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   1365906篇
  免费   105260篇
  国内免费   6555篇
耳鼻咽喉   17070篇
儿科学   44059篇
妇产科学   36714篇
基础医学   201291篇
口腔科学   36582篇
临床医学   133883篇
内科学   262805篇
皮肤病学   26674篇
神经病学   113097篇
特种医学   49287篇
外国民族医学   381篇
外科学   187447篇
综合类   34736篇
现状与发展   8篇
一般理论   462篇
预防医学   116605篇
眼科学   29966篇
药学   102565篇
  28篇
中国医学   5245篇
肿瘤学   78816篇
  2021年   12747篇
  2019年   12770篇
  2018年   17518篇
  2017年   13457篇
  2016年   14303篇
  2015年   16832篇
  2014年   22850篇
  2013年   33940篇
  2012年   46861篇
  2011年   49678篇
  2010年   28993篇
  2009年   26472篇
  2008年   44588篇
  2007年   46793篇
  2006年   46864篇
  2005年   44949篇
  2004年   42602篇
  2003年   40395篇
  2002年   39071篇
  2001年   61452篇
  2000年   63113篇
  1999年   52855篇
  1998年   14974篇
  1997年   13660篇
  1996年   13453篇
  1995年   12785篇
  1994年   11920篇
  1993年   11089篇
  1992年   41746篇
  1991年   40905篇
  1990年   39554篇
  1989年   37434篇
  1988年   34685篇
  1987年   33784篇
  1986年   32226篇
  1985年   30693篇
  1984年   23057篇
  1983年   19606篇
  1982年   11758篇
  1979年   20813篇
  1978年   14816篇
  1977年   12064篇
  1976年   11877篇
  1975年   12111篇
  1974年   14800篇
  1973年   14472篇
  1972年   13357篇
  1971年   12418篇
  1970年   11485篇
  1969年   10410篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
113.
114.
115.
116.
117.

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   
118.
119.
120.
PurposeOur purpose was to determine the effect of chemoradiotherapy (CRT) on patient-reported quality of life (QOL) for patients with intact pancreas cancer.Methods and MaterialsWe reviewed a prospective QOL registry for patients with intact, clinically localized pancreatic ductal adenocarcinoma treated with CRT between June 2015 and November 2018. QOL was assessed pre-CRT (immediately before CRT, after neoadjuvant chemotherapy) and at the completion of CRT with the Functional Assessment of Cancer Therapy-Hepatobiliary (FACT-Hep) and its component parts: FACT-General (FACT-G) and hepatobiliary cancer subscore (HCS). A minimally important difference from pre-CRT was defined as ≥ 6, 5, and 8 points for FACT-G, HCS, and FACT-Hep, respectively.ResultsOf 157 patients who underwent CRT, 100 completed both pre- and post-CRT surveys and were included in the primary analysis. Median age at diagnosis was 65 years (range, 23-90). National Comprehensive Cancer Network resectability status was resectable (3%), borderline resectable (40%), or locally advanced (57%). Folinic acid, 5-fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX) (75%) or gemcitabine and nab-paclitaxel (42%) were given for a median of 6 cycles (range, 0-42) before CRT. Radiation therapy techniques included 3-dimensional conformal (22%), intensity modulated photon (55%), and intensity modulated proton (23%) radiation therapy to a median dose of 50 Gy (range, 36-62.5). Concurrent chemotherapy was most commonly capecitabine (82%). Sixty-three patients (63%) had surgery after CRT. The mean decline in FACT-G, HCS subscale, and FACT-Hep from pre- to post-CRT was 3.5 (standard deviation [SD], 13.7), 1.7 (SD 7.8), and 5.2 (SD 19.4), respectively. Each of these changes were statistically significant, but did not meet the minimally important difference threshold. Pancreatic head tumor location was associated with decline in FACT-Hep. Nausea was the toxicity with the greatest increase from pre- to post-CRT by both physician-assessment and patient-reported QOL.ConclusionsFor patients with intact pancreatic adenocarcinoma, modern CRT is well tolerated with minimal decline in QOL during treatment.  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