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   3706篇
  免费   257篇
  国内免费   51篇
耳鼻咽喉   16篇
儿科学   71篇
妇产科学   22篇
基础医学   694篇
口腔科学   59篇
临床医学   314篇
内科学   789篇
皮肤病学   301篇
神经病学   276篇
特种医学   99篇
外科学   440篇
综合类   10篇
一般理论   1篇
预防医学   134篇
眼科学   94篇
药学   357篇
中国医学   48篇
肿瘤学   289篇
  2024年   4篇
  2023年   21篇
  2022年   91篇
  2021年   131篇
  2020年   78篇
  2019年   96篇
  2018年   117篇
  2017年   107篇
  2016年   161篇
  2015年   206篇
  2014年   258篇
  2013年   294篇
  2012年   397篇
  2011年   357篇
  2010年   208篇
  2009年   173篇
  2008年   243篇
  2007年   196篇
  2006年   172篇
  2005年   151篇
  2004年   116篇
  2003年   99篇
  2002年   87篇
  2001年   34篇
  2000年   38篇
  1999年   21篇
  1998年   20篇
  1997年   13篇
  1996年   17篇
  1995年   8篇
  1994年   4篇
  1993年   5篇
  1992年   16篇
  1991年   11篇
  1990年   8篇
  1989年   11篇
  1988年   8篇
  1987年   12篇
  1986年   3篇
  1985年   5篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1974年   2篇
  1973年   4篇
  1971年   2篇
  1970年   1篇
  1968年   2篇
排序方式: 共有4014条查询结果,搜索用时 15 毫秒
91.

Background

This study investigated the effects of total knee arthroplasty (TKA) on bone mineral density (BMD) of the proximal femur in patients who underwent the procedure.

Methods

Forty-eight patients scheduled to undergo unilateral TKA because of primary knee osteoarthritis were included in this study, which was conducted at a medical center between October 2006 and October 2009. In these 48 patients, 96 hips were evaluated. Measurement of BMD was performed preoperatively and one month, three months, six months, and one year after unilateral TKA. Repeated measured analysis of variance and paired t-tests for comparison of two repeated samples were used to compare differences between time points (preoperation, one, three, six, and 12 months) and between the operative and nonoperative sides.

Results

Preoperatively, BMD of the femoral neck, trochanter, and total hip on the operative side were lower than on the nonoperative side; however, there was no statistical difference. BMD of both femoral neck areas was significantly lower than preoperative BMD at one month and three months after TKA. BMD of both trochanter areas was significantly lower than preoperative BMD at one month and three months after TKA. BMD of both total hips was significantly lower than preoperative BMD at three months after TKA. However, no statistical differences of changes in BMD were observed between the operative and nonoperative sides at each measurement time.

Conclusions

According to our results, TKA was found to affect both proximal femurs during the acute period. However, TKA did not affect a change in BMD of the proximal femur during one year postoperative.  相似文献   
92.
Objectives. We evaluated a Social Branding antitobacco intervention for “hipster” young adults that was implemented between 2008 and 2011 in San Diego, California.Methods. We conducted repeated cross-sectional surveys of random samples of young adults going to bars at baseline and over a 3-year follow-up. We used multinomial logistic regression to evaluate changes in daily smoking, nondaily smoking, and binge drinking, controlling for demographic characteristics, alcohol use, advertising receptivity, trend sensitivity, and tobacco-related attitudes.Results. During the intervention, current (past 30 day) smoking decreased from 57% (baseline) to 48% (at follow-up 3; P = .002), and daily smoking decreased from 22% to 15% (P < .001). There were significant interactions between hipster affiliation and alcohol use on smoking. Among hipster binge drinkers, the odds of daily smoking (odds ratio [OR] = 0.44; 95% confidence interval [CI] = 0.30, 0.63) and nondaily smoking (OR = 0.57; 95% CI = 0.42, 0.77) decreased significantly at follow-up 3. Binge drinking also decreased significantly at follow-up 3 (OR = 0.64; 95% CI = 0.53, 0.78).Conclusions. Social Branding campaigns are a promising strategy to decrease smoking in young adult bar patrons.Tobacco companies1 and public health authorities2–5 recognize young adulthood as a critical time when experimenters either quit or transition to regular tobacco use. Young adults are also aspirational role models for youths.1,6,7 Tobacco companies devote considerable resources to reaching young adults to encourage tobacco use,1,8–11 and young adults have a high prevalence of smoking.12 In California in 2011, young adults had the highest smoking prevalence of any age group, and the Department of Health estimated that 32% of California smokers started smoking between the ages of 18 and 26 years.13 Although they are more likely to intend to quit and successfully quit than older adults,14–17 young adults are less likely to receive assistance with smoking cessation.18,19 Although there are few proven interventions to discourage young adult smoking,20 cessation before age 30 years avoids virtually all of the long-term adverse health effects of smoking.21Tobacco companies have a long history of using bars and nightclubs to reach young adults and to encourage smoking.1,6,9–11,22–24 Bar attendance and exposure to tobacco bar marketing is strongly associated with smoking.25 The 1998 Master Settlement Agreement and Food and Drug Administration regulations that limit tobacco advertising to youths, explicitly permit tobacco marketing in “adult only” venues, including bars and nightclubs.26,27Aggressive tobacco marketing may actually be more intensive in smoke-free bars: a 2010 study of college students attending bars found that students in the community with a smoke-free bar law were more likely to be approached by tobacco marketers, offered free gifts, and to take free gifts for themselves than in communities without a smoke-free bar law.28 Bars and nightclubs also attract young adults who are more likely to exhibit personality traits such as sensation seeking,29 increasing their risk30 independently of receptivity to tobacco advertising; tobacco promotional messages resonate with these personality traits.8,31 Tobacco marketing campaigns are tailored to specific segments of the population defined by psychographics (e.g., values, attitudes, shared interests, such as tastes in music and fashion, and friend groups) and demographic criteria, and they aim to create positive smoker images, identities, and social norms for smoking.1,8 Tobacco marketing campaigns also focus on young adult trendsetters to leverage peer influence to promote smoking.6,10In contrast to the tobacco companies’ efforts, most young adult health interventions take place in colleges or health centers rather than social environments.32–39 Bars and nightclub venues represent an opportunity to reach those at highest risk for long-term smoking morbidity and mortality.40 We evaluated the effectiveness of an intervention to decrease cigarette smoking by countering tobacco industry marketing strategies targeting young adults attending bars and nightclubs in the San Diego, California, “hipster” scene. Because tobacco and alcohol use are strongly linked,41,42 we also examined the effects of the intervention on alcohol use and among binge drinkers. We found a significant decrease in smoking in the community where the intervention took place, including significant decreases among nondaily smokers and binge drinkers, as well as a significant decrease in binge drinking.  相似文献   
93.
A possible negative effect of iron overload on bone metabolism has been suggested by the fact that patients with hemochromatosis, thalassemia, and sickle cell anemia have lower bone mineral density than the general population. However, the influence of iron overload on bone health in the general population is uncertain. The aim of this study was to investigate the relationship between serum ferritin levels and bone mineral density (BMD) in elderly Koreans. A total of 2,943 subjects aged 65 years and over who participated in the 2008–2010 Korea National Health and Nutrition Examination Surveys were included in this study. Age, physical activity, current smoking status, alcohol consumption, education level, household income, and dietary assessment were surveyed by a face-to-face interview. BMD was measured at the lumbar spine and femur by dual-energy X-ray absorptiometry, and other biochemical markers, including serum ferritin, 25-hydroxyvitamin D3, serum alkaline phosphatase, and parathyroid hormone, were assayed. After adjusting for age and body mass index, we found an association between BMD of the total lumbar spine, total femur, and femur neck and levels of alkaline phosphatase, parathyroid hormone, vitamin D3, and daily intake of calcium and protein. Serum ferritin levels were positively associated with BMD of the total lumbar spine, total femur, and femur neck after adjusting for all covariates in men, but not in women. This study suggests a positive association between serum ferritin levels and BMD in elderly South Korean men without hematologic disorders. Further study is warranted to verify the effects of iron on bone metabolism.  相似文献   
94.

Background

Using the da Vinci® robotic system, surgeons can complete secure thyroidectomy without noticeable neck scarring. This study compared the surgical completeness of transaxillary robotic thyroidectomy (RT) with conventional open procedures (OT) in treating papillary thyroid carcinoma (PTC) patients.

Materials and methods

From April 2009 through February 2011, 94 PTC patients underwent total thyroidectomy with central compartment neck dissection (CCND) at Yonsei University College of Medicine. All patients received 1.1 GBq radioactive iodine (RAI) ablation, post-therapy whole-body scans (TxWBS), and diagnostic WBS (DxWBS) 1 year later. We prospectively compared patient clinicopathologic characteristics and surgical completeness between the two groups.

Results

Fifty-one patients underwent OT and 43 underwent RT. Mean age was significantly younger in the RT group. Tumor size, capsular-invasion frequency, multifocality, bilaterality, and central nodal metastasis were not different between the two groups. The number of retrieved nodes during CCND did not significantly differ between the groups. There was no significant difference between the OT and RT groups in stimulated thyroglobulin levels acquired during TxWBS and DxWBS. The RAI uptake ratios at TxWBS were significantly higher in the RT group compared with the OT group; however, follow-up DxWBS showed no difference in RAI uptake ratios. Also, the ablation success rate was similar between the two groups. There were no abnormal findings in follow-up neck ultrasonography in either group.

Conclusion

Remnant thyroid tissue ablation after transaxillary RT was successfully managed by 1.1 GBq RAI. RT showed similar surgical completeness versus conventional OT, and provides a safe and feasible surgical option for PTC patients.  相似文献   
95.
The purpose of this study was to investigate the efficacy of metformin as a radiosensitizer for use in combination therapy for human hepatocellular carcinoma (HCC). Three human HCC cell lines (Huh7, HepG2, Hep3B) and a normal human hepatocyte cell line were treated with metformin alone or with radiation followed by metformin. In vitro tests were evaluated by clonogenic survival assay, FACS analysis, western blotting, immunofluorescence and comet assay. Metformin significantly enhanced radiation efficacy under high and low Linear Energy Transfer (LET) radiation conditions in vitro. In combination with radiation, metformin abrogated G2/M arrest and increased the cell population in the sub-G1 phase and the ROS level, ultimately increasing HCC cellular apoptosis. Metformin inhibits the repair of DNA damage caused by radiation. The radiosensitizing effects of metformin are much higher in neutron (high LET)-irradiated cell lines than in γ (low LET)-irradiated cell lines. Metformin only had a moderate effect in normal hepatocytes. Metformin enhances the radiosensitivity of HCC, suggesting it may have clinical utility in combination cancer treatment with high-LET radiation.  相似文献   
96.
97.
98.
99.
100.
PurposePerioperative fluid management in kidney transplant recipients is crucial to supporting the fluid, acid-base, and electrolyte balance required for graft perfusion. However, the choice of intraoperative crystalloids in kidney transplantation remains controversial. We conducted a single-center retrospective cohort study to evaluate the impact of intraoperative fluids on acid-base and electrolyte balance and graft outcomes.Materials and MethodsWe included 282 living donor kidney transplant recipients from January 2010 to December 2017. Patients were classified into two groups based on the type of intraoperative crystalloids used (157 patients in the half saline group and 125 patients in the balanced crystalloid solutions group, Plasma-lyte).ResultsCompared with the half saline group, the Plasma-lyte group showed less metabolic acidosis and hyponatremia during surgery. Hyperkalemia incidence was not significantly different between the two groups. Changes in postoperative graft function assessed by blood urea nitrogen and creatinine were significantly different between the two groups. Patients in the Plasma-lyte group exhibited consistently higher glomerular filtration rates than those in the half saline group at 1 month and 1 year after transplantation after adjusting for demographic differences.ConclusionIntraoperative Plasma-lyte can lead to more favorable results in terms of acid-base balance during kidney transplantation. Patients who received Plasma-lyte showed superior postoperative graft function at 1 month and 1 year after transplantation. Further studies are needed to evaluate the superiority of intraoperative Plasma-lyte over other types of crystalloids in relation to graft outcomes.  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