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   4994篇
  免费   212篇
  国内免费   12篇
耳鼻咽喉   47篇
儿科学   138篇
妇产科学   247篇
基础医学   714篇
口腔科学   109篇
临床医学   360篇
内科学   990篇
皮肤病学   71篇
神经病学   429篇
特种医学   135篇
外科学   686篇
综合类   83篇
一般理论   4篇
预防医学   431篇
眼科学   123篇
药学   299篇
中国医学   16篇
肿瘤学   336篇
  2024年   26篇
  2023年   52篇
  2022年   95篇
  2021年   206篇
  2020年   100篇
  2019年   138篇
  2018年   158篇
  2017年   103篇
  2016年   118篇
  2015年   139篇
  2014年   176篇
  2013年   235篇
  2012年   366篇
  2011年   353篇
  2010年   184篇
  2009年   146篇
  2008年   285篇
  2007年   275篇
  2006年   264篇
  2005年   255篇
  2004年   236篇
  2003年   200篇
  2002年   203篇
  2001年   41篇
  2000年   43篇
  1999年   33篇
  1998年   44篇
  1997年   45篇
  1996年   25篇
  1995年   28篇
  1994年   41篇
  1993年   31篇
  1992年   32篇
  1991年   28篇
  1990年   32篇
  1989年   23篇
  1988年   31篇
  1987年   22篇
  1986年   25篇
  1985年   17篇
  1984年   20篇
  1983年   17篇
  1982年   24篇
  1981年   20篇
  1980年   21篇
  1979年   24篇
  1978年   17篇
  1976年   14篇
  1975年   14篇
  1969年   10篇
排序方式: 共有5218条查询结果,搜索用时 15 毫秒
81.
Introduction and objectivesCOVID-19 is currently causing high mortality and morbidity worldwide. Information on cardiac injury is scarce. We aimed to evaluate cardiovascular damage in patients with COVID-19 and determine the correlation of high-sensitivity cardiac-specific troponin T (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) with the severity of COVID-19.MethodsWe included 872 consecutive patients with confirmed COVID-19 from February to April 2020. We tested 651 patients for high-sensitivity troponin T (hs-TnT) and 506 for NT-proBNP on admission. Cardiac injury was defined as hs-TnT > 14 ng/L, the upper 99th percentile. Levels of NT-proBNP > 300 pg/mL were considered related to some extent of cardiac injury. The primary composite endpoint was 30-day mortality or mechanical ventilation (MV).ResultsCardiac injury by hs-TnT was observed in 34.6% of our COVID-19 patients. Mortality or MV were higher in cardiac injury than noncardiac injury patients (39.1% vs 9.1%). Hs-TnT and NT-proBNP levels were independent predictors of death or MV (HR, 2.18; 95%CI, 1.23-3.83 and 1.87 (95%CI, 1.05-3.36), respectively) and of mortality alone (HR, 2.91; 95%CI, 1.211-7.04 and 5.47; 95%CI, 2.10-14.26, respectively). NT-ProBNP significantly improved the troponin model discrimination of mortality or MV (C-index 0.83 to 0.84), and of mortality alone (C-index 0.85 to 0.87).ConclusionsMyocardial injury measured at admission was a common finding in patients with COVID-19. It reliably predicted the occurrence of mortality and need of MV, the most severe complications of the disease. NT-proBNP improved the prognostic accuracy of hs-TnT.  相似文献   
82.

Introduction and objectives

To assess the validity of the original low-risk SCORE function without and with high-density lipoprotein cholesterol and SCORE calibrated to the Spanish population.

Methods

Pooled analysis with individual data from 12 Spanish population-based cohort studies. We included 30 919 individuals aged 40 to 64 years with no history of cardiovascular disease at baseline, who were followed up for 10 years for the causes of death included in the SCORE project. The validity of the risk functions was analyzed with the area under the ROC curve (discrimination) and the Hosmer-Lemeshow test (calibration), respectively.

Results

Follow-up comprised 286 105 persons/y. Ten-year cardiovascular mortality was 0.6%. The ratio between estimated/observed cases ranged from 9.1, 6.5, and 9.1 in men and 3.3, 1.3, and 1.9 in women with original low-risk SCORE risk function without and with high-density lipoprotein cholesterol and calibrated SCORE, respectively; differences were statistically significant with the Hosmer-Lemeshow test between predicted and observed mortality with SCORE (P < .001 in both sexes and with all functions). The area under the ROC curve with the original SCORE was 0.68 in men and 0.69 in women.

Conclusions

All versions of the SCORE functions available in Spain significantly overestimate the cardiovascular mortality observed in the Spanish population. Despite the acceptable discrimination capacity, prediction of the number of fatal cardiovascular events (calibration) was significantly inaccurate.Full English text available from:www.revespcardiol.org/en  相似文献   
83.

Objective:

This study is to determine the pattern of overweight and obesity and its relationship with childhood anthropometric status in Nigeria.

Materials and Methods:

This cross-sectional study was conducted in Jos, Nigeria. Interviewer administered questionnaire was used in data collection. Maternal and child anthropometric measurements were obtained using standard WHO methods. Child anthropometric Z scores were obtained from WHO Anthroplus while BMI of mothers were also determined. Totally, 262 mother-child pairs were recruited.

Results:

Mean maternal age and mean child age were 30.8 ± 6.3 yrs (15-47 yrs) and 22.3 ± 18.7 months (3-72 months). Prevalence of maternal underweight, overweight and obesity was 4.2% (11/262), 29.4% (77/262) and 25.9% (68/262), respectively. Child overweight/obesity was 5.4% (14/262), severe under-nutrition 5.7% (15/262). Mean maternal BMI was higher in the older, more educated and higher socioeconomic status (SES). Child mean birth-weight, weight-for-age Z-score and BMI-for-age Z-score (BAZ) were higher among mothers with BMI ≥ 25 kg/m2. All large-for-age babies were in mothers with maternal BMI ≥ 25 kg/m2. Childhood over-nutrition was more common in maternal BMI of ≥25 kg/m2. Overall, BAZ was directly related with maternal BMI, maternal age and birth-weight, although it was inversely related with maternal BM I ≥ 25 kg/m2.

Conclusion:

Higher BMI is seen in educated and higher SES mothers and this impact on childhood anthropometry.  相似文献   
84.
85.
The current study used event-related potentials to examine a candidate process through which sleep difficulties affect attentional processing in toddlers. Fifteen toddlers participated in an auditory Oddball task while neurophysiological data were collected. Sleep deficits were assessed using actigraphs, and attention was examined with a sustained attention task. A P3-like component was elicited from the toddlers, and longer target P3 latencies were associated with poorer sustained attention and irregular sleep. Findings suggest that irregular sleep is associated with less efficient attentional processing as reflected by the P3 component, and that longer target P3 latencies are associated with poorer sustained attention.  相似文献   
86.
87.
88.
89.
Background: Alcohol is heavily consumed in sub‐Saharan Africa and affects HIV transmission and treatment and is difficult to measure. Our goal was to examine the test characteristics of a direct metabolite of alcohol consumption, phosphatidylethanol (PEth). Methods: Persons infected with HIV were recruited from a large HIV clinic in southwestern Uganda. We conducted surveys and breath alcohol concentration (BRAC) testing at 21 daily home or drinking establishment visits, and blood was collected on day 21 (n = 77). PEth in whole blood was compared with prior 7‐, 14‐, and 21‐day alcohol consumption. Results: (i) The receiver operator characteristic area under the curve (ROC‐AUC) was highest for PEth versus any consumption over the prior 21 days (0.92; 95% confidence interval [CI]: 0.86 to 0.97). The sensitivity for any detectable PEth was 88.0% (95% CI: 76.0 to 95.6) and the specificity was 88.5% (95% CI: 69.8 to 97.6). (ii) The ROC‐AUC of PEth versus any 21‐day alcohol consumption did not vary with age, body mass index, CD4 cell count, hepatitis B virus infection, and antiretroviral therapy status, but was higher for men compared with women (p = 0.03). (iii) PEth measurements were correlated with several measures of alcohol consumption, including number of drinking days in the prior 21 days (Spearman r = 0.74, p < 0.001) and BRAC (r = 0.75, p < 0.001). Conclusions: The data add support to the body of evidence for PEth as a useful marker of alcohol consumption with high ROC‐AUC, sensitivity, and specificity. Future studies should further address the period and level of alcohol consumption for which PEth is detectable.  相似文献   
90.
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