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   1030篇
  免费   55篇
  国内免费   4篇
耳鼻咽喉   11篇
儿科学   18篇
妇产科学   15篇
基础医学   187篇
口腔科学   23篇
临床医学   117篇
内科学   192篇
皮肤病学   13篇
神经病学   97篇
特种医学   49篇
外国民族医学   1篇
外科学   159篇
综合类   15篇
预防医学   51篇
眼科学   28篇
药学   59篇
中国医学   11篇
肿瘤学   43篇
  2024年   3篇
  2023年   18篇
  2022年   44篇
  2021年   100篇
  2020年   50篇
  2019年   71篇
  2018年   54篇
  2017年   60篇
  2016年   42篇
  2015年   43篇
  2014年   67篇
  2013年   71篇
  2012年   102篇
  2011年   83篇
  2010年   35篇
  2009年   28篇
  2008年   44篇
  2007年   34篇
  2006年   34篇
  2005年   26篇
  2004年   16篇
  2003年   17篇
  2002年   13篇
  2001年   7篇
  2000年   4篇
  1999年   1篇
  1998年   1篇
  1996年   4篇
  1995年   1篇
  1994年   2篇
  1992年   3篇
  1991年   2篇
  1989年   1篇
  1987年   1篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1980年   1篇
  1978年   1篇
  1976年   1篇
  1974年   1篇
排序方式: 共有1089条查询结果,搜索用时 0 毫秒
991.
992.
993.

Objective

The purpose of this study is to investigate potential differences in the image quality of inpatient versus outpatient F-18-FDG PET/CT to provide evidence for appropriate policies and procedures to be promulgated on inpatient referrals.

Methods

100 consecutive inpatient and 100 outpatient F-18-FDG PET/CT scans were compared from the same time period and PET/CT scanner. Each study was evaluated for a subjective overall rating (optimal vs. suboptimal), and also by objective measurements (SUVmean) in four background structures (brain, blood pool, liver, and muscle).

Results

96 outpatient scans were rated optimal and 4 suboptimal whereas corresponding numbers for inpatient scans were 77 and 23 (p < 0.001). Of the objective indices, cerebellar SUV was significantly different in inpatient versus outpatient (5.3 vs. 6.9; p < 0.001) as well as suboptimal versus optimal rated groups (4.8 vs. 6.3; p < 0.001). While mean blood glucose was higher for inpatients (108.01 vs. 101.49 mg/dl; p = 0.017), it was not significantly different between optimal and suboptimal exams. Linear regression analysis between blood glucose levels and cerebellar uptake revealed an inverse relationship (R = ?0.38, p < 0.001).

Conclusions

There was a significantly higher number of inpatient PET/CT scans rated as suboptimal in comparison to outpatient scans. Decreased cerebellar uptake was present in suboptimal rated studies and in inpatient studies. Altered biodistribution is thus a potential etiology of reduced scan quality among inpatients. These findings, if duplicated among other readers and centers, may form the basis of quality control recommendations for inpatient PET/CT ordering patterns.  相似文献   
994.
Disease caused by Powassan virus (POWV), a tick-borne flavivirus, ranges from asymptomatic to severe neurologic compromise and death. Two cases of POWV meningoencephalitis in New York, USA, highlight diagnostic techniques, neurologic outcomes, and the effect of POWV on communities to which it is endemic.  相似文献   
995.
996.

Background

Human-infecting microsporidia are a group of spore-forming eukaryotic microorganisms that can infect both animals and humans. Recent evidences indicate waterborne transmission of microsporidia spores to human via either drinking water or irrigation of vegetable farms with contaminated water resources. The current study aimed to evaluate the presence of human-infecting microsporidia in treated wastewater (TW) and vegetable farms irrigated with treated wastewater during a year.

Methods

Totally, twelve samples of each treated wastewater and vegetables were collected. In order to recover microsporidia spores, filtration using cellulose nitrate membrane (pore size 0.4?μm) and sedimentation were employed. DNA extraction was performed for all samples and genus/species were characterized using specific primers. In order to characterize genotypes, ITS fragment of E. bieneusi was amplified, sequenced and compared in GenBank database. Phylogenetic tree was employed to analysis the probable correlation between obtained genotypes with those E. bieneusi genotypes, which were previously obtained from human and animals from same region.

Results

After nested PCR, expected fragments of E. bieneusi and Encephalitozoon spp were observed among 5/12 (41.7%) and 1/12 (8.33%) of vegetable samples, respectively. From total of 12 TW samples, expected fragments of E. bieneusi and Encephalitozoon spp were amplified among 7/12 (53.8%) and 1/12 (8.33%) of TW samples, respectively. Genotypes D and E were characterized from both TW and vegetables samples. Phylogenetic analysis showed close-relationship between E. bieneusi from TW and vegetable samples with E. bieneusi from animals and humans obtained from the same region.

Conclusion

Our findings suggested the key role of animals in epidemiology of zoonotic transmission of E. bieneusi. Moreover, our findings revealed the occurrence of human-infecting microsporidia in treated wastewater because of either insufficiency of treatment process or distribution of microsporidia spores in wastewater treatment plant via animals.  相似文献   
997.
Considering the application of human genome variation databases in precision medicine, population‐specific genome projects are continuously being developed. However, the Middle Eastern population is underrepresented in current databases. Accordingly, we established Iranome database ( www.iranome.com ) by performing whole exome sequencing on 800 individuals from eight major Iranian ethnic groups representing the second largest population of Middle East. We identified 1,575,702 variants of which 308,311 were novel (19.6%). Also, by presenting higher frequency for 37,384 novel or known rare variants, Iranome database can improve the power of molecular diagnosis. Moreover, attainable clinical information makes this database a good resource for classifying pathogenicity of rare variants. Principal components analysis indicated that, apart from Iranian‐Baluchs, Iranian‐Turkmen, and Iranian‐Persian Gulf Islanders, who form their own clusters, rest of the population were genetically linked, forming a super‐population. Furthermore, only 0.6% of novel variants showed counterparts in “Greater Middle East Variome Project”, emphasizing the value of Iranome at national level by releasing a comprehensive catalog of Iranian genomic variations and also filling another gap in the catalog of human genome variations at international level. We introduce Iranome as a resource which may also be applicable in other countries located in neighboring regions historically called Greater Iran (Persia).  相似文献   
998.
Parasitology Research - The study of pathogenesis mechanisms of larval stages in the Taeniidae has recently focused on host genetic factors, particularly toll-like receptor (TLR) variations....  相似文献   
999.
1000.
The paper used longitudinal Canadian data from the National Population Health Survey to estimate the impact of macroeconomic conditions measured by provincial unemployment rate on individual obesity and BMI. To control for individual‐specific unobserved heterogeneity, the study utilized the conditional fixed effect logit and fixed effects models. The study found that unemployment rate had a significant positive impact on the probability of being severely obese. The study also found that unemployment rate significantly increased BMI. However, the study did not find any significant impact of unemployment rate on the probability of being overweight or obese. Copyright © 2013 John Wiley & Sons, Ltd.  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