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   41741篇
  免费   2753篇
  国内免费   429篇
耳鼻咽喉   837篇
儿科学   629篇
妇产科学   601篇
基础医学   6961篇
口腔科学   710篇
临床医学   3461篇
内科学   8018篇
皮肤病学   1359篇
神经病学   3264篇
特种医学   2306篇
外科学   5982篇
综合类   215篇
现状与发展   1篇
一般理论   7篇
预防医学   1614篇
眼科学   1072篇
药学   3621篇
中国医学   537篇
肿瘤学   3728篇
  2023年   223篇
  2022年   641篇
  2021年   1474篇
  2020年   746篇
  2019年   1085篇
  2018年   1326篇
  2017年   993篇
  2016年   1467篇
  2015年   1966篇
  2014年   2258篇
  2013年   2628篇
  2012年   3823篇
  2011年   3654篇
  2010年   2185篇
  2009年   1746篇
  2008年   2611篇
  2007年   2427篇
  2006年   2222篇
  2005年   2001篇
  2004年   1666篇
  2003年   1431篇
  2002年   1295篇
  2001年   753篇
  2000年   676篇
  1999年   541篇
  1998年   258篇
  1997年   206篇
  1996年   186篇
  1995年   158篇
  1994年   130篇
  1993年   110篇
  1992年   203篇
  1991年   214篇
  1990年   179篇
  1989年   151篇
  1988年   154篇
  1987年   173篇
  1986年   122篇
  1985年   123篇
  1984年   76篇
  1983年   79篇
  1982年   53篇
  1981年   40篇
  1980年   39篇
  1979年   61篇
  1978年   53篇
  1976年   30篇
  1975年   30篇
  1974年   27篇
  1971年   24篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Direct peroral cholangioscopy (POC) using an ultra‐slim upper endoscope is one modality of POC for intraductal endoscopic evaluation and treatment of the bile duct. Choledochoduodenostomy (CDS) is one modality of biliary bypass surgery that provides a new route to the bile duct. We carried out direct POC using an ultra‐slim upper endoscope without the use of accessories in 10 patients (four sump syndromes, three bile duct strictures and three intrahepatic duct stones) previously undergoing surgical CDS. Direct POC was successful in all patients. The use of an intraductal balloon catheter was required in one patient for advancement of the endoscope into the bile duct. Distal bile ducts with sump syndromes were cleared using baskets and water irrigation under direct POC. Cholangiocarcinoma was diagnosed in one patient with hilar bile duct stricture after cholangioscopic evaluation and a targeting forceps biopsy under direct POC. Intrahepatic duct stones were successfully extracted after intraductal fragmentation under direct POC. Oozing bleeding occurred during intraductal lithotripsy but stopped spontaneously. Direct POC using an ultra‐slim upper endoscope without the assistance of accessories can easily be carried out in patients undergoing CDS.  相似文献   
3.
4.
5.
Sonodynamic therapy (SDT) consists of the synergetic interaction between ultrasound and a chemical agent. In SDT, the cytotoxicity is triggered by ultrasonic stimuli, notably through cavitation. The unique features of SDT are relevant in the clinical context more than ever: the need for efficacy, accuracy, and safety while being noninvasive and preserving the patient's quality of life. However, despite the promising results of this technique, only a few clinical reports describe the use of SDT. The objective of this article is to provide an extensive overview of the clinical and preclinical research conducted in vivo on SDT, to identify the limitations, and to detail the developed strategies to overcome them.  相似文献   
6.
7.
ObjectiveTo compare the lumen parameters measured by the location-adaptive threshold method (LATM), in which the inter- and intra-scan attenuation variabilities of coronary computed tomographic angiography (CCTA) were corrected, and the scan-adaptive threshold method (SATM), in which only the inter-scan variability was corrected, with the reference standard measurement by intravascular ultrasonography (IVUS).Materials and MethodsThe Hounsfield unit (HU) values of whole voxels and the centerline in each of the cross-sections of the 22 target coronary artery segments were obtained from 15 patients between March 2009 and June 2010, in addition to the corresponding voxel size. Lumen volume was calculated mathematically as the voxel volume multiplied by the number of voxels with HU within a given range, defined as the lumen for each method, and compared with the IVUS-derived reference standard. Subgroup analysis of the lumen area was performed to investigate the effect of lumen size on the studied methods. Bland-Altman plots were used to evaluate the agreement between the measurements.ResultsLumen volumes measured by SATM was significantly smaller than that measured by IVUS (mean difference, 14.6 mm3; 95% confidence interval [CI], 4.9–24.3 mm3); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, −0.7 mm3; 95% CI, −9.1–7.7 mm3). The lumen area measured by SATM was significantly smaller than that measured by LATM in the smaller lumen area group (mean of difference, 1.07 mm2; 95% CI, 0.89–1.25 mm2) but not in the larger lumen area group (mean of difference, −0.07 mm2; 95% CI, −0.22–0.08 mm2). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 mm2; 95% CI, 0.27–0.65 mm2) than in that of IVUS and SATM (1.53 mm2; 95% CI, 1.27–1.79 mm2).ConclusionSATM underestimated the lumen parameters for computed lumen segmentation in CCTA, and this may be overcome by using LATM.  相似文献   
8.
9.
10.
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