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   3890篇
  免费   306篇
  国内免费   19篇
耳鼻咽喉   21篇
儿科学   182篇
妇产科学   125篇
基础医学   421篇
口腔科学   95篇
临床医学   387篇
内科学   938篇
皮肤病学   59篇
神经病学   281篇
特种医学   190篇
外国民族医学   1篇
外科学   470篇
综合类   97篇
一般理论   1篇
预防医学   414篇
眼科学   14篇
药学   214篇
中国医学   3篇
肿瘤学   302篇
  2021年   50篇
  2020年   36篇
  2019年   59篇
  2018年   57篇
  2017年   48篇
  2016年   50篇
  2015年   50篇
  2014年   99篇
  2013年   132篇
  2012年   182篇
  2011年   169篇
  2010年   136篇
  2009年   110篇
  2008年   142篇
  2007年   198篇
  2006年   188篇
  2005年   175篇
  2004年   147篇
  2003年   145篇
  2002年   116篇
  2001年   103篇
  2000年   129篇
  1999年   107篇
  1998年   77篇
  1997年   64篇
  1996年   63篇
  1995年   47篇
  1994年   50篇
  1993年   40篇
  1992年   78篇
  1991年   77篇
  1990年   59篇
  1989年   65篇
  1988年   75篇
  1987年   56篇
  1986年   52篇
  1985年   39篇
  1984年   53篇
  1983年   36篇
  1981年   31篇
  1980年   44篇
  1978年   42篇
  1977年   34篇
  1974年   44篇
  1972年   32篇
  1970年   49篇
  1969年   33篇
  1968年   34篇
  1967年   31篇
  1966年   35篇
排序方式: 共有4215条查询结果,搜索用时 13 毫秒
81.
82.

Purpose

There is no consensus on what constitutes adequate negative margins in breast-conserving therapy (BCT). We systematically review the evidence on surgical margins in BCT for invasive breast cancer to support the development of clinical guidelines.

Methods

Study-level meta-analysis of studies reporting local recurrence (LR) data relative to final microscopic margin status and the threshold distance for negative margins. LR proportion was modeled using random-effects logistic meta-regression.

Results

Based on 33 studies (LR in 1,506 of 28,162), the odds of LR were associated with margin status [model 1: odds ratio (OR) 1.96 for positive/close vs negative; model 2: OR 1.74 for close vs. negative, 2.44 for positive vs. negative; (P < 0.001 both models)] but not with margin distance [model 1: >0 mm vs. 1 mm (referent) vs. 2 mm vs. 5 mm (P = 0.12); and model 2: 1 mm (referent) vs. 2 mm vs. 5 mm (P = 0.90)], adjusting for study median follow-up time. There was little to no statistical evidence that the odds of LR decreased as the distance for declaring negative margins increased, adjusting for follow-up time [model 1: 1 mm (OR 1.0, referent), 2 mm (OR 0.95), 5 mm (OR 0.65), P = 0.21 for trend; and model 2: 1 mm (OR 1.0, referent), 2 mm (OR 0.91), 5 mm (OR 0.77), P = 0.58 for trend]. Adjustment for covariates, such as use of endocrine therapy or median-year of recruitment, did not change the findings.

Conclusions

Meta-analysis confirms that negative margins reduce the odds of LR; however, increasing the distance for defining negative margins is not significantly associated with reduced odds of LR, allowing for follow-up time. Adoption of wider relative to narrower margin widths to declare negative margins is unlikely to have a substantial additional benefit for long-term local control in BCT.  相似文献   
83.

Background

For breast-conserving surgery, the method of margin assessment that most frequently achieves negative margins without increasing the volume of tissue excised is uncertain. We examined our institutional experience with three different margin assessment methods used by six experienced breast surgeons.

Methods

Patients undergoing breast-conserving surgery for invasive carcinoma during July to December of a representative year during which each method was performed (perpendicular, 2003; tangential, 2004; cavity shave, 2011) were included. The effect of margin method on the positive margin rate at first excision and the total volume excised to achieve negative margins were evaluated by multivariable analysis, by surgeon, and by tumor size and presence of extensive intraductal component (EIC).

Results

A total of 555 patients were identified, as follows: perpendicular, 140; tangential, 124; and cavity shave, 291. The tangential method had a higher rate of positive margins at first excision than the perpendicular and cavity-shave methods (49, 15, 11 %, respectively; p < 0.0001). Median volumes to achieve negative margins were similar (55 ml perpendicular; 64 ml tangential; 62 ml cavity shave; p = 0.24). Four of six surgeons had the lowest rate of positive margins with the cavity-shave method, which was significant when compared to the tangential method (p < 0.0001) but not the perpendicular method (p = 0.37). The volume excised by the three methods varied by surgeon (p < 0.0001). The perpendicular method was optimal for T1 tumors without EIC; the cavity-shave method tended to be superior for T2–T3 tumors and/or EIC.

Conclusions

Although the cavity-shave method may decrease the rates of positive margins, its effect on volume is variable among surgeons and may result in an increase in the total volume excised for some surgeons and for small tumors without EIC.  相似文献   
84.

Introduction

For women with ductal carcinoma in situ (DCIS) undergoing breast-conserving surgery (BCS), the benefit of magnetic resonance imaging (MRI) remains unknown. Here we examine the relationship of MRI and locoregional recurrence (LRR) and contralateral breast cancer (CBC) for DCIS treated with BCS, with and without radiotherapy (RT).

Methods

A total of 2,321 women underwent BCS for DCIS from 1997 to 2010. All underwent mammography, and 596 (26 %) also underwent perioperative MRI; 904 women (39 %) did not receive RT, and 1,391 (61 %) did. Median follow-up was 59 months, and 548 women were followed for ≥8 years. The relationship between MRI and LRR was examined using multivariable analysis.

Results

There were 184 LRR events; 5- and 8-year LRR rates were 8.5 and 14.6 % (MRI), respectively, and 7.2 and 10.2 % (no-MRI), respectively (p = 0.52). LRR was significantly associated with age, menopausal status, margin status, RT, and endocrine therapy. After controlling for these variables and family history, presentation, number of excisions, and time period of surgery, there remained no trend toward association of MRI and lower LRR [hazard ratio (HR) 1.18, 95 % confidence interval (CI) 0.79–1.78, p = 0.42]. Restriction of analysis to the no-RT subgroup showed no association of MRI with lower LRR rates (HR 1.36, 95 % CI 0.78–2.39, p = 0.28). No difference in 5- or 8-year rates of CBC was seen between the MRI (3.5 and 3.5 %) and no-MRI (3.5 and 5.1 %) groups (p = 0.86).

Conclusions

We observed no association between perioperative MRI and lower LRR or CBC rates in patients with DCIS, with or without RT. In the absence of evidence that MRI improves outcomes, the routine perioperative use of MRI for DCIS should be questioned.  相似文献   
85.
86.
87.
88.
89.
Clinical Rheumatology - Patients with rheumatoid arthritis (RA) often receive opioid analgesics for pain management. We examined the association between mental health conditions and the risk of...  相似文献   
90.
This study examined fathers' perceptions regarding their home-based activities (HBA) and the influence of fathers' demographic characteristics on their perceptions and practices at home. A total of 396 fathers completed a survey questionnaire describing their demographic information, perceptions and their practices regarding their involvement in HBA. Results indicated that fathers have moderate level of practice concerning their HBA, yet they have low perception of their actual practice at HBA. In addition, there was a statistical significance in HBA due to fathers' age, educational level and specialisation which had an influence on their perceptions as well. Recommendations and implications of future research were discussed.  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