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   176241篇
  免费   1052篇
  国内免费   5篇
耳鼻咽喉   1138篇
儿科学   6636篇
妇产科学   3042篇
基础医学   16573篇
口腔科学   1546篇
临床医学   12430篇
内科学   31015篇
皮肤病学   725篇
神经病学   16532篇
特种医学   8936篇
外科学   28875篇
综合类   2318篇
一般理论   5篇
预防医学   18218篇
眼科学   2743篇
药学   9587篇
中国医学   627篇
肿瘤学   16352篇
  2022年   24篇
  2021年   50篇
  2020年   30篇
  2019年   53篇
  2018年   21950篇
  2017年   17393篇
  2016年   19531篇
  2015年   911篇
  2014年   799篇
  2013年   799篇
  2012年   6997篇
  2011年   21032篇
  2010年   18819篇
  2009年   11526篇
  2008年   19522篇
  2007年   21711篇
  2006年   575篇
  2005年   2202篇
  2004年   3396篇
  2003年   4380篇
  2002年   2521篇
  2001年   349篇
  2000年   493篇
  1999年   246篇
  1998年   213篇
  1997年   207篇
  1996年   94篇
  1995年   107篇
  1994年   108篇
  1993年   58篇
  1992年   60篇
  1991年   99篇
  1990年   134篇
  1989年   87篇
  1988年   64篇
  1987年   52篇
  1986年   35篇
  1985年   31篇
  1984年   29篇
  1983年   29篇
  1982年   30篇
  1980年   43篇
  1970年   21篇
  1969年   24篇
  1938年   61篇
  1937年   25篇
  1935年   23篇
  1934年   30篇
  1932年   57篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Breast-conserving therapy, which includes wide local excision of the tumor followed by irradiation, has become a standard treatment option for women with early-stage invasive breast cancer. The potential advantages of conservative breast surgery include the minor outpatient nature of the procedures, lower incidence of post-operative pain and complications, preservation of the breast and nipple areolar complex, and shorter delay to adjuvant therapy. However, not all patients are optimal candidates for breast-conserving procedures. Oncoplastic techniques combine the removal of breast cancer tumors in combination with either local volume replacement techniques to correct small defects, or by immediate reconstruction of larger defects using techniques of plastic surgery with or without contralateral breast procedures for symmetry. Therefore, oncoplastic techniques offer the potential to perform a wider excision of the tumor with an improved cosmetic result, thus potentially increasing the eligible pool for breast conservation.  相似文献   
992.
993.
994.
995.
Abdominal pain is one of the common symptoms reported by children in urgent care clinics. While most children tend to have self-limiting conditions, the treating pediatrician should watch out for underlying serious causes like intestinal obstruction and perforation peritonitis, which require immediate referral to an emergency department (ED). Abdominal pain may be secondary to surgical or non-surgical causes, and will differ as per the age of the child. The common etiologies for abdominal pain presenting to an urgent care clinic are acute gastro-enteritis, constipation and functional abdominal pain; however, a variety of extra-abdominal conditions may also present as abdominal pain. Meticulous history taking and physical examination are the best tools for diagnosis, while investigations have a limited role in treating benign etiologies.  相似文献   
996.
A peripherally inserted central catheter (PICC) is a thin catheter that is inserted via arm veins and threaded near the heart, providing intravenous access. The final catheter tip position is always confirmed on a chest radiograph (CXR) immediately after insertion since malpositioned PICCs can cause potentially life-threatening complications. Although radiologists interpret PICC tip location with high accuracy, delays in interpretation can be significant. In this study, we proposed a fully-automated, deep-learning system with a cascading segmentation AI system containing two fully convolutional neural networks for detecting a PICC line and its tip location. A preprocessing module performed image quality and dimension normalization, and a post-processing module found the PICC tip accurately by pruning false positives. Our best model, trained on 400 training cases and selectively tuned on 50 validation cases, obtained absolute distances from ground truth with a mean of 3.10 mm, a standard deviation of 2.03 mm, and a root mean squares error (RMSE) of 3.71 mm on 150 held-out test cases. This system could help speed confirmation of PICC position and further be generalized to include other types of vascular access and therapeutic support devices.  相似文献   
997.
Cardiac hemangiomas are rare benign tumors. Here, we report the case of a man in his 30s who had a cardiac hemangioma with no symptoms. He was being treated with β-blockers for chronic heart failure with hypertensive heart disease at Osaka Minato Central Hospital. Routine echocardiography revealed a mobile spherical mass in the left ventricle that had not been detected on echocardiography performed 4 months previously. Subsequently, the tumor was excised to prevent potential embolic events and was pathologically diagnosed as a cardiac hemangioma. This case demonstrates the relatively rapid progress of a cardiac hemangioma regardless of β-blocker administration, which is occasionally used for the treatment of hemangiomas. The efficacy of β-blockers in treating cardiac hemangiomas may vary according to the type of β-blocker. Echocardiography is useful in screening and follow-up of cardiac hemangiomas; however, additional imaging modalities are needed for differential diagnosis.  相似文献   
998.
The current study shows an advanced synesthetic technique of a nitrate-fertilizer with a controlled release behavior into different soils (normal and acidic agriculture soils solutions) at different climate temperatures. The environmentally friendly and the biocompatible layered double hydroxide (LDH) clay material was used as a host to accommodate the nitrate anion into its interlayer gallery by applying a reconstruction-incorporation technique (the memory effect property of LDH that allows calcined LDH to memorize its original structure). The prepared materials were characterized by different spectroscopic techniques including; X-ray powder spectroscopy, IR, SEM, TEM, and TGA analyses. A remarkable loading ratio of the nitrate anion fertilizer was recorded into the LDH structure. Around 90 wt% of the intercalated nitrate anion was released in a sustained controlled behavior over around 24 days, while the same amount of nitrate was released over 10 days in the acidic soil. Accordingly, the present study offers a new passway for the formulation of controlled release fertilizers by using the hosting anionic clay LDH materials.  相似文献   
999.
1000.
Real-time modelling of force interaction with soft tissues is of great importance for interactive surgical simulation. This paper presents a new ChainMail algorithm for real-time modelling of soft tissue deformation under force interaction. Unlike traditional ChainMails using a box-shaped bounding region, the proposed method defines an ellipsoid-shaped bounding region according to the concept of principal strains in continuum mechanics to control the movement of chain elements. Based on this ellipsoid-shaped bounding region, new position adjustment rules are developed and further integrated with temporal-domain model dynamics for dynamic simulation of soft tissue deformation. Haptic interaction with soft tissues is achieved via force input, soft tissue deformation, and force feedback. Experimental results demonstrate that the proposed ChainMail can simulate soft tissue mechanical behaviours, accommodate isotropic and homogeneous, anisotropic and heterogeneous materials, and handle large deformation. The proposed ChainMail also requires only small computational time, capable of achieving real-time computational performance.  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