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   1924篇
  免费   112篇
  国内免费   15篇
耳鼻咽喉   27篇
儿科学   51篇
妇产科学   38篇
基础医学   311篇
口腔科学   118篇
临床医学   135篇
内科学   427篇
皮肤病学   47篇
神经病学   105篇
特种医学   82篇
外科学   208篇
综合类   10篇
预防医学   225篇
眼科学   22篇
药学   115篇
中国医学   35篇
肿瘤学   95篇
  2024年   4篇
  2023年   17篇
  2022年   42篇
  2021年   62篇
  2020年   69篇
  2019年   69篇
  2018年   76篇
  2017年   69篇
  2016年   60篇
  2015年   67篇
  2014年   86篇
  2013年   125篇
  2012年   190篇
  2011年   168篇
  2010年   102篇
  2009年   68篇
  2008年   90篇
  2007年   98篇
  2006年   94篇
  2005年   79篇
  2004年   46篇
  2003年   52篇
  2002年   42篇
  2001年   38篇
  2000年   32篇
  1999年   21篇
  1998年   12篇
  1997年   10篇
  1996年   5篇
  1995年   6篇
  1994年   4篇
  1993年   8篇
  1992年   14篇
  1991年   9篇
  1990年   5篇
  1989年   8篇
  1988年   11篇
  1987年   18篇
  1986年   10篇
  1985年   11篇
  1984年   6篇
  1983年   7篇
  1982年   4篇
  1980年   3篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1971年   2篇
  1970年   5篇
  1969年   4篇
排序方式: 共有2051条查询结果,搜索用时 15 毫秒
21.
22.
In patients with Mansoni schistosomiasis, it is fundamental to evaluate the disease morbidity, which is reflected by the severity of periportal fibrosis (PPF) and parameters of portal hypertension, as analyzed by ultrasonography (US). This study aimed to evaluate the morbidity of schistosomiasis by hepatic and splenic point shear-wave elastography (pSWE) and relate this to US parameters. The PPF pattern, the diameter of the portal and splenic veins and the size of the spleen were evaluated by US. Then, liver and spleen pSWEs were assessed in 74 patients using the same equipment. As the PPF pattern progressed, the splenic pSWE values significantly increased. Significant correlations between splenic pSWE, the longitudinal and transverse lengths of the spleen and the diameters of the portal and splenic veins were observed. These findings, however, were not observed through hepatic pSWE. In conclusion, the splenic pSWE has the potential for assessing morbidity in schistosomiasis mansoni.  相似文献   
23.
Abstract

Cellulose is a renewable polymer quite abundant on the Earth and very attractive for applications in the construction of eco-friendly biomedical products. The aim of this study was to investigate the chemical-physical characteristics of cotton cellulose nanofiber (CCN)/chitosan nanocomposite and its cytocompatibility with human embryonic kidney cells. First, the chemical composition, swelling ratio and surface topography of the nanocomposite were evaluated. Cytocompatibility was then assessed through spreading, proliferation and viability of cells. The experimental results showed that the CCN was an effective nanomaterial agent for increasing the roughness surface of chitosan film. Cell proliferation and changes in cell morphology indicated that the nanocomposite led to improved cell spreading and growth. Cell viability did not decrease after 24?h. However, the cell survival on the nanocomposite was affected at 72?h. The results indicate that CCN/chitosan nanocomposite could be a promising biocompatible biomaterial for biomedical applications.  相似文献   
24.
25.
This study investigated the effect of irradiation with an erbium‐doped yttrium aluminium garnet (Er:YAG) laser and coating with silica on the surface characteristics, bond strength, and flexural strength of dental zirconia. Three hundred and forty‐three standard zirconia specimens were created, and 49 were assigned to each of seven surface treatment groups: (i) no treatment; Er:YAG laser (80 mJ/2 Hz) with pulse widths of 50 μs (ii), 100 μs (iii), 300 μs (iv), or 600 μs (v); or tribochemical silica coating at the partially sintered stage (vi) or after sintering was complete (vii). All specimens were sintered after the surface treatments, except for the group in which specimens were sintered before treatment. The study outcomes were roughness, surface loss, microshear bond strength (μSBS), and biaxial flexural strength (BFS). Mean roughness and surface loss values were significantly higher in specimens from irradiated groups than in those from silica‐coated groups. Regarding μSBS, after aging, specimens from all experimental groups presented very low and similar μSBS values, irrespective of the surface treatment. Silica coating after sintering yielded the highest BFS (1149.5 ± 167.6 MPa), while coating partially sintered specimens with silica resulted a BFS (826.9 ± 60.9 MPa) similar to that of the untreated control group (794.9 ± 101.7 MPa). Laser treatments, irrespective of pulse width used, significantly decreased the BFS. In the group treated with laser at 300 μs pulse width, specimens exhibited the lowest BFS value (514.1 ± 71.5 MPa). Adhesion to zirconia was not stable after aging, regardless of the surface treatment implemented.  相似文献   
26.
27.
28.
Idiopathic Atrophoderma of Pasini and Pierini (IAPP) is a rare, exclusively cutaneous disease. It is more frequent in females, with incidence peak in the second and third decades of life. The etiopathogenesis remains unknown. IAPP most commonly affects the back, abdomen and proximal regions of the limbs. Lesions may be rounded, oval or circular; single or multiple. The evolution is variable and the course is initially progressive. Collagen changes such as atrophy, thinning, condensation and sclerosis may be observed in the papillary dermis. This paper describes a case of Idiopathic Atrophoderma of Pasini and Pierini with histopathologic findings.  相似文献   
29.
30.
ObjectivesA proof-of-concept study was undertaken to determine whether differences in corrected coronary opacification (CCO) within coronary lumen can identify arteries with abnormal resting coronary flow.BackgroundAlthough computed tomographic coronary angiography can be used for the detection of obstructive coronary artery disease, it cannot reliably differentiate between anatomical and functional stenoses.MethodsComputed tomographic coronary angiography patients (without history of revascularization, cardiac transplantation, and congenital heart disease) who underwent invasive coronary angiography were enrolled. Attenuation values of coronary lumen were measured before and after stenoses and normalized to the aorta. Changes in CCO were calculated, and CCO differences were compared with severity of coronary stenosis and Thrombolysis In Myocardial Infarction (TIMI) flow at the time of invasive coronary angiography.ResultsOne hundred four coronary arteries (n = 52, mean age = 60.0 ± 9.5 years; men = 71.2%) were assessed. Compared with normal arteries, the CCO differences were greater in arteries with computed tomographic coronary angiography diameter stenoses ≥50%. Similarly, CCO differences were greater in arteries with TIMI flow grade <3 (0.406 ± 0.226) compared with those with normal flow (TIMI flow grade 3) (0.078 ± 0.078, p < 0.001). With CCO differences, abnormal coronary flow (TIMI flow grade < 3) was identified with a sensitivity and specificity, positive predictive value, and negative predictive value of 83.3% (95% confidence interval [CI]: 57.7 to 95.6%), 91.2% (95% CI: 75.2% to 97.7%), 83.3% (95% CI: 57.7% to 95.6%), and 91.2% (95% CI: 75.2% to 97.7%), respectively. Accuracy of this method was 88.5% with very good agreement (kappa = 0.75, 95% CI: 0.55 to 0.94).ConclusionsChanges in CCO across coronary stenoses seem to predict abnormal (TIMI flow grade < 3) resting coronary blood flow. Further studies are needed to understand its incremental diagnostic value and its potential to measure stress coronary blood flow.  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