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   4046篇
  免费   206篇
  国内免费   13篇
耳鼻咽喉   86篇
儿科学   113篇
妇产科学   37篇
基础医学   557篇
口腔科学   223篇
临床医学   351篇
内科学   680篇
皮肤病学   76篇
神经病学   406篇
特种医学   172篇
外科学   578篇
综合类   10篇
一般理论   1篇
预防医学   333篇
眼科学   123篇
药学   242篇
中国医学   4篇
肿瘤学   273篇
  2024年   4篇
  2023年   34篇
  2022年   55篇
  2021年   106篇
  2020年   77篇
  2019年   90篇
  2018年   108篇
  2017年   60篇
  2016年   123篇
  2015年   105篇
  2014年   138篇
  2013年   205篇
  2012年   274篇
  2011年   264篇
  2010年   158篇
  2009年   146篇
  2008年   300篇
  2007年   278篇
  2006年   306篇
  2005年   249篇
  2004年   226篇
  2003年   232篇
  2002年   210篇
  2001年   37篇
  2000年   23篇
  1999年   33篇
  1998年   53篇
  1997年   33篇
  1996年   30篇
  1995年   30篇
  1994年   34篇
  1993年   35篇
  1992年   21篇
  1991年   13篇
  1990年   10篇
  1989年   13篇
  1988年   17篇
  1987年   9篇
  1986年   9篇
  1985年   13篇
  1984年   13篇
  1983年   14篇
  1982年   10篇
  1981年   10篇
  1980年   8篇
  1979年   12篇
  1978年   12篇
  1977年   4篇
  1975年   4篇
  1974年   4篇
排序方式: 共有4265条查询结果,搜索用时 15 毫秒
91.
92.
Abstract Background: We studied the associations of clustering of metabolic risk factors with plasma levels of alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT) in healthy prepubertal children. Methods: The subjects were a representative population sample of 492 children 6-8 years of age. We assessed body fat percentage (dual-energy X-ray absorptiometry), body mass index, waist circumference, systolic and diastolic blood pressure, glucose, insulin, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, ALT, GGT, and high-sensitivity C-reactive protein (hsCRP) and calculated a continuous metabolic syndrome score variable. We also used factor analysis to examine whether high-normal liver enzymes are a feature of metabolic syndrome among children. Results: Children with overweight or obesity, defined by International Obesity Task Force (IOTF) criteria, had a 2.1-times higher risk of having ALT and a 4.5-times higher risk of having GGT in the highest fifth of its distribution than normal weight children. Children in the highest sex-specific third of metabolic syndrome score, body fat percentage, waist circumference, and insulin had a two to three times higher risk of being in the highest fifth of ALT and GGT. Moreover, children in the highest third of glucose and hsCRP had a 2.5-fold risk of being in the highest fifth of GGT. First-order factor analysis yielded three factors; the first included insulin, glucose, and triglycerides; the second waist circumference, insulin, GGT, and hsCRP; and the third HDL-C, triglycerides, waist circumference, and insulin. Second-order factor analysis yielded a single metabolic syndrome factor, explaining 64.1% of the variance. Conclusions: Clustering of metabolic risk factors, particularly excess body fat, is associated with high-normal levels of ALT and GGT in prepubertal children. High-normal levels of liver enzymes, especially GGT, and systemic low-grade inflammation could be considered features of metabolic syndrome among children. Subtle changes in liver function may play an important role in the pathogenesis of metabolic syndrome beginning in childhood.  相似文献   
93.
Abstract

Objectives. The inverse and independent association between cardiorespiratory fitness (CRF) and arterial thrombotic disease is well established. However, the potential association between CRF and venous thromboembolism (VTE) is not well known. We aimed to assess the prospective association of CRF with the risk of VTE. Design. Cardiorespiratory fitness, as measured by maximal oxygen uptake (VO2max), was assessed using a respiratory gas exchange analyser in 2,249 men aged 42–61 years without a history of VTE at baseline in the Kuopio Ischemic Heart Disease prospective cohort. Cox-regression models were used to calculate hazard ratios (HR) with 95% confidence interval (CI) for VTE. We corrected for within-person variability in CRF levels using data from repeat measurements taken several years apart. Results. There were 144 (6.4%) incident VTE events recorded during a median follow-up of 25.2 years. The age-adjusted regression dilution ratio of CRF was 0.58 (95% CI: 0.53–0.64). The risk of VTE did not significantly decrease per 1 standard deviation increase in CRF in age-adjusted analysis (HR 0.90; 95% CI 0.75–1.08). The association remained consistent in analyses adjusted for several established and emerging risk factors (HR 0.90; 95% CI 0.73–1.12). The corresponding adjusted HRs were 0.80 (95% CI: 0.52–1.23) and 0.82 (95% CI: 0.51–1.32) respectively, when comparing the extreme tertiles of CRF levels. Conclusions. In a middle-aged Caucasian male population, CRF was not associated with future risk of VTE. Further studies are required to confirm and to generalize these findings, particulary in women and other age groups.  相似文献   
94.
95.
Healing of tracheal anastomosis after en bloc double-lung or heart-lung transplantation was analysed with the aid of endoscopic laser Doppler flowmetry in 7 patients (group I) with successful bronchial artery revascularization (BAR) and in 5 patients (group II) without or with failed BAR. Fifteen patients undergoing coronary surgery served as a control group. Airway anastomotic index (AAI) was used to express the ratio of Doppler flowmetry values between donor and recipient airway. On postoperative day 1 the mean (range) AAI was 1.3 (1.1-1.6) in group I, 0.74 (0.25-1.0) in group II and 0.95 (0.7-1.4) in the controls.The difference was statistically significant between groups I and II (p = 0.01) and also between group I and the control group (p = 0.003). Two group II patients had low AAI (<0.5), and both developed airway anastomotic complications. We conclude that successful BAR increases blood flow in the airway anastomotic region, and that low AAI on the first postoperative day is a strong predictor of late airway anastomotic complications.  相似文献   
96.
In this report we present our experience of non-invasive magnetic resonance imaging (MR) angiography and selective catheter angiography in assessing the patency of bronchial artery revascularization grafts after an en bloc double-lung and heart-lung transplantation. We studied 8 patients who had undergone pulmonary transplantation with direct bronchial artery revascularization. Catheter angiography was performed 10 days to 63 months postoperatively. MR angiography was performed within 24 h of the catheter procedure and the results were compared with the findings from catheter angiography. Catheter angiography showed the bronchial revascularization graft to be patent in 6 patients and occluded in 2. At MR angiography, the patency of bronchial artery revascularization grafts was reliably identified in 7 of the 8 patients. One patient had inadequate image quality because of void artefacts caused by haemostatic clips. It is concluded that MR angiography is a reliable method for assessing the patency of bronchial artery revascularization grafts.  相似文献   
97.
The study aimed to clarify the role of direct bronchial artery revascularization (BAR) after en bloc double-lung (DLT) and heart-lung transplantation (HLT). Group I comprised eight patients with en bloc DLT or HLT and successful BAR, while group II included 14 DLT or HLT cases without BAR or with failed BAR. From these groups, 2 subgroups were extracted: group III, including 6 cases of en bloc DLT with successful BAR and group IV 10 HLT cases without or with failed BAR. Airway healing was evaluated at bronchoscopy and patency of BAR with angiography. Pulmonary viral, bacterial and fungal infections, rejections and bronchiolitis obliterans syndrome (BOS) were registered. Tracheal healing at 2 weeks and 3 months was better in group I than in group II (p = 0.003 and p = 0.05, respectively). Compared with group IV, tracheal anastomotic healing at 2 weeks was better in group III (p = 0.007) and tended to be better also after 3 months (p = 0.07). The incidence of infections, rejection or BOS did not differ between groups I and II. BAR thus improved healing of tracheal anastomosis.  相似文献   
98.
Background and purpose High age is associated with increased postoperative mortality, but the factors that predict mortality in older hip and knee replacement recipients are not known.

Methods Preoperative clinical and operative data on 1,998 primary total hip and knee replacements performed for osteoarthritis in patients aged ≥ 75 years in a single institution were collected from a joint replacement database and compoared with mortality data. Average follow-up was 4.2 (2.2–7.6) years for the patients who survived. Factors associated with mortality were analyzed using Cox regression analysis, with adjustment for age, sex, operated joint, laterality, and anesthesiological risk score.

Results Mortality was 0.15% at 30 days, 0.35% at 90 days, 1.60% at 1 year, 7.6% at 3 years, and 16% at 5 years, and was similar following hip and knee replacement. Higher age, male sex, American Society of Anesthesiologists risk score of > 2, use of walking aids, preoperative walking restriction (inability to walk or ability to walk indoors only, compared to ability to walk > 1 km), poor clinical condition preoperatively (based on clinical hip and knee scores or clinical severity of osteoarthritis), preoperative anemia, severe renal insufficiency, and use of blood transfusions were associated with higher mortality. High body mass index had a protective effect in patients after hip replacement.

Interpretation Postoperative mortality is low in healthy old joint replacement recipients. Comorbidities and functional limitations preoperatively are associated with higher mortality and warrant careful consideration before proceeding with joint replacement surgery.  相似文献   
99.
100.
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