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   146421篇
  免费   11366篇
  国内免费   4010篇
耳鼻咽喉   1216篇
儿科学   2589篇
妇产科学   1931篇
基础医学   8846篇
口腔科学   2950篇
临床医学   23821篇
内科学   21939篇
皮肤病学   2346篇
神经病学   7739篇
特种医学   5774篇
外国民族医学   39篇
外科学   13697篇
综合类   20021篇
现状与发展   25篇
一般理论   2篇
预防医学   6547篇
眼科学   2083篇
药学   11001篇
  87篇
中国医学   11669篇
肿瘤学   17475篇
  2024年   122篇
  2023年   2513篇
  2022年   3683篇
  2021年   6159篇
  2020年   6186篇
  2019年   5805篇
  2018年   5445篇
  2017年   5727篇
  2016年   5873篇
  2015年   5592篇
  2014年   10457篇
  2013年   13246篇
  2012年   8399篇
  2011年   9194篇
  2010年   7681篇
  2009年   7052篇
  2008年   7019篇
  2007年   7342篇
  2006年   6556篇
  2005年   5890篇
  2004年   4750篇
  2003年   4348篇
  2002年   3308篇
  2001年   2975篇
  2000年   2485篇
  1999年   1973篇
  1998年   1545篇
  1997年   1290篇
  1996年   1097篇
  1995年   1084篇
  1994年   831篇
  1993年   706篇
  1992年   671篇
  1991年   576篇
  1990年   503篇
  1989年   438篇
  1988年   449篇
  1987年   399篇
  1986年   318篇
  1985年   364篇
  1984年   303篇
  1983年   224篇
  1982年   239篇
  1981年   229篇
  1980年   207篇
  1979年   167篇
  1978年   94篇
  1977年   65篇
  1976年   74篇
  1975年   53篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
目的 分析适量运动对于心房颤动(房颤)患者的运动能力以及远期临床预后的影响。方法 通过检索中国知网,万方,维普,Pubmed,OVID,Cochrane Central Register of Controlled Trials (CENTRAL),web of science数据库,纳入对房颤患者进行适量体育活动干预的临床试验。本研究的主要终点为静息心率,最大心率,6 min步行试验,最大运动功率,全因死亡率以及卒中发生率,用以评估适量运动对房颤患者活动耐力以及预后的影响。结果 本研究共纳入7项试验,2 452例患者,试验组为适量运动干预组,对照组为不活跃组。适量运动并不会显著增加患者的静息心率(MD=-1.68,P=0.70)以及最大心率(RD=9.72,P=0.11)。运动训练可显著提高房颤患者的运动能力,明显增加6 min步行距离(MD=59.07,95%CI=11.70-106.44,P<0.05),并且在一定程度上提高运动功率(MD=17.96,95%CI=-6.30-42.22,P=0.15)。适量运动对房颤患者的远期预后不会造成不良影响,适量运动组对比不活跃组,全因死亡率为15.7% vs 14.2%(RD=0.03,95%CI=-0.18-0.25,P=0.75);卒中发生率5.0% vs 2.9%(RD=0.02,95%CI=-0.06-0.09,P=0.69),两组差异无统计学意义。结论 适量运动可在一定程度上提高房颤患的活动耐力,且不增加卒中以及全因死亡率。  相似文献   
992.
993.
PurposeRisk analysis is required by various laws and regulations in Germany and has an impact on each department of a large clinic. We provide an overview of the relevant laws and regulations in Germany and present the technical and organizational experience of introducing risk analysis in the Department of Radiation Oncology at the Universitätsklinikum Erlangen.MethodsRisk analysis was performed with an in-house developed extension of our intranet platform and ticketing system. Risks were classified according to occurrence and severity, each on a 5-level scale resulting into a risk matrix. An interdisciplinary team of six experienced members formed the core meeting weekly.ResultsA total of 38 risks and 50 measures have been identified in 41 1 h-meetings corresponding to approx. 260 working hours. Risk was distributed 8/20/13 to the categories critical (n = 8), monitoring (n = 20), and conditionally acceptable (n = 13). Risk analysis has been evaluated before and after introducing measures.ConclusionThe risk analysis method introduced has been successfully used in routine operations for over a year. Risk analysis takes time and effort. However, because experts from different disciplines meet each other every week, the overall workflow of the radiation oncology department can be improved efficiently and continuously.  相似文献   
994.
美国食品药品管理局(FDA)于2019年2月发布了"供企业用戒烟及相关适应症:开发尼古丁替代疗法药品的指导原则"(草案)。该指导原则介绍了FDA对尼古丁替代疗法(NRT)药品总体开发方案的建议,而我国目前尚无类似指导原则。介绍该指导原则的主要内容,期待对我国这类药的研发有益。  相似文献   
995.
Introduction: Combination treatment with a BRAF inhibitor and MEK inhibitor is the standard of care for patients with advanced BRAFV600 mutation-positive melanoma. With the currently available combinations of dabrafenib plus trametinib and vemurafenib plus cobimetinib, median progression-free survival (PFS) of over 12 months has been achieved. However, treatment resistance and disease recurrence remain a clinical challenge.

Areas covered: Encorafenib in combination with bimetinib offers a new approach that may offer benefits over existing BRAF/MEK inhibitor combinations.

Expert opinion: While other BRAF/MEK inhibitor combinations have achieved a median overall survival (OS) of 22 months, patients with advanced BRAF mutation-positive melanoma treated with encorafenib plus binimetinib achieved a median OS of 33.6 months in the phase III COLUMBUS trial. PFS also appears to be improved with encorafenib plus binimetinib. This improved efficacy may be related to the distinct pharmacokinetics of encorafenib, with prolonged binding to the target molecule providing greater BRAF inhibition and increased potency compared with other drugs in the same class. Increased specificity of encorafenib may also result in better tolerability with less off-target effects, including reduced occurrence of pyrexia and photosensitivity. Encorafenib plus binimetinib seems likely to emerge as a valuable therapeutic alternative to established BRAF/MEK inhibitor combinations.  相似文献   

996.
Objective: We have previously found that mesenchymal stem cell (MSC) therapy can ameliorate phosgene-induced acute lung injury (ALI). Moreover, exosomes can be used as a cell-free alternative therapy. In the present study, we aimed to assess the effect of MSC-derived exosomes on phosgene-induced ALI.

Methods: MSC-derived exosomes were isolated from MSCs through ultracentrifugation. Sprague-Dawley (SD) rats were exposed to phosgene at 8.33?g/m3 for 5?min. MSC-derived exosomes were intratracheally administered and rats were sacrificed at the time points of 6, 24 and 48?h.

Results: Compared with the phosgene group, MSC-derived exosomes reversed respiratory function alterations, showing increased levels of TV, PIF, PEF and EF50 as well as decreased levels of RI and EEP. Furthermore, MSC-derived exosomes improved pathological alterations and reduced wet-to-dry ratio and total protein content in BALF. MSC-derived exosomes reduced the levels of TNF-α, IL-1β and IL-6 and increased the IL-10 level in BALF and plasma. MSC-derived exosomes suppressed the MMP-9 level and increased the SP-C level.

Conclusions: MSC-derived exosomes exerted beneficial effects on phosgene-induced ALI via modulating inflammation, inhibiting MMP-9 synthesis and elevating SP-C level.  相似文献   

997.
ObjectiveTo propose the Intense Pulsed Light (IPL) therapy as a helpful supplementary treatment in patients with dry eye disease.Material and methodsRetrospective cross sectional design. Medical records of patients in whom dry eye disease symptoms were not satisfactorily controlled with medical therapy alone and who underwent additional IPL with at least three sessions completed. Data were analyzed before therapy and 3 weeks after its completion to asses improvement. Determination of symptoms, through a visual analog scale; tear film stability, through tear Break Up Time (tBUT); measurement of tear secretion, through Schirmer Test; and ocular surface staining with Van Bijsterveld score were evaluated. SPSS software and nonparametric analysis of repeated measures were used. The study was approved by the ethics committee.Results50 eyes from 25 subjects were reviewed. There were 9 males (36%) and 16 females (64%), with a median age of 59 years (IQR 52-64). The median of the symptoms scale was 8 (IQR 8-9) and 3 (IQR 2-4) before and after the therapy respectively (P < .05). The median of BUT was 4 (IQR 3-5) and 10 (IQR 8-11), Schirmer test was 13 (IQR 12-15) and 15 (IQR 13-20), and Van Bijsterveld score was 3 (RIC 3-4) and 2 (IQR 2-3) before and after the therapy respectively (P < .05, for all measurements).ConclusionIPL treatment has excellent results regarding both: dry eye disease symptoms improvement and in office objective tests such as tBUT, Schirmer test and Van Bijsterveld score; IPL could be considered as an effective adjunct for dry eye disease.  相似文献   
998.

Background

As a recently discovered adipokine, nesfatin-1 is conducive to insulin sensitivity, lipid profile, energy balance, and probably obesity.

Objective

The aim of the present study was to investigate the effect of upper-body resistance exercise training (RET) on nesfatin-1 levels, insulin resistance, lipid profile, and body composition in obese paraplegic men.

Methods

Twenty obese paraplegic men were randomly assigned into control and upper-body RET groups. Upper-body RET was performed for 8 weeks, 3 sessions per week at an intensity corresponding to 60–80% maximum amount of force that can be generated in one maximal contraction in 5 stations (bench press, seated rows, sitting lat pulldown, arm extension, and arm curls). Body fat percentage was determined according to 4-sites skinfold protocol of Durnin and Womersley and Siri equation. Obesity for spinal cord injury patients in the current study was set at BMI >22?kg/m2. Data were statistically analyzed by paired and independent t-test (P?<?0.05).

Results

We found significant improvements in serum levels of nesfatin-1 (21.13%), insulin sensitivity (8.95%), and high-density lipoprotein (10.87%). Other lipid profile markers, i.e. low-density lipoprotein (4.32%), cholesterol (8.20%), and triglyceride (15.10%) reduced significantly after upper-body RET. Moreover, upper-body RET led to a significant reduction in body mass index (2.36%), body fat percentage (2.79%), and waist-to-hip ratio (2.40%).

Conclusion

Upper-body RET improved insulin sensitivity, lipid profile, and body composition in paraplegic men. Serum nefastin-1 may be a potential marker of success in weight management in this population.  相似文献   
999.
Background: Acute exercise can increase motor cortical excitability and enhance motor learning in healthy individuals, an effect known as exercise priming. Whether it has the same effects in people with stroke is unclear.

Objectives: The objective of this study was to investigate whether a short, clinically-feasible high-intensity exercise protocol can increase motor cortical excitability in non-exercised muscles of chronic stroke survivors.

Methods: Thirteen participants with chronic, unilateral stroke participated in two sessions, at least one week apart, in a crossover design. In each session, they underwent either high-intensity lower extremity exercise or quiet rest. Motor cortical excitability of the extensor carpi radialis muscles was measured bilaterally with transcranial magnetic stimulation before and immediately after either exercise or rest. Motor cortical excitability changes (post-exercise or rest measures normalized to pre-test measures) were compared between exercise vs. rest conditions.

Results: All participants were able to reach the target high-intensity exercise level. Blood lactate levels increased significantly after exercise (p < .001, d = 2.85). Resting motor evoked potentials from the lesioned hemisphere increased after exercise (mean 1.66; 95% CI: 1.19, 2.13) compared to the rest condition (mean 1.23; 95% CI: 0.64, 1.82), p = .046, d = 2.76, but this was not the case for the non-lesioned hemisphere (p = .406, d = 0.25).

Conclusions: High-intensity exercise can increase lesioned hemisphere motor cortical excitability in a non-exercised muscle post-stroke. Our short and clinically-advantageous exercise protocol shows promise as a potential priming method in stroke rehabilitation.  相似文献   

1000.
BackgroundThe efficacy of ticagrelor in the long-term post–ST-segment elevation myocardial infarction (STEMI) treated with fibrinolytic therapy remains uncertain.ObjectivesThe purpose of this study was to evaluate the efficacy of ticagrelor when compared with clopidogrel in STEMI patients treated with fibrinolytic therapy.MethodsThis international, multicenter, randomized, open-label with blinded endpoint adjudication trial enrolled 3,799 patients (age <75 years) with STEMI receiving fibrinolytic therapy. Patients were randomized to ticagrelor (180-mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300- to 600-mg loading dose, 75 mg daily thereafter). The key outcomes were cardiovascular mortality, myocardial infarction, or stroke, and the same composite outcome with the addition of severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events at 12 months.ResultsThe combined outcome of cardiovascular mortality, myocardial infarction, or stroke occurred in 129 of 1,913 patients (6.7%) receiving ticagrelor and in 137 of 1,886 patients (7.3%) receiving clopidogrel (hazard ratio: 0.93; 95% confidence interval: 0.73 to 1.18; p = 0.53). The composite of cardiovascular mortality, myocardial infarction, stroke, severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events occurred in 153 of 1,913 patients (8.0%) treated with ticagrelor and in 171 of 1,886 patients (9.1%) receiving clopidogrel (hazard ratio: 0.88; 95% confidence interval: 0.71 to 1.09; p = 0.25). The rates of major, fatal, and intracranial bleeding were similar between the ticagrelor and clopidogrel groups.ConclusionAmong patients age <75 years with STEMI, administration of ticagrelor after fibrinolytic therapy did not significantly reduce the frequency of cardiovascular events when compared with clopidogrel. (Ticagrelor in Patients With ST Elevation Myocardial Infarction Treated With Pharmacological Thrombolysis [TREAT]; NCT02298088)  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