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   177046篇
  免费   1104篇
  国内免费   5篇
耳鼻咽喉   1141篇
儿科学   6719篇
妇产科学   3180篇
基础医学   16742篇
口腔科学   1603篇
临床医学   12500篇
内科学   31278篇
皮肤病学   693篇
神经病学   16680篇
特种医学   8942篇
外科学   28890篇
综合类   2316篇
一般理论   2篇
预防医学   18170篇
眼科学   2744篇
药学   9512篇
中国医学   626篇
肿瘤学   16417篇
  2023年   32篇
  2022年   46篇
  2021年   130篇
  2020年   51篇
  2019年   125篇
  2018年   22021篇
  2017年   17426篇
  2016年   19576篇
  2015年   953篇
  2014年   886篇
  2013年   883篇
  2012年   7095篇
  2011年   21108篇
  2010年   18862篇
  2009年   11565篇
  2008年   19576篇
  2007年   21752篇
  2006年   624篇
  2005年   2240篇
  2004年   3440篇
  2003年   4371篇
  2002年   2528篇
  2001年   271篇
  2000年   423篇
  1999年   167篇
  1998年   218篇
  1997年   215篇
  1996年   101篇
  1995年   104篇
  1994年   102篇
  1993年   75篇
  1992年   42篇
  1991年   97篇
  1990年   132篇
  1989年   85篇
  1988年   66篇
  1987年   50篇
  1986年   39篇
  1985年   38篇
  1984年   23篇
  1983年   32篇
  1982年   29篇
  1980年   44篇
  1974年   26篇
  1938年   60篇
  1937年   25篇
  1935年   23篇
  1934年   30篇
  1932年   57篇
  1930年   48篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
971.
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   
972.
973.
974.
975.
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   
976.
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   
977.
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   
978.
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   
979.
980.
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