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   1588篇
  免费   69篇
  国内免费   4篇
耳鼻咽喉   7篇
儿科学   80篇
妇产科学   5篇
基础医学   297篇
口腔科学   16篇
临床医学   94篇
内科学   352篇
皮肤病学   16篇
神经病学   95篇
特种医学   35篇
外科学   421篇
综合类   2篇
预防医学   40篇
眼科学   12篇
药学   105篇
中国医学   1篇
肿瘤学   83篇
  2023年   8篇
  2022年   16篇
  2021年   28篇
  2019年   32篇
  2018年   24篇
  2017年   15篇
  2016年   21篇
  2015年   27篇
  2014年   28篇
  2013年   37篇
  2012年   62篇
  2011年   61篇
  2010年   45篇
  2009年   39篇
  2008年   61篇
  2007年   69篇
  2006年   65篇
  2005年   66篇
  2004年   62篇
  2003年   59篇
  2002年   85篇
  2001年   70篇
  2000年   58篇
  1999年   49篇
  1998年   27篇
  1996年   12篇
  1995年   9篇
  1994年   15篇
  1993年   16篇
  1992年   41篇
  1991年   50篇
  1990年   45篇
  1989年   57篇
  1988年   40篇
  1987年   51篇
  1986年   36篇
  1985年   34篇
  1984年   20篇
  1983年   7篇
  1981年   5篇
  1979年   14篇
  1978年   8篇
  1977年   9篇
  1976年   9篇
  1974年   8篇
  1973年   5篇
  1971年   7篇
  1968年   6篇
  1967年   5篇
  1966年   5篇
排序方式: 共有1661条查询结果,搜索用时 31 毫秒
61.
An association between ambient air pollution and reduced cardiac autonomic function assessed by heart rate variability (HRV) mainly in elderly persons has been suggested by a number of epidemiological studies, but the link between the HRV and pulmonary function in humans remains unknown although such air pollution should primarily affect pulmonary function. To clarify this link, pulmonary ventilation parameters such as oxygen uptake (V(O(2))) and carbon dioxide output (V(CO(2))), as well as the HRV with spectral analysis (high- and low-frequency components of HRV, i.e., CCV(HF) and CCV(LF), reflecting cardiac parasympathetic and sympathetic activities, respectively), were measured in 66 healthy women aged 19-20 years after an overnight fast of 12 h. Significant correlations were found between the CCV(HF) of HRV and both the end-tidal carbon dioxide concentration (FET(CO(2))) and gas exchange ratio (V(CO(2))/V(O(2))) in the subjects (partial correlation coefficients r = 0.354 and 0.320, respectively), whereas there was no significant connection between the FET(CO(2)) and the V(CO(2))/V(O(2)). Similarly, the CCV(LF) correlated significantly with the resting tidal volume of lung (r = 0.364). These findings suggest that resting pulmonary ventilation function interacts with cardiac autonomic function assessed by the HRV, at least in healthy young adults, which may be useful for explaining the pathophysiology concerning the short-term effect of air pollution such as fine particulate matter on cardiovascular function.  相似文献   
62.
BackgroundFew studies have investigated right atrial (RA) remodeling in heart failure (HF) with preserved ejection fraction (HFpEF). This study sought to characterize the RA remodeling in HFpEF and to determine its prognostic significance.Methods and ResultsPatients with HFpEF were classified based on the presence of RA enlargement (RA volume index >39 mL/m2 in men and >33 mL/m2 in women). Compared with patients with normal RA size (n = 234), patients with RA dilation (n = 67) showed a higher prevalence of atrial fibrillation (AF), worse right ventricular systolic function, more severe pulmonary hypertension, and a greater prevalence of mild tricuspid regurgitation, as well as impaired RA reservoir function, with increased hepatobiliary enzyme levels. AF was strongly associated with the presence of RA dilation (odds ratio [OR] 10.2, 95% confidence interval [CI] 4.00–26.1 in current AF vs no AF and odds ratio 3.38, 95% CI 1.26–9.07, earlier AF vs no AF). Patients with RA dilation had more than a two-fold increased risk of composite outcomes of all-cause mortality or HF hospitalization (adjusted hazard ratio 2.01, 95% CI 1.09–3.70, P = .02). The presence of RA dilation also displayed an additive prognostic value over left atrial dilation alone.ConclusionsThese data demonstrate that HFpEF with RA remodeling is associated with distinct echocardiographic features characterizing advanced right heart dysfunction with an increased risk of adverse outcomes.  相似文献   
63.
Kozu  Yutaka  Kurosawa  Yusuke  Yamada  Shiho  Fukuda  Asami  Hikichi  Mari  Hiranuma  Hisato  Akahoshi  Toshiki  Gon  Yasuhiro 《Sleep & breathing》2021,25(2):767-776
Sleep and Breathing - To investigate the different pathophysiologies of obstructive sleep apnea (OSA) phenotypes using cluster analysis. Differences between leptin/adiponectin levels in the...  相似文献   
64.
Resuscitation was possible in a case of fulminant myocarditis with refractory ventricular fibrillation (Vf) using a percutaneous cardiopulmonary support system (PCPS). A 46-year old Japanese man suddenly experienced cardiopulmonary dysfunction shortly after the onset of flu symptoms, was promptly diagnosed as having fulminant myocarditis and PCPS was immediately initiated. On the second day in the hospital, refractory Vf occurred, which lasted for approximately 2h despite repeated efforts to terminate it. Finally, a large dose of steroids was administered. From the third day of hospitalization and onwards, the Vf disappeared totally. The patient completely recovered from such a serious state in 6 months. During the following 3 years, he has had no clinical symptoms of worsening. As in this case demonstrates, most myocarditis is curable and invasive measures are very helpful in rescuing patients from the fulminant type with refractory Vf.  相似文献   
65.
A youth of 16 years of age died suddenly and quite unexpectedly while walking to school. The necropsy disclosed a quadricuspid aortic valve with complete isolation of the left coronary artery by an adherent aortic valve cusp. The left ventricular myocardium showed subendocardial contraction band necrosis suggesting that critical ischaemia had triggered a state of hypercontraction, in keeping with ventricular fibrillation as the immediate cause of death. The site of the anomaly in the aortic root showed dysplasia of the aortic wall and the affected valve cusp, histologically similar to the changes that characterise supravalvar aortic stenosis. The findings suggest a developmental anomaly, possibly a forme fruste of supravalvar aortic stenosis, rather than a postnatally acquired condition.  相似文献   
66.
ObjectiveComputer-aided design and computer-aided manufacturing (CAD/CAM) techniques are increasingly applied to mandibular reconstruction, but the superiority of this method in oral food intake has not been well established. Considering the extent of mandibular defects, this retrospective study was aimed to clarify the impact of CAD/CAM mandibular reconstruction on chewing and swallowing function after surgery for locally advanced oral cancer.Materials and methodsWe performed a retrospective review of 50 patients who had undergone segmental mandibulectomy with free flap reconstruction for locally advanced oral cancer. The patients’ Functional Oral Intake Scale scores were measured at 3 months after surgery, and possible contributing factors including CAD/CAM mandibular reconstruction and the extent of mandibular defects for oral food intake were subjected to univariate analysis and multivariate logistic regression analysis.ResultsMultivariate logistic regression analysis showed that CAD/CAM mandibular reconstruction was independently associated with good oral intake, whereas both anterior or extensive mandibular resection and glossectomy were also independently associated with poor oral intake after surgery.ConclusionThe present study showed the positive impact of CAD/CAM mandibular reconstruction on chewing and swallowing function after surgery for locally advanced oral cancer for the first time.  相似文献   
67.
68.
The appropriate indication for, management of and limitations to extracorporeal life support (ECLS) and the timing of a switch to a ventricular assist device (VAD) remain controversial issues in patients with acute myocardial infarction (AMI) complicated with cardiogenic shock or cardiopulmonary arrest. To evaluate and discuss these issues, we studied patients with AMI treated with ECLS and compared deceased and discharged patients. Thirty-eight patients with AMI who needed ECLS [35 men (92.1 %), aged 59.9 ± 13.5 years] were enrolled in this study. Of these 38 patients, 34 subsequently underwent percutaneous coronary intervention (PCI), and four subsequently received coronary artery bypass grafting (CABG). Fourteen patients (36.8 %) were discharged from the hospital. The outcome was not favorable for those patients with deteriorating low output syndrome (LOS) and the development of leg ischemia, hemolysis and multiple organ failure during ECLS. Levels of creatine kinase, creatine kinase-MB (CK-MB), lactate dehydrogenase, serum creatinine (Cr) and amylase after the patient had been put on ECLS and fluctuation of the cardiac index, blood pressure, arterial blood gas analysis and CK-MB and Cr levels during ECLS were indicators to switch from the ECLS to VAD. In the case of patients with no complication associated with ECLS, 4.6–5.6 days after initiation of ECLS was assumed to be the threshold to decide whether to switch from ECLS to VAD. Patients with AMI who suddenly developed refractory pulseless ventricular tachycardia or ventricular fibrillation without deteriorating LOS and who underwent successful PCI or CABG, and who prevented the complications associated with ECLS, showed a high probability of recovering with ECLS.  相似文献   
69.
70.
In Japan, public funding for HPV vaccination began in 2010 for girls aged 13–16 years (birth cohort years 1994–1997) and women born in 1994 who turned 25 in 2019. We aimed to verify the long‐term effectiveness of the bivalent HPV vaccine in women aged 25 years. Subjects were women aged 25–26 years who underwent cervical cancer screening and HPV testing in Niigata from 2019 to 2020 (birth cohort years 1993–1994). Information on vaccination status and sexual behavior was obtained from a questionnaire and municipal records. We compared the HPV infection rates of the vaccinated and unvaccinated groups. Of the 429 registrants, 150 (35.0%) and 279 (65.0%) were vaccinated and unvaccinated, respectively. The average period from HPV vaccination to HPV testing was 102.7 months (8.6 years), with a median of 103 months (range 92–109 months). The HPV high‐risk infection rate was 21.3% (32/150) in the vaccinated group and 23.7% (66/279) in the unvaccinated group (P = 0.63). The HPV16/18 infection rate was 0% (0/150) in the vaccinated group and 5.4% (15/279) in the unvaccinated group, showing a significant difference (P = 0.0018), and the vaccine effectiveness was 100%. The cross‐protective type HPV31/45/52 infection rate in the vaccinated group was significantly lower than that in the unvaccinated group (3.3% vs. 10.0%, P = 0.013). There was no significant difference in the mean age at sexual debut and the number of previous sexual partners between the two groups. We have demonstrated the long‐term 9‐year effectiveness of the bivalent vaccine against HPV infection for the first time in Japan.  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