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   3690篇
  免费   143篇
  国内免费   30篇
耳鼻咽喉   44篇
儿科学   250篇
妇产科学   190篇
基础医学   285篇
口腔科学   119篇
临床医学   321篇
内科学   779篇
皮肤病学   105篇
神经病学   264篇
特种医学   175篇
外科学   707篇
综合类   38篇
预防医学   106篇
眼科学   175篇
药学   183篇
  1篇
中国医学   1篇
肿瘤学   120篇
  2024年   3篇
  2023年   37篇
  2022年   57篇
  2021年   83篇
  2020年   48篇
  2019年   56篇
  2018年   90篇
  2017年   79篇
  2016年   126篇
  2015年   118篇
  2014年   145篇
  2013年   252篇
  2012年   282篇
  2011年   303篇
  2010年   156篇
  2009年   138篇
  2008年   293篇
  2007年   302篇
  2006年   286篇
  2005年   296篇
  2004年   240篇
  2003年   148篇
  2002年   141篇
  2001年   40篇
  2000年   25篇
  1999年   33篇
  1998年   15篇
  1997年   11篇
  1996年   6篇
  1995年   5篇
  1994年   7篇
  1993年   3篇
  1992年   3篇
  1991年   4篇
  1990年   4篇
  1989年   8篇
  1985年   10篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1973年   2篇
  1970年   1篇
排序方式: 共有3863条查询结果,搜索用时 12 毫秒
51.

Background

Polycystic ovary syndrome (PCOS) is related to metabolic syndrome, insulin resistance, and cardiovascular metabolic syndromes. This is particularly true for individuals with central and abdominal obesity because visceral abdominal adipose tissue (VAAT) and epicardial adipose tissue (EAT) produce a large number of proinflammatory and proatherogenic cytokines. The present study aimed to determine whether there are changes in VAAT and EAT levels which were considered as indirect predictors for subclinical atherosclerosis in lean patients with PCOS.

Methods

The clinical and demographic characteristics of 35 patients with PCOS and 38 healthy control subjects were recorded for the present study. Additionally, the serum levels of various biochemical parameters were measured and EAT levels were assessed using 2D-transthoracic echocardiography.

Results

There were no significant differences in mean age (p?=?0.056) or mean body mass index (BMI) (p?=?0.446) between the patient and control groups. However, the body fat percentage, waist-to-hip ratio, amount of abdominal subcutaneous adipose tissue, and VAAT thickness were higher in the PCOS patient group than in the control group. The amounts of EAT in the patient and control groups were similar (p?=?0.384). EAT was correlated with BMI, fat mass, waist circumference, and hip circumference but not with any biochemical metabolic parameters including the homeostasis model assessment of insulin resistance index or the levels of triglycerides, low-density lipoprotein cholesterol, and high-density lipoprotein (HDL) cholesterol. However, there was a small positive correlation between the amounts of VAAT and EAT. VAAT was directly correlated with body fat parameters such as BMI, fat mass, and abdominal subcutaneous adipose thickness and inversely correlated with the HDL cholesterol level.

Conclusions

The present study found that increased abdominal adipose tissue in patients with PCOS was associated with atherosclerosis. Additionally, EAT may aid in the determination of the risk of atherosclerosis in patients with PCOS because it is easily measured.
  相似文献   
52.
53.
In this study, we aimed to compare the effects of forced-air warming upper body blankets and forced-air warming underbody blankets on intraoperative hypothermia in patients who were planned to undergo open abdominal surgical operations in which extensive heat loss occurs. This prospective and randomized study included 92 patients who would undergo lower abdominal surgery under general anesthesia. Patients were randomized by closed envelope method and divided into two groups. Group I (n:46) included the patients who would receive warming with forced-air warming upper body blanket, and Group II (n:46) consisted of the patients who received warming with forced-air warming underbody blanket. Central body temperature was recorded by measuring with a temperature probe placed in distal esophagus. Demographic data, amount of fentanyl, crystalloid and blood products used, duration of operation, type of operation, hemodynamic parameters, shivering and thermal damage information were recorded. There was not any statistically significant difference among the patients in terms of demographic data, amount of fentanyl, crystalloid and blood products used, duration and type of operation and hemodynamic parameters. No difference was found between the groups in terms of body temperatures (Group I:36.1?°C, Group II:36.3?°C, respectively) (P?>?0.05). Forced air warming underbody blanket can be as effective as forced-air warming upper body blankets in preventing intraoperative hypothermia. They can be alternative in cases where use of forced-air warming upper body blankets is not feasible.  相似文献   
54.
Severe neutropenia-associated invasive bacterial or fungal infections are still the major cause of mortality and morbidity in children receiving cancer chemotherapy. Granulocyte transfusion therapy has been used for many years in the management of neutropenic patients with severe infections in whom the clinical condition deteriorated despite appropriate antimicrobial treatment. Transfused granulocytes can increase the recipient’s blood neutrophil count and accumulation of them into the site of infection. There are some data obtained from retrospective or prospective observational studies in pediatric granulocyte transfusion therapy, but results are not conclusive. This review appraises the potential benefits and risks of the use of granulocyte transfusion in children with neutropenic fever.  相似文献   
55.
56.
57.

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by arterial and/ or venous thrombosis accompanied by persistently elevated levels of antiphospholipid antibodies (aPLs). The aim of this study is to evaluate the pulmonary manifestations of APS and compare the levels of aPLs in patients with and without pulmonary involvement. We retrospectively reviewed the files of patients with the diagnosis of APS between October 2010 and May 2017. Demographic data, clinical, radiological and laboratory findings were recorded. The study included 67 patients (56 female/11 male) with a mean age of 39?±?13 years. Pulmonary manifestations such as parenchymal and/or vascular involvement were seen in 12 (17.9%) patients. The patients with and without pulmonary manifestations were not significantly different in terms of age (p?=?0.46), comorbidities (p?=?0.48) and APS duration (p?=?0.66). Acute pulmonary thromboembolism (PE) was determined in 11 (16.4%), alveolar hemorrhage in 2 (3%) patients. Four patients with acute PE (36%) developed chronic thromboembolic pulmonary hypertension (CTEPH). One patient developed both CTEPH and diffuse alveolar hemorrhage after acute PE during follow up. Antiphosholipid antibody IgM was highly positive in patients with PE compared to patients without PE (p?=?0.005). Other antibodies and lupus anticoagulant were not significantly different in patients with and without PE. None of the patients were deceased due to pulmonary manifestations of APS. PE was the most common pulmonary manifestation of APS. The development of CTEPH was high among APS patients. Patients with APS should be closely followed for the onset of PE and CTEPH.

  相似文献   
58.
Purpose

Hypophysitis is a heterogeneous condition that includes inflammation of the pituitary gland and infundibulum, and it can cause symptoms related to mass effects and hormonal deficiencies. We aimed to evaluate the potential role of machine learning methods in differentiating hypophysitis from non-functioning pituitary adenomas.

Methods

The radiomic parameters obtained from T1A-C images were used. Among the radiomic parameters, parameters capable of distinguishing between hypophysitis and non-functioning pituitary adenomas were selected. In order to avoid the effects of confounding factors and to improve the performance of the classifiers, parameters with high correlation with each other were eliminated. Machine learning algorithms were performed with the combination of gray-level run-length matrix-low gray level run emphasis, gray-level co-occurrence matrix-correlation, and gray-level co-occurrence entropy.

Results

A total of 34 patients were included, 17 of whom had hypophysitis and 17 had non-functioning pituitary adenomas. Among the 38 radiomics parameters obtained from post-contrast T1-weighted images, 10 tissue features that could differentiate the lesions were selected. Machine learning algorithms were performed using three selected parameters; gray level run length matrix-low gray level run emphasis, gray-level co-occurrence matrix-correlation, and gray level co-occurrence entropy. Error matrices were calculated by using the machine learning algorithm and it was seen that support vector machines showed the best performance in distinguishing the two lesion types.

Conclusions

Our analysis reported that support vector machines showed the best performance in distinguishing hypophysitis from non-functioning pituitary adenomas, emphasizing the importance of machine learning in differentiating the two lesions.

  相似文献   
59.
Tetanus is a preventable disease that continues to affect people in both developing and developed countries. The aim of the present study was to evaluate the immunity profile to tetanus in patients with Type II diabetes mellitus (DM) and to compare them with healthy controls. The tetanus antitoxin levels in 310 diabetic patients (104 males and 206 females) and in 200 healthy controls (72 males and 128 females) were measured by ELISA (Virotech, Germany). The mean antitoxin concentration in patient and control groups were 0.8238+/-1.61 and 0.9978+/-1.49 IU/ml, respectively. There was a statistically significant difference between the two groups (z=-3.520, P=.0001 and odds ratio was 2.367). There was a definitive inverse correlation between the duration of diabetes and tetanus antibody titers (Spearman's correlation analysis, r=-.155, P=.006). A gender-dependent difference in the susceptibility to tetanus was present in the diabetic group with antibody titers being significantly higher in males compared with females (z=-2.267, P=.023). For both of control (chi(2)=20.207, P=.003) and patient (chi(2)=43.532, P=.0001) groups, there was a significant inverse correlation between the tetanus immunity levels and age. Statistically, a significant drop in antibody titers of both groups was found as the period past from the last immunization increased (Pearson correlation analysis: for patient group r=-.364, P=.0001; for control group r=-.143, P=.044). The tetanus antitoxin levels were significantly increased in individuals who had primary immunization during childhood (for patient group chi(2)=17.191, P=.0001; for control group chi(2)=9.911, P=.007). A significant reduction in the level of antitoxin immunity to tetanus in association with an increased susceptibility to infections in patients with diabetes may implicate the need for improving vaccination rates in this patient group.  相似文献   
60.
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