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   2120209篇
  免费   160581篇
  国内免费   6371篇
耳鼻咽喉   27517篇
儿科学   71391篇
妇产科学   59267篇
基础医学   310803篇
口腔科学   58770篇
临床医学   201263篇
内科学   406273篇
皮肤病学   45126篇
神经病学   174031篇
特种医学   78714篇
外国民族医学   651篇
外科学   303057篇
综合类   48777篇
现状与发展   1篇
一般理论   813篇
预防医学   176735篇
眼科学   47976篇
药学   155673篇
  8篇
中国医学   4797篇
肿瘤学   115518篇
  2019年   17162篇
  2018年   24219篇
  2017年   18438篇
  2016年   20436篇
  2015年   23242篇
  2014年   31985篇
  2013年   49527篇
  2012年   66831篇
  2011年   71004篇
  2010年   41831篇
  2009年   38806篇
  2008年   65480篇
  2007年   69221篇
  2006年   69779篇
  2005年   67207篇
  2004年   64637篇
  2003年   61747篇
  2002年   59873篇
  2001年   95653篇
  2000年   98130篇
  1999年   82395篇
  1998年   23581篇
  1997年   21322篇
  1996年   21136篇
  1995年   20241篇
  1994年   18763篇
  1993年   17582篇
  1992年   65857篇
  1991年   64779篇
  1990年   62993篇
  1989年   60154篇
  1988年   55436篇
  1987年   54856篇
  1986年   51805篇
  1985年   49732篇
  1984年   37593篇
  1983年   31806篇
  1982年   19209篇
  1981年   17034篇
  1979年   34428篇
  1978年   24759篇
  1977年   20535篇
  1976年   19855篇
  1975年   20516篇
  1974年   24990篇
  1973年   24317篇
  1972年   22431篇
  1971年   20917篇
  1970年   19368篇
  1969年   17823篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
151.
152.
153.
154.
155.
156.
Contrast‐enhanced spectral mammography (CESM) has a number of uses including the work‐up of inconclusive findings on mammography, assessment of breast symptoms, cancer staging, evaluation of response to neoadjuvant chemotherapy and recently as an alternative to magnetic resonance imaging (MRI) in high‐risk screening. CESM can be swiftly incorporated into the workflow of busy breast clinics. We share our experiences with CESM at a large breast assessment centre in Western Australia.  相似文献   
157.

Purpose

This study aimed to investigate 3 planning target volume (PTV) margin expansions and determine the most appropriate volume to be used in bladder preservation therapy when using daily cone beam computed tomography (CBCT). We aimed to establish whether a smaller PTV expansion is feasible without risking geographical miss.

Methods and materials

The study included patients with bladder cancer who were treated with a hypofractionated course of radiation therapy delivered with intensity modulated radiation therapy. The clinical target volume (CTV) was the whole empty bladder, and the PTV consisted of a 1.5-cm margin around the bladder (PTV1.5 cm). Patients underwent daily CBCT imaging before treatment to assess the bladder volume and ensure accurate positioning. We investigated 2 additional smaller PTV margin expansions to determine the most appropriate volume to be used with CBCT as a daily image guided radiation therapy modality. These margins were created retrospectively on every CBCT. The first additional volume was a uniform PTV margin of the surrounding 1 cm (PTV1 cm). When considering that the majority of the internal bladder movement was due to the variation in filling that occurs in the superior and anterior directions, a second volume of an anisotropic PTV margin with a 1.5-cm superior/anterior and 1 cm in other directions (PTV1/1.5 cm) was created. We recorded the frequency and measured the volume of bladder falling out of each PTV based on the daily CBCT.

Results

For the purpose of this study, we considered an arbitrary 5 cm3 of CTV falling out of the designated PTV as a clinically significant volumetric miss. The frequency of such a miss when applying the uniform PTV1 cm was 1%. However, when applying the uniform PTV1.5 cm and anisotropic PTV1/1.5 cm margins, the frequency was 0.5% and 0.5%, respectively.

Conclusions

The anisotropic PTV expansion of 1.5 cm superiorly and anteriorly and 1 cm in all other directions around the bladder (CTV) provides a safe PTV approach when daily CBCT imaging is used to localize an empty bladder.  相似文献   
158.
Hypertrophic lichen planus (HLP) is a T‐cell‐mediated process typically presenting with hypertrophic or verrucous plaques on the lower limbs. We report the case of a 24‐year‐old woman with a history of HLP since age 3 years presenting with rapid malignant transformation of one lesion into a large squamous cell carcinoma (SCC). Subsequent examination revealed progressive, widespread metastatic involvement, and the patient ultimately died from her disease. SCC associated with HLP is rare, with a review of the literature revealing fewer than 50 cases. This case highlights the need to be aware of suspicious changes in HLP and to educate patients as to when to be reevaluated.  相似文献   
159.
160.
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