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   629篇
  免费   41篇
  国内免费   4篇
耳鼻咽喉   5篇
儿科学   8篇
妇产科学   8篇
基础医学   94篇
口腔科学   15篇
临床医学   50篇
内科学   152篇
皮肤病学   11篇
神经病学   35篇
特种医学   27篇
外科学   114篇
综合类   11篇
预防医学   45篇
眼科学   14篇
药学   33篇
中国医学   4篇
肿瘤学   48篇
  2024年   2篇
  2023年   1篇
  2022年   22篇
  2021年   35篇
  2020年   19篇
  2019年   36篇
  2018年   28篇
  2017年   20篇
  2016年   17篇
  2015年   38篇
  2014年   38篇
  2013年   41篇
  2012年   49篇
  2011年   48篇
  2010年   34篇
  2009年   23篇
  2008年   35篇
  2007年   36篇
  2006年   33篇
  2005年   24篇
  2004年   24篇
  2003年   19篇
  2002年   15篇
  2001年   4篇
  2000年   2篇
  1999年   5篇
  1998年   5篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   3篇
  1992年   3篇
  1988年   2篇
  1987年   3篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
排序方式: 共有674条查询结果,搜索用时 31 毫秒
1.
Testicular torsion/detorsion is one of the important emergencies that requires fast surgical intervention. This study aimed to investigate the effects of Salvia miltiorrhiza hydroalcoholic extract combined with verapamil on testicular ischaemia/reperfusion damage in Wistar albino rats. All animals were distributed in 3 groups (n = 8), including the sham-operated group, torsion/detorsion (TD) group and torsion/detorsion + pretreatment with 200 mg/kg Salvia miltiorrhiza extract combined with 0.3 mg/kg verapamil (SMV) group. Oxidative stress biomarkers (MDA, GPx, CAT and TAC) both in plasma and testicular tissue, sperm parameters (motility, vitality, concentration and morphology) and histopathological parameters (MSTD, GECT, Johnson's score, Cosentino's score and testicular cell thickness) were assessed in all groups. Ischaemia/reperfusion significantly increased MDA and decreased GPx, CAT and TAC levels (p < .05). Pretreatment with SMV significantly increased GPx, CAT and TAC levels (p < .05). SMV group increased progressive sperm motility and vitality and reduced non-progressive motility of spermatozoon (p < .05). Testicular torsion significantly decreased all histopathological parameters compared to the sham group (p < .05). SMV pretreatment remarkably increased MSTD, GECT and Cosentino's score in comparison with the TD group (p < .05). A combination of Salvia miltiorrhiza with verapamil could reduce damages triggered by testicular torsion detorsion and improve sperm functionality parameters and oxidative stress defence systems.  相似文献   
2.
Induction of oxidative stress during the sperm preparation process for assisted reproductive techniques (ART) in men can weaken sperm parameters. Vitamin E (VE) is considered a factor in boosting male fertility. This experimental study (in vitro) aimed to assess the impact of VE supplementation on sperm quality and lipid peroxidation during sperm sampling at different times. For this mention, semen samples were collected from 50 asthenoteratozoospermic men. Samples were divided into control and test groups for 2, 4 and 6 hr that the test group was incubated with VE (2 mM). In two groups, total motility, progressive motility and viability based on the WHO 2010 criteria were assessed. Moreover, malondialdehyde (MDA) levels were evaluated in each group. In the control group, total and progressive motility and sperm viability were decreased significantly after 2 hr; however, MDA levels were increased significantly after 6 hr. Also, in the test group, sperm parameters were increased significantly after 2 hr, and MDA levels were decreased significantly after 6 hr compared to the control group. In outcome, in vitro VE supplementation may protect spermatozoa from the adverse effect of oxidative stress during sperm preparation via preservation antioxidant processes in normal condition.  相似文献   
3.
Post‐traumatic arthritis (PTA) frequently develops after intra‐articular fracture of weight bearing joints. Loss of cartilage viability and post‐injury inflammation have both been implicated as possible contributing factors to PTA progression. To further investigate chondrocyte response to impact and fracture, we developed a blunt impact model applying 70%, 80%, or 90% surface‐to‐surface compressive strain with or without induction of an articular fracture in a cartilage explant model. Following mechanical loading, chondrocyte viability, and apoptosis were assessed. Culture media were evaluated for the release of double‐stranded DNA (dsDNA) and immunostimulatory activity via nuclear factor kappa B (NF‐κB) activity in Toll‐like receptor (TLR) ‐expressing Ramos‐Blue reporter cells. High compressive strains, with or without articular fracture, resulted in significantly reduced chondrocyte viability. Blunt impact at 70% strain induced a loss in viability over time through a combination of apoptosis and necrosis, whereas blunt impact above 80% strain caused predominantly necrosis. In the fracture model, a high level of primarily necrotic chondrocyte death occurred along the fracture edges. At sites away from the fracture, viability was not significantly different than controls. Interestingly, both dsDNA release and NF‐κB activity in Ramos‐Blue cells increased with blunt impact, but was only significantly increased in the media from fractured cores. This study indicates that the mechanism of trauma determines the type of chondrocyte death and the potential for post‐injury inflammation. (c) 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1283–1292, 2013  相似文献   
4.
With the successful uptake and inclusion of robotic systems in minimally invasive surgery and with the increasing application of robotic surgery (RS) in numerous surgical specialities worldwide, there is now a need to develop and enhance the technology further. One such improvement is the implementation and amalgamation of haptic feedback technology into RS which will permit the operating surgeon on the console to receive haptic information on the type of tissue being operated on. The main advantage of using this is to allow the operating surgeon to feel and control the amount of force applied to different tissues during surgery thus minimising the risk of tissue damage due to both the direct and indirect effects of excessive tissue force or tension being applied during RS. We performed a two-rater systematic review to identify the latest developments and potential avenues of improving technology in the application and implementation of haptic feedback technology to the operating surgeon on the console during RS. This review provides a summary of technological enhancements in RS, considering different stages of work, from proof of concept to cadaver tissue testing, surgery in animals, and finally real implementation in surgical practice. We identify that at the time of this review, while there is a unanimous agreement regarding need for haptic and tactile feedback, there are no solutions or products available that address this need. There is a scope and need for new developments in haptic augmentation for robot-mediated surgery with the aim of improving patient care and robotic surgical technology further.  相似文献   
5.
The development of regenerative therapies for cartilage injury has been greatly aided by recent advances in stem cell biology. Induced pluripotent stem cells (iPSCs) have the potential to provide an abundant cell source for tissue engineering, as well as generating patient-matched in vitro models to study genetic and environmental factors in cartilage repair and osteoarthritis. However, both cell therapy and modeling approaches require a purified and uniformly differentiated cell population to predictably recapitulate the physiological characteristics of cartilage. Here, iPSCs derived from adult mouse fibroblasts were chondrogenically differentiated and purified by type II collagen (Col2)-driven green fluorescent protein (GFP) expression. Col2 and aggrecan gene expression levels were significantly up-regulated in GFP+ cells compared with GFP− cells and decreased with monolayer expansion. An in vitro cartilage defect model was used to demonstrate integrative repair by GFP+ cells seeded in agarose, supporting their potential use in cartilage therapies. In chondrogenic pellet culture, cells synthesized cartilage-specific matrix as indicated by high levels of glycosaminoglycans and type II collagen and low levels of type I and type X collagen. The feasibility of cell expansion after initial differentiation was illustrated by homogenous matrix deposition in pellets from twice-passaged GFP+ cells. Finally, atomic force microscopy analysis showed increased microscale elastic moduli associated with collagen alignment at the periphery of pellets, mimicking zonal variation in native cartilage. This study demonstrates the potential use of iPSCs for cartilage defect repair and for creating tissue models of cartilage that can be matched to specific genetic backgrounds.  相似文献   
6.
β-Carbolines (BCs) are considered to be endogenous toxins and have been proposed as possible causative candidates inducing Parkinson's disease (PD). However, there is controversy about the effect and also effective dose of these compounds in the etiology of PD. This study was designed to further examine the effect of norharman (NH), a BC which in mammalian brain occurs at high levels in the substantia nigra, on the development of Parkinsonism-like behaviors in rats. A small amount (4μl) of NH solution at 2 or 200ng/ml was unilaterally injected into either striatum or substantia nigra (SN) by stereotaxic surgery. The development of Parkinsonism was assessed by three conventional behavioral tests, compared to the effects of unilateral 6-hydroxydopamine (6-OHDA) - induced lesions in the nigrostriatal pathway. An apomorphine-induced rotational test revealed no Parkinsonism-like behavior in the NH treated groups. However, rats that received the high concentration of NH into their SN showed significant biased swings in the elevated body swing test. In a rotarod test, NH treated groups showed relatively weak motor performance and their learning patterns were close to that of the 6-OHDA treated rats. Considering that the rotational test is only valid in animals with severe Parkinsonism, but time spent on the rotating rod correlates inversely with severity of Parkinsonism, our results indicate that a single exposure to low amounts of NH is effective in producing moderate Parkinsonism-like behavioral symptoms, possibly through a neurotoxic effect of this agent on the SN dopaminergic neurons.  相似文献   
7.
During January 2013–August 2014, a total of 1,800 patients in Iran who had respiratory illness were tested for Middle East respiratory syndrome coronavirus. A cluster of 5 cases occurred in Kerman Province during May–July 2014, but virus transmission routes for some infections were unclear.  相似文献   
8.
Pituitary - To review our institutional experience with the&nbsp;surgical management of prolactinomas through the endoscopic endonasal approach with specific focus on cavernous sinus invasion....  相似文献   
9.
BACKGROUNDPatients with p16+ oropharyngeal squamous cell carcinoma (OPSCC) are potentially cured with definitive treatment. However, there are currently no reliable biomarkers of treatment failure for p16+ OPSCC. Pathologist-based visual assessment of tumor cell multinucleation (MN) has been shown to be independently prognostic of disease-free survival (DFS) in p16+ OPSCC. However, its quantification is time intensive, subjective, and at risk of interobserver variability.METHODSWe present a deep-learning–based metric, the multinucleation index (MuNI), for prognostication in p16+ OPSCC. This approach quantifies tumor MN from digitally scanned H&E-stained slides. Representative H&E-stained whole-slide images from 1094 patients with previously untreated p16+ OPSCC were acquired from 6 institutions for optimization and validation of the MuNI.RESULTSThe MuNI was prognostic for DFS, overall survival (OS), or distant metastasis–free survival (DMFS) in p16+ OPSCC, with HRs of 1.78 (95% CI: 1.37–2.30), 1.94 (1.44–2.60), and 1.88 (1.43–2.47), respectively, independent of age, smoking status, treatment type, or tumor and lymph node (T/N) categories in multivariable analyses. The MuNI was also prognostic for DFS, OS, and DMFS in patients with stage I and stage III OPSCC, separately.CONCLUSIONMuNI holds promise as a low-cost, tissue-nondestructive, H&E stain–based digital biomarker test for counseling, treatment, and surveillance of patients with p16+ OPSCC. These data support further confirmation of the MuNI in prospective trials.FUNDINGNational Cancer Institute (NCI), NIH; National Institute for Biomedical Imaging and Bioengineering, NIH; National Center for Research Resources, NIH; VA Merit Review Award from the US Department of VA Biomedical Laboratory Research and Development Service; US Department of Defense (DOD) Breast Cancer Research Program Breakthrough Level 1 Award; DOD Prostate Cancer Idea Development Award; DOD Lung Cancer Investigator-Initiated Translational Research Award; DOD Peer-Reviewed Cancer Research Program; Ohio Third Frontier Technology Validation Fund; Wallace H. Coulter Foundation Program in the Department of Biomedical Engineering; Clinical and Translational Science Award (CTSA) program, Case Western Reserve University; NCI Cancer Center Support Grant, NIH; Career Development Award from the US Department of VA Clinical Sciences Research and Development Program; Dan L. Duncan Comprehensive Cancer Center Support Grant, NIH; and Computational Genomic Epidemiology of Cancer Program, Case Comprehensive Cancer Center. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH, the US Department of VA, the DOD, or the US Government.  相似文献   
10.
Journal of Digital Imaging - Accurate information of the lung shape analysis and its anatomical variations is very noticeable in medical imaging. The normal variations of the lung shape can be...  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