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   45859篇
  免费   3490篇
  国内免费   1962篇
耳鼻咽喉   13篇
儿科学   363篇
妇产科学   66篇
基础医学   2097篇
口腔科学   198篇
临床医学   6587篇
内科学   20435篇
皮肤病学   85篇
神经病学   733篇
特种医学   1786篇
外科学   2352篇
综合类   8985篇
现状与发展   6篇
预防医学   1402篇
眼科学   32篇
药学   3798篇
  41篇
中国医学   2265篇
肿瘤学   67篇
  2024年   81篇
  2023年   760篇
  2022年   1092篇
  2021年   2135篇
  2020年   1914篇
  2019年   1584篇
  2018年   1636篇
  2017年   1399篇
  2016年   1453篇
  2015年   1557篇
  2014年   3249篇
  2013年   3430篇
  2012年   2771篇
  2011年   2972篇
  2010年   2417篇
  2009年   2267篇
  2008年   2438篇
  2007年   2542篇
  2006年   2166篇
  2005年   1884篇
  2004年   1499篇
  2003年   1256篇
  2002年   1073篇
  2001年   955篇
  2000年   709篇
  1999年   622篇
  1998年   665篇
  1997年   694篇
  1996年   499篇
  1995年   483篇
  1994年   388篇
  1993年   386篇
  1992年   320篇
  1991年   273篇
  1990年   218篇
  1989年   204篇
  1988年   202篇
  1987年   174篇
  1986年   123篇
  1985年   179篇
  1984年   127篇
  1983年   83篇
  1982年   106篇
  1981年   87篇
  1980年   57篇
  1979年   50篇
  1978年   32篇
  1977年   35篇
  1976年   23篇
  1975年   20篇
排序方式: 共有10000条查询结果,搜索用时 590 毫秒
41.
42.
Introduction: It is important to know how to treat hypertension in patients with coronary artery disease (CAD). The reason for the review was to update this treatment and to discuss the 2015 American Heart Association/American College of Cardiology/American Society of Hypertension 2015 guidelines of treatment of hypertension in patients with CAD.

Areas covered: Studies between 1968 and 2015 were reviewed on treatment of hypertension in patients with CAD using a Medline search, and studies between 1977 and 2015 were reported. Hypertension should be treated with beta blockers and ACE inhibitors or angiotensin receptor blockers (ARBs). Long-acting nitrates are effective antianginal and anti-ischemic drugs. Calcium-channel blockers (CCBs) may be added if angina persists despite beta blockers and long-acting nitrates. The 2015 guidelines recommend that the blood pressure should be < 140/90 mm Hg in patients aged ≤ 80 years and the systolic blood pressure < 150 mm Hg if they are ≥ 80 years.

Expert opinion: Hypertension in patients with CAD should be treated with beta blockers and ACE inhibitors or ARBs. Long-acting nitrates are effective antianginal and anti-ischemic drugs. CCBs may be added if angina persists despite beta blockers and long-acting nitrates. The blood pressure should be < 140/90 mm Hg in patients aged < 80 years and the systolic blood pressure < 150 mm Hg if they are ≥ 80 years.  相似文献   
43.

Background

Etomidate is frequently selected over propofol for induction of anaesthesia because of a putatively favourable haemodynamic profile, but data confirming this perception are limited.

Methods

Patients undergoing cardiac surgery were randomised to induction of anaesthesia with propofol or etomidate. Phase I (n=75) was conducted as open-label, whereas Phase II (n=75) was double blind. Mean arterial blood pressure (MAP) and boluses of vasopressor administered after induction were recorded. The primary endpoint was the area under the curve below baseline MAP (MAP-time integral) during the 10 min after induction. Secondary endpoints were the use of vasopressors over the same period, and the effect of blinding on the aforementioned endpoints. Groups were compared using regression models with phase and anaesthetist as factors.

Results

The mean difference between etomidate and propofol in the MAP-time integral below baseline was 2244 mm Hg s (95% confidence interval, 581–3906; P=0.009), representing a 34% greater reduction with propofol. Overall, vasopressors were used in 10/75 patients in the etomidate group vs 21/75 in the propofol group (P=0.38), and in 20/74 patients during the blinded phase vs 11/76 during the open-label phase (P=0.31). The interaction between randomisation and phase (open-labelled or blinded) was not significant for either primary (P=0.73) or secondary endpoints (P=0.90).

Conclusions

Propofol caused a 34% greater reduction in MAP-time integral from baseline after induction of anaesthesia than etomidate, despite more frequent use of vasopressors with propofol, confirming the superior haemodynamic profile of etomidate in this context. The proportion of patients receiving vasopressors increased slightly, albeit not significantly, in both groups in the blinded phase.

Clinical trial registration

Australian and New Zealand Clinical Trials Registry, ACTRN12614000717651.  相似文献   
44.

Background

Acute myocardial infarction (AMI) causes irreversible myocardial damage and release of inflammatory mediators, including cytokines, chemokines and miRNAs. We aimed to investigate changes in the levels of cytokines (IL-6, TNF-α and IL-10), miRNAs profiles (miR-146 and miR-155) and distribution of different monocyte subsets (CD14++CD16-, CD14++CD16+, CD14+CD16++) in the acute and post-healing phases of AMI.

Methods

In eighteen consecutive AMI patients (mean age 56.78?±?12.4 years, mean left ventricle ejection fraction – LVEF: 41.9?±?9.8%), treated invasively, monocyte subsets frequencies were evaluated (flow cytometry), cytokine concentrations were analyzed (ELISA) as well as plasma miRNAs were isolated twice – on admission and after 19.2?±?5.9 weeks of follow-up. Measurements were also performed among healthy volunteers.

Results

AMI patients presented significantly decreased frequencies of classical cells in comparison to healthy controls (median 71.22% [IQR: 64.4–79.04] vs. 84.35% [IQR: 81.2–86.7], p?=?0.001) and higher percent of both intermediate and non-classical cells, yet without statistical significance (median 6.54% [IQR: 5.14–16.64] vs. 5.87% [IQR: 4.48–8.6], p?=?0.37 and median 5.99% [IQR: 3.39–11.5] vs. 5.26% [IQR: 3.62–6.2], p?=?0.42, respectively). In AMI patients both, analyzed plasma miRNA concentrations were higher than in healthy subjects (miR-146: median 5.48 [IQR: 2.4–11.27] vs. 1.84 [IQR: 0.87–2.53], p?=?0.003; miR-155: median 25.35 [IQR: 8.17–43.15] vs. 8.4 [IQR: 0.08–16.9], p?=?0.027, respectively), and returned back to the values found in the control group in follow-up. miR-155/miR-146 ratio correlated with the frequencies of classical monocytes (r=0.6, p?=?0.01) and miR-155 correlated positively with the concentration of inflammatory cytokines ? IL-6 and TNF-α.

Conclusions

These results may suggest cooperation of both pro-inflammatory and anti-inflammatory signals in AMI in order to promote appropriate healing of the infarcted myocardium.  相似文献   
45.
《Vaccine》2016,34(50):6316-6322
ObjectiveAir pollution, weather condition and influenza are known risk factors of acute coronary syndrome (ACS) among elderly people. The influenza vaccine (IV) has been shown to reduce major cardiovascular events. The purpose of this study was to compare resistance to air pollution and weather factors causing ACS between vaccinated and less-vaccinated elderly people.MethodsA case–crossover design was applied to 1835 elderly ACS patients who were obtained from the 1-million sample of Taiwan National Health Insurance Research Data with inclusion criteria: (1) the first diagnosis of ACS was in cold season and at age 68 or more, (2) had received the free IV program at least once during the period 3 years before the ACS. They were stratified into two groups: 707 had received flu vaccinations for all the 3 years and the remaining 1128 had not. The measurements of air pollutants, temperature, and humidity corresponding to each of the 3 days prior to the ACS diagnosis date were retrieved from the data banks of the Taiwan Environmental Protection Administration and Central Weather Bureau.FindingsIncreases in air pollution concentrations of CO, NO2, PM10 or PM2.5 and decreases in temperature significantly influenced the risk of ACS for the non-continuously vaccinated elderly population; however, less significant effects were observed for the continuously vaccinated population.ConclusionConsecutive influenza vaccination may potentially offer resistance against the detrimental effects of air pollution and changes in temperature in frail elderly adults with ACS. Future studies are needed to directly assess the interaction effect between the vaccination and environmental factors on ACS.  相似文献   
46.
Ticagrelor is a cornerstone of modern antithrombotic therapy alongside aspirin in patients with acute coronary syndrome and after percutaneous coronary intervention. Adverse effects such as bleeding and dyspnea have been associated with premature ticagrelor discontinuation, which may limit any potential advantage of ticagrelor over clopidogrel. The randomized trials of ticagrelor captured adverse events, offering the opportunity to more precisely quantify these effects across studies. Therefore, a meta-analysis of 4 randomized clinical trials of ticagrelor conducted between January 2007 and June 2017 was performed to quantify the incidence and causes of premature ticagrelor discontinuation. Among 66,870 patients followed for a median 18 months, premature ticagrelor discontinuation was seen in 25%; bleeding was the most common cause of discontinuation followed by dyspnea. Versus the comparators, the relative risk of dyspnea-related discontinuation during follow-up was 6.4-fold higher, the relative risk of bleeding was 3.2-fold higher, and the relative risk of discontinuation due to any adverse event was 59% higher for patients receiving ticagrelor. Understanding these potential barriers to adherence to ticagrelor is crucial for informed patient-physician decision making and can inform future efforts to improve ticagrelor adherence. This review discusses the incidence, causes, and biological mechanisms of ticagrelor-related adverse effects and offers strategies to improve adherence to ticagrelor.  相似文献   
47.
Background and aimsCoronary artery disease (CAD) is the principal cause of death in individuals with non-alcoholic fatty liver disease (NAFLD). The aim of this study was to use genetic epidemiology to study the association between de novo lipogenesis (DNL), one of the major pathways leading to NAFLD, and CAD risk.Methods and resultsDNL susceptibility genes were used as instruments and selected using three approaches: 1) genes that are associated with both high serum triglycerides and low sex hormone-binding globulin, both downstream consequences of DNL (unbiased approach), 2) genes that have a known role in DNL (biased approach), and 3) genes that have been associated with serum fatty acids, used as a proxy of DNL. Gene-CAD effect estimates were retrieved from the meta-analysis of CARDIoGRAM and the UK Biobank (~76014 cases and ~264785 controls). Effect estimates were clustered using a fixed-effects meta-analysis. Twenty-two DNL susceptibility genes were identified by the unbiased approach, nine genes by the biased approach and seven genes were associated with plasma fatty acids. Clustering of genes selected in the unbiased and biased approach showed a statistically significant association with CAD (OR:1.016, 95%CI:1.012; 1.020 and OR:1.013, 95%CI:1.007; 1.020, respectively), while clustering of fatty acid genes did not (OR:1.004, 95%CI:0.996–1.011). Subsequent exclusion of potential influential outliers did reveal a statistically significant association (OR:1.009, 95%CI:1.000; 1.018).ConclusionsDNL susceptibility genes are associated with an increased risk of CAD. These findings suggest that DNL may be involved in the pathogenesis of CAD and favor further development of strategies that target NAFLD through DNL.  相似文献   
48.
目的探索当归四逆汤辅助治疗冠状动脉粥样硬化性心脏病(冠心病)的疗效及其作用机制。方法选取2017年3月—2018年3月陕西中医药大学附属医院治疗的冠心病心绞痛患者60例,将患者随机分为对照组和实验组,每组30例。对照组采用常规西药治疗,实验组除了进行常规西药治疗外,同时给予当归四逆汤进行辅助治疗4周。比较2组的临床疗效,治疗前后动态心电图缺血性ST—T改变时间、血脂水平以及心脏功能指标的差异。结果实验组患者的心绞痛症状疗效治疗总有效率为86.7%(26/30),对照组总有效率为70.0%(21/30),实验组总有效率明显高于对照组(P<0.05);治疗后2组缺血性ST—T改变时间均较治疗前明显缩短(P均<0.05),且治疗后实验组患者的缺血性ST-T改变的时间明显短于对照组(P<0.05);治疗后2组的总胆固醇(TC)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)水平相对于本组治疗前明显降低(P均<0.05),高密度脂蛋白胆固醇(HDL-C)水平均比本组治疗前明显升高(P均<0.05),且治疗后实验组患者血清中TC、TG、LDL-C水平明显低于对照组(P均<0.05),HDL-C水平明显高于对照组(P<0.05)。2组治疗后心排血量(CO)、室间隔厚度(IVST)、左室射血分数(LVEF)和左室舒张末期内径(LVEDD)均较治疗前明显改善(P均<0.05),且实验组各指标改善情况明显优于对照组(P<0.05)。结论当归四逆汤辅助治疗冠心病的疗效良好,其机制可能是通过调节血脂代谢,改善血液循环和心脏功能来实现的。  相似文献   
49.
50.
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