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   45716篇
  免费   2331篇
  国内免费   230篇
耳鼻咽喉   539篇
儿科学   786篇
妇产科学   586篇
基础医学   5681篇
口腔科学   1256篇
临床医学   3098篇
内科学   10991篇
皮肤病学   965篇
神经病学   4012篇
特种医学   2347篇
外国民族医学   1篇
外科学   7514篇
综合类   201篇
一般理论   6篇
预防医学   1277篇
眼科学   851篇
药学   2988篇
  4篇
中国医学   109篇
肿瘤学   5065篇
  2023年   239篇
  2022年   404篇
  2021年   877篇
  2020年   486篇
  2019年   619篇
  2018年   806篇
  2017年   687篇
  2016年   869篇
  2015年   858篇
  2014年   1104篇
  2013年   1302篇
  2012年   2197篇
  2011年   2317篇
  2010年   1355篇
  2009年   1191篇
  2008年   2052篇
  2007年   2443篇
  2006年   2239篇
  2005年   2214篇
  2004年   2203篇
  2003年   2165篇
  2002年   2134篇
  2001年   1431篇
  2000年   1492篇
  1999年   1395篇
  1998年   652篇
  1997年   532篇
  1996年   484篇
  1995年   428篇
  1994年   383篇
  1993年   383篇
  1992年   1053篇
  1991年   888篇
  1990年   863篇
  1989年   840篇
  1988年   792篇
  1987年   783篇
  1986年   689篇
  1985年   634篇
  1984年   437篇
  1983年   360篇
  1982年   159篇
  1979年   304篇
  1978年   207篇
  1977年   183篇
  1974年   194篇
  1973年   166篇
  1972年   163篇
  1971年   183篇
  1969年   178篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
We report a case of a diaphragmatic hernia after a heart transplant operation. A 43-year-old woman, who underwent orthotropic heart transplantation for hypertrophic cadiomyopathy two year earlier, presented with vomiting and epigastric pain. A computed tomography scan showed that the stomach and transverse colon were dislocated in the left thoracic cavity. We diagnosed left diaphragmatic hernia incarceration and performed laparoscopic repair of the diaphragmatic hernia. A 12 × 8 cm diaphragmatic defect was found intraoperatively on the ventrolateral aspect of the left diaphragm, and the stomach with volvulus had herniated into the thorax through the defect. The hernia was considered to be iatrogenic. The diaphragmatic defect was large, and the diaphragm was thinning. We closed the defect by mesh repair. Laparoscopic mesh repair of the diaphragmatic hernia could be performed safely and with minimal invasiveness.  相似文献   
6.
7.
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   
8.
9.
Purpose: Orthodontic tooth movement occurs during the bone remodeling induced by therapeutic mechanical strain. It is important to investigate the relation between the strength of mechanical stress and bone formation activity. The aim of this study was to determine the effect of high-magnitude mechanical strain on bone formation in detail.

Materials and methods: Osteoblast-like cells isolated from fetal rat calvariae were loaded with 18% cyclic tension force (TF) for 48?h. To phenotypically investigate the effect of TF, we measured the number and the size of bone nodules stained by von Kossa technique on day 21 after cell seeding and determined the calcium content of bone nodules on day 14. Furthermore, we examined the gene expression of BMP-2, Runx2 and Msx2, which are important factors for bone nodule formation, on days 1, 4 and 7 after TF loading.

Results: The maximum bone nodule size in the control group was 1620 and 719?μm in the TF group. Furthermore, the mean number of bone nodules sized over 360?μm in the TF group was significantly decreased compared to the control group. The calcium content was also significantly decreased to 42% by TF loading. The mRNA expression of BMP-2, Runx2 and Msx2 was decreased 1 and 4 days after TF loading.

Conclusion: The differentiation of bone forming progenitor cells into bone nodule forming cells was inhibited by TF due to the decreased expression of bone formation related factors such as BMP-2, Runx2 and Msx2.  相似文献   
10.
The development of new treatments for metabolic syndrome is urgent project for decreasing the prevalence of coronary heart disease and diabetes mellitus in the advanced countries. Peroxisome proliferator-activated receptor (PPAR)alpha and gamma agonists have shed light on the treatment of hypertriglyceridemia and type 2 diabetes mellitus, respectively. Among PPARs, analysis of the PPARdelta functions is lagging behind because specific PPARdelta agonists have not been developed. The appearance of new PPARdelta agonists is brightening the prospects for elucidating the physiological role of PPARdelta. PPARdelta is a new target for the treatment of metabolic syndrome. In particular, the fact that fatty acid oxidation and energy dissipation in skeletal muscle and adipose tissue by PPARdelta agonists lead to improved lipid profile, reduced adiposity and insulin sensitivity is a breakthrough. It seems that treatment of PPARdelta agonists operate similarly to the caloric restriction and prolonged exercise. We suggest that the physiological role of PPARdelta may be an indicator for switching from glucose metabolism to fatty acid metabolism. To receive new benefits of PPARdelta agonists against metabolic syndrome by increasing fatty acid consumption in skeletal muscle and adipose tissue, we need to unveil more details on the functions of PPARdelta itself and its agonists in the future.  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