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   107606篇
  免费   6486篇
  国内免费   655篇
耳鼻咽喉   1119篇
儿科学   3507篇
妇产科学   2503篇
基础医学   15498篇
口腔科学   4033篇
临床医学   9842篇
内科学   24010篇
皮肤病学   2743篇
神经病学   10561篇
特种医学   2603篇
外国民族医学   1篇
外科学   9992篇
综合类   407篇
一般理论   50篇
预防医学   10455篇
眼科学   1730篇
药学   7571篇
中国医学   428篇
肿瘤学   7694篇
  2024年   86篇
  2023年   964篇
  2022年   856篇
  2021年   3682篇
  2020年   2332篇
  2019年   3134篇
  2018年   3541篇
  2017年   2712篇
  2016年   3152篇
  2015年   3482篇
  2014年   4593篇
  2013年   5996篇
  2012年   9107篇
  2011年   9471篇
  2010年   5170篇
  2009年   4353篇
  2008年   7531篇
  2007年   7496篇
  2006年   6942篇
  2005年   6456篇
  2004年   5824篇
  2003年   5166篇
  2002年   4649篇
  2001年   614篇
  2000年   429篇
  1999年   631篇
  1998年   816篇
  1997年   670篇
  1996年   561篇
  1995年   462篇
  1994年   441篇
  1993年   363篇
  1992年   305篇
  1991年   219篇
  1990年   215篇
  1989年   200篇
  1988年   189篇
  1987年   157篇
  1986年   171篇
  1985年   126篇
  1984年   142篇
  1983年   137篇
  1982年   171篇
  1981年   119篇
  1980年   126篇
  1979年   83篇
  1978年   84篇
  1977年   70篇
  1976年   60篇
  1974年   57篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
71.
Familial Cancer - The risk of radiotherapy-induced malignancies (RIMs) is a concern when treating Li–Fraumeni syndrome (LFS) or Li–Fraumeni Like (LFL) patients. However, the type of...  相似文献   
72.
73.
74.
75.
76.

Background

Total ankle replacement (TAR) represents an alternative to fusion for the treatment of end-stage ankle osteoarthritis. The aim of the present study was to retrospectively assess the frequency of infections between TARs with anterior and lateral transfibular approach at 12-months follow-up.

Methods

81 TARs through an anterior approach and 69 TARs through a lateral approach were performed between May 2011 and July 2015. We compared surgical time and tourniquet time, as well as superficial and deep infections frequency during the first 12 postoperative months.

Results

In the anterior approach group, there were 3 (3.7%) deep infections and 4 (4.9%) superficial wound infections. In the lateral approach group, there were 1 (1.4%) deep infection and 2 superficial wound infections (2.9%). There were not statistically significant differences between the groups. There was a significant difference between anterior approach (115 minutes) and lateral approach group (179 minutes) in terms of surgical time (P < 0.001).

Conclusions

The frequency of superficial and deep periprosthetic infections during the first postoperative year was not significantly different in the lateral approach group compared to the anterior approach group, despite the significantly longer surgical time in the lateral transfibular approach group.  相似文献   
77.
78.
We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ?=?0.903 (p < 0.0001), sensitivity?=?91% and specificity?=?100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease.  相似文献   
79.
80.
The aim of our study was to investigate the impact of the epsilon phenotype in brain glucose consumption in a population with Alzheimer’s disease. Statistical Parametric Mapping (SPM8) was used to investigate differences in brain glucose consumption (as detectable by means of 18F FDG-PET/CT) in the population examined. A total of 129 patients (72 females and 57 males) with a diagnosis of probable AD according to the NINCDS-ADRDA criteria underwent the PET/CT examination. The mean (SD) age of the patients was 70 (± 7) years; the mean Mini-Mental State Examination was 19(± 5.6). 59 expressed epsilon 4 phenotype (E4) and 70 expressed the epsilon 3 phenotype (E3). Cerebral spinal fluid amyloid, tau, and t-tau have been measured resulting equal to 367.4 (± 149.1), 584.7 (± 312.1), and 79.2(± 45.9) pg/ml, respectively. Patients with confirmed amyloid and Tau changes were classified as AD. Patients with amyloid changes but negative Tau, considered as high risk of AD, were classified as IAD. Age, sex, MMSE, scholarship, and CSF parameters were used as a covariate in the SPM analyses. We did not find significant differences in age, gender, and MMSE and CSF parameters among groups. In the analysis of the AD group as compared to AD-E3, AD-E4 subjects show a significant reduction of brain glucose consumption in inferior frontal gyrus bilaterally (BA 45, BA 47). In the analysis of the IAD group as compared to IAD-E3, IAD-E4 subjects show a significant reduction of brain glucose consumption in right in medial, middle, and superior frontal gyrus (BA10, BA11), and in left medial and middle frontal gyrus (BA10, BA11). The differences between IAD-E3 and AD-E3 and between IAD-E4 and AD-E4 (and vice versa analysis) resulted not significant. APO-e4 is related to a major involvement of the frontal cortex confirming its role of risk factor in AD, while APO-3 seems not related to a specific pattern, supporting the hypothesis of neutral/protective role in AD.  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