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   2689篇
  免费   216篇
  国内免费   11篇
耳鼻咽喉   21篇
儿科学   101篇
妇产科学   112篇
基础医学   410篇
口腔科学   88篇
临床医学   339篇
内科学   548篇
皮肤病学   117篇
神经病学   150篇
特种医学   40篇
外科学   183篇
综合类   52篇
一般理论   4篇
预防医学   222篇
眼科学   70篇
药学   223篇
中国医学   50篇
肿瘤学   186篇
  2024年   7篇
  2023年   49篇
  2022年   146篇
  2021年   223篇
  2020年   164篇
  2019年   189篇
  2018年   188篇
  2017年   107篇
  2016年   140篇
  2015年   115篇
  2014年   156篇
  2013年   187篇
  2012年   245篇
  2011年   233篇
  2010年   115篇
  2009年   81篇
  2008年   113篇
  2007年   103篇
  2006年   87篇
  2005年   90篇
  2004年   59篇
  2003年   31篇
  2002年   30篇
  2001年   4篇
  2000年   1篇
  1999年   6篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   3篇
  1993年   2篇
  1991年   1篇
  1990年   1篇
  1988年   5篇
  1987年   7篇
  1986年   2篇
  1985年   5篇
  1984年   2篇
  1980年   1篇
  1979年   4篇
  1977年   1篇
  1976年   1篇
  1973年   2篇
  1936年   1篇
排序方式: 共有2916条查询结果,搜索用时 31 毫秒
41.
Cyclic neutropenia is a rare immunodeficiency syndrome, characterized by regular periodic oscillations in the circulating neutrophil count from normal to neutropenic levels through 3 weeks period, and lasting for 3-6 days. In order to determine the clinical features of cyclic neutropenia, this study was performed. Seven patients with cyclic neutropenia (3 males and 4 females), who experienced neutropenic periods every 3 weeks (5 with severe and 2 with moderate neutropenia), were investigated in this study. They had been referred to Iranian Primary Immunodeficiency Registry during 23 years (1980-2003). The range of patients' ages was from 7 to 13 years (median 11 years). The median age at the onset of the disease was 12 months (1 month- 2 years) and the median age of diagnosis was 2 (1.5-5) years, with a median diagnosis delay of 1 year (2 months- 5 years). Neutropenia was associated with leukopenia (3 patients), anemia (3 patients), and thrombocytopenia (1 patient). Patients were asymptomatic in healthy phase, but during the episode of neutropenia suffered from aphthous ulcers, abscesses and overwhelming infections. The most commonly occurred manifestations were: otitis media (6 cases), oral ulcers (5 cases), abscesses (4 cases), pneumonia (3 cases), diarrhea (3 cases), oral candidiasis (3 cases), cutaneous infections (2 cases), and periodontitis (2 cases). One of these patients subsequently died because of recurrent infections. Unusual, persistent or severe infections should be the initiating factors to search for an immune deficiency syndrome such as cyclic neutropenia, because a delay in diagnosis may result in chronic infection, irretrievable end-organ damage or even death of the patient.  相似文献   
42.
Objective We conducted this study to compare the rate of ≥1 inappropriate therapy between ICDs from two manufacturers which use different discriminatory protocols. Method One hundred sixty two patients (mean age 58 ± 13 years, 126 male) who received ICDs between January 2001 and 2005 were included in the study. Clinical, electrocardiographic, and ICD stored data and electrograms were collected and analyzed. Immediately after implantation all the detection and discrimination criteria were activated with the nominal values in order to compare the two discriminatory protocols under the default manufacturer’s settings. Results During the follow up period of 14.3 ± 10 months, 49 (30%) patients received ≥1 inappropriate ICD therapy. The rate of ≥1 inappropriate ICD therapy in manufacturer A and B ICDs was 26% (n = 29) and 41% (n = 20), respectively. Comparing the rate of ≥1 inappropriate ICD therapy between the two groups by Kaplan–Meier analysis and the log rank test resulted in P = 0.04. Conclusion Having all discriminatory variables activated with the nominal values, discriminatory performance differs between the two manufacturers. Further larger-scale studies are warranted to prospectively compare the performance of various available ICDs’ discriminatory protocols, and define the optimum combination of discriminators in each ICD to decrease the rate of inappropriate therapy.  相似文献   
43.
ObjectiveWe evaluated the efficacy of spinal manipulation for the management of nonacute lumbar radiculopathy.MethodsIn a university hospital we performed a randomized controlled trial with 2 parallel arms. Patients (n = 44) with unilateral radicular low back pain lasting more than 4 weeks were randomly allocated to manipulation and control groups. The primary outcome was the intensity of the low back pain on a visual analog scale. The secondary outcome was the Oswestry Disability Questionnaire score. We also measured spinal ranges of motion. The assessments were carried out at the baseline, immediately after intervention, and at 3 months’ follow-up. All patients underwent physiotherapy. The manipulation group received three sessions of manipulation therapy 1 week apart. For manipulation, we used Robert Maigne's technique.ResultsBoth groups experienced a decrease in back and leg pain significantly (all P ≤ 0.003). However, only the manipulation group showed significantly favorable results in the Oswestry scores (P < 0.001), and the straight leg raise test (P = 0.001). All ranges of motion increased significantly with manipulation (all P < 0.001), but the control group showed favorable results only in right and left rotations and in extension (all P < 0.001). Between-group analyses showed significantly better outcomes for manipulation in all measurements (all P ≤ 0.009) with large effect sizes.ConclusionSpinal manipulation improves the results of physiotherapy over a period of 3 months for patients with subacute or chronic lumbar radiculopathy.  相似文献   
44.
45.
46.
Curve of left ventricular (LV) volume changes throughout the cardiac cycle is a fundamental parameter for clinical evaluation of various cardiovascular diseases. Currently, this evaluation is often performed manually which is tedious and time consuming and suffers from significant interobserver and intraobserver variability. This paper introduces a new automatic method, based on nonlinear dimensionality reduction (NLDR) for extracting the curve of the LV volume changes over a cardiac cycle from two-dimensional (2-D) echocardiography images. Isometric feature mapping (Isomap) is one of the most popular NLDR algorithms. In this study, a modified version of Isomap algorithm, where image to image distance metric is computed using nonrigid registration, is applied on 2-D echocardiography images of one cycle of heart. Using this approach, the nonlinear information of these images is embedded in a 2-D manifold and each image is characterized by a symbol on the constructed manifold. This new representation visualizes the relationship between these images based on LV volume changes and allows extracting the curve of the LV volume changes automatically. Our method in comparison to the traditional segmentation algorithms does not need any LV myocardial segmentation and tracking, particularly difficult in the echocardiography images. Moreover, a large data set under various diseases for training is not required. The results obtained by our method are quantitatively evaluated to those obtained manually by the highly experienced echocardiographer on ten healthy volunteers and six patients which depict the usefulness of the presented method.  相似文献   
47.

Background:

Tertiary pediatric hospitals usually provide excellent clinical services, but such centers have a lot to do for educational perfection.

Objectives:

This study was performed to address under-graduate educational deficits and find feasible solutions.

Patients and Methods:

This cross-sectional study was done in a target population of 77 sixth year undergraduate medical students (response rate = 78%) who spent their 3-month pediatric rotation in the Children’s Medical Center, the Pediatrics Center of Excellence in Tehran, Iran. The Dundee ready educational environment measure (DREEM) instrument was used for assessing educational environment of this subspecialized pediatric hospital.

Results:

Among 60 students who answered the questionnaires, 24 were male (40%). Participants’ age ranged from 23 to 24 years. The mean total score was 95.8 (48%). Comparison of scores based on students’ knowledge showed no significant difference. Problematic areas were learning, academic self-perception, and social self-perception.

Conclusions:

Having an accurate schedule to train general practitioner, using new teaching methods, and providing a non-stressful atmosphere were suggested solutions.  相似文献   
48.
49.
50.
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