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   640篇
  免费   73篇
  国内免费   3篇
耳鼻咽喉   5篇
儿科学   10篇
妇产科学   11篇
基础医学   107篇
口腔科学   24篇
临床医学   69篇
内科学   121篇
皮肤病学   45篇
神经病学   34篇
特种医学   15篇
外科学   77篇
综合类   3篇
预防医学   44篇
眼科学   31篇
药学   53篇
中国医学   3篇
肿瘤学   64篇
  2024年   1篇
  2023年   14篇
  2022年   25篇
  2021年   54篇
  2020年   40篇
  2019年   49篇
  2018年   47篇
  2017年   41篇
  2016年   41篇
  2015年   36篇
  2014年   40篇
  2013年   42篇
  2012年   60篇
  2011年   62篇
  2010年   27篇
  2009年   22篇
  2008年   19篇
  2007年   28篇
  2006年   18篇
  2005年   13篇
  2004年   6篇
  2003年   7篇
  2002年   9篇
  2001年   2篇
  1999年   2篇
  1994年   1篇
  1992年   2篇
  1991年   1篇
  1989年   2篇
  1974年   2篇
  1971年   1篇
  1969年   1篇
  1968年   1篇
排序方式: 共有716条查询结果,搜索用时 359 毫秒
91.
92.
93.

Background

Physical activity is inversely associated with the risk of breast cancer among women in the general population. It is not clear whether or not physical activity is associated with the risk of BRCA-associated breast cancer.

Methods

We conducted a case–control study of 443 matched pairs of BRCA mutation carriers to evaluate the association between physical activity and breast cancer risk. Moderate and vigorous physical activities at ages 12–13, ages 14–17, ages 18–22, ages 23–29 and ages 30–34 were determined using the Nurses’ Health Study II Physical Activity Questionnaire. We estimated mean metabolic equivalent task hours/week for moderate, vigorous and total physical activities overall (ages 12–34), during adolescence (ages 12–17) and during early adulthood (ages 18–34). Logistic regression analysis was used to estimate the odds ratios (OR) and 95% confidence intervals (CI) for total, moderate and strenuous recreational physical activities and breast cancer risk, by menopausal status.

Results

Overall, there was no significant association between total physical activity and subsequent breast cancer risk (ORQ4 vs. Q1 = 1.01, 95% CI 0.69–1.47; P-trend = 0.72). Moderate physical activity between ages 12–17 was associated with a 38% decreased risk of premenopausal breast cancer (ORQ4 vs. Q1 = 0.62; 95% CI 0.40–0.96; P-trend = 0.01). We found no association between exercise and breast cancer diagnosed after menopause.

Conclusions

These findings suggest that early-life physical activity is associated with a reduced risk of premenopausal breast cancer among BRCA mutation carriers.

Impact

Future prospective analyses, complemented by mechanistic evidence, are warranted in this high-risk population.
  相似文献   
94.
Tumor cells are able to attract mesenchymal stem cells (MSCs) to primary tumor site. On the other hand, MSCs secrete various factors to attract tumor cells towards BM. In this review, in addition to assessment of MSCs function at tumor sites and their impact on growth and metastasis of tumor cells, the importance of MSC in attraction of malignant cells to BM and their involvement in drug resistance of tumor cells have also been studied. Relevant literature was identified by a PubMed search (2000–2015) of English-language literature using the terms mesenchymal stem cells, cancer cell, metastasis, and tumor microenvironment. MSCs migrate towards tumor microenvironment and are involved in both pro-tumorigenic and antitumorigenic functions. The dual function of MSCs at tumor sites is dependent upon a variety of factors, including the type and origin of MSCs, the cancer cell line under study, in vivo or in vitro conditions, the factors secreted by MSCs and interactions between MSCs, host immune cells and cancer cells. Therefore, MSCs can be regarded both as friends and enemies of cancer cells. Although the role of a number of pathways, including IL-6/STAT3 pathway, has been indicated in controlling the interaction between MSCs and tumor cells, other mechanisms by which MSCs can control the tumor cells are not clear yet. A better understanding of these mechanisms through further studies can determine the exact role of MSCs in cancer progression and identify them as important therapeutic agents or targets.  相似文献   
95.
96.
97.
Congenital fusion of the mandible and maxilla is a rare anomaly usually seen in association with various syndromes. Reports of isolated cases of bony fusion of the jaws are sparse. Only 10 reported cases were found in the literature search. Maxillomandibular fusion restricts mouth opening, causing feeding problems and difficulties in swallowing, respiration, growth, and development, and thus must be treated early. We report a case of congenital fusion of the mandible and maxilla in a 1-year-old boy and describe the clinical features of this anomaly to add to the existing literature on the subject. This is our second encounter of such a case.  相似文献   
98.
99.
Our objective is to clarify relationship between reversible cerebral vasoconstriction syndrome and administrating etanercept during puerperium. Several lines of evidence have suggested tumor necrosis factor (TNF) as a mediator of vascular dysfunction associated with estrogen deficiency. A 32-year-old woman resumed etanercept (25 mg/week), a TNF inhibitor, which had been discontinued during pregnancy, because of the deterioration of rheumatoid arthritis. She was admitted to our hospital with upper right quadrant blindness and mild right hemiparesis accompanied by pulsating left occipital pain, which had appeared 4 hours after restarting etanercept (25 mg/week). Magnetic resonance imaging and angiography revealed acute left hippocampal infarction with multiple segmental stenoses of the main intracranial arteries. Reversible cerebral vasoconstriction syndrome was diagnosed based on improvement of the multiple stenoses on magnetic resonance angiography on hospital day 17. A causal relationship was considered to exist between TNF inhibition by etanercept and multiple cerebral vasoconstrictions with brain infarct in this puerperant.  相似文献   
100.
Children with severe hearing loss often struggle to communicate. Mothers of children with hearing loss may also suffer psychologically in their caregiving due to this communication barrier. Cochlear implant surgery improves child’s hearing sense, parent and children’s psychological well-being, and communication between children and their mothers. The aim of the present study is to compare happiness and self-esteem among the mothers of children with severe hearing loss before and after cochlear implantation. This cross sectional study was conducted with 40 mothers of children under the age of 7 with severe hearing loss, all of who were candidates for cochlear implant surgery in Imam Hospital, Ahvaz, Iran. A consecutive non-probabilistic sampling method was used. Mothers of children awaiting cochlear implantation completed the Oxford Happiness Questionnaire and Rosenberg Self-Esteem Inventory before and after their child’s surgery, in addition to a demographic information form. Paired t tests and Wilcoxon tests were used. A significant difference was observed between the happiness and self-esteem scores before and after surgery (p?<?0.001). Cochlear implantation surgery increases happiness and self-esteem in mothers of children with hearing loss. When a child with hearing loss goes through cochlear implant surgery, all family members will benefit from improved hearing in their child and thus, improved family communication overall.  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