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   1947篇
  免费   88篇
  国内免费   4篇
耳鼻咽喉   13篇
儿科学   74篇
妇产科学   22篇
基础医学   144篇
口腔科学   24篇
临床医学   156篇
内科学   444篇
皮肤病学   12篇
神经病学   218篇
特种医学   66篇
外科学   270篇
综合类   31篇
一般理论   2篇
预防医学   79篇
眼科学   65篇
药学   134篇
中国医学   3篇
肿瘤学   282篇
  2023年   27篇
  2022年   53篇
  2021年   94篇
  2020年   42篇
  2019年   66篇
  2018年   83篇
  2017年   40篇
  2016年   48篇
  2015年   49篇
  2014年   76篇
  2013年   103篇
  2012年   167篇
  2011年   155篇
  2010年   72篇
  2009年   59篇
  2008年   98篇
  2007年   105篇
  2006年   86篇
  2005年   84篇
  2004年   99篇
  2003年   88篇
  2002年   68篇
  2001年   20篇
  2000年   26篇
  1999年   34篇
  1998年   10篇
  1997年   8篇
  1996年   9篇
  1995年   9篇
  1994年   13篇
  1993年   6篇
  1992年   12篇
  1991年   14篇
  1990年   8篇
  1989年   7篇
  1988年   14篇
  1987年   15篇
  1986年   15篇
  1985年   12篇
  1984年   12篇
  1983年   4篇
  1982年   4篇
  1981年   3篇
  1980年   2篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1975年   5篇
  1973年   2篇
  1968年   1篇
排序方式: 共有2039条查询结果,搜索用时 0 毫秒
31.
32.
IntroductionThere is limited literature on coronavirus disease 2019 (COVID -19) complications such as thromboembolism, cardiac complications etc. as possible trigger for stroke. Hence, we aim to evaluate the prevalence and outcomes of COVID-19 related cardiovascular complications and secondary infection and their possibility as potential triggers for the stroke.MethodsData from observational studies describing the complications [acute cardiac injury (ACI), cardiac arrhythmias (CA), disseminated intravascular coagulation (DIC), septic shock, secondary infection] and outcomes of COVID‐19 hospitalized patients from December 1, 2019 to June 30, 2020, were extracted following PRISMA guidelines. Adverse outcomes defined as intensive care units, oxygen saturation less than 90%, invasive mechanical ventilation, severe disease, and in‐hospital mortality. The odds ratio and 95% confidence interval were obtained, and forest plots were created using random‐effects models. A short review of these complications as triggers of stroke was conducted.Results16 studies with 3480 confirmed COVID-19 patients, prevalence of ACI [38%vs5.9%], CA [26%vs5.3%], DIC [4%vs0.74%], septic shock [18%vs0.36%], and infection [30%vs12.5%] was higher among patients with poor outcomes. In meta-analysis, ACI [aOR:9.93(95%CI:3.95–25.00], CA [7.52(3.29–17.18)], DIC [7.36(1.24–43.73)], septic shock [30.12(7.56–120.10)], and infection [10.41(4.47–24.27)] had higher odds of adverse outcomes. Patients hospitalized with acute ischemic stroke and intracerebral hemorrhage, had complications like pulmonary embolism, venous thromboembolism, DIC, etc. and had poor outcomesConclusionThe complications like acute cardiac injury, cardiac arrhythmias, DIC, septic shock, and secondary infection had poor outcomes. Patients with stroke were having history of these complications. Long term monitoring is required in such patients to prevent stroke and mitigate adverse outcomes.  相似文献   
33.
Hemorrhagic complications are uncommon after percutaneous transhepatic biliary drainage. The presenting features include bleeding through or around the drainage catheter, hematemesis or melena. Diagnosis requires cholangiography, CT angiography or conventional angiography. Minor venous hemorrhage is managed by catheter repositioning, clamping or upgrading to a larger bore catheter. Major vascular injuries require percutaneous or endovascular procedures like embolization or stenting. A complete knowledge of these complications will direct the interventional radiologist to take adequate precautions to reduce their incidence and necessary steps in their management. This review presents and discusses various hemorrhagic complications occurring after percutaneous transhepatic biliary drainage along with their treatment options and suggests a detailed algorithm.  相似文献   
34.
Surface‐functionalized multiwall carbon nanotubes (MWCNTs) are incorporated in poly(methyl methacrylate)/styrene acrylonitrile (PMMA/SAN) blends and the pretransitional regime is monitored in situ by melt rheology and dielectric spectroscopy. As the blends exhibit weak dynamic asymmetry, the obvious transitions in the melt rheology due to thermal concentration fluctuations are weak. This is further supported by the weak temperature dependence of the correlation length (ξ ≈ 10–12 Å) in the vicinity of demixing. Hence, various rheological techniques in both the temperature and frequency domains are adopted to evaluate the demixing temperature. The spinodal decomposition temperature is manifested in an increase in the miscibility gap in the presence of MWCNTs. Furthermore, MWCNTs lead to a significant slowdown of the segmental dynamics in the blends. Thermally induced phase separation in the PMMA/SAN blends lead to selective localization of MWCNTs in the PMMA phase. This further manifests itself in a significant increase in the melt conductivity.

  相似文献   

35.
Role of the coronary sinus in maintenance of atrial fibrillation   总被引:2,自引:0,他引:2  
INTRODUCTION: Bursts of tachycardia arising in the pulmonary veins may play an important role in perpetuating atrial fibrillation (AF). However, the role of the coronary sinus (CS) in the perpetuation of AF has been unclear. The aim of this study was to determine whether the CS plays a role in perpetuation of AF. METHODS AND RESULTS: Pulmonary vein isolation was performed by segmental ostial ablation with radiofrequency energy in 22 consecutive patients with paroxysmal AF. Bipolar and unipolar electrograms recorded in the left atrium and CS were analyzed during atrial pacing from the mitral annulus and during AF. There was a mean of 2.5 +/- 0.5 electrical connections between the CS and the left atrium. The electrical connections between the left atrium and CS were ablated with a mean of 6.2 +/- 2.7 minutes of radiofrequency energy applied along the atrial side of the inferior mitral annulus. During AF, episodes of intermittent tachycardia alternated between the left atrium and the CS. Among the 22 patients, sustained AF was still inducible in 9 after pulmonary vein isolation. After electrical disconnection of the CS from the left atrium, sustained AF was inducible in only 3 of these 9 patients. CONCLUSION: The CS may be a source of rapid repetitive electrical activity during AF. The lower probability of inducible sustained AF after electrical disconnection of the CS from the left atrium suggests that the CS may play a role in perpetuating AF.  相似文献   
36.
37.
BackgroundThe association of depression and epilepsy is thought to be bidirectional. The present study aimed to evaluate the prevalence of depression in patients on antiepileptic drugs (AEDs) and factors affecting it.MethodsIn this preliminary cross sectional study, patients at epilepsy clinic of a tertiary care centre were studied for occurrence of depression, using Hospital Anxiety and Depression Scale (HADS-D) and Patient Health Questionnaire (PHQ-2) scales. Correlation analysis was carried out to determine the factors associated with presence of depression in these patients.ResultsA total of 12 AEDs (maximum 5 per patient including older and newer) were prescribed to 933 patients in different treatment regimens over a period of 3 years. The median age of the patients was 22 years (10–77) and among them 63.5% were men. Mild and clinically relevant depression occurred in 279 (29.9%) and 223 (23.9%) patients, respectively. Mean HADS-D and PHQ-2 score was significantly higher with polytherapy as compared to monotherapy (p < 0.001). Patients on levetiracetam exhibited significantly higher HADS-D score in comparison to phenytoin (p < 0.001), carbamazepine (p < 0.001) and sodium valproate (p < 0.05). However, there was no significant difference in PHQ score among patients on monotherapy of different AEDs. Multivariate regression analysis suggested correlation between depression and seizure frequency, total number of AEDs and their load (p < 0.001).ConclusionDepressive symptoms were found to be present in more than half of the patients with epilepsy which require detailed work up for depression. Levetiracetam was found to be associated with a higher incidence of subclinical depression which needs further investigation.  相似文献   
38.
39.
40.
Ablation and Progression of Atrial Fibrillation. Objective: The objective was to determine the effect of radiofrequency catheter ablation (RFA) on progression of paroxysmal atrial fibrillation (AF). Background: Progression to persistent AF may occur in up to 50% of patients with paroxysmal AF receiving pharmacological therapy. Hypertension, age, prior transient ischemic event, chronic obstructive pulmonary disease, and heart failure (HATCH score) have been identified as independent risk factors for progression of AF. Methods: RFA was performed in 504 patients (mean age: 58 ± 10 years) to eliminate paroxysmal AF. A repeat RFA procedure was performed in 193 patients (38%). Clinical variables predictive of outcome and their relation to progression of AF after RFA were assessed using multivariate analysis. Results: At a mean follow‐up of 27 ± 12 months after RFA, 434/504 patients (86%) were in sinus rhythm; 49/504 patients (9.5%) continued to have paroxysmal AF; and 14 (3%) were in atrial flutter. Among the 504 patients, 7 (1.5%) progressed to persistent AF. In patients with recurrent AF after RFA, paroxysmal AF progressed to persistent AF in 7/56 (13%, P < 0.001). The progression rate of AF was 0.6% per year after RFA (P < 0.001 compared to 9% per year reported in pharmacologically treated patients). Age >75 years, duration of AF >10 years and diabetes were independent predictors of progression to persistent AF. The HATCH score was not significantly different between patients with paroxysmal AF who did and did not progress to persistent AF (0.7 ± 0.8 vs 1.0 ± 0.5, P = 0.3). Conclusions: Compared to a historical control group of pharmacologically treated patients with paroxysmal AF, RFA appears to reduce the rate of progression of paroxysmal AF to persistent AF. Age, duration of AF, and diabetes are independent risk factors for progression to persistent AF after RFA. (J Cardiovasc Electrophysiol, Vol. 23, pp. 9‐14, January 2012)  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