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   2479篇
  免费   138篇
  国内免费   15篇
耳鼻咽喉   64篇
儿科学   156篇
妇产科学   145篇
基础医学   198篇
口腔科学   56篇
临床医学   196篇
内科学   686篇
皮肤病学   57篇
神经病学   166篇
特种医学   119篇
外科学   435篇
综合类   27篇
一般理论   1篇
预防医学   61篇
眼科学   74篇
药学   105篇
中国医学   3篇
肿瘤学   83篇
  2024年   2篇
  2023年   30篇
  2022年   38篇
  2021年   79篇
  2020年   63篇
  2019年   67篇
  2018年   82篇
  2017年   68篇
  2016年   115篇
  2015年   122篇
  2014年   138篇
  2013年   146篇
  2012年   187篇
  2011年   135篇
  2010年   108篇
  2009年   99篇
  2008年   146篇
  2007年   192篇
  2006年   163篇
  2005年   159篇
  2004年   130篇
  2003年   109篇
  2002年   86篇
  2001年   51篇
  2000年   42篇
  1999年   38篇
  1998年   7篇
  1997年   4篇
  1996年   6篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1969年   1篇
排序方式: 共有2632条查询结果,搜索用时 593 毫秒
51.
Spinal cord injury (SCI) induced oxidative stress affects multiple organ systems including the kidney. We studied the possible protective effects of melatonin on SCI-induced oxidative damage in renal tissues of rats. Wistar albino rats (n = 24) were exposed to SCI and divided into vehicle- or melatonin-treated SCI groups. Melatonin was administred intraperitoneally at a dose of 10 mg/kg for seven days. Renal tissues were investigated by light and electron microscopy. Furthermore, tissue malondialdehyde (MDA) and glutathione (GSH) levels and myeloperoxidase (MPO) and superoxide dismutase (SOD) activities were also determined. In the vehicle-treated SCI group, the renal histology was disturbed compared to controls, whereas the melatonin-treated SCI group showed significantly reduced degeneration of renal tissue as seen by both light and electron microscopy. MDA levels, MPO and SOD activities were increased and GSH levels were decreased in the vehicle-treated SCI group compared to controls. On the other hand, decreased MDA levels and MPO activities and increased GSH levels were observed in the melatonin-treated SCI group compared to vehicle-treated SCI group. These results showed that experimentally induced SCI caused oxidative stress in the rat kidney, whereas melatonin treatment reduced oxidative stress, suggesting that it may be used as a complementary therapy of renal problems occurring following SCI.  相似文献   
52.
Systemic sclerosis (SSc) is a disease characterized by skin and internal organ involvement. There is progressive accumulation of extracellular matrix components in the skin and involved organs. Tissue fibrosis is the prominent reason for mortality, and still, there is no satisfactory treatment. The aim of this study was to evaluate the effects of urotensin-II (U-II) antagonist palosuran in an animal model of scleroderma. We also planned to measure U-II, endothelin-1 (ET-1), and transforming growth factor-β1 (TGF-β1) levels, as well as the association of these levels with dermal thickness. Twenty-four male mice were included in this study and they were divided into three groups—group 1: control group, group 2: fibrosis group, and group 3: fibrosis + palosuran treatment group. Fibrosis + palosuran treatment in group 3 reduced ET-1, U-II, and TGF-β1 levels. In total, the diminished values were statistically significant in the ET-1 and TGF-β1 levels (p?<?0.05). Dermal thickness was higher in the fibrosis group, when compared with the other groups. There was no significant relationship between dermal thickness and ET-1, U-II, or TGF-β1 levels (p?>?0.05). It is believed that U-II is an important mediator in SSc, and its antagonism with palosuran could be a new treatment choice in SSc.  相似文献   
53.
Pulmonary arterial hypertension (PAH) is a progressive and a life-threatening disease with its high morbidity and mortality ratios. On searching for new shining targets in pathogenesis, we noticed, in our previous studies, urotensin-II (UII) in systemic sclerosis with potent angiogenic and pro-fibrotic features. Owing to the mimicking properties of UII with endothelin-1 (ET1), we attempted to investigate the effect of palosuran in a PAH rat model. Thirty rats were randomly divided into three groups, with each group comprising 10 rats: group 1 (control group) received the vehicle subcutaneously, instead of monocrotaline (MCT) and vehicle; group 2 (MCT group) received subcutaneous MCT and vehicle; and group 3 (MCT + palosuran group) received subcutaneous MCT and palosuran. Serum UII, ET1, transforming growth factor-β1 (TGF-β1) levels, pulmonary arteriolar pathology of different diameter vessels, and cardiac indices were evaluated. The ET1, TGF-β1, and UII levels were significantly diminished in the treatment group, similar to the controls (p?<?0.001). Right ventricular hypertrophy index and mean pulmonary arterial pressure scores were also significantly reduced in the treatment group (p?=?0.001). Finally, in the 50–125-μm diameter arterioles, in contrast to Groups 3 and 1, there was a statistically significant thickness (p?<?0.01) in the arteriolar walls of rats in Group 2. The treatment effect on arteries of more than 125-μm diameters was found to be valuable but not significant. Owing to its healing effect on hemodynamic, histological, and biochemical parameters of MCT-induced PAH, palosuran as an antagonist of UII might be an optional treatment alternative for PAH.  相似文献   
54.
55.
56.

Objective

Oxidative metabolism is impaired in several medical conditions including psychiatric disorders, and this imbalance may be involved in the etiology of these diseases. The present study evaluated oxidative balance in pediatric and adolescent patients with attention deficit hyperactivity disorder (ADHD).

Methods

The study included 48 children and adolescents (34 male, 14 female) with ADHD who had no neurological, systemic, or comorbid psychiatric disorders, with the exception of oppositional defiant disorder (ODD), and 24 sex- and age-matched healthy controls (17 male and seven female).

Results

TAS was significantly lower, and TOS and OSI were significantly higher in patients with ADHD than in healthy controls. Total antioxidant levels were lower in patients with comorbid ODD than in those with no comorbidity. No difference was found in TOS or OSI among the ADHD subtypes; however, TAS was higher in the attention-deficient subtype.

Conclusion

Our findings demonstrated that oxidative balance is impaired and oxidative stress is increased in children and adolescents with ADHD. This results are consistent with those of previous studies.  相似文献   
57.
58.

Objectives:

To determine the effect of thrombectomy on platelet function in patients undergoing primary percutaneous coronary intervention (PPCI) for ST segment elevation myocardial infarction (STEMI).

Methods:

This retrospective study included 413 consecutive STEMI patients who underwent PPCI between March 2012 and September 2013 at Kartal Kosuyolu High Specialty Education and Research Hospital, Istanbul, Turkey that were assigned to the thrombus aspiration (TA) group or the non-TA group. Platelet count and mean platelet volume (MPV) were obtained at baseline and 24 hours (h), 48 h, and 72 h post PPCI.

Results:

Baseline MPV was similar in both groups, whereas the baseline platelet count was higher in the TA group (p=0.42 and p=0.002). The platelet count was higher in the TA group 24 h post PPCI (p=0.02), but was similar in both groups 48 h and 72 h post PPCI (p=0.18 and p=0.07). The MPV 48 h and 72 h post PPCI was higher in the non-TA group than in the TA group (8.4 ± 1.3 fL versus 8.7 ± 1.6 fL [p=0.04] and 8.5 ± 1.1 fL versus 8.9 ± 1.5 fL [p=0.04]).

Conclusion:

Thrombectomy reduced platelet activity via removal of thrombi from the coronary arteries in patients undergoing PPCI for STEMI.In acute ST-segment elevation myocardial infarction (STEMI), the main initiating factor is atherosclerotic plaque rupture or erosion, then platelets become activated and aggregated leading to acute coronary artery occlusion.1 Primary percutaneous coronary intervention (PPCI) is the standard treatment in patients with STEMI.2 In recent years, implementation of adjunctive mechanical and pharmacological therapies during PPCI, including manual thrombus aspiration (TA), has improved myocardial reperfusion and clinical outcome in STEMI patients.3-5 In daily practice, thrombectomy devices are used to remove thrombi or to prevent embolization of thrombi and plaque during PPCI.6 Platelet volume is a marker of platelet activation and is measured via mean platelet volume (MPV).7 An increase in MPV can occur in cases of acute myocardial ischemia, acute myocardial infarction, coronary atherosclerosis,8,9 and early stent thrombosis (ST).10 The Percutaneous Coronary Intervention in Acute Myocardial Infarction (TAPAS) study5 showed that TA therapy during PPCI decreases mortality and reinfarction rate.5 We speculate that the good results obtained with TA therapy are not only related to improved tissue perfusion but also may be related to reduced platelet activation. Therefore, the present study aimed to determine the effect of thrombectomy on platelet function and ST in patients undergoing PPCI for STEMI.  相似文献   
59.
With the increase in life expectancy, cardiovascular complications of cystic fibrosis (CF) have come to the forefront. Increased arterial stiffness is a marker of increased cardiovascular risk. The aim of this study was to compare both pulse wave velocity (PWV) and augmentation index (Aix) measurements in children with CF and to compare them with healthy controls. We hypothesized that children with CF had increased arterial stiffness, although traditional risk factors for CVD were not observed. Forty‐four patients and age and sex‐matched 30 healthy controls were included in the study. Hemodynamic measurements were compared in both groups, together with traditional risk factors. Peripheral blood pressure parameters of CF and control groups were similar (P > .05). Bodyweight and BMI were significantly lower in the CF group (P < .001). Serum cholesterol, HDL, and LDL levels were significantly lower in the CF group, whereas fasting blood glucose and triglyceride levels were significantly higher than the control group (P < .05). Mean ± SD Aix was significantly higher in the CF group (33.22 ± 13.87%) compared with the control group (24.93 ± 10.58%), respectively (P < .05), while PWV was similar. No significant correlation between PWV and Aix and fasting blood glucose and lipid profile in both groups (P > .05). Children with CF have been shown to have increased arterial stiffness compared to healthy children. Although there are not many traditional risk factors, increased arterial stiffness have been demonstrated in children with CF. The effects of this process starting from childhood on the development of CVD in adulthood are not known. Therefore, further studies are needed.  相似文献   
60.
Chronic hepatitis C (CHC) patients with treatment failure (TF) remain at risk of continuing fibrosis progression. However, it has not been investigated whether there is an increased risk of accelerated fibrosis progression after failed interferon‐based therapy. We aimed to investigate long‐term influence of TF on fibrosis progression compared with untreated patients with CHC. We studied 125 patients with CHC who underwent paired liver biopsies from 1994 to 2012. Patients with advanced fibrosis were excluded from the analysis. Sixty‐three patients had TF, and 62 patients were treatment‐naïve (TN). Annual fibrosis progression rate (FPR) was calculated, and significant fibrosis progression (SFP) was defined as ≥2 stage increase in fibrosis during follow‐up. Multiple regression analyses were performed to find out independent predictors of FPR and SFP. Demographic characteristics and duration between paired liver biopsies were similar in TF and TN groups. Baseline alanine aminotransferase and gamma‐glutamyl transferase (GGT) levels (71 ± 31 vs 47 ± 22, P < 0.001 and 49 ± 39 vs 36 ± 28, P = 0.027, respectively), baseline mean fibrosis stage (2.2 ± 0.7 vs 1.9 ± 0.7, P = 0.018) and histologic activity index (6.3 ± 1.9 vs 4.3 ± 1.6, P < 0.001) were higher in the TF group compared with the TN group. In regression analyses, the strongest independent predictor of fibrosis progression was the GGT level (OR: 1.03, 95%CI 1.01–1.5, P < 0.001). Treatment experience (OR: 5.97, 95%CI 1.81–19.7, P = 0.003) also appeared as an independent predictor of both FPR and SFP. Failed interferon‐based CHC treatment may lead to accelerated FPR in the long‐term compared with the natural course.  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