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   3507篇
  免费   233篇
  国内免费   14篇
耳鼻咽喉   45篇
儿科学   87篇
妇产科学   89篇
基础医学   573篇
口腔科学   267篇
临床医学   383篇
内科学   716篇
皮肤病学   52篇
神经病学   336篇
特种医学   37篇
外科学   264篇
综合类   51篇
一般理论   2篇
预防医学   353篇
眼科学   52篇
药学   236篇
中国医学   14篇
肿瘤学   197篇
  2024年   8篇
  2023年   54篇
  2022年   97篇
  2021年   170篇
  2020年   112篇
  2019年   122篇
  2018年   123篇
  2017年   94篇
  2016年   117篇
  2015年   109篇
  2014年   136篇
  2013年   167篇
  2012年   273篇
  2011年   308篇
  2010年   174篇
  2009年   134篇
  2008年   223篇
  2007年   182篇
  2006年   185篇
  2005年   162篇
  2004年   109篇
  2003年   94篇
  2002年   76篇
  2001年   18篇
  2000年   8篇
  1999年   16篇
  1998年   11篇
  1997年   18篇
  1996年   23篇
  1995年   11篇
  1994年   11篇
  1993年   8篇
  1992年   9篇
  1991年   9篇
  1990年   10篇
  1989年   7篇
  1987年   10篇
  1986年   6篇
  1985年   6篇
  1982年   7篇
  1980年   6篇
  1959年   29篇
  1958年   40篇
  1957年   31篇
  1956年   32篇
  1955年   28篇
  1954年   44篇
  1949年   18篇
  1948年   34篇
  1946年   7篇
排序方式: 共有3754条查询结果,搜索用时 15 毫秒
61.
This study was designed to describe the epidemiology and risk factors for nosocomial infection (NI) in a Brazilian neonatal intensive care unit (NICU). This study was a retrospective cohort from January to December, 2003. All neonates admitted to the NICU. Infection surveillance was conducted according to the NNIS, CDC. Chi-square test and logistic regression model were performed for statistical analyses. The study was conducted at a public, tertiary referral NICU of a teaching hospital in the Northeast of Brazil. A total of 948 medical records were reviewed. Overall NI incidence rate was 34%. The main neonatal NI was bloodstream infection (68.1%), with clinical sepsis accounting for 47.2%, and pneumonia was the second most common NI (8.6%). Multivariate analysis identified seven independent risk factors for NIs: birth weight, exposure to parenteral nutrition, percutaneous catheter, central venous catheter or mechanical ventilation, abruptio placentae and mother's sexually transmitted disease (STD). Neonates from mothers with STD or abruptio placentae, those weighing less than 1,500 g at birth or those who used invasive devices were at increased risk for acquiring NI.  相似文献   
62.
Metabolic Brain Disease - Acetylcholine is an excitatory neurotransmitter that modulates synaptic plasticity and communication, and it is essential for learning and memory processes. This...  相似文献   
63.

OBJECTIVE:

to assess patient knowledge of heart failure by home-based measurement of two NOC Nursing Outcomes over a six-month period and correlate mean outcome indicator scores with mean scores of a heart failure Knowledge Questionnaire.

METHODS:

in this before-and-after study, patients with heart failure received four home visits over a six-month period after hospital discharge. At each home visit, nursing interventions were implemented, NOC outcomes were assessed, and the Knowledge Questionnaire was administered.

RESULTS:

overall, 23 patients received home visits. Mean indicator scores for the outcome Knowledge: Medication were 2.27±0.14 at home visit 1 and 3.55±0.16 at home visit 4 (P<0.001); and, for the outcome Knowledge: Treatment Regimen, 2.33±0.13 at home visit 1 and 3.59±0.14 at home visit 4 (P<0.001). The correlation between the Knowledge Questionnaire and the Nursing Outcomes Classification scores was strong at home visit 1 (r=0.7, P<0.01), but weak and non significant at visit 4.

CONCLUSION:

the results show improved patient knowledge of heart failure and a strong correlation between Nursing Outcomes Classification indicator scores and Knowledge Questionnaire scores. The NOC Nursing Outcomes proved effective as knowledge assessment measures when compared with the validated instrument.  相似文献   
64.

Objective

To investigate the relationship of carotid artery intima-media thickness (IMT) and cardiac structure and function with adipocytokines in sedentary (S-SCI) and physically active (PA-SCI) subjects with spinal cord injury (SCI).

Design

Cross-sectional observational study.

Setting

Academic medical center.

Participants

Men with chronic (>1y) SCI (N=41; 16 S-SCI, 25 PA-SCI) were evaluated. S-SCI subjects did not perform labor that required physical effort, recreational physical activity, or sports, while PA-SCI subjects included competing athletes who were regularly performing adapted sports.

Interventions

Not applicable.

Main Outcome Measures

Clinical, laboratory, carotid ultrasonography, and echocardiography analysis. Plasma leptin, adiponectin, and plasminogen activating inhibitor-1 (PAI-1) levels were determined.

Results

PA-SCI subjects had similar levels of adipocytokines, but lower carotid IMT and carotid IMT/diameter, and better left ventricular diastolic function than S-SCI participants. Bivariate analysis showed that adiponectin was inversely correlated with triglycerides (r=–.85, P<.001), low-density lipoprotein cholesterol (r=–.57, P<.05), and carotid IMT/diameter (r=–.56, P<.05) in S-SCI but not in PA-SCI participants. Additionally, the leptin-adiponectin ratio showed a direct correlation with triglycerides (r=.84, P<.001) and low-density lipoprotein cholesterol (r=.53, P<.05) in S-SCI but not in PA-SCI individuals. By contrast, the studied adipocytokines did not correlate with cardiac structure and function in PA-SCI and S-SCI participants.

Conclusions

Lower adiponectin levels and higher leptin-adiponectin ratio are related to adverse vascular and/or metabolic characteristics in individuals with SCI. This relationship, however, appears to be mitigated by regular physical activity.  相似文献   
65.
66.
Since 1972, the World Health Organization (WHO) has declared noise as a pollutant. Over the last decades, the quality of the urban environment has attracted the interest of researchers due to the growing urban sprawl, especially in developing countries. The objective of this study was to evaluate the effects of noise exposure in six urban soundscapes: Areas with high and low levels of noise in scenarios of leisure, work, and home. Cross-sectional study. The study was conducted in two steps: Evaluation of noise levels, with the development of noise maps, and health related inquiries. 180 individuals were interviewed, being 60 in each scenario, divided into 30 exposed to high level of noise and 30 to low level. Chi-Square test and Ordered Logistic Regression Model (P < 0,005). 70% of the interviewees reported noticing some source of noise in the selected scenarios and it was observed an association between exposure and perception of some source of noise (P < 0.001). 41.7% of the interviewees reported some degree of annoyance, being that this was associated with exposure (P < 0.001). There was also an association between exposure in different scenarios and reports of poor quality of sleep (P < 0.001). In the scenarios of work and home, the chance of reporting annoyance increased when compared with the scenario of leisure. We conclude that the use of this sort of assessment may clarify the relationship between urban noise exposure and health.  相似文献   
67.
Clinical Rheumatology - Articular cartilage and periarticular muscle tissues are strongly affected during knee osteoarthritis (OA). Creatine kinase (CK) is an enzyme expressed in several tissues,...  相似文献   
68.
Clinical Rheumatology - FM is a chronic musculoskeletal disorder characterized by the presence of generalized pain. There are contradictory results regarding the prevalence and supplementation...  相似文献   
69.
Forensic Toxicology - We have developed and validated a high-sensitivity method to quantify lysergic acid diethylamide (LSD) and 2-oxo-3-hydroxy-LSD (OH-LSD) in oral fluid samples using...  相似文献   
70.
Interactions between killer immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) class I ligands influence development of natural killer (NK) cell repertoire and response to infection, cancer, and allogeneic tissue. As KIRs and HLA class I molecules are highly polymorphic, clinical allogeneic hematopoietic cell transplantation is predicted to frequently involve KIR mismatch, and thus to provide a unique system for study of human NK cell receptor repertoire development. Eighteen leukemia patients undergoing HLA-matched transplantation and their donors were analyzed for KIR genotype. Ten of 13 HLA-identical donor-patient pairs were KIR mismatched and 3 were matched; all HLA-matched unrelated pairs were KIR mismatched. Reconstitution of recipient NK cell repertoire following transplantation was examined using flow cytometry and monoclonal antibodies specific for KIR and CD94:NKG2A. These data form 3 groups. Six to 9 months after transplantation, 8 patients (group 1) reconstituted an NK cell repertoire resembling that of their donor, and for KIR-mismatched transplants, distinct from the recipient before transplantation. In the first year after transplantation, 5 patients (group 2) exhibited a generally depressed frequency of KIR-expressing NK cells and concomitant high frequency of CD94:NKG2A expression. By 3 years after transplantation, the frequency of KIR-expressing NK cells had increased to donor values, in the 3 patients from group 2 analyzed for this period. The remaining 5 patients experienced severe clinical complications following transplantation and displayed unique features in their NK cell receptor reconstitution. These results demonstrate that a majority of HLA-matched hematopoietic cell transplantations involve KIR mismatch and reveal differences in NK cell repertoire having potential impact for immune responsiveness and transplantation outcome.  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