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   451篇
  免费   48篇
  国内免费   18篇
耳鼻咽喉   2篇
儿科学   14篇
妇产科学   37篇
基础医学   64篇
口腔科学   11篇
临床医学   37篇
内科学   136篇
皮肤病学   6篇
神经病学   10篇
特种医学   77篇
外科学   47篇
综合类   5篇
预防医学   28篇
眼科学   2篇
药学   10篇
中国医学   2篇
肿瘤学   29篇
  2021年   3篇
  2020年   8篇
  2019年   5篇
  2018年   13篇
  2017年   8篇
  2016年   9篇
  2015年   8篇
  2014年   11篇
  2013年   19篇
  2012年   8篇
  2011年   19篇
  2010年   27篇
  2009年   22篇
  2008年   13篇
  2007年   33篇
  2006年   14篇
  2005年   13篇
  2004年   8篇
  2003年   16篇
  2002年   6篇
  2001年   8篇
  2000年   6篇
  1999年   8篇
  1998年   15篇
  1997年   15篇
  1996年   14篇
  1995年   13篇
  1994年   14篇
  1993年   18篇
  1992年   5篇
  1991年   3篇
  1990年   10篇
  1989年   20篇
  1988年   20篇
  1987年   18篇
  1986年   9篇
  1985年   10篇
  1984年   5篇
  1983年   11篇
  1982年   5篇
  1981年   4篇
  1980年   6篇
  1979年   2篇
  1978年   1篇
  1977年   7篇
  1976年   5篇
  1975年   2篇
排序方式: 共有517条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: To determine the prevalence and age of onset of common risky behaviors such as smoking and sexual activity in teens with cystic fibrosis and those with sickle cell disease and to compare their behaviors with those of adolescents in the general population. DESIGN: Survey. SETTING: All five major pediatric tertiary care centers in North Carolina (study participants with sickle cell disease or cystic fibrosis) and North Carolina public schools (comparison population). PARTICIPANTS: Three hundred twenty-one adolescents with cystic fibrosis or sickle cell disease aged 12 to 19 years (mean age, 15.6 years; 49% female). Demographically matched comparison teens for each group were selected from 2760 in-school adolescents (mean age, 16.0 years; 51% female). MAIN OUTCOMES MEASURES: Prevalence of tobacco and marijuana use, alcohol use, sexual intercourse, sexually transmitted diseases, seat belt use, weapon carrying, and age of onset of these behaviors. RESULTS: Chronically ill teens reported significantly less lifetime and current use of tobacco, marijuana, and alcohol; less sexual intercourse; less weapon carrying, less drunk driving, and more seat belt use than their peers. Nonetheless, 21% of the teens with cystic fibrosis and 30% of those with sickle cell disease had smoked; sexual intercourse was reported by 28% and 51%, respectively. Age of onset of these behaviors was frequently older for the chronically ill teens. CONCLUSION: Teens with cystic fibrosis or sickle cell disease took more potentially damaging health risks than might be expected, although the prevalence was lower than reported by their peers. Future longitudinal studies should examine the relationships between chronic illness, physical and psychosocial maturation, and risky behavior. Screening for psychosocial issues, including risky behaviors, should be incorporated into the routine health care of chronically ill teens.  相似文献   
102.
An increasing evidence base suggests that low bone mineral density (BMD) and fractures are associated with cardiovascular disease (CVD). We conducted a systematic review and meta‐analysis summarizing the evidence of low BMD and fractures as risk factors for future CVD. Two independent authors searched major databases from inception to August 1, 2016, for longitudinal studies reporting data on CVD incidence (overall and specific CVD) and BMD status and fractures. The association between low BMD, fractures, and CVD across longitudinal studies was explored by calculating pooled adjusted hazard ratios (HRs) ±95% confidence intervals (CIs) with a random‐effects meta‐analysis. Twenty‐eight studies (18 regarding BMD and 10 fractures) followed a total of 1,107,885 participants for a median of 5 years. Taking those with higher BMD as the reference, people with low BMD were at increased risk of developing CVD during follow‐up (11 studies; HR = 1.33; 95%CI, 1.27 to 1.38; I2 = 53%), after adjusting for a median of eight confounders. This finding was confirmed using a decrease in one standard deviation of baseline BMD (9 studies; HR = 1.16; 95% CI, 1.09 to 1.24; I2 = 69%). The presence of fractures at baseline was associated with an increased risk of developing CVD (HR = 1.20; 95% CI, 1.06 to 1.37; I2 = 91%). Regarding specific CVDs, low BMD was associated with an increased risk of developing coronary artery disease, cerebrovascular conditions, and CVD‐associated death. Fractures at baseline was associated with an increased risk of cerebrovascular conditions and death due to CVD. In conclusion, low BMD and fractures are associated with a small, but significant increased risk of CVD risk and possibly death. © 2017 American Society for Bone and Mineral Research.  相似文献   
103.
104.
Treatment of lipomas assisted with tumescent liposuction   总被引:1,自引:0,他引:1  
BACKGROUND: Lipoma is a common soft-tissue tumour of mature fat cells. Although surgical excision is effective, treatments that are less invasive and not associated with disfigurement of scar would be ideal for the treatment of lipomas. Recently, tumescent liposuction has been used for the treatment of lipomas. OBJECTIVE: To evaluate the efficacy of tumescent liposuction in lipoma treatment, we reviewed our experience of lipoma treatment by tumescent liposuction. METHODS: A total of 21 patients presenting with 31 lipomas were treated with tumescent liposuction. After liposuction, remaining stromas were removed by a haemostat through the small incision. Tumour size and post-operative complications were recorded before and after treatment. RESULTS: A total of 31 lipomas of 21 patients were treated by tumescent liposuction. The size of lipomas ranged between 1.2 and 11 cm (mean size, 4.1 cm). In 23 cases, there were no complications. However, remnant lipomas, bruise, haematoma and immediate dimpling were found as complications. CONCLUSION: Tumescent liposuctions with extracting remnant fat tissue and fibrous tissue through the opening for liposuction can be an effective treatment technique in lipoma treatment in the efficacy and cosmetic outcomes and this method can be a substitute for excision in treating large lipomas.  相似文献   
105.
106.
Duration of breastfeeding was studied in 556 women delivering at 2 maternity hospitals in Perth, Australia. At discharge 83.8% of women were breastfeeding their infants, including 6% who were giving complementary feeds. At 3 and 6 months, 61.8% and 49.9%, respectively, were still breastfeeding. In a Cox survival analysis of factors associated with duration of breastfeeding a positive association was found with maternal education, age and intended duration of breastfeeding. Male infants were more likely to be weaned before female infants and women whose partners were unemployed, or did not have a preference for breastfeeding, breastfed for shorter duration. There is still a need for programmes which support and encourage breastfeeding, focusing particularly on younger, less well-educated women who intend to breastfeed for less than the recommended 4-6 months.  相似文献   
107.
108.
A BamHI polymorphism has been identified in the human factor IX gene. This polymorphism, which occurs in approximately 6% of X chromosomes, has been used to determine the carrier status of a female in a family with a history of hemophilia B. This family was uninformative for the previously reported TaqI and Xmnl polymorphisms in the factor IX gene.  相似文献   
109.
110.
A newly recognized family of proteins that inhibit cyclin-dependent kinases (CDKs) termed cyclin-dependent kinase inhibitors (CDKI) have an important role in regulation of cell-cycle progression. A subfamily of these CDKIs (p15INK4B/MTS2, p16INK4/MTS1, and p18) have a high degree of structural and functional homology and are candidate tumor- suppressor genes. We evaluated the mutational status of the p15, p16, and p18 genes in 103 childhood acute lymphoblastic leukemia (ALL) samples and correlated these results with both their clinical data and additional results concerning their loss of heterozygosity in the region of the p15/p16 genes. Homozygous deletions of the p16 gene occurred extremely frequently in T-ALLs (17/22; 77%), and it was also frequent in precursor-B ALLs (12/81; 15%). Homozygous deletions of the p15 gene were also very frequent in T-ALLs (9/22; 41%), and it occurred in 5 of 81 (6%) precursor-B ALL samples. No deletions of p18 was found in any of the 103 ALL samples. Also, no point mutations of the p15, p16, and p18 genes were detected. We correlated p15/p16 alterations at diagnosis with their clinical characteristics as compared with 2,927 other patients treated similarly. Those with p15/p16 alterations were older; had higher white blood cell counts, often with T-cell ALL phenotype; and more frequently had a mediastinal mass at presentation; but they had the same nonremission, relapse, and survival rates at 5 years as did those patients whose blast cells did not have a p15/p16 deletion. To better understand the extent of alterations affecting chromosome 9p21 (location of the p15/p16 genes), loss of heterozygosity (LOH) was examined at D9S171, which is about 1 megabase proximal to the p15/p16 genes. LOH was detected in 15 of 37 (41%) informative samples. Interestingly, of the 24 informative samples that had no detectable alteration of the p15/p16 genes, 7 samples (29%) had LOH at D9S171. In summary, we show in a very large study that p15 and p16, but not p18, CDKI genes are very frequently altered in ALL; those with p15/p16 alterations are more frequently older children, have higher white blood cells at presentation, and often have a T-cell ALL phenotype. The LOH analysis suggests that another tumor-suppressor gene important in ALL also is present on chromosome 9p21.  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