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   2940篇
  免费   202篇
  国内免费   23篇
耳鼻咽喉   42篇
儿科学   75篇
妇产科学   41篇
基础医学   442篇
口腔科学   241篇
临床医学   262篇
内科学   590篇
皮肤病学   73篇
神经病学   299篇
特种医学   47篇
外科学   271篇
综合类   11篇
预防医学   343篇
眼科学   46篇
药学   213篇
中国医学   25篇
肿瘤学   144篇
  2024年   4篇
  2023年   55篇
  2022年   97篇
  2021年   129篇
  2020年   95篇
  2019年   135篇
  2018年   152篇
  2017年   102篇
  2016年   113篇
  2015年   159篇
  2014年   186篇
  2013年   203篇
  2012年   286篇
  2011年   311篇
  2010年   163篇
  2009年   123篇
  2008年   161篇
  2007年   155篇
  2006年   135篇
  2005年   96篇
  2004年   79篇
  2003年   78篇
  2002年   70篇
  2001年   4篇
  1999年   6篇
  1998年   6篇
  1997年   7篇
  1996年   7篇
  1995年   4篇
  1994年   5篇
  1993年   5篇
  1991年   1篇
  1990年   2篇
  1989年   3篇
  1988年   5篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1983年   2篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
  1975年   1篇
  1973年   2篇
  1971年   1篇
  1968年   1篇
  1964年   1篇
  1957年   1篇
  1955年   1篇
  1924年   1篇
排序方式: 共有3165条查询结果,搜索用时 0 毫秒
81.

Purpose

Malnutrition is a strong predictor of mortality in hemodialysis patients. Several scoring systems for evaluating nutritional status have been proposed. However, they rely on different sets of anthropometric and laboratory markers to make a diagnosis of malnutrition and assess its impact on prognosis. To validate them, nutritional scores should be compared with clinical outcomes. Thus, the purpose of this study was to assess malnutrition by three different nutrition scoring systems and determine which best predicts mortality in hemodialysis patients.

Methods

This prospective study included 106 adult chronic hemodialysis patients. Their mean age was 56.3 ± 14.9 years and mean body mass index 24.8 (21.8–28.9); 52 % were men and they had been on dialysis for 24 (5–55) months. Nutritional status was classified according to the diagnostic systems proposed by Wolfson et al. (Am J Clin Nutr 39(4):547–555, 1984), International Society of Renal Nutrition and Metabolism (ISRNM) (Fouque et al. in Kidney Int 73(4):391–398, 2008), and Beberashvili et al. (Nephrol Dial Transplant 25(8):2662–2671, 2010). During about 2 years of follow-up, mortality was assessed by Kaplan–Meier curves, log-rank, and Cox’s models adjusted for diabetes, sex, C-reactive protein, time on dialysis, age, and fractional urea clearance.

Results

Twenty-three deaths (21.5 %) occurred during the study period. According to the systems of Wolfson, Beberashvili, and the ISRNM, 54, 32, and 20 % of patients, respectively, had malnutrition. Both univariate and multivariate analyses showed that the ISRNM system was the only one that predicted poorer survival (fourfold higher death risk) in malnourished patients.

Conclusions

The scoring system proposed by the ISRNM most accurately identifies patients at higher risk of death.  相似文献   
82.
ObjectiveTo assess the association of the polymorphisms of the interleukin-18 (IL-18) gene with rheumatoid arthritis (RA) and with risk factors for cardiovascular diseases (CVD).MethodsThis sample comprised 97 patients with RA and 151 healthy controls. In the patients, risk factors for CVD were analyzed, such as cholesterol levels, arterial hypertension, smoking habit, C-reactive protein (CRP) level, and rheumatoid factor. DNA was extracted and the single nucleotide polymorphisms (SNP) at the ?607C/A and ?137G/C positions of the IL-18 gene were assessed in both groups. The Hardy-Weinberg equilibrium (HWE) was calculated and the odds ratio (OR) test performed, considering a 95% CI and P < 0.05.ResultsThe frequencies of the ?607A allele in patients with RA and in controls were 0,443 and 0.424, respectively, and of the ?137C allele, 0.304 and 0.291, respectively. The genotype frequencies were in HWE, except for controls in the ?137 locus (P = 0.006). Association of the polymorphisms of the IL-18 gene was found with neither RA nor risk factors for CVD, including cholesterol level and CRP (P > 0.05). In addition, more smokers were found among patients with RA as compared with controls (OR = 1.691; P = 0.088), and the CRP levels were slightly higher in patients who smoked than in patients who did not (OR = 2.673; P = 0.061).ConclusionsIn this sample of patients with RA in the South of Brazil, association of the polymorphisms of the IL-18 gene was observed with neither RA nor risk factors for CVD.  相似文献   
83.
GABAergic transmission is essential to brain function, and a large repertoire of GABA type A receptor (GABAAR) subunits is at a neuron's disposition to serve this function. The glycine receptor (GlyR)‐associated protein gephyrin has been shown to be essential for the clustering of a subset of GABAAR. Despite recent progress in the field of gephyrin‐dependent mechanisms of postsynaptic GABAAR stabilisation, the role of gephyrin in synaptic GABAAR localisation has remained a complex matter with many open questions. Here, we analysed comparatively the interaction of purified rat gephyrin and mouse brain gephyrin with the large cytoplasmic loops of GABAAR α1, α2, β2 and β3 subunits. Binding affinities were determined using surface plasmon resonance spectroscopy, and showed an ~ 20‐fold lower affinity of the β2 loop to gephyrin as compared to the GlyR β loop–gephyrin interaction. We also probed in vivo binding in primary cortical neurons by the well‐established use of chimaeras of GlyR α1 that harbour respective gephyrin‐binding motifs derived from the different GABAAR subunits. These studies identify a novel gephyrin‐binding motif in GABAAR β2 and β3 large cytoplasmic loops.  相似文献   
84.
Prostate cancer is a key health concern for men with its etiology still under investigation. Recently, the role of dietary supplements has been noted to have a major inhibitory effect on prostate cancer and numerous studies have been conducted in this regard. This review provides a summary on numerous recent studies conducted in this field. Some of the studies reviewed revealed a protective role for supplements, and others showed no correlation while some even had an adverse effect. The mechanism of how these supplements act on the prostate is still not clear. Further studies are warranted especially for supplements that have been shown to have a potential inhibitory role in prostate cancer.  相似文献   
85.
The aim of this study was to evaluate the effect of a mixture of vitamins and minerals on oxidative DNA damage and the resistance of DNA to H(2)O(2)-induced DNA strand breaks in lymphocytes from 80 elderly volunteers ex vivo by means of Comet assay. The intervention with vitamin complex decreased significantly the levels of DNA damage. Our results demonstrate that the vitamin complex was able to decrease H(2)O(2)-induced DNA breakage. Our data suggest that the consumption of some vitamins may reduce the effects of oxidative DNA damage and may be useful for attaining healthy aging.  相似文献   
86.

Background

It is a challenge in low-resource settings to ensure the availability of complete, timely disease surveillance information. Smartphone applications (apps) have the potential to enhance surveillance data transmission.

Methods

The Central African Republic (CAR) Ministry of Health and Médecins Sans Frontières (MSF) conducted a 15-week pilot project to test a disease surveillance app, Argus, for 20 conditions in 21 health centers in Mambéré Kadéi district (MK 2016). Results were compared to the usual paper-based surveillance in MK the year prior (MK 2015) and simultaneously in an adjacent health district, Nana-Mambére (NM 2016). Wilcoxon rank sum and Kaplan-Meier analyses compared report completeness and timeliness; the cost of the app, and users’ perceptions of its usability were assessed.

Results

Two hundred seventy-one weekly reports sent by app identified 3403 cases and 63 deaths; 15 alerts identified 28 cases and 4 deaths. Median completeness (IQR) for MK 2016, 81% (81–86%), was significantly higher than in MK 2015 (31% (24–36%)), and NM 2016 (52% (48–57)) (p?<?0.01). Median timeliness (IQR) for MK 2016, 50% (39–57%) was also higher than in MK 2015, 19% (19–24%), and NM 2016 29% (24–36%) (p?<?0.01). Kaplan-Meier Survival Analysis showed a significant progressive reduction in the time taken to transmit reports over the 15-week period (p?<?0.01). Users ranked the app’s usability as greater than 4/5 on all dimensions. The total cost of the 15-week pilot project was US$40,575. It is estimated that to maintain the app in the 21 health facilities of MK will cost approximately US$18,800 in communication fees per year.

Conclusions

The app-based data transmission system more than doubled the completeness and timeliness of disease surveillance reports. This simple, low-cost intervention may permit the early detection of disease outbreaks in similar low-resource settings elsewhere.
  相似文献   
87.
88.
Background

Evidence-based policy measures need non-interest-guided information about the health status of a population and the diseases that affect the population the most. In such cases, a national burden of disease study can provide reliable insights at the regional level.

Aim

This article presents the potential of the BURDEN 2020 project and its expected outcome for Germany at the national and regional level.

Methods

The BURDEN 2020 project uses several indicators including years of life lost (YLL) to cover the impact of mortality and years lived with disability (YLD) to cover morbidity. The sum of both is the measure of population health called disability adjusted life years (DALY).

Results

The study ranks individual diseases and risk factors based on their impact on population health. The burden of disease approach is assumed to be sensitive to subnational differences and may generate immediate benefits for regional planning. The BURDEN 2020 study will pilot a national burden of disease study for Germany that will later be transformed into a continuous data processing and visualization tool. This is done by using, modifying and supplementing the methodology employed by the Global Burden of Disease (GBD) study to better fit the needs of health policy in Germany. This study is aimed at calculating the disease burden for up to 17 preselected diseases. Furthermore, the estimates of burden of disease are attributed to a selected set of risk factors.

Conclusion

The Burden 2020 study will provide the results of a new, health-related data processing system to the public. This includes a noninterest-guided presentation of the burden of disease (DALY) in Germany at the national and regional level.

  相似文献   
89.
90.
Neurosurgical Review - Traumatic brain injury (TBI) is the main cause of pediatric trauma death and disability worldwide. Recent studies have sought to identify biomarkers of TBI for the purpose of...  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