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   1333315篇
  免费   102061篇
  国内免费   4253篇
耳鼻咽喉   16791篇
儿科学   43578篇
妇产科学   36395篇
基础医学   197873篇
口腔科学   35905篇
临床医学   129493篇
内科学   258029篇
皮肤病学   26472篇
神经病学   111878篇
特种医学   48179篇
外国民族医学   366篇
外科学   184099篇
综合类   28772篇
现状与发展   1篇
一般理论   461篇
预防医学   114181篇
眼科学   28968篇
药学   98830篇
  6篇
中国医学   3165篇
肿瘤学   76187篇
  2021年   10910篇
  2019年   11642篇
  2018年   16316篇
  2017年   12300篇
  2016年   13266篇
  2015年   15221篇
  2014年   20830篇
  2013年   32096篇
  2012年   44295篇
  2011年   46943篇
  2010年   27098篇
  2009年   24953篇
  2008年   42764篇
  2007年   45115篇
  2006年   45212篇
  2005年   43642篇
  2004年   41595篇
  2003年   39536篇
  2002年   38326篇
  2001年   60871篇
  2000年   62538篇
  1999年   52296篇
  1998年   14590篇
  1997年   13285篇
  1996年   13120篇
  1995年   12462篇
  1994年   11631篇
  1993年   10927篇
  1992年   41579篇
  1991年   40771篇
  1990年   39453篇
  1989年   37347篇
  1988年   34591篇
  1987年   33706篇
  1986年   32153篇
  1985年   30649篇
  1984年   23039篇
  1983年   19596篇
  1982年   11753篇
  1979年   20807篇
  1978年   14817篇
  1977年   12065篇
  1976年   11877篇
  1975年   12114篇
  1974年   14800篇
  1973年   14472篇
  1972年   13357篇
  1971年   12419篇
  1970年   11486篇
  1969年   10410篇
排序方式: 共有10000条查询结果,搜索用时 843 毫秒
111.
112.

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   
113.
114.
115.
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   
116.
117.
118.
119.
120.
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