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   5180篇
  免费   325篇
  国内免费   26篇
耳鼻咽喉   101篇
儿科学   86篇
妇产科学   135篇
基础医学   802篇
口腔科学   691篇
临床医学   410篇
内科学   995篇
皮肤病学   171篇
神经病学   335篇
特种医学   74篇
外科学   434篇
综合类   15篇
一般理论   2篇
预防医学   566篇
眼科学   48篇
药学   435篇
中国医学   50篇
肿瘤学   181篇
  2024年   12篇
  2023年   92篇
  2022年   170篇
  2021年   261篇
  2020年   173篇
  2019年   237篇
  2018年   268篇
  2017年   192篇
  2016年   216篇
  2015年   241篇
  2014年   300篇
  2013年   350篇
  2012年   477篇
  2011年   562篇
  2010年   258篇
  2009年   197篇
  2008年   320篇
  2007年   294篇
  2006年   233篇
  2005年   216篇
  2004年   165篇
  2003年   112篇
  2002年   94篇
  2001年   10篇
  2000年   6篇
  1999年   7篇
  1998年   7篇
  1997年   13篇
  1996年   4篇
  1995年   13篇
  1994年   7篇
  1993年   4篇
  1992年   4篇
  1990年   2篇
  1985年   2篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   4篇
  1976年   1篇
  1964年   1篇
排序方式: 共有5531条查询结果,搜索用时 15 毫秒
991.
Cruzipain (Cz), a key Trypanosoma cruzi enzyme, is a main candidate antigen for vaccines against Chagas' disease. We evaluated a vaccination protocol based on intradermal priming with recombinant Cz and intranasal boosting with rCz co-administered with a derivative of the TLR2/6 agonist MALP-2. Vaccination triggered strong systemic and mucosal antibody responses, and a vigorous cell-mediated immunity characterized by lymphoproliferation, DTH reactivity and IFN-gamma production. The immune responses protected against a lethal trypomastigote challenge and, upon sub-lethal infection, immunized mice showed reduction of tissue damage and normal enzymatic markers of muscle injury. This prime-boost regimen appears promising for further development, since warranted survival, provided efficient control of parasite load and restricted inflammatory myopathy.  相似文献   
992.
993.
OBJECTIVE: This study aimed to assess the relative validity of a food frequency questionnaire (FFQ), previously validated to measure usual intakes in adults, for measuring dietary intakes in children 5 to 10 y of age. METHODS: Dietary intakes were measured using an FFQ and a 3-d dietary record. Healthy children, 5 to 10 y old (n = 151), were recruited from public schools and asked to answer the questions in the FFQ and to provide non-consecutive 3-d dietary records based on reported estimated portion sizes. Paired sample t tests and Pearson's correlation coefficients were conducted to determine whether the two instruments reported similar values for energy and nutrients. The agreement of quartile categorization between the two instruments was also examined. RESULTS: Estimated energy and nutrient intakes derived from the FFQ were significantly higher than those derived from 3-d dietary records. As expected, Pearson's correlations increased after adjusting for residual measurement error, presumably due to exclusion of the high within-person variability in intake of these nutrients. Moderate to high (r > 0.50) correlation coefficients were verified for some nutrients such as calcium, folate, vitamin B2, vitamin A, and vitamin C. CONCLUSION: This FFQ, originally developed for use in adults, appears to overestimate usual energy and nutrient intakes in children 5 to 10 y of age. Further work is necessary to conduct a calibration study to establish adequate portion sizes before instrument adoption in this population.  相似文献   
994.

Background

The adoption of prospectively ECG-triggered acquisition coronary computed tomography angiography (CTA) has resulted in the inability to measure left ventricle (LV) end-diastolic volume and LV ejection fraction. However other prognostic measures such as LV mass and LV mid-diastolic volume (LVMDV) can still be assessed. The objective of this study is to establish normal reference values for LVMDV and LV mass.

Methods

Left ventricular mid-diastolic volumes and LV mass were prospectively measured in 2647 consecutive ‘normal’ patients undergoing prospectively ECG-triggered coronary CTA. Patients with known coronary artery disease (prior myocardial infarction or prior revascularization), heart failure, congenital heart disease, heart transplant or prior cardiac surgery were excluded. Commercially available software was used to calculate the LVMDV and LV mass.

Results

Among the 2647 patient cohort (mean age = 58 years, 54% men), the mean LVMDV indexed for body surface area was 57.5 ± 15.3 mL/m2 and 64.5 ± 20.2 mL/m2 for women and men, respectively. The mean indexed LV mass was 52.2 ± 10.9 g/m2 for women and 63.6 ± 13.7 g/m2 for men. Indexed LVMDV decreased with increasing age. The presence of hypertension, diabetes and obstructive coronary artery disease did not have a clinically relevant impact on these values. Age and sex specific upper limits of normal were defined.

Conclusion

We establish normal reference ranges for LVMDV and LV mass using prospectively ECG-triggered coronary CTA. These benchmarks may identify patients at increased risk of adverse events, supporting the potential for clinical reporting of these metrics.  相似文献   
995.
The aim of this study was to compare the predictions of Framingham cardiovascular (CV) risk score (FRS) and the American College of Cardiology/American Heart Association (ACC/AHA) risk score in an HIV outpatient clinic in the city of Vitoria, Espirito Santo, Brazil. In a cross-sectional study 341 HIV infected patients over 40 years old consecutively recruited were interviewed. Cohen's kappa coefficient was used to assess agreement between the two algorithms. 61.3% were stratified as low risk by Framingham score, compared with 54% by ACC/AHA score (Spearman correlation 0.845; p < 0.000). Only 26.1% were classified as cardiovascular high risk by Framingham compared to 46% by ACC/AHA score (Kappa = 0.745; p < 0.039). Only one out of eight patients had cardiovascular high risk by Framingham at the time of a myocardial infarction event registered up to five years before the study period. Both cardiovascular risk scores but especially Framingham underestimated high-risk patients in this HIV-infected population.  相似文献   
996.
997.
998.
999.
Introduction: A balanced maternal diet is a determining factor in normal fetal development. The objective of this study was to evaluate the effects of maternal protein restriction during pregnancy and lactation on muscle fiber and neuromuscular junction (NMJ) morphology of rat offspring at 21 days of age. Methods: Wistar rats were divided into a control group (CG), offspring of mothers fed a normal protein diet (17%), and a restricted group (RG), offspring of mothers fed a low‐protein diet (6%). After a period of lactation, the animals were euthanized, and soleus muscles were obtained from pups for analysis. Results: The soleus muscles of the RG exhibited an increase of 133% in the number of fibers and of 79% in the amount of nuclei. Moreover, the number of NMJs was lower in the restricted group than in the CG. Conclusions: Maternal protein restriction alters the normal development of the neuromuscular system. Muscle Nerve 55 : 109–115, 2017  相似文献   
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