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   40860篇
  免费   3354篇
  国内免费   126篇
耳鼻咽喉   360篇
儿科学   1073篇
妇产科学   795篇
基础医学   5506篇
口腔科学   701篇
临床医学   4427篇
内科学   8558篇
皮肤病学   585篇
神经病学   3607篇
特种医学   1365篇
外科学   6782篇
综合类   567篇
现状与发展   1篇
一般理论   43篇
预防医学   3246篇
眼科学   788篇
药学   3000篇
  3篇
中国医学   52篇
肿瘤学   2881篇
  2023年   304篇
  2022年   537篇
  2021年   1203篇
  2020年   641篇
  2019年   1032篇
  2018年   1173篇
  2017年   827篇
  2016年   878篇
  2015年   1013篇
  2014年   1390篇
  2013年   1811篇
  2012年   2787篇
  2011年   2892篇
  2010年   1511篇
  2009年   1343篇
  2008年   2240篇
  2007年   2257篇
  2006年   2125篇
  2005年   1987篇
  2004年   1902篇
  2003年   1819篇
  2002年   1687篇
  2001年   637篇
  2000年   637篇
  1999年   621篇
  1998年   431篇
  1997年   322篇
  1996年   309篇
  1995年   299篇
  1994年   274篇
  1993年   259篇
  1992年   502篇
  1991年   423篇
  1990年   459篇
  1989年   408篇
  1988年   407篇
  1987年   402篇
  1986年   372篇
  1985年   392篇
  1984年   348篇
  1983年   289篇
  1982年   232篇
  1981年   201篇
  1980年   201篇
  1979年   284篇
  1978年   227篇
  1977年   166篇
  1976年   149篇
  1974年   153篇
  1973年   162篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
ContextA single clinical assessment device that can be used to objectively measure scapular motion in each anatomical plane is not currently available. The development of a novel electric goniometer would allow scapular motion in all 3 anatomical planes to be quantified.ObjectiveTo investigate the reliability and validity of an electric goniometer for measuring scapular motion in each anatomical plane during upper extremity elevation.DesignCross-sectional study.SettingLaboratory.Patients or Other ParticipantsSixty participants (29 women, 31 men; age = 30 ± 14 years, height = 1.73 ± 0.10 m, mass = 75.32 ± 16.90 kg) recruited from the general population.Intervention(s)An electric goniometer was used to record clinical measurements of scapular position at rest and total arc of motion (excursion) during active upper extremity elevation in 2 testing sessions separated by several days. Measurements were recorded independently by 2 examiners. In 1 session, scapular motion was recorded simultaneously using a 14-camera, 3-dimensional optical motion-capture system.Main Outcome Measure(s)Reliability analysis included examination of clinical measurements for scapular position at rest and excursion during each condition. Both the intrarater reliability between testing sessions and the interrater reliability recorded in the same session were assessed using intraclass correlation coefficients (ICCs [2,3]). The criterion validity was examined by comparing the mean excursion values of each condition recorded using the electric goniometer and the 3-dimensional optical motion-capture system. Validity was assessed by evaluating the average difference and root mean square error.ResultsThe between-sessions intrarater reliability was moderate to good (ICC [2,3] range = 0.628–0.874). The within-session interrater reliability was moderate to excellent (ICC [2,3] range = 0.545–0.912). The average difference between total excursion values recorded using the electric goniometer and the 3-dimensional optical motion-capture system ranged from −7° to 4°, and the root mean square error ranged from 7° to 10°.ConclusionsThe reliability of scapular measurements was best when a standard operating procedure was used. The electric goniometer provided an accurate measurement of scapular excursions in all 3 anatomical planes during upper extremity elevation.  相似文献   
992.
993.
ObjectiveTo quantify changes in segmented brain volumes over 12 months in children with mucopolysaccharidosis types IIIA and IIIB (MPS IIIA and IIIB).MethodsIn order to establish suitable outcome measures for clinical trials, twenty-five children greater than 2 years of age were enrolled in a prospective natural history study of MPS IIIA and IIIB at Nationwide Children's Hospital. Data from sedated non-contrast brain 3 T MRIs and neuropsychological measures were reviewed from the baseline visit and at 12-month follow-up. No intervention beyond standard clinical care was provided. Age- and sex-matched controls were gathered from the National Institute of Mental Health Data Archive. Automated brain volume segmentation with longitudinal processing was performed using FreeSurfer.ResultsOf the 25 subjects enrolled with MPS III, 17 children (4 females, 13 males) completed at least one MRI with interpretable volumetric data. The ages ranged from 2.8 to 13.7 years old (average 7.2 years old) at enrollment, including 8 with MPS IIIA and 9 with MPS IIIB. At baseline, individuals with MPS III demonstrated reduced cerebral white matter and corpus callosum volumes, but greater volumes of the lateral ventricles, cerebellar cortex, and cerebellar white matter compared to controls. Among the 13 individuals with MPS III with two interpretable MRIs, there were annualized losses or plateaus in supratentorial brain tissue volumes (cerebral cortex ?42.10 ± 18.52 cm3/year [mean ± SD], cerebral white matter ?4.37 ± 11.82 cm3/year, subcortical gray matter ?6.54 ± 3.63 cm3/year, corpus callosum ?0.18 ± 0.62 cm3/yr) and in cerebellar cortex (?0.49 ± 12.57 cm3/year), with a compensatory increase in lateral ventricular volume (7.17 ± 6.79 cm3/year). Reductions in the cerebral cortex and subcortical gray matter were more striking in individuals younger than 8 years of age. Greater cerebral cortex volume was associated with higher fine and gross motor functioning on the Mullen Scales of Early Learning, while greater subcortical gray matter volume was associated with higher nonverbal functioning on the Leiter International Performance Scale. Larger cerebellar cortex was associated with higher receptive language performance on the Mullen, but greater cerebellar white matter correlated with worse adaptive functioning on the Vineland Adaptive Behavioral Scales and visual problem-solving on the Mullen.ConclusionsLoss or plateauing of supratentorial brain tissue volumes may serve as longitudinal biomarkers of MPS III age-related disease progression compared to age-related growth in typically developing controls. Abnormally increased cerebellar white matter in MPS III, and its association with worse performance on neuropsychological measures, suggest the possibility of pathophysiological mechanisms distinct from neurodegeneration-associated atrophy that warrant further investigation.  相似文献   
994.
995.
International Journal of Legal Medicine - Between the ever-increasing availability of surveillance evidence and expert-based forensic facial comparison being considered admissible in court,...  相似文献   
996.
Telomere length (TL) has been associated with aging and mortality, but individual differences are also influenced by genetic factors, with previous studies reporting heritability estimates ranging from 34 to 82%. Here we investigate the heritability, mode of inheritance and the influence of parental age at birth on TL in six large, independent cohort studies with a total of 19 713 participants. The meta-analysis estimate of TL heritability was 0.70 (95% CI 0.64–0.76) and is based on a pattern of results that is highly similar for twins and other family members. We observed a stronger mother–offspring (r=0.42; P-value=3.60 × 10−61) than father–offspring correlation (r=0.33; P-value=7.01 × 10−5), and a significant positive association with paternal age at offspring birth (β=0.005; P-value=7.01 × 10−5). Interestingly, a significant and quite substantial correlation in TL between spouses (r=0.25; P-value=2.82 × 10−30) was seen, which appeared stronger in older spouse pairs (mean age ≥55 years; r=0.31; P-value=4.27 × 10−23) than in younger pairs (mean age<55 years; r=0.20; P-value=3.24 × 10−10). In summary, we find a high and very consistent heritability estimate for TL, evidence for a maternal inheritance component and a positive association with paternal age.  相似文献   
997.
Clinical Oral Investigations - To investigate the oral health status and treatment needs of children with fetal alcohol spectrum disorder (FASD). In this retrospective study, the records of...  相似文献   
998.
Highlights? Inducible loss of the Syk tyrosine kinase results in death of follicular B cells ? Syk transduces survival signals from BAFFR to the ERK and PI3 kinase-PDK1 pathways ? BAFFR signaling results in phosphorylation of Igα and Syk ? BAFFR transduces signals via the BCR to activation of Syk  相似文献   
999.
1000.
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