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   5336篇
  免费   372篇
  国内免费   21篇
耳鼻咽喉   23篇
儿科学   165篇
妇产科学   131篇
基础医学   825篇
口腔科学   188篇
临床医学   399篇
内科学   1276篇
皮肤病学   223篇
神经病学   573篇
特种医学   85篇
外科学   429篇
综合类   24篇
预防医学   461篇
眼科学   151篇
药学   391篇
中国医学   36篇
肿瘤学   349篇
  2023年   45篇
  2022年   85篇
  2021年   194篇
  2020年   119篇
  2019年   191篇
  2018年   205篇
  2017年   145篇
  2016年   183篇
  2015年   181篇
  2014年   246篇
  2013年   283篇
  2012年   489篇
  2011年   478篇
  2010年   263篇
  2009年   204篇
  2008年   389篇
  2007年   316篇
  2006年   301篇
  2005年   311篇
  2004年   285篇
  2003年   238篇
  2002年   263篇
  2001年   24篇
  2000年   25篇
  1999年   40篇
  1998年   36篇
  1997年   28篇
  1996年   21篇
  1995年   15篇
  1994年   10篇
  1993年   13篇
  1992年   11篇
  1991年   10篇
  1990年   7篇
  1989年   5篇
  1988年   6篇
  1987年   7篇
  1986年   7篇
  1984年   3篇
  1983年   4篇
  1982年   6篇
  1981年   4篇
  1980年   3篇
  1978年   3篇
  1976年   2篇
  1974年   4篇
  1972年   2篇
  1971年   2篇
  1970年   2篇
  1967年   2篇
排序方式: 共有5729条查询结果,搜索用时 359 毫秒
101.
J Clin Hypertens(Greenwich). 2010;12:508–515. © 2010 Wiley Periodicals, Inc. To evaluate the long-term prognostic significance of different ranges of the percentage fall in nighttime blood pressure (BP) of the nondipping pattern, 1200 hypertensive patients (645 women, age 51±12 years) underwent ambulatory BP monitoring under stabilized therapy. The occurrence of cardiovascular (CV) events was followed for 9833 patient-years and analyzed by the Cox hazard model. There were 152 CV fatal/nonfatal events (79 strokes, 51 coronary events, 22 others) during the 15.2 years of follow-up. According to nighttime BP fall (%) the authors noted: <0% (reverse-dippers [RD], n=83); 0%–4.9% (nondippers 1 [ND1], n=207); 5%–9.9% (nondippers 2 [ND2], n=311), 10%–19.9% (dippers [D], n=523); and ≥20% (extreme dippers [ED], n=76). After adjustment for confounding variables, hazard ratios (95% confidence interval) of CV event and stroke in RD vs D were 2.29 (1.31–3.99) and 2.46 (1.11–5.49); of ND1 vs D were 1.42 (1.12–1.79) and 1.62 (1.17–2.23); and of ND1 vs ND2 were 2.24 (1.33–3.75) and 2.30 (1.15–4.58). No differences were found in RD vs ND1 and ND2 vs D. Nondippers have a higher CV risk than dippers but only for a nighttime BP fall <5% suggesting that the limits for nondipping should be redefined for a stratification of CV risk.  相似文献   
102.
103.
104.
PURPOSE OF REVIEW: Respiratory syncytial virus is the leading viral pathogen associated with lower respiratory tract infection in young children worldwide. The pathogenesis of acute bronchiolitis and the mechanisms by which the virus induces long-term airway disease remain to be elucidated. This review highlights new findings reported in the English-language medical literature from January 2004 to January 2005. RECENT FINDINGS: Several studies have confirmed a strong association between respiratory syncytial virus infection in infancy and an increased risk for recurrent wheezing. Evidence indicates that the exaggerated immune response and abnormal neurogenic mechanisms induced by the virus play a significant role in the pathogenesis of the disease. Different genetic and immune markers have been correlated with acute disease severity and with increased risk of long-term pulmonary abnormalities. Recently, the application of real time polymerase chain reaction has demonstrated the persistence of respiratory syncytial virus RNA in the lungs of infected mice for months after inoculation. This unexpected observation has stimulated discussions as to whether the long-term presence of the virus could contribute to the long-term airway disease observed in children after respiratory syncytial virus lower respiratory tract infection. SUMMARY: Despite almost half a century of active research into the pathogenesis of respiratory syncytial virus-induced acute and chronic airway disease, many questions remain unresolved. Studies in animal models demonstrate that interventions reducing viral replication resulted in improvement of acute disease severity and long-term pulmonary abnormalities. The stage is ready for clinical studies to determine whether preventing or delaying the primary infection could reduce the incidence of recurrent wheezing in children.  相似文献   
105.
106.
107.
108.
Primary cystic pancreatic neoplasms are rare tumors, with an approximate prevalence of 10% of cystic pancreatic lesions. Most of these lesions correspond to mucinous cystic neoplasm, serous cystoadenoma and intraductal papillary mucinous tumor (IPMT). IPMT is characterized by diffuse dilatation of the main pancreatic duct and/or side branches with inner defects related to mucin or tumor, or mucin extrusion from a patent ampulla. IPMT has a low potential for malignancy, with a low growth rate, a low rate of metastatic spread and postsurgical recurrence. Over the last few years, major advances have been made in the diagnostic and therapeutic management of this tumor.  相似文献   
109.

Background

The right ventricular ejection fraction (RVEF) is a surrogate marker of right ventricular function in pulmonary hypertension (PH), but its measurement is complicated and time consuming. The tricuspid annular plane systolic excursion (TAPSE) measures only the longitudinal component of RV contraction while the right ventricular fractional area change (RVFAC) takes into account both the longitudinal and the transversal components. The aim of our study was to evaluate the relationship between RVEF, RVFAC, and TAPSE according to hemodynamic severity in two groups of patients with PH: pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH).

Methods and Results

Fifty-four patients with PAH (n?=?15) and CTEPH (n?=?39) underwent right heart catheterization and cardiac magnetic resonance (CMR). The ventricular volumes and areas, TAPSE, and eccentricity index were measured. The RVFAC was more strongly correlated with the RVEF (r?=?0.81, p?<?0.0001) than the TAPSE (r?=?0.63, p?<?0.0001). RVEF?<?35% was better predicted by the RVFAC than the TAPSE (TAPSE: AUC?=?0.77 and RVFAC: AUC?=?0.91; p?=?0.042). In the group with the worse hemodynamic status, the RVFAC correlated much better with the RVEF than the TAPSE. There were no significant differences in the CMR data analyzed between the groups of PAH and CETPH patients.

Conclusions

The RVFAC is a good index to estimate RVEF in PH patients; even better than the TAPSE in patients with more severe hemodynamic profile, possibly for including the transversal component of right ventricular function in its measurement. Furthermore, RVFAC performance was similar in the two PH groups (PAH and CTEPH).
  相似文献   
110.
BACKGROUND: The different diagnosis between hypertrophic cardiomyopathy and athlete's heart has important clinical implications. The assessment of long axis left ventricular function with tissue Doppler imaging in hypertrophic cardiomyopathy (showing systolic and diastolic dysfunction with heterogeneity and asynchrony), may be useful in the differentiation of these situations. AIM: To study, with tissue Doppler imaging, long axis left ventricular function in a population of athletes (rowers) and to compare it with a population of non-obstructive hypertrophic cardiomyopathy patients. METHODS: In 24 patients with non-obstructive hypertrophic cardiomyopathy and in 20 competitive rowers with similar age, blood pressure and heart rate, we analyzed mitral annulus motion with pulsed tissue Doppler imaging in the 4 sides of the annulus (septal, lateral, inferior, anterior), in apical views. In each wave (systolic, rapid filling and atrial contraction) we measured velocities, time intervals and velocity-time integrals, and calculated heterogeneity and asynchrony indices. Data were compared between the groups, between the different sides in each group ("parallel analysis") and with conventional indices of global function. RESULTS: Hypertrophic cardiomyopathy patients showed: systolic function: lower velocities and integrals, shorter ejection time and shorter systolic time. These abnormalities occurred even in annular sites contiguous to walls without hypertrophy. DIASTOLIC FUNCTION: Much lower rapid filling velocities and integrals, lower atrial contraction velocities and integrals, lower e/a, longer isovolumic relaxation time and time to peak rapid filling wave. These abnormalities occurred even in annular sites adjacent to walls without hypertrophy. In the athletes group, the e/a ratio was never < 1, in any annular site. In hypertrophic cardiomyopathy patients this ratio was < 1 in 27% of the sites. CONCLUSIONS: 1--Systolic and diastolic long axis left ventricular function is different in hypertrophic cardiomyopathy and in athletes, in all mitral annulus sides. 2--The presence of these abnormalities in annular sites contiguous to walls without hypertrophy suggests that this technique may be useful in the differential diagnosis between these groups, particularly in the "gray zone" of Maron.  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