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   6697篇
  免费   545篇
  国内免费   244篇
耳鼻咽喉   29篇
儿科学   73篇
妇产科学   87篇
基础医学   614篇
口腔科学   112篇
临床医学   494篇
内科学   932篇
皮肤病学   275篇
神经病学   380篇
特种医学   98篇
外科学   315篇
综合类   722篇
一般理论   1篇
预防医学   828篇
眼科学   141篇
药学   1636篇
  2篇
中国医学   567篇
肿瘤学   180篇
  2024年   8篇
  2023年   113篇
  2022年   146篇
  2021年   270篇
  2020年   270篇
  2019年   254篇
  2018年   253篇
  2017年   255篇
  2016年   271篇
  2015年   259篇
  2014年   392篇
  2013年   545篇
  2012年   429篇
  2011年   418篇
  2010年   359篇
  2009年   361篇
  2008年   332篇
  2007年   334篇
  2006年   274篇
  2005年   232篇
  2004年   206篇
  2003年   180篇
  2002年   146篇
  2001年   143篇
  2000年   100篇
  1999年   87篇
  1998年   79篇
  1997年   66篇
  1996年   55篇
  1995年   61篇
  1994年   73篇
  1993年   52篇
  1992年   49篇
  1991年   56篇
  1990年   47篇
  1989年   34篇
  1988年   34篇
  1987年   35篇
  1986年   25篇
  1985年   38篇
  1984年   36篇
  1983年   17篇
  1982年   19篇
  1981年   20篇
  1980年   17篇
  1979年   10篇
  1978年   8篇
  1977年   5篇
  1976年   6篇
  1972年   3篇
排序方式: 共有7486条查询结果,搜索用时 31 毫秒
1.
目的糖基化终末产物(AGEs)在糖尿病患者在角膜外伤或接受角膜手术时极易出现角膜上皮愈合延迟甚至不愈的过程中起着关键作用,本文研究维生素A(VA)对以糖基化终末产物AGE-BSA诱导角膜上皮细胞损伤的影响及可能的作用机制。方法以HCE-2细胞为研究对象,AGE-BSA为诱导剂,试剂盒检测VA对细胞凋亡率及线粒体膜电位的影响,荧光显微镜检测细胞内凋亡小体,Western blot检测相关的蛋白表达量。结果VA抑制AGE-BSA诱导的HCE细胞凋亡,调节AGEBSA引起的凋亡相关蛋白的变化。同时,VA与JNK的抑制剂同等程度的减少AGE-BSA诱导的JNK和NF-κB的磷酸化。结论VA可能通过抑制JNK介导的NF-κB炎症通路而起到减少AGE-BSA诱导的角膜上皮细胞凋亡的作用,可以作为糖尿病患者角膜上皮损伤的保护剂。  相似文献   
2.
3.
4.
IntroductionTraining fires may constitute a major portion of some firefighters’ occupational exposures to smoke. However, the magnitude and composition of those exposures are not well understood and may vary by the type of training scenario and fuels.ObjectivesTo understand how structure fire training contributes to firefighters' and instructors’ select chemical exposures, we conducted biological monitoring during exercises involving combustion of pallet and straw and oriented strand board (OSB) or the use of simulated smoke.MethodsUrine was analyzed for metabolites of polycyclic aromatic hydrocarbons (PAHs) and breath was analyzed for volatile organic compounds (VOCs) including benzene.ResultsMedian concentrations of nearly all PAH metabolites in urine increased from pre-to 3-hr post-training for each scenario and were highest for OSB, followed by pallet and straw, and then simulated smoke. For instructors who supervised three trainings per day, median concentrations increased at each collection. A single day of OSB exercises led to a 30-fold increase in 1-hydroxypyrene for instructors, culminating in a median end-of-shift concentration 3.5-fold greater than median levels measured from firefighters in a previous controlled-residential fire study. Breath concentrations of benzene increased 2 to 7-fold immediately after the training exercises (with the exception of simulated smoke training). Exposures were highest for the OSB scenario and instructors accumulated PAHs with repeated daily exercises.ConclusionsDermal absorption likely contributed to the biological levels as the respiratory route was well protected. Training academies should consider exposure risks as well as instructional objectives when selecting training exercises.  相似文献   
5.
对药品实行注册管理制度是确保公众健康的全球通用的监管措施。中药作为承载中医药理论与用药实践的主要载体,对中药产品的注册管理又具有其特殊性。2017年正式实施的《中医药法》提出了建立符合中医药特点管理制度的发展方针,研究制定配套文件或修订现行规章以适应衔接其立法精神是当前重要的现实问题之一。欧盟在植物药监管领域取得了良好成效,本文旨在系统分析欧盟对其注册管理的法规体系,深入剖析其监管特点和对中国中药注册管理的启示,以期为当前《中医药法》背景下中药监管制度的改革提供参考。  相似文献   
6.
Purpose: To study the prevalence and time of onset of ocular complications in intermediate uveitis (IU) and to assess their effects on visual outcome in short-term and long-term follow-up.

Methods: A retrospective cohort study of patients with IU who had a minimal follow-up of one year.

Results: 96 patients (174 eyes, 70% females) were included with a mean age at presentation of 30 years. Children constituted 38% of all patients. Mean follow- up was 64.9 months. Pars planitis was the most common form followed by sarcoidosis and multiple sclerosis. Cystoid macular edema (CME), cataract, epiretinal membrane and posterior synechiae were the most prevalent complications. Posterior synechiae, band keratopathy, cataract and papillitis at presentation were associated with worse presenting visual acuity (VA). Of the late-onset complications, glaucoma/ocular hypertension (OHT) was the most significantly associated with worse long-term VA. Most sight-threatening complications (namely CME and glaucoma) were diagnosed at presentation while late complications predominantly affected the posterior segment and included among others peripheral retinal elevations, vasoproliferative tumors, and vitreous hemorrhage. Median LogMAR VA improved at short-term and long-term follow-up, from 0.2 to 0.1 (p<0.001). Subgroup analysis revealed significant VA improvement for eyes with all the different complications except for eyes with glaucoma/OHT.

Conclusion: IU is a chronic low-grade uveitis that may be associated with protean early and late complications of the anterior or posterior segments or both. Optimal treatment regimens are imperative for the strict control of inflammation and proper management of complications thus allowing a favorable long-term prognosis.  相似文献   

7.
The main aim of the paper is to discuss current knowledge on how Age Related Macular Degeneration (AMD) affects Dark Adaptation (DA). The paper is divided into three parts. Firstly, we outline some of the molecular mechanisms that control DA. Secondly, we review the psychophysical issues and the corresponding analytical techniques. Finally, we characterise the link between slowed DA and the morphological abnormalities in early AMD.Historically, DA has been regarded as too cumbersome for widespread clinical application. Yet the technique is extremely useful; it is widely accepted that the psychophysically obtained slope of the second rod-mediated phase of the dark adaptation function is an accurate assay of photoreceptor pigment regeneration kinetics. Technological developments have prompted new ways of generating the DA curve, but analytical problems remain. A simple potential solution to these, based on the application of a novel fast mathematical algorithm, is presented. This allows the calculation of the parameters of the DA curve in real time.Improving current management of AMD will depend on identifying a satisfactory endpoint for evaluating future therapeutic strategies. This must be implemented before the onset of severe disease. Morphological changes progress too slowly to act as a satisfactory endpoint for new therapies whereas functional changes, such as those seen in DA, may have more potential in this regard. It is important to recognise, however, that the functional changes are not confined to rods and that building a mathematical model of the DA curve enables the separation of rod and cone dysfunction and allows more versatility in terms of the range of disease severity that can be monitored. Examples are presented that show how analysing the DA curve into its constituent components can improve our understanding of the morphological changes in early AMD.  相似文献   
8.
《Neuromodulation》2021,24(2):353-360
ObjectivesPatients with essential tremor treated with thalamic deep brain stimulation may experience increased tremor with the progression of their disease. Initially, this can be counteracted with increased stimulation. Eventually, this may cause unwanted side-effects as the circumferential stimulation from a standard ring contact spreads into adjacent regions. Directional leads may offer a solution to this clinical problem. We aimed to compare the ability of a standard and a directional system to reduce tremor without side-effects and to improve the quality of life for patients with advanced essential tremor.Materials and MethodsSix advanced essential tremor patients with bilateral thalamic deep brain stimulation had their standard system replaced with a directional system. Tremor rating scale scores were prospectively evaluated before and after the replacement surgery. Secondary analyses of quality of life related to tremor, voice, and general health were assessed.ResultsThere was a significantly greater reduction in tremor without side-effects (p = 0.017) when using the directional system. There were improvements in tremor (p = 0.031) and voice (p = 0.037) related quality of life but not in general health for patients using optimized stimulation settings with the directional system compared to the standard system.ConclusionsIn this cohort of advanced essential tremor patients who no longer had ideal tremor reduction with a standard system, replacing their deep brain stimulation with a directional system significantly improved their tremor and quality of life. Up-front implantation of directional deep brain stimulation leads may provide better tremor control in those patients who progress at a later time point.  相似文献   
9.
BackgroundRubeosis faciei diabeticorum is a persistent facial erythema in patients with diabetes mellitus. The actual pathogenesis has not been studied. However, it is speculated to be a cutaneous diabetic microangiopathy.ObjectiveExamine the correlation between the severity of facial erythema and the possible causes of microvascular diabetic complications, namely oxidative stress, hyperglycemia, and cutaneous accumulation of advanced glycation end-products .MethodsPatients diagnosed with Type 2 diabetes mellitus (n = 32) were enrolled in the study. The facial erythema index was measured using the Mexameter MX18; cutaneous accumulation of advanced glycation end-products was estimated by measuring skin auto fluorescence with the AGE Reader (DiagnOptics Technologies B.V. – Groningen, Netherlands). Glycated haemoglobin, total antioxidant status, and malondialdehyde were measured in blood by TBARS assay. The correlation between the selected variables was assessed by Spearman's rank test; p  0.05 was considered statistically significant.ResultsThere was a statistically significant correlation between total antioxidant status and the facial erythema index (ρ = 0.398, p = 0.024). Malondialdehyde, skin autofluorescence, glycated haemoglobin, body mass index, duration of diabetes, and age did not demonstrate statistically significant correlation with the facial erythema index.Study limitationsThis is an observational study. Elevation of total antioxidant status could have been caused by several factors that might have also influenced the development of rubeosis faciei, including hyperbilirubinemia and hyperuricemia.ConclusionsThe results contradicted expectations. Total antioxidant status correlated positively with facial erythema index; however, there was no correlation with oxidative stress and skin autofluorescence. Further investigations should be conducted to reveal the cause of total antioxidant status elevation in patients with rubeosis faciei.  相似文献   
10.
BackgroundBreastfeeding women often use herbal products to increase their milk supply. The aim of this study was to summarize the literature about the role of healthcare providers in advising breastfeeding women about herbal product use.MethodsPubmed, ScienceDirect, Web of Science, and CINAHL databases were searched for articles written in English using the Keywords: “breastfeeding” or “lactation” and “herbal medicine*“, “botanical*“, “dietary supplement*“, “natural product*“, “traditional medicine*” or “complementary medicine*“.ResultsTwenty-two articles were included in this review. A lack of inter-professional communication and guidelines, a lack of provider confidence and knowledge about the evidence for the efficacy and safety of herbal products were identified as causing a ‘gap’ between current practice and expectations of breastfeeding women seeking advice about their use herbal products.ConclusionsStrategic and collaborative efforts between key stakeholders are required to ensure the needs of women who are considering herbal product use while breastfeeding are met.  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