects on nonmotor symptoms are ongoing. Objective: To review the mechanism of action and pharmacokinetics, and to evaluate the available clinical safety and efficacy results of safinamide. Methods: A search of the electronic database MEDLINE (PubMed, no time limits) was performed on 14 December 2007. The full text of all citations was obtained for review. Furthermore, two abstracts on safinamide published as proceedings of a European conference were reviewed. Results/conclusion: Safinamide is a promising investigational drug for PD with a novel mode of action. Early reports confirm the potential efficacy of safinamide in PD. Further studies on potential effects on cognition and neuroprotection are needed.  相似文献   
44.
45.
To investigate the molecular mechanism underlying the neuroprotective effect of lithium on cells, in this study, we exposed SH-SY5Y cells to 0.5 mmol/L lithium carbonate(Li2CO2) for 25–50 weeks and then detected the expression levels of some neurobiology related genes and post-translational modifications of stress proteins in SH-SY5Y cells. cDNA arrays showed that pyruvate kinase 2(PKM2) and calmodulin 3(CaM 3) expression levels were significantly down-regulated, phosphatase protein PP2A expression was lightly down-regulated, and casein kinase II(CK2), threonine/tyrosine phosphatase 7(PYST2), and dopamine beta-hydroxylase(DBH) expression levels were significantly up-regulated. Besides, western blot analysis of stress proteins(HSP27, HSP70, GRP78 and GRP94) showed an over-expression of two proteins: a 105 kDa protein which is a hyper-phosphorylated isoform of GRP94, and a 108 kDa protein which is a phosphorylated tetramer of HSP27. These results suggest that the neuroprotective effects of lithium are likely related to gene expressions and post-translational modifications of proteins cited above.  相似文献   
46.
Intracerebral hemorrhage (ICH) is associated with diverse sets of neurological symptoms and prognosis, depending on the site of bleeding. Relative rate of hemorrhage occurring in the cerebral cortex (lobar hemorrhage) has been increasing, but there is no report on effective pharmacotherapeutic approaches for cortical hemorrhage either in preclinical or clinical studies. The present study aimed to establish an experimental model of cortical hemorrhage in mice for evaluation of effects of therapeutic drug candidates. Type VII collagenase at 0.015 U, injected into the parietal cortex, induced hemorrhage expanding into the whole layer of the posterior parts of the sensorimotor cortex in male C57BL/6 mice. Mice with ICH under these conditions exhibited significant motor deficits as revealed by beam‐walking test. Daily administration of nicotine (1 and 2 mg/kg), with the first injection given at 3 hr after induction of ICH, improved motor performance of mice in a dose‐dependent manner, although nicotine did not alter the volume of hematoma. Immunohistochemical examinations revealed that the number of neurons was drastically decreased within the hematoma region. Nicotine at 2 mg/kg partially but significantly increased the number of remaining neurons within the hematoma at 3 days after induction of ICH. ICH also resulted in inflammatory activation of microglia/macrophages in the perihematoma region, and nicotine (1 and 2 mg/kg) significantly attenuated the increase of microglia. These results suggest that nicotine can provide a therapeutic effect on cortical hemorrhage, possibly via its neuroprotective and anti‐inflammatory actions. © 2017 Wiley Periodicals, Inc.  相似文献   
47.
Objective: This study aims to investigate the neuroprotective effect of Rho kinase inhibitor fasudil hydrochloride in ischemia/reperfusion injury N2a neuron. Methods: In vitro, N2a cells induced by ischemia and ischemia-reperfusion were treated with fasudil hydrochloride, cell damage was analyzed by MTT. On the other hand, the cytoskeleton of N2a cells was scanned through immunofluorescence techniques by Confocal Laser Microscopy which stained with FITC-phalloidin for F-actin visualization. Results: The activation of ROCK-II increased significantly in the damaged local during the following phase of ischemia/reperfusion injury. Ischemia induced a striking reorganization of actin cytoskeleton with a weakening of fluorescent intensity of the peripheral filament actin bands and formation of the long and thick stress fibers, but pretreatment of Fasudil hydrochloride could reversed the changes of ultra-structure on the cellular surface. MTT assay showed that Fasudil hydrochloride could prolong the survival time of the N2a cells after mimic ischemia-reperfusion for 24 h. Conclusions: The activation of ROCK-II has an exceptional hoist after ischemia/reperfusion injury, it is likely to induce the collapse of the growth cone through MLC-P. Fasudil hydrochloride could promote axonal growth on inhibitory of ROCK activity.  相似文献   
48.
Increasing evidence indicates that melatonin possesses protective effects toward different kinds of damage in various organs, including the brain. In a neonatal model of hypoxia‐ischemia (HI), melatonin was neuroprotective and preserved the expression of the silent information regulator 1 (SIRT1) 24 hours after the insult. This study aimed to gain more insight into the role of SIRT1 in the protective effect of melatonin after HI by studying the early (1 hour) modulation of SIRT1 and its downstream targets, and the consequences on necrosis, apoptosis, autophagy, and glial cell activation. We found that melatonin administered 5 minutes after the ischemic insult significantly reduced necrotic cell death assessed 1 hour after its administration. In parallel, we found a reduced activation of the early phases of intrinsic apoptosis, detected by reduced BAX translocation to the mitochondria and preservation of the mitochondrial expression of cytochrome C, indicating a reduced outer mitochondrial membrane permeabilization in the melatonin‐treated ischemic animals. These effects were concomitant to increased expression and activity of SIRT1, reduced expression and acetylation of p53, and increased autophagy activation. Melatonin also reduced HI‐induced glial cells activation. SIRT1 was expressed in neurons after HI and melatonin but not in reactive glial cells expressing GFAP. Colocalization between SIRT1 and GFAP was found in some cells in control conditions. In summary, our results provide more insight into the connection between SIRT1 and melatonin in neuroprotection. The possibility that melatonin‐induced SIRT1 activity might contribute to differentiate neuronal progenitor cells during the neurodegenerative process needs to be further investigated.  相似文献   
49.
Arimoclomol, an amplifier of heat shock protein expression involved in cellular stress response, has emerged as a potential therapeutic candidate in amyotrophic lateral sclerosis (ALS) in recent years. Treatment with arimoclomol was reported to improve survival and muscle function in a mouse model of motor neuron disease. Several single- and multiple-dose safety studies have been completed in healthy control subjects. A 3-month Phase IIa study in people with ALS demonstrated safety at dosages up to 300 mg/day and another study is currently recruiting participants with familial ALS caused by mutations in the superoxide dismutase gene. We review the rationale for testing arimoclomol in sporadic and familial ALS in the context of available safety and pharmacokinetic data. Published and unpublished literature relative to the drug in the past two decades is discussed. The current review attempts to bring together our existing understanding of the actions of arimoclomol with the disease profile of ALS. The pharmacological profile of arimoclomol and the available preclinical data make it a promising therapeutic possibility in ALS.  相似文献   
50.
A plasmid for cytoglobin expression, pAcGFP1-C1-cytoglobin, was transfected into SH-SY5Y cells. Cobalt chloride was used to establish a model of hypoxia. Western blotting indicated that cytoglobin was overexpressed and there was low expression of hypoxia-inducible factor-1α in SH-SY5Y cells after transfection. Following cobalt chloride-induced hypoxia, cytoglobin and hypoxia-inducible fac-tor-1α expression gradually increased in SH-SY5Y cells. Flow cytometry showed that with increas-ing duration of hypoxia, the proportion of normal cells significantly diminished in the transfected and non-transfected groups. The proportion of cells in the early stages of apoptosis increased. However, the proportion of apoptotic cells was significantly lower in the transfected group compared with the non-transfected group. These results demonstrate that cytoglobin and hypoxia-inducible factor-1α are strongly up-regulated by hypoxia, and that there is a strong relationship between hy-poxia-inducible factor-1α and cytoglobin during hypoxic injury.  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