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   7415篇
  免费   133篇
  国内免费   56篇
耳鼻咽喉   90篇
儿科学   3篇
妇产科学   55篇
基础医学   2143篇
口腔科学   106篇
临床医学   407篇
内科学   1771篇
皮肤病学   38篇
神经病学   1125篇
特种医学   169篇
外科学   445篇
综合类   276篇
一般理论   2篇
预防医学   429篇
眼科学   91篇
药学   277篇
中国医学   118篇
肿瘤学   59篇
  2023年   71篇
  2022年   146篇
  2021年   224篇
  2020年   195篇
  2019年   219篇
  2018年   212篇
  2017年   225篇
  2016年   158篇
  2015年   194篇
  2014年   463篇
  2013年   557篇
  2012年   371篇
  2011年   450篇
  2010年   348篇
  2009年   365篇
  2008年   379篇
  2007年   318篇
  2006年   253篇
  2005年   212篇
  2004年   194篇
  2003年   184篇
  2002年   144篇
  2001年   102篇
  2000年   139篇
  1999年   88篇
  1998年   107篇
  1997年   117篇
  1996年   91篇
  1995年   87篇
  1994年   79篇
  1993年   88篇
  1992年   64篇
  1991年   68篇
  1990年   62篇
  1989年   63篇
  1988年   43篇
  1987年   45篇
  1986年   27篇
  1985年   96篇
  1984年   97篇
  1983年   70篇
  1982年   58篇
  1981年   50篇
  1980年   33篇
  1979年   8篇
  1978年   11篇
  1977年   6篇
  1975年   5篇
  1974年   4篇
  1971年   3篇
排序方式: 共有7604条查询结果,搜索用时 15 毫秒
1.
DNA损伤是衰老相关疾病领域的研究热点, 可引起细胞周期停滞、凋亡, 加快个体衰老速度、增加衰老相关疾病的患病风险。本文将从细胞衰老和个体衰老两个层面阐述其与衰老之间的研究进展, 并综述其与衰老常见相关疾病(肿瘤、心血管疾病、阿尔茨海默病)及早衰综合征的关系, 为抗衰老研究和临床干预衰老相关疾病提供理论依据。  相似文献   
2.
Age-related cognitive decline is the major cause of concern due to its 70% more incidence than dementia cases worldwide. Moreover, aging is also the major risk factor of Alzheimer's disease (AD), associated with progressive memory loss. Approx. 13 million people will have Alzheimer-related memory decline by 2050. Learning and memory is the fundamental process of brain functions. However, the mechanism for the same is still under investigation. Thus, it is critical to understand the process of memory consolidation in the brain and extrapolate its understanding to the memory decline mechanism. Research on learning and memory has identified several molecular signatures such as Protein kinase M zeta (PKMζ), Calcium/calmodulin-dependent protein kinase II (CaMKII), Brain-derived neurotrophic factor (BDNF), cAMP-response element binding protein (CREB) and Activity-regulated cytoskeleton-associated protein (Arc) crucial for the maintenance and stabilization of long-term memory in the brain. Interestingly, memory decline in AD has also been linked to the abnormality in expressing these memory-related molecular signatures. Hence, in the present consolidated review, we explored the role of these memory-related molecular signatures in long-term memory consolidation. Additionally, the effect of amyloid-beta toxicity on these molecular signatures is discussed in detail.  相似文献   
3.
Low- and middle-income countries (LMICs) bear the greatest burden of cardiovascular disease (CVD) worldwide. Emerging evidence, mostly from industrialized countries, suggest that neighborhood characteristics influence cardiovascular health. This study presents results from 27,797 participants living in six LMICs on the association of perceived neighborhood social cohesion, the degree of connectedness among neighbors, with 10-year risk of CVD. We observed that greater perceived neighborhood social cohesion was associated with lower odds of high (>20%) 10-year CVD risk (OR = 0.67, 95%CI: 0.53–0.86). These novel findings, suggest that interventions to enhance social cohesion may have beneficial effects on cardiovascular health in LMICs.  相似文献   
4.
IntroductionLong-term care hospitals (LTCHs) are at a high risk for the inflow and spread of antimicrobial resistance (AMR) pathogens. However, owing to limited laboratory resources, little is known about the extent to which AMR organisms are endemic.MethodsWe performed active surveillance for carbapenem-resistant Enterobacteriaceae (CRE) and extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) in newly admitted patients at Marugame Medical Center, a nearly 200-bedded LTCH located in Kagawa, Japan. From August to December 2021, we tested stool samples from patients wearing diapers and confirmed the genetic variants using specific PCR assays. We also collected clinical variables and compared them between AMR carriers and non-carriers.ResultsStool samples were collected from 75 patients, with a median age of 84 years. CRE strain was not detected, but 37 strains of ESBL-E were isolated from 32 patients (42.7%). During the study period, 4.9% of in-hospital patients (37 per 756 patients) were identified to be ESBL-E carriers in the routine microbiological processing, suggesting that active surveillance detected approximately 9-fold more ESBL-E carriers. The blaCTX-M-9 group was the most common (38.5%), followed by the blaTEM (26.9%). The clinical backgrounds of the ESBL-E non-carriers and carriers were not significantly different.ConclusionOur active screening demonstrated that nearly half of the patients hospitalized or transferred to a Japanese LTCH were colonized with ESBL-E. We highlight the enforcement of universal basic infection prevention techniques at LTCHs where patients carrying AMR pathogens gather.  相似文献   
5.

Objectives

We examined the association between three inflammatory markers (Interleukin (IL)-6, C-reactive protein (CRP), tumor necrosis factor (TNF)-α) and incident lung cancer using baseline, updated, and averaged inflammatory measures in older adults.

Methods

We fitted multivariable Cox models to assess whether circulating levels of inflammation markers were associated with incident lung cancers in the Health Aging, Body and Composition (HealthABC) prospective cohort of 3075 older adults aged 70–79?years at baseline. IL-6 and CRP were measured biennially, whereas TNF-α was measured at baseline.

Results

Baseline levels of IL-6 were significantly associated with incident lung cancer risk in a model that adjusted for age, gender, race, and site (Model 1) (Hazard RatioT3 vs. T1: 3.34, 95% Confidence Interval: 1.91, 5.85) and in a model adjusted for health factors linked to chronic inflammation (Model 2) (HR T3 vs. T1: 2.57, 95% CI: 1.41, 4.65). The associations observed in time-updated IL-6 (HR T3 vs. T1: 2.47, 95% CI: 1.43, 4.28), cumulatively averaged IL-6 (HR T3 vs. T1: 2.47, 95% CI: 1.43, 4.35), and baseline CRP levels (HR T3 vs. T1: 1.85, 95% CI: 1.11, 3.08) with incident lung cancer in Model 1 were not statistically significant in Model 2.

Conclusions

Baseline CRP and IL-6 levels were associated with increased risk of lung cancer in Model 1 and both models, respectively. Chronic IL-6 inflammation, as quantified by repeated measures was associated with incident lung cancer in Model 1, but not Model 2. Further research is needed to understand the role of CRP and IL-6 in lung carcinogenesis.  相似文献   
6.
IntroductionQuality of life is now part of the discussion, when considering spinal arthrodesis in children and teenagers with severe cerebral palsy and scoliosis. From the subjective point of view of close caregivers, quality of life is significantly improved two to five years after surgery. Nevertheless information relevant to the long-term evolution of those patients, most of them institutionalized, is lacking. In this study the quality of life of 45 adult cerebral palsy subjects with scoliosis (20 with arthrodesis and 25 without), classified IV or V on the Gross Motor Classification System and living in institutions was questioned.Material and methodFour items: daily care, pain/comfort, sitting position and communication, were proposed to evaluation by professional caregivers, blind to the final goal of the study and asked to answer along a Lickert scale (−2 to +2).ResultsResults show that professional caregivers dont make any difference between operated and non operated patients when considering easiness of daily care, pain/comfort of the resident or ability to communicate, but judge sitting position to be slightly better for those with spinal arthrodesis. Satisfaction with sitting posture depends for one part on the degree of scoliotic curve but other factors (hip and knee rigidity, quality of the sitting orthosis) also seem to be relevant.ConclusionSpinal arthrodesis is beneficial for sitting posture, even in aging subjects with severe cerebral palsy and scoliosis living in institutions. But the study also points to the numerous other health challenges which negatively affect the quality of life of such patients.  相似文献   
7.
BackgroundPrevious studies on the age-, climate, and skin care habit-related changes of biophysical parameters have mainly focused on Caucasians, and studies on Asians are in paucity.ObjectiveThis study was aimed to investigate the variations of cutaneous biophysical parameters in Chinese and Korean women (northeast Asians) and to assess the association between those parameters and age, climate, and cosmetic habits.MethodsA cross-sectional study included 361 healthy Chinese and Korean women between 18 and 49 years of age in 4 cities (Guangzhou, Nanjing, and Shijiazhuang in China, and Suwon in Korea). We measured skin surface temperature, hydration, transepidermal water loss (TEWL), sebum, elasticity, skin pore, wrinkle, and skin tone (brightness) using non-invasive instruments. Demographic profiles and cosmetic habits were assessed using a questionnaire.ResultsSkin elasticity and tone decreased, and pore size and wrinkle increased with age. Subjects in Suwon (Korean) showed higher hydration level, lower TEWL and lower sebum, less severe wrinkle and brighter skin than those in the 3 cities in China. After adjusting for age and region, using sunscreen everyday, wearing base makeup daily, and using moisturizers improved hydration, TEWL, and elasticity significantly.ConclusionWomen in Suwon (Korea) were found to have a better profile of biophysical parameters than women in the 3 Chinese cities, which might be attributed to cosmetic habits, besides age and climatic factors. The fact that appropriate cosmetic habits are associated with favorable skin biophysical parameters underscores the importance of daily skin care routine in preserving skin functions.  相似文献   
8.
9.

Background

Clear cell renal cell carcinoma (ccRCC) is known to occur across the adult lifetime traversing the spectrum of age-related organismal changes. Little is known as to how the aging process may affect the course of renal cell carcinoma (RCC) and the repertoire of genes involved.

Methods

Using The Cancer Genome Atlas (n?=?436) and Cancer Genomics of the Kidney (n?=?89) datasets, we applied regression analysis to examine associations between patient age and gene expression profiles in ccRCC tumors and normal kidney tissues. Pathway enrichment analysis was performed to identify cellular process that is affected by aging in ccRCC. Moreover, connectivity mapping analysis was used to predict age-dependent response to drug treatments.

Results

Our analysis revealed different age-dependent gene expression spectra in ccRCC and normal kidney tissues. These findings were significant and independently reproducible in both datasets examined. Age up-regulated genes, showing higher expression in older patients, were significantly enriched (false discovery rate <0.05) in normal tissues for pathways associated with immune response and extracellular matrix organization, whereas age up-regulated genes in tumors were enriched for metabolism and oxidation pathways. Strikingly, age down-regulated genes in normal cells were also enriched for metabolism and oxidation, while those in tumors were enriched for extracellular matrix organization. Further in silico analysis of potential drug targets predicted preferential efficacy of Phosphoinositide 3-kinase inhibitor or immunotherapy in association with age.

Conclusion

We report on previously unrecognized associations between age and molecular underpinnings of RCC, including age-associated expression of genes implicated in RCC development or treatment.  相似文献   
10.
ObjectiveTo investigate whether artificial intelligence–enabled electrocardiogram (AI-ECG) assessment of atrial fibrillation (AF) risk predicts cognitive decline and cerebral infarcts.Patients and MethodsThis population-based study included sinus-rhythm ECG participants seen from November 29, 2004 through July 13, 2020, and a subset with brain magnetic resonance imaging (MRI) (October 10, 2011, through November 2, 2017). The AI-ECG score of AF risk calculated for participants was 0-1. To determine the AI-ECG-AF relationship with baseline cognitive dysfunction, we compared linear mixed-effects models with global and domain-specific cognitive z-scores from longitudinal neuropsychological assessments. The AI-ECG-AF score was logit transformed and modeled with cubic splines. For the brain-MRI subset, logistic regression evaluated correlation of the AI-ECG-AF score and the high-threshold, dichotomized AI-ECG-AF score with infarcts.ResultsParticipants (N=3729; median age, 74.1 years) underwent cognitive analysis. Adjusting for age, sex, education, and APOE ?4-carrier status, the AI-ECG-AF score correlated with lower baseline and faster decline in global-cognitive z-scores (P=.009 and P=.01, respectively, non–linear-based spline-models tests) and attention z-scores (P<.001 and P=.01, respectively). Sinus-rhythm-ECG participants (n=1373) underwent MRI. As a continuous measure, the AI-ECG-AF score correlated with infarcts but not after age and sex adjustment (P=.52). For dichotomized analysis, an AI-ECG-AF score greater than 0.5 correlated with infarcts (OR, 4.61; 95% CI, 2.45-8.55; P<.001); even after age and sex adjustment (OR, 2.09; 95% CI, 1.06-4.07; P=.03).ConclusionThe AI-ECG-AF score correlated with worse baseline cognition and gradual global cognition and attention decline. High AF probability by AI-ECG-AF score correlated with MRI cerebral infarcts. However, most infarcts observed in our cohort were subcortical, suggesting that AI-ECG not only predicts AF but also detects other non-AF cardiac disease markers and correlates with small vessel cerebrovascular disease and cognitive decline.  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