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   3216篇
  免费   236篇
  国内免费   9篇
耳鼻咽喉   89篇
儿科学   90篇
妇产科学   46篇
基础医学   333篇
口腔科学   407篇
临床医学   216篇
内科学   705篇
皮肤病学   95篇
神经病学   254篇
特种医学   68篇
外科学   597篇
综合类   8篇
预防医学   262篇
眼科学   31篇
药学   178篇
中国医学   13篇
肿瘤学   69篇
  2023年   29篇
  2022年   40篇
  2021年   107篇
  2020年   83篇
  2019年   99篇
  2018年   148篇
  2017年   82篇
  2016年   114篇
  2015年   120篇
  2014年   136篇
  2013年   177篇
  2012年   196篇
  2011年   256篇
  2010年   151篇
  2009年   132篇
  2008年   160篇
  2007年   182篇
  2006年   157篇
  2005年   135篇
  2004年   127篇
  2003年   96篇
  2002年   92篇
  2001年   64篇
  2000年   70篇
  1999年   55篇
  1998年   23篇
  1997年   11篇
  1996年   10篇
  1995年   15篇
  1994年   10篇
  1993年   10篇
  1992年   28篇
  1991年   34篇
  1990年   28篇
  1989年   19篇
  1988年   10篇
  1987年   18篇
  1986年   19篇
  1985年   23篇
  1984年   14篇
  1983年   10篇
  1980年   9篇
  1979年   16篇
  1974年   12篇
  1973年   11篇
  1971年   12篇
  1970年   14篇
  1969年   14篇
  1968年   17篇
  1967年   11篇
排序方式: 共有3461条查询结果,搜索用时 546 毫秒
71.
Background

Since HLA-G is an immune checkpoint molecule and since Crohn’s disease (CD) and ulcerative colitis (UC) exhibit deregulated immune-mediated mechanisms, we aimed to evaluate intestinal HLA-G expression and soluble HLA-G (sHLA-G) levels in CD/UC patients stratified according to the CD phenotype/localization and UC extension.

Methods

HLA-G tissue expression was assessed by immunohistochemistry in biopsies collected from 151 patients (90 CD, 61 UC) and in surgical resection specimens (28 CD, 12 UC). Surgical material from 24 healthy controls was also assessed. Plasma sHLA-G levels (97 CD, 81 UC, and 120 controls) were evaluated using ELISA.

Results

HLA-G expression was similarly observed in the intestinal epithelial cells of control and CD/UC specimens. However, in biopsies, the plasma cells/lymphocytes infiltrating the lamina propria in CD/UC presented (1) increased HLA-G expression compared to controls (P?<?0.0001), (2) greater cell staining in UC cells than in CD cells irrespective of disease extent (P?=?0.0011), and (3) an increased number of infiltrating cells in the inflammatory CD phenotype compared to that in the stenosing and fistulizing phenotypes (P?=?0.0407). In surgical specimens, CD/UC patients exhibited higher infiltrating cell HLA-G expression in lesion areas than in margins. sHLA-G levels were higher in UC/CD patients (P?<?0.0001) than in controls, but no difference was observed between diseases.

Conclusions

Increased infiltrating cell HLA-G expression associated with increased sHLA-G levels in CD/UC patients may reflect ongoing host strategies to suppress chronic inflammation.

  相似文献   
72.
BackgroundCardiomegaly on chest X-ray is an independent predictor of death in individuals with chronic Chagas cardiomyopathy (CCC). However, the correlation between increased cardiothoracic ratio (CTR) on chest X-ray and left ventricular end-diastolic diameter (LVEDD) on echocardiography is not well established in this population.ObjectivesTo assess the relationship between chest X-ray and LVEDD on echocardiography in patients with Chagas disease and its applicability to the Rassi score.MethodsRetrospective study on 63 Chagas disease outpatients who underwent chest X-ray and echocardiography. Cardiomegaly on chest X-ray was defined as a CTR>0.5. LVEDD was analyzed as a continuous variable. ROC curve was used to evaluate the ability of LVEDD in detecting cardiomegaly by chest X-ray, with a cut-off point defined by the highest sum of sensitivity and specificity.ResultsMedian age 61 years [interquartile range 48-68], 56% were women. CCC was detected in 58 patients, five patients had the indeterminate form of Chagas disease. Cardiomegaly was detected in 28 patients. The area under the ROC curve for LVEDD was 0.806 (95%CI: 0.692-0.919). The optimal cut-off for LVEDD was 60 mm (sensitivity = 64%, specificity = 89%). The use of LVEDD on echocardiography as a surrogate for CTR on chest X-ray changed the Rassi score values of 14 patients, with a reduction in the presumed risk in 10 of them.ConclusionLVEDD on echocardiography is an appropriate, highly specific parameter to distinguish between the presence and absence of cardiomegaly on chest X-ray in Chagas disease. (Arq Bras Cardiol. 2021; 116(1):68-74)  相似文献   
73.
To describe a single‐center experience with kidney transplantation and then study some donor and recipient features that may impact on graft survival and urological complication rates. We reviewed our database searching for pediatric patients who underwent kidney transplantation from August 1985 through November 2012. Preoperative data and postoperative complications were recorded. Graft survival rates were analyzed and compared based on the type of donor, donor's age from deceased donors, and recipients' ESRD cause. Kaplan–Meier curves with log rank and Wilcoxon tests were used to perform the comparisons. There were 305 pediatric kidney transplants. The mean recipient's age was 11.7 yr. The mean follow‐up was 11.0 yr. Arterial and venous thrombosis rates were 1.6% and 2.3%, respectively, while urinary fistula and symptomatic vesicoureteral reflux were diagnosed in 2.9% and 3.6% of cases, respectively. Deceased kidney transplantation had a lower graft survival rate than living kidney transplantation (log rank, p = 0.005). Donor's age (p = 0.420) and ESRD cause (p = 0.679) were not significantly related to graft survival rate. In long‐term follow‐up, type of donor, but not donor's age, impacts on graft survival rate. ESRD cause has no impact on graft survival rate, showing that well‐evaluated recipients may have good outcomes.  相似文献   
74.
Mixed oxides of aluminum and magnesium derived from hydrotalcites were prepared by means of a sol–gel method mediated by an emulsified sol as pore template. The emulsion consisted of ethanol as the continuous phase and n-dodecane droplets as the dispersed phase, which was stabilized by the presence of the surfactant Pluronic P123. The use of such an emulsion was essential for obtaining materials with a porous structure that were assessed by mercury intrusion porosimetry and nitrogen physisorption. Additional characterization by NH3 and CO2 temperature programmed desorption confirmed that despite the enhancement of their textural properties, the number of acid and base sites was reduced in comparison to a reference and conventionally prepared Al–Mg mixed oxide, as a consequence of the depletion of surface hydroxyls during condensation of the precursors around the nonpolar droplets of the emulsion. Catalytic conversion of 2-propanol under conditions of controlled mass and heat diffusion on the texturally improved Al–Mg mixed oxides evidenced the preparation of a more effective catalyst than the poorly porous reference.

Mixed oxides of aluminum and magnesium derived from hydrotalcites that were prepared by means of a sol–gel method mediated by an emulsified sol as pore template.  相似文献   
75.
76.
77.

Objectives

To compare the effects of functional training, bicycle exercise, and exergaming on walking capacity of elderly with Parkinson disease (PD).

Design

A pilot randomized, controlled, single-blinded trial.

Setting

A state reference health care center for elderly, a public reference outpatient clinic for the elderly.

Participants

Elderly individuals (≥60 years of age; N=62) with idiopathic PD (stage 2 to 3 of modified Hoehn and Yahr staging scale) according to the London Brain Bank.

Intervention

The participants were randomly assigned to three groups. Group 1 (G1) participated in functional training (n=22); group 2 (G2) performed bicycle exercise (n=20), and group 3 (G3) trained with Kinect Adventures (Microsoft, Redmond, WA) exergames (n=20).

Main Outcome Measures

The primary outcome measure was the 6-minute walk test (6MWT); secondary outcome measures were the 10-m walk test (10MWT), sitting-rising test (SRT), body mass index, Parkinson Disease Questionnaire-39, World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0), and 15-item Geriatric Depression Scale.

Results

All groups showed significant improvements in 6MWT (G1 P=.008; G2 P=.001; G3 P=.005), SRT (G1 P<.001; G2 P=.001; G3 P=.003), and WHODAS 2.0 (G1 P=.018; G2 P=.019; G3 P=.041). Only G3 improved gait speed in 10MWT (P=.11). G1 (P=.014) and G3 (P=.004) improved quality of life. No difference was found between groups.

Conclusions

Eight weeks of exergaming can improve the walking capacity of elderly patients with PD. Exergame training had similar outcomes compared with functional training and bicycle exercise. The three physical exercise modalities presented significant improvements on walking capacity, ability to stand up and sit, and functionality of the participants.  相似文献   
78.
Journal of Interventional Cardiac Electrophysiology - Delineate retrospectively and prospectively the incidence and characteristics of transient ST-segment elevation during transseptal puncture....  相似文献   
79.
AIM: To analyze the risk of cardiovascular complications in patients with indication for surgical treatment of Chagasic esophageal achalasia and to correlate the surgical risks with the degree of esophageal dilation, thereby proposing a risk scale index. METHODS: One hundred and twenty-four patients with Chagasic esophageal achalasia, who received surgical treatment at the Hospital das Clinicas of the Federal University of Goias, were included in this study. The patients were mostly related to the postoperative complications due to the cardiovascular system. All the patients were submitted to: (1) clinical history to define the cardiac functional class (New York Heart Association); (2) conventional 12-lead electrocardiogram at rest; and (3) contrast imaging of the esophagus to determine esophageal dilatation according to Rezende's classification of Chagasic megaesophagus. RESULTS: An assessment of the functional classification (FC) of heart failure during the preoperative period determined that 67 patients (54.03%) were assigned functional class I (FC I), 46 patients (37.09%) were assigned functional class II (FC II), and 11 patients (8.87%) were assigned functional class III (FC III). None of the patients were assigned to functional class IV (FC IV). There was a positive correlation between the functional class and the postoperative complications (FC IXFC II: P<0.001; FC IXFC III: P<0.001). The ECG was normal in 44 patients (35.48%) and presented abnormalities in 80 patients (64.52%). There was a significant statistical correlation between abnormal ECG (arrhythmias and primary change in ventricular repolarization) and postoperative complications (P<0.001). With regard to the classification of the Chagasic esophageal achalasia, the following distribution was observed: group II, 53 patients (42.74%); group III, 37 patients (29.83%); and group IV, 34 patients (27.41%). There was a positive correlation between the degree of esophageal dilation and the increase in postoperative complications (grade IIXgrade III achalasia: P<0.001; grade IIXgrade IV achalasia: P<0.001; and grade IIIXgrade IV achalasia: P = 0.017). Analyzing these results and using a multivariate regression analysis associated with the probability decision analysis, a risk scale was proposed as follows: up to 21 points (mild risk); from 22 to 34 points (moderate risk); and more than 34 points (high risk). The scale had 82.4% accuracy for mild risk patients and up to 94.6% for the high risk cases. CONCLUSION: The preoperative evaluation of the cardiovascular system, through a careful anamnesis, an ECG and contrast imaging of the esophagus, makes possible to estimate the surgical risks for Chagas' disease patients who have to undergo surgical treatment for esophageal achalasia.  相似文献   
80.
α‐Thalassemia is a synthesis hemoglobinopathy with a worldwide distribution. α‐thalassemia‐23.7kb (α‐Thal23.7kb) was investigated by PCR and standard hematologic analysis techniques in 106 pregnant women – 53 heterozygous for hemoglobin (Hb) A and C (AC) and 53 homozygous for the normal Hb A (AA) with similar ages and race ancestry. Eleven (21%) of AC women were α‐Thal23.7kb heterozygous and 1 (2%) was homozygous, while 12 AA women (23%) were heterozygous. In the AA group, the MCV differed among those with normal α genes and those with α‐Thal23.7kb (P = 0.031). Statistical analysis of AC group patients with normal α genes and α‐Thal23.7kb carriers showed differences in MCV (P = 0.001); MCH (P = 0.003) and Hb C concentrations (P = 0.011). Analysis of AA and AC group patients with normal α genes showed differences in RBC (P = 0.033), Hb concentration (P = 0.003) and MCHC (P < 0.0001). There were no statistically significant differences for any hematologic parameters between AC and AA group patients with the α‐Thal23.7kb genotype. The AC α‐Thal23.7kb homozygous women had low hematologic parameters. Serum ferritin levels were normal among the groups studied. These results emphasize the importance of diagnosis and follow‐up of patients with hemoglobinopathy carriers during pregnancy in order to administer adequate therapy and avoid further complications for mothers and newborns.  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